tag:theconversation.com,2011:/us/topics/electromagnetism-29958/articlesElectromagnetism – The Conversation2022-11-10T19:00:47Ztag:theconversation.com,2011:article/1940622022-11-10T19:00:47Z2022-11-10T19:00:47Z‘One of the greatest damn mysteries of physics’: we studied distant suns in the most precise astronomical test of electromagnetism yet<figure><img src="https://images.theconversation.com/files/494334/original/file-20221109-24-iwl15u.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4096%2C4096&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>There’s an awkward, irksome problem with our understanding of nature’s laws which physicists have been trying to explain for decades. It’s about electromagnetism, the law of how atoms and light interact, which explains everything from why you don’t fall through the floor to why the sky is blue. </p>
<p>Our theory of electromagnetism is arguably the best physical theory humans have ever made – but it has no answer for why electromagnetism is as strong as it is. Only experiments can tell you electromagnetism’s strength, which is measured by a number called α (aka alpha, or <a href="https://en.wikipedia.org/wiki/Fine-structure_constant">the fine-structure constant</a>).</p>
<p>The American physicist Richard Feynman, who helped come up with the theory, <a href="https://www.nature.com/articles/nphys1839">called this</a> “one of the greatest damn mysteries of physics” and urged physicists to “put this number up on their wall and worry about it”.</p>
<p>In <a href="https://doi.org/10.1126/science.abi9232">research just published in Science</a>, we decided to test whether α is the same in different places within our galaxy by studying stars that are almost identical twins of our Sun. If α is different in different places, it might help us find the ultimate theory, not just of electromagnetism, but of all nature’s laws together – the “theory of everything”.</p>
<h2>We want to break our favourite theory</h2>
<p>Physicists really want one thing: a situation where our current understanding of physics breaks down. New physics. A signal that cannot be explained by current theories. A sign-post for the theory of everything.</p>
<p>To find it, they might wait <a href="https://www.supl.org.au">deep underground in a gold mine</a> for particles of dark matter to collide with a special crystal. Or they might <a href="https://www.nature.com/articles/s41586-021-03253-4">carefully tend the world’s best atomic clocks</a> for years to see if they tell slightly different time. Or smash protons together at (nearly) the speed of light in the 27-km ring of the <a href="https://www.home.cern/science/accelerators/large-hadron-collider">Large Hadron Collider</a>.</p>
<p>The trouble is, it’s hard to know where to look. Our current theories can’t guide us. </p>
<p>Of course, we look in laboratories on Earth, where it’s easiest to search thoroughly and most precisely. But that’s a bit like the <a href="https://en.wikipedia.org/wiki/Streetlight_effect">drunk only searching for his lost keys under a lamp-post</a> when, actually, he might have lost them on the other side of the road, somewhere in a dark corner.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A detailed rainbow spectrum with many small black lines." src="https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494326/original/file-20221109-24-yxyyed.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Sun’s rainbow: sunlight is here spread into separate rows, each covering just a small range of colours, to reveal the many dark absorption lines from atoms in the Sun’s atmosphere.</span>
<span class="attribution"><a class="source" href="https://noirlab.edu/public/images/noao-sun/">N.A. Sharp / KPNO / NOIRLab / NSO / NSF / AURA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Stars are terrible, but sometimes terribly similar</h2>
<p>We decided to look beyond Earth, beyond our Solar System, to see if stars which are nearly identical twins of our Sun produce the same rainbow of colours. Atoms in the atmospheres of stars absorb some of the light struggling outwards from the nuclear furnaces in their cores. </p>
<p>Only certain colours are absorbed, leaving dark lines in the rainbow. Those absorbed colours are determined by α – so measuring the dark lines very carefully also lets us measure α.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close-up image showing the Sun's bubbling atmosphere." src="https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494328/original/file-20221109-26-mp8e2r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hotter and cooler gas bubbling through the turbulent atmospheres of stars make it hard to compare absorption lines in stars with those seen in laboratory experiments.</span>
<span class="attribution"><a class="source" href="https://nso.edu/press-release/inouye-solar-telescope-first-light/">NSO / AURA / NSF</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The problem is, the atmospheres of stars are moving – boiling, spinning, looping, burping – and this shifts the lines. The shifts spoil any comparison with the same lines in laboratories on Earth, and hence any chance of measuring α. Stars, it seems, are terrible places to test electromagnetism.</p>
<p>But we wondered: if you find stars that are very similar – twins of each other – maybe their dark, absorbed colours are similar as well. So instead of comparing stars to laboratories on Earth, we compared twins of our Sun to each other.</p>
<h2>A new test with solar twins</h2>
<p>Our team of student, postdoctoral and senior researchers, at Swinburne University of Technology and the University of New South Wales, measured the spacing between pairs of absorption lines in our Sun and 16 “solar twins” – stars almost indistinguishable from our Sun.</p>
<p>The rainbows from these stars were observed on the <a href="https://www.eso.org/sci/facilities/lasilla/telescopes/3p6.html">3.6-metre European Southern Observatory (ESO) telescope</a> in Chile. While not the largest telescope in the world, the light it collects is fed into probably the best-controlled, best-understood spectrograph: <a href="https://www.eso.org/sci/facilities/lasilla/instruments/harps.html">HARPS</a>. This separates the light into its colours, revealing the detailed pattern of dark lines. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/explainer-seeing-the-universe-through-spectroscopic-eyes-37759">Explainer: seeing the universe through spectroscopic eyes</a>
</strong>
</em>
</p>
<hr>
<p>HARPS spends much of its time observing Sun-like stars to search for planets. Handily, this provided a treasure trove of exactly the data we needed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A long-exposure photo showing stars tracing out circles in the night sky behind the silhouette of a domed telescope on a hillside." src="https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=402&fit=crop&dpr=1 600w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=402&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=402&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=505&fit=crop&dpr=1 754w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=505&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/494330/original/file-20221109-24-kj6840.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=505&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The ESO 3.6-metre telescope in Chile spends much of its time observing Sun-like stars to search for planets using its extremely precise spectrograph, HARPS.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/images/potw1043a/">Iztok Bončina / ESO</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>From these exquisite spectra, we have shown that α was the same in the 17 solar twins to an astonishing precision: just 50 parts per billion. That’s like comparing your height to the circumference of Earth. It’s the most precise astronomical test of α ever performed.</p>
<p>Unfortunately, our new measurements didn’t break our favourite theory. But the stars we’ve studied are all relatively nearby, only up to 160 light years away. </p>
<h2>What’s next?</h2>
<p>We’ve recently identified new solar twins much further away, about half way to the centre of our Milky Way galaxy.</p>
<p>In this region, there should be a much higher concentration of dark matter – an elusive substance astronomers believe lurks throughout the galaxy and beyond. Like α, we know precious little about dark matter, and <a href="https://doi.org/10.1016/j.physletb.2018.11.041">some theoretical physicists</a> suggest the inner parts of our galaxy might be just the dark corner we should search for connections between these two “damn mysteries of physics”.</p>
<p>If we can observe these much more distant suns with the largest optical telescopes, maybe we’ll find the keys to the universe.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-do-astronomers-believe-in-dark-matter-122864">Why do astronomers believe in dark matter?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/194062/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Murphy receives funding from the Australian Research Council. </span></em></p>A new study of ‘solar twins’ shows a fundamental constant appears to be the same throughout our local galactic neighbourhood.Michael Murphy, Professor of Astrophysics, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1711712021-11-24T14:44:52Z2021-11-24T14:44:52ZGreat headphones blend physics, anatomy and psychology – but what you like to listen to is also important for choosing the right pair<figure><img src="https://images.theconversation.com/files/433547/original/file-20211123-18-1o2lao8.jpg?ixlib=rb-1.1.0&rect=82%2C112%2C3448%2C3050&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Headphone designers have to balance scientific limitations with human preferences.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/close-up-of-headphones-on-microphone-stand-in-royalty-free-image/743693059?adppopup=true">Vladimir Godnik via Getty Images</a></span></figcaption></figure><p>Between music, podcasts, gaming and the unlimited supply of online content, most people <a href="https://brandongaille.com/23-headphone-industry-statistics-and-trends/">spend hours a week wearing headphones</a>. Perhaps you are considering a new pair for the holidays, but with so many options on the market, it can be hard to know what to choose.</p>
<p>I am a professional musician and a professor of <a href="https://et.iupui.edu/people/hsut">music technology who studies acoustics</a>. My work investigates the intersection between <a href="https://www.aes.org/e-lib/online/browse.cfm?elib=14210">the scientific</a>, artistic and <a href="https://www.aes.org/e-lib/browse.cfm?elib=19774">subjective human elements</a> of sound. Choosing the right headphones involves considering all three of those aspects, so what makes for a truly good pair?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing a wave and areas of higher density and lower density dots." src="https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=261&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=261&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=261&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=328&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=328&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433529/original/file-20211123-20-iz3eja.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=328&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sound is simply a series of low pressure and high pressure areas where air molecules, represented by the small dots, compress or spread apart.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:CPT-sound-physical-manifestation.svg#/media/File:CPT-sound-physical-manifestation.svg">Pluke/WikimediaCommons</a></span>
</figcaption>
</figure>
<h2>What is sound really?</h2>
<p>In physics, sound is made of air vibrations consisting of a series of high and low pressure zones. These are the cycles of a sound wave.</p>
<p>Counting the number of cycles that occur per second <a href="https://www.pearson.com/us/higher-education/program/Rossing-Science-of-Sound-The-3rd-Edition/PGM175267.html">determines the frequency, or pitch, of the sound</a>. Higher frequencies mean higher pitches. Scientists describe frequencies in hertz, so a 500 Hz sound goes through 500 complete cycles of low pressure and high pressure per second. </p>
<p>The loudness, or amplitude, of a sound is determined by the maximum pressure of a wave. The higher the pressure, the louder the sound. </p>
<p>To create sound, headphones turn an electrical audio signal into these cycles of high and low pressure that our ears interpret as sound.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram of a human ear." src="https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=455&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=455&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=455&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=572&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=572&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433533/original/file-20211123-13-12mj28o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=572&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The human ear is a complex system that turns vibrations in the air into electrical signals that go to the brain.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Ear-anatomy-text-small-en.svg#/media/File:Ear-anatomy-text-small-en.svg">Iain/WikimediaCommons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>The human ear</h2>
<p>Human ears are incredible sensors. The average person can hear a huge range of pitches and different levels of loudness. So how does the ear work?</p>
<p>When sound enters your ear, your eardrum translates the air vibrations into mechanical vibrations of the tiny middle ear bones. These mechanical vibrations become fluid vibrations in your inner ear. Sensitive nerves then turn those vibrations into electrical signals that your brain interprets as sound. </p>
<p>Although people can hear a range of pitches roughly from 20 Hz to 20,000 Hz, human hearing <a href="https://doi.org/10.1002/j.1538-7305.1933.tb00403.x">does not respond equally well at all frequencies</a>. </p>
<p>For example, if a low frequency rumble and a higher pitched bird have the same loudness, you would actually perceive the rumble to be quieter than the bird. Generally speaking, the human ear is <a href="https://doi.org/10.1121/1.1915637">more sensitive to middle frequencies than low or high pitches</a>. Researchers think this may be <a href="https://theconversation.com/testing-ancient-human-hearing-via-fossilized-ear-bones-47973">due to evolutionary factors</a>.</p>
<p>Most people don’t know that hearing sensitivity varies and, frankly, would never need to consider this phenomenon – it is simply how people hear. But headphone engineers definitely need to consider how human perception differs from pure physics. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A cutaway diagram of a speaker." src="https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=820&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=820&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=820&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1030&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1030&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433537/original/file-20211123-17-nmyltx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1030&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Speakers are fundamentally made of four components, a magnet (1), a coiled wire (2), a spring or suspension (3) and a diaphragm (4).</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Loudspeaker-bass.png#/media/File:Loudspeaker-bass.png">Svjo/WkimediaCommons</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>How do headphones work?</h2>
<p>Headphones – both bigger varieties that sit over your ears as well as small earbuds – are just small speakers. Simply put, speakers do the opposite of your ear: They convert the electrical signals from your phone, record player or computer into vibrations in air. </p>
<p>Most speakers are made of four components: a stationary magnet, a wire coil that moves back and forth around that magnet, a diaphragm that pushes air and a suspension that holds the diaphragm.</p>
<p>Electromagnetism states that when a wire is wrapped around a magnet and the current within the wire changes, the <a href="https://www.sciencedirect.com/book/9780240809694/handbook-for-sound-engineers">magnetic field around the wire changes proportionally</a>. When the electrical signal of a song or podcast pulses through the wires in a set of headphones, it changes the current and moves the magnet. The magnet then moves the diaphragm in and out – kind of like a plunger – pushing and compressing air, creating pulses of high pressure and low pressure. This is the music that you hear.</p>
<p>Ideally, a speaker would convert the electrical signals of the input perfectly into sound representations. However, the real physical world has limitations. Things like the size and material of the magnet and diaphragm all prevent a speaker from perfectly matching its output to its input. This leads to distortion and some frequencies being louder or softer than the original. </p>
<p>While no headphone can perfectly recreate the signal, there are infinite different ways to choose to distort that signal. The reason two equally expensive headphones can sound or feel different is that they distort things in different ways. When engineers build new headphones, they have to not only consider how human hearing distorts sound, but also the physical limitations of any speaker.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man outside wearing headphones." src="https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/433542/original/file-20211123-21-1kgd80t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">What you like to listen to and how you like your headphones to sound play a huge role in determining what makes for a ‘good’ pair of headphones.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/rear-view-of-man-listening-to-headphones-at-beach-royalty-free-image/543201647?adppopup=true">Matt Dutile/Image Source via Getty Images</a></span>
</figcaption>
</figure>
<h2>Listener preference</h2>
<p>If all the complications of ears and speakers weren’t enough, listeners themselves play a huge role in deciding what makes for a “good” pair of headphones. Aspects like age, experience, culture and music genre preference <a href="http://www.aes.org/e-lib/browse.cfm?elib=17500">all affect what kind of frequency distortion someone will prefer</a>. Headphones are as much <a href="https://www.aes.org/e-lib/online/browse.cfm?elib=16768">a question of personal taste</a> as anything else. </p>
<p>For example, some people prefer bass-heavy headphones for hip-hop music, while classical music listeners may want less frequency distortion. But music or recreational listening aren’t the only things to consider. Headphones for the hearing impaired may highlight frequencies from approximately 1,000 Hz to 5,000 Hz, as <a href="https://doi.org/10.1044/1059-0889.0603.48">this helps to make speech more understandable</a>.</p>
<p>You could certainly play a hip-hop song through headphones designed for the hearing impaired, but most people would agree that the results aren’t going to sound very good. Making sure the headphones you choose match how you are going to use them goes a long way in determining what will sound good.</p>
<p>Ultimately, the science of headphone design, the artistry of the content creators and the human experience all intersect to form the perception of “good” headphones. Despite all these moving pieces, there is one foolproof way to know when headphones are good: choose a good song and put a pair on! Because when all the attributes align, a good pair of headphones can give you the opportunity to be transformed by sound.</p><img src="https://counter.theconversation.com/content/171171/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy Hsu is a member of the Acoustical Society of America and an executive board member for the Indiana Section of the Audio Engineering Society.</span></em></p>There is a lot to consider when buying a new pair of headphones. A professional musician and acoustics researcher explains how the science of sound and quirks of human hearing make for a great listening experience.Timothy Hsu, Assistant Professor of Music and Arts Technology, IUPUILicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1680322021-09-16T14:17:54Z2021-09-16T14:17:54ZDo the northern lights make sounds that you can hear?<figure><img src="https://images.theconversation.com/files/421574/original/file-20210916-13-39kdxt.jpeg?ixlib=rb-1.1.0&rect=14%2C0%2C4977%2C3173&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/spectacular-auroral-display-over-glacier-lagoon-143438332">John A Davis/Shutterstock</a></span></figcaption></figure><p>It’s a question that has <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsnr.2021.0031">puzzled observers for centuries</a>: do the fantastic green and crimson light displays of the aurora borealis produce any discernible sound? </p>
<p>Conjured by the interaction of solar particles with gas molecules in Earth’s atmosphere, the aurora generally occurs <a href="https://www.ncei.noaa.gov/news/science-beauty-and-mystery-auroras">near Earth’s poles</a>, where the magnetic field is strongest. Reports of the aurora making a noise, however, are rare – and were historically dismissed by scientists.</p>
<p>But a <a href="https://www.researchgate.net/profile/Unto-Laine/publication/304252270_Auroral_Acoustics_project_-_a_progress_report_with_a_new_hypothesis/links/576aba0208aefcf135bd4c60/Auroral-Acoustics-project-a-progress-report-with-a-new-hypothesis.pdf">Finnish study</a> in 2016 claimed to have finally confirmed that the northern lights really do produce sound audible to the human ear. <a href="https://www.youtube.com/watch?v=NRZfKqhs6rM&ab_channel=AaltoUniversity">A recording</a> made by one of the researchers involved in the study even claimed to have captured the sound made by the captivating lights 70 metres above ground level.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/NRZfKqhs6rM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Still, the mechanism behind the sound remains somewhat mysterious, as are the conditions that must be met for the sound to be heard. <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsnr.2021.0031">My recent research</a> takes a look over historic reports of auroral sound to understand the methods of investigating this elusive phenomenon and the process of establishing whether reported sounds were objective, illusory of imaginary.</p>
<h2>Historic claims</h2>
<p>Auroral noise was the subject of particularly lively debate in the first decades of the 20th century, when accounts from settlements across northern latitudes reported that sound sometimes accompanied the mesmerising light displays in their skies.</p>
<p>Witnesses told of a quiet, almost imperceptible crackling, whooshing or whizzing noise during particularly violent northern lights displays. In the early 1930s, for instance, <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsnr.2021.0031">personal testimonies</a> started flooding into The Shetland News, the weekly newspaper of the subarctic Shetland Islands, likening the sound of the northern lights to “rustling silk” or “two planks meeting flat ways”.</p>
<p>These tales were corroborated by similar testimony from northern Canada and Norway. Yet the scientific community was less than convinced, especially considering very few western explorers claimed to have heard the elusive noises themselves.</p>
<figure class="align-center ">
<img alt="A black and white image of aurora" src="https://images.theconversation.com/files/421594/original/file-20210916-15-7ooisf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421594/original/file-20210916-15-7ooisf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=528&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421594/original/file-20210916-15-7ooisf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=528&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421594/original/file-20210916-15-7ooisf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=528&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421594/original/file-20210916-15-7ooisf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=664&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421594/original/file-20210916-15-7ooisf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=664&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421594/original/file-20210916-15-7ooisf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=664&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An early photograph of the aurora, captured in 1930 in Finnmark, Norway.</span>
<span class="attribution"><span class="source">Nasjonalbiblioteket, Norway</span></span>
</figcaption>
</figure>
<p>The credibility of auroral noise reports from this time was intimately tied to altitude measurements of the northern lights. It was considered that only those displays that descended low into the Earth’s atmosphere would be able to transmit sound which could be heard by the human ear. </p>
<p>The problem here was that results recorded during the <a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/TR015i001p00166-2">Second International Polar Year of 1932-3</a> found aurorae most commonly took place 100km above Earth, and very rarely below 80km. This suggested it would be impossible for discernible sound from the lights to be transmitted to the Earth’s surface.</p>
<h2>Auditory illusions?</h2>
<p>Given these findings, eminent physicists and meteorologists remained sceptical, dismissing accounts of auroral sound and very low aurorae as folkloric stories or auditory illusions. </p>
<p>Sir Oliver Lodge, the British physicist involved in the development of radio technology, <a href="https://royalsocietypublishing.org/doi/full/10.1098/rsnr.2021.0031">commented that</a> auroral sound might be a psychological phenomenon due to the vividness of the aurora’s appearance – just as meteors sometimes <a href="https://www.nature.com/articles/023529e0">conjure a whooshing sound</a> in the brain. Similarly, the meteorologist George Clark Simpson argued that the appearance of low aurorae was likely an <a href="https://www.nature.com/articles/127663a0">optical illusion</a> caused by the interference of low clouds.</p>
<p>Nevertheless, the leading auroral scientist of the 20th century, Carl Størmer, <a href="https://www.nature.com/articles/119045b0">published accounts</a> written by two of his assistants who claimed to have heard the aurora, adding some legitimacy to the large volume of personal reports. </p>
<figure class="align-center ">
<img alt="A scientist in the snow" src="https://images.theconversation.com/files/421583/original/file-20210916-23-1tkr9v2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421583/original/file-20210916-23-1tkr9v2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=500&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421583/original/file-20210916-23-1tkr9v2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=500&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421583/original/file-20210916-23-1tkr9v2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=500&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421583/original/file-20210916-23-1tkr9v2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=629&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421583/original/file-20210916-23-1tkr9v2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=629&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421583/original/file-20210916-23-1tkr9v2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=629&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Carl Størmer observing the northern lights.</span>
<span class="attribution"><a class="source" href="https://www.nb.no/items/eddfe10bb9dd8e017ad15ae8b305bbf4?page=0&searchText=carl%20stormer">Nasjonalbiblioteket, Norway</a></span>
</figcaption>
</figure>
<p>Størmer’s assistant Hans Jelstrup said he had heard a “very curious faint whistling sound, distinctly undulatory, which seemed to follow exactly the vibrations of the aurora”, while Mr Tjönn experienced a sound like “burning grass or spray”. As convincing as these two last testimonies may have been, they still didn’t propose a mechanism by which auroral sound could operate.</p>
<h2>Sound and light</h2>
<p>The answer to this enduring mystery which has subsequently garnered the most support was first tentatively suggested in 1923 by <a href="http://adsabs.harvard.edu/pdf/1923JRASC..17..273C">Clarence Chant</a>, a well-known Canadian astronomer. He argued that the motion of the northern lights alters Earth’s magnetic field, inducing changes in the electrification of the atmosphere, even at a significant distance. </p>
<p>This electrification produces a crackling sound much closer to Earth’s surface when it meets objects on the ground, much like the sound of static. This could take place on the observer’s clothes or spectacles, or possibly in surrounding objects including fir trees or the cladding of buildings. </p>
<p>Chant’s theory correlates well with many accounts of auroral sound, and is also supported by occasional reports of the smell of ozone – which reportedly carries a <a href="https://www.scientificamerican.com/article/storm-scents-smell-rain/">metallic odour</a> similar to an electrical spark – during northern lights displays. </p>
<p>Yet Chant’s paper went largely unnoticed in the 1920s, only receiving recognition in the 1970s when <a href="https://www.sciencedirect.com/science/article/pii/S0065268708603520?casa_token=A_jSDHN45qoAAAAA:2Cb-cn5RsGRYmBvvOAdcMO5jY5PL5KLK1vvhn_xB-iCzdABUFIUG9CtpPcoR2ho-lVtLdxM1m-o">two auroral physicists</a> revisited the historical evidence. Chant’s theory is largely accepted by scientists today, although there’s <a href="https://research.aalto.fi/en/publications/localization-of-sound-sources-in-temperature-inversion-layer-duri/fingerprints/?sortBy=alphabetically">still debate</a> as to how exactly the mechanism for producing the sound operates. </p>
<p>What is clear is that the aurora does, on rare occasions, make sounds audible to the human ear. The eerie reports of crackling, whizzing and buzzing noises accompanying the lights describe an objective audible experience – not something illusory or imagined.</p>
<h2>Sampling the sound</h2>
<p>If you want to hear the northern lights for yourself, you may have to spend a considerable amount of time in the Polar regions, considering the aural phenomenon only presents itself in <a href="http://adsabs.harvard.edu/pdf/1933JRASC..27..184B">5% of violent auroral displays</a>. It’s also most commonly heard on the top of mountains, surrounded by only a few buildings – so it’s not an especially accessible experience. </p>
<p>In recent years, the sound of the aurora has nonetheless been explored for its aesthetic value, inspiring musical compositions and laying the foundation for novel ways of interacting with its electromagnetic signals. </p>
<p>The Latvian composer <a href="https://d1wqtxts1xzle7.cloudfront.net/60412911/DUE_NORTH__ERIKS_ESENVALDS_AND_AURORA_BOREALIS_AS_A_CLAIMED_ARTISTIC_SPACE-with-cover-page-v2.pdf?Expires=1631459602&Signature=B-TmBsJ4tS5TRtn4FXi-qnTLs64dLuUR9EqiE7Jcqv9vPUf8FQqvjDAp9eeMyNg-guwTUOVVYxskN41O6jUyRCzdq1Z1NnusC%7E%7EWt5RNzxEdFsh7iEs%7EexnZvm14xwn-SmBp6gi30tVW3wxoV1qqL0Rprl4ZMWmmAUtGU8g6YB%7EpBxq9udl-XEfAOyOoOonKRkFZYpg8ybvAia7bZu9vaAlBYLP7ZJu0jvTjN4sA830Mz9051KuFcArUVccA51pmdc4Y72%7ExdbwxhBft7g6frPVO1QlfbS2OMgWisCdcx4dUtP0IVWvI6Dv9PceF86EW6x7CmSsnkUnsSuJuKYzxVA__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA">Ēriks Ešenvalds</a> has used journal extracts from the American explorer Charles Hall and the Norwegian statesman Fridjtof Nansen, both of whom claimed to have heard the northern lights, in his music. His composition, <a href="https://www.youtube.com/watch?v=jh09QDoJMMg">Northern Lights</a>, interweaves these reports with the only known Latvian folksong recounting the auroral sound phenomenon, sung by a tenor solo.</p>
<p>Or you can also listen to the radio signals of the northern lights at home. In 2020, a <a href="https://www.bbc.co.uk/programmes/m000qhj3">BBC 3 radio programme</a> remapped very low frequency radio recordings of the aurora onto the audible spectrum. Although not the same as perceiving audible noises produced by the the northern lights in person on a snowy mountaintop, these radio frequencies give an awesome sense of the aurora’s transitory, fleeting and dynamic nature.</p><img src="https://counter.theconversation.com/content/168032/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Fiona Amery does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Depending on who you ask, the northern lights may, very occasionally, sound like ‘rustling silk’ or ‘two planks meeting flat ways’.Fiona Amery, PhD Candidate in History and Philosophy of Science, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1514222020-12-23T13:41:03Z2020-12-23T13:41:03ZMagnetic induction cooking can cut your kitchen’s carbon footprint<figure><img src="https://images.theconversation.com/files/376248/original/file-20201221-19-2jat4u.jpg?ixlib=rb-1.1.0&rect=15%2C0%2C2101%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Bye-bye, burners.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/pot-in-modern-kitchen-with-induction-stove-royalty-free-image/501706822?adppopup=true">brizmaker/iStock/Getty Images Plus</a></span></figcaption></figure><p>To curb climate change, many experts have called for <a href="https://www.nytimes.com/interactive/2020/04/19/climate/climate-crash-course-4.html">a massive shift from fossil fuels to electricity</a>. The goal is to electrify processes like heating homes and powering cars, and then generate the increased electrical power needs using low- or zero-carbon sources like wind, solar and hydropower.</p>
<p>More than 30 cities in California, including <a href="https://www.sfchronicle.com/bayarea/article/Berkeley-becomes-first-U-S-city-to-ban-natural-14102242.php">Berkeley</a> and <a href="https://www.sfchronicle.com/bayarea/article/No-more-natural-gas-in-new-San-Francisco-15717658.php">San Francisco</a>, have moved in this direction by banning natural gas service in most new buildings. Currently energy use in buildings generates <a href="https://sfgov.org/scorecards/environment/greenhouse-gas-emissions">over 40% of San Francisco’s greenhouse gas emissions</a>. </p>
<p>There are straightforward electric options for heating buildings and hot water and drying clothes, but going electric could be more controversial in the kitchen. Traditional electric stoves are notoriously slow to heat up and cool down. They also pose safety issues because their heating coils can stay hot for tens of minutes after they are shut off.</p>
<p>What is a serious cook to do? One high-tech alternative is magnetic induction. This technology was first proposed over 100 years ago and <a href="http://www.historyofmicrowave.com/microwave-history/history-of-induction-cooker/">demonstrated at the 1933 Chicago World’s Fair</a>. Today magnetic induction stoves and cooktops are common in Europe and Asia, but remain <a href="https://www.nytimes.com/wirecutter/blog/why-dont-people-use-induction-cooktops/">a niche technology in the U.S.</a> As <a href="https://www.forbes.com/sites/energyinnovation/2019/07/22/as-cities-begin-banning-natural-gas-states-must-embrace-building-electrification-with-smart-policy/?sh=2a54e4166ce6">more cities and states move toward electrification</a>, here’s a look at how magnetic induction works and its pros and cons for cooking. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/glH71fM9Oe4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Electrical Engineer Bill Kornrumpf describes how magnetic induction cooking works.</span></figcaption>
</figure>
<h2>Heating without a flame</h2>
<p>I am an <a href="https://scholar.google.com/citations?user=VcXxSfkAAAAJ&hl=en">electrical engineer specializing in electromagnetic field research</a>. Much of my work focuses on medical therapy applications – but whether you are exposing human tissue or a pan on a cooktop to electromagnetic fields, the principles are the same.</p>
<p>To understand what electromagnetic fields are, the key principle is that an electric charge creates a field around it – essentially, a force that extends in all directions. Think of static electricity, which is an electric charge often produced by friction. If you rub a balloon on your hair, the friction will charge the balloon with static electric charge; then when you lift the balloon away from your head your hair will rise, even if the balloon isn’t touching it. The balloon is pulling on your hair with an attractive electric force.</p>
<p>Moving electric charges, like electricity flowing through wire, produce magnetic fields – zones of magnetic force around the current’s path. The Earth has a magnetic field because electric currents are flowing in its molten core.</p>
<p>Magnetic fields can also produce electric fields and this is why we use the term electromagnetic fields. This concept was discovered in the 1830s by <a href="https://www.britannica.com/biography/Michael-Faraday">English scientist Michael Faraday</a>, who showed that if an electrically conductive material, such as a wire, is placed in a moving magnetic field, an electric field is created in the conductor. We call this magnetic induction. If the conductor is formed into a loop, an electric current will flow around the loop. </p>
<p>Faraday’s discovery formed the basis for the <a href="https://nationalmaglab.org/education/magnet-academy/watch-play/interactive/faraday-motor">development of electric motors</a>. His work also demonstrated a way to heat materials without using a traditional heat source such as fire.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1337517515820306432"}"></div></p>
<h2>Where does the heat come from?</h2>
<p>All materials have resistance, which means that when electric current flows through them, the flow will be <a href="https://www.physicsclassroom.com/class/circuits/Lesson-3/Resistance">hindered at least somewhat</a>. This resistance causes some of the electric energy to be lost: The energy turns into heat, and as a result the conductor warms up. In my biomedical research we investigate using radio frequency magnetic fields to heat up tissues in the body to <a href="https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=890.5290">help the tissue heal</a>. </p>
<p>Instead of conventional burners, the cooking spots on induction cooktops are called hobs, and consist of wire coils embedded in the cooktop’s surface. For maximum efficiency, engineers want as much as possible of the magnetic field energy produced by each hob to be absorbed by the cookware sitting on it. The magnetic field will create an electric field in the bottom of the cookware, and because of resistance the pan will heat up, even though the hob does not.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing how magnetic induction cooking works." src="https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=466&fit=crop&dpr=1 600w, https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=466&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=466&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=586&fit=crop&dpr=1 754w, https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=586&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/376269/original/file-20201221-21-1oewx6z.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=586&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Magnetic coils below the cooktop’s ceramic glass surface generate a magnetic field that sends pulses directly to the cookware. These magnetic pulses are what heat the cookware.</span>
<span class="attribution"><a class="source" href="https://www.sanjoseca.gov/your-government/departments-offices/environmental-services/climate-smart-san-jos/induction-cooktop-checkout-program">City of San Jose</a></span>
</figcaption>
</figure>
<p>For the best performance, magnetic induction stoves and cooktops need to operate at a high magnetic field frequency – typically, 24KHz. They also require pots made from materials that magnetic fields do not readily pass through. Metals with high iron or nickel content absorb magnetic fields, so they are the most efficient options for induction cooking. Iron absorbs magnetic fields more readily than nickel and is far less expensive, so iron-based materials are most commonly used for magnetic induction cookware.</p>
<h2>More responsive and safer, but more expensive</h2>
<p>Since induction cooktops require something to absorb magnetic fields in order to produce heat, they are intrinsically safer than a traditional electric cooktop. Placing your hand on the hob will not heat up your hand to any noticeable extent. And since these systems heat cookware without directly heating the hob, the hobs cool quickly after the cookware is removed, which reduces the risk of burns.</p>
<p>The cookware itself tends to warm up and cool down quickly, and temperature control is very accurate – one of the key properties that cooks value in gas stoves. Another plus is that induction cooktops commonly have smooth surfaces – often glass or ceramic – so they are easy to clean. </p>
<p>Modern induction cooktops are as energy-efficient as traditional electric stoves and about twice as efficient as gas stoves. But this does not necessarily mean they are less expensive to operate. In many parts of the U.S. <a href="https://www.consumeraffairs.com/homeowners/gas-vs-electric-appliances.html">natural gas is far cheaper than electricity</a>, sometimes by a factor of three or four. This partly explains broader acceptance of induction cooktops in Europe, where until recently natural gas was much more expensive than electricity. </p>
<p><iframe id="aSuM3" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/aSuM3/1/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>Another factor that has influenced adoption is that induction stoves and cooktops typically <a href="https://www.nytimes.com/wirecutter/blog/why-dont-people-use-induction-cooktops/">cost more than traditional gas or electric stoves</a>, although not substantially so. And cooks will have to replace aluminum, copper, nonmagnetic stainless steel and ceramic pots, none of which work effectively on induction cooktops. One quick check is that if a magnet sticks to the bottom of a pot, the pot will work on an induction cooktop.</p>
<p>[<em>The Conversation’s science, health and technology editors pick their favorite stories.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-favorite">Weekly on Wednesdays</a>.]</p>
<p>Despite these factors, I expect that natural gas use reduction ordinances will lead to greatly expanded use of magnetic induction stoves and cooktops. These measures typically focus on newly constructed buildings, so they will not require <a href="https://www.greentechmedia.com/articles/read/whole-home-electrification-electricity-is-cheap-so-why-stop-at-net-zero">expensive conversions of existing homes</a>. </p>
<p>Young singles and families who move into these new residences may not yet have acquired a lot of cookware, and are likely to appreciate the safety associated with magnetic induction, especially if they have children. And early adopters who are willing to pay more for electricity from green sources, or for a hybrid or electric car, may not be upset about paying a few hundred dollars more for a magnetic induction cooktop and pans that work with it.</p>
<p>At the national level, the U.S. may <a href="https://eelp.law.harvard.edu/2020/11/president-elect-biden-supports-a-carbon-enforcement-mechanism-could-that-mean-a-price-on-carbon/">adopt some form of carbon pricing</a> in the near future, which would raise the cost of natural gas. And there is also growing concern about <a href="https://coeh.ph.ucla.edu/effects-residential-gas-appliances-indoor-and-outdoor-air-quality-and-public-health-california">indoor air pollution from gas appliances</a>. More than a century after it was first proposed, magnetic induction cooking’s day in the sun may have arrived.</p><img src="https://counter.theconversation.com/content/151422/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kenneth McLeod does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Shifting from fossil fuels to electricity is climate-friendly, but serious cooks don’t think much of electric stoves. Will induction cooking finally catch on as an alternative?Kenneth McLeod, Professor of Systems Science, and Director, Clinical Science and Engineering Research Laboratory, Binghamton University, State University of New YorkLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1210172019-08-08T09:30:09Z2019-08-08T09:30:09ZKepler’s forgotten ideas about symmetry help explain spiral galaxies without the need for dark matter – new research<figure><img src="https://images.theconversation.com/files/285739/original/file-20190725-136728-aaxtby.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">M81 spiral galaxy.</span> <span class="attribution"><span class="source">NASA/JPL-Caltech/ESA/Harvard-Smithsonian CfA</span></span></figcaption></figure><p>The 17th-century astronomer <a href="https://doi.org/10.3189/S0022143000020013">Johannes Kepler</a> was the first to muse about the structure of snowflakes. Why are they so symmetrical? How does one side know how long the opposite side has grown? Kepler thought it was all down to what we would now call a <a href="https://en.wikipedia.org/wiki/Morphogenetic_field">“morphogenic field”</a> – that things <em>want</em> to have the form they have. Science has since discounted this idea. But the question of why snowflakes and similar structures are so symmetrical is nevertheless not entirely understood.</p>
<p>Modern science shows just how fundamental the question is: look at all the spiral galaxies out there. They can be half a million light years across, but they still preserve their symmetry. How? In our <a href="http://dx.doi.org/10.1038/s41598-019-46765-w">new study</a>, published in <a href="https://www.nature.com/srep/">Scientific Reports</a>, we present an explanation. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/285911/original/file-20190726-43126-170umci.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285911/original/file-20190726-43126-170umci.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285911/original/file-20190726-43126-170umci.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285911/original/file-20190726-43126-170umci.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285911/original/file-20190726-43126-170umci.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285911/original/file-20190726-43126-170umci.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285911/original/file-20190726-43126-170umci.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Real snowflake.</span>
<span class="attribution"><span class="source">Karen Schanely: https://www.clickinmoms.com/blog/take-macro-snowflakes-pictures/; public domain</span></span>
</figcaption>
</figure>
<p>We have shown that information and “entropy” – a measure of the disorder of a system – are linked together (“info-entropy”) in a way exactly analogous to electric and magnetic fields (“electromagnetism”). Electric currents produce magnetic fields, while changing magnetic fields produce electric currents. Information and entropy influence each other in the same way.</p>
<p>Entropy is a fundamental concept in physics. For example, because entropy can never decrease (disorder always increases) you can turn an egg into scrambled eggs but not the other way around. If you move information around you must also increase entropy – a phone call has <a href="https://eandt.theiet.org/content/articles/2010/07/entropy-analysis-threatens-to-turn-efficient-computing-on-its-head/">an entropy cost</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/287340/original/file-20190808-144888-x8ziyr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287340/original/file-20190808-144888-x8ziyr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=318&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287340/original/file-20190808-144888-x8ziyr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=318&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287340/original/file-20190808-144888-x8ziyr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=318&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287340/original/file-20190808-144888-x8ziyr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=400&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287340/original/file-20190808-144888-x8ziyr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=400&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287340/original/file-20190808-144888-x8ziyr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=400&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Light wave with electric (E) and magnetic (B) fields.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>We showed that entropy and information can be treated as a field and that they are related to geometry. Think of the two strands of the <a href="https://en.wikipedia.org/wiki/DNA">DNA</a> double helix winding around each other. Light waves <a href="https://en.wikipedia.org/wiki/Electromagnetic_radiation">have the same structure</a>, where the two strands are the electric and magnetic fields. We showed mathematically that the relationship between information and entropy can be visualised using just the same geometry.</p>
<p>We wanted to see if our theory could predict things in the real world, and decided to try and calculate how much energy you’d need to convert one form of DNA to another. DNA is after all a spiral and a form of information. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/285875/original/file-20190726-43114-9fk0s3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285875/original/file-20190726-43114-9fk0s3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=252&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285875/original/file-20190726-43114-9fk0s3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=252&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285875/original/file-20190726-43114-9fk0s3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=252&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285875/original/file-20190726-43114-9fk0s3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=316&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285875/original/file-20190726-43114-9fk0s3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=316&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285875/original/file-20190726-43114-9fk0s3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=316&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Two forms of DNA.</span>
<span class="attribution"><span class="source">Parker & Jeynes, Fig.1 of Scientific Reports 9|10779 (2019); Modified from Fig. 5 of Allemand et al. Proc. Natl. Acad. Sci. USA 95, 14152–14157 (1998)</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>This was actually done in extraordinarily precise <a href="http://dx.doi.org/10.1038/nature01810">measurements</a> some 16 years ago. The researchers pulled a DNA molecule straight (DNA likes to curl up), and twisted it 4,800 turns while holding the ends with <a href="https://theconversation.com/arthur-ashkins-optical-tweezers-the-nobel-prize-winning-technology-that-changed-biology-104282">optical tweezers</a>. The DNA flipped from one form to another, as in the picture above. The researchers could then calculate the energy difference between the two forms. </p>
<p>But our theory could calculate this energy difference, too. We knew the entropy of each of the two versions of this DNA molecule, and the energy is simply the product of entropy and temperature. Our result was spot on – the theory seemed to hold up.</p>
<h2>From tiny to enormous</h2>
<p>Spiral galaxies are double spirals just as DNA is a double helix – mathematically speaking they have similar geometries. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/285831/original/file-20190726-43153-1ru6eaz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/285831/original/file-20190726-43153-1ru6eaz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=383&fit=crop&dpr=1 600w, https://images.theconversation.com/files/285831/original/file-20190726-43153-1ru6eaz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=383&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/285831/original/file-20190726-43153-1ru6eaz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=383&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/285831/original/file-20190726-43153-1ru6eaz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=482&fit=crop&dpr=1 754w, https://images.theconversation.com/files/285831/original/file-20190726-43153-1ru6eaz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=482&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/285831/original/file-20190726-43153-1ru6eaz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=482&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A spiral galaxy with an overlaid double-armed logarithmic spiral.</span>
<span class="attribution"><span class="source">Parker & Jeynes, Fig.2 of Scientific Reports 9|10779 (2019)</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Our theory shows directly why the two arms of the spiral galaxies are symmetrical – it’s because info-entropy fields give rise to forces (like other fields). The stars in the galaxy are simply choreographed by an entropic force to line up into a pair of such spirals to maximise entropy.</p>
<p>But we wanted to get some real numbers, too. We therefore decided to try to calculate the mass of our galaxy from our theory. We know how heavy the Milky Way appears to be from how fast the stars move near the galactic edge – it is about 1.3 trillion sun masses.</p>
<p>Strangely, this is actually much more than the mass of all the visible stars in the galaxy. To be able to explain this discrepancy and account for why stars move so much faster than expected, astronomers came up with the idea of “<a href="https://theconversation.com/from-machos-to-wimps-meet-the-top-five-candidates-for-dark-matter-51516">dark matter</a>” – unseen mass lurking in the galaxy, increasing its gravitational pull on the stars.</p>
<p>We needed to know the entropy of the galaxy for our calculations. Luckily, the mathematical physicist <a href="https://en.wikipedia.org/wiki/Roger_Penrose">Roger Penrose</a> showed that <a href="https://en.wikipedia.org/wiki/Cycles_of_Time">this entropy</a> is dominated by the entropy of its central <a href="https://en.wikipedia.org/wiki/Supermassive_black_hole">super-massive black hole</a>.</p>
<p>We know the mass of this black hole (4.3m sun masses). And amazingly, when you know the mass of a black hole, there is an <a href="http://www.scholarpedia.org/article/Bekenstein-Hawking_entropy">equation</a>, discovered by the late physicist <a href="https://en.wikipedia.org/wiki/Stephen_Hawking">Stephen Hawking</a>, that calculates its entropy. Hawking also discovered how to calculate the <a href="https://en.wikipedia.org/wiki/Hawking_radiation">“temperature” at its surface, or “event horizon”</a>.</p>
<p>If you can assign a “temperature” to the black hole event horizon – which has no stuff in it to have temperature – why not also assign a temperature to a galaxy? We argue in our paper that this is reasonable (using what’s known as the <a href="https://www.scientificamerican.com/article/sidebar-the-holographic-p/">“holographic principle”</a>). So we used our info-entropy equations to calculate the galaxy’s holographic temperature. </p>
<p>Then it gets easy. We know that the galactic energy is given by the product of its entropy and temperature. And when we know the energy we can find out the mass thanks to <a href="https://www.britannica.com/science/E-mc2-equation">Einstein’s famous equation</a>: E=mc<sup>2</sup>.</p>
<p>This time the result was not exactly spot on, but it was reasonably close given our highly simplified model of the galaxy. The info-entropic geometry of a galaxy not only explains how entropic forces create the beautifully symmetric shape and keep it, but also accounts for all the mass that appears to be evident in it. </p>
<p>This means that we don’t actually need dark matter after all. According to our model, the galactic entropy gives rise to such a large quantity of additional energy that it modifies the observed dynamics of the galaxy – making stars at the edge move faster than expected. This is exactly what dark matter was meant to explain. The energy isn’t directly observable as mass, but its presence is certainly supported by the astronomical observations – explaining why dark matter searches have so far found nothing. </p>
<p>There is a lot of research supporting the idea of dark matter though. Our theory suggests an alternative explanation of the observations, and needs no new physics. Of course, more detailed work is needed to verify that the true complexity of the observations can also be modelled successfully.</p>
<p>We think that the “morphogenic field” Kepler was seeking really does exist, and is actually the effect of the intertwining of information and entropy. After four long centuries, it seems Kepler has finally been vindicated.</p><img src="https://counter.theconversation.com/content/121017/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research does away with dark matter by putting ‘entropy’, a measure of disorder, at the heart of the universe.Chris Jeynes, Senior researcher, University of SurreyMichael Parker, Visiting Fellow, University of EssexLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/947002018-05-23T10:39:19Z2018-05-23T10:39:19ZThe Standard Model of particle physics: The absolutely amazing theory of almost everything<figure><img src="https://images.theconversation.com/files/219824/original/file-20180521-14978-36nv6i.jpg?ixlib=rb-1.1.0&rect=174%2C0%2C977%2C649&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">How does our world work on a subatomic level?</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Varsha_ys.jpg">Varsha Y S</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The Standard Model. What a dull name for the most accurate scientific theory known to human beings.</p>
<p>More than a quarter of the Nobel Prizes in physics of the last century are direct inputs to or direct results of the Standard Model. Yet its name suggests that if you can afford a few extra dollars a month you should buy the upgrade. <a href="https://scholar.google.com/citations?user=eQiX0m4AAAAJ&hl=en&oi=ao">As a theoretical physicist</a>, I’d prefer The Absolutely Amazing Theory of Almost Everything. That’s what the Standard Model really is.</p>
<p>Many recall the excitement among scientists and media over the 2012 <a href="https://home.cern/topics/higgs-boson">discovery of the Higgs boson</a>. But that much-ballyhooed event didn’t come out of the blue – it capped a five-decade undefeated streak for the Standard Model. Every fundamental force but gravity is included in it. Every attempt to overturn it to demonstrate in the laboratory that it must be substantially reworked – and there have been many over the past 50 years – has failed. </p>
<p>In short, the <a href="https://home.cern/about/physics/standard-model">Standard Model</a> answers this question: What is everything made of, and how does it hold together?</p>
<h2>The smallest building blocks</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=533&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=533&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219828/original/file-20180521-14991-vlfgkx.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=533&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">But these elements can be broken down further.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Periodic_table_vectorial.png">Rubén Vera Koster</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>You know, of course, that the world around us is made of molecules, and molecules are made of atoms. Chemist <a href="https://www.famousscientists.org/dmitri-mendeleev/">Dmitri Mendeleev</a> figured out in the 1860s how to organize all atoms – that is, the elements – into the periodic table that you probably studied in middle school. But there are 118 different chemical elements. There’s antimony, arsenic, aluminum, selenium … and 114 more.</p>
<p>Physicists like things simple. We want to boil things down to their essence, a few basic building blocks. Over a hundred chemical elements is not simple. The ancients believed that everything is made of just five elements – <a href="https://en.wikipedia.org/wiki/Classical_element">earth, water, fire, air and aether</a>. Five is much simpler than 118. It’s also wrong. </p>
<p>By 1932, scientists knew that all those atoms are made of just three particles – neutrons, protons and electrons. The neutrons and protons are bound together tightly into the nucleus. The electrons, thousands of times lighter, whirl around the nucleus at speeds approaching that of light. Physicists <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1918/planck-bio.html">Planck</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1922/bohr-bio.html">Bohr</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1933/schrodinger-bio.html">Schroedinger</a>, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1932/heisenberg-bio.html">Heisenberg</a> and friends had invented a new science – <a href="https://en.wikipedia.org/wiki/Quantum_mechanics">quantum mechanics</a> – to explain this motion.</p>
<p>That would have been a satisfying place to stop. Just three particles. Three is even simpler than five. But held together how? The negatively charged electrons and positively charged protons are bound together by <a href="https://en.wikipedia.org/wiki/Electromagnetism">electromagnetism</a>. But the protons are all huddled together in the nucleus and their positive charges should be pushing them powerfully apart. The neutral neutrons can’t help. </p>
<p>What binds these protons and neutrons together? “Divine intervention” a man on a Toronto street corner told me; he had a pamphlet, I could read all about it. But this scenario seemed like a lot of trouble even for a divine being – keeping tabs on every single one of the universe’s 10⁸⁰ protons and neutrons and bending them to its will. </p>
<h2>Expanding the zoo of particles</h2>
<p>Meanwhile, nature cruelly declined to keep its zoo of particles to just three. Really four, because we should count the <a href="https://en.wikipedia.org/wiki/Photon">photon</a>, the particle of light that <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1921/einstein-bio.html">Einstein</a> described. Four grew to five when <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1936/anderson-bio.html">Anderson</a> measured electrons with positive charge – positrons – striking the Earth from outer space. At least <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1933/dirac-bio.html">Dirac</a> had predicted these first anti-matter particles. Five became six when the pion, which <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1949/yukawa-bio.html">Yukawa</a> predicted would hold the nucleus together, was found. </p>
<p>Then came the muon – 200 times heavier than the electron, but otherwise a twin. “Who ordered that?” <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1944/rabi-bio.html">I.I. Rabi</a> quipped. That sums it up. Number seven. Not only not simple, redundant.</p>
<p>By the 1960s there were hundreds of “fundamental” particles. In place of the well-organized periodic table, there were just long lists of baryons (heavy particles like protons and neutrons), mesons (like <a href="https://en.wikipedia.org/wiki/Hideki_Yukawa">Yukawa</a>’s pions) and leptons (light particles like the electron, and the elusive neutrinos) – with no organization and no guiding principles.</p>
<p>Into this breach sidled the Standard Model. It was not an overnight flash of brilliance. No Archimedes leapt out of a bathtub shouting “eureka.” Instead, there was a series of crucial insights by a few key individuals in the mid-1960s that transformed this quagmire into a simple theory, and then five decades of experimental verification and theoretical elaboration. </p>
<p><a href="https://home.cern/about/updates/2014/01/fifty-years-quarks">Quarks</a>. They come in six varieties we call flavors. Like ice cream, except not as tasty. Instead of vanilla, chocolate and so on, we have up, down, strange, charm, bottom and top. In 1964, <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1969/gell-mann-bio.html">Gell-Mann</a> and <a href="https://www.macfound.org/fellows/113/">Zweig</a> taught us the recipes: Mix and match any three quarks to get a baryon. Protons are two ups and a down quark bound together; neutrons are two downs and an up. Choose one quark and one antiquark to get a meson. A pion is an up or a down quark bound to an anti-up or an anti-down. All the material of our daily lives is made of just up and down quarks and anti-quarks and electrons.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=536&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=536&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=536&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=673&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=673&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219958/original/file-20180522-51127-4tx5tr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=673&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Standard Model of elementary particles provides an ingredients list for everything around us.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Standard_Model_From_Fermi_Lab.jpg">Fermi National Accelerator Laboratory</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Simple. Well, simple-ish, because keeping those quarks bound is a feat. They are tied to one another so tightly that you never ever find a quark or anti-quark on its own. The theory of that binding, and the particles called gluons (chuckle) that are responsible, is called <a href="https://en.wikipedia.org/wiki/Quantum_chromodynamics">quantum chromodynamics</a>. It’s a vital piece of the Standard Model, but mathematically difficult, even posing an unsolved problem of basic mathematics. We physicists do our best to calculate with it, but we’re still learning how.</p>
<p>The other aspect of the Standard Model is “<a href="https://doi.org/10.1103/PhysRevLett.19.1264">A Model of Leptons</a>.” That’s the name of the landmark 1967 paper by <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/1979/weinberg-bio.html">Steven Weinberg</a> that pulled together quantum mechanics with the vital pieces of knowledge of how particles interact and organized the two into a single theory. It incorporated the familiar electromagnetism, joined it with what physicists called “the weak force” that causes certain radioactive decays, and explained that they were different aspects of the same force. It incorporated <a href="https://www.nobelprize.org/nobel_prizes/physics/laureates/2013/higgs-facts.html">the Higgs mechanism</a> for giving mass to fundamental particles. </p>
<p>Since then, the Standard Model has predicted the results of experiment after experiment, including the discovery of several varieties of quarks and of the <a href="https://en.wikipedia.org/wiki/W_and_Z_bosons">W and Z bosons</a> – heavy particles that are for weak interactions what the photon is for electromagnetism. The possibility that <a href="https://en.wikipedia.org/wiki/Neutrino#Mass">neutrinos aren’t massless</a> was overlooked in the 1960s, but slipped easily into the Standard Model in the 1990s, a few decades late to the party.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/219960/original/file-20180522-51095-vverdp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">3D view of an event recorded at the CERN particle accelerator showing characteristics expected from the decay of the SM Higgs boson to a pair of photons (dashed yellow lines and green towers).</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:3D_view_of_an_event_recorded_with_the_CMS_detector_in_2012_at_a_proton-proton_centre_of_mass_energy_of_8_TeV.png">McCauley, Thomas; Taylor, Lucas; for the CMS Collaboration CERN</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Discovering the Higgs boson in 2012, long predicted by the Standard Model and long sought after, was a thrill but not a surprise. It was yet another crucial victory for the Standard Model over the dark forces that particle physicists have repeatedly warned loomed over the horizon. Concerned that the Standard Model didn’t adequately embody their expectations of simplicity, worried about its mathematical self-consistency, or looking ahead to the eventual necessity to bring the force of gravity into the fold, physicists have made numerous proposals for theories beyond the Standard Model. These bear exciting names like <a href="https://en.wikipedia.org/wiki/Grand_Unified_Theory">Grand Unified Theories</a>, <a href="https://en.wikipedia.org/wiki/Supersymmetry">Supersymmetry</a>, <a href="https://en.wikipedia.org/wiki/Technicolor_(physics)">Technicolor</a>, and <a href="https://en.wikipedia.org/wiki/String_theory">String Theory</a>. </p>
<p>Sadly, at least for their proponents, beyond-the-Standard-Model theories have not yet successfully predicted any new experimental phenomenon or any experimental discrepancy with the Standard Model.</p>
<p>After five decades, far from requiring an upgrade, the Standard Model is <a href="http://artsci.case.edu/smat50/">worthy of celebration</a> as the Absolutely Amazing Theory of Almost Everything.</p><img src="https://counter.theconversation.com/content/94700/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Glenn Starkman receives funding from the Office of Science of the US Department of Energy. He is affiliated with Case Western Reserve University. </span></em></p>A particle physicist explains just what this keystone theory includes. After 50 years, it’s the best we’ve got to answer what everything in the universe is made of and how it all holds together.Glenn Starkman, Distinguished University Professor of Physics, Case Western Reserve UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/927112018-03-29T10:29:39Z2018-03-29T10:29:39ZSpace weather threatens high-tech life<figure><img src="https://images.theconversation.com/files/212007/original/file-20180326-159081-ibu4ks.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A coronal mass ejection erupts from the sun in 2012.</span> <span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/11095">NASA</a></span></figcaption></figure><p>Shortly after 4 a.m. on a crisp, cloudless September morning in 1859, the sky above what is currently Colorado erupted in bright red and green colors. Fooled by the brightness into <a href="https://arstechnica.com/science/2012/05/1859s-great-auroral-stormthe-week-the-sun-touched-the-earth/">thinking it was an early dawn</a>, gold-rush miners in the mountainous region of what was then called the Kansas Territory woke up and started making breakfast. What happened in more developed regions was even more disorienting, and carries a warning for the wired high-tech world of the 21st century.</p>
<p>As the sky lit up over the nighttime side of the Earth, <a href="https://io9.gizmodo.com/how-the-carrington-event-let-telegraphs-run-on-aurora-p-1686759750">telegraph systems worldwide went berserk</a>, clacking nonsense code and emitting large sparks that ignited fires in nearby piles of paper tape. Telegraph operators <a href="https://science.nasa.gov/science-news/science-at-nasa/2008/06may_carringtonflare">suffered electrical burns</a>. Even disconnecting the telegraph units from their power sources <a href="https://science.nasa.gov/science-news/science-at-nasa/2008/06may_carringtonflare">didn’t stop the frenzy</a>, because the transmission wires themselves were carrying huge electrical currents. Modern technology had just been humbled by a fierce space weather storm that had arrived from the sun, the <a href="http://doi.org/10.1029/2011SW000734">largest ever recorded</a> – and more than twice as powerful as a storm nine years earlier, which had itself been the largest in known history.</p>
<p>My seven years of research on predicting solar storms, combined with my decades using GPS satellite signals under <a href="http://www.cis.rit.edu/%7Errdpci/space-weather.html">various solar storm conditions</a>, indicate that today’s even more sensitive electronics and satellites would be devastated should an event of that magnitude occur again. In 2008, a panel of experts commissioned by the National Academy of Sciences issued a detailed report with a sobering conclusion: The world would be <a href="https://www.nap.edu/catalog/12643/severe-space-weather-events-understanding-societal-and-economic-impacts-a">thrown back to the life of the early 1800s</a>, and it would take years – or even a decade – to recover from an event that large. </p>
<h2>A solar explosion</h2>
<p>Space weather storms have happened since the birth of the solar system, and have <a href="https://arxiv.org/ftp/arxiv/papers/0902/0902.3446.pdf">hit Earth many times</a>, both before and after that massive event in 1859, which was named the <a href="https://arstechnica.com/science/2012/05/1859s-great-auroral-stormthe-week-the-sun-touched-the-earth/">Carrington event</a> after a British astronomer who <a href="http://www.solarstorms.org/SCarrington.html">recorded his observations of the sun</a> at the time. They’re caused by huge electromagnetic explosions on the surface of the sun, called <a href="https://www.swpc.noaa.gov/phenomena/coronal-mass-ejections">coronal mass ejections</a>. Each explosion sends billions of protons and electrons, in a <a href="http://pluto.space.swri.edu/image/glossary/plasma.html">superheated ball of plasma</a>, out into the solar system.</p>
<p><a href="https://spacemath.gsfc.nasa.gov/weekly/3Page27.pdf">About 1 in every 20</a> coronal mass ejections heads in a direction that <a href="https://theconversation.com/how-facebook-the-wal-mart-of-the-internet-dismantled-online-subcultures-71536">intersects Earth’s orbit</a>. <a href="https://www.spaceweatherlive.com/en/help/how-do-we-know-if-a-cme-is-earth-directed-and-when-its-going-to-arrive">Around three days later</a>, our planet experiences what is called a space weather storm or a geomagnetic storm. </p>
<p>While these events are described using terms like “weather” and “storm,” they do not affect whether it’s rainy or sunny, hot or cold, or other aspects of what it’s like outdoors on any given day. Their effects are not meteorological, but only electromagnetic. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/212010/original/file-20180326-159081-14mbyu0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Aurorae are signs of a geomagnetic storm.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/goddard/2017/northern-lights-over-alaska-2">NASA/Terry Zaperach</a></span>
</figcaption>
</figure>
<h2>Hitting Earth</h2>
<p>When the coronal mass ejection arrives at Earth, the charged particles collide with air molecules in the upper atmosphere, generating heat and <a href="https://www.timeanddate.com/astronomy/northern-southern-lights.html">light called aurora</a>.</p>
<p>Also, as happens anytime <a href="https://www.youtube.com/watch?v=DVcvKwEUYqk">moving electrical charges encounter a magnetic field</a>, the interaction creates a spontaneous electrical current in any conductor that’s available. If the plasma ball is big enough, its interaction with Earth’s magnetic field can induce <a href="https://doi.org/10.1002/swe.20065">large currents on long wires</a> on the ground, like the one that overloaded telegraph circuits in 1859.</p>
<p><iframe id="6KR2O" class="tc-infographic-datawrapper" src="https://datawrapper.dwcdn.net/6KR2O/2/" height="400px" width="100%" style="border: none" frameborder="0"></iframe></p>
<p>On March 13, 1989, a storm only about <a href="https://www.swpc.noaa.gov/noaa-scales-explanation">one-fifth as strong</a> as the Carrington event hit Earth. It induced a large surge of current in the long power lines of the <a href="http://www.hydroquebec.com/learning/notions-de-base/tempete-mars-1989.html">Hydro-Quebec power grid</a>, causing physical damage to transmission equipment and leaving <a href="https://www.scientificamerican.com/article/geomagnetic-storm-march-13-1989-extreme-space-weather/">6 million people without power for nine hours</a>. Another storm-induced power surge <a href="https://spectrum.ieee.org/energy/the-smarter-grid/a-perfect-storm-of-planetary-proportions">destroyed a large transformer</a> at a New Jersey nuclear plant. Even though a spare transformer was nearby, it still took <a href="http://www.solarstorms.org/SWChapter1.html">six months to remove and replace</a> the melted unit. Some people worried that the bright auroral lights meant <a href="https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/06/08/trumps-budget-eliminates-program-that-detects-infrastructure-crippling-solar-storms/">nuclear war had broken out</a>.</p>
<p>And in October 2003, a rapid series of solar storms affected Earth. Collectively called the Halloween solar storm, this series <a href="https://www.nasa.gov/topics/solarsystem/features/halloween_storms.html">caused surges</a> that <a href="https://www.directionsmag.com/article/1510">threatened the North American power grid</a>. Its <a href="https://www.space.com/23396-scary-halloween-solar-storm-2003-anniversary.html">effects on satellites</a> made GPS navigation erratic and interrupted communications connections during the peak of the storm.</p>
<p>Larger storms will have wider effects, cause more damage and take longer to recover from.</p>
<h2>Wide-reaching effects</h2>
<p>Geomagnetic storms attack the lifeblood of modern technology: electricity. A space weather storm typically lasts for two or three days, during which the entire planet is subjected to powerful electromagnetic forces. The <a href="https://www.nap.edu/catalog/12643/severe-space-weather-events-understanding-societal-and-economic-impacts-a">National Academy of Sciences study</a> concluded that an especially massive storm would damage and shut down power grids and communications networks worldwide.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/209611/original/file-20180308-30961-ghoyz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Electricity, shown in the upper right, is integrated into every aspect of modern life.</span>
<span class="attribution"><a class="source" href="https://www.fcc.gov/help/public-safety-tech-topic-19-communications-interdependencies">Federal Communications Commission</a></span>
</figcaption>
</figure>
<p>After the storm passed, there would be no simple way to restore power. Manufacturing plants that build replacements for burned-out lines or power transformers would have no electricity themselves. Trucks needed to deliver raw materials and finished equipment wouldn’t be able to fuel up, either: Gas pumps run on electricity. And what pumps were running would soon dry up, because electricity also runs the machinery that extracts oil from the ground and refines it into usable fuel. </p>
<p>With transportation stalled, food wouldn’t get from farms to stores. Even systems that seem non-technological, like public water supplies, would shut down: Their pumps and purification systems need electricity. People in developed countries would find themselves with no running water, no sewage systems, no refrigerated food, and no way to get any food or other necessities transported from far away. People in places with more basic economies would also be without needed supplies from afar.</p>
<p>It could take <a href="https://www.nap.edu/catalog/12643/severe-space-weather-events-understanding-societal-and-economic-impacts-a">between four and 10 years</a> to repair all the damage. In the meantime, people would need to grow their own food, find and carry and purify water, and cook meals over fires.</p>
<p>Some systems would continue to operate, of course: bicycles, horse-drawn carriages and sailing ships. But another type of equipment that would keep working provides a clue to preventing this type of disaster: Electric cars would continue to work, but only in places where there were solar panels and wind turbines to recharge them.</p>
<h2>Preparing and protecting</h2>
<p>Geomagnetic storms would affect those small-scale installations far less than grid-scale systems. It’s a basic principle of electricity and magnetism that the longer a wire that’s exposed to a moving magnetic field, the <a href="https://doi.org/10.1016/S1364-6826(02)00126-8">larger the current that’s induced</a> in that wire.</p>
<p>In 1859, the telegraph system was so profoundly affected because it had wires stretching from city to city across the U.S. Those very long wires had to handle enormous amounts of energy all at once, and failed. Today, there are long runs of wires connecting power generators to consumers – such as <a href="https://www.eia.gov/todayinenergy/detail.php?id=27152">from Niagara Falls to New York City</a> – that would be similarly susceptible to large induced currents.</p>
<p>The only way to reduce vulnerability to geomagnetic storms is to substantially revamp the power grid. Now, it is a <a href="https://www.eia.gov/todayinenergy/detail.php?id=27152">vast web of wires</a> that effectively spans continents. Governments, businesses and communities need to work together to split it into much smaller components, each serving a town or perhaps even a neighborhood – or an individual house. These “<a href="https://www.energy.gov/articles/how-microgrids-work">microgrids</a>” can be connected to each other, but should have <a href="https://science.nasa.gov/science-news/science-at-nasa/2010/26oct_solarshield">protections built in</a> to allow them to be disconnected quickly when a storm approaches. That way, the length of wires affected by the storm will be shorter, reducing the potential for damage.</p>
<p>A family using solar panels and batteries for storage and an electric car to get around would likely find its water supply, natural gas or internet service disrupted. But their freedom to travel, and to use electric lights to work after dark, would provide a much better chance at survival.</p>
<h2>When will the next storm hit?</h2>
<p>People should start preparing today. It’s impossible to know when a major storm will hit next: The most we’ll get is a <a href="https://theconversation.com/new-solar-storm-forecasting-technique-breaks-the-24-hour-warning-barrier-for-earth-42917">three-day warning</a> when something happens on the surface of the sun. It’s really only a matter of time before there is another one like the Carrington event.</p>
<p><a href="https://doi.org/10.1063/1.4993929">Solar astrophysicists</a> are also studying the sun to identify any events or conditions that might herald a coronal mass ejection. They’re collecting enormous amounts of data about the sun and using computer analysis to try to connect that information to geomagnetic storms on Earth. This work is underway and will become more refined over time. The research has not yet yielded a reliable prediction of a coming solar storm before an ejection occurs, but it improves each year. </p>
<p>In my view, the safest course of action involves developing microgrids based on renewable energy. That would not only improve people’s quality of life around the planet right now, but also provide the best opportunity to maintain that lifestyle when adverse events happen.</p><img src="https://counter.theconversation.com/content/92711/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Roger Dube has previously received funding from the National Aeronautics and Space Administration (NASA). </span></em></p>The wired Earth of the 21st century is at the mercy of the volatile nature of the sun.Roger Dube, Research Professor of Imaging Science, Rochester Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/851292017-10-31T10:53:51Z2017-10-31T10:53:51ZNorthern lights to death rays: how electromagnetism haunts our everyday life<figure><img src="https://images.theconversation.com/files/192498/original/file-20171030-18738-b5bc8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pink lightning</span> <span class="attribution"><a class="source" href="https://pixabay.com/en/lightning-storm-spark-weather-sky-2822445/">Oranfireblade/Pixabay</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Electromagnetism has haunted the human imagination for thousands of years. From the ghostly Northern Lights of ancient aurora mythology to the evil electromagnetic forces in the popular TV show <a href="http://www.sho.com/twin-peaks">Twin Peaks</a>, electromagnetic energy continues to endure as a source of spooky speculation. Its mystical fields and mysterious frequencies have inspired spiritualists, New Agers, paranormal investigators and conspiracy theorists alike. </p>
<p>Electromagnetism was first discovered in the 19th century, when scientists recognised that the interaction of electrical currents and magnets could make objects move without touching. This suggested that the apparently distinct forces of electricity and magnetism were actually intimately related. <a href="https://en.wikipedia.org/wiki/Hans_Christian_%C3%98rsted">Hans Christian Ørsted</a>, <a href="https://en.wikipedia.org/wiki/Michael_Faraday">Michael Faraday</a> and <a href="https://en.wikipedia.org/wiki/James_Clerk_Maxwell">James Clerk Maxwell</a> proposed that invisible electromagnetic “fields” and “waves” were behind this spooky action at a distance. Their experiments marked the beginning of the Electromagnetic Age and paved the way for a radical new understanding of the dynamics of the universe. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192084/original/file-20171026-13327-17zl3je.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/192084/original/file-20171026-13327-17zl3je.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=448&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192084/original/file-20171026-13327-17zl3je.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=448&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192084/original/file-20171026-13327-17zl3je.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=448&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192084/original/file-20171026-13327-17zl3je.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=563&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192084/original/file-20171026-13327-17zl3je.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=563&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192084/original/file-20171026-13327-17zl3je.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=563&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Danish physicist Hans Christian Ørsted discovers electromagnetism in 1820.</span>
<span class="attribution"><span class="source">Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>Victorians suddenly found themselves living in a world newly conceived as awash with unseen electromagnetic entities. And these dynamic forces, fields and fluxes provided a logic and a language for occult occurrences.</p>
<h2>Physical to psychical</h2>
<p>New technologies were developed to visualise, access and unlock the mysteries of this previously unseen and inaccessible energy-world. The telegraph and, later, the radio, tapped into unseen regions of electromagnetic radiation. These technologies allowed for a form of disembodied communication that opened up imaginative possibilities for contacting the dead. Media historian <a href="https://www.dukeupress.edu/haunted-media">Jeffrey Sconce</a> has explored the role of the electromagnetic imagination in the spiritualist movement, for whom the mysterious force offered a vital link between physical and psychical realms. </p>
<p>Electromagnetism continued to figure prominently in 20th-century explorations of the supernatural. UFO, poltergeist and other paranormal encounters were often accompanied by a disturbance of the local electromagnetic environment – white noise on radios, static on television sets, car engines switching off or domestic appliances acting strangely (tropes that persistently feature in horror and sci-fi TV shows from <a href="http://www.imdb.com/title/tt0106179/">The X-Files</a> to <a href="http://www.imdb.com/title/tt4574334/?ref_=nv_sr_1">Stranger Things</a>). Electromagnetic wavelength filters and field meters were deployed to register these energetic presences. For some, however, the real spooks were not the ghosts or aliens but the electromagnetic fields themselves, generated by the <a href="http://www.jerryesmith.com/index.php/4">transmission towers</a> of the military-industrial complex.</p>
<p>Electromagnetism proved a wellspring for conspiracy theories related to energy weapons, mind control and weather warfare. Early experiments with wireless transmissions had led to many inventors, including <a href="https://en.wikipedia.org/wiki/Nikola_Tesla">Nikola Tesla</a>, <a href="https://en.wikipedia.org/wiki/Guglielmo_Marconi">Guglielmo Marconi</a> and <a href="https://en.wikipedia.org/wiki/Harry_Grindell_Matthews">Harry Grindell Matthews</a>, claiming they had built a “death-ray” that could direct a powerful blast of electromagnetic energy. The mysterious <a href="http://www.bbc.co.uk/earth/story/20160706-in-siberia-in-1908-a-huge-explosion-came-out-of-nowhere">Tunguska Event</a> of 1908 in Siberia – the largest impact event on Earth in recorded history – may be linked to Tesla’s electromagnetic energy beam experiments.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192088/original/file-20171026-13327-awjmyg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/192088/original/file-20171026-13327-awjmyg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=453&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192088/original/file-20171026-13327-awjmyg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=453&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192088/original/file-20171026-13327-awjmyg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=453&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192088/original/file-20171026-13327-awjmyg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192088/original/file-20171026-13327-awjmyg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192088/original/file-20171026-13327-awjmyg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Nikola Tesla circa 1899, next to his high-voltage ‘magnifying transmitter’</span>
<span class="attribution"><span class="source">Dickenson V. Alley/Wikimedia Commons</span></span>
</figcaption>
</figure>
<p>The Soviet Union’s <a href="http://www.30-years-later.com/duga-radar-the-russian-woodpecker/">Duga Radar System</a> (that released the famous Russian Woodpecker signal around the world) and the US government’s <a href="https://www.livescience.com/45829-haarp-shutdown.html">High Frequency Active Auroral Research Programme (HAARP)</a> instigated “tin-foil hat” fears of radio frequency brainwashing. There is speculation that the recent “<a href="https://www.theguardian.com/world/2017/sep/14/mystery-of-sonic-weapon-attacks-at-us-embassy-in-cuba-deepens">health attacks</a>” on American diplomats at the US embassy in Cuba were carried out with some sort of directed electromagnetic energy weapon. </p>
<h2>Everyday electromagnetism</h2>
<p>Often <a href="http://www.bioinitiative.org">dismissed</a> as pseudoscientific paranoia, these fringe theories nevertheless expressed a growing concern about the health risks of living within an increasingly electromagnetic environment. Alongside the natural electromagnetic activity of lightning storms, auroras and space weather, an accelerating array of man-made electromagnetic fields were being generated by modern electrical appliances and the power grids, radio antennae and mobile phone masts of the industrial landscape.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/192308/original/file-20171028-13367-1yi3vng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/192308/original/file-20171028-13367-1yi3vng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/192308/original/file-20171028-13367-1yi3vng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/192308/original/file-20171028-13367-1yi3vng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/192308/original/file-20171028-13367-1yi3vng.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/192308/original/file-20171028-13367-1yi3vng.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/192308/original/file-20171028-13367-1yi3vng.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The ghostly incandescence of the Northern Lights.</span>
<span class="attribution"><span class="source">MattHPhotos/Pixabay</span></span>
</figcaption>
</figure>
<p>Cultural anxieties surrounding this electromagnetic “pollution” were succinctly articulated by Don DeLillo in his 1985 novel <a href="https://en.wikipedia.org/wiki/White_Noise_(novel)">White Noise</a>:</p>
<blockquote>
<p>The real issue is the kind of radiation that surrounds us every day. Your radio, your TV, your microwave oven, your power lines… Forget spills, fallouts, leakages. It’s the things right around you in your own house that’ll get you sooner or later. It’s the electrical and magnetic fields. </p>
</blockquote>
<p>More recently, in Mark Frost and David Lynch’s 2017 revival of <a href="http://www.sho.com/twin-peaks">Twin Peaks</a>, the ambient electromagnetism that forms the background of our technology-driven daily lives becomes an omnipotent sinister force. The mundane landscape of electromagnetic infrastructure – the pylons, telegraph poles and plug sockets we’ve trained ourselves not to see – take on supernatural significance as portal-generators to extradimensional negative spaces. </p>
<p>Lynch’s films often work to reveal the horrifying forces beneath the mundane surface of everyday life – <a href="https://www.youtube.com/watch?v=TwuzI8Y0uW0">take a look</a> at the palpitating insects swarming amid the manicured suburban lawns of <a href="http://www.imdb.com/title/tt0090756/">Blue Velvet</a>: </p>
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<p>For Lynch, it seems, the really scary thing about electromagnetism is how such a mysterious force can appear so utterly mundane – the way this strange energy is permanently present yet never noticed; the way the monolithic infrastructure goes by completely unseen; the way we seem too anaesthetised and technology-dependent for the possibility of fear or fascination to even arise. Here, the truly disturbing thing about electromagnetism is not that it reveals a weird new world, but that it reveals how blind we are to the everyday weirdness of the world.</p>
<p>Today, in our world of ubiquitous WiFi, smartphones, data streams and contactless emanations, it is the data ghosts of our digital lives that we increasingly imagine to haunt the electromagnetic realm. </p>
<p>Mysterious yet mundane, palpable yet immaterial and existing at the edges of perceptible experience, the energies, forces and fluxes of electromagnetism continue to power and perturb everyday life.</p><img src="https://counter.theconversation.com/content/85129/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>A.R.E. Taylor does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A look at the spooky side of electromagnetism in our culture.A.R.E. Taylor, PhD Candidate in Social Anthropology, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/826012017-08-24T14:06:12Z2017-08-24T14:06:12ZHow to store data on magnets the size of a single atom<figure><img src="https://images.theconversation.com/files/183289/original/file-20170824-25612-fy7mwk.png?ixlib=rb-1.1.0&rect=24%2C247%2C1193%2C845&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Magnetism is useful in many ways, and the magnetic memory effect appears even at the atomic level.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:PSM_V83_D111_Force_flow_of_a_magnetized_steel_sphere.png">Popular Science Monthly</a></span></figcaption></figure><p>There is an adage that says that data will expand to fill all available capacity. Perhaps ten or 20 years ago, it was common to stockpile software programs, MP3 music, films and other files, which may have taken years to collect. In the days when hard disk drives offered a few tens of gigabytes of storage, running out of space was almost inevitable.</p>
<p>Now that we have fast broadband internet and think nothing of downloading a 4.7 gigabyte DVD, we can amass data even more quickly. Estimates of the total amount of data held worldwide are to rise from <a href="https://www.emc.com/leadership/digital-universe/2014iview/executive-summary.htm">4.4 trillion gigabytes in 2013 to 44 trillion gigabytes by 2020</a>. This means that we are generating an average of 15m gigabytes per day. Even though hard disk drives are now measured in thousands of gigabytes rather than tens, we still have a storage problem.</p>
<p>Research and development is focused on developing new means of data storage that are more dense and so can store greater amounts of data, and do so in a more energy efficient way. Sometimes this involves updating established techniques: recently IBM announced a <a href="https://www.theverge.com/2017/8/2/16074568/ibm-330-terabytes-record-uncompressed-data-cartridge-cartridge-tape">new magnetic tape technology</a> that can store 25 gigabytes per square inch, a new world record for the 60-year-old technology. While current magnetic or solid-state consumer hard drives are more dense at around <a href="http://www.computerworld.com/article/3030642/data-storage/flash-memorys-density-surpasses-hard-drives-for-first-time.html">200 gigabytes per square inch</a>, magnetic tapes are still frequently used for data back-up. </p>
<p>However, the cutting edge of data storage research is working at the level of individual atoms and molecules, representing the ultimate limit of technological miniaturisation. </p>
<h2>The quest for atomic magnets</h2>
<p>Current magnetic data storage technologies – those used in traditional hard disks with spinning platters, the standard until a few years ago and still common today – are built using “top-down” methods. This involves making thin layers from a large piece of ferromagnetic material, each containing the many <a href="https://www.nde-ed.org/EducationResources/HighSchool/Magnetism/magneticdomain.htm">magnetic domains</a> that are used to hold data. Each of these magnetic domains is made of a large collection of magnetised atoms, whose magnetic polarity is set by the hard disk’s read/write head to represent data as either a binary one or zero.</p>
<p>An alternative “bottom-up” method would involve constructing storage devices by placing individual atoms or molecules one by one, each capable of storing a single bit of information. Magnetic domains retain their magnetic memory due to communication between groups of neighbouring magnetised atoms.</p>
<p>Single-atom or single-molecule magnets on the other hand do not require this communication with their neighbours to retain their magnetic memory. Instead, the memory effect arises from quantum mechanics. So because atoms or molecules are much, much smaller than the magnetic domains currently used, and can be used individually rather than in groups, they can be packed more closely together which could result in an enormous increase in data density.</p>
<p>Working with atoms and molecules like this is not science fiction. Magnetic memory effects in single-molecule magnets (SMMs) were <a href="http://dx.doi.org/10.1038/365141a0">first demonstrated in 1993</a>, and <a href="http://dx.doi.org/10.1126/science.aad9898">similar effects for single-atom magnets</a> were shown in 2016. </p>
<h2>Raising the temperature</h2>
<p>The main problem standing in the way of moving these technologies out of the lab and into the mainstream is that they do not yet work at ambient temperatures. Both single atoms and SMMs require cooling with liquid helium (at a temperature of –269°C), an expensive and limited resource. So research effort over the last 25 years has concentrated on raising the temperature at which <a href="https://www.doitpoms.ac.uk/tlplib/ferromagnetic/hysteresis.php">magnetic hysteresis</a> – a demonstration of the magnetic memory effect – can be observed. An important target is –196°C, because this is the temperature that can be achieved with liquid nitrogen, which is abundant and cheap.</p>
<p>It took 18 years for the first substantive step towards raising the temperature in which magnetic memory is possible in SMMs – an increase of 10°C <a href="http://dx.doi.org/10.1021/ja206286h">achieved by researchers in California</a>. But now our research team at the University of Manchester’s School of Chemistry have <a href="http://dx.doi.org/10.1038/nature23447">achieved magnetic hysteresis in a SMM at –213 °C</a> using a new molecule based on the rare earth element dysprosocenium, as reported in a letter to the journal Nature. With a leap of 56°C, this is only 17°C away from the temperature of liquid nitrogen.</p>
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<h2>Future uses</h2>
<p>There are other challenges, however. In order to practically store individual bits of data, molecules must be fixed to surfaces. This has been <a href="http://dx.doi.org/10.1038/nmat2374">demonstrated with SMMs in the past</a>, but not for this latest generation of high-temperature SMMs. On the other hand, <a href="http://dx.doi.org/10.1126/science.aad9898">magnetic memory in single atoms</a> has already been demonstrated on a surface.</p>
<p>The ultimate test is demonstration of writing and non-destructively reading data in single atoms or molecules. This was achieved for the first time in 2017 by a group of researchers at IBM who demonstrated the <a href="http://spectrum.ieee.org/nanoclast/semiconductors/nanotechnology/single-atom-serves-as-worlds-smallest-magnet-and-data-storage-device">world’s smallest magnetic memory storage device</a>, built around a <a href="http://dx.doi.org/10.1038/nature21371">single atom</a>.</p>
<p>But regardless of whether single-atom or single-molecule storage devices ever become truly practical, the advancements in fundamental science being made along this path are phenomenal. The synthetic chemistry techniques developed by groups working on SMMs now allow us to design molecules with customised magnetic properties, which will have applications in quantum computing and even magnetic resonance imaging.</p><img src="https://counter.theconversation.com/content/82601/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr. Nicholas Chilton receives funding from the EPSRC, the Ramsay Memorial Trust and the University of Manchester.</span></em></p>Work to develop a single-atom magnet that works at room temperature has just taken a big leap forward.Nicholas Chilton, Research Fellow - School of Chemistry, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/576612016-08-08T20:07:17Z2016-08-08T20:07:17ZExplainer: the mysterious missing magnetic monopole<figure><img src="https://images.theconversation.com/files/132937/original/image-20160803-12207-vsll31.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">All the magnets we've ever seen have a north and a south, but there might be some out there that have only one end.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>You’ve probably heard of the <a href="https://theconversation.com/au/topics/higgs-boson">Higgs boson</a>. This elusive particle was predicted to exist long ago and helped explain why the universe works the way it does, but it took decades for us to detect.</p>
<p>Well, there’s another elusive particle that has also been predicted by quantum physics, and it’s been missing for an even longer time. In fact, we still haven’t spotted one, and not through lack of trying. </p>
<p>It’s called the magnetic monopole, and it has a few unique properties that make it rather special.</p>
<h2>Parallels</h2>
<p>Those with an interest in physics are probably already familiar with an <em>electric</em> monopole, although you may know it by its more common name: electric charge. </p>
<p>Opposite electric charges attract and like charges repel through the interaction of electric fields, which are defined as running from positive to negative. These are the somewhat arbitrary labels for the two opposing electric charges. </p>
<p>Electric monopoles exist in the form of particles that have a positive or negative electric charge, such as protons or electrons.</p>
<p>At first glance, magnetism seems somewhat analogous to electricity, as there exists a magnetic field with a direction defined as running from north to south. </p>
<p>However, the analogy breaks down when we try to find the magnetic counterpart for the electric charge. While we can find electric monopoles in the form of charged particles, we have never observed magnetic monopoles. </p>
<p>Instead, magnets exist only in the form of dipoles with a north and a south end. When a bar magnet is split into two pieces, you don’t get a separate north part and a south part. Rather you get two new, smaller magnets, each with a north and south end.</p>
<p>Even if you split that magnet down into individual particles, you still get a magnetic dipole. </p>
<p>When we look at magnetism in the world, what we see is entirely consistent with <a href="https://www.theguardian.com/science/2013/sep/15/maxwells-equations-electrify-world">Maxwell’s equations</a>, which describe the unification of electric and magnetic field theory into classical electromagnetism. </p>
<p>They were first published by James Maxwell during 1861 and 1862 and are still used daily on a practical level in engineering, telecommunications and medical applications, to name just a few.</p>
<p>But one of these equations – Gauss’s law for magnetism – states that there are no magnetic monopoles.</p>
<p>The magnetism we observe on a day-to-day basis can all be attributed to the movement of electric charges. When an electrically charged particle moves along a path, such as an electron moving down a wire, this is an electrical current. This induces a magnetic field that wraps around the direction of the current.</p>
<p>The second cause of magnetism involves a property from quantum mechanics called “spin”. This can be thought of in terms of an electrically charged particle rotating on an axis rather than moving in a particular direction. </p>
<p>This generates an angular momentum in the particle, causing the electron to act as a magnetic dipole (i.e. a tiny bar magnet). This means we can describe magnetic phenomena without the need for magnetic monopoles.</p>
<p>But just because our classical electromagnetic theories are consistent with our observations, that does not imply that there are no magnetic monopoles. Rather, this just means that there are no magnetic monopoles anywhere that we have <em>observed</em>. </p>
<p>Once we start to delve into the murky depths of theory, we begin to find some tempting arguments for their presence in the universe. </p>
<h2>The lure of duality</h2>
<p>In 1894, Nobel Laureate <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1903/pierre-curie-bio.html">Pierre Curie</a> discussed the possibility of such an undiscovered particle and could find no reason to discount its existence. </p>
<p>Later, in 1931, Nobel Laureate <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1933/dirac-bio.html">Paul Dirac</a> showed that when Maxwell’s equations are extended to include a magnetic monopole, electric charge can exist only in discrete values. </p>
<p>This “quantisation” of electric charge is one of the requirements of quantum mechanics. So Dirac’s work went towards showing that classical electromagnetism and quantum electrodynamics were compatible theories in this sense.</p>
<p>Finally, there are few physicists who can resist the beauty of symmetry in nature. And because the existence of a magnetic monopole would imply a duality between electricity and magnetism, the theory suggesting magnetic monopoles becomes almost intoxicating. </p>
<p>Duality, in the physical sense, is when two different theories can be related in such a way that one system is analogous to the other. </p>
<p>If it were the case that the electric force was completely analogous to the magnetic force, then perhaps other forces would also be analogous to one another. Perhaps then there would be some way to relate the strong nuclear force to the weak nuclear force, paving the way to a grand unification of all physical forces.</p>
<p>Of course, just because a theory has an appealing symmetry doesn’t make it correct. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/132938/original/image-20160803-12196-16cpxs9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A single magnetic monopole might be hiding out there somewhere.</span>
<span class="attribution"><a class="source" href="http://moedal.web.cern.ch/images">CERN/MoEDAL</a></span>
</figcaption>
</figure>
<h2>Monopole mirage</h2>
<p>Scientists have come close to seeing magnetic monopoles by producing <a href="http://phys.org/news/2014-01-physicists-synthetic-magnetic-monopole-years.html">monopole-like structures</a> in the lab using complex arrangements of magnetic fields in Bose-Einstein condensates and superfluids. </p>
<p>But, while these show that a magnetic monopole is not a physical impossibility, they are not the same as discovering one in nature. </p>
<p>Particle physics experiments have, on occasion, announced <a href="http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.35.487">possible</a> <a href="http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.48.1378">monopole</a> candidates, but so far none of these discoveries have been shown to be irrefutable or reproducible. </p>
<p>The Monopole and Exotics Detector at the Large Hadron Collider (<a href="http://moedal.web.cern.ch/">MoEDAL</a>) has taken up the search, but has found no monopoles to date. </p>
<p>As a result, magnetic monopole enthusiasts have turned their sights to explaining why we <em>haven’t</em> seen any monopoles. </p>
<p>If the current generation of particle accelerators have failed to detect a magnetic monopole, perhaps the mass of a monopole is simply greater than we are able to create at present. </p>
<p>Using theory, we can estimate the maximum possible mass for the magnetic monopole. Given what we already know about the structure of the universe, we can estimate that the monopole mass could be up to an enormous 10<sup>14</sup> TeV. </p>
<p>An object this massive may have been produced only in the very early stages of the universe after the Big Bang, before cosmic inflation began. If the universe cooled to a point that monopole creation was no longer energetically possible before expanding, perhaps the monopoles are out there. Just few and far between. The trick is to find one.</p><img src="https://counter.theconversation.com/content/57661/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>T'Mir Danger Julius does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Physicists have theorised about the existence of a magnetic monopole for decades, but we have yet to find one.T'Mir Danger Julius, Data Scientist, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.