tag:theconversation.com,2011:/us/topics/electromagnetic-waves-22652/articlesElectromagnetic waves – The Conversation2023-07-14T13:04:51Ztag:theconversation.com,2011:article/2092672023-07-14T13:04:51Z2023-07-14T13:04:51ZCurious Kids: can our brains sense electromagnetic waves?<figure><img src="https://images.theconversation.com/files/537088/original/file-20230712-24-dkt9zu.jpg?ixlib=rb-1.1.0&rect=0%2C594%2C6016%2C3413&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/boy-listens-retro-radio-dark-candle-2040156215">calzone.photography/Shutterstock</a></span></figcaption></figure><p><strong>Can our brains sense electromagnetic waves? – Taye, aged 10, London</strong></p>
<p><a href="https://www.bbc.co.uk/bitesize/guides/zdx4t39/revision/2">Electromagnetic waves</a> are packets of energy travelling all around us. Some of these waves have lots of energy, and some have less.</p>
<p>We call the lowest energy electromagnetic waves <a href="https://science.nasa.gov/ems/05_radiowaves">radio waves</a>. There’s a good chance radio waves are moving around you right now, shining out of wifi routers, laptops and mobile phones. </p>
<p>The most powerful electromagnetic waves are <a href="https://science.nasa.gov/ems/12_gammarays">gamma rays</a>, though you will never have had these anywhere near you unless you’ve spent time hanging around exploding stars or the inside of a nuclear reactor. </p>
<p>And there are some electromagnetic waves that we can actually see. This is <a href="https://science.nasa.gov/ems/09_visiblelight">visible light</a> – the light we can see all around us. </p>
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<img alt="Diagram of the electromagnetic spectrum" src="https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537071/original/file-20230712-15-pd0rg2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The electromagnetic spectrum, from low energy radio waves to high energy gamma rays.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/electromagnetic-spectrum-diagram-vector-illustration-765933061">VectorMine/Shutterstock</a></span>
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<p>Most electromagnetic waves around you just pass by without you ever noticing them, but some of them are perceived by your brain and form a very important part of your everyday experience of the world.</p>
<h2>Brain – and body</h2>
<p>But your brain can’t detect them on its own. Instead, it has to make sense of information about the electromagnetic waves that has been detected by other parts of your body.</p>
<p>A large part of the human brain is dedicated to making sense of a type of electromagnetic wave that we call “visible light”. This type of electromagnetic wave bounces off objects and into our eyes.</p>
<p>At the back of the <a href="https://www.nei.nih.gov/learn-about-eye-health/healthy-vision/how-eyes-work">human eye</a> there are millions of tiny cells that produce electrical signals when they are hit by an electromagnetic wave with a particular amount of energy. Some of these cells are designed to detect an amount of energy that we call the colour “red”. Others are specialised for another amount of energy that we call the colour “green”, or another that we call “blue”. </p>
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<img alt="Child looking at butterflies" src="https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537084/original/file-20230712-15-9g5770.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">
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<span class="caption">Visible light is a kind of electromagnetic wave that cells in our eyes can detect – and is how we see the world around us.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/curly-girl-looking-butterfly-on-wild-774194680">Yuliya Evstratenko/Shutterstock</a></span>
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<p>The eye then sends electrical signals to your brain to describe the type of electromagnetic wave that it has detected – what colour the light was and where it came from. Finally, through a tremendously complicated sequence of electrical signals, a sighted person has the experience of “seeing”. </p>
<p>The fact that human eyes can detect visible light but not other types of electromagnetic wave is just the way that human eyes have evolved. Other animals’ eyes have evolved differently. For example, butterflies can see a <a href="https://doi.org/10.1113%2FJP273917">slightly higher energy</a> electromagnetic wave that our eyes can’t detect, but which we call <a href="https://science.nasa.gov/ems/10_ultravioletwaves">ultraviolet</a>. Some flowers reflect a lot of <a href="https://theconversation.com/the-secret-ultraviolet-colours-of-sunflowers-attract-pollinators-and-preserve-water-175723">ultraviolet waves</a>, which makes it easier for butterflies to find them for food.</p>
<h2>Invisible waves</h2>
<p>Another type of electromagnetic wave that our brain indirectly perceives is called <a href="https://science.nasa.gov/ems/07_infraredwaves">infrared</a>. We can sense this as heat.</p>
<p>When you stand near to a bonfire, your skin detects the fire’s infrared electromagnetic waves. It then sends electrical signals to the brain to tell it that there is something hot nearby. The brain couldn’t detect this wave by itself. </p>
<p>But the human body has no way to <a href="https://illumin.usc.edu/catch-a-wave-radio-waves-and-how-they-work/">detect radio waves</a>, so our brain is completely unaware of them as they pass around us. But we can use technology – like a radio, or wifi – to convert the electrical energy in radio waves into something we can detect, such as the music playing on a radio station. </p>
<p>We also use technology to detect <a href="https://science.nasa.gov/ems/11_xrays">x-rays</a>, another type of electromagnetic wave. X-rays are used in hospitals to look inside bodies – for instance, to see if a bone is broken. If you have an x-ray taken, hospital specialists send the <a href="https://www.nhs.uk/conditions/x-ray/">x-rays through your body</a>, and a machine can pick up how easily the x-rays travelled through different parts of your body. Areas that are more difficult for the x-ray to pass through, such as bone, show up as white. </p>
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<img alt="" src="https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282267/original/file-20190702-126345-1np1y7m.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/au/topics/curious-kids-36782">Curious Kids</a> is a series by <a href="https://theconversation.com/uk">The Conversation</a> that gives children the chance to have their questions about the world answered by experts. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskids@theconversation.com">curiouskids@theconversation.com</a> and make sure you include the asker’s first name, age and town or city. We won’t be able to answer every question, but we’ll do our very best.</em></p>
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<p>Even though your brain is ridiculously clever, it would know nothing without the information that it receives from the rest of your body. You and all your experiences come from your body, your organs, and your senses detecting the world around you, and sending that information to your brain. </p>
<p>An enormously complicated set of tiny electrical signals later and you have a conscious experience of being you, inside your body, and in a world literally full of electromagnetic waves.</p><img src="https://counter.theconversation.com/content/209267/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Damian Cruse 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>Your brains can perceive some electromagnetic waves – but not without your body’s help.Damian Cruse, Associate Professor in the School of Psychology, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1753062022-01-25T13:28:14Z2022-01-25T13:28:14ZHow 5G puts airplanes at risk – an electrical engineer explains<figure><img src="https://images.theconversation.com/files/442368/original/file-20220124-13-p8az99.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1563%2C875&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The FAA raised concerns that new, full-speed 5G cellphone services near airports could interfere with aircraft operations.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/44073224@N04/28345407183/">Bernal Saborio/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>New high-speed cellphone services have raised concerns of interference with aircraft operations, particularly as aircraft are landing at airports. The Federal Aviation Administration has <a href="https://www.faa.gov/5g">assured Americans that most commercial aircraft are safe</a>, and AT&T and Verizon have agreed to <a href="https://www.npr.org/2022/01/18/1073859389/verizon-att-5g-rollout-delay-airports-airlines-faa">hold off on installing their new cellphone antennas</a> near airports for six months. But the problem has not been entirely resolved.</p>
<p>Concerns began when the U.S. government <a href="https://docs.fcc.gov/public/attachments/DOC-370267A1.pdf">auctioned</a> part of the <a href="https://www.cnn.com/2022/01/19/tech/c-band-5g-att-verizon-rollout/index.html">C-band spectrum</a> to wireless carriers in 2021 for US$81 billion. The carriers are using C-band spectrum to <a href="https://theconversation.com/what-is-5g-an-electrical-engineer-explains-173196">provide 5G</a> service at full speed, 10 times the speed of 4G networks.</p>
<p>The C-band spectrum is close to the frequencies used by key electronics that aircraft rely on to land safely. Here’s why that can be a problem.</p>
<h2>Keeping order on the spectrum</h2>
<p>Wireless signals are carried by radio waves. The radio spectrum ranges from 3 hertz to 3,000 gigahertz and is part of the electromagnetic spectrum. The portion of the radio spectrum that carries the signals from your phone and other wireless devices is <a href="https://www.ctia.org/news/what-is-spectrum-a-brief-explainer">20 kilohertz to 300 gigahertz</a>.</p>
<p>If two wireless signals in the same area use the same frequency, you get garbled noise. You hear this when you are midway between two radio stations using the same or similar frequency bands to send their information. The signals get garbled and sometimes you hear one station, at other times the other, all mixed with a healthy dose of noise. </p>
<p>Therefore, in the U.S., the use of these frequency bands is tightly regulated by the Federal Communications Commission to ensure that radio stations, wireless carriers and other organizations are assigned “lanes,” or frequency spectra, to use in an orderly fashion.</p>
<h2>Bouncing radio waves off the ground</h2>
<p>Modern airplanes use altimeters, which calculate the time it takes for a signal to bounce back from the ground to determine a plane’s altitude. These altimeters are a vital part of automatic landing systems that are especially useful in cases where there is low visibility. </p>
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<a href="https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A hand on an aircraft yoke in front of a multicolor display panel" src="https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/442379/original/file-20220124-23335-w6fct0.jpg?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>
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<span class="caption">The radio altimeter in an aircraft tells the pilot how far off the ground the aircraft is.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/AustraliaMalaysiaPlane/6fb7b6c1d681451e988f5f9efad4205b/photo">AP Photo/Rob Griffith</a></span>
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<p>So, if an altimeter interprets a signal from a wireless carrier as the rebounded signal from the ground, it may think that the ground is closer than it is and prematurely try to lower the landing gear and do the other maneuvers that are needed to land an aircraft. If interference with wireless carrier signals corrupts and garbles the altimeter’s radio signals, the altimeter may not recognize the rebounded signal and thus be unable to figure out how close to the ground the plane is.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://memberservices.theconversation.com/newsletters/?nl=science&source=inline-science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p>
<p>The portions of the radio frequency spectrum used by airplanes and cellphone carriers are different. The problem is that airplane altimeters use the 4.2 to 4.4 gigahertz range, while the recently sold – and previously unused – C-band spectrum for wireless carriers ranges from 3.7 to 3.98 gigahertz. It turns out the 0.22 gigahertz difference between the signals may not be quite enough to be absolutely sure that a cellphone carrier signal will not be mistaken for or corrupt an altimeter’s signal.</p>
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<span class="caption">Full-speed 5G signals like those in services that wireless carriers are currently rolling out might interfere with aircraft altimeters.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/VirusOutbreak5GConspiracyTheories/71c36ff2fca14b4baf1ee83fda44af00/photo">AP Photo/Alastair Grant</a></span>
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<h2>Steering clear of trouble – for now</h2>
<p>The telecommunication industry has argued that the gap of 0.22 gigahertz is enough and <a href="https://apnews.com/article/why-are-airlines-worried-about-5g-f908b6eff8551b580dfd111029c5be2d">there will be no interference</a>. The airline industry has been <a href="https://www.npr.org/2022/01/07/1071409710/airlines-are-concerned-5g-wireless-service-may-affect-the-ability-to-land-planes">more cautious</a>. Even if the risk is very small, I believe the consequences of a plane crash are enormous.</p>
<p>Who is correct? The chances of such interference are very small, but the truth is that there isn’t much data to say that such interference will never happen. Whether there will be interference depends on the receivers in the altimeters and their sensitivity. In my view, there is no way to ensure that such stray interfering signals will never reach altimeters. </p>
<p>If the altimeters can register the stray signals as noise and filter them out, then they can function correctly. Upgrading aircraft altimeters <a href="https://www.cnn.com/2022/01/22/tech/5g-airlines-crisis-what-happened/index.html">is a costly proposition</a>, however, and it’s not clear who would pay the cost.</p>
<p>The FAA has been testing altimeters and <a href="https://arstechnica.com/tech-policy/2022/01/airline-ceos-make-u-turn-now-say-5g-isnt-a-big-problem-for-altimeters/">clearing ones that can be relied on</a> in the near future. AT&T and Verizon have agreed to not put up 5G transmitters and receivers near the 50 largest airports for six months while a solution is being worked out. This has averted a major crisis in the near term, but it isn’t a permanent solution. </p>
<p>Moreover, regional airlines and rural airports <a href="https://www.cnn.com/2022/01/20/business/faa-5g-airliner-approvals/index.html">remain at risk of interference</a>.</p><img src="https://counter.theconversation.com/content/175306/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Prasenjit Mitra works with Remcom Inc. He does not receive any funding from them. </span></em></p>Airplanes use radio waves to determine how far off the ground they are. New 5G cellphone services come close to the same frequencies the airplanes use. Here’s how that can be a problem.Prasenjit Mitra, Professor of Information Sciences and Technology, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1673182021-09-17T12:43:13Z2021-09-17T12:43:13ZDirected energy weapons shoot painful but non-lethal beams – are similar weapons behind the Havana syndrome?<figure><img src="https://images.theconversation.com/files/421671/original/file-20210916-29-4baj0e.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C1684%2C1053&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A television reporter reacts to being hit by a heat ray during a demonstration of the U.S. military's Active Denial System.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/television-reporter-reacts-as-he-is-targeted-with-the-news-photo/141136590">Paul J. Richards/AFP via Getty Images</a></span></figcaption></figure><p>The latest episodes of so-called <a href="https://www.bbc.com/news/world-58396698">Havana syndrome</a>, a series of unexplained ailments <a href="https://www.newyorker.com/magazine/2021/05/31/are-us-officials-under-silent-attack">afflicting U.S. and Canadian diplomats and spies</a>, span the globe. They include <a href="https://www.nbcnews.com/politics/politics-news/two-u-s-diplomats-be-evacuated-vietnam-after-havana-syndrome-n1277539">two diplomats in Hanoi, Vietnam</a> - which disrupted Vice President Kamala Harris’s foreign travel schedule - in August, <a href="https://www.reuters.com/world/europe/austria-investigating-reported-havana-syndrome-cases-among-us-envoys-2021-07-17/">several dozen</a> reports at the U.S. Embassy in Vienna earlier this year, and a <a href="https://www.cnn.com/2021/05/17/politics/us-investigates-second-case-mystery-syndrome-white-house/index.html">pair of incidents</a> at the White House last November.</p>
<p>The cause of these incidents is unknown, but speculation in the U.S. centers on electromagnetic beams.</p>
<p>If Havana syndrome turns out to be caused by weapons that shoot energy beams, they won’t be the first such weapons. As an <a href="https://scholar.google.co.uk/citations?user=0vO6w7MAAAAJ&hl=en">aerospace engineer</a> and former Vice Chair of the U.S. Air Force Scientific Advisory Board, I’ve researched directed energy. I can also personally attest to the effectiveness of directed energy weapons.</p>
<p>In 2020, <a href="http://nap.edu/25889">a study on Havana syndrome by the U.S. National Academies of Sciences, Engineering and Medicine</a> concluded that the more than 130 victims experienced some real physical phenomena, and that the cause was most likely some form of electromagnetic radiation. These incidents began in 2016 with reports of multiple personnel at the <a href="https://www.bbc.com/news/world-58396698">U.S. embassy in Havana, Cuba,</a> experiencing alarming and unexplained symptoms. The symptoms included a feeling of pressure on the face, loud noises, severe headaches, nausea and confusion. In some cases, the victims seem to have been <a href="https://www.politico.com/news/2021/05/12/trump-havana-syndrome-probe-487716">left with permanent health effects</a>.</p>
<p>Scientists from Cuba’s Academy of Sciences issued a <a href="https://apnews.com/article/science-cuba-havana-physics-4316989d278ae353c42ef78033d9b2a5">report refuting the U.S. National Academies report</a> and ascribing the reported symptoms to psychological effects or a range of ordinary ailments and preexisting conditions. But based on my own experience, directed energy appears to be a plausible explanation.</p>
<p>Here’s how these beams affect people.</p>
<h2>At the right wavelength</h2>
<p>There is a very wide range of <a href="https://science.nasa.gov/ems/01_intro">electromagnetic waves that are characterized by wavelength</a>, which is the distance between successive peaks. These waves can interact with different types of matter, including human bodies, in a variety of ways. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a colorful chart with six aligned rows" src="https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421686/original/file-20210916-15-1b3w5bo.jpg?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"></a>
<figcaption>
<span class="caption">The electromagnetic spectrum spans radio waves to gamma waves.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:EM_Spectrum3-new.jpg">NASA</a></span>
</figcaption>
</figure>
<p>At short wavelengths, a few hundred-billionths of a meter, ultraviolet rays from the Sun can burn the skin’s surface if someone is exposed for too long. Microwaves have longer wavelengths. People use these every day to reheat meals. Microwaves <a href="https://www.scientificamerican.com/article/how-does-a-microwave-oven/">transfer energy</a> into the water molecules inside food.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Dark green four-wheel truck with large octagonal antenna mounted on the roof" src="https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=671&fit=crop&dpr=1 600w, https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=671&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=671&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=844&fit=crop&dpr=1 754w, https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=844&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/421202/original/file-20210914-17-a0zt0j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=844&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 U.S. military has developed an Active Denial System that aims microwaves at people to cause pain without injury.</span>
<span class="attribution"><a class="source" href="https://www.kirtland.af.mil/News/Photos/igphoto/2000429585/">U.S. Air Force</a></span>
</figcaption>
</figure>
<p>The U.S. military has developed <a href="https://jnlwp.defense.gov/Press-Room/Fact-Sheets/Article-View-Fact-sheets/Article/577989/active-denial-technology/">a directed energy technology</a> that shoots beams of a slightly longer wavelength in a focused area over distances up to a mile. This directed energy technology was designed for nonlethal control of crowds. When these waves interact with a person, they pass through the skin and transfer energy to the water that lies just under the surface.</p>
<p>I had the opportunity to be zapped by one of these systems. I stood about a half-mile from the source and the beam was turned on. The portion of my body exposed to the beam got hot really quickly, and I immediately stepped out of the beam. The feeling was as though someone had just opened the door of a large furnace right by me. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/LVvX6jvD8UA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A demonstration of a military Active Denial System.</span></figcaption>
</figure>
<p>At even longer wavelengths, electromagnetic radiation can <a href="https://theconversation.com/scientists-suggest-us-embassies-were-hit-with-high-power-microwaves-heres-how-the-weapons-work-151730">interact with electronic systems</a> and can be used to disable computers and control systems. For these waves, interaction with matter generates electrical currents and fields that interfere with the electrical systems. The military is developing these technologies to <a href="https://www.popsci.com/story/technology/air-force-anti-drone-technology-thor/">defend against drone attacks</a>.</p>
<h2>Defense through detection</h2>
<p>It’s plausible that at just the right wavelength, an electromagnetic beam could be projected over hundreds of yards to create the symptoms seen in Havana syndrome incidents. If this is the case, it’s likely that these beams are interfering with the electrical functions of the brain and central nervous system. </p>
<p>For example, the <a href="https://doi.org/10.1152/jappl.1962.17.4.689">Frey effect</a> involves microwaves activating the auditory sensory nerves. Other studies have noted potential <a href="https://doi.org/10.1186/s40779-017-0139-0">effects of microwaves on the central nervous system</a>, such as decreased response time, social dysfunction and anxiety. </p>
<p>Further study is needed to determine the cause of Havana syndrome incidents. Unfortunately, this type of electromagnetic radiation does not leave a telltale trace like sunburn, which makes it difficult to be certain of the explanation. </p>
<p>While the results of the National Academies study were made public, it is likely that federal agencies are carrying out additional activities behind the scenes to try to explain these incidents and determine who is to blame. Similar to responding to cyberattacks, though, the government may be reluctant to release too much information to the public because it could reveal techniques for detecting and countering the attacks.</p>
<p>If the source of Havana syndrome turns out to be electromagnetic waves, then in principle, buildings could be hardened against them. However, it would be expensive and would still leave people vulnerable outdoors. Perhaps the best option to prevent further attack is detection. It is relatively simple and inexpensive to install sensors to detect electromagnetic waves on buildings and vehicles. Such sensors could also help identify the location of the source of the attacks and, in this way, act as a deterrent. </p>
<p>Assuming Havana syndrome is the result of deliberately targeted electromagnetic beams, employees of the U.S. government and other nations will remain susceptible to these attacks until governments take such defensive measures.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</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-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/167318/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Iain Boyd receives funding from the U.S. Department of Defense, the U.S. Department of Energy, NASA, Lockheed-Martin Corporation, Northrop-Grumman Corporation, L3-Harris Corporation.</span></em></p>Electromagnetic beams of the right power and wavelength can cause pain and zap electronics. Could they also be used to disrupt a person’s nervous system?Iain Boyd, Professor of Aerospace Engineering Sciences, University of Colorado BoulderLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1481562021-01-12T13:19:48Z2021-01-12T13:19:48ZHow does Wi-Fi work? An electrical engineer explains<figure><img src="https://images.theconversation.com/files/375990/original/file-20201218-17-1tmdcia.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C4985%2C3735&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Wi-Fi symbol, like the technology it represents, has become ubiquitous.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/close-up-of-an-outdoor-wifi-antenna-integrated-into-a-news-photo/1090961462?adppopup=true">Smith Collection/Gado via Getty Images</a></span></figcaption></figure><p>Though you can’t see them, radio waves are all around you all the time, carrying information. For most people, some of those radio waves are Wi-Fi signals. Wi-Fi is the catchy name an <a href="https://boingboing.net/2005/11/08/wifi-isnt-short-for.html">industry alliance came up</a> with to market devices that transmit large amounts of data over short distances using radio waves. The letters don’t stand for anything.</p>
<p>Wi-Fi, like broadcast radio and cellular telephone signals, is based on scientific discoveries dating back to the late 19th century. When electrons moving through a wire are made to alternate directions periodically, something magical happens. Electrons in another wire, located at a distance, start to move up and down in sync, as though they were telepathically connected.</p>
<p>This phenomenon was first observed by <a href="https://www.aaas.org/heinrich-hertz-and-electromagnetic-radiation">Heinrich Hertz</a> in 1887, confirming a mathematical theory proposed by <a href="https://physicsworld.com/a/james-clerk-maxwell-a-force-for-physics/">James Clerk Maxwell</a> in 1864. Maxwell’s elegant theory explains how the alternating current in the first wire causes a “radio wave” of alternating electrical and magnetic fields to radiate out in all directions at the speed of light. The wave, in turn, causes an alternating current in the second wire. </p>
<p>The <a href="https://science.nasa.gov/ems/01_intro">electromagnetic spectrum</a> includes visible light, which alternates at a much higher frequency than radio waves. There is a mystery to ponder here: Human bodies have evolved to see light but not radio waves. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Back of a small home internet router with Wi-Fi antenna, ethernet ports and ethernet cables" src="https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375991/original/file-20201218-21-1jr10q3.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">This little antenna transmits radio waves throughout an apartment-size area.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/internet-connection-with-wlan-router-in-home-office-royalty-free-image/184999273?adppopup=true">deepblue4you/E+ via Getty Images</a></span>
</figcaption>
</figure>
<h2>Wireless 0’s and 1’s</h2>
<p>Traditional AM/FM radio and TV broadcasts communicate information through analog, or continuous, signals. Wi-Fi communicates information digitally, as discrete values – the 0’s and 1’s of binary data. This lets mobile devices easily send a wide range of data types, including video, image, speech and text. Digitally formatted data is also easier to compress for faster download, to encode for preventing errors and to encrypt for ensuring confidentiality.</p>
<p>When you search for something online, data from your Wi-Fi device is first communicated over radio waves to a Wi-Fi access point, which could be the antenna on the back of your home internet router or a Wi-Fi antenna in a café. It then travels over wired cables to a gateway device operated by your broadband internet provider. From there, the query finds its way across multiple wired links to Google’s server. The response comes back through a similar path in reverse. </p>
<p>Wi-Fi devices made by different companies can talk to each other. This is because they follow a common set of rules called the <a href="https://www.networkworld.com/article/3238664/80211x-wi-fi-standards-and-speeds-explained.html">802.11 standards</a>, published by the Institute for Electrical and Electronic Engineers, the IEEE. These rules specify how 0’s and 1’s are represented using radio waves and how devices identify themselves. They also specify an algorithm for how and when to talk, called <a href="https://www.geeksforgeeks.org/carrier-sense-multiple-access-csma/">carrier-sense multiple access</a>, or CSMA. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="View from a balcony down into a busy café where most people are looking at their phones" src="https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/375821/original/file-20201217-13-1xacvqv.jpg?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">The key to making Wi-Fi practical is in how it juggles multiple people using it at once.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/d1ngW7SNehM">The Creative Exchange/Unsplash</a></span>
</figcaption>
</figure>
<p>CSMA makes Wi-Fi devices both polite and smart. They always listen before they talk, to check that no other nearby devices are transmitting. To further minimize talking at the same time, they roll dice to pick random times to transmit. And when there are more devices around, they speak less often. All of this happens too quickly to notice.</p>
<p>[<em><a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=experts">Expertise in your inbox. Sign up for The Conversation’s newsletter and get expert takes on today’s news, every day.</a></em>]</p>
<h2>Fast, but not always strong</h2>
<p>You may sometimes have trouble connecting to a Wi-Fi access point. Here is why: Radio signals get weaker with distance. Thick walls, metal shelves and even an aquarium can weaken and obstruct radio waves. If the signal gets too weak, there is poor or no communication. If there are too many Wi-Fi networks nearby, they may also interfere with your link. </p>
<p>Several improved versions of Wi-Fi have emerged since it first appeared in the mid-1990s. Its <a href="https://www.lifewire.com/how-fast-is-a-wifi-network-816543">maximum data rate</a> – several billion bits per second – is now more than a thousand times higher than the earliest version. This is why we can have video conference calls over Wi-Fi today.</p>
<p>Emerging applications like virtual reality gaming demand ever-higher download speeds. They are likely to drive even further improvements in Wi-Fi.</p><img src="https://counter.theconversation.com/content/148156/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bhaskar Krishnamachari receives funding from NSF and DARPA. </span></em></p>Wi-Fi has become a fundamental part of modern digital life, but its foundation is the same as the technology that allowed your great-grandparents to listen to their favorite radio programs.Bhaskar Krishnamachari, Professor of Electrical Engineering, University of Southern CaliforniaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/883722017-11-30T08:27:18Z2017-11-30T08:27:18ZOur exposure to electromagnetic waves: beware of commonly held beliefs<figure><img src="https://images.theconversation.com/files/196994/original/file-20171129-12035-1lwxr6a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A base station or GSM relay antenna on a roof in Paris.</span> <span class="attribution"><span class="source">Pyb/Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/123575/original/image-20160523-11010-17x91o4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/123575/original/image-20160523-11010-17x91o4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=305&fit=crop&dpr=1 600w, https://images.theconversation.com/files/123575/original/image-20160523-11010-17x91o4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=305&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/123575/original/image-20160523-11010-17x91o4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=305&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/123575/original/image-20160523-11010-17x91o4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=383&fit=crop&dpr=1 754w, https://images.theconversation.com/files/123575/original/image-20160523-11010-17x91o4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=383&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/123575/original/image-20160523-11010-17x91o4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=383&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><em>This article is published in partnership with “La Tête au carré”, the daily radio show on France Inter dedicated to the popularisation of science, presented and produced by Mathieu Vidard. The author of this text, Joe Wiart, discussed his research on the show broadcast on April 28, 2017 accompanied by Aline Richard, Science and Technology Editor for The Conversation France.</em></p>
<hr>
<p>For over 10 years, controlling exposure to electromagnetic waves and to <a href="https://en.wikipedia.org/wiki/Radio_frequency">radio frequencies</a> in particular has fuelled many debates, which have often been quite heated. An analysis of reports and scientific publications devoted to this topic shows that researchers are mainly studying the possible impact of mobile phones on our health. At the same time, according to what has been published in the media, the public is mainly concerned about base stations. Nevertheless, mobile phones and wireless communication systems in general are widely used and have dramatically changed how people around the world communicate and work.</p>
<p>Globally, the number of mobile phone users now exceeds 5 billion. And according to the findings of an Insee study, the percentage of individuals aged 18-25 in France who own a mobile phone is 100%! It must be noted that the use of this method of communication is far from being limited to simple phone calls – by 2020 global mobile data traffic is expected to represent four times the overall Internet traffic of 2005. In France, according to the French regulatory authority for electronic and postal communications (<a href="http://www.arcep.fr/index.php?id=13287">ARCEP</a>), over 7% of the population connected to the Internet exclusively via smartphones in 2016. And the skyrocketing use of connected devices will undoubtedly accentuate this trend.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/165258/original/image-20170413-25901-vdj0wr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/165258/original/image-20170413-25901-vdj0wr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=569&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165258/original/image-20170413-25901-vdj0wr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=569&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165258/original/image-20170413-25901-vdj0wr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=569&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165258/original/image-20170413-25901-vdj0wr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=716&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165258/original/image-20170413-25901-vdj0wr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=716&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165258/original/image-20170413-25901-vdj0wr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=716&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Smartphone zombies.</span>
<span class="attribution"><span class="source">Ccmsharma2/Wikimedia</span></span>
</figcaption>
</figure>
<p>The differences in perceptions of the risks associated with mobile phones and base stations can be explained in part by the fact that the two are not seen as being related. Moreover, while exposure to electromagnetic waves is considered to be “voluntary” for mobile phones, individuals are often said to be “subjected” to waves emitted by base stations. This helps explains why, despite the widespread use of mobiles and connected devices, the deployment of base stations remains a hotly debated issue, often focusing on health impacts.</p>
<p>In practice, national standards for limiting exposure to electromagnetic waves are based on the recommendations of the <a href="http://www.icnirp.org/">International Commission on Non-Ionizing Radiation Protection</a> (ICNIRP) and on scientific expertise. A number of studies have been carried out on the potential effects of electromagnetic waves on our health. Of course, research is still being conducted in order to keep pace with the constant advancements in wireless technology and its many uses. This research is even more important since radio frequencies from mobile telephones have now been classified as “possibly carcinogenic for humans” (group 2B) following a review conducted by the <a href="https://www.iarc.fr/indexfr.php">International Agency for Research on Cancer</a>.</p>
<p>Given the great and ever-growing number of young people who use smartphones and other mobile devices, this heightened vigilance is essential. In France the National Environmental and Occupational Health Research Programme (PNREST) of the National Agency for Food, Environmental and Occupational Health Safety (Anses) is responsible for monitoring the situation. And to address public concerns about base stations (of which there are 50,000 located throughout France), many municipalities have discussed charters to regulate where they may be located. Cities such as Paris, which, striving to set an example for France and major European cities, signed such a charter as of 2003, are officially limiting exposure from base stations through a signed agreement with France’s three major operators.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/165259/original/image-20170413-25888-z942rx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/165259/original/image-20170413-25888-z942rx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=802&fit=crop&dpr=1 600w, https://images.theconversation.com/files/165259/original/image-20170413-25888-z942rx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=802&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/165259/original/image-20170413-25888-z942rx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=802&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/165259/original/image-20170413-25888-z942rx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1008&fit=crop&dpr=1 754w, https://images.theconversation.com/files/165259/original/image-20170413-25888-z942rx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1008&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/165259/original/image-20170413-25888-z942rx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1008&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Hillside in Miramont, Hautes Pyrenees, France.</span>
<span class="attribution"><span class="source">Florent Pécassou/Wikimedia</span></span>
</figcaption>
</figure>
<p>This charter was updated in 2012 and was further discussed at the Paris Council in March, in keeping with the <a href="https://www.anfr.fr/controle-des-frequences/exposition-du-public-aux-ondes/le-role-des-maires/la-loi-abeille/">Abeille law</a>, which was proposed to the National Assembly in 2013 and passed in February 2015, focusing on limiting the exposure to electromagnetic fields. Yet it is important to note that this initiative, like so many others, concerns only base stations despite the fact that exposure to electromagnetic waves and radio frequencies comes from many other sources. By focusing exclusively on these base stations, the problem is only partially resolved. Exposure from mobile phones for users or their neighbours must also be taken into consideration, along with other sources.</p>
<p>In practice, the portion of exposure to electromagnetic waves which is linked to base stations is far from representing the majority of overall exposure. As many studies have demonstrated, exposure from mobile phones is much more significant. Fortunately, the deployment of 4G, followed by 5G, will not only improve speed but will also contribute to significantly reducing the power radiated by mobile phones. Small cell network architecture with small antennas supplementing larger ones will also help limit radiated power. It is important to study solutions resulting in lower exposure to radio frequencies at different levels, from radio devices to network architecture or management and provision of services. This is precisely what the partners in the <a href="http://www.lexnet.fr/projet-presentation.html">LEXNET</a> European project set about doing in 2012, with the goal of cutting public exposure to electromagnetic fields and radio frequency in half.</p>
<p>In the near future, fifth-generation networks will use several frequency bands and various architectures in a dynamic fashion, enabling them to handle both increased speed and the proliferation of connected devices. There will be no choice but to effectively consider the network-terminal relationship as a duo, rather than treating the two as separate elements. This new paradigm has become a key priority for researchers, industry players and public authorities alike. And from this perspective, the latest discussions about the location of base stations and renewing the Paris charter prove to be emblematic.</p>
<hr>
<p><em>This article was translated from the French by <a href="https://blogrecherche.wp.imt.fr/en/2017/07/11/electromagnetic-waves-popular-belief/">I'MTech</a>.</em></p><img src="https://counter.theconversation.com/content/88372/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joe Wiart has received financing from ANSES, ANFr, ANR and Europe to conduct studies on evaluating the impact of exposure to radio-frequency signals. </span></em></p>Is it necessary to control exposure to electromagnetic waves by limiting the number of relay antennas? Yes, but that’s not the only thing.Joe Wiart, Titulaire de la Chaire C2M de l'institut Mines Telecom, Télécom Paris – Institut Mines-TélécomLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/706362016-12-20T20:15:26Z2016-12-20T20:15:26ZWhy you can’t fry eggs (or testicles) with a cellphone<figure><img src="https://images.theconversation.com/files/151083/original/image-20161220-26741-nmhzbw.jpg?ixlib=rb-1.1.0&rect=721%2C0%2C3197%2C1982&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pocket your phone without worry.</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/pic.mhtml?id=533966416">Phone image via www.shutterstock.com.</a></span></figcaption></figure><p>A minor craze in men’s underwear fashions these days seems to be <a href="http://www.nbcnews.com/news/world/boxer-shorts-claim-protect-testicles-cellphone-radiation-n538576">briefs that shield the genitals</a> from cellphone radiation. The sales claim is that these products protect the testicles from the harmful effects of the radio waves emitted by cellphones, and therefore help maintain a robust sperm count and high fertility. These undergarments may shield the testicles from radiation, but do <a href="http://www.newsweek.com/boxer-rebellion-pocketed-cellphone-may-be-behind-your-infertility-287075">male cellphone users really risk infertility</a>?</p>
<p>The notion that electromagnetic radiation in the radio frequency range can cause male sterility, either temporary or permanent, has been around for a long time. As I describe in my book <a href="http://press.princeton.edu/titles/10691.html">“Strange Glow: The Story of Radiation</a>,” during World War II some enlisted men would consistently and inexplicably volunteer for radar duty just prior to their scheduled leave days. It turned out that a rumor had been circulating that exposure to radio waves from the radar equipment produced temporary sterility, which the soldiers saw as an employment benefit.</p>
<p>The military wanted to know whether there was any substance to the sterility rumor. So they asked <a href="https://www.nobelprize.org/nobel_prizes/medicine/laureates/1946/muller-bio.html">Hermann Muller</a> – a geneticist who <a href="https://www.nobelprize.org/nobel_prizes/medicine/laureates/1946/muller-lecture.html">won the Nobel Prize</a> for showing that x-rays could cause sterility and genetic mutations – to evaluate the effects of radio waves in the same fruit fly experimental model he had used to show that x-rays impaired reproduction. </p>
<p>Muller could find no dose of radio waves that produced either sterility or genetic mutations, and concluded that radio waves did not present the same threat to fertility that x-rays did. Radio waves were different. But why? Aren’t both x-rays and radio waves <a href="http://www.livescience.com/38169-electromagnetism.html">electromagnetic radiation</a>?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=326&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=326&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=326&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=410&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=410&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151022/original/image-20161220-26741-1sutwex.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=410&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 electromagnetic spectrum, tiny wavelengths on the left, longer wavelengths on the right.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:EM_Spectrum_Properties_reflected.svg">Inductiveload</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Yes, they are – but they differ in one key factor: They have very different wavelengths. All electromagnetic radiation travels through space as invisible waves of energy. And it’s the specific wavelength of the radiation that determines all of its effects, both physical and biological. The shorter wavelengths carry higher amounts of energy than the longer wavelengths.</p>
<p>X-rays are able to damage cells and tissues precisely because their wavelengths are extremely short – one-millionth the width of a human hair – and thus are highly energetic and very harmful to cells. Radio waves, in contrast, carry little energy because their wavelengths are very long – about the length of a football field. Such long-wavelength radiations have really low energies – too low to damage cells. And it’s this big difference between the wavelengths of x-rays and radio waves that the infertility theorists fail to recognize.</p>
<p>X-rays, and other high-energy waves, produce sterility by killing off the testicular cells that make sperm – the “<a href="https://www.repropedia.org/spermatogonium">spermatogonia</a>.” And x-ray doses must be extremely high to kill enough cells to produce sterility. Still, even when the doses are high, the sterility effect is usually temporary because the surviving spermatogonia are able to <a href="http://doi.org/10.1002/aja.1001180211">spawn replacements</a> for their dead comrades, and sperm counts typically return to their normal levels within a few months.</p>
<p>So, if high doses of highly energetic x-rays are needed to kill enough cells to produce sterility, how can low doses of radio waves with energies too low to kill cells do it? Good question.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/axUBeF-W7II?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Don’t fall for the phone-cooking-egg hoax.</span></figcaption>
</figure>
<p>At this point you may be thinking that you’ve seen videos of <a href="https://www.youtube.com/watch?v=axUBeF-W7II">cellphones cooking eggs</a>. And you’ve even experienced your cellphone getting pretty warm when it’s used heavily. But this doesn’t show that cellphones put out a lot of radiation energy. The cooked egg video is a prank, and the phone gets hot because of the heat generated by the chemical reactions going on within the battery, not from radio waves.</p>
<p>Still you protest: What about those sporadic reports claiming that cellphones suppress sperm counts? For the moment, that’s all they are – sporadic reports, unconfirmed by other investigators. You can find all kinds of random assertions about the effects of radiation on health, both <a href="http://www.orau.org/ptp/collection/quackcures/quackcures.htm">good</a> and <a href="https://www.scribd.com/document/59721111/TOP10-Myths-About-Radiation">bad</a>, most of which imply that there is some type of validated scientific evidence to support the claim. Why not believe all of them?</p>
<p>If we’ve learned anything over the years about scientific evidence, it’s that isolated findings from individual labs, reporting limited experimental data, do not a strong case make. Most of the very limited “scientific” reports of infertility caused by cellphones, often <a href="http://www.ewg.org/cell-phone-radiation-damages-sperm-studies-find">cited by anti-cellphone activists</a>, come from outside the radiation biology community, and are published in lower-tier journals of questionable quality. Few, if any, of these reports make any attempt at actually measuring the radiation doses received from the cellphones (probably because they lack either the expertise or the equipment required to do it).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=483&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=483&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151040/original/image-20161220-26748-1ive95i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=483&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Human sperm, unconcerned by what’s in your pocket.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Sperm_(265_33)_human.jpg">Doc. RNDr. Josef Reischig, CSc.</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>And none actually measure fertility rates – the health endpoint of concern – but rather measure sperm counts and other sperm quality parameters and then infer that there will be an impact on fertility. In fact, sperm counts can vary widely between normally fertile individuals and even within the same individual from day to day. For example, men who frequently ejaculate have lower sperm counts, as you might expect, because they are regularly jettisoning sperm. (Men who ejaculate daily can have <a href="http://doi.org/10.1186/s12958-015-0045-9">sperm counts 50 percent lower</a> than men who don’t.) Perhaps the allegedly lower sperm counts of cellphone users just means that they are having more sex!</p>
<p>But seriously, the point is this: There are so many things that can affect sperm counts in big ways that minor fluctuations in sperm counts have no practical impact on whether a man will produce babies, even if it were true that cellphones can modestly suppress sperm counts.</p>
<p>It is clear that these infertility claims are not the consensus of the mainstream scientific community – a community that demands more rigorous evidence. There are many excellent laboratories around the world that study radiation effects, and it isn’t difficult to study infertility in fruit flies, mice and even people. (It’s fairly easy to find men willing to <a href="https://verdict.justia.com/2012/01/24/men-who-give-it-away">donate sperm samples</a>.) If the sterility story were true, there would be a chorus of well-respected laboratories from around the world singing the cellphone infertility song, not just a few.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=666&fit=crop&dpr=1 600w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=666&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=666&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=837&fit=crop&dpr=1 754w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=837&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/151036/original/image-20161220-26748-eadyou.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=837&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Guglielmo Marconi, inventor of the radio.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/smithsonian/2551824648">Smithsonian Institution</a></span>
</figcaption>
</figure>
<p>The fact is, the current data suggesting that cellphones cause infertility are too weak to challenge the dogma of over 100 years of commercial experience with radio waves. Radio waves are not unique to cellphones. They have been used for telecommunication ever since <a href="http://www.history.com/this-day-in-history/marconi-sends-first-atlantic-wireless-transmission">Marconi first demonstrated in 1901</a> that they could carry messages across the entire Atlantic Ocean. Early radio workers received massive doses of radio waves, yet there is no indication they had any problems with their fertility. If they didn’t experience fertility problems with their high doses, how can the relatively low doses from cellphones have such an effect? Hard to understand.</p>
<p>Nevertheless, people can spend their money as they please and wear any underwear they want. But if you are still concerned about radio waves affecting your fertility, why not just carry your cellphone in your shirt pocket rather than your pants, and let your testicles be?</p><img src="https://counter.theconversation.com/content/70636/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Timothy J. Jorgensen 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>Did your holiday gift list include radiation-shielding undies to protect your privates from cellphone radio waves? A radiation expert explains they’re unnecessary – your phone won’t affect your fertility.Timothy J. Jorgensen, Director of the Health Physics and Radiation Protection Graduate Program and Associate Professor of Radiation Medicine, Georgetown UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/573402016-04-07T20:05:44Z2016-04-07T20:05:44ZTwisted light could dramatically boost internet speeds<figure><img src="https://images.theconversation.com/files/117780/original/image-20160407-13983-3puq0t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A new development could mean vastly increase data transfer over optical fibre cables.</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p><a href="http://www.explainthatstuff.com/fiberoptics.html">Fibre optics</a> allow for the communication of data at the speed of light.</p>
<p>But the amount of data that can be sent along any optic fibre is limited by how much information you can encode into the light wave travelling through it.</p>
<p>Currently, optic fibre technology uses several different properties of light to encode information, including brightness, colour, polarisation and direction of propagation. </p>
<p>But if we want to cram even more information through optic fibre, we need to use other features of light to encode more information, without disrupting currently used properties.</p>
<p>Such a feature could help boost the bandwidth of optic fibre technology, including our internet speeds. </p>
<h2>Detecting the twist</h2>
<p>If the light wave travelling through the optic fibre is twisted helically – like a spring – then it has angular momentum, which is a measure of its momentum when it rotates around a point.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/iWSu6U0Ujs8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A quick primer on angular momentum.</span></figcaption>
</figure>
<p>But there was a major problem with using angular momentum to decode the information from the optic fibre. We needed a material with tiny nanoscale helical structures that could detect the twisted light.</p>
<p>Our research, published today in <a href="http://science.sciencemag.org/lookup/doi/10.1126/science.aaf1112">Science</a>, shows how we can control the angular momentum of light at a nanoscale using an integrated photonic chip.</p>
<p>So for the first time, we have a chip with a series of elaborate nano-apertures and nano-grooves that allow for the on-chip manipulation of twisted light.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117765/original/image-20160407-13987-1junztc.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">The nanophotonic chip magnified 2,000 times. Each indentation on the image is a single unit of the chip, like a single pixel in a display panel, made up of semi-circle nano-grooves and nano-apertures engraved in a metallic film.</span>
<span class="attribution"><span class="source">RMIT University</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The helical design of these tiny apertures and grooves removes the need for any other bulky interference-based optics to detect the angular momentum signals.</p>
<p>So if you send an optical data signal to a photonic chip, which is a microchip that uses light instead of electrons, then it is important to know where the data is going, otherwise information will be lost.</p>
<p>Using our nanophotonic chip, we can precisely guide angular momentum data signals without losing the information they carry.</p>
<p>What’s more, the angular momentum information of many different signals can be processed at the same time through the chip.</p>
<p>This means we can potentially achieve an ultra-wide bandwidth, with six-orders magnitude of increased data access compared to current technology.</p>
<h2>Technology for today</h2>
<p>Owing to the rapid development of nano-fabrication technology, we believe there is no technical challenge to the mass production of this chip today.</p>
<p>This breakthrough opens an entirely new perspective in employing light for chip-scale information generation, transmission and retrieval of images, videos, sounds and so on.</p>
<p>It could be used in applications such as data transmission, ultra-high definition displays, ultra-high capacity optical communications and ultra-secure optical encryption.</p>
<p>For example, the communication speed on the National Broadband Network can be boosted through the parallel processing of the angular momentum.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/117766/original/image-20160407-13952-vj8k6t.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">Professor Min Gu with the nanophotonic chip that can harness the angular momentum of light.</span>
<span class="attribution"><span class="source">RMIT University</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Since the chip consists of an array of individually-controlled single units, and each single unit is capable of independently processing the angular momentum information, this chip device allows for parallel processing of optical information.</p>
<p>A large number of optical fibres in one fibre bundle can be processed through the chip in parallel, which means the processing speed can be significantly increased by considering how large the array is.</p>
<p>For example, if we take 100 by 100 of such units in the array for the chip, then the speed could be boosted by four orders of magnitude.</p>
<p>This quirk of physics could one day lead to significantly faster internet speeds along with a host of other useful applications.</p><img src="https://counter.theconversation.com/content/57340/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Min Gu receives funding from the Australian Research Council Laureate Fellowship program (FL100100099) and from the Australian Research Council Centre of Excellence for Ultrahigh-bandwidth Devices for Optical Systems (CUDOS) (project number CE110001018).</span></em></p><p class="fine-print"><em><span>Haoran Ren and Qiming Zhang 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>The design of a new chip to detect the twisted nature of light waves could pave the way for next generation of optical communication technologies.Min Gu, Associate Deputy Vice-Chancellor for Research Innovation and Entrepreneurship, RMIT UniversityHaoran Ren, PhD candidate, Swinburne University of TechnologyQiming Zhang, Senior Research Fellow, RMIT UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/545552016-03-01T19:04:18Z2016-03-01T19:04:18ZExplainer: making waves in science<figure><img src="https://images.theconversation.com/files/111888/original/image-20160218-1243-ky6bkp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Making waves.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/_imax/2644301036/">Flickr/Max Nathan</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>We see them at the beach. They’re behind every sound and light show and the miracle of Wi-Fi. And now, thanks to what’s being called the discovery of the century, they have opened a way of detecting distant black-hole collisions.</p>
<p>I’m talking, of course, about waves.</p>
<p>We wouldn’t have speech or ultrasound imaging without sound waves. Water waves are a surfer’s paradise. Electromagnetic waves make both vision and television possible, as well as Wi-Fi, chest X-rays and microwave ovens.</p>
<p>It is electrical waves, not electrons, that sweep down our wires and power lines at close to the speed of light (the actual electrons drift along behind, <a href="http://sciencequestionswithsurprisinganswers.org/2014/02/19/what-is-the-speed-of-electricity/">at less than a snail’s pace</a>!). </p>
<p>And the recent <a href="https://theconversation.com/gravitational-waves-discovered-the-universe-has-spoken-54237">discovery of gravitational waves</a> will open up a new frontier in astronomy.</p>
<h2>What’s in a wave?</h2>
<p>Waves are very different from particles. Waves have energy, but not mass. They love to diffract or spread out, not stay in fixed lumps.</p>
<p>When two waves meet they don’t bounce off each other: they just add and subtract as they pass through each other, and then carry on their ways as if they’d never met. This is called interference, and it makes waves highly unsuitable for snooker, but it is what lets many people use their mobile phones at the same time.</p>
<p>Water is a good example for thinking about the difference between waves and particles. Water can carry energy in two different ways. </p>
<p>First, it can flow from one place to another, such as from the river to the sea. In such a flow, each water molecule starts upstream and moves downstream. The flow is made up of particles.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/112121/original/image-20160219-21502-12gsfdc.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 ripples are waves in the water.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/scott-s_photos/7904846012/">Flickr/Scott Cresswell</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But imagine the ripples spreading out from a dropped pebble in a pond, or watching the waves spread out from the bow of a passing boat. These waves also carry energy as, for example, they rock floating sticks and even push them along a little. </p>
<p>But the water molecules that make up the shape of the ripple just after the pebble is dropped are completely different to the ones that make up the ever-spreading ripple five seconds later. Each water molecule stays roughly where it is, barring some jiggling, while the wave moves on. So water waves are not a flow of particles.</p>
<h2>So how do waves move?</h2>
<p>When that pebble is dropped in the pond, it pushes water out of the way. The water has nowhere to go but to the side and up, creating a circular peak around the drop point. This peak falls again, under the forces of gravity and surface tension, pushing the water beneath it out of the way.</p>
<p>On the inside of the circle, this newly pushed water fills the hole left by the pebble passing through. But on the outside, it creates a new circular peak, just a little further out.</p>
<p>So a ripple spreads out from the drop point even though the individual water molecules are mostly just moving up and down in place.</p>
<p>More generally, waves need something to wave in: a medium. Water, air, power lines and the electromagnetic field are all suitable media. Even spacetime itself will do, in the case of gravitational waves.</p>
<p>Waves are simply distortions moving through the medium. These distortions can be started off by many means: a dropped pebble, a shout, a radio transmitter or colliding black holes.</p>
<p>In each case, the medium has some degree of elasticity and responds to a distortion by trying to snap back into shape. But this distorts the neighbouring region, and so on, and so a wave is born. </p>
<p>The strength of the distortions is called the amplitude of the wave, and is closely related to its energy.</p>
<h2>Catching the perfect wave</h2>
<p>All waves, whether in water, air or spacetime, can come either in pulses, such as a sharp sound, or as a collection of ripples, such as at the beach. But no matter what shape and size, any wave can be thought of as made up of many perfect waves added together. </p>
<p>A perfect wave is what we hear when a singer holds a single beautiful note. It is a smooth series of peaks and troughs in the strength of the wave, with successive peaks all separated by the same distance: the wavelength. The number of peaks passing a given point every second is called the frequency.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=509&fit=crop&dpr=1 600w, https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=509&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=509&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=640&fit=crop&dpr=1 754w, https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=640&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/112479/original/image-20160223-16455-1h8xsog.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=640&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p>Every wave is a combination of interfering perfect waves, and so has a spectrum of different frequencies. Visible light waves, for example, have a spectrum of colours, with each colour corresponding to a different frequency.</p>
<p>They can actually be separated out into their spectrum by a prism, as Isaac Newton famously showed to develop his theory of colours. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/69610/original/image-20150121-29731-1ciiybx.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">A prism reveals the many colours of visible light.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/23629083@N03/14200678625">Flickr/final gather</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Different radio and television stations transmit their signals on waves made up of different frequency bands, so that we can tune into the frequency we want. </p>
<p>The distortions of perfect waves, at any given point in the medium, fluctuate up and down in strength either along the same direction the wave is moving (longitudinal waves), or at right angles (transverse waves). These choices depend on the medium, and are called polarisations.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=741&fit=crop&dpr=1 600w, https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=741&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=741&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=931&fit=crop&dpr=1 754w, https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=931&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/113173/original/image-20160229-27003-1gyu6cp.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=931&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Longitudinal and transverse waves.</span>
</figcaption>
</figure>
<p>Sound waves in air are longitudinally polarised, light and gravitational waves are transversely polarised, while the seismic waves causing earthquakes come in both varieties. As do <a href="https://www.youtube.com/watch?v=ilZj8JUTvy8">slinky waves</a>!</p>
<p>Perfect transverse waves have a further choice of the different directions at right angles to the direction the wave is moving in. Polaroid sunglasses take advantage of this, blocking the glare that comes from horizontal fluctuations, while letting through vertically polarised waves.</p>
<h2>Measuring waves</h2>
<p>Measuring waves is important in many parts of science, whether it gives us information about the source of the waves, or about the medium that they have travelled through.</p>
<p>For example, light waves emitted from the sun give us information about its temperature and composition, while light waves passing through a microscope slide can tell us whether someone needs medical treatment or not.</p>
<p>In all cases, the wave must be detected by some means, such as an eye or a camera. </p>
<p>Significant progress in science is made every time we learn how to generate or control or detect a new type of wave. Electromagnetic waves were only <a href="https://theconversation.com/let-there-be-light-celebrating-the-theory-of-electromagnetism-35723">discovered 150 years ago</a> and look at the use we make of them now, as mentioned before: radio, television and microwaves, to name just a few.</p>
<p>Gravitational wave detection is the most recent example, providing a unique window on those events strong enough to shake space and time themselves.</p>
<h2>A quantum twist</h2>
<p>At atomic scales and smaller, the distinction between waves and particles becomes somewhat blurred.</p>
<p>Sufficiently chilled-out atoms can start behaving as if they are spread out and <a href="https://www.learner.org/courses/physics/visual/visual.html?shortname=route_to_bec">overlapping each other</a>, rather like waves. And if the intensity of a light beam is dialled down enough, it is found to only illuminate <a href="https://www.youtube.com/watch?v=GzbKb59my3U">a single camera pixel at a time</a>, as if the beam was made up of particles.</p>
<p>Quantum mechanics tells us that waves and particles are fundamentally two sides of the same coin: different kinds of distortions in a medium. But the nature of the quantum medium is a profound mystery that drives the research of many scientists around the world (including my own).</p>
<p>It is only with its solution that we will finally understand just what waves are.</p><img src="https://counter.theconversation.com/content/54555/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Hall receives funding from the Australian Research Council and the Foundational Questions Institute.</span></em></p>We find them at the beach, in every sound and light show, the miracle of wi-fi and now in the fabric of space-time itself. But what exactly is a wave?Michael Hall, Senior Research Fellow, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/496462015-11-30T00:22:31Z2015-11-30T00:22:31ZEinstein’s folly: how the search for a unified theory stumped him to his dying day<figure><img src="https://images.theconversation.com/files/103578/original/image-20151130-11614-8zpwab.jpg?ixlib=rb-1.1.0&rect=0%2C304%2C4517%2C2934&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Albert Einstein wrestled with unifying gravity with electromagnetism and quantum mechanics until his dying days.</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/Category:Portraits_of_Albert_Einstein#/media/File:Albert_Einstein_1947.jpg">Oren Jack Turner/Wikimedia Commons</a></span></figcaption></figure><p>This month marks exactly <a href="https://theconversation.com/au/topics/general-relativity-centenary">100 years</a> since Albert Einstein submitted the first paper fully describing the <a href="https://theconversation.com/au/topics/general-relativity">general theory of relativity</a>. It was both breathtaking and revolutionary. </p>
<p>Simply stated, gravity is a geometric property of <a href="https://einstein.stanford.edu/SPACETIME/spacetime2.html#fourth_dimension">spacetime</a> that is allowed to be curved. It was like looking at Newton’s world through the bottom of a glass.</p>
<p>General relativity is based on Einstein’s field equations, which describe the relation between the geometry of a four-dimensional description of spacetime, and the <a href="https://theconversation.com/without-einstein-it-would-have-taken-decades-longer-to-understand-gravity-50517">energy–momentum</a> contained in that spacetime. </p>
<p>Spacetime curvature is caused by <a href="https://theconversation.com/explainer-what-is-mass-49299">mass</a>; the more mass, the more spacetime is curved. This curvature can induce deflections or delays in the propagation of light. </p>
<p>Even close to home, our sun – not that massive as stars go – will alter the path of light near it. Newton’s theory predicts a deflection of light of 0.875 <a href="http://astronomy.swin.edu.au/cosmos/A/Arcsecond">seconds of arc</a> at the limb of the sun, whilst relativity predicted a deflection of 1.75 seconds of arc. Observations during <a href="http://www.powerhousemuseum.com/collection/database/?irn=355470">total solar eclipses of background star fields</a> confirmed Einsteins value. </p>
<p>Even had Einstein died shortly after his work on general relativity, he would still be regarded by many today as the greatest physicist who ever lived, and perhaps even the greatest scientist. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102406/original/image-20151118-14222-1kp2toe.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&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 first part of Einsteins defining GTR paper: Feldgleichungen der Gravitation (The Field Equations of Gravitation) Preussische Akademie der Wissenschaften, Sitzungsberichte, 1915.</span>
</figcaption>
</figure>
<h2>Towards a unified field theory</h2>
<p>However, whilst he continued to work on many problems up until his death in 1955, he is regularly described as failing in one particular area: the <a href="http://www.britannica.com/science/unified-field-theory">unified field theory</a>. </p>
<p>From the 1920s, Einstein tried to develop a <a href="http://www.aps.org/publications/apsnews/200512/history.cfm">unified theory</a> that melded general relativity and <a href="https://theconversation.com/let-there-be-light-celebrating-the-theory-of-electromagnetism-35723">electromagnetism</a>, representing the only two forces known to exist.</p>
<p>Such a theory would describe a single field in which all forces are mediated and the properties of all particles – which at the time were only electrons and protons, with the <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/particles/neutrondis.html">neutron</a> not discovered until 1932 – could be deduced.</p>
<p>Other players in the quest appeared. <a href="http://www-history.mcs.st-andrews.ac.uk/Biographies/Kaluza.html">Theodor Kaluza</a> showed that if spacetime had five dimensions, then four dimensions could reflect general relativity, and one could represent electromagnetism. In the burgeoning <a href="http://www.pbs.org/transistor/science/info/quantum.html">quantum world</a> of the mid-1920s, <a href="http://www-history.mcs.st-andrews.ac.uk/Biographies/Klein_Oskar.html">Oskar Klein</a> shrank Kaluza’s 5th dimension to be compact, in a sense offering a quantum mechanical interpretation. </p>
<p>Einstein drew upon other work if it could help his cause. He even looked at variations to the successful mathematical basis of general relativity. It is <a href="http://www.stmarys.ac.uk/news/news/ug-applied-physics/2014/09/physics-beyond-god-play-dice-einstein-mean/">widely reported</a> that he did not support quantum mechanics, but promoted it (suffered it?) being a derivative of an eventual unified theory. </p>
<h2>Strong developments</h2>
<p>In a way, his mathematical focus hindered his acceptance of ongoing, major discoveries in physics like quantum mechanics. The discovery of two new forces in addition to gravity and electromagnetism – the <a href="http://www.livescience.com/48575-strong-force.html">strong</a> and <a href="http://www.thestargarden.co.uk/Weak.html">weak</a> nuclear forces – also made his work of a unified field based only on two forces unattainable.</p>
<p>Protons and neutrons in atomic nuclei had to be held together by a strong attractive force. Mesons, the force carrying particles for the <a href="http://aether.lbl.gov/elements/stellar/strong/strong.html">strong nuclear force</a> were discovered experimentally in 1947. Enrico Fermi in 1933 tried to explain beta decay, which was a radioactive transmutation between protons and neutrons. It was related to a <a href="http://home.fnal.gov/%7Echeung/rtes/RTESWeb/LQCD_site/pages/weakforce.htm">weak nuclear force</a>. </p>
<p>Eventually Sheldon Glashow, Steven Weinberg, and Abdus Salam announced a unified theory of electromagnetism and the weak nuclear force in 1968. Their <a href="https://www.fnal.gov/pub/inquiring/matter/madeof/electroweakforce.html">electroweak theory</a> postulated the weak force carrier particles – W and Z bosons – which were then discovered in the 1980s. </p>
<p>We now know that all forces <em>apart from gravitation</em> are related mathematically, albeit with some differences in phenomena. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=750&fit=crop&dpr=1 600w, https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=750&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=750&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=943&fit=crop&dpr=1 754w, https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=943&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/102418/original/image-20151118-14222-8yj7fq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=943&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 rich galaxy cluster Cl 0024+17. Blue streaks near the centre are smeared images of very distant background galaxies. Their light is being bent and magnified by the intervening cluster, in an effect called gravitational lensing.</span>
</figcaption>
</figure>
<h2>Todays efforts at a unified field</h2>
<p>The major pathway to unification over the last three decades has been <a href="https://theconversation.com/explainer-string-theory-2983">string theory</a>. Two forms of string theory have ten and twenty one dimensions respectively. In a strange parallel, the miniaturisation or compactification of many dimensions in string theory is the modern day equivalent of the <a href="http://www.superstringtheory.com/experm/exper5.html">quantisation of a 5th dimension</a> by Klein. </p>
<p>Despite little predictive power, and critics attacking its relation to a <a href="http://www.scientificamerican.com/article/multiverse-the-case-for-parallel-universe/">multiverse</a>, no other areas towards unification theory appear as fruitful as string theory.</p>
<p>For thirty years a unified theory proved a worthy opponent of Einstein. He worked on it even on his penultimate day in Princeton Hospital. <a href="https://www.ias.edu/people/oppenheimer">J. Robert Oppenheimer</a> was later both unflattering,</p>
<blockquote>
<p>During all the end of his life, Einstein did no good. He turned his back on experiments […] to realise the unity of knowledge. </p>
</blockquote>
<p>…and <a href="http://www.hup.harvard.edu/catalog.php?isbn=9780674034525">envious</a>,</p>
<blockquote>
<p>Of course, I would have liked to be the young Einstein. This goes without saying.</p>
</blockquote>
<p>A consensus seems to exist: in later years, Einstein worked with mathematical blinkers, immune to relevant discoveries, and unable to change his method of investigation. </p>
<p>As James Joyce <a href="http://www.online-literature.com/james_joyce/ulysses/">wrote</a>:</p>
<blockquote>
<p>A man of genius makes no mistakes. His errors are volitional and are the portals of discovery.</p>
</blockquote>
<p>Failure and mistake are harsh words. They are often the precursors of discovery. The unified field was Einstein’s nemesis for a variety of reasons. Despite this, many envied his early genius and we should focus on this especially in this centenary year of the greatest physics revolution.</p><img src="https://counter.theconversation.com/content/49646/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Glen Mackie 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>After the triumph of general relativity, Albert Einstein spent the rest of his life chasing a unified theory, which eluded him right up until the end.Glen Mackie, Senior Lecturer in Astronomy & Astrophysics, Coordinator of Swinburne Astronomy Online, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/512182015-11-26T16:35:55Z2015-11-26T16:35:55ZThe next war will be an information war, and we’re not ready for it<figure><img src="https://images.theconversation.com/files/103325/original/image-20151126-28284-146ghxe.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Interior_of_an_EC-130J_Commando_Solo_Mar_2003.jpg">Aaron Ansarov</a></span></figcaption></figure><p>In the 21st century the familiar form of warfare in which physical damage is meted out against the opponent’s military forces and infrastructure has become only one form of attack. Instead, states are increasingly launching non-lethal attacks against an enemy’s information systems – this is the rise of information warfare.</p>
<p>Dan Kuehl of the National Defence University <a href="https://books.google.co.uk/books?id=cBTYWOnmFbIC&pg=PR15&lpg=PR15&dq=%22conflict+or+struggle+between+two+or+more+groups+in+the+information+environment%22&source=bl&ots=6aAcUmPyX0&sig=-HCTZFx8DWhCIRNypFsx8Syv13s&hl=en&sa=X&ved=0ahUKEwioxeSa7avJAhWCeQ8KHfIRD4EQ6AEIIDAA#v=onepage&q=%22conflict%20or%20struggle%20between%20two%20or%20more%20groups%20in%20the%20information%20environment%22&f=false">defined information warfare</a> as the “conflict or struggle between two or more groups in the information environment”. You might say that just sounds like a fancier way of describing hacking. In fact it’s a lot more sinister and a lot more dangerous than its somewhat tame name implies. </p>
<p>Western leaders are investing billions to develop capabilities matching those of China and Russia, establishing military commands for attacking, defending and exploiting the vulnerabilities of electronic communications networks. Information warfare combines electronic warfare, cyberwarfare and <a href="http://www.iwar.org.uk/psyops/">psy-ops</a> (psychological operations) into a single fighting organisation, and this will be central to all warfare in the future.</p>
<h2>The anatomy of information warfare</h2>
<p>The free flow of information within and between nation states is essential to business, international relations and social cohesion, as much as information is essential to a military force’s ability to fight. Communications today lean heavily on the internet, or via communications using various parts of the electromagnetic spectrum (such as radio or microwaves) through terrestrial communications networks or satellite networks in space. We live in a highly connected world, but it doesn’t take much to tip over into instability or even chaos. </p>
<p>Electronic warfare is used to disrupt or neutralise these electromagnetic transmissions. These might be <a href="https://theconversation.com/how-syria-is-becoming-a-test-bed-for-high-tech-weapons-of-electronic-warfare-48779">electronic counter measures and jamming</a> used to cripple military communications or weapons guidance systems. Or it can include civil uses, for example the <a href="https://www.faa.gov/nextgen/programs/adsb">ADS-B</a> air traffic control system used by aircraft to avoid in-flight collisions, or the recently adopted European Rail Traffic Management System (<a href="http://www.ertms.net/">ERTMS</a>) that replaces railway trackside signalling and provides full control of trains. Jamming or degrading either of these would cause chaos.</p>
<p>We have become familiar with cyber-attacks launched through the internet against digital networks, which can make it impossible for businesses to operate. Enormous damage can follow, in cost and reputation, as seen from attacks on <a href="http://www.engadget.com/2014/12/10/sony-pictures-hack-the-whole-story/">Sony Pictures</a> and <a href="http://www.theweek.co.uk/66178/talktalk-hack-to-cost-35m-but-wont-dent-profits">TalkTalk</a>. Bringing down a stock exchange could cause massive financial losses. Cyber-attacks can also be directed at industrial control systems used in manufacturing plants or in power, water and gas utilities. With the capacity to affect such a wide range of national infrastructure lives would be put at risk.</p>
<p>Psy-ops are aimed more at degrading the morale and well-being of a nation’s citizens. This might include spreading false information, rumour and fear through social media and news outlets. The great level of connectedness that populations have today is a strength, but being instantly connected means that misinformation and fear can also spread rapidly, resulting in panic. </p>
<p>Information warfare, then, is the integration of electronic warfare, cyberwarfare and psychological operations, for both attack and defence.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/103326/original/image-20151126-28263-t0dsnc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&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 joined-up approach to the many aspects of information warfare.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/File:IO_Integration_into_Joint_Operations_-_Notional.jpg">US DoD</a></span>
</figcaption>
</figure>
<h2>Information war has already broken out</h2>
<p>It’s suspected that Russia has launched increasingly sophisticated non-lethal attacks on its neighbours, for example against <a href="http://www.economist.com/node/9163598">Estonia</a>, <a href="http://www.telegraph.co.uk/news/worldnews/europe/georgia/2539157/Georgia-Russia-conducting-cyber-war.html">Georgia</a> and <a href="http://foreignpolicy.com/2015/10/21/russia-winning-the-electronic-war/">Ukraine</a>, which experienced an integrated onslaught of electronic, cyber-attacks and psychological operations. </p>
<p>There is <a href="https://ics.sans.org/media/Media-report-of-the-BTC-pipeline-Cyber-Attack.pdf">convincing circumstantial evidence</a> that the Baku-Tbilisi-Ceyhan gas pipeline in Georgia was targeted using a sophisticated computer virus which caused an uncontrolled pressure build-up that led to an explosion. Even the so-called Islamic State has shown it has a good understanding of how to use and manipulate social media for use in psychological warfare. IS is reportedly building greater cyberwar and electronic warfare capabilities, as it recognises that winning the information war is key. </p>
<h2>A response to unconventional warfare</h2>
<p>In response to the threat of information war the British Army has established two new formations: the <a href="http://www.bbc.co.uk/news/uk-31070114">77th Brigade</a> for dealing with psychological operations, and the <a href="http://www.army.mod.uk/intelligence/35393.aspx">1st Intelligence, Surveillance and Reconnaissance Brigade</a> which combines electronic warfare and intelligence. Hundreds of computer experts will be recruited as reservists, trained with the help of GCHQ’s <a href="http://www.theguardian.com/uk-news/defence-and-security-blog/2013/sep/30/cyber-gchq-defence">Joint Cyber Unit</a>. </p>
<p>These are moves in the right direction, but the approach is too piecemeal. A recent <a href="https://www.rand.org/content/dam/rand/pubs/monograph_reports/MR1314/MR1314.ch6.pdf">RAND Corporation report</a> argued for a highly integrated approach to all aspects of information warfare in order to present an effective defence force. In the US, Admiral Michael S. Rogers released a <a href="http://www.defense.gov/News-Article-View/Article/616512/us-cyber-command-chief-details-plans-to-meet-cyberspace-threats">Cyber Command vision statement</a>, describing how it would defend Department of Defence networks, systems and information against cyber attacks and provide support to military and contingency operations. The US approach is more integrated but this is only the case within the military – from a national perspective both countries lack an overall integrated approach with a common command structure that includes threats to civilian infrastructure. </p>
<p>So while the concept of information war appears to be well understood the aspects of it are not being addressed together, and such siloed thinking could lead to gaps in our security. Western governments have failed to fully grasp the vulnerability of electronic communications and the enormous risks this poses to critical infrastructure, transport, and the safety of civilians.</p>
<p>The US director of intelligence has emphasised <a href="http://www.nationalsecurity.news/2015-09-14-u-s-intelligence-director-says-online-threats-growing-as-more-nations-dedicate-resources-to-cyber-warfare.html">the enormity of the cyber-threat facing the US</a>, while British General Sir Nicholas Houghton in a <a href="https://www.chathamhouse.org/event/building-british-military-fit-future-challenges-rather-past-conflicts">speech at Chatham House</a> observed that most acts of physical war today incorporate an online aspect, where social networks are exploited to manipulate opinion and perception. He also acknowledged that the tactics employed by Russia combine aspects of information war and also counter-intelligence, espionage, economic warfare and the sponsoring of proxies. </p>
<p>We need to better understand the full scope of information warfare as it evolves, identify where we are most vulnerable, and then establish a single point of responsibility to implement defence mechanisms. Because those adversaries that are unconstrained by western policies, or by ethical or legal codes, can and will exploit our vulnerabilities.</p><img src="https://counter.theconversation.com/content/51218/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Stupples 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>Warfare is changing, and our approach to dealing with our adversaries must change too.David Stupples, Professor of Electrical and Electronic Engineering and Director of Electronic Warfare Research, City, University of LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/506642015-11-19T04:24:48Z2015-11-19T04:24:48ZThe big data challenge and how Africa can benefit<figure><img src="https://images.theconversation.com/files/102326/original/image-20151118-14214-1vxrw3o.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Large Hadron Collider is playing a key role in enabling the collection of big data. </span> <span class="attribution"><span class="source">Supplied</span></span></figcaption></figure><p><a href="https://theconversation.com/explainer-what-is-big-data-13780">Big data</a> has become some sort of celebrity. Everybody talks about it, but it is not clear what it is. To unpack its relevance to society it is important to backtrack a bit to understand why and how it came to be this ubiquitous problem.</p>
<p>Big data is about processing large amounts of data. It is associated with multiplicities of data formats stored somewhere, say in a <a href="http://searchcloudcomputing.techtarget.com/definition/cloud-computing">cloud</a> or in distributed computing systems. </p>
<p>But the ability to generate data systematically outpaces the ability to store it. The amount of data is becoming so big and is produced so fast that it cannot be stored with current technologies in a cost effective way. What happens when big data becomes too big and too fast?</p>
<h2>How fundamental science contributes to society</h2>
<p>The big data problem is yet another example of how the methods and techniques developed by scientists to study nature have had an impact on society. The techno-economic fabric that underlies modern society would be unthinkable without these contributions.</p>
<p>There are numerous examples of how findings intended to probe nature ended up revolutionising life. Big data is intimately intertwined with fundamental science and continues to evolve with it.</p>
<p>Consider just a few examples: what would life be without electricity or electromagnetic waves? Without the fundamental studies of <a href="http://www.phy.pmf.unizg.hr/%7Edpaar/fizicari/xmaxwell.html">Maxwell</a>, <a href="http://www.nobelprize.org/nobel_prizes/physics/laureates/1925/hertz-bio.html">Hertz</a> and other physicists on the nature of <a href="http://www.merriam-webster.com/dictionary/electromagnetism">electromagnetism</a> we would not have radio, television or other forms of wave mediated communication, for that matter.</p>
<p>Modern electronics is based on materials called <a href="http://dictionary.reference.com/browse/semiconductor">semi-conductors</a>. What would life today be without <a href="http://www.thefreedictionary.com/electronics">electronics</a>? The invention of transistors and eventually of integrated circuits is based entirely on the work scientists have done by thoroughly studying semi-conductors.</p>
<p>Modern medicine relies on countless techniques and applications. These range from x-rays, medical imaging physics and nuclear magnetic resonance to other techniques such as radiation therapeutic and nuclear medicine physics. Modern medicine and research would be unthinkable without techniques that were initially conceived for scientific research purposes.</p>
<h2>How the information age came about</h2>
<p>The big data problem initially emerged as a result of the need for scientists to communicate and exchange data.</p>
<p>At the European laboratory <a href="http://home.cern/">CERN</a> in 1990, internet pioneer <a href="http://www.w3.org/People/Berners-Lee/">Tim Berners-Lee</a> suggested a browser called <a href="http://www.w3.org/People/Berners-Lee/WorldWideWeb.html">WorldWideWeb</a>, leading to the first web server. The internet was born. </p>
<p>The internet has magnified the ability to exchange information and learn, leading to a proliferation of data.</p>
<p>The problem isn’t only about volume. The time lapsing between the generation and processing of information has also been greatly reduced.</p>
<p>The <a href="http://home.cern/topics/large-hadron-collider">Large Hadron Collider</a> has pushed the boundaries of data collection to limits never seen before.</p>
<p>When the project, and its experiments, were being conceived in the late 1980s scientists realised that new concepts and techniques needed to be developed to deal with streams of data that were bigger than had ever been seen before. </p>
<p>It was then that concepts that contributed to cloud and distributed computing were developed.</p>
<p>One of the main tasks of the Large Hadron Collider is to observe and explore the <a href="http://home.cern/topics/higgs-boson">Higgs boson</a>, a particle connected with the generation of mass of fundamental particles, by means of colliding protons at high energy. </p>
<p>The probability of finding a Higgs boson in a high-energy proton-proton collision is extremely small. For this reason it is necessary to collide many protons many times every second. </p>
<p>The Large Hadron Collider produces data flows of the order of petabytes every second. To give an idea of how big a petabyte is, the entire written works of mankind from beginning of written history, in all languages, can be stored in about 50 petabytes. An experiment at the Large Hadron Collider generates that much data in less than one minute.</p>
<p>Only a small fraction of the data produced is stored. But even this has already reached the exabyte scale (one thousand times a petabyte) leading to new challenges in distributed and cloud computing.</p>
<p>The <a href="http://www.ska.ac.za/about/index.php">Square Kilometre Array</a> (SKA) in South Africa will start generating data in the 2020s. SKA will have the processing power of about 100 million PCs. The <a href="https://www.skatelescope.org/">data</a> it collects in a single day would take nearly two million years to play back on an iPod.</p>
<p>This will produce new challenges for the correlation of vast amounts of data.</p>
<h2>Big data and Africa</h2>
<p>The African continent often lags behind the rest of the world when it comes to embracing innovation. Nevertheless big data is increasingly being seen as a solution to tackling poverty on the continent.</p>
<p>The private sector has been the first to get out of the starting blocks.
The bigger African firms are, naturally, more likely to have big data projects. In Nigeria and <a href="http://www.africanbusinessreview.co.za/technology/1783/Big-Data-in-Africa:-IBM-Dissects-a-Developing-Trend-in-a-Developing-Market">Kenya</a> at least 40% of businesses are in the planning stages of a big data project compared with the global average of 51%. Only 24% of medium companies in the two countries are planning big data projects.</p>
<p>Rich rewards can be reaped from harnessing big data. For example, healthcare organisations can benefit from <a href="http://www.hissjournal.com/content/2/1/3">digitising</a>, combining and effectively using big data. This could enable a range of players, from single-physician offices and multi-provider groups to large hospital networks, to deliver better and more effective services. </p>
<p>Grasping the challenge of managing big data could have big economic spin-offs too. With economies becoming more and more sophisticated and complex the amount of data generated increases rapidly. As a result, in order to improve these complex processes it is necessary to process and understand increasing volumes of data. With this labour productivity is enhanced. </p>
<p>But for any of these benefits to become reality, Africa needs specialists who are proficient in big data techniques. Universities on the continent need to start teaching how big data can be used to find solutions to scientific problems. A sophisticated economy requires specialists who are skilled in big data techniques.</p><img src="https://counter.theconversation.com/content/50664/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bruce Mellado receives funding from the DST, NRF and the University of the Witwatersrand. </span></em></p>Big data is about processing large amounts of data. It is often associated with multiplicities of data. But the ability to generate data outpaces the ability to store it.Bruce Mellado, Professor of Physics, University of the WitwatersrandLicensed as Creative Commons – attribution, no derivatives.