Our two best theories of nature, quantum mechanics and general relativity, are incompatible with each other in many ways – leaving physicists to dig deeper.
Time gets a little strange as you approach the speed of light.
ikonacolor/iStock via Getty Images
Cutting-edge theories of physics suggest time may not be real – but even if they’re right, life can still go on as usual.
Experiments at the Large Hadron Collider in Europe, like the ATLAS calorimeter seen here, are providing more accurate measurements of fundamental particles.
Maximilien Brice
Physicists know a lot about the most fundamental properties of the universe, but they certainly don’t know everything. 2021 was a big year for physics – what was learned and what’s coming next?
An artist’s impression of the Double Pulsar system in which the two pulsars orbit each other every 2.5 hours and send out high-energy beams that sweep across the sky.
Image credit: John Rowe Animations/CSIRO
Such a mission could be developed soon, allowing astrophysicists to take selfies of the solar system and use the Sun’s gravity as a lens to peer deep into space.
Gravity feels like it’s pulling everything toward Earth, but why?
AdventurePhoto/E+ via WikimediaCommons
Gravity is something every person on Earth intuitively understands: It is what keeps you on the ground. But how come gravity pulls down, rather than pushes up? Einstein came up with the answer.
If humanity wants to travel between stars, people are going to need to travel faster than light. New research suggests that it might be possible to build warp drives and beat the galactic speed limit.
Field theory describes the universe as energy flowing along unending lines. With this perspective, it is possible to define a new fundamental building block of matter.
Roger Penrose helped resurrect Einstein’s general theory of relativity, and Reinhard Genzel and Andrea Ghez showed there was a black hole in the middle of our galaxy.
This image of the NGC 1398 galaxy, which is located in the Fornax cluster, was taken with the Dark Energy Camera.
Dark Energy Survey/Flickr
The crucial phase of our discovery of black holes took place in a suitably dark period of human history – World War II.
An artist’s impression of the path of star S2 as it passes very close to the supermassive black hole at the centre of the Milky Way. The very strong gravitational field causes the colour of the star to shift slightly to the red. (Size and colour exaggerated for clarity.)
ESO/M. Kornmesser
Astronomers traced a single star as it passed close to the black hole at the centre of our galaxy, and detected the telltale signature of Einstein’s gravity in action.