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General Relativity
Is the Universe finite or infinite? Does it go on forever or loop back on itself? Here's what would happen if you traveled forever.
The Universe is 13.8 billion years old, going back to the hot Big Bang. But was that truly the beginning, and is that truly its age?
The "first cause" problem may forever remain unsolved, as it doesn’t fit with the way we do science.
First derived by Emmy Noether, for every symmetry a theory possesses, there's an associated conserved quantity. Here's the profound link.
There are a wide variety of theoretical studies that call our Standard Model of cosmology into question. Here's what they really mean.
Physicists just can't leave an incomplete theory alone; they try to repair it. When nature is kind, it can lead to a major breakthrough.
Because of dark energy, distant objects speed away from us faster and faster as time goes on. How long before every galaxy is out of reach?
Symmetries aren't just about folding or rotating a piece of paper, but have a profound array of applications when it comes to physics.
The Multiverse fuels some of the 21st century's best fiction stories. But its supporting pillars are on extremely stable scientific footing.
To Fred Hoyle, the Big Bang was nothing more than a creationist myth. 75 years later, it's cemented as the beginning of our Universe.
When cosmic inflation came to an end, the hot Big Bang ensued as a result. If our cosmic vacuum state decays, could it all happen again?
So far, gravitational waves have revealed stellar mass black holes and neutron stars, plus a cosmic background. So much more is coming.
Although many of Einstein's papers revolutionized physics, there's one Einsteinian advance, generally, that towers over all the rest.
Without wormholes, warp drive, or some type of new matter, energy, or physics, everyone is limited by the speed of light. Or are they?
Want to avoid getting "spaghettified" by a black hole? Steer clear of the smaller ones.
Here's why the answer may forever elude scientists.
Physicists have yet to pinpoint the hypothetical matter that keeps galaxies from flying apart. Now they have a new focus.
Thanks to observations of gravitational waves, scientists were able to settle a longstanding debate over the speed of gravity.
For generations, physicists have been searching for a quantum theory of gravity. But what if gravity isn't actually quantum at all?
The brilliant mind who discovered the spacetime solution for rotating black holes claims singularities don't physically exist. Is he right?
Our intuitive understanding of time is very different from a physicist's understanding of time. How do we reconcile these views?
Roger Babson wanted a “partial insulator, reflector, or absorber of gravity” — something, anything, that would stop or dampen it.
All matter particles can act as waves, and massless light waves show particle-like behavior. Can gravitational waves also be particle-like?
If the Universe is expanding, and the expansion is accelerating, what does that tell us about the cause of the expanding Universe?
Everything we observe beyond our Local Group is speeding away from us, omnidirectionally. If the Universe is expanding, where is the center?
12mins
When black holes disappear, what happens to the stuff that fell in? Physicist Brian Cox explains.
If you said "with the Big Bang," congratulations: that was our best answer as of ~1979. Here's what we've learned in all the time since.
Einstein's theory of general relativity introduced the concept of space having a shape. So, what is the shape of space?
There's a quantum limit to how precisely anything can be measured. By squeezing light, LIGO has now surpassed all previous limitations.
From the Big Bang to black holes, singularities are hard to avoid. The math definitely predicts them, but are they truly, physically real?