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General Relativity
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?
In the quest to measure how antimatter falls, the possibility that it fell "up" provided hope for warp drive. Here's how it all fell apart.
Sci-fi enthusiasts have long hoped that a substance called antimatter might experience gravity opposite that of ordinary matter. It doesn't.
5mins
NASA’s Michelle Thaller explains what happens when the densest stars in the galaxy collide.
A more distant galaxy liked the lens so much that it went and put a ring on it. Here's the science behind this remarkable cosmic object.
This measurement is crucial to confirm that one of the assumptions of Einstein’s theory of gravity is valid.
Dark matter hasn't been directly detected, but some form of invisible matter is clearly gravitating. Could the graviton hold the answer?
The matter that creates black holes won't be what comes out when they evaporate. Will the black hole information paradox ever be solved?
When it comes to predicting the energy of empty space, the two leading theories disagree by a factor of 100 googol quintillion.
Newton thought that gravitation would happen instantly, propagating at infinite speeds. Einstein showed otherwise; gravity isn't instant.
When the average person has a "theory," they're just guessing. But for a scientist, a theory is the pinnacle of what we can achieve.
5mins
Gravity defies quantum mechanics. What does that mean for a theory of everything?
The Universe isn't just expanding, the expansion is also accelerating. If that's true, how will the Milky Way and Andromeda eventually merge?
By probing the Universe on atomic scales and smaller, we can reveal the entirety of the Standard Model, and with it, the quantum Universe.
The first observational evidence showing the Universe is expanding is 100 years old now: in 2023. Here's the story of its 100th anniversary.
Some constants, like the speed of light, exist with no underlying explanation. How many "fundamental constants" does our Universe require?
Two fundamentally different ways of measuring the expanding Universe disagree. What's the root cause of this Hubble tension?
How scientists are hearing the gravitational background "hum" of the Universe for the very first time.
Nothing can escape from a black hole. So where do Hawking radiation, relativistic jets, and X-ray emissions around black holes come from?
The concept of the warp drive is currently at odds with everything we know to be true about physics.
For many years, cosmologists have claimed the Universe is 13.8 billion years old. A new paper says no, it's 26.7 billion. How do we decide?
Some 55 million light-years away lies the giant galaxy Messier 87. Its supermassive black hole, inside and out, looks better than ever.
Headlines have blared that quasar ticking confirms that time passed more slowly in the early Universe. That's not how any of this works.
After 15 years of monitoring 68 objects known as millisecond pulsars, we've found the Universe's background gravitational wave signal!