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Spacetime Physics
We have two descriptions of the Universe that work perfectly well: general relativity and quantum physics. Too bad they don't work together.
Binary black holes eventually inspiral and merge. That's why the OJ 287 system is destined for the most energetic event in history.
No human has ever left the Solar System, and only six already-launched spacecraft will ever exit it. Will Voyager 1 remain the most distant?
Quantum entanglement links information between particles across space and time. So what happens when one of them falls into a black hole?
3mins
The brain is an “illusion factory.” Here’s what that means for our perception of time.
Unlikely Collaborators
16mins
“The messy reality of it is that all of these very smart people, including Isaac Newton, were talking to other people.”
1hr 26mins
“I like to say that physics is hard because physics is easy, by which I mean we actually think about physics as students.”
Many of us look at black holes as cosmic vacuum cleaners: sucking in everything in their vicinity. But it turns out they don't suck at all.
Humans, when we consider space travel, recognize the need for gravity. Without our planet, is artificial or antigravity even possible?
Time is relative, not absolute, as gravity and motion both cause time to dilate. Your head and feet, therefore, don't age at the same rate.
The mass that gravitates and the mass that resists motion are, somehow, the same mass. But even Einstein didn't know why this is so.
Traveling back in time is a staple of science fiction movies. But according to Einstein, it's a physical possibility that's truly allowed.
The evidence that the Universe is expanding is overwhelming. But how? By stretching the existing space, or by creating new space itself?
The brilliant mind who discovered the spacetime solution for rotating black holes claims singularities don't physically exist. Is he right?
Isaac Newton and Albert Einstein are locked in an eternal battle over the nature of gravity. Whose side are you on?
Measurements of the acceleration of the universe don’t agree, stumping physicists working to understand the cosmic past and future. A new proposal seeks to better align these estimates — and is likely testable.
12mins
Quantum wormholes are mathematically possible — but might also be physically impossible. Physicist Janna Levin explains Hawking’s famous information paradox.
The first observational evidence showing the Universe is expanding is 100 years old now: in 2023. Here's the story of its 100th anniversary.
Ultracold gases in the lab could help scientists better understand the universe.
Invisible cloaks. Ghost imaging. Scientists are manipulating light in ways that were once only science fiction.
From a photon's viewpoint, the Universe is timeless and dimensionless.
There are 40 billion billion black holes in the universe. Here’s how our Solar System stacks up against ten of them.
It's been 100 years since we discovered that the Universe was expanding. But if it's expanding, then what is it expanding into?
Einstein's most famous equation is E = mc², which describes the rest mass energy inherent to particles. But motion matters for energy, too.
Einstein's relativity overthrew the notion of absolute space and time, replacing them with a spacetime fabric. But is spacetime truly real?
9mins
Sabine Hossenfelder discusses the physics of… dead grandmothers?
Time gets a little strange as you approach the speed of light.
Everything everywhere all at once.
3mins
Left–Right, Back–Forth, Up–Down. What’s the fourth dimension?
There's the textbook answer, then there's the real answer.