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Arrow Of Time
Known as the "past hypothesis" problem, the Universe's initially low entropy has long puzzled scientists. Now, cosmic inflation solves it.
1hr 19mins
Theoretical physicist Jim Al-Khalili explores why our sense of time may be incredibly misleading, including the idea that past, present, and future might all exist at once.
3mins
The brain is an “illusion factory.” Here’s what that means for our perception of time.
Unlikely Collaborators
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.”
Whether you run the clock forward or backward, most of us expect the laws of physics to be the same. A 2012 experiment showed otherwise.
3mins
What drives the universe's expansion? Chemist Lee Cronin explains the theories linking time, space, and selection, providing a fresh perspective on this cosmic mystery.
Our thermodynamic arrow of time explains why the entropy of any isolated system always increases. But it can't explain what we perceive.
5mins
Why does time move forward but not backward? Physicist Sabine Hossenfelder explains.
7mins
How the Big Bang gave us time, explained by theoretical physicist.
1hr 33mins
Everything you ever wanted to know about the Universe, explained by physicist Sean Carroll.
You are trapped in time. You never live in the world as it is but only as you experience it as it was.
Ever since the start of the hot Big Bang, time ticks forward as the Universe expands. But could time ever run backward, instead?
We take for granted that time is real. But what if it's only an illusion, and a relative illusion at that? Does time even exist?
How efficiently could quantum engines operate?
Time always moves in the same direction, but what if the Universe were contracting? As we step forward in time, a number of things always seem to happen together. Objects […]
The combination of charge conjugation, parity, and time-reversal symmetry is known as CPT. And it must never be broken. Ever. The ultimate goal of physics is to accurately describe, as precisely […]
If you think you have problems today, be glad you’re not moving at the speed of light. Special relativity, even though it’s over 100 years old, is still one of the […]
In the far future, the last star burns out, stellar corpses get violently ejected, and galaxies accelerate away. And then the fun begins. For centuries, the biggest questions about our Universe […]