Theoretical Physics

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Theoretical Physics

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two particles different wavelength speed of light
Starts With A Bang
How to understand Einstein’s relativity without math
Times dilate and lengths contract near the speed of light. Bizarre and confusing? Sure. But under relativity, it can't be any other way.
Ethan Siegel
A dense cluster of differently sized red, blue, and green spheres overlaps against a black background, evoking the biggest mysteries surrounding the origin of the universe.
Starts With A Bang
We still don’t know how “hot” the hot Big Bang was
We've long known we can't go back to infinite temperatures and densities. But the hottest part of the hot Big Bang remains a cosmic mystery.
Ethan Siegel
Two identical, intricate, circular geometric patterns with symmetrical, multicolored lines and shapes are displayed side by side on a white background—each subtly reflecting the argument against theory of everything’s promise of perfect symmetry.
Starts With A Bang
The argument against the existence of a Theory of Everything
The Holy Grail of physics is a Theory of Everything: where a single equation describes the whole Universe. But maybe there simply isn't one?
Ethan Siegel
An older man in a suit and red tie sits on a chair against a white backdrop, with a colorful outer space scene in the background.
1hr 8mins
Full Interview
Michio Kaku wants to solve Einstein’s unfinished equation
“An equation, perhaps no more than one inch long, that would allow us to, quote, 'Read the mind of God.'”
Michio Kaku
bounce ball
Starts With A Bang
The Universe is not the same forward and backward in time
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.
Ethan Siegel
A visual simulation of two objects orbiting and merging, distorting a red-orange grid representing spacetime—illustrating gravitational waves once thought to be the worst prediction in science.
Starts With A Bang
Ask Ethan: Can we fix the worst prediction in all of science?
The measured value of the cosmological constant is 120 orders of magnitude smaller than what's predicted. How can this paradox be resolved?
Ethan Siegel
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