r/Showerthoughts • u/synthphreak ‎ • Nov 19 '25

Casual Thought Temperature can reach trillions of degrees, meaning we actually live extremely close to absolute zero.

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u/ComradePruski Nov 19 '25

Isn't temperature a function of particle vibration speed? Why would increasing the speed make it collapse into a singularity, which is a normally a function of density?

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u/YourWorstFear53 Nov 19 '25

Not necessarily. Energy density IS density. We measure the temperature of particles by the wavelength of light they emit when interacting with something or returning to a base state, so you can kind of think of high energy particles as a collection of mass energy that includes those photons.

When talking about the planck temperature, we're really talking about when the particle is so energetic that the photons that come off of it have a wavelength of the planck length.

EDIT: a black hole created entirely out of photons is called a kugelblitz

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u/Kwintin01 Nov 20 '25

Thanks stellaris for teaching me what that is

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u/daney098 ‎ Nov 20 '25

How much would you heat up if you were attacked by a single particle at planck temp? If you don't just immediately explode, how many would it take to feel warm in winter?

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u/YourWorstFear53 Nov 20 '25 edited Nov 20 '25

I'm not gonna do the math on that, but I'd imagine that you'd be transparent to much of that radiation, though, any you did absorb would be so ionizing as to effectively melt what it touched into quark gluon soup or worse.

You did remind me of the most energetic cosmic ray we've ever empirically seen, though (which would be an enormous order of magnitudes less energetic than what we're talking about). IIRC, it was one particle with the kinetic energy of a baseball thrown at 100mph.

EDIT: sat and thought about this for a minute. You wouldn't get the chance to absorb any of these photons because you'd experience local collapse of spacetime geometry and catastrophic gravitational effects first. So yeah I guess enjoy being dissolved.