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mschurma t1_iuf85ez wrote

Reply to comment by BlueTommyD in When the last star dies by trunktunk

Layman question and it’s been awhile since physics class lol, what happens to the mass let off by all the Hawking radiation at that point? Is there any mechanism that converts radiation back to mass? I get E=mc2, that energy would still exist right? Is there any mechanism that could start turning that back into matter, and given time/gravity, start forming stars again?

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3Dbpb t1_iugetpw wrote

Not a theoretical physicist but I believe the theorized mechanism involves virtual particles. They are pairs of particles that pop up everywhere in particle antiparticle pairs. Normally they recombine nearly instantly but at the event horizon it may be that one of the paired particles falls into the black hole and the other escapes.

The issue with reforming stars is the universe is expanding at an accelerating rate. Which means while there will still be particles they will be isolated and too far away to combine into stars.

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carbonqubit t1_iuggct6 wrote

Virtual particles are a bit of a misnomer, as they're actually mathematical constructs that arise from perturbation theory and used to resolve certain complexities in quantum mechanics. Said another way, theoreticians use them to help better estimate particle interactions like those between say two electrons.

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BlueTommyD t1_iufbhhb wrote

Right. There is no ELI5 for Hawking Radiation - it's too weird. And I am not a Quantum Physicist.

Hawking Radiation is a particular kind of Thermal Radiation that "leaks" from the tiny distance around the Event Horizon of a Black Hole. The radiation never actuallty comes from "inside" the Event Horison, yet it steals energy from the Black Hole - and in a Black Hole, mass and energy are essentially the same thing.

Hawking Radiation itself isn't perfect - and could to the Black Hole Information Paradox - where Black Holes *are* actually deleting information from the universe - although this is up for debate and there are theories which correct for this.

As far as I am aware, you can't turn the energy emitted back in to mass - without just throwing it in to another black hole.

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Other_Evidence8818 t1_iuglcnz wrote

Fusion and fission are mechanisms for turning energy into matter. But after heat death, on average these processes won't be occurring as there are no gradients.

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