Question about Hawking Radiation and Iron Stars

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Discussion Overview

The discussion revolves around the concepts of Hawking radiation and the fate of ordinary matter, particularly in the context of iron stars and their potential evaporation. Participants explore the implications of black hole evaporation compared to the stability of non-black hole matter over extremely long timescales, touching on quantum tunneling and thermal radiation.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants propose that if protons are stable, ordinary matter will eventually turn into iron stars through quantum tunneling over an immense timescale, potentially on the order of 10^1500 years.
  • Others argue that ordinary matter should evaporate through Hawking radiation before reaching such a state, questioning the mechanisms behind this radiation.
  • It is noted that Hawking radiation is associated with event horizons, which iron stars do not possess, leading to the conclusion that they do not emit Hawking radiation.
  • One participant suggests that all matter radiates energy as a black body at a non-zero temperature, implying that ordinary matter must also lose mass over time, although the rate of energy loss is considered negligible compared to its mass.
  • Another participant challenges the idea that ordinary matter would evaporate similarly to black holes, emphasizing that the processes are not directly comparable.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between Hawking radiation and ordinary matter. There is no consensus on whether ordinary matter will eventually evaporate in a manner similar to black holes, and the discussion remains unresolved regarding the implications of thermal radiation for non-black hole objects.

Contextual Notes

Participants highlight the distinction between black holes and ordinary matter in terms of radiation and evaporation, but the discussion includes assumptions about the stability of protons and the nature of thermal radiation that are not fully explored.

Khursed
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TL;DR
Everything evaporates.
So, I was thinking, the most massive black holes are expected to evaporates in roughly a googol year. Fine.

But I was reading that if protons are stable, every planet and non black hole star remains are basically expected to turn into iron star from quantum tunneling after mind numbing time on the order 10^1500 years.

So my question is this, shouldn't they simply evaporate from Hawking's radiation first?
 
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Khursed said:
TL;DR Summary: Everything evaporates.

So, I was thinking, the most massive black holes are expected to evaporates in roughly a googol year. Fine.

But I was reading that if protons are stable, every planet and non black hole star remains are basically expected to turn into iron star from quantum tunneling after mind numbing time on the order 10^1500 years.

So my question is this, shouldn't they simply evaporate from Hawking's radiation first?
Why do you think they will emit Hawking radiation?
 
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Hawking radiation is due to an event horizon. Iron stars do not have am event horizon by themselves.
 
EmileJ said:
Hawking radiation is due to an event horizon. Iron stars do not have am event horizon by themselves.
That's right, so they don't emit Hawking radiation and therefore do not evaporate by emitting Hawking radiation. The same is true of everything else that is not a black hole: no Hawking radiation, therefore no evaporation no matter how long we wait.
 
Well, from what I understand, the principle behind Hawking's radiation is that everything radiates at the very absolute least as a black body of X temperature. Since nothing can ever reach absolute zero, it follows that you must emit something that invariably means you lose mass, as energy must come from somewhere.

Which is what made me conclude that if black holes eventually evaporates from Hawking's radiation after some googol years, I can't imagine how ordinary matter would fare any better.
EmileJ said:
Hawking radiation is due to an event horizon. Iron stars do not have am event horizon by themselves.
I get that. What I'm asking, is the way I understand it, Hawking figured out that black holes had to have at the very basic and most minimum level a temperature that was not zero, which means they are radiating thermally . Thus that radiation was called Hawking's radiation.

My own thought is this, if even black hole who are the most limited emitter of radiation evaporate within some googol years, then why wouldn't ordinary matter?

Unless my premise is wrong, and ordinary matter can settle to absolute zero frozen in time and emitting absolutely nothing? Otherwise, it must evaporate as well?
 
Khursed said:
from what I understand, the principle behind Hawking's radiation is that everything radiates at the very absolute least as a black body of X temperature
Where are you getting that from? Hawking radiation is specific to black holes.

It is true that the "iron stars" you describe in your OP will radiate energy as long as they have a temperature above absolute zero, and that means they will lose a little bit of mass as they radiate; but the amount of energy they will radiate, compared to their mass, is tiny. They will never even come anywhere close to evaporating away completely just because they radiate energy.
 
Khursed said:
ordinary matter can settle to absolute zero frozen in time and emitting absolutely nothing?
No. But ordinary matter can asymptotically approach absolute zero while emitting a total amount of energy that, compared to its mass, is tiny.

Khursed said:
Otherwise, it must evaporate as well?
Not at all. See above. The particular case of black holes evaporating away completely due to Hawking radiation is not just a general instance of "things radiate as long as they are above absolute zero".
 
PeterDonis said:
Where are you getting that from? Hawking radiation is specific to black holes.
Which is very fortunate since a new born baby would evaporate in a few femtoseconds while emitting a humongous amount of energy if it emitted Hawking radiation.
 
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