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[Sergarr]

Well the black holes must evaporate anyway, because the earth isn't yet consumed by the micro-black-holes which are created from ultra-relativistic particles impacts...

But passing the horizon in finite time breaks too many conservation laws.....

[iceball3]

Well the black holes must evaporate anyway, because the earth isn't yet consumed by the micro-black-holes which are created from ultra-relativistic particles impacts...

Again, I'm talking sort of hear-say on this, but aren't there black holes that are small enough just be considered Weakly Interacting Massive Particles, due to the fact that it can spit out hawking radiation due to not being able to impart more than the minimal increment of energy possible, yet by the same token not being strong enough to take in anything as big as the minimum increment (which does not split, so simply doesn't happen)?
I can't remember where i heard the full explanation of this, so i might just being putting out nonsense, but eh

[GavJ]

^
I think he was simply suggesting that since the tiny ones evaporate, the large ones eventually must as well, since they spit out radiation, and since at some point, they must stop bringing in matter (because eventually they'll clear the entire reachable locality, or move to the edge of space, or whatever). Therefore, the "smallifying" side of the process will win at some point.

If so, then at least for purposes of that argument, the terminology of what you call small black holes isn't that important.

[iceball3]

^
I think he was simply suggesting that since the tiny ones evaporate, the large ones eventually must as well, since they spit out radiation, and since at some point, they must stop bringing in matter (because eventually they'll clear the entire reachable locality, or move to the edge of space, or whatever). Therefore, the "smallifying" side of the process will win at some point.

If so, then at least for purposes of that argument, the terminology of what you call small black holes isn't that important.

Actually, i'm thinking that heat-death of universe nonwithstanding, persistent background radiation and other environmental factors will typically be adding more mass to black holes than much larger ones release, i think. I think the scaling of the hawking radiation released slows down as black holes get bigger.

[GavJ]

Right, but background radiation will eventually stop. Every radiation source has a halflife (if it doesn't, then it is not actually radioactive...).
Maybe that's what you meant by "heat death notwithstanding" if so then simply yes -- I am taking into account heat death as part of it. Don't see why it shouldn't be withstanding (is that how you'd say that? =P)

[Descan]

Except probably hydrogen :v

Also, microwave background radiation is the residual heat/radiation from the big bang... I guess eventually it'll settle down to near absolute zero (it's within a few degrees right now)

[Putnam]

Except probably hydrogen :v

Nah, greatorder's talking about the possibility of proton decay, I think.

[GavJ]

Except probably hydrogen :v

Also, microwave background radiation is the residual heat/radiation from the big bang... I guess eventually it'll settle down to near absolute zero (it's within a few degrees right now)

You can't destroy energy, but it can and will spread out thinner and thinner, until eventually every little photon is flying off in some trajectory that has a 0% chance of ever intercepting a black hole.

[Descan]

Aye, I said settle down, not "go away."

Or do you mean for children to be annihilated in a fireball of death when you tell them to "Settle down now!"?

[GavJ]

Or do you mean for children to be annihilated in a fireball of death when you tell them to "Settle down now!"?

We're on a dwarf fortress forum. I think the answer to that question should be obvious 

[alway]

Except probably hydrogen :v

Also, microwave background radiation is the residual heat/radiation from the big bang... I guess eventually it'll settle down to near absolute zero (it's within a few degrees right now)

You can't destroy energy, but it can and will spread out thinner and thinner, until eventually every little photon is flying off in some trajectory that has a 0% chance of ever intercepting a black hole.

As has been said before, black holes evaporate (larger evaporate much more slowly though; so their evaporation comes more in the form of sparks of radiation as the wink out of existence, with nary a trickle until then). In about 10^14 years, star formation stops (and with it, the formation of any considerably sized black holes). In around 10^100, black holes are expected to all evaporate. So that's the boring stuff of our current universe.

Depending on the end result of macro-scale physics, weird things may happen after this.

There's the "Big Rip" idea, in which expansion accelerates and makes macro-scale physics meaningless; though I've not actually heard much support for this. Big Crunch theories were fairly standard originally; of course, then we discovered the expansion was accelerating. So there's that general category of 'ends' to time.

Then there's the alternative, in which over strange eons, even the death of the universe may die.
https://en.wikipedia.org/wiki/Poincar%C3%A9_recurrence_theorem
Essentially, infinite time overrides chaos and entropy. These are both based on statistical rules; and when you introduce infinities to statistics, you end up with a result in which all possibilities eventually happen, albeit with unimaginably vast eras of boredom in between. Even the evaporation of black holes is beyond the time scales we can possibly fathom; but is only a tiny blip in time compared to these. After all, it is literally the amount of time it takes for random photons and fluctuations at the quantum level to spontaneously start off a low-entropy event similar to the big bang. Ridiculously vast, beyond comprehension or imagination. Beyond Lovecraftian. So yeah. Over infinite eons, statistics dictates that even the death of the universe will die (assuming no event first occurs to rip apart time itself).

That, of course, is speculating based on known physics. So far as we know, it may well be turtles all the way down, and there may well be a larger, timeless multiverse (linear time being a property of this universe, and tied up with its space, we don't really have a reason to think it would exist/be the same outside of the universe).

[GavJ]

Unless we actually KNOW that big bangs can happen from random photon fluctuations or whatever (do we?), statistics does not actually dictate that.

Infinite time only leads to an assured event if you KNOW that the event has a greater than 0% chance of happening per unit time going forward.

If all you know is that there's a % chance that the % chance per time is not zero, then you can't make such claims. As far as I am aware, we do not know that the chance per time is > 0%, and thus there is a possibility that literally nothing "interesting" can ever happen in all the expenses of infinite time, beyond a certain point.




In other words, we can probably have no way of ever proving that nothing interesting will happen (it always might be the case that external-to-our-universe forces will perturb the system that we would have no way to observe ahead of time), but that doesn't equate to "they will." Because there might simply not be any such forces, or any method by which a photon can cause a big bang, or whatever.


In the wiki page you cited, (one of) the critical assumptive flaws here for applying to the universe is laid out pretty explicitly:

For a mechanical system, this bound can be provided by requiring that the system is contained in a bounded physical region of space

[Putnam]

The chance that the chance is more than 0% is significantly higher than the chance is 0%, especially since we don't know the chance itself.

[GavJ]

Even the chance of the chance would probably have to be based on the intuitions of highly trained physicists, etc. I for one, and probably any other lay person here, wouldn't have anything to go on at all to even guesstimate that. It might be the case that even entertaining a notion of such things happening is fairly absurd amongst those in the know. Or they might all have a hunch that it's very likely.

[Il Palazzo]

You can't destroy energy, but it can and will spread out thinner and thinner, until eventually every little photon is flying off in some trajectory that has a 0% chance of ever intercepting a black hole.

Yes you can. CMB photons, and any photons travelling through expanding space are continually being redshifted = losing energy. It's not a matter of energy density going down, but energy of individual photons dissipating.

Conservation of energy is a concept that is undefined on cosmological scales. Here's a good article about it: http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html