Gas turns into stars, which turns gas into energy and heavier elements.
Does this mean that the universe will run out of gas and stars in the distant future? Or is it a renewable process somehow?
Elements heavier than iron don't have exothermic fusion reactions. That and the universe is fundamentally on a one way street thanks to the second law of thermodynamics.
So a long long long time from now the universe will be dead in some sense.
>>7698447
Who knows... Who knows..
>>7698450
Man, I hope the ergodic hypothesis is false too.
>>7698455
Can you explain an ignorant what the hypothesis is about? Looked it up but the words are so long and confusing.
>>7698461
The ergodic hypothesis would imply that the universe cannot be corralled into any particular set of states. Because of that, the universe will eventually be spending almost all of its time wandering very numerous sets of boring states.
>>7698442
Black holes
>>7698442
Yes. The universe will eventually be mostly void of light.
>>7698442
INSUFFICIENT DATA FOR MEANINGFUL ANSWER.
>>7698442
Yes, in few hundreds of trillions of years the last red dwarf will die.
>>7698472
Isn't that just entropy?
>>7698653
>INSUFFICIENT DATA FOR MEANINGFUL ANSWER.
+1 for Asimov.
If you haven't read this short story you should.
http://multivax.com/last_question.html
>>7698447
It's interesting actually. The oft-described "heat death" of the universe assumes a total thermodynamic run-down of all matter but the final state hinges on a lot of assumptions and poorly or entirely undefined quantities, such as "the entropy of the universe" itself.
It seems that there is a lot of room there for inherent instabilities which, together with gravity, might rewind the universe from its death-throes.
Doesnt matter.
According to the cosmological constant states the as mass in the universe decreases, space between particles increases. Because of the laws of thermodynamics, the net mass of the universe is slowly shrinking.
In the extremely distant future, the space between whatever is left in the universe will be so distant, nothing will ever interract again. Cold, quiet death.
>>7698442
Our Universe is a long story about running out of gas.
First there was so much energy that particles and antiparticles formed and winked out of existence in moments.
The universe expanded, the energy density fell, and everything became a charged plasma.
The universe expanded, the energy density fell, and the plasma became atoms.
The universe expanded, the energy density fell, atoms dumped into giant mega hydrogen stars. These non-metallic stars had no metals and burned super-hot and super-fast. They ran out of fuel and exploded in Supernovae that make todays stars look puny.
Second generation stars formed from the ashes of the first generation stars. These burn and die. The big ones explode into supernovae, leaving black holes. The little ones collapse into tiny dull stars. Both processes seed additional heavier elements into the cosmos.
Time passes, the universe expands. Eventually there will not be enough hydrogen left to make one single star. When the last tiny star dies, the age of the star has ended. Black holes cool at infinitesimally slow rates due to Hawking Radiation. Long before the black hole completely cools, Tidal locking will rob away its angular momentum.
When the last black hole evaporates to nothing then the entire universe will be at a uniform temperature near absolute zero.
What happens next? We don't know. We think the universe is dead. It is practically nothing. If we look back at the history of the universe, it's probably not dead. Some new phenomena that is obscured by the temperatures and pressures of the modern universe will likely set off some new process.
We may never know. We, our species, our civilization, and every civilization we spawn will be long dead in the trillions of years before this happens.
>>7698697
when stars no longer exist, neither will the conversion of mass into energy (fissile materials will all have long since decayed by this point in time).
the mass of the universe will be constant
>>7698712
>what is radioactive decay
>>7698595
Right, you can create mini-black holes and throw iron in them, which produces more hawking-radiation.
>>7698714
There are two sentences in the post you replied to, and one of them specifically mentions radioactive decay. How did you even manage to miss that? Do you just start typing 0.5 seconds after you start reading?
>Let's see here, something about constant mass-- stop! No time to read the rest, gotta tell him he's wrong.
>>7698736
when the last star explodes, there will still be fissile material from the debris of that star. So you're still wrong.
>>7698712
Even protons decay. Its just takes a longer time than imaginable.
>>7698765
Protons have a half life of 10^32 years.
Even neutrinos will break up into photons over a similar length of time.
A universe of leptons is so low mass, the space between them will be too distant to interract with each other.
>>7698861
>protons have half life of 10^32 years
are we sure about this, i thought scientists werent sure, and depending on this, there are different issues for the universe, like every thing turning into iron 56 if the proton is stable
>pic very related
Microvac is going to solve this for us. Asimov said so.
http://multivax.com/last_question.html
>>7698712
That's not actually true; Hawking radiation allows the conversion of mass into energy via black hole decay.
>>7699154
>are we sure about this
No; most attempts to unify the strong nuclear force with other forces predict it, but attempts to observe proton decay have repeatedly failed, and those theories are not widely accepted. There was a big excitement about it in the eighties because we finally had a testable prediction, but then we tested it. 10^33 - 34ish years is simply the lower bound above which experiments haven't ruled it out yet.
>>7698450
Astrophysicists?
