What happens when all the energy is used up?

[spurius]

They say stars form from the material ejected from bigger exploding stars, or from clumps of material already out there like M42. Well theres only so much times that stars can do this. Is there some form of energy/matter recycling or even replenishment going on? What happens when all this energy runs out?

[gkec]

This probably

http://en.wikipedia.org/wiki/Heat_death_of_the_universe

[ronin]

The universe ends.

Not due to occur yet, sometime after the bank holiday.

[mallorcasaint]

The law of conservation od energy states that energy cannot be created or destroyed in a closed system? Energy can change form, from kinetic to thermal for instance but is never destroyed.

[JB80]

They say stars form from the material ejected from bigger exploding stars, or from clumps of material already out there like M42. Well theres only so much times that stars can do this. Is there some form of energy/matter recycling or even replenishment going on? What happens when all this energy runs out?

Isn't that the second law of thermodynamics?

Entropy and all that?

http://en.wikipedia.org/wiki/Second_law_of_thermodynamics

[Tiki]

Perhaps The Big Cold.

... What happens when all this energy runs out?

The Big Cold perhaps.

[MartinB]

The answer to you question is, absolutely nothing!

[Knight of Clear Skies]

The average rate of star formation is slowing; by one estimate, 95% of all the stars that will ever form already have. Eventually, all star formation will stop and existing stars will die. White dwarfs will cool to become black dwarfs, leaving the universe a cold, dark place.

Beyond that, it's not possible to say what will happen, although there are a number of theories. If the expansion of the universe continues, here is a possible timeline.

[acey]

Energy is conserved (first law of thermodynamics) but entropy cannot decrease (second law), so over time the energy gets shared out more and more evenly, until you arrive at a state in which everywhere is at the same (very low) temperature. To do it properly you also need to factor in gravity (black holes and their evaporation) and the cosmological constant (dark energy) but the end result is the same - a universe that is very cold and empty.

[ollypenrice]

The energy, we must remember, becomes ever more thinly distributed in an expanding universe. The more it expands the colder it gets.

Great answer from Martin, earlier!

Olly

[Peter Drew]

I go to bed!

[Naemeth]

+1 for Acey and Mallorcaisant. Energy can't be destroyed, but will all eventually move to the least efficient form, heat. It will take a long time to get to that though (if the Universe doesn't start contracting and then form another one).

http://en.wikipedia....of_the_universe

P.S. +1 for gkec too, I didn't notice the link earlier which is the same as this

[stellarpunk]

Achy has it

Law 1 there's no such thing as a free lunch

law 2 you can't win!

But all heat is really is a measure of the kinetic energy of matter... Particles either move, or they don't

[AlexB67]

Peter Drew is bang on the money, the simplest answers form the most elegant theories are often the best, I like it

[endure]

You'll have to start brewing your own beer

[101nut]

Achy has it

Law 1 there's no such thing as a free lunch

law 2 you can't win!

But all heat is really is a measure of the kinetic energy of matter... Particles either move, or they don't

As an addition to this, the matter itself will eventually decay into photons which will in turn lose their energy as they inexorably increase wavelength with universe expansion. Kinetic energy will no longer exist when matter ceases to exist (unless photons do have rest mass) and everything will become vacuum energy (whatever that is) at the ground state. At this point, arguably, the normal spatial dimensions and even time itself may cease to exist.

The problem here is that there is still the same, huge amount of energy in the universe as there is today, but there's no matter. So although the answer 'nothing' above is a good, accurate statement of fact when referring to matter but it is not exactly true as there's lots of "photons" of vacuum-energy at the ground state in the nothing ... so obviously there's a lot of nothing-stuff in the nothing!

Now, using quantum theory, it's always possible that all the no low-energy photons will suddenly disappear and reappear in one "place", or in fact this "place" could just be a simple resonant node of all the vacuum-photons in the universe at a wavelength equal to twice (?) the "size" of the universe ... the energy density at the nodal position would be massive and may result in some kind of large energy explosion (let's call it a "big bang") ... hmm ... 'nothing' has just formed 'everything' ... here we go again

AndyG

[ollypenrice]

I've done a lot of concrete this week - observatory bases etc, over five tonnes - and at sixty I have to say that the thread feels threateningly personal! Martin's answer retains the critical ring of truth...

Olly

[Northern Soul man]

SORRY - guys and gals your missing the point - when all the energy runs out I get

the Mrs to carry the mount out,

level the mount

carry the scope out,

mount the scope

carry the power tank out

carry the star diag out

mount the star diag

carry the finder out

mount the finder

carry the handset holder out

mount the handset holder

carry the ep box out

open the ep box

mount the ep

switch on

You get the picture

I was going to say then I mount the ### but forgot haven't got the energy to.!!!!!!

Paul