Understanding how energy disappears

[esvion]

I've been reading about the possible ends to the universe and I came across the "big freeze".

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

In this scenario, all the energy in the Universe goes out and the Universe is cold and desolate with no stars. But the law of conservation of energy states that energy cannot be destroyed. Where did all this energy go then?

It's like when I punch something imaginary in mid air. What happens to the energy momentum in my fist after I am done punching? Does it vibrate the air molecules around me on such a small level into infinity?

I see energy disappear around me all the time, such as when a light bulb runs out. What happens to the photons that the light bulb was giving off the entire time before it burnt out?

Any help would be appreciated. Thanks!

Edit:
How can electrons go through houses and what not. I was wondering about radio waves and how they're just electrons moving out of the broadcasting location. Do these electrons also continue forever into space? And how do they have enough energy to go on forever?? More importantly, can these radio wave electrons get bonded to something in some sort of electric-chemical reaction?

[ZapperZ]

Edit:
How can electrons go through houses and what not. I was wondering about radio waves and how they're just electrons moving out of the broadcasting location. Do these electrons also continue forever into space? And how do they have enough energy to go on forever?? More importantly, can these radio wave electrons get bonded to something in some sort of electric-chemical reaction?

Radio waves are not electrons. They are electromagnetic waves, just like visible light, only with longer wavelengths and can be "diffracted" rather easily through openings like doors and windows.

Next time, you should not ask two very different questions in a single post/thread. It makes it confusing when people start responding to it.

Zz.

[russ_watters]

I've been reading about the possible ends to the universe and I came across the "big freeze".

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

In this scenario, all the energy in the Universe goes out and the Universe is cold and desolate with no stars. But the law of conservation of energy states that energy cannot be destroyed. Where did all this energy go then? You are right - the energy of the universe has to be constant. In a "Big Freeze" scenario, as it says in the Wik link, the low temperature is due to the size of the univers: as the universe expands, the energy spreads out into more and more space, eventually becoming so diluted that the energy density is very low.

This, btw, is the reason that the cosmological micrwoave background radiation is so low of an energy (2.4 K iirc) despite being an 'image' of moments after the big bang. It's like when I punch something imaginary in mid air. What happens to the energy momentum in my fist after I am done punching? Does it vibrate the air molecules around me on such a small level into infinity?

I see energy disappear around me all the time, such as when a light bulb runs out. What happens to the photons that the light bulb was giving off the entire time before it burnt out? Most forms of energy are eventually dissipated as heat. A light bulb emits light, which is absorbed by your walls and floor and heats them.

When you punch the air, the energy is absorbed by your shoulder and muscles. That's why it hurts!

[Unkraut]

I've been reading about the possible ends to the universe and I came across the "big freeze".

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

In this scenario, all the energy in the Universe goes out and the Universe is cold and desolate with no stars. But the law of conservation of energy states that energy cannot be destroyed. Where did all this energy go then?

The energy does not vanish. It is just spread out more or less uniformly throughout an ever-growing universe. At the end of this scenario the whole universe will have the same temperature (slightly above 0 Kelvin), almost all matter will have collapsed to black holes which are so far apart (and still drifting away) from each other that there is almost no gravitational force left between them. The energy has just developed to a state where it cannot be transferred anymore because it is in thermal equilibrium.
But this scenario can only take place if the total mass in the universe is less than some critical value. If there is enough mass the universe will collapse due to its gravitation.


It's like when I punch something imaginary in mid air. What happens to the energy momentum in my fist after I am done punching? Does it vibrate the air molecules around me on such a small level into infinity?

Yes. The kinetic energy of your fist will transform mostly into molecular chaotic movement = heat energy. Everything eventually ends up as heat

I see energy disappear around me all the time, such as when a light bulb runs out. What happens to the photons that the light bulb was giving off the entire time before it burnt out?

The photons are absorbed somewhere and transform their energy to heat eventually.


How can electrons go through houses and what not. I was wondering about radio waves and how they're just electrons moving out of the broadcasting location. Do these electrons also continue forever into space? And how do they have enough energy to go on forever?? More importantly, can these radio wave electrons get bonded to something in some sort of electric-chemical reaction?

Radio waves are electromagnetic waves - just the same as light. Electromagnetic waves do not consist of electrons but of photons.