Energy where does it come from?!

Farahday

Energy is a condition. Mass is a condition. They are interchangeable according to Uncle Al. Fathom, for a moment, that there are things other than mass and energy. In fact most of the cosmos is comprised of such things.

BTW - I always try to keep my ying-yang balanced

Drakkith

What do you mean by saying the cosmos is comprised of stuff other than mass and energy?

Mark M

Sorry for not noticing this reply earlier Drakkith, I'll reply now:

Right, nothing wrong with the coffee, it's just a statistical fluctuation. Now, for the other two: let's consider the rock.

So, when you drop a rock from some height, it starts with some potential energy. When it is released, the potential energy converts to kinetic energy very rapidly, until the potential energy is zero and kinetic energy is maximum (moment of impact). Now, the rock's potential energy is zero, and so is the kinetic energy, since it's just sitting on the ground. What happened to the energy? Well, some, because of Newton's third law, is transferred to the earth. So, the earth moves an absolutely minuscule amount. Much of the rest of the energy becomes heat energy, useless energy (in the sense that it can't do work, since it has very high entropy).

If the second law didn't exist, this could happen backwards. The earth could transfer some movement to the rock, and the heat energy could be re-absorbed. This becomes kinetic energy, causing the rock to move up until gravity is too strong to continue, at which point the rock is in the original position.

So, why don't we see this happening? Well, because of the second law, the heat is absolutely useless since it has a very high entropy. It can't do anything. However, since we know the second law is a statistical law, this could happen.

Similarly, with the chemical reaction, the higher entropy result normally doesn't become the chemicals that went into the reaction because this would constitute a decrease in entropy. But, they could come to together in just the right way to do the reaction in reverse (and gaining any energy released via heat). But don't bet on seeing it happen.

Drakkith

I think I see what you are saying Mark. Consider my examples to mean that all this happens for NO reason. IE the rock is moved back up to it's starting position and the heat it created still exists, while the CO2 splits and combines back into gasoline yet there isn't enough energy to do so to all the molecules.

bluey

Where did you get the idea that I was talking philosophy and that everyone else here is talking cosmology? We are talking about Energy and where it comes from if I'm not mistaken? By the way, do you have any constructive take on the question at hand?

Mark M

Well, the heat energy that the rock lost during the collision was regained and became kinetic energy, which gave it the ability to move upward, until gravity converted all of the kinetic energy back into potential energy. So, we could think of it like this:

total energy of system when rock is on ground = momentum the earth received from the collision + heat energy

total energy while rock is moving upward = kinetic energy + potential energy

total energy while rock is at maximum height = potential energy

We could then separate the total system into two parts - the rock, and the environment. The rock has no energy on the ground, it's in a high entropy form (heat) in the surrounding area. While at the top, it's in a low entropy form (potential energy), and it's all in the rock. Since, due to the second law, low entropy systems evolve into high entropy ones (usually), we will see the rock falling more often then just randomly moving upward.

So, the point I'm trying to convey is this - if the reaction occurred one way, we know the total of all resultant forms of energy is equal to the total of all the forms of energy prior to the reaction. For the rock, we know that all of the above expressions are true. So, there was enough energy to get the rock to fall down. Therefore, there must be enough energy in the environment to get it back up, since all of the energy (kinetic) that it had when hitting the ground had to transferred int something else, no more, no less.

So, with the chemical reaction, we know that the energy needed for the reaction to occur one way must be the same amount needed for it occur the other way (if you record a chemical reaction on film, does playing it in reverse reveal any violation of the conservation of energy?). So, we know that the energy needed for it to occur is somewhere in the environment, either in the form of the resulting chemicals, heat, or whatever else you like. The key is just getting it back into the chemicals, so that they can do it in reverse. This is where the second law gets in your way, since the result of the reaction is a much higher entropy configuration, so getting it do anything is much more difficult.

Well, it wouldn't be for no reason. Since heat is just the non-mechanical transfer of energy due to a difference in temperature, we can imagine our rock regaining energy from the heat by having all of the excited air molecules (remember, temperature is just a measure of the average motion of the constituent particles) all simultaneously slamming into the rock, exciting the motion of its atoms, causing it to gain temperature, which may give it enough kinetic energy to rise up.

Once again, we see where the second law gets in the way - the chance of all of those particle simultaneously slamming into the rock is very, very small, so it won't happen very often.

Drakkith

I think you are missing my point Mark. I'm saying that to create energy we would need to have one of my examples happen, where we see rocks teleporting or flying back to their starting positions for no reason. Same for the CO2.

Mark M

I guess I am then. Are you saying that the rock spontaneously going up without first gaining energy (i.e. heat) constitutes a violation of the CoE? In that case you're right, I agree.

Perchie

The problem is caused by describing zero space as nothingness.

At t = 0, there was zero space – but (respecting the indestructibility of energy) zero space does not mean zero everything else ... indicating that energy (whatever it is) does not require dimensionality/space for its existence.

Drakkith

Exactly!

Drakkith

I'm not sure this is accurate. How can something exist if it has nowhere to occupy?

Farahday

The Univrse is 99.99% space by volume.

Mark M

Quantum mechanics forbids particles from being crammed into spaces smaller than their wavelength. Because Hawking's singularity theorems only use classical general relativity, it is assumed that whatever quantum theory of gravity is correct will prevent a big bang singularity. For example, LQG replaces the big bang with a 'bounce' type scenario. So, at no point was there 'zero space'.

Ms Music

I thought all the matter and energy of the universe were contained in a singularity, and that the big bang was merely a sudden expansion of this singularity into space and time? The energy and mass was always there?

http://www.physlink.com/education/askexperts/ae649.cfm

Perchie

At t = 0, there was no matter, space or time ... only an adimensional pure 'energy' potentiality.
Dimensionality together with this energy potentiality, created space-time and eventually, matter.

Since there was no space-time at t = 0, there was no before or outside it ... and the universe existed as pure, adimensional energy.

To exist before or outside t = 0 is impossible because there was no matter to allow the existence of anything ... there was only the energy potentiality.

You could argue that from t = 0, there is numberedness/dimensionality - and it 'sprang' from the numberless, infinite, adimensional totality of the energy potentiality.

Drakkith

Technically we don't know what happened at t=0, or if there even was a t=0.

Farahday

APPLAUSE....accolades....cheer...ROF

Even the TV science wizards like Michio Kaku have somewhat (but not entirely) backed off the notion that (if there was) a Big Bang initiated the phenomenon of existence.

Before something can change, before something can act or be acted upon, it must exist.

This is a rather simple axiom, intrinsically self-evident since any who might dissent must confess a belief in things that don't exist. Existence in the absence of change is possible but change in the absence of existence is not. The fact that existence is required in order for cause and effect to occur means change is derived from the phenomenon of being which, in turn, means existence is the source of cause and effect and not the result of it.

A cosmos finite in time or volume is quite simply illogical.