# Question - Energy

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#### sacr3

##### Guest
Where does the energy come from that drives an Atom? This question is probably one of the first things discussed amongst classrooms, etc. Unfortunately I haven't had the opportunity to discuss this topic as much as I wish I had, so far i've heard that we do not know where the energy comes from, or even what is really is (in terms of giving it a texture, if you wish)

Is this correct?

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#### drwayne

##### Guest
Can you take a moment and tell us what you mean by "drives an atom"?

Wayne

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#### sacr3

##### Guest
drwayne":ur4lsbgr said:
Can you take a moment and tell us what you mean by "drives an atom"?

Wayne
Well an atom is always moving isn't it? Cannot stop it at all (reach absolute zero) so what gives this atom its near infinant energy? Or am I incorrect about this, heh.

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#### MeteorWayne

##### Guest
Well, an atom doesn't have unlimited energy. It get's it from the kinetic energy that is delivered to it; i.e. heat.

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#### sacr3

##### Guest
MeteorWayne":2nk2nq76 said:
Well, an atom doesn't have unlimited energy. It get's it from the kinetic energy that is delivered to it; i.e. heat.
Ah, So basically all atoms are run by kinetic energy? Why can't we reach absolute Zero?

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#### MeteorWayne

##### Guest
Because in order to do so there can be no kinetic energy. That's the definition of absolute zero. Since everything that's above absolute zero has kinetic energy, you have to steal it away, which is very difficult as you get closer and closer to no KE. What do you do with the energy? How do you keep it from leaking back?

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#### DrRocket

##### Guest
sacr3":ser3c3vq said:
Where does the energy come from that drives an Atom? This question is probably one of the first things discussed amongst classrooms, etc. Unfortunately I haven't had the opportunity to discuss this topic as much as I wish I had, so far i've heard that we do not know where the energy comes from, or even what is really is (in terms of giving it a texture, if you wish)

Is this correct?
There are several aspects of an answer to your question, so bear with a somewhat long answer.

1. There is no energy required to drive an atom. An atom is not really just like a little solar system, but even with tht analogy no energy is required to maintain the motion. Energy is not required to maintain motion, unless there is a mechanism whereby energy is lost. The reason that your car burns gasoline all of the time is that it must overcome friction and air resistance, and because it goes up and down hills. Those things cause energy to be lost to the car and turned into heat. But think about the solar system and the planets revolving around the sun. They do not receive any additional push to keep them in orbit. They just keep going round and round, but because there is no frictional loss they need no new energy to continue that motion. That is the case with atoms as well. Within an atom there is no frictional loss, and no air resistance so the electrons electrons, proton and neutrons don't need a constant influx of energy to keep on doing what they are doing.

2. Atoms are build of elementary particles, the electrons are elementary. The protons and neutrons are composed of quarks. They are held together by the exchange of other elementary particles that create the forces that hold together the nucleus (weak and strong forces) and attract the electrons to the nucleus (electromagnetic force). All of those particles ARE energy. Whether you look at the theory of relativity or at quantum theories, a critical realization is that Einstein's equation E=mc^2 applies and tells us that matter and energy are really the same thing. So not only does the atom not require new energy to "keep functioning", it actually is itself just a form of energy. At the deepest level there is no difference between matter and energy.

3. Matter can be realized as energy. That is precisely what happens in a nuclear generating plant or a nuclear bonb. A little bit of the matter in the atom is released in the form of photons and heat when a large nucleus is split into a small one or when two light nucleii combine to form a larger one. There is no net gain or loss, just a change the form of the energy that was always there in the form of energy.

4. Energy can be transformed into matter. If you have two photons (light energy) that are of sufficient energy (high frequency) it is possible for them to interact and to form a particle of conventional mass. That is what is believed to have happened during the Big Bang. It also happens when light is shown on a material to heat it up. A photon hits an atom and is absorbed, which means that it provides its energy to an electron, the electron goes to a higher energy state within the atom, and that atom gains just a little bit of mass -- the mass associated with the energy of the photon which also obeys the equatin E=mc^2 (in the case of the photon the energy term E is also associated with the color of the light via E=hf where h is Planck's constant and f is the frequence of the light).

5. So basically the unverse is nothing but a big gob of energy. Some of it is in the form of ordinary matter, some of it is in the form of what is typically "energy" but it is all energy of one form or another. There seem to be some other categories that we don't understand very well yet, dark energy and dark matter, but they are still just types of energy. It is all energy, energy all the way down (turtles are energy too). So far as we know the energy content of the complete universe doesn't change, energy just changes form like a chameleon, but the total amount remains constant.

6. Your final question was something on the order of "Where does all this energy come from?". Well, it seems that the energy of the universe has been the same ever since the universe began. So, following that beginning there is no need for energy to come from anywhere. I is just here, doesn't change in quantity, but just keeps changing its shape. As to where the universe came from, that is indeed a mystery. We have some pretty good theoretical descriptions of how things worked immediately following (well a couple of billionths of a second after) the Big Bang itself. From that point on, our descriptions of the physical laws that govern everything are pretty good -- still not perfect and still being studied and improved, but pretty good. We have no idea of why the Big Bang occurred. In fact, since it appears that all space, all matter, all energy, and tme itself began with the Big Bang, physics cannot even begin to address that question, because physics itself began with the Big Bang.

Just like the rest of the universe, the energy necessary for an atom to function is in place inside the atom already, and it just keeps on humming, no additional fuel is necessary.

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#### DrRocket

##### Guest
sacr3":3u6c34ng said:
MeteorWayne":3u6c34ng said:
Well, an atom doesn't have unlimited energy. It get's it from the kinetic energy that is delivered to it; i.e. heat.
Ah, So basically all atoms are run by kinetic energy? Why can't we reach absolute Zero?
The inability to reach absolute zero is one of the laws of thermodynamics. That doesn't really answer your question though.

Absolute zero is the theoretical quantum state of lowest energy. In order for some bit of material to reach absolute zero, ALL of the enrgy above the ground quantum state would have to be taken from that material and it would have to go somewhere else -- to material somewhere else. So the material would have to interact with that other material in some way so as to allow the energy to go from it to elsewhere. But that contact allows energy to go in both directions, and energy tends to go from a place of higher energy to a place of lower energy. We are trying to get it to go the other direction in order to reach absolute zero in our little bit of material. To do that we actually have to use energy to force it to go in an unnatural direction. Here the nature of physics conspires against us and this has to be done in stages. We proceed a little at a time. What thermodynamics prevents us from doing is reaching a state of absolute zero in any finite number of stages. So we are prevented from reaching absolute zero in any finite period of time. Since none of us are patient enough to wait literally forever, we cant' ever get all the way to zero.

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#### sacr3

##### Guest
Well then, Thank you very much for taking the time to explain that to me! I appreciate this very much!

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#### astron_2007

##### Guest
energy is anything that has the abuilty to do work, so the realistic concept of this topic is that energy, is the universes main objective of life in the cosmos.

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#### MeteorWayne

##### Guest
The Universe has no objective of life. It has energy, and life is just part of that energy.

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#### michaelmozina

##### Guest
MeteorWayne":1x2ux8mn said:
The Universe has no objective of life. It has energy, and life is just part of that energy.
I suppose that all depends on how and *why* and *if* the universe was "created".

FYI, I very much liked DrRocket's explanation. Objects in motion tend to stay in motion. As far as we know, atoms remain stable forever unless influenced by some external force.

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#### drwayne

##### Guest
Slightly tangential note:

Note that there was a time, early in the period of the "solar system" model of the atom when
people noticed that the orbiting electrons, which by virtue of the fact that they were in
circular orbit were constantly accelerating, should in fact leak away energy through radiation.

This observation contributed to some of the ideas of quatum emission and absorption of
radiation.

Wayne

p.s. I love Star Trek, but I think it does lead to some issues with how people look at dynamics.
References are made a number of times to requiring engines to "maintain" a constant speed,
and there is of course the dramatic element that the minute that engines go off, the orbit begins
to drastically decay.

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#### MeteorWayne

##### Guest
Yes Star Trek always reinforces that misconception. If you are in orbit, you are in orbit; it does not need to be maintained by engines. It's one of the great pains that, especially, TOS has promulgated. And folks that don't understand real physics think it is true I'm surprised Roddenberry let that go just for the storylines.

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#### kg

##### Guest
Objects in motion tend to stay in motion.

Could someone please explain why the word "tend" is used? It seems like I've always heard it that way. Is that how Newton wrote it? Were there objects at the time that he couldn't explain changes in motion of? Was he leaving himself an out in case someone else found one?

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#### Mee_n_Mac

##### Guest
kg":1erfbqxw said:
Objects in motion tend to stay in motion.

Could someone please explain why the word "tend" is used? It seems like I've always heard it that way. Is that how Newton wrote it? Were there objects at the time that he couldn't explain changes in motion of? Was he leaving himself an out in case someone else found one?
According to the wiki the Latin went like :.

Lex I: Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare.

Which is supposed to translate into ....

Law 1 : Every body perseveres in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by force impressed.

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#### MeteorWayne

##### Guest
Indeed, based on that, and reality, the word "tend" is superflouous and misleading.

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#### derekmcd

##### Guest
MeteorWayne":lnohq8a3 said:
Indeed, based on that, and reality, the word "tend" is superflouous and misleading.
Don't confuse tend as a derivative of tendency. Tendency means a probability or an inclination where as tend has several different meaning. One of which is: "to move in a particular direction". Another example of 'tend' being used in physics is "tending towards infinity". For example: Once you pass the event horizon of a black hole, the geodesics tend towards infinity.

The statement, "... tends to stay in motion", could be reworded to state: "An object in motion moves in a particular direction to stay in motion, unless acted upon..."

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#### andrew_t1000

##### Guest
If absolute zero could be reached, would all the atoms collapse?
Is a material like neutronium possible?
What are neutron stars made of? Do they still have matter as we know it?

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