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What is energy made of?

  1. May 19, 2006 #1
    Can anyone please tell me what energy is made of? If this is a really bad question please feel free to eliminate this thread... sorry to bother!
  2. jcsd
  3. May 20, 2006 #2
    Not a bad question at all.

    I don't think anyone really knows. Someone I knew said energy might be the manefesation of a certain configuration of space-time and the limited set of rules it can go to change. But then what is space made of?

    Eventually it's going to boil down to something fundamental that isn't made up of anything else but itself.

    So in short energy is made up of energy. You've got to stop somewhere.
  4. May 20, 2006 #3


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    Why do some teachers always tell me that energy is simply a mathematical quantity that we use to help calculate things? It seems to me that energy is much more fundamental than that. Perhaps energy is the purest component you can ever get. That is, energy is not made up of anything else.
  5. May 20, 2006 #4
    So energy could be considered as an element but energy may or may not be a compound.

    gold as an element is practically considered made of itself but it is a compound


    Is there a motivating force behind energy? It would probably be an even more elusive "object" of study judging from how energy has already proven to be a slippery subject of inquiry... with regard to origins.
  6. May 20, 2006 #5


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    Energy is a property of a system, not a substance with an independent existence. You might as well ask "what is length made of?" or "what is momentum made of?"
  7. May 20, 2006 #6


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    This is THE best response for this type of question. It illustrates clearly one of the things that we have to deal with in physics - what is the appropriate question to ask of Nature. This is because meaningless question will give you meaningless answer that doesn't add to your understanding of what is being studied.

  8. May 20, 2006 #7
    My question only seems meaningless if the meaning of my question escapes you as it does me. The meaning of my inquiry escapes me and that is the motivation behind my inquiry.

    Are there other examples of properties whose origin and composition are a mystery?

    How else can I ask "what is energy made of and where does it come from? Is it taboo to ask this sort of question? Is it impossible to answer? Or is it as ridiculous as asking "what are the origins of nature?"

    One thing I can assure anyone of is that I am not leading you toward a sermon on the nature of metaphysics or the futility of the study of physics. I am simply finding out if there have been any studies on the nature of the origin of energy.:confused:

    PS. I have a feeling I've posted the wrong formula for the composition of gold. If so, please ignore the post!
    Last edited: May 20, 2006
  9. May 20, 2006 #8
    Here's a most intelligent way of re-phrasing Bohr's idea that what science says about nature has little to do with what nature is.

    Please consider this quote:

    With acknowledgements to "Moving Finger".

    So, I suppose my question stands outside of the limits of the intelligible. However, if one doesn't make a stand somewhere, one really doesn't learn anything.
    Last edited: May 20, 2006
  10. May 20, 2006 #9


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    quantumcarl, I quote a text by Feynman which should give you a hint of why your question can be considered meaningless.

    The quote is from part of the text at
    under Life&Science, What is science?

  11. May 20, 2006 #10
    Hey, Phoenix. 'Tis Icantthinkofaname from totse. Good to see you here.
  12. May 20, 2006 #11


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    You are confusing the reponse that the question is "meaningless" with a criticism. It isn't! To say it is meaningless literally means what it says - the question has no meaning.

    So the response you got was an explanation on why it can't be answered, NOT a criticism that it shouldn't be asked. Do you see the difference?

    I brought up another example a while back when people asked for the size of a photon - it is something a photon was never defined with. As with jtbell, I also brought up an analogous example of asking for the color of pain, for example, or something equally "meaningless". So asking something of which it was never defined with (see jtbell's example of what asking what is momentum made up of) can lead to non-meaningful answers. It isn't a criticism - it is an explanation.

  13. May 20, 2006 #12
    i think energy is just mathiematical quantity
  14. May 20, 2006 #13
    It's origin and composition aren't entirely mysteries. Energy is one of the few things that are conserved for closed systems. So when we are doing calculations, it often helps to know what the energy is. That's not a great way of putting it, since one may ask, "What is a closed system?"

    But the answer to that question, while it is in fact very subtle, is more or less what you think it is.
  15. May 20, 2006 #14
    What is energy ? E = M c^2
  16. May 20, 2006 #15


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    I concur with Zz about the meaninglessness of the question (in the sense that he explained: not a criticism). The question "what is energy made of" implies several premisses that are not true. The question "what is X made of" has a meaning in the following sense: X can be seen as a collection of other things Y in a certain structure, of more fundamental nature, such that by considering things Y together, we understand aspects of the behaviour/appearance... of X.
    This is what happens when you say that cars are made of mechanical and electronic pieces of equipment, that wood is made of organic fibres, that a block of iron is made of iron atoms...
    But this hierarchical structure does not always hold, for all concepts, and for these concepts, the question then becomes meaningless, like: "what's the CPU clock speed of a bucket of water" or something.
    Now, maybe one day we might have a formulation of nature in which, what we now call "energy" is in the end, represented by a hierarchical structure of some kind, and then the question might have a meaning. Or maybe not. But, energy being a *theoretical concept*, its only existance being made up of its theoretical definition, and not corresponding to something "out there", as it stands, as a theoretical concept, it has not more meaning to ask "what is energy made of" than to ask "what is diameter made of".
  17. May 21, 2006 #16


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    I really like the "energy is a property of the system" answer. That really does explain it best.
  18. May 21, 2006 #17
    So that, when measuring amounts of energy with say, calories or gigajoules or Mc2 we are only measuring a theoretical concept?

    Is this similar to the measurment of other things like light in "photons"... gravity in "gravitons"? Is this all theoretical terminology and nothing more? Ee ghads.

    No criticism taken. Thank you all for your interest in this idea.
  19. May 21, 2006 #18
    I prefer the "energy is a property" idea.

    Just like "time" and "space" are properties. We do not say that "time is made up of time", nor do we say that "space is made up of space". Time and space are properties of the world, that we measure by the way that we interact with the rest of the world. Energy is in the same category.

    Best Regards

  20. May 21, 2006 #19
    Is energy then only a property of a Dynamic system? Times arrow and all that ;)

    I have allways looked at it as a numerical value representing change, in that energy quantifies work or change. I like the information theory point of view more and more though. E=mc^2 is obviously etched into my mind also.
    Last edited: May 21, 2006
  21. May 21, 2006 #20
    Energy is a quantity that describes motion. Whereas the vector quantities velocity and momentum compare motion over distances, the scalar quantity energy is needed to compare motion over time.

    Energy measures motion, but in a different way than momentum does.
  22. May 21, 2006 #21


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    In order even to say that you "measured an energy", you need a theoretical interpretation of your measurement.
    (and yes, photons and all that, you also need a theoretical interpretation).
  23. May 21, 2006 #22
    I suppose that the energy is the quadratic characteristic on the coordinates and momentums of the isolated system that doesn't change in the space and time.
  24. May 21, 2006 #23
    Thanks vanesch. I get that inches are a theoretical measurment or cubits in that they are decided upon arbitrarily or with reference to something else like an actual object for instance a "foot". This is why it gets confusing for me because I don't know what the physical reference material for a "photon" or a "graviton" is... or, for that matter, a calorie and so on.

    If energy is a physical property does that mean energy itself is physical or is it an aphysical, theoretical property of a physical condition?

    For instance, a property of water is that its wet. "Wetness" is entirely dependent on water. But it is a property that can only be determined in comparison to "dryness". Is the property of energy only determinable by comparison to a lack of energy or, perhaps when its compared to "entropy"?

    (edit) Light and heat are properties of fire and energy is a property of both light and heat. Both light and heat have no mass yet energy remains as a property of them.

    If Energy = Mass and light squared does that mean energy is as physical as mass and light or is the equivilency meant to be theoretical in terms of measurement?

    Light has only what physicists call "relative" mass yet, apparently, energy is a property of light. I suppose this is why light is included in Einstein's equation.

    Does the "relative" in "relative mass" refer to the fact that when light is occuring there is "something" occuring... as compared and relative to nothing occuring at all?

    (Please forgive my ignorance to do with this subject)
    Last edited: May 21, 2006
  25. May 21, 2006 #24
    The problem with this question is that it presupposes that energy is something, and that this something can be made of something. These presuppositions are both wrong.

    Having been told that, you should now be asking yourself "so what IS energy?" Which is both a better question, as well as an answerable one.

    Energy is that quality of a phenomenon that enables change to occur. In other words, energy is not a thing unto itself, but rather a word we use to refer to the ability of a system to change. The more something is able to change, the more energy we say it has.

    All the different kinds of energy you hear about (potential energy, kinetic energy, vacuum energy, zero-point energy) are just different ways of talking about the same thing.
  26. May 21, 2006 #25


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    You throw a ball to someone else. Is the motion of the ball physical? Yes in the sense that it is completely the property of a physical thing and is produced by physical causes. No in that it is not itself a physical thing.

    Hold that thought; energy has something of the status of motion, and you can use insights about motion to suggest ways to think about energy.

    Now ask your question about motion; what is motion made of? Are there atoms of motion? Evidently motion can be made as small (in distance or speed) is you like, even the Planck length isn't literally a lower limit, it's just that mysterious things that physics doesn't yet understand happen when things get that small. Same with energy; QFT says an electron can emit a photon of arbitrarily low energy (=arbitrarily long wavelength). So it doesn't look as if either motion or energy can be thought of as made of standard pieces like "atoms".

    Suppose I suggested that all energy comes from
    1) Motion of particles, and
    2) Emission and absorption of particles.

    Would anybody (at least any quantum partisans) disagree?
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