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Do we have a theory as to what energy is?

  1. Apr 22, 2014 #1
    Atoms I know Strings I know. these are the things that energy operates in. If we were to be able to make a atom or a string large enough to hold in our hand and pull it apart to smaller and smaller pieces would we begin to understand what energy really is. We know all the aspects of energy But do we understand what energy is . I read that there are only two things matter and energy. to my understanding that is not true. There is only energy formed or molded in cohesive ways to represent matter. From atoms to strings to the nose on my face there is only energy, is this correct.
  2. jcsd
  3. Apr 22, 2014 #2
    Energy is not as mysterious or fundamental as you are making it out to be. Energy is just a number you can calculate. It is a useful number because if you calculate the energy of a physical system at two different times, you will get the same number, no matter what has happened to the system in the meantime. Because of this we say that energy is "conserved." We understand the deep reason for this: it is because the laws of physics do not change in time. For any physical system whose governing laws are constant in time, there is a number you can calculate which is conserved and plays the role of energy. The mathematics behind this is called Noether's theorem.

    Energy is not a mysterious substance that makes up everything. It is just a number.
  4. Apr 22, 2014 #3


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    This is rather puzzling and odd.

    We can measure energy. We in fact use it every single day. It is an inherent ingredient in our description of our world.

    Strings, on the other hand, is still highly hypothetical. It has not experimental evidence, and there isn't a single, agree-upon theory.

    Yet, you claim to "know" strings, and don't understand energy. This doesn't make any sense to me. You might as well claim that you know about ghosts, but airplanes are mysterious to you.

  5. Apr 22, 2014 #4
    I meant to imply string theory is a theory of what is smaller than atoms. In short I know of the string Theory. As to Noether's theorem this is describing the actions of energy not what energy is. Does anyone get the concept of this question. I would like some real feed back. Lets just say vibrating strings are the smallest form of energy of which every thing else is made ,quarks, atoms, us everything. Still the question is what is energy. To tell me Noether's theorem is energy is like looking in a dictionary reading the definition of energy and saying, oh that's what energy is.
  6. Apr 22, 2014 #5


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    Yes, we get the exact question every few months it seems. So we all get it. The question is a reflection of a discomfort people have with the concept of energy. For whatever reason, people want there to be some deeper meaning to it and just can't accept that it is nothing more than a defined property that people discovered was useful a while back and happens to be conserved in a wide variety of circumstances. Or to put it another way: there doesn't need to be a theory: energy is just defined.

    For some strange reason, people never ask the same question about velocity. They just accept what velocity is at face value.

    I'm sorry, but unfortunately your choices are to accept what energy is at face value or search endlessly, in vain, for something more that doesn't exist.
    In general, that's what definitions are for: They are descriptions of what words mean/things are.
  7. Apr 22, 2014 #6
    Asking what something "is" in physics (or science) is problematic and not generally insightful. Energy is that which has the units of joules (or kg (m/s)^2). Energy is that which is conserved via time symmetry of physical laws (per noether).

    When trying to understand what anything "really is" the only way to do that is with a collection of properties about that thing. What energy "is" is that which has certain properties...

    Your comparison to the dictionary is not completely inaccurate. All words are defined by other words and you can only get a sense of the language and meanings of words after relating many of them together. Similarly, all scientific concepts and entities are defined in terms of other scientific concepts and entities. You can only get a sense of their meaning by relating them to each other.
  8. Apr 22, 2014 #7
    We have a understanding of what velocity is. Just as we understand what water is. To take it further saying how water acts is not saying what water is. But water is made of atoms and atoms are made of energy which no one knows what it is. I was just wondering If anyone anywhere has a guess as to what energy actually is since it makes up everything.
  9. Apr 23, 2014 #8
    The atoms are not made of energy. No more than they are made of velocity, momentum, force, etc.
    The atoms and its components may be described by these physical quantities but to say they are made of energy is as saying humans are made of length. Or weight.

    But maybe you can explain what velocity really is, if you think this is a well understood point.:smile:
  10. Apr 23, 2014 #9


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    Actually, the most accurate way of saying what something is, is to give a complete description of its properties and how it acts.

    I agree with Nasu's post on this. Atoms are not made up of energy. It is true that certain reactions can release energy, but this does not mean that the atoms are made of energy.
  11. Apr 23, 2014 #10
    Energy may turn out to be better described as an emergent property of a more fundamental description of nature. It's all very new stuff, but you may wish to learn about the Holographic Principle. The origin of which was from string theories, but could be applicable to other descriptions of quantum gravity.
  12. Apr 23, 2014 #11


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    We have an understanding of what velocity is, because we defined what velocity is: How to measure / compute it.

    The same with energy. Just that energy is more generally applicable, as it comes in different forms and therefore there are multiple definitions.
  13. Apr 23, 2014 #12
    Craigi yes I agree . the holographic principle is very interesting as well as the simulation theory of nick bostrom. What if energy its self is intelligent and the only simulator is energy its self. I've not seen any theory that gives energy conscious intelligence but but since everything is energy,it seems this may be plausible. Things like the double slit theory, and others imply that energy reacts to observation and behaves different at those times.
  14. Apr 23, 2014 #13
    A.T. its not the same.
  15. Apr 23, 2014 #14
    Someone else brought velocity up, I was just responding to them.
  16. Apr 23, 2014 #15
    [my bolding]

    Bostrom's simulation argument is philosophy rather than physics, but does have some grounding in multiverse theories. You would need to find a way to connect the argument physically, to discuss it here. I don't know of any paper that does so, but I wouldn't be suprised to find that Tegmark has published something to that effect. Guth has also explored the theoretical implications of how one might go about creating universes.

    You can't just throw in terms like "any theory that gives energy conscious intelligence" then expect people not to object. Firstly, it doesn't have any (obvious) meaning. Secondly it sounds like you're trying to make physics fit a preconcieved notion of reality.
    Last edited: Apr 23, 2014
  17. Apr 23, 2014 #16
    Atoms are made of energy and everting below an atom is made of energy.
  18. Apr 23, 2014 #17
    Maybe, I was just doing a little SciFi type speculation as to energy and intelligence.
  19. Apr 23, 2014 #18
    Physics sprang from philosophy after all. They are not totally different.
  20. Apr 23, 2014 #19


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    Have you, perchance, read the forum rules regarding unsupported claims, personal speculation and philosophical discussion?
  21. Apr 23, 2014 #20


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    Of course not. The definitions of velocity and energy differ. But in both cases they are human made definitions, which say what velocity and energy are.
  22. Apr 23, 2014 #21
    String theory speculates vibrating strings of energy are what atoms are made of.
    If you have philosophy that the earth revolves around the sun. Then you prove your theory by physics.
    But oh please forgive the SciFi energy intelligence reference. Bandersnatch.
  23. Apr 23, 2014 #22
    Nevetheless, you should read the forum rules.

    Under the traditional definition, physics is a subset of philosophy. A more contemporary definition, defining academic disciplines, renders them as distinct subjects. Inevitably, there are areas which do crossover, but the forum is for discussing physics. Bostrom's simulation argument is better described as metaphysics. That isn't to say that we can say with certainty cosmology will never apply it, but without a physical reason to do so, it remains philosophy.
  24. Apr 23, 2014 #23


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    So, what is velocity?
  25. Apr 23, 2014 #24
    A seemingly magical quality possessed by objects which causes them to continuously disappear from one location and reappear in another.
  26. Apr 23, 2014 #25
    Einstein/Poincare conversation

    With respect to everyone involved in the above discussion upon energy.
    I add a little light hearted banter with an air of philosophy:

    'You know Henri, I once studied mathematics, but I gave it up for physics'.

    'Oh, really, Albert, why is that?'

    'Because although I could tell the true statements from the false, I just couldn't tell which fact were the important ones.'

    'That is very interesting, Albert, because, I originally studied physics, but left the field for mathematics.'

    'Really, why?'


    'Because I couldn't tell which of the important facts were true.'

    The definition of energy has been very well discussed, illuminating(!) and highly enjoyable.

    Planck's pivot: hv=E=mc^2 (v=f=frequency).
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