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Creation of Energy

  1. Dec 9, 2003 #1
    Hello,

    I am new to this forum so i'm not even sure if my question belongs here. Anyway, i am aware that the sun has the natural ability to create new kinds ot atoms throught it's gravitational force but can it or anything in this universe create Energy?
     
  2. jcsd
  3. Dec 9, 2003 #2
    My general thoughts on this is that energy can cannot be created from nothing. But, energy can be converted from one form to another, and energy can be converted from mass. Yet, the energy or mass being manipulated must already exist so in reality, no matter what one does, one is merely changing what already exists.
    The "new" creation of energy was likely done only once, during the creation of the universe.
     
  4. Dec 9, 2003 #3

    LURCH

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    Welcome to the Forums, Michael!

    This question is going to get into definitions a little bit. You see, the Sun doesn't actually "create" new kinds of atoms, not by the traditional use of that term, at least. It assembles them by taking already existing atoms and putting them together in new configurations. But the law of conservation, which states that energy can neither be created nor annihilated, uses the word "created" in the more literal sense; to bring something into existance ex nihilo(out of nothing).

    In this sense, the answer to your question would be: No, neither stars nor any other known phenominon can create energy. And, since matter is made of energy, it cannot be created or distroyed, either. Matter and energy can only be rearanged; converted from one form to another, assemblerd, dissassembled, etc.
     
  5. Dec 9, 2003 #4
    I always thought that but tell me if you can that if enegy cannot be created then how did we come to be? (In nice voice)

    I would expect that energy would have to be created somehow - leading back to the big bang no doubt.
     
  6. Dec 10, 2003 #5

    turin

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    So, what about a random quantum fluxuation? If some system, say a HO, is not in an energy eigenstate (you measure the position , and the position operator does not commute with the Hamiltonian), how can one even talk about conservation of energy?
     
  7. Dec 10, 2003 #6

    russ_watters

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    It is true that in general classical physics breaks down on a quantum scale.
    Thats complicated, but essentially, when the universe was created, it had all the energy in it that it has now. It doesn't violate conservation because there is no "before" state with which to compare energy levels. Thats part of the Big Bang theory.
     
  8. Dec 11, 2003 #7
    Energy had to come from somewhere even if it were from Hyper Space or an Alterate Reallity it still must have some from somewhere (STill in nice voice)
     
  9. Dec 11, 2003 #8

    turin

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    Why? Conservation of energy will never be anything more than a model, albeit I must admit that I put more faith in that model than in almost any other.
     
  10. Dec 11, 2003 #9

    chroot

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    darklyzhadowed,

    One physicist actually went so far as to describe questions like as existing in something he called "Bubble Land." Questions in Bubble Land simply have no answers right now. They are the questions at which physics and philosophy meet.

    We don't really know the answer to your question: where did the energy for our universe come from? It is entirely possible that we will never know the answer to this question, because we cannot escape our own universe to see if there is actually something "outside" it. It is possible that our universe is just a quantum fluctuation, and all its energy has been borrowed (temporarily) from the vacuum, in the same way that virtual photons produce and disappear constantly in a laboratory vacuum.

    Don't be dissuaded in your interest in science because we can't yet answer your question -- there are lots of fascinating things we can say about your question, but we may never be able to assign it an answer.

    - Warren
     
  11. Dec 14, 2003 #10
    gamma rays passing close to an atomic nucleus can create an electron positron pair. It might therefore follow that energy was not just created from nothing but there becomes from nothing a positive and an equal but opposite negative. If a positron encounteres an electron they anihilate, or become nothing again giving off a photon.
     
  12. Dec 15, 2003 #11

    turin

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    I wouldn't say that this demonstrates something coming from nothing, at least not without mentioning that the gamma ray ceases to exist, and so, at the same time, something became nothing.




    Where did the photon come from?
     
  13. Dec 15, 2003 #12

    jcsd

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    You have to ammend the conservation so that [itex]\Delta E\Delta t \geq \frac{\hbar}{2}[/itex] is remembered. Superposed states aren't a problem as the wavefunction shouldn't be given direct physical signifcance in the conventional interpreation of quantyum measuremnt.
     
  14. Dec 15, 2003 #13

    turin

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    Are you suggesting that, even in the context of QM, since [itex]\Delta E\Delta t \geq \frac{\hbar}{2}[/itex], then the amount of energy that should be accounted for couldn't have come from a quantum fluxuation, because this energy has been around a lot longer than the [itex]\Delta t[/itex] that this relation allows? I have never been comfortable with this relation. Can you explain where it came from?




    That is highly subjective. What do you think the conventional interpretation of QM is?
     
  15. Dec 16, 2003 #14

    jcsd

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    You just have to take into account that energy obeys an uncertainty relationship and it's only conserved within the limits allowed by this uncertanity relationship. For example you can think of quantum mechanical tunelling as a particle borrowing energy within the limits of uncertainty, but if you were to actually perform a measuremtn on a particle it would never have an energy that violates the conservation of energy. Simlairly if you were to perform a measuremnt on a superposed state your results would never violate the conservation of energy.

    The convential interpretaion is the Copenhagen interpretaion suitably adjusted to allow new concepts in quantum measurment such as decoherence.
     
  16. Dec 16, 2003 #15

    turin

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    I guess I just don't understand that uncertainty relationship. Can you explain it to us?

    Another thing I just realized. This so called uncertainty relationship seems to suggest that there is no problem with an infinite uncertainty in energy. So, I think that just about puts us where we are now. How certain are we of the amount of energy there is in the universe? I am personally just about infinitely uncertain. But according to the uncertainty relationship provided, that's OK. Because I've lived for some number of years, and my uncertainty of the total energy of the universe is huge, so these two factors are in agreement with this uncertainty relationship. Am I misinterpretting?

    I do not at all see what this has to do with energy conservation.




    Why would I think of it that way? The QM wavefunction extends to regions of space where classical particles have zero probablity to exist. I don't understand "borrowing energy within the limits of uncertainty." Can you elaborate this borrowing process?




    I agree, but I didn't mean that there would be a violation of energy conseration. I meant that energy conservation just doesn't make sense to me in the case of a superposition of energy eigenstates.

    For simplicity, let's say that a system is in a superposition of 2 energy eigenstates, ψa and ψb, with nondegenerate eigenvalues, Ea and Eb, respectively. Lets say that the superposition is:

    ψ = (ψa + ψb)/√2.

    If I measure the energies of some number of these identical systems, then half of the time I will find that the energy is Ea and half of the time I will find that the energy is Eb. It's not that this amount of energy was conserved or something. We can't really say anything about the particular amount of energy of the system until we make the measurement. So, that's why I'm saying it doesn't really make sense to me to speak of energy conservation in this case.




    It is my experience, as well, that the Copenhagen interpretation is the conventional one. I don't know anything about decoherence (I don't even know what it means), though, so I guess that disqualifies me from much of the discussion.
     
    Last edited: Dec 16, 2003
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