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Matter = E ?

  1. Feb 23, 2007 #1
    I would like to know whether matter is energy? Does Einstein's formula, E=MC^2, prove that matter is nothing more than energy... all the atoms, the table in front of you, the views from your window, and the air you breathe are just different configurations of the one fundamental property: energy?

    Immediately after the big bang there was just energy, right? Everything else came later... from energy.

    So, perhaps matter can’t be destroyed, but simply converts back to a less dense form of energy?

    What do you think?
  2. jcsd
  3. Feb 24, 2007 #2

    Meir Achuz

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    E equals m (with c=1) for a particle at rest. This does not mean they are the same thing. For a particle with velocity, E increases while m is invariant.
  4. Feb 24, 2007 #3
    Well, the straight forward answer to your question is most definitely no!

    I'll post the thoughts of one of our finer mentors for your physical considerations:

    Also, if we can say [tex]e=mc^2[/tex] means mass IS energy, then why not interpret the "=" (equal sign) in [tex]F=ma[/tex] to mean, force IS mass? I don't know if many people would accept that interpretation.
  5. Feb 24, 2007 #4
    But if we could say F=mXconstant, we might say "force is mass." By "is" we probably would mean "equivalent," as we do with energy and mass.

    Since acceleration is not a constant in F=ma, we can't make the corresponding identification.

    Different forms of energy occur elsewhere in Physics. In thermodynamics, work and heat are equivalent to energy in a manner similar to mass and energy. Sometimes we do say work "is" energy.
    Last edited: Feb 24, 2007
  6. Feb 24, 2007 #5
    I agreee. Just because E = mc2 this can't be taken to mean that mass is energy, only that an amount of energy absorbed or emitted by a body will increase that bodies mass according to that equation. Otherwise you could interpret the expression for a photon E = hf as meaning that energy and frequency are the same thing, and that'd be just plain silly.

  7. Feb 25, 2007 #6
    Thanks for the responses. I'm surprised that this question gets so many different answers from all the physicists I ask. Most here said no, yet many others believe matter is energy.

    It's a little confusing that Einstein summarized his theory like this:

    "It followed from the special theory of relativity that mass and energy are both but different manifestations of the same thing — a somewhat unfamiliar conception for the average mind. Furthermore, the equation E = mc², in which energy is put equal to mass, multiplied by the square of the velocity of light, showed that very small amounts of mass may be converted into a very large amount of energy and vice versa."

    Could someone explain what he meant, if not that matter = energy?

    Interestingly, he also said "“I believe in Spinoza's God, Who reveals Himself in the lawful harmony of the world, not in a God Who concerns Himself with the fate and the doings of mankind.”

    Spinoza's philosophy states that everything that exists in Nature/Universe is one Reality (substance) and there is only one set of rules governing the whole of the reality which surrounds us and of which we are part. Spinoza argued that God and Nature were two names for the same reality, namely the single substance.

    Sorry to bring God into it, but thought the second quote pertained to the discussion (regarding Einstein's meaning for his first statement).
  8. Feb 25, 2007 #7


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    If your intention is to seek a physics answer, you already got it. If instead, you're seeking a philosophical discussion, this is the wrong forum. Please start another thread in the Philosophy forum, or I can move this thread there.

  9. Feb 25, 2007 #8
    Sorry, ZapperZ. Didn't realize there was a philosophy area here at physicsforums. I would have asked there had I known.

    The original question seems to generate both yes and no responses; from a purely scientific point of view, it's is worth further discussion/input. So, as long as philosophy is kept out of it, I can see no reason to move the thread.
  10. Feb 25, 2007 #9
    Mass is not the same as matter. Mass, like energy, is a property of matter. Mass and energy are sort of equivalent by E=mc^2, but there is more to matter than mass/energy.
  11. Feb 25, 2007 #10


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    But you seem to have missed the meaning of the responses. You'll see that in many cases, a "yes" has a "qualification" to it. For example, if you take something, smash it into bits, cook it, and turn it into something else, is that thing STILL the original object that you started with?

    The problem here is that it appears you didn't understand the issues that someone quoted me earlier. You simply cannot just use ONE criteria (i.e. the energy equivalent of mass) and then go blind about the rest of its properties. It's like saying "Oh, it has the color of purple, so it must be Barney". You missed the fact that it is edible, it has a different taste, and that it is a beet! I listed several other properties of "mass" and "energy" that are not compatible with each other, but somehow those are ignored.

    Just because something can be converted into something else, does not mean that those two are identical. People never confused "force" with "mass" in F=ma, or current is identical to potential difference in V=IR. Yet, they want to do that with E=mc^2, just because you can write that equal sign.

  12. Feb 25, 2007 #11


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    Perhaps you are harboring some misconceptions here but I am yet to see a 'yes' response.

    Edit: Zz beat me to it.
  13. Feb 25, 2007 #12
    This question does seem to be more about the use of language than about the use of physics. If it is to be kept in the realm of physics, then the way to define energy, mass, or any quantity that enters the equations is in terms of how it is measured. This use of operational definitions is what ties theory to the physical world. If energy and mass were really the same, i.e., measured the same way, there would be no need for an equation to connect them.

    Hmmm. This still feels like a philosophy discussion.
    Last edited: Feb 25, 2007
  14. Feb 25, 2007 #13
    "For example, if you take something, smash it into bits, cook it, and turn it into something else, is that thing STILL the original object that you started with?" ZapperZ

    That's probably not the best analogy Zz. It's not the original object, no... the original atoms have undergone changes, molecular configurations have altered... and some have even left the building... but the electrons, protons and neutrons are still electrons, protons and neutrons...

    The 'yes' answers I spoke of have come from other forums. I haven't discounted what you're saying, on the contrary: I've found it very interesting. No need to expell "negative energy"...
  15. Feb 25, 2007 #14
    Perhaps you should move this to the philosophy forum if it bothers you so much, that was never my intention...
  16. Feb 25, 2007 #15


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    But it is no longer the IDENTICAL THING. Something has been "coverted" into something else. Why people simply don't want to accept that, I am very puzzled.

    Sorry, we don't do "other forums" on here. If we entertain every single thing said on "other forums", we'd be swamped with correcting a lot of mistakes and nothing else. PF is not unlike any other, and I should know since I've been on the 'net since 1989. You'll find that we have a significantly higher signal-to-noise ratio.

  17. Feb 25, 2007 #16
    'Energy' might be having a doubt on HOW mass is converted to energy
  18. Feb 25, 2007 #17
    And I thought mass was the property of a physical object that quantifies the amount of “matter and energy” it is equivalent to.

    I know that m doesn’t equal E… I know this because m=E/c^2

    My question was, does "matter" (not mass) equal E, is matter dense energy?

    But, considering you know everything (with a healthy dose of arrogance thrown in), perhaps you could explain how the universe began as energy and matter magically sprang from it...

    I suppose there is a special “quantum physics forum”, too?
  19. Feb 25, 2007 #18


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    Nope. Unlike you, I'm not smart enough to know the difference between "matter" and "mass". Maybe you'd care to enlighten me on what you define as "matter" and how you would quantify such a thing.

    I'm sure even you could have answered such a thing.

  20. Feb 25, 2007 #19
    Didn't think so. I made that deduction when you started getting rude... it's a natural progression...

    That's what I was asking the good people here. I thought it'd be obvious that I wouldn't have come here to ask the question if I knew the answer...

    According to "our" terminology the words ‘matter’ and ‘energy’ are different; hence, we do not see them as the same thing… but that doesn’t mean they aren’t. My discussions with other physicists have made me aware of this possibility...

    Quote: "Space has those properties, and you can consider energy to be a stress in some volume of it. This stress won't "stay still" unless it's traveling in a circle, whereupon it's matter, and it can hold some other stress still."

    If it was universally known that matter isn't energy, then why do so many seemingly astute physicists think it is? There must be a possibility, at least... Therefore, not such a ridiculous question.
  21. Feb 25, 2007 #20


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    Let's make one thing clear here, I wasn't being "rude". You were making a number of statements to counter what you were told in this thread, and I merely, in turned, questioned what you said. Somehow, challenging your perceived notion is now being 'rude'.

    But you already are making a distinction between "matter" and "mass". As far as I can tell, you are making such a distinction for the first time. Is this something you got from "the other forum" also? Therefore, it is FAIR for me to then ask you on how you define such a thing. I never made such distinction, and as far as I know, in physics, such a thing is never made also.

    This makes no sense. Who are these "other physicists"? Did you misinterpret what they were saying the same way you did here? Did they indicate to you that they often simplify their equations by letting c=1 and thus, E=m?

    We cannot carry any rational discussion simply based on hearsay, and simply based on us trying to "translate" what you heard elsewhere. Please make more definite citation. If not, we will always try to argue against these phantom sources that may not even exist.

    I would say that there is a huge amount of background knowledge that one needs to know before one start using the "stress energy tensor" in here, don't you think? Or else, you are simply quoting something you did not understand.

  22. Feb 25, 2007 #21
    I'm sorry to see how this discussion is going. It started out pretty interesting.

    The distinction between matter and mass is a legtimate question, although I, too, am not able to answer it. It may be as simple as: mass is a property of matter.

    Again, is this physics or philosophy?
    Last edited: Feb 25, 2007
  23. Feb 25, 2007 #22


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    It might be. But if you notice, that isn't the original question. The distinction between "mass" and "matter" is only made recently, not in the OP. I have no knowledge to be able to separate out "mass" from "matter", and as far as I know, I haven't seen anyone else who can.

    There is a reason right now why this isn't moved to the Philosophy forum, but it isn't something that can be discussed right now.

  24. Feb 25, 2007 #23
    I simply reached the conclusion (right or wrong) that a distinction between "mass" and "matter" was necessary for matter= E, while keeping the two inextricably linked (i.e. assuming mass could represent the density of energy/matter).

    Zz, as I said before, my intention was never to offend. I didn’t profess to be an expert; I imagined that was clear by my lack of understanding. My innate curiosity is the only impetus for asking these questions, not for the love of argument itself.

    The word ‘God’ was used once in my posts in an attempt to qualify the meaning of Einstein’s previous statement; and, after having been met with opposition, I was more than happy to continue the discussion from a purely scientific standpoint, as mentioned.

    Philosophy isn’t automatically necessary for my questions about energy, matter and mass, is it? I had the crazy idea that finding a complete understanding for these three things, and discovering a single fundamental property from which everything is made would be akin to the Holy Grail in physics. Again, my comparatively minuscule knowledge on this subject was the reason for such a misconception. My sincere apologies.

    I do hope the discussion continues, though (on a more amicable tangent, of course!), and will try to remain a silent participant…
    Last edited: Feb 25, 2007
  25. Feb 25, 2007 #24


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    Let's go back to basics. Zz tried to make this point, but you seem to have missed it.

    Suppose c=1, as can easily be done by playing with your units.
    Then, E=m.
    This does not mean that matter and energy are the exact same thing. Rather, it means that a certain amount of mass can be converted into the same amount of energy.
    There's nothing more to it.
  26. Feb 25, 2007 #25
    Thanks. I imagined that the reason for multiplying mass by c^2 may have been due to energy traveling at the speed of light. An erroneous assumption derived from the above idea that energy may travel in a circle (thus, appearing to “stand still”) forming matter (dense energy) in the process… and I stupidly thought the reason for squaring c was that, when matter was created, the energy was traveling in another direction at the speed of light also... as the universe expanded...

    (and, what would a perfect theory be if not concise: gravity was the force created by this “alteration of state”… a force which travels at c... can you tell I write fiction?)

    As I said, I best shut up and leave it to the experts :blushing:
    Last edited: Feb 26, 2007
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