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B What came first, matter or energy?

  1. Aug 7, 2016 #1
    I don't know if this question is even relevant, but I wonder about it so I'm asking it.

    I understand from GR that matter and energy are essentially interchangeable, that matter can be converted to energy and vice versa.

    I also understand that the earliest "snapshot" of our cosmos (via the background radiation) was a plasma of matter and energy. But, if I understand everyone correctly, we predict that this plasma came from the annihilation of matter and antimatter. So we began with matter and antimatter, then that was converted into a plasmic mixture of matter and radiation.

    So am I correct in saying that energy came from matter?
     
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  3. Aug 7, 2016 #2

    Drakkith

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    The plasma was composed of matter, antimatter, and radiation, and would have had plenty of energy at the same time. Note that energy is a property of matter and fields, it is not something in and of itself.
     
  4. Aug 7, 2016 #3

    Orodruin

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    Energy is a property of matter, just like momentum. Like other energy forms, such as kinetic and potential energy, mass energy can be converted into other forms of energy. You cannot convert mass to "pure energy", there is no such thing.
     
  5. Aug 7, 2016 #4
    'Matter' in the usual sense of the word means stuff made of atoms.
    The first atoms were hydrogen and helium, probably a small amount of lithium.
    These atoms could not exist until the original hot plasma Universe had cooled (and expanded) considerably.
    https://en.wikipedia.org/wiki/Big_Bang_nucleosynthesis
     
    Last edited: Aug 7, 2016
  6. Aug 8, 2016 #5
    So in reality, energy is just matter in another form? And there can be no energy without matter first?
     
  7. Aug 8, 2016 #6
    Read this again:

     
  8. Aug 8, 2016 #7
    Okay, now I get it.
     
  9. Aug 8, 2016 #8
    I have a question on this topic if it's not too much. I heard something about converting kinetic energy to matter and that this is done in the LHC. How can this be?
     
  10. Aug 8, 2016 #9

    jbriggs444

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    You start with particles with small rest masses but large kinetic energies relative to their combined center of mass. You end with a shower of particles with a larger total of the individual rest masses but smaller total of the kinetic energies.

    Energy is conserved. But "total rest mass of the individual particles" is not a conserved quantity.
     
  11. Aug 8, 2016 #10

    Chronos

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    Under inflationary cosmology the universe was initially composed entirely of energy [the inflaton field], which subsequently 'decayed' into matter. Under traditional big bang cosmolgy, the universe may have initially included some form of matter, however most, if not all, matter in the universe that emerged from inflation 'decayed' out of the inflaton field. Since matter and energy are equivalent under GR, the distinction is largely moot.
     
  12. Aug 8, 2016 #11

    Orodruin

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    I would not call this "entirely energy" or "pure energy" as it is a very common misconception that something called "pure energy" exists. The inflaton field is a field which also has energy as a property - just like the electromagnetic field and matter does.
     
  13. Aug 9, 2016 #12

    Chronos

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    Agreed, I'd being will to substitute the term devoid of matter for energy. I'm glad you raised the point because definiing matter and energy is not nearly as neat and clean as is typically imprinted upon laymen [IMO].
     
    Last edited: Aug 9, 2016
  14. Aug 9, 2016 #13
    What is this field made of? I am having a hard time finding out this answer. From what I get a field is something that has energy in every point of space but what exactly "holds it together" ? What makes it to be a structure and not just a bunch of points of energy?
     
  15. Aug 9, 2016 #14

    Orodruin

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    This is a moot question, it has no answer. A field is a basic part of the model, eg, the electromagnetic and gravitational fields. They are not "made of" something else, they are the basic enteties of the model.

    No, a field is something that has a value at every point. Then energy (or rather, energy density) can be associated to the field configuration, ie, what values the field takes.
     
  16. Aug 9, 2016 #15

    Chronos

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    Last edited: Aug 9, 2016
  17. Aug 9, 2016 #16
    I think I am missing something here. From what I understand, you sound as if fields have no description. Are you saying that fields are the fundamental building block and therefore cannot be divided further?
    Are they like an assumed axiom that cannot be proved but by assuming it exists, it answers some questions?

    P.S. Chronos, your link does not seem to work. Is it just me or it's broken ?
     
  18. Aug 9, 2016 #17

    Chronos

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    Link repaired. Just for clarification a field has potential energy at every point, it requires some kind of interaction for that potential to be realized.
     
  19. Aug 9, 2016 #18
    The link works OK for me, won't be able to read it til tomorrow though.
    edit:. Ah I see now that it had been updated.

    Yes I think it's fair to say that a lot of theories start from the proposition that if X is true then Y should be true, where Y is something tangeable that can be measured.
     
  20. Aug 9, 2016 #19

    mfb

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    Physics cannot prove anything. Physics makes models based on observations and compares the predictions of those models to more observations. The model of fields as fundamental concept works extremely well.
     
  21. Aug 10, 2016 #20
    Yes, my bad. Logic proves, science demonstrates. So was I right in saying that fields are similar to axioms ? They are assumed and because that assumption gives us results, we suppose that assumption is right?
     
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