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I Some questions regarding energy

  1. Mar 6, 2016 #1
    I need some expertise on the following claim:

    "Energy even we think that it can NOT be destroyed does not cumulate of its own to form matter. For our universe to function the way it is functioning right now, i.e. moving towards a heat death as if it started as a potential, energy should come together to form the matter. Energy by its nature dissipates not cumulates. To use the energy to create matter out of it, we need purposeful and conscious act so that the end result should be in the from of an energy that could converted into physical work and increasing the entropy when doing that so."

    Now, please note that I am not trying to start a discussion about religion or god/gods. I am simply asking for your expertise on the claims above.

    Isn't it true that all cosmological models we have thus far show that at the early stages of the Universe, there was no matter but only energy?
    Isn't it true that just recently scientists turned photons into matter?
     
  2. jcsd
  3. Mar 6, 2016 #2

    mfb

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    Are cosmic rays conscious? Because if they hit Earth, exactly that happens. And similar reactions happened in the early universe.
    Energy is not an object on its own. Particles can have energy. There are your particles - and collisions of high-energetic particles produce more particles.
    If you want to call 1970 recently...
     
  4. Mar 6, 2016 #3

    mathman

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    Pair production (gamma rays to positron electron pair) concept first proposed by Dirac in 1928. It was soon after observed.
     
  5. Mar 6, 2016 #4
    But aren't photons and cosmic rays particles? Photons are elementary particles and cosmic rays are high energy charged particles. Isn't that matter? I feel like I'm making a horrible mistake here.
     
  6. Mar 6, 2016 #5

    davenn

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    have a read of this wiki link :smile:

    https://en.wikipedia.org/wiki/Cosmic_ray

    see if that clears it up a bit

    Dave
     
  7. Mar 6, 2016 #6

    Dale

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    It depends on how you define the word "matter". But practically speaking it is a distinction without any importance. The point is that there is not any energy just floating around as pure energy by itself. Energy is always a property of something, be it a system or a particle or a field.

    So the idea in the quote is just baseless. There is no need for energy to come together to form matter, it already is a property of matter and fields.
     
  8. Mar 6, 2016 #7

    phinds

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    Photons are not particles in the classical physics sense. They are quantum objects that will exhibit wave characteristics if you measure for wave characteristics and particle characteristics if you measure for particle characteristics. Another way of saying that is that photons are excitations of the electromagnetic field when the field hits an object
     
  9. Mar 7, 2016 #8
    It did, thanks.

    But don't all cosmological models state that in the early stages of the Universe, there was no matter at all? How did the first matter appear?
     
  10. Mar 7, 2016 #9

    mfb

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    In every cosmological model there was matter as early as we have some idea what happened. Not in the current state, of course, because it was way too hot, but there was matter around. This statement is independent of a precise definition of "matter".
     
  11. Mar 7, 2016 #10
    What about models that attempt to go beyond the Big Bang? I know they are hypothetical for now but I'm curious from what state of things they propose the Big Bang "came from".
     
  12. Mar 7, 2016 #11

    mfb

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    It doesn't matter - all the energy is always in some fields or particles (or states where it doesn't make sense to distinguish between fields and particles).
     
  13. Mar 7, 2016 #12

    ZapperZ

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    This really shouldn't even be something within your radar right now (at least, not within this thread), considering that you still don't have a clear understanding of "energy" and "photons". You need to learn how to first walk before you attempt to do a 100-meter sprint.

    Zz.
     
  14. Mar 7, 2016 #13

    ogg

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    I learned a new word: cumulate. Energy is a property (or characteristic) of something (or some "thing"). Another way to put that is that energy is an abstraction. Most things around you have color. Some are red, some blue, etc. etc. So, claiming that flowers have color is true, but at the same time not quite true: red is a color but color doesn't mean red. Color is an abstraction - a way to unite separate things (red, orange, ...blue, violet, and more) and speak about their shared characteristics together. Similiarly, energy is an abstraction which is very useful because it is conserved: potential energy can be converted to kinetic energy and then back again, and we can frame this in terms of conservation of energy. I have zero idea what "starting as a potential" is supposed to mean. Jibberish. And the quoted text will only get you so far. I should also mention that a good way to look at the cosmological constant is that it is the energy density of empty space (vacuum energy). Since space is expanding, and the density is constant, energy is also increasing (on cosmological scales). It is not conserved, using this viewpoint.
     
  15. Mar 7, 2016 #14

    ogg

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    Also, if you think energy is more "intuitive" than entropy, you probably understand neither very well. Both are abstractions, and, while different, share many similarities (but not conservation). Most "advanced" physics speaks not about particles, but about fields. These fields pervade all space. If (most of) the energy of a field is localized, we'd call that a particle. Conversely, a particle is a localized field. For most of the math we use to work, we often require these fields to vanish at ∞ (meaning their cumulative energy approaches a constant value). Fields which do not disappear at ∞ pose a challenge to our understanding of how things work. [ie the vacuum energy density being constant is a problem, so other ways to address an accelerating expansion exist] {note: here the term "field" means a quantum mechanical field, not the fields of Classical Physics (electric field, gravitational field, etc.)}
     
  16. Mar 10, 2016 #15

    Dale

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    No. They state that the matter was much more similar to the stuff in the large hadron collider than to the stuff in your house.

    You may be confused by the term "radiation dominated" vs "matter dominated", but even in the radiation dominated early universe energy was associated with massless fields like photons, and not just free floating.
     
  17. Mar 10, 2016 #16
    Have we ever observed energy free floating in any instance? Do we know if it's even possible?
     
  18. Mar 10, 2016 #17

    Dale

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    No.

    Energy is not a thing, it is a description of a thing. Adjectives modify nouns, they don't float around on their own.

    You can have a suitcase, and you can have a heavy suitcase, but you can't have a heavy.
     
  19. Mar 10, 2016 #18
    On a lighter note, to explain the allegory you did use "heavy" independently. :wink:
     
  20. Mar 13, 2016 #19
    Could anyone give their take on this video?


    It appears to be in direct contradiction with what you guys have been saying.
     
  21. Mar 13, 2016 #20

    Dale

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    What? An Internet video is wrong? How could that possibly be given the rigorous peer review system used?
     
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