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Thread: What is energy?

  1. #1 What is energy? 
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    Hi,

    Here's a quote: "Current thinking holds that right after the Big Bang that formed the universe, only energy existed, but as the universe cooled, matter and antimatter were produced in equal parts."

    What is meant here by energy? I know what's a particle but can't understand what's energy.
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  2. #2  
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    Try thinking of it as space itself. I know that sounds er "novel", but when you get down and dirty with the fundamental physics, that's where you hit the buffers.
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  3. #3  
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    I actually have a hard time understanding what is meant by the quotation, even after looking at some of the many sources for the quotation. It seems an over-simplification that borders on being false.

    At best, it means that there was a period in the history of the universe where all that happened in the universe were exchanges of energy between different fields that we today identify but that are not associated with what we commonly call matter and anti-matter. So there might have been what we consider particles in some sense, but no electrons, no protons, no neutrons, no quarks, and none of a handful of other particles.

    At some point, the energy flowing back and forth among these fields dropped enough such that their interactions reliably produced what we think of as matter and anti-matter particles that lasted a long time. Eventually, there ended up being way more matter than anti-matter, for some unknown reason.

    It could be that they were produced in equal amounts or maybe there is some unknown reason why the fields produce more matter than anti-matter as they lose energy.

    This seems to be the case whether or not there was a beginning to the universe. That is, even if there is some physical reason to extend the history of the universe back indefinitely, it seems a solid inference that the universe was much smaller in the past, that it was so (relatively) compacted that there was a lot of energy in every place in the universe, and that the energy was so high that the interactions between fields at that time would not support the (long) existence of certain particles that are common today.
    Quote Originally Posted by Farsight View Post
    Try thinking of it as space itself. I know that sounds er "novel", but when you get down and dirty with the fundamental physics, that's where you hit the buffers.
    This is indeed novel, you will not find any physicists proposing this idea. redhalls, please be warned that Farsight makes a number of grand claims about physics that are not aligned with contemporary physics, even though he claims that they are what certain historical figures "really meant".
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  4. #4  
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    Hmmmm, how much energy does the vacuum have?
    1) None
    2) lots
    3) an infinite amount
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  5. #5  
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    What is meant here by energy? I know what's a particle but can't understand what's energy.
    Think of it as lots of photons.
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  6. #6  
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    PhysBang that was really good. Thanks
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  7. #7  
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    Was it? Then perhaps you can explain it to me? What is meant here by energy?
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  8. #8  
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    Quote Originally Posted by Farsight View Post
    Was it? Then perhaps you can explain it to me? What is meant here by energy?
    I think that trying to explain it to you would just lead to more mistakes that would not stain your character.
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  9. #9  
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    Quote Originally Posted by redhalls View Post
    Hi,

    Here's a quote: "Current thinking holds that right after the Big Bang that formed the universe, only energy existed, but as the universe cooled, matter and antimatter were produced in equal parts."

    What is meant here by energy? I know what's a particle but can't understand what's energy.
    It's not meaningful to say "only energy existed" since there is no physical entity which one can call "energy." Energy is more of a bookkeeping system than anything else.

    Energy exists in various forms, the sum of which is a constant of motion. For example; moving body has energy by virtue of its speed, v. That form is called kinetic energy. A body can also have energy by virtue of its position in space. That form is called potential energy. A body can have internal structure and in that structure it may have charged particles or compressed springs, etc. All those forms contribute to the inertia of the body and it's proper/rest energy. When all these forms are added you get a number that remains constant regardless of how the system changes.

    Iím not sure of the form it took during the quantum error. They think that there was an abundance of black holes and wormholes then. During the hadron era it took the form of rest energy and kinetic energy of all the particles that existed at that time plus gravitational energy (Whoever said that was leaving out the fact that the total energy of the universe was zero though). During this era the universe contained highly relativistic plasma of elementary particles such as electrons, gluons quarks, muons, taus, W and Z bosons, neutrinos and gravitons. The number of baryons and antibaryons were equal.
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