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Energy and matter Is that all that fills our universe?

  1. Jan 29, 2007 #1
    This question is just out of curiosity, but have you ever wondered if there exist other essential components besides energy and matter?
     
  2. jcsd
  3. Jan 29, 2007 #2
    None of the observations we make fail to be explained by mass-energy, except for possibly conciousness.
     
  4. Jan 30, 2007 #3

    berkeman

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    Staff: Mentor

    What third leg do you propose?
     
  5. Jan 30, 2007 #4
    Well, for example, what makes E=mc^2 possible? What makes energy so unified with mass? As well as were does the tide turn, when do you know that mass isn't mass and is now energy and what connects this notion? This is the true nature of my question, do you believe a "third leg" exists? One that bridges energy and mass?
     
    Last edited: Jan 30, 2007
  6. Jan 30, 2007 #5
    If a photon (a quanta of light) has enough energy, it can undergo pair production and form an electron and one positron for example. This has clearly been demonstrated in a bubble chamber. a lot of the things that needs to be conserved in this reaction is conserved. However, it is clear that mass is not. One way of explaining it is to say that the conservation of mass and conservation of energy is one and the same conservation law, that is, conservation of mass-energy. The formula [itex]E = mc^2[/itex] is used in this situation.

    http://teachers.web.cern.ch/teachers/archiv/HST2000/teaching/resource/bubble/bubble.htm
    http://rkb.home.cern.ch/rkb/PH14pp/node17.html

    Light and Matter has a number of textbooks available that deals with some of this information about conservation of mass-energy.
     
  7. Jan 30, 2007 #6
    So, what your saying is that what energy and mass have in common is the conservation law, which is true for both cases, and is therefore what unites them? I see... well alright, the conservation law makes it madatory for energy and mass to be conserved, I understand that but what makes it possible, what makes the transition possible? (Moridin: thanks for posting the websites, I found the cern page most enlightening :) )
     
  8. Jan 30, 2007 #7
    Is there a transition at all?

    It follows from the special theory of relativity that mass and energy are both but different manifestations of the same thing. The mass and energy is in fact equivalent, according to the formula mentioned above. This was demonstrated by Cockcroft and Walton in 1932, experimentally.

    Sure, anyone can say that mass and energy is the same thing, but that alone is hardly enough to understand the entire concept.

    Every conservation law comes from an underlying symmetry. For the conservation of energy, that symmetry is time symmetry, meaning that as time goes by, the universe doesn't change the way it works.
     
  9. Jan 30, 2007 #8
    Could you explain the last statement in more detail?
     
  10. Jan 30, 2007 #9
    That is actually Noether's Theorem.

    The orbit of the earth is elliptical, although only 1.7% from a perfect circle1. A circle is very symmetric, isn't it? As a result, the distance between the sun and earth is conserved, provided that the orbit is perfectly circular. Every conservation law comes from an underlying symmetry.

    1 Ben Crowell Conceptual Physics page 7
     
  11. Jan 30, 2007 #10
    Moridin, thank you for posting the book site.
     
  12. Jan 30, 2007 #11
    I would recommend opening up an undergraduate, introductory calculus-based physics text and start working through it. This is the only way you will really begin to understand the physical, non-sentient universe.

    The concepts of mass and energy can be better understood through the elegant relationship of experiment and mathematics.

    Although, perhaps my perception is distorted.

    - cP
     
  13. Jan 30, 2007 #12
    Im am currently trying to attain my major in chemistry, but I still haven't taken my required physics courses and, although I am taking calculus, currently I only have a high school level understanding of these concepts.
     
  14. Jan 30, 2007 #13
    So in short, symmetry is what defines the conservation laws which in part ties together energy and matter by defining each as conserved. Thank you everyone for you time.
     
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