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Mass Question

  1. Mar 7, 2007 #1
    Is every bit of information (anything) in the Universe have mass?

    Also, light has to have mass because it is affected by gravity, correct?

    Last question, What is "space", not just outer-space but also the space we "live" in, made of? Is it filled with an infinite(or really big amount) amount of atoms?
    So, if this where true you could say that the Universe is just filled with an infinite (or really big amount) amount of atoms that make up everything...

    Sorry, I really like Physics but just have so many questions.
  2. jcsd
  3. Mar 7, 2007 #2
    The universe is made of both mass and energy. Light is made up of a particles called photons. Photons are massless.

    Other people can answer your other questions
  4. Mar 7, 2007 #3
    But if mass is affected by gravity, then it has to have mass. Light bends millions of miles away from the source.
  5. Mar 7, 2007 #4
    When it is said that "light has no mass" it is meant that the proper mass (aka "rest mass") of photons is zero. However the photon does have a non-zero inertial mass (aka "relativistic mass") and that is the mass that is affected by gravity.

  6. Mar 7, 2007 #5


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    Light is affected by space-time, space-time is affected by gravity, and gravity is created by mass, energy and pressure.
  7. Mar 7, 2007 #6
    Curious wording. Actually, there have been attempts to link the information content of the universe (in a Shannon's kind of sense) to the unexplained "dark energy".
  8. Mar 8, 2007 #7
    You forgot momentum too. That's why the tensor is called the stress-energy-momentum tensor.

  9. Mar 8, 2007 #8
    Throughout scientific history, force and matter were the underlying concepts in all endeavors to understand nature. Much effort has been directed to reducing the apparent complexity of the physical world to these fundamental perceptions. This idea was expressed even in the work of the Atomist, Democritus, 23 centuries ago:

    "By convention sweet is sweet, hot is hot, color is color...
    But in reality, only the atoms and the void are real"

    From what we know today, perhaps the world is even less substantive

    Maybe only the void is real.

  10. Mar 8, 2007 #9


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    Yes, I did forget momentum too.

    Thanks, PMB.
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