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Light is a type of matter

  1. May 31, 2009 #1
    My friend believe that light is a type of matter. He thinks that light is a matter because it can be sucked into the black hole. So, I've wondered this. Is light a type of matter, or is it just a wave. If it is a wave, how can it be sucked into the black hole. Is light effected by the gravity? How can light travels through vacuum. What is the differences between the sound wave and the light wave, apart from sound wave need medium to travel.
     
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  3. May 31, 2009 #2

    DaveC426913

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    Re: Light?

    Your friend is wrong.

    Light is energy. Energy is affected by gravity. Gravity does not suck things; what gravity does is distort space-time. Light, and all other forms of electromagnetic radiation, follows the curved paths made by distorted space-time.
     
  4. Jun 1, 2009 #3
    Re: Light?

    light would be affected even if it was a wave.
     
  5. Jun 1, 2009 #4
    Re: Light?

    even you and I behave as a wave and a particle , wave particle duality.
    not only is light affected by gravity , it creates a gravitational field of its own.
    light is energy just like "davec426913" said but light can be transformed into matter
    an electron positron pair , E=mc^2
     
    Last edited: Jun 1, 2009
  6. Jun 1, 2009 #5

    ZapperZ

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    Re: Light?

    Please start by reading an entry in our FAQ thread in the General Physics forum.

    Zz.
     
  7. Jun 1, 2009 #6
    Re: Light?

    Not to argue with you Dave but does gravity distort space-time or does mass and energy distort space-time and gravity is the affect of the distortion.
     
  8. Jun 1, 2009 #7

    Dale

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    Re: Light?

    The particles we call "matter" are fermions which obey the Pauli exclusion principle. Photons are bosons and do not obey the Pauli exclusion principle.
     
  9. Jun 1, 2009 #8

    QuantumPion

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    Re: Light?

    I don't think this is correct. Matter is anything that has mass. There are bosons that have mass, such as the W and Z bosons (as well as composite particles such as mesons and helium-4).
     
  10. Jun 1, 2009 #9

    DaveC426913

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    Re: Light?

    Yes. My bad. I was over-simplifying. Yours is worded better.
     
  11. Jun 1, 2009 #10

    Dale

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    Re: Light?

    I disagree. A pair of photons travelling in opposite directions has mass, but is not matter. A container of hot gas has more mass than an otherwise identical container of cold gas, but no more matter. Etc. I would not equate matter with mass.

    The usual kind of basic definition of matter is anything that has mass and takes up space. Fermions take up space because they obey the Pauli exclusion principle. Bosons do not obey it, so they don't take up space, so they are not matter. However, you are correct that the majority of the mass of ordinary matter is due to the massive gauge bosons that mediate the strong interaction.
     
    Last edited: Jun 1, 2009
  12. Jun 1, 2009 #11
    Re: Light?

    This is a physical and metaphysical point simultaneously. Photon reunites in itself light that has to do only with the sense of sight and therefore it is not physical but a mental sense. At the same time light is physical object because it must have a reflecting matter means.

    Another way photon reunites in itself, of inseparable form, matter and energy. In their interaction photon performs like matter and energy at the same time.
     
  13. Jun 1, 2009 #12

    QuantumPion

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    Re: Light?

    I may not be a particle physics expert (just a lowly engineer :smile: ) but I think there are several problems with your statement... :confused:
     
  14. Jun 1, 2009 #13

    DaveC426913

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    Re: Light?

    Of this I am not aware.

    Maybe so, but it does not invalidate the claim that anything with matter has mass.
     
  15. Jun 1, 2009 #14

    Hootenanny

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    Re: Light?

    But that was not QuantumPion's claim.
     
  16. Jun 1, 2009 #15

    Dale

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    Re: Light?

    All fermions have mass, so I agree with the claim that all matter has mass. As Hootenany mentioned, that is not what I was objecting to. I was rejecting the reverse claim that anything with mass is matter.
     
  17. Jun 2, 2009 #16

    QuantumPion

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    Re: Light?

    :confused:
     
  18. Jun 2, 2009 #17

    Hootenanny

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    Re: Light?

    There are two 'claims' being discussed here:
    1. Anything with mass is matter
    2. All matter is mass
    The first of which is yours, which is what DaleSpam (and I) disagree with. Can you not see the difference between the two statements?
     
  19. Jun 2, 2009 #18

    QuantumPion

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    Re: Light?

    Perhaps I should specify rest mass? I thought the term "relativistic mass" had fallen out of use due to such confusion.
     
  20. Jun 2, 2009 #19
    Re: Light?

    Above not correct is it? Then something has mass but not matter, what is it? Photon?
     
  21. Jun 2, 2009 #20

    Dale

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    Re: Light?

    A pair (or more) of photons, thermal energy, the Z and W gauge bosons, etc. all have mass but are not matter. Thermal energy is probably the most clear-cut example of something with mass but not matter.
     
  22. Jun 2, 2009 #21
    Re: Light?

    Why is everyone arguing so much about this? Both "matter" and "mass" have several definitions, not just one. For example, just look at their wikipedia pages

    http://en.wikipedia.org/wiki/Matter
    http://en.wikipedia.org/wiki/Mass

    Anyway, I define matter as anything that can be influenced by energy and I define mass as anything that has a gravitational field.

    Flame shields up! :eek:
     
  23. Jun 2, 2009 #22

    QuantumPion

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    Re: Light?

    I don't know where you are getting that two photons have mass, you'll have to elaborate on that.

    I don't know why you say W and Z bosons are not matter. They are heavy particles which are force carriers for the weak interaction. I suppose you could make some argument to say they aren't matter because they have a short lifetime, or cannot exist as a free particle or some such; but the same properties hold true to a lesser extent for a neutron so you'll have to elaborate.

    I don't think your notion that thermal energy itself has mass, and therefore not all mass is matter makes sense. There is no such thing as thermal energy except as a property OF matter. A high temperature gas may have more relativistic mass due to the molecules' kinetic energy, but you can't have thermal energy without the matter to begin with. Just because a particle's relativistic mass increases with energy doesn't mean that you can classify that increase in energy as mass on its own in the absence of matter.
     
  24. Jun 2, 2009 #23

    QuantumPion

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    Re: Light?

    I think the problem with this is that energy itself has a gravitational field, so basically you are saying that everything in the universe has mass (which might not be incorrect but its confusing). Similarly your definition of matter pretty much encompasses anything, as even empty space is influenced by energy.

    As for your wiki definition of matter, I disagree with it in this context. The wiki article defines matter as anything that has mass and volume. With this definition, quarks and electrons, as we currently understand them, would not be considered matter as they are elementary point particles with no volume. But as fermions, collections of these particles DO occupy volume.

    If you want to make the argument that this is the case, and that an individual quark or electron is not matter but bound quarks are, and thus some things which have mass are not matter, then I can see where you are coming from. But I still disagree because I find the definition inconsistent :smile: . I stick by my definition of matter = anything with non-zero (rest) mass.
     
    Last edited: Jun 2, 2009
  25. Jun 2, 2009 #24
    Re: Light?

    Did you scroll down or just read the first paragraph? The wiki definition gives 7 definitions of matter, including one for quarks and leptons.
     
  26. Jun 2, 2009 #25

    QuantumPion

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    Re: Light?

    I scrolled down AND read it. It discusses what quarks and leptons are, and further defines ordinary matter as "anything composed of quarks and leptons" but basically leaves open the question of whether the elementary particles themselves, or indeed anything with mass, is matter or not.
     
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