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A Universe without Light?

  1. Apr 19, 2008 #1

    mvx

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    Hello.
    I'm so glad I found this great forum.
    I was googling some info about light for a school project, and I found this great place, which I think is perfect for what I'm looking for.

    You see.. I have to make this school project about light in general, and at the end I have to answer a rather philosophical question: "What would the Universe be (look) like if there was no light?"

    I did some research myself, but I couldn't come up with anything good.. I also talked to some friends that are good at physics, but some of them say the Universe wouldn't exist at all, others say it would simply be extremly different.

    What do you think?

    Thanks :)
     
  2. jcsd
  3. Apr 19, 2008 #2

    Redbelly98

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    Well, maybe this can get you started.

    Back in the 1800's, it was discovered that light is a necessary consequence of the laws that explain basic electricity and magnetism. Not having light would mean we also don't have electricity, electric charges, etc.

    Since charged particles are the basic building blocks of atoms, NOT having them and still having anything that remotely resembles our universe is hard to imagine.
     
  4. Apr 19, 2008 #3

    Danger

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    Something should be clarified here, since people use different terminology sometimes. By 'light' do you mean the entire electromagnetic spectrum, or just the part that's visible to humans?
     
  5. Apr 19, 2008 #4

    mvx

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    the entire EM spectrum.

    Btw, here's what I have so far:

    If we had no light, then we wouldn't have any EM radiation generator.
    Thermal radiation is how objects cool down by producing EM radiations. Thus in our Universe without light, we wouldn't have the Thermal Radiation phenomenon.

    Thus objects would have to cool down in different ways. What would happen if matter would have to cool down in other ways, than by producing EM radiations?

    (Someone suggested that matter would never cool down, and become plasma but that is wrong, 'cause the energy is conserved in the Universe at all times, so a constant heating is impossible, right? )

    What consequences would have the absence of Thermal Radiation?
    and how can I take it further from here?
     
    Last edited: Apr 19, 2008
  6. Apr 19, 2008 #5

    nicksauce

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    Well if there were no photons, there would presumably no EM force, as it is carried by photons. Without the EM force there would presumably be no atoms or molecules, so there would be no 'objects' to cool down.
     
  7. Apr 19, 2008 #6

    mvx

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    omg omg omg that is so awesome, nicksauce!!
    thank you very very much.
    I did some research and you are right!

    so:

    no light => no EM radiation => no photons => no EM Force => no electrons around the nucleus.

    Now, what would happen to matter in this case? Electrons would float around free, while the nucleus would bind together? Can nucleus bind to each other? Is this the case of neutron stars, etc? ( en.wikipedia.org/wiki/Neutron_star )

    If nucleus could bind to each other, we would end up with really really dense matter.. like with a spoon weighting 10000000000 kilos (because we won't win so much space because of the electron cloud anymore, right?)
     
  8. Apr 19, 2008 #7

    Nabeshin

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    I think under the current standard model the strong nuclear force is carried by a gluon? So I think that would still be there. As for creating really dense matter... Well, you need extreme pressures to do that. It's not going to happen just because there are free floating ions lying around. The way I see it, you enter a universe governed by only three laws instead of four: Gravity, and the strong & weak nuclear forces.
     
  9. Apr 19, 2008 #8

    epenguin

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    Dark.
     
  10. Apr 19, 2008 #9

    dst

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    Two of which are primarily attractive forces.

    Assuming big-bang conditions, everything would eventually crunch back or otherwise. There isn't a hope in hell of atoms existing so likewise, such a question is essentially meaningless, it comes down to asking "what would happen if we removed all possible ways to observe the universe?".
     
  11. Apr 19, 2008 #10
    :rofl:
     
  12. Apr 19, 2008 #11
    Light has to exist, because interstellar objects, to balance overflow of energy, have to give off energy into vacuum, and EM waves are the only types of energy (I think?) that can be released into vacuum.
     
  13. Apr 19, 2008 #12

    Nabeshin

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    Stars can give off other forms of energy. One thing that instantly comes to mind is neutrinos, which I don't believe are electromagnetic in nature (correct me if that's wrong). That being said, a star that exists by solely emitting neutrinos... well that wouldn't be anything like a star we have, I don't think!
     
  14. Apr 19, 2008 #13

    dst

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    Oh and another thing;

    Technically energy IS the electromagnetic spectrum so the question may be rephrased - what would an energyless universe look like?
     
  15. Apr 19, 2008 #14

    Redbelly98

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    Well, electromagnetism is just one of several forms of energy. Without that, we still have energy from gravity, strong and weak nuclear interactions, and (possibly) dark energy.

    Only particles without any electric charge could exist. Neutrinos for example. But not neutrons, since they are composed of charged quarks.
     
  16. Apr 19, 2008 #15
    What universe? I can't see it...
     
  17. Apr 19, 2008 #16

    DaveC426913

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    Intestingly, in the universe's early childhood it was completely opaque; it was too hot for photons to penetrate.
     
  18. Apr 19, 2008 #17
    I always got pissed when I saw Bing Bang illustrations in science textbooks.
    It was just black.
    And those dumbasses don't even know.
     
  19. Apr 21, 2008 #18

    Danger

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    In a way, the original question is irrelevant. Without electromagnetism, life in any form that we can imagine couldn't exist; no observation of that universe, therefore, would be possible.
     
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