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Faster than a photon

  1. Dec 27, 2009 #1
    My first question on this forum..
    I always wondered, what if you could travel faster than a photon? How would it look like traveling? Would it look like a stand still image of where ever is was made? And how would you see the photon if you are faster than it? Doesn't make sense because its not reaching you, or I'm I missing something here?
     
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  3. Dec 27, 2009 #2

    HallsofIvy

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    Based on what fundamental theories?

    According to classical physics, It wouldn't look terribly different that traveling slower than photons. Photons from in front of you could still reach you- but but things would appear distorted- shifted to the side. Photons from behind you would not reach you but you wouldn't notice that; photon's from things off to the side slightly would appear to come from behind you and would "fill in" for the missing photons.

    If you are asking about relativity, however, you cannot go faster than the speed of light, so you cannot ask the question. You cannot deny part of relativity and then as "what would relativity say"!
     
    Last edited by a moderator: Dec 27, 2009
  4. Dec 27, 2009 #3
    Thanks HallsofIvy,
    Its kind complicated to understand everything you said, I never studied physics but I love it.
    Ok, another thing..
    What happens to photons that are traveling in an empty direction? will they vanish at certain distance?
     
  5. Dec 27, 2009 #4

    jtbell

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    If there is nothing for a photon to interact with, it keeps going and going.
     
  6. Dec 28, 2009 #5
    from what i read "a brief history of time" it says in theory time would go backwards if you make a round trip back 2 Earth (a U turn)... that implies after you've U turned you would see a reversed video tape of the history of the Earth? in very fast motion? :P
    the above assumes somehow the time stops for you in the view of people on Earth problem is ignored..
    of course there are huge problems in this problem :P
     
  7. Dec 28, 2009 #6
    what about background microwave radiation from big bang? isn't it red shifted some how? or am i missing something and it's interacting with something?
     
  8. Dec 28, 2009 #7

    HallsofIvy

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    I have also read "A Brief History of Time" and it says nothing of the sort.
     
  9. Dec 28, 2009 #8
    maybe i wasn't clear, the space ship going back in time idea is from "A Brief History of Time", the rest would be what i would predict
     
  10. Dec 28, 2009 #9

    ZapperZ

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    Maybe you should make an explicit quote out of that book to show us where you got this. Many of us have read the same book (and having physics degrees) and no such claim was made. Time may slowed down, yes, but not "go back".

    And in case you might have missed it as a new member, please re-read the https://www.physicsforums.com/showthread.php?t=5374" that you had agreed to.

    Zz.
     
    Last edited by a moderator: Apr 24, 2017
  11. Dec 28, 2009 #10
    Well, I thought about it and I think:
    If you travel along the photons, observe them and go faster than them then you would probably see a reverse video.
    But if you start with the oldest photon and go back toward the newer ones then you would see normal or fast forward video.

    Just another question,
    Is a photon made out of atoms just like another element?
     
  12. Dec 28, 2009 #11
    photon is not made from atoms. But you can say it as a fundamental particle for light (any electromagnetic waves).
    It consists of magnetic and electric fields (perpendicular to each other). Mass is zero for photon. These both fields behaves sinusoidally!
    For a picture of photons..you can find in any basic physics book..
     
  13. Dec 28, 2009 #12
    sorry about the missing qoute
    firstly i assumed everyone understood that in my response i assume faster then light is possible. since it was assumed in starting the topic...

    chapter 10 paragraph 12 of my version "A Brief History Of Time" By Stephen Hawking
    "If onewent slightly faster, one could even get back before the race and place a bet on it in the sure knowledge that
    one would win.
    "

    in the illustrated version there's a diagram of the space ship "U turning" (this is from memory i don't have the illustrated version with me)

    i know it's easy to miss a sentence, i only remember it because i remember the diagram from the illustrated version
     
    Last edited by a moderator: Apr 24, 2017
  14. Dec 28, 2009 #13

    ZapperZ

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    This is different than what you wrote earlier:

    This is what we are disputing.

    Secondly, the big "IF" should be emphasized regarding "faster than light", since so far, this is only purely mathematical and unphysical.

    Zz.
     
  15. Dec 28, 2009 #14
    it doesn't matter how big an IF it is, we assumed it in the question... "what if you could travel faster than a photon?" from the first post
    how is it different?
    if we assumed we can travel faster then light (as also assumed in the text) then the theory does work this way....( the theory in from the text whatever they're using)
     
    Last edited: Dec 28, 2009
  16. Dec 28, 2009 #15
    According to the Special Theory of Relativity, going faster than light is not possible, it would require an infinite amount of energy, although tachyons, etc are exceptions. Unfortunately, tachyons were never proven to actually exist, therefore, for now, we can say it is impossible to travel faster than the speed of light.
     
  17. Dec 28, 2009 #16

    ZapperZ

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    If we assume that all the laws of physics doesn't work.....

    Just because one can ask a question, doesn't mean it makes any sense, or if it is physical. There are many solutions to many problems, even in undergraduate physics, in which you end up with "extra" mathematical solutions that are unphysical.

    So far, I think you've been too caught up with this, i.e. the realm of the unphysical, without first understanding the realm of what we already understand (re: your claim that time goes backwards upon reversing travel). Understand the BASIC first before going out on the limb on something still speculative!

    Zz.
     
  18. Dec 28, 2009 #17
    Speculation is good, it can broaden your knowledge (although, it can also send it flying out there somewhere). I agree, though, venturing in the realm of the unphysical is good, but understand the one you're in first.
     
  19. Dec 28, 2009 #18

    ZapperZ

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    Speculation is "good" only when it is based on knowledge and not ignorance. As scientists, we "speculate" all the time because the nature of our jobs is to explore things that we still do not fully understand. However, speculations based on lack of understanding of the present-day knowledge is crackpottery waiting to happen. The latter is also not allowed, per our PF Rules.

    Zz.
     
  20. Dec 28, 2009 #19
    Exactly, you must have a base for speculation, although, not only scientists speculate upon that which we do not understand. As humans, our nature is to attempt to understand that which we do not yet understand.
     
  21. Dec 28, 2009 #20
    hmm... actually your right it was my mistake it should be in forward motion...

    i don't see a huge difference between this and Einstein's day dream of sitting on a beam of light...
     
  22. Dec 28, 2009 #21
    current does not imply it's right... anyone that thought the Earth was round a few thousand years ago would be considered a crackpot...
    if future humans look back, they'll most likely think we're blind to the 'actual' truth...
    i have just extended the idea from "a brief history of time", sure i made a careless mistake, when your ship's coming back you'll see photons head on, and the most recent happenings would be the latest ones so it's forward...
     
  23. Dec 28, 2009 #22
    That's right, current does not imply that it is correct. However, the term 'correct' is relative. Think about it this way: when someone formulates a valid unification theory, our Forces will be considered crackpottery, as well as your analogy 'anyone that thought the Earth was round a few thousand years ago would be considered a crackpot...' therefore, assume that what is current, is correct. For now... Things are always changing, and knowledge changes with it.
     
  24. Dec 28, 2009 #23

    HallsofIvy

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    Even that statement is not true. Any educated person, back as far as the ancient Greeks, knew that the earth was round. In fact, Eratosthenes calculated the radius and circumference of the earth about 2050 years ago.

     
  25. Dec 28, 2009 #24
    Remember, he said 'considered', also, the church dominated at that time, so they were considered crackpots, even if they weren't.
     
  26. Dec 28, 2009 #25
    ok maybe a better example would be the Earth revolving around the Sun.... this example should be clearer
     
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