Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Does Light Exist Outside Time

  1. Oct 15, 2012 #1
    In relativity, it says that faster you approach the speed of light, the more things slow down. Is this on a sensory level, or actually, physically slow down?

    I mean, if light were "outside" time, then it wouldn't truly move, would it. We couldn't say light had a speed because it does not have a time. Rather than actually physically slowing down, everything would seem to slow down, or so it seems. That the relativity is just that- how everything would appear relative to being on a thing going so fast. That you would be behind a thing and past it and if your consciousness had the "frame-per-rate" to comprehend what goes between one nanosecond and the other, that thing would appear to be totally still, as if it hasn't moved because what makes an appreciable movement between one nanosecond and the next?

    At the same time, going fast as the speed of light and consciously assessing things at that speed are two different things. Even if a human were to go that fast, they would not be able to conceive of the trip on a fluid moment to moment basis. It would appear as, throughout the trip, the video was being pieced together with photos ten minutes apart. Maybe hours, Maybe months.

    Do I have the right idea?
     
  2. jcsd
  3. Oct 15, 2012 #2
    Physics always seems to be normal in one's immediate vicinity. It is always the other guy who seems to be slow. There are videos on Youtube that show how things would look.
     
  4. Oct 17, 2012 #3

    Drakkith

    User Avatar

    Staff: Mentor

    I guess you would call it a "physical" slow down. It actuality the effect is because there is a difference between your own frame of reference and another. That difference being something like high velocity, acceleration, etc.

    Relativity depends, at least in part, on being able to observe from inertial frames of reference, which are non-accelerating in the sense that an accelerometer would not measure an acceleration. When we do transformations using math we can calculate what one frame of reference is doing compared to another. It turns out that light CANNOT have an inertial frame of reference. In an inertial frame of reference all laws of nature work the same, including the law that the speed of light is the same for all inertial observers. IE from any inertial frame light always travels at c. Well, you simply cannot have a frame of reference travel at c AND view other light as traveling at c. Per the math, no time would pass, so you could perform no measurements or observations, which I take to mean that it isn't possible for an observer to travel at c or to have a frame of reference traveling at c. It's important to realize that just because the math may lead to some result does NOT mean that it is true.

    We need to be able to verify that our math makes accurate predictions using the rules in your theory. If the results do not match up to observations, then your theory is wrong. However, if your theory says that something isn't possible, then we also cannot use the same laws to predict what would happen at the point that the theory says it's impossible!

    So the short version is that we cannot assign a frame of reference to light, and we cannot get an observer up to light speed, so we cannot claim that light does not experience time. It obviously travels, and at a finite speed, and the electric and magnetic fields obviously oscillate, so I don't know how one could claim that it doesn't experience time.
     
  5. Oct 17, 2012 #4
  6. Oct 17, 2012 #5

    Drakkith

    User Avatar

    Staff: Mentor

    That simply records different pulses of light at different points in the object and then puts all the pictures together in a movie. It has nothing to do with the thread.
    Imagine shining a flashlight at different points in a dark room, taking pictures, and then combining them all to see a movie of you moving a flashlight around a room.
     
  7. Oct 19, 2012 #6

    Chronos

    User Avatar
    Science Advisor
    Gold Member

    It is impossible to translate the rest frame of light into any other inertial reference frame using lorentz transforms, hence, the short answer is - it does not exist.
     
  8. Oct 19, 2012 #7
    I recall reading this short article some time ago:
    http://phys.org/news/2011-08-photons-view.html

    It explicitly says that from a photon's point of view it is instantly emitted and reabsorbed, even if it crosses the whole universe or goes from your monitor to your eye.

    Is this a mis-interpretation, just a populist dumbing down?
     
  9. Oct 19, 2012 #8

    phinds

    User Avatar
    Gold Member
    2016 Award

    This is trying to do EXACTLY what Chronos just pointed out you CAN'T do. Since light HAS no frame of reference, there IS no "photon's point of view".
     
  10. Oct 19, 2012 #9

    Drakkith

    User Avatar

    Staff: Mentor

    It's nonsense. If you really wanted to look at it, from the photons point of view it is never emitted, never absorbed, and never travels anywhere because it cannot experience time. Fortunately this weird implication is simply meaningless since we cannot translate the photons frame into another one. IE it cannot even have a resting frame of reference.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Does Light Exist Outside Time
  1. Light and Time! (Replies: 9)

Loading...