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Topic: Can we see our face?????? (Read 1794 times) |
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checker
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Can we see our face??????
« on: Feb 19th, 2007, 9:10pm » |
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Our here I am posting the question of einstien whose answer I am searching for:
If we are traveling with the speed of light with a mirror in our hand......and then a beam of light stricks our face........then...Can we be able to see our face ??
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towr
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Re: Can we see our face??????
« Reply #1 on: Feb 20th, 2007, 12:37am » |
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Yes and no. In our frame of reference we can, light always travels at, well, speed of light, in our own frame of reference (all things moving at the same speed in the same direction). However, to outside observers, our time seems to stand still, so they would rightfully say we can't see ourselves, or move, or do anything.
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ThudnBlunder
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Re: Can we see our face??????
« Reply #2 on: Feb 20th, 2007, 1:25am » |
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on Feb 20th, 2007, 12:37am, towr wrote:| However, to outside observers, our time seems to stand still, so they would rightfully say we can't see ourselves, or move, or do anything. |
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While we are on the subject, I think even Madonna might agree it is really neat that from the point of view of a photon length telescopes to nothing in the direction of travel, as does time relative to a stationary observer. So for a 3D pulse of light there is no physical universe or time. Or answers such as '42' because there are no annoying little questions such as 'Why are we here?'.
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rmsgrey
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Re: Can we see our face??????
« Reply #3 on: Feb 21st, 2007, 8:34am » |
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Of course, at times light itself moves slower than the speed of light, which will have all sorts of weird effects...
As to the original question, at high enough speeds, either the oncoming beam of light will be blue-shifted into high-energy gamma, which will mostly pass straight through you, or the reflected light will be red-shifted into very long-wave radio, which will pass by a hand-held mirror without noticing it, so you're unlikely to see much...
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JiNbOtAk
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Re: Can we see our face??????
« Reply #4 on: Feb 21st, 2007, 4:49pm » |
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on Feb 21st, 2007, 8:34am, rmsgrey wrote:Of course, at times light itself moves slower than the speed of light, which will have all sorts of weird effects...
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I thought the speed of light is constant, and it stays constant regardless of medium, time, space, etc. ?
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ThudnBlunder
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Re: Can we see our face??????
« Reply #5 on: Feb 21st, 2007, 4:56pm » |
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on Feb 21st, 2007, 4:49pm, JiNbOtAk wrote:
I thought the speed of light is constant, and it stays constant regardless of medium, time, space, etc. ? |
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Nope, it is constant and equal to c in a vacuum. Through glass or water it is about 0.67c, IIRC.
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JiNbOtAk
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Re: Can we see our face??????
« Reply #6 on: Feb 21st, 2007, 5:18pm » |
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on Feb 21st, 2007, 4:56pm, THUDandBLUNDER wrote:
Nope, it is constant and equal to c in a vacuum. Through glass or water it is about 0.67c, IIRC.
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Ahh, yes. Sorry for the blunder. 
How about gravity ? Does gravity effect the speed of light, or just the path it travels ? Or is that just an illusion ?
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Icarus
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Re: Can we see our face??????
« Reply #7 on: Feb 21st, 2007, 5:57pm » |
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That depends on how you define things. According to Einstein's General Theory of Relativity, you can either consider spacetime to be flat (at least locally), in which case gravity is a force that acts on everything passing by, or you can consider spacetime to be curved by the presence of matter, in which case gravity is just an illusion caused by us expecting spacetime to be flat. I.e., light is just moving in a "straight line", but because the spacetime itself is curved, that straight line does not behave like we think it should. The discrepancy between the actual behavior of light (and other particles) and what we expect is what we think of as the force of gravity.
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Grimbal
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Re: Can we see our face??????
« Reply #8 on: Feb 22nd, 2007, 5:41am » |
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on Feb 21st, 2007, 8:34am, rmsgrey wrote:| Of course, at times light itself moves slower than the speed of light, which will have all sorts of weird effects... |
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Such as letting your eye focus on the reflection of your face.
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Random Lack of Squiggily Lines
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Re: Can we see our face??????
« Reply #9 on: Mar 10th, 2007, 9:34pm » |
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gravity should effect light, after all, black holes' gravity is so strong it can suck up light.
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Icarus
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Re: Can we see our face??????
« Reply #10 on: Mar 10th, 2007, 10:04pm » |
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Actually, according to Einstein, gravity doesn't affect light at all - nor does it affect matter. Instead it affects spacetime, bending it so that a "straight" path bends. A black hole bends spacetime so extremely that within its event horizon, straight lines are bent into closed circles that do not extend beyond that horizon.
Black holes do not suck up light. "Straight lines" starting outside the horizon bend in ways that mean they stay outside the horizon. Light is not directly influenced by the black hole. It simply follows a straight path. Because of the bending of spacetime, this path will always bend to go around the black hole. Light inside the black hole follows the paths inside that bend so as to never leave the black hole.
So light inside stays inside, light outside stays outside, but all because there is no straight path that crosses the event horizon.
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towr
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Re: Can we see our face??????
« Reply #11 on: Mar 11th, 2007, 8:42am » |
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on Mar 10th, 2007, 10:04pm, Icarus wrote:| Actually, according to Einstein, gravity doesn't affect light at all - nor does it affect matter. Instead it affects spacetime, bending it so that a "straight" path bends. |
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I don't think Einstein actually distinguishes which of the two cases is true. It depends on whether you prefer to look at space as Euclidean or non-Euclidean. Which is actually the case can't be distinguished by experiment.
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Icarus
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Re: Can we see our face??????
« Reply #12 on: Mar 11th, 2007, 11:28am » |
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More correctly, Einstein posits that essentially both are true - that is, both view points are equally capable of describing reality. The only difference is how you interpret the equations - not what the equations are.
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srn437
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Re: Can we see our face??????
« Reply #13 on: Sep 8th, 2007, 8:31pm » |
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When you move at the speed of light, your mass is real and imaginary, so is there anything to reflect? What if the same applies to the mirror? I'll try it after mastering telekinesis.
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towr
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Re: Can we see our face??????
« Reply #14 on: Sep 9th, 2007, 7:52am » |
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on Sep 8th, 2007, 8:31pm, srn347 wrote:| When you move at the speed of light, your mass is real and imaginary |
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That is true in as much that you can't move at the speed of light, and therefor your mass, aside from being real and imaginary, is also pink and invisible, has a strangely gooey texture, and tastes like electric sheep.
Particles with (rest)mass can't move at light speed. (To accelerate to light speed would take infinite energy and increase the mass infinitely)
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srn437
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Re: Can we see our face??????
« Reply #15 on: Sep 9th, 2007, 10:07am » |
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Does that mean I can or can't see my reflection?
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towr
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Re: Can we see our face??????
« Reply #16 on: Sep 9th, 2007, 10:48am » |
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on Sep 9th, 2007, 10:07am, srn347 wrote:| Does that mean I can or can't see my reflection? |
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Particles (objects) moving at the speed of light don't experience time; since it takes time for something to reflect, and to see, I'd say no.
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Grimbal
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Re: Can we see our face??????
« Reply #17 on: Sep 9th, 2007, 10:53am » |
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I would say no. Because if you travel at the speed of light, your own clock slows down to the point of stopping, which means you would have no time to actually experience anything. And anyway, the light wouldn't have the time to go to the mirror and back.
Assuming it were possible to move at the speed of light, you would only experience the time before you reach that speed and the time after you slow down a bit. The time where you travel at the speed of light will pass in zero of your own time.
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srn437
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Re: Can we see our face??????
« Reply #18 on: Sep 9th, 2007, 11:41am » |
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Also, objects slower than light never move at the speed of light or faster and objects faster than light never slow down to the speed of light or slower. So what if I was faster than light? Or what if I let go of the mirror?
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ima1trkpny
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Re: Can we see our face??????
« Reply #19 on: Sep 9th, 2007, 8:03pm » |
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on Sep 9th, 2007, 11:41am, srn347 wrote:| Also, objects slower than light never move at the speed of light or faster and objects faster than light never slow down to the speed of light or slower. So what if I was faster than light? Or what if I let go of the mirror? |
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It would be an interesting thing to play with if you could actually find a way to experiment... but the fun little thing about the speed of light is that matter doesn't want to travel that fast. Not sure if you have yet come across it, but as particles approach the speed of light, they gain mass so as to avoid going the speed of light.
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ThudnBlunder
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Re: Can we see our face??????
« Reply #20 on: Sep 9th, 2007, 8:27pm » |
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on Sep 9th, 2007, 8:03pm, ima1trkpny wrote:| ...they gain mass so as to avoid going the speed of light. |
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So if srn347's brain moves at the speed of light, as appears to be the case, can we conclude once and for all that it has zero mass?
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| « Last Edit: Sep 10th, 2007, 8:17am by ThudnBlunder » |
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srn437
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Re: Can we see our face??????
« Reply #21 on: Sep 9th, 2007, 8:30pm » |
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If thudingblunder moves up the evolutionary chain at the speed of light, does his brain become an ameoba in 1000 years?
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ima1trkpny
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Re: Can we see our face??????
« Reply #22 on: Sep 9th, 2007, 8:39pm » |
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on Sep 9th, 2007, 8:27pm, ThudanBlunder wrote:
So if srn347's brain moves at the speed of light, does this mean it has no mass?
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 Was trying to decide whether to answer that seriously or not for a few minutes... but so as not to confuse him I will speak the truth... ("I cannot tell a lie!") His brain would become infinitely massive... somehow I have a feeling he doesn't have this problem yet...
on Sep 9th, 2007, 8:30pm, srn347 wrote:| If thudingblunder moves up the evolutionary chain at the speed of light, does his brain become an ameoba in 1000 years? |
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And that would be regression darling... the opposite of evolving... but who knows... ameoba's have a strange elegance in their simplicity, it is feasable they may one day take over the world
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ThudnBlunder
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Re: Can we see our face??????
« Reply #23 on: Sep 9th, 2007, 8:43pm » |
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on Sep 9th, 2007, 8:39pm, ima1trkpny wrote:| His brain would become infinitely massive.. |
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Hence, by reductio ad copmpletely absurdum, its rest mass is precisely zero, as expected.
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| « Last Edit: Sep 10th, 2007, 8:18am by ThudnBlunder » |
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srn437
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Re: Can we see our face??????
« Reply #24 on: Sep 9th, 2007, 8:48pm » |
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Ameoba's take over the world?! Humans are at the top of the chain and we have telekinesis(which hasn't been unlocked yet). http://www.wingmakers.co.nz/Teleportation.html
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