Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: NB27 on 07/01/2015 02:10:10
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From what I understand, time stops at the speed of light. If, hypothetically, someone was able to travel at the speed of light.... would they cease to age?
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From what I understand, time stops at the speed of light. If, hypothetically, someone was able to travel at the speed of light.... would they cease to age?
Welcome to the forum!
That's a common misconception. Since nothing can ever travel at the speed of light then it's meaningless to say that anything will age at a rate for which time stops.
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Since nothing can ever travel at the speed of light ....
What about photons? Aren't they at the speed of light?
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From what I understand, time stops at the speed of light. If, hypothetically, someone was able to travel at the speed of light.... would they cease to age?
Yes. Note that whilst PmbPhy correctly said that you can't actually travel at the speed of light, you can in theory travel at a speed that is arbitrarily close to the speed of light.
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This seems like another variation on the question: “Do photons experience time?” It usually elicits some strong feelings, but probably cannot be resolved beyond saying that we have no physical model that covers that scenario.
As John points out, “you can in theory travel at a speed that is arbitrarily close to the speed of light.” However, as it would require infinite energy to accelerate a massive object to “c”, and take “infinite time” to get there, arbitrarily close is still infinitely far away, so no meaningful comparison can be made.
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Actually Bill, there's an easy way to travel at the speed of light.
I kid ye not. It doesn't even take any energy.
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As far as I know, you would have infinite mass at the speed of light. Tell me whether God can make a stone so heavy that he cannot pick it up. Then I will tell you whether time stops at the speed of light.
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Actually Bill, there's an easy way to travel at the speed of light.
I kid ye not. It doesn't even take any energy.
Slow light down in a super cool medium?
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Actually Bill, there's an easy way to travel at the speed of light.
It can be argued that we are all travelling through spacetime at the speed of light, always.
Slow light down in a super cool medium?
Not if you have to travel in the same medium. [:)]
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The effect of time is to separate events. If time stopped, how would you know it?
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What about photons? Aren't they at the speed of light?
They travel at the speed of light but it can't be said that photons age. Aging is either a chemical or a biological process, neither of which can take place is a frame of reference that is traveling at the speed of light relative to any inertial frame of reference.
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They travel at the speed of light but it can't be said that photons age. Aging is either a chemical or a biological process, neither of which can take place is a frame of reference that is traveling at the speed of light relative to any inertial frame of reference.
I understand, and agree with, what you are saying here, Pete; but the nit-picker in me will not be stilled. You are assigning a frame of reference to a photon; can you do that? Are you distinguishing between a F of R and an inertial frame?
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You have to assume a frame of reference for the photon. This frame changes during interactions with other fields. It does not have constant attributes so a scalar proportionality needs to be applied as with Lorentz transforms for any other type of mass. This becomes most apparent at the event horizon of a black hole. If we do not consider the frame of reference of the photon then how can we describe the effects on light? Using only the wavelength and energy of the photon is not enough in my opinion. How does the field of a slowed photon behave? Is the interaction of light with matter also slowed down?
EDIT: For an observer moving at a significant fraction of the speed of light and with increased mass/energy see an x-ray as visible light? This is one to ponder.
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I understand, and agree with, what you are saying here, Pete; but the nit-picker in me will not be stilled. You are assigning a frame of reference to a photon; can you do that?
No. That's the problem.
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Aging is either a chemical or a biological process, neither of which can take place is a frame of reference that is traveling at the speed of light.....
Sorry Pete, still nit-picking. [:)]
you refer to a "frame of reference that is traveling at the speed of light". A photon is the only thing that can travel at the speed of light; so are you not assigning a F of R to a photon.
Actually, this is not just a case of nit-picking. Elsewhere, I have been involved in a thread in which I was arguing that we cannot assign a F of R to a photon, so I'm keen to be aware of anything that might seem to be a flaw in my reasoning.
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The effect of time is to separate events.
Each event must differ in some respect from every other event, so what you are saying is that time emerges from change.
If time stopped, how would you know it?
The acquisition and recognition of knowledge involves change, so if change stops (a prerequisite of time’s stopping) there would be no knowledge of anything.
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Just another note on this. The spectrum of the photon will be shifted for an observer traveling at a significant proportion of the speed of light. Those photons arriving coincident with a direction exactly perpendicular to the direction of travel should preserve their energy, wavelength and frequency. Photon approaching from in front will be blue shifted and those following will be red shifted. It should then follow that visible light that follows the traveler will now be in the infra-red range. X-rays may then near but not reach the visible range of the spectrum but ultra-violet light may now be visible. Approaching x-rays will shift into a range approaching the energy of cosmic rays. I have done no mathematics on this so do not know the exact shape of the spectrum in such a situation. It will vary around a 360 degree plane and with the angle of the approaching photon.
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Its Very Simple, just record a video of light travelling and play it, then forward to increase the speed of light and rewind to slow the speed of light.
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Its Very Simple, just record a video of light travelling and play it, then forward to increase the speed of light and rewind to slow the speed of light.
Hi KA, welcome.
How would you do that? As I understand it, the light would be visible to your camera only when the photons entered the lense, after which it would no longer be travelling.
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Its Very Simple, just record a video of light travelling and play it, then forward to increase the speed of light and rewind to slow the speed of light.
That doesn't really have anything to do with faster than light motion. It's also not possible to record a beam of light in that way. What you're doing is recording is the light off of an object which is standing still or moving at speeds less than c.
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Slow light down in a super cool medium?
Nope. It's even easier than that.
...This becomes most apparent at the event horizon of a black hole...
Close but no cigar. What's the coordinate speed of light at the black hole event horizon? And if you fall into a black hole from a hypothetical "infinite" distance, what's your speed alleged to be when you allegedly cross that event horizon?
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Slow light down in a super cool medium?
Nope. It's even easier than that.
...This becomes most apparent at the event horizon of a black hole...
Close but no cigar. What's the coordinate speed of light at the black hole event horizon? And if you fall into a black hole from a hypothetical "infinite" distance, what's your speed alleged to be when you allegedly cross that event horizon?
What you are saying is that falling into the event horizon of a black hole achieves superluminal speed with no involvement of energy. Right? You are really saying that superluminal speed is achieved before the event horizon. I have been down this path but there are severe problems with this approach.
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The complexities of interstellar/intergalactic travel is rarely illustrated in science fiction.
IN STAR WARS, HOW DO PEOPLE COMMUNICATE WITH OTHER PEOPLE AT DIFFERENT PARTS OF THE GALAXY IN REAL TIME????????????????????????????????
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The complexities of interstellar/intergalactic travel is rarely illustrated in science fiction.
IN STAR WARS, HOW DO PEOPLE COMMUNICATE WITH OTHER PEOPLE AT DIFFERENT PARTS OF THE GALAXY IN REAL TIME????????????????????????????????
Real-Time communication that far away is not possible in nature. That's merely sci-fi which doesn't adhere to the laws of nature.