Is it possible to go faster than light?

How does science work? And what's all this about quantum mechanics?

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Hobbes' Choice
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Re: Is it possible to go faster than light?

Post by Hobbes' Choice » Tue Nov 15, 2016 10:59 am

Philosophy Explorer wrote:
Hobbes' Choice wrote:
Philosophy Explorer wrote:My position is it is possible. Google wormhole and read what Einstein and Posen have theorized.

Einstein has been right so often (his latest triumph, gravitational waves, has been proven about a year ago). It remains for someone to discover wormholes.

PhilX
A human cannot stay a human in a wormwhole, even if there are such things.

So no you cannot travel faster than light.
What do you expect to happen with a human in a wormhole (depending on what type of wormhole?)

PhilX
Since the human body relies on the usually understood norms of mundane physics, such as all your molecules staying in one place, when the terrestrial norms no longer exist, neither does a human body.

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Greta
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Re: Is it possible to go faster than light?

Post by Greta » Wed Nov 16, 2016 12:40 pm

surreptitious57 wrote:
Greta wrote:
Maybe light cannot travel forever in space just as sound cannot travel forever in an atmosphere
Photons in vacuum travel at one speed as they have zero rest mass and in space that is forever
To quote from an answer to the Quora question, "Why does a light photon never degrade or change?":
Light degrades as it travels through space when it encounters objects such as dust but the photons don’t degrade because a photon is what can be extracted out of light at the observation point. If a single photon is transmitted over pure empty space it either arrives or misses the target but conservation of energy does not allow it to degrade.

Unrelated to the above photons are red-shifted in the expanding universe thus over large distances we can argue that they are degraded severely, sometime to the point of disappearing completely if sent beyond the cosmic horizon.

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Noax
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Re: Is it possible to go faster than light?

Post by Noax » Wed Nov 16, 2016 2:11 pm

Greta wrote:To quote from an answer to the Quora question, "Why does a light photon never degrade or change?":
I'd like to comment a bit on the perspective of the answer you quoted :
"Unrelated to the above photons are red-shifted in the expanding universe thus over large distances we can argue that they are degraded severely, sometime to the point of disappearing completely if sent beyond the cosmic horizon."
This is not degradation. The photon does not become red shifted. It retains its original frequency (energy) all the way. We might see it red shifted because we're observing in a different inertial reference frame, but that's not a change to the photon. In our frame, that photon was that lower frequency from the moment it was emitted. I could observe the light source from a meter away and get the same red shift.

And photons don't disappear over a horizon. Some just never hit anything. Light sources disappear over the cosmic horizon of some target for the light, but those sources are not light. This is due not to the expansion of space, but to the acceleration of the expansion of space. If space expanded at a steady pace, all photons would eventually reach any location along its path, and all stars would theoretically be eventually visible, even if red shifted to frequencies we have not even yet named.

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Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Wed Nov 16, 2016 2:19 pm

Noax wrote:
Greta wrote:To quote from an answer to the Quora question, "Why does a light photon never degrade or change?":
I'd like to comment a bit on the perspective of the answer you quoted :
"Unrelated to the above photons are red-shifted in the expanding universe thus over large distances we can argue that they are degraded severely, sometime to the point of disappearing completely if sent beyond the cosmic horizon."
This is not degradation. The photon does not become red shifted. It retains its original frequency (energy) all the way. We might see it red shifted because we're observing in a different inertial reference frame, but that's not a change to the photon. In our frame, that photon was that lower frequency from the moment it was emitted. I could observe the light source from a meter away and get the same red shift.

And photons don't disappear over a horizon. Some just never hit anything. Light sources disappear over the cosmic horizon of some target for the light, but those sources are not light. This is due not to the expansion of space, but to the acceleration of the expansion of space. If space expanded at a steady pace, all photons would eventually reach any location along its path, and all stars would theoretically be eventually visible, even if red shifted to frequencies we have not even yet named.
I and Einstein would disagree with you because our frame of reference is our (individual) reality and no frame of reference is preferable over another.

PhilX

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Re: Is it possible to go faster than light?

Post by Noax » Wed Nov 16, 2016 3:01 pm

Philosophy Explorer wrote: I and Einstein would disagree with you because our frame of reference is our (individual) reality and no frame of reference is preferable over another.
How nice that Einstein sides with you. Did I anywhere in that post indicate a preferred frame?

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Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Wed Nov 16, 2016 3:07 pm

Noax wrote:
Philosophy Explorer wrote: I and Einstein would disagree with you because our frame of reference is our (individual) reality and no frame of reference is preferable over another.
How nice that Einstein sides with you. Did I anywhere in that post indicate a preferred frame?
"We might see it red shifted because we're observing in a different inertial reference frame, but that's not a change to the photon."

It is a change to the proton with respect to the frame of reference.

PhilX

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Re: Is it possible to go faster than light?

Post by Noax » Wed Nov 16, 2016 3:55 pm

Philosophy Explorer wrote:
Noax wrote:
Philosophy Explorer wrote: I and Einstein would disagree with you because our frame of reference is our (individual) reality and no frame of reference is preferable over another.
How nice that Einstein sides with you. Did I anywhere in that post indicate a preferred frame?
"We might see it red shifted because we're observing in a different inertial reference frame, but that's not a change to the photon."

It is a change to the proton with respect to the frame of reference.

PhilX
How is that a statement of a preferred frame, since that was your (and Einstein's) point?

Yes, the frequency/energy/color of a photon is frame dependent, making that property a relation with the frame. A photon does not have an actual frequency that is the true one, and which might degrade over distance, as the Quora-answer quote sort of suggested.

Same thing with a rock which has frame dependent velocity, energy, color, and even mass. Does the rock change, or just the measurements of it from various observations in different frames? Rocks DO have an actual mass and a preferred frame (the one in which it is at rest), but that's just the frame of the rock, not a frame that is meaningful or preferential to the rest of the universe. Photons do not have an inertial frame of their own.

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Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Wed Nov 16, 2016 4:02 pm

Noax wrote:
Philosophy Explorer wrote:
Noax wrote:How nice that Einstein sides with you. Did I anywhere in that post indicate a preferred frame?
"We might see it red shifted because we're observing in a different inertial reference frame, but that's not a change to the photon."

It is a change to the proton with respect to the frame of reference.

PhilX
How is that a statement of a preferred frame, since that was your (and Einstein's) point?

Yes, the frequency/energy/color of a photon is frame dependent, making that property a relation with the frame. A photon does not have an actual frequency that is the true one, and which might degrade over distance, as the Quora-answer quote sort of suggested.

Same thing with a rock which has frame dependent velocity, energy, color, and even mass. Does the rock change, or just the measurements of it from various observations in different frames? Rocks DO have an actual mass and a preferred frame (the one in which it is at rest), but that's just the frame of the rock, not a frame that is meaningful or preferential to the rest of the universe. Photons do not have an inertial frame of their own.
Not what I said. What I'm saying with that particular example is that it shows the photon has undergone a change by being redshifted while you're saying it hasn't undergone a change. Clear now?

PhilX

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Noax
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Re: Is it possible to go faster than light?

Post by Noax » Wed Nov 16, 2016 4:58 pm

Philosophy Explorer wrote:Not what I said. What I'm saying with that particular example is that it shows the photon has undergone a change by being redshifted while you're saying it hasn't undergone a change. Clear now?
It hasn't changed. The perspective chosen is different is all. My car doesn't change its color of lights just because I choose to look at it from the other side. Likewise, a photon does not red shift as it travels. It has no original or preferred wavelength.

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Re: Is it possible to go faster than light?

Post by Philosophy Explorer » Wed Nov 16, 2016 5:19 pm

Noax wrote:
Philosophy Explorer wrote:Not what I said. What I'm saying with that particular example is that it shows the photon has undergone a change by being redshifted while you're saying it hasn't undergone a change. Clear now?
It hasn't changed. The perspective chosen is different is all. My car doesn't change its color of lights just because I choose to look at it from the other side. Likewise, a photon does not red shift as it travels. It has no original or preferred wavelength.
Again the frame of reference makes the difference = change.

PhilX

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Re: Is it possible to go faster than light?

Post by Terrapin Station » Wed Nov 16, 2016 5:23 pm

Is it possible to go faster than light?

Not by riding a tricycle. Believe me, I've tried.

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Re: Is it possible to go faster than light?

Post by thedoc » Wed Nov 16, 2016 10:53 pm

Terrapin Station wrote:Is it possible to go faster than light?

Not by riding a tricycle. Believe me, I've tried.
Try metal wheels, my grandson was telling me about people sledding down a hill in the snow and an older couple showed up with a sled that had metal runners. They went a lot faster than everyone else.

Failing that, try a bicycle, they are faster that tricycles. Motorcycles are even faster. Till you hit something, than none of them will move.

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Re: Is it possible to go faster than light?

Post by Greta » Thu Nov 17, 2016 4:20 am

Noax wrote:And photons don't disappear over a horizon. Some just never hit anything.
All photons must at least encounter countless bits of dust, molecules and stray EM. Each encounter will draw energy from the photon. They must degrade over time, like everything else, even if that time period is a very long one.

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Noax
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Re: Is it possible to go faster than light?

Post by Noax » Thu Nov 17, 2016 5:10 am

Greta wrote:
Noax wrote:And photons don't disappear over a horizon. Some just never hit anything.
All photons must at least encounter countless bits of dust, molecules and stray EM. Each encounter will draw energy from the photon. They must degrade over time, like everything else, even if that time period is a very long one.
You contradict the answer you quoted earlier: "If a single photon is transmitted over pure empty space it either arrives or misses the target but conservation of energy does not allow it to degrade."

That quote is correct about this. The photon hits the obstruction or doesn't. There is no degradation.

If the density of obstruction was high enough, we'd only be able to see so far. But we can see all the way to the edge of the universe where it goes opaque. That density of obstructions only grows thinner over time. Some photons will never hit anything. Some photons emitted from some finite distance straight in the direction of our solar system will never get this far, even given infinite time. That's the cosmic horizon referenced in the other half of the part you quoted. Under constant expansion, it would, but not under accelerated expansion.

I imagine most photons hit some obstruction almost immediately, but if they manage one light second, their probability of never hitting anything is pretty good. I say this as someone who lives in the rural backwoods of a galaxy. Most of our galactic light probably comes from the core, and effectively none of that light reaches us, so my statement above is probably BS. It also means that if you are in a more typical star like one near the core, you cannot see other galaxies, and would have a lot harder time working out a description of the evolution of our universe. They'd not know about Hubble's constant. So I amend my statement to say a photon that manages to leave the galaxy is likely to never hit anything.

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Re: Is it possible to go faster than light?

Post by Greta » Thu Nov 17, 2016 6:46 am

Noax wrote:If the density of obstruction was high enough, we'd only be able to see so far. But we can see all the way to the edge of the universe where it goes opaque. That density of obstructions only grows thinner over time. Some photons will never hit anything. Some photons emitted from some finite distance straight in the direction of our solar system will never get this far, even given infinite time. That's the cosmic horizon referenced in the other half of the part you quoted. Under constant expansion, it would, but not under accelerated expansion.

I imagine most photons hit some obstruction almost immediately, but if they manage one light second, their probability of never hitting anything is pretty good. I say this as someone who lives in the rural backwoods of a galaxy. Most of our galactic light probably comes from the core, and effectively none of that light reaches us, so my statement above is probably BS. It also means that if you are in a more typical star like one near the core, you cannot see other galaxies, and would have a lot harder time working out a description of the evolution of our universe. They'd not know about Hubble's constant. So I amend my statement to say a photon that manages to leave the galaxy is likely to never hit anything.
How does the fact that light from the Sag A* area doesn't make it to us contradict your comment about light in intergalactic space. I expect that if a photon made it to intergalactic space - and most of that would come from stars around the galaxy's periphery - then maybe it might not ever encounter something, although I believe that over extremely long time periods (ie. even longer than the Stelliferous Era) it would lose heat and redshift ever more until it dissipated entirely.

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