Is it possible to go faster than light?

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

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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 2:08 pm

Greta wrote: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.
Not sure what you're asking. It doesn't contradict. There's schmutz (mostly remnants of exploded stars) between us and Sgr A and almost all visible light hits something before getting to us. Really long wavelengths might make it through, so the imaging that has been done was via these super-IR wavelengths.
Said schmutz is far less prevalent looking outward, so there seems to be no limit to our sight distance.
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.
I'm saying that the physicists do not corroborate that belief. Red shift a difference between the frame of the observer and the frame of the emitting object, not a change to the photon.
If you observe a photon that originated from 10BLY away in the same frame as the object that emitted it, it would have the same frequency/energy as if you were there and had observed the thing shortly after it was emitted.
Similarly, you could be near the emitting object but choose to observe in the frame of our solar system now, and the photon would be fully red shifted.

If red shift was due to dissipation over distance, even light from Andromeda would be red shifted, not blue shifted. Is it picking up energy along the way? The blue shift is because we're moving toward Andromeda, a positive difference in frames instead of the usual negative one.

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

Post by Greta » Thu Nov 17, 2016 11:18 pm

Noax wrote:
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.
I'm saying that the physicists do not corroborate that belief.
http://futurism.com/science-explained-l ... -ever-die/

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

Post by Noax » Fri Nov 18, 2016 2:33 am

Interesting. Is this article quoting accepted science? I have not yet looked through the source article in the Physics Review Letters.

The article (discussing research done by Julian Heeck) hinges on photons having rest mass, and admits that photons cannot rest, but later contradicts itself. If something has mass, then moving it at light speed (impossible for anything with rest mass to move at that speed), its mass would become infinite (plug speed C into the Lorentz transformation).
The article mentions an upper limit to the mass (which you'd think would be dependent of the energy of the photon, but Heeck is specifically using microwave photons as his example). It gets less plausible after that. Time dilation is brought in. Again, time dilation at light speed reduces time to zero, not three years. Heeck perhaps is postulating that light moves at sub-light speeds. They talk about a photon aging that three years in the inertial reference frame of the photon. If it had a valid inertial frame, it would be at rest in it, thus contradicting the statement earlier that light cannot be at rest.

The article mentions nothing about gradual degradation/dissipation over distance. It just postulates a spontaneous decay into components after far more time than it takes for light to redshift into undetectability in whatever frame the distant observer is likely to be in.

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

Post by Greta » Fri Nov 18, 2016 6:33 am

Noax wrote:The article mentions nothing about gradual degradation/dissipation over distance. It just postulates a spontaneous decay into components after far more time than it takes for light to redshift into undetectability in whatever frame the distant observer is likely to be in.
For me it's the principle of the thing. As far as I can tell, nothing in nature is forever or infinite, so I expect that photons will eventually degrade, even if we haven't found the mechanism for their breakdown.

I simply don't believe in absolutes, not in nature - not true singularities, nor infinite expansion, nor infinite gravity in black holes, nor infinite atoms, nor even immortal creators or massless(?) particles. I find it more in keeping with the way nature works for dissipated energy from degraded photons to revert to an unfamiliar energy state than for them to continue as immortal agents after everything else is gone.

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

Post by Justintruth » Fri Nov 25, 2016 12:31 pm

Of course we are already going faster than that relative to some imaginary point moving at twice the speed of light but...

If special relativity is right then you can't do it. If not who knows.

But...if you want to see why relativity says you can't. ...

..you look at a two dimensional space time drawing with the wold lines of two light rays emanating in opposite directions from the origin and also a world line of the origin of a frame of reference going at some velocity v in the positive x direction.

Now you can see how for any given time relative to that frame, the light going in the plus x direction is closer to the moving frame origin than the light going away. In order to fix this relativity assembles events in the past and future relative to the stationary frame. You can daw a line across the light cone so that the intersection of the line and the world line of the moving frame bisects the segment of the line between the sides of the light cone. As measured along any line parallel to this line light is getting just as far ahead of the moving frame as it is getting behind. Relativity defines things so that events along this line equidistant from the moving frame are simultaneous relative to that moving frame. This allows c to be the same for two frames moving relative to each other.

Now increase v. You will see that line needs to reach farther and farther into the past and future relative to the stationary frame in order to come up with events that are on the light cone and equidistant from the moving origin.

If you reach light speed there are no events that can be had no matter how far you go into the future.

The idea that mass is involved is true but is a consequence of this fact.

As long as you are going just a little less than light speed there is always a place in time and space where the light will be as far away from you in front as it is in back. So light can be constant reative to the two frames moving with respect to each other just by choosing the right events. But if you go at light speed the light never gets ahead of you. So there are no events in the future no matter how far you go that you can assemble into a present that has the speed of light the same in the forward direction and reverse.

If light is barely beating you it will be getting slowly ahead of you and given a long enough time will pull ahead to any distance ahead of you you can think of...at least at some distant future time. You can then just select the light events that are as far ahead of you as the event where the light going the other way is and call them simultaneous. Then light moves in the direction of motion just as fast as against the direction of motion relative to the moving frame . But reach the speed of light and the light can't get ahead. So the speed of light in the direction of motion cannot be c in both directions.

Everything else follows from this...including the energy and mass descriptions.

How did Einstein come up with this? Fortunately he couldn't get a job teaching so he had to work in the Zurich patent office. Switzerland. Swiss clocks. Patents on devices that synchronize Swiss clocks. Perfect place. Absolutely perfect place to be.

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

Post by Noax » Mon Dec 05, 2016 3:35 pm

Greta wrote:For me it's the principle of the thing. As far as I can tell, nothing in nature is forever or infinite, so I expect that photons will eventually degrade, even if we haven't found the mechanism for their breakdown.

I simply don't believe in absolutes, not in nature - not true singularities, nor infinite expansion, nor infinite gravity in black holes, nor infinite atoms, nor even immortal creators or massless(?) particles. I find it more in keeping with the way nature works for dissipated energy from degraded photons to revert to an unfamiliar energy state than for them to continue as immortal agents after everything else is gone.
I've decided you're right. Anybody can mathematically select a reference frame that gives an acorn planetary mass, but it doesn't really do anything to the acorn. That's what I was doing with my eternal undegraded photon: mathematically assigning it an increasingly meaningless reference frame. In practicality, the wavelength gets longer and longer, the energy less and less, until it is incapable of interacting with any matter at all. It fades away, never all the way to zero, but arbitrarily close to it.

Long time no respond, I know.

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

Post by Greta » Mon Dec 05, 2016 11:11 pm

Noax wrote:
Greta wrote:For me it's the principle of the thing. As far as I can tell, nothing in nature is forever or infinite, so I expect that photons will eventually degrade, even if we haven't found the mechanism for their breakdown.

I simply don't believe in absolutes, not in nature - not true singularities, nor infinite expansion, nor infinite gravity in black holes, nor infinite atoms, nor even immortal creators or massless(?) particles. I find it more in keeping with the way nature works for dissipated energy from degraded photons to revert to an unfamiliar energy state than for them to continue as immortal agents after everything else is gone.
I've decided you're right. Anybody can mathematically select a reference frame that gives an acorn planetary mass, but it doesn't really do anything to the acorn. That's what I was doing with my eternal undegraded photon: mathematically assigning it an increasingly meaningless reference frame. In practicality, the wavelength gets longer and longer, the energy less and less, until it is incapable of interacting with any matter at all. It fades away, never all the way to zero, but arbitrarily close to it.

Long time no respond, I know.
Take as long as you like :). As departed forum member Obvious Leo used to say, there's a tendency to focus on mathematical models. This can mislead us towards infinites, which only seem to appear in nature in fractal form, but are otherwise considered to be a sign that there's a problem with the equations.

About your acorn example, I'm wondering about relativity in the projected late stage universe (the Dark Era) when there are only ultra long wave photons still in existence.
Wiki wrote:... with only very diffuse matter remaining, activity in the universe will have tailed off dramatically, with very low energy levels and very large time scales. Electrons and positrons drifting through space will encounter one another and occasionally form positronium atoms. These structures are unstable, however, and their constituent particles must eventually annihilate.
Spacetime at this point will differ from the familiar and observed mix of EM, gravity waves and nuclear forces. This space will be much closer to actual emptiness, very close to absolute zero everywhere. In the light of this, considering the relativities, wouldn't that mean a budding positronium atom is just as intense in comparison with its surrounding nothingness as the "singularity" that preceded the BB?

When surrounded by complete nothingness, what relativities can be applied to differentiate the scale of a positronium atom, an acorn, a star or galaxy? In each instance, it would seem that the entity is almost infinitely more dense and energetic than its surroundings. Would our current laws of physics still be relevant in such as extreme situation?

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