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W∴ Balboos wrote: Phase velocity can exceed the speed of light
True, but it can't be used to transfer information.
Many other things can also "travel" faster than light; for example, a laser dot shined onto the moon will, if the laser is moved at more than ~43 degrees of arc per second, "appear" to move faster than light. However, this dot cannot be used to transfer information.
W∴ Balboos wrote: It all comes down to the relativistic mass of any object with mass.
I am well aware that Special Relativity does not allow travel at faster than the Speed of Light. I was speculating on the possibility that a marriage of General Relativity and Quantum Mechanics would allow for FTL travel.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Not sending information via phase velocity at greater than c: I had that explained to me ca. 30 years ago. I had suggested a physical device, essentially a giant scissor, which could open and close and non-relativistic velocities with respect to it's physical form, but the point at which the two parts of the scissor meet (a phase) moves faster than the scissor if the scissor is long enough.
So - make the scissor long enough so that the intersection exceeds c whilst no actual parts do - but the signal is sent from end-to-end by observing the motion of the tips of the scissor.
The physicist said what would happen is that the scissor would actually bend (relativisticly) to prevent the signal from exceeding c. This would, I suggest, connect with your wording "appear" to exceed see with your laser-spot-to-the-moon concept.
But wait! Stuff does exceed c under certain circumstance: if moving at c to begin with, a photon entering a new medium with a higher index of refraction will, momentarily, exceed see. This is observed as the bluish glow observed in the cooling water around a nuclear reactor (Cherenkov radiation). So - their is ever so small a chink in the armor of no-way, albeit admittedly it wouldn't help out much if traveling in a vacuum.
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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W∴ Balboos wrote: if moving at c to begin with, a photon entering a new medium with a higher index of refraction will, momentarily, exceed see.
Special Relativity does not forbid a photon (or other particle) moving at higher than the Speed of Light in a medium. It only forbid moving faster than the Speed of Light in vacuum.
EDIT: As for the scissors' blades, the question is - what started them moving? The signal that the part of the blade closer to the join is rotating cannot move faster than the Speed of Light, so at any time - the blade will not be moving faster than light. Note that this problem involves acceleration (any point on the blade is moving in a circle), so it can't be solved by using Special Relativity.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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So, now I have a question:
One is in a medium with n > 1 looking out into a medium with a lesser n
How does the external light appear to them from the point of view of their higher n medium?
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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Light (but not necessarily other particles) is affected by a move between media. You get effects such as refraction, total reflection, etc.
If you want to see how the outer world looks when looking out from a medium where n > 1 to a medium where n == 1, dive into a pool and open your eyes. Experiment always trumps theory. 
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Daniel Pfeffer wrote: Experiment always trumps theory.
So theory is fake news! 
CALL APOGEE, SAY AARDWOLF
GCS d--- s-/++ a- C++++ U+++ P- L- E-- W++ N++ o+ K- w+++ O? M-- V? PS+ PE- Y+ PGP t++ 5? X R++ tv-- b+ DI+++ D++ G e++>+++ h--- ++>+++ y+++* Weapons extension: ma- k++ F+2 X
Never pay more than 20 bucks for a computer game.
I'm a puny punmaker.
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Yes, until it is verified by experiment.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Except I'm interested not in the classical view but the relativistic view. What is 'The c' from my point of view of light in the lower-index medium?
From the reverse situation, 'The c' is slower in the higher index medium when viewed from the lower index medium. Do I see, for exemple, a Cherenkov radiation view of all outside light?
Your "do the experiment" works if I were to look up at stars from earth. OK: let's pretend for a moment that it is a Cherenkov radiation view: the effect could be trivial, too dim, or radiating elsewhere than toward my point of observation. The pretend, of course, can be wrong. What I see is what I've always seen - so I'd not know.
I'd imagine someone has considered this by now - but I'm at work and can't go off on this particular google search right now. Seeking that quick-answer. (Should I post this in Q&A ?).
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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What you see when you dive into a pool is the relativistic view; do you think that when you jump into a pool that you are suddenly transferred into a Newtonian Universe?
(Note that it is impossible to treat light in any manner other than relativistic. The Theory of Special Relativity was formulated in order to resolve the non-Newtonian behaviour of electromagnetic waves).
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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My view, insider or outside of the pool is still (for all practical purposed) the normalized perceptions. My interest was in how a totally relativistic entity, light, would appear from a different point of view - not as I see it with eyes.
This is a theoretical view that I'm wondering about. If I "perceive" light moving slower than 'c' as it moves through a higher index medium than that from which I observe it, what would I observe if the media were switched? Could I thereby "observe" light (in the lower index medium) exceeding "my local c" ? Observation here does not refer to human perception: what would I measure from my frame of reference?
I'll look it up, later.
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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W∴ Balboos wrote: Observation here does not refer to human perception: what would I measure from my frame of reference?
They are one and the same; what you see is (or should be) what Physics predicts that you see.
If you are asking "what would it look like to a photon that entered a medium where n > 1?", I can't answer that. It's an interesting Gedanken experiment...
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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I thought it was only things with mass that cannot travel faster than the speed of light, but it is possible for things without mass to exceed the speed, even in a vacuum.
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Nope. Massless objects (such as photons) are constrained to always move at the Speed of Light (when they are in vacuum). When is a different medium, such as water, they may move slower than the Speed of Light, but never faster.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Tachyons are considered impossible in Special Relativity - they can send information into the past, and so reverse cause and effect. In a Universe where Tachyons existed, it would be possible for you to kill your grandmother before your mother was born, thereby making you disappear - poof!
There was a young woman called Bright
Who could travel much faster than light
She went out one day
In a Relative way
And returned the previous night
-- Anon.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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Yeah, fair enough, I guess unless a hypothetical particle has been observed we must assume it is impossible.
I wonder what they're doing with the LHC these days....
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mass increases with velocity? You must live in a different reality then the rest of us.
Relativistic mass =/= mass.
Sin tack ear lol
Pressing the any key may be continuate
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Two objects pass each other with 0,6*c (like trains that go in different direction) and from either of the object it would "look" like you pass each other with 1,2*c ? Now the question is would you see the other object passing?
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Nope. Adding relativistic velocities is not simple addition. See Special Relativity - composition of velocities
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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HobbyProggy wrote: from either of the object it would "look" like you pass each other with 1,2*c ?
No. That's actually from a gedanken experiment written up by Einstein with respect to light on a moving train, etc.
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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Oh he did that? Didn't know 
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W∴ Balboos wrote: as anything with any mass approaches c, they all approach the same mass
The problem here is that you are treating infinity as a quantity, which leads to all sorts of paradoxical things. Infinity is a concept not a number, it has no quantity that can be compared to some other quantity. This is why mathematicians talk about approaching infinity rather than infinity itself as a number.
Besides, before the object approached "infinite" mass, the universe would collapse around it and destroy everything anyway, because gravity. You would destroy the universe before you approached the speed of light, even leaving aside the fact that you used up most of the energy in the universe in the process.
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I did say approach, and besides that, these are both approaching the same order of infinities (Alephs).
The universe wouldn't collapse around it - if for no other reason than that the information about it's mass would still be constrained to traveling at c. Anything else moving at 'c', therefore, may never know of the event unless it's heading more-or-less towards it.
Or - if I were politically motivated I'd say: you've no experimental proof - but one doesn't present politics in the Lounge.
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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I'm not clear on how bringing set theory into it changes things. The initial energy required for acceleration would be much greater for the planet than for the grain of sand, so that is still going to carry forward as you approach infinity, right? It would amount to the same energy in both cases if you actually reached infinity, but of course you never would.
Also, I'm not clear about how that mass is going to effect (or not) the rest of the universe. Are you saying that there would be no gravitational force exerted on the surrounding universe as a near-infinite bit of mass passed by? Is the gravity somehow localized? Let me guess, relative to the object travelling at c? So would the spaceship crush itself then? I'm sure I'm missing something, but I can't help but see near-infinite mass as near-infinite gravity, and gravity on that scale seems like it would have an effect on something.
And, experimental proof of what? We're talking about thought experiments.
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The set theory view is to narrow – they infinities are of the same order of magnitude (infinity-wise). Now, be they a grain of sand or a planet, they rapidly converge, asymptotically in mass as the sand would accelerate much faster (at first) until it’s mass was the same as the planet. Catch-up. The energy required for acceleration of either is "within experimental error", the same. (You know - infinit vs. infinity+1)
And I didn’t say “space ship” or any other specific object traveling at ‘c’. Take, for example, any light in the universe – which is part of the universe – and would always be out of reach of the gravitational waves (if they travel at ‘c’). Unless you consider a universe containing just light is not a universe.
The ‘experimental proof’ was a jab at those saying there’s no ‘experimental proof’ for climate change – but what experiment would the propose? So that’s why I said it had a political scent to it. Now, I’ve had to spell it out – which is what I tried to avoid, before – I brought a ray of darkness into the Lounge.
| Ravings en masse^ |
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| "The difference between genius and stupidity is that genius has its limits." - Albert Einstein | | "If you are searching for perfection in others, then you seek disappointment. If you are seek perfection in yourself, then you will find failure." - Balboos HaGadol Mar 2010 |
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