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Member (Idle past 4874 days) Posts: 624 From: Pittsburgh, PA, USA Joined: |
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Author | Topic: Speed of Light Barrier | |||||||||||||||||||||||
cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
I think it's better stated that the ship itself would arrive at a certain location in space faster than light would, but certainly it would not exceed light speed, right? That is a sensible way of describing the situation.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
do you see this as being plausible or just science fiction? Plausible given a sufficiently advanced technology. Mod has already mentioned Alcubierre's idea, and this was suggested before we knew of the accelerative expansion of the Universe (very odd to think that...) Dark energy is precisely the type of field we need to manipulate to generate this warp field, or create worm-holes. But we are talking engineering and energy scales on the order of stars... so say a 1000 years to get to that stage, and then another 1000 to fit it into your car
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
Why are not photons and such like particles impossibly massive? Because they are zero rest-mass partciles.
It appears that relativity does not hold good at c. Given the need for you to ask the above question, it is abundantly clear that you are in no position to make such statements. All that is clear is that you are confused. No biggie - there are not many that are not confused by relativity...
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
would an equivalent amount of energy affect spacetime any different than the original mass? Not in the sense you are thinking, but this needs mildly caveating - if the energy content of a volume is not in the form of a solid mass, then the energy distribution will be different, which will cause a different effect upon the local space-time.
Please someone elaborate on this. To create any "anti-gravity" effect (wormhole, Alcubierre warp drive, etc) you need a -ve energy density or "exotic" matter. Examples of this are Casimir energy, dark energy, and the inflaton field.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
Why can't tachyons go slower and why can't photons go faster. Is there something about space itself that imposes a limit? When you get close to c, you are no longer dealing with something that you would recognise as "speed". Speed is a concept that only makes sense somewhat *below* c. Tachyons do not "travel" in any obvious sense. c itself simply reveals our own length/time-scale within the geometry of space-time.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
From the observer’s point of view, the photon moves with measurable velocity, measurable frequency, measurable energy. Not really. You can only determine the photon's properties by its effect when it interacts with something. By that time it no longer exists. You cannot observe/measure/experiment-on photons in transit.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
I would think that for the photon the universe is a pancake and it travels 'along' its axis no distance at all, it departs and arrives instantly from the same point(s) that overlap. There is separation of the point of departure and point of arrival in our frame, but I wouldn't think there would be in the photon's frame Yes, this is essentially correct.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
With any set of axioms, you can construct a perfectly beautiful mathematics. But then unless such a construct is related to reality, it remains a curiosity. And given that SR is the most successfully tested theory EVER, I guess it is on fairly good ground
Light, like any wave [even longitudinal ones] travels at a speed limited by the medium. And what medium is light using exactly?
Can you claim it be the absolute limit for all objects? Yes, as the most successfull theory EVER demonstrates this, and EVERY particle accelerator experiment demonstrates this PERFECTLY. We accelerate protons at CERN to an energy of 7TeV. The Kinetic energy to reach c in Newtonian terms is 0.5GeV. And yet they refuse to go any faster than 99.9999991%c. Why is that? Bloody mindedness?
If you do, then you cannot have a world view broader than that of a whale. One would have a world view based upon both all available evidence and remarkably solid theory. But if you want to belive in fairies, no-one is stopping you
Mind you, if you use speed of sound in relativity equations, they will hold mathematical validity. No, they won't. An analogy is NOT an equivalence.
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
But it has not explained why the remotest galaxies are moving faster than light. Nor how 35 billion year old quasars(?) are there in 14 billion year old universe. this is child's play relativity and cosmology - the answers to these are explained in every 3rd year physics undergraduate cosmology course in every physics department around the world, every year. God knows how many times I've taught it. You seem to be making the world's oldest mistake of assuming that just because YOU don't understand something, it means that NO-ONE understands.
For long it was thought impossible to break the sound barrier. More powerful movers broke it. Different motors with even different fuels. Are you accelerating the protons with the "right" "motors"? Something that travels at c goes unlimited distance in zero time. What would you call faster than that? The speed of light is not a "speed limit" - it is the point where the concept of speed has completely broken down. Velocity is actually a rotation when looked at from the 4-dimensional perspective, but this is only apparent whne you are close to c. Asking to go faster is like asking at what angle you need to turn a 1m ruler, so that it is now 1.2m long. It is utterly non-sensical.
Whoa. Relativity is not fairy tale, sure, but it is still on shaky footings. shaky footing??? only in your head, I'm afraid
Try it then. Use speed of sound and it turns out to insurmontable. I have. I have played acoustic relativity many times with my colleagues and students. And you are wrong. But at least you are consistent.
Speed of light is a barrier, because it was assumed to be so. Err, no
Einstein had no sceintific reason to adopt it except that it was highest known speed. Oh, the cluelessness knows no bounds...
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cavediver Member (Idle past 3674 days) Posts: 4129 From: UK Joined: |
I saw this the other day, and was determined to post it here - but forgot
So thanks!!! And could it possibly be more appropriate?
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