Why can't we overtake the speed of light
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Why can't we overtake the speed of light
Hmm.. we can if we cheat!
I've forgotten the explanation of the "light speed limit" but you'll find it on Wikipedia.
It is possible to get around the speed of light by various methods, the simplest (and perhaps most improbable) example is building a spacecraft of enormous proportions and accelerating it close to the speed of light, then send a tiny craft flying from one end of the mothership to the other - ie; 99% light speed + an extra 2%... hardly a practical solution, but to an observer outside the ship, the tiny craft inside would be travelling at a total of 101% the speed of light.
Lorddarklaw, you're forgetting that the tiny spaceship would have a nearly infinite mass, and so would need an infinite energy to break the speed of light.
It's not surpassable by the method you put forward.
This is why it is a speed limit, as you approach the speed of light, your mass becomes greater and so more energy is needed to accelerate you further. As you reach the speed of light, you need an infinite energy to accelerate you further, this is currently unphysical and impossible.
Hello ash:Quote:
Originally Posted by ashishhawking
We can. We used to think nothing can go faster than light. We were wrong.
excon
Capuchin, it's just an example - you could theoretically use hundreds of ships one inside another like a Russian doll. Other methods of beating the speed of light involve using worm-holes, or bending the laws of physics (way beyond anything I can think about).
Yes, and it cannot be used to beat the speed of light - your last ship will have infinite mass.
Wormholes are just "shortcuts" through spacetime, you might be able to beat a photon in a race, but you will never travel faster than light.
For example, I put a mirror on the moon and I race the photon from where I am standing to a point 1 meter away from me. I shoot the photon towards the mirror and then run for the finish line, the photon takes several seconds to get there, and I beat it.
Does this means I've travelled faster than the speed of light? No. The same is true with worm holes, the light will obey the curves of space-time, but by using intelligence, we can beat it by using shortcuts.
Excon I would like to hear about your schemata for faster-than-light travel
Hello Cap:
I was hoping you wouldn't ask. However, I recall falling asleep in front of my TV watching the Science Channel, and I heard (in the netherworld just before sleep) that they now can go faster than the speed of light.
I don't know who "they" are, and I don't know how they do it. But, I believe they are doing it.
excon
Should we be worried?
Regularly happens in Star Trek. Ask them!
Hello Cap:
Nahh. The only thing that worries me, is the science that I was taught as a kid. I was told things that aren't true, and I was taught them as though they were.
I was taught that the speed limit in the universe is the speed of light. I think that's as true as any statement is, before it's proven untrue.
excon
Oh yes, there are a number of phenomena that do propagate faster than light (and I'm surprised nobody has brought them up yet), but nothing that (as the OP asked) means "we" can travel faster than light. Taking "we" to mean humans on the macro scale.
Dumbing down of science is one of the essential evils of science education, you just cannot comprehend the truth at that age without better mathematical knowledge.
Hello again:
I don't know if it had to do with dumbing down. I just think I was taught what they knew at the time, but that what they know changes pretty fast these days.
Specifically, I'm speaking of plate tectonics. Of course, South America looks like it fits into Africa, but my teacher said it didn't. Whoa, ho ho on her.
excon
I know that a lot in physics changes as you reach the different levels of education.
Now plate tectonics I have no idea of the history of :) (or how old you are) ;)
Hey I'm almost finished reading A Short History of Nearly Everything by Bill Bryson and he speaks directly to this issue. Great book if you love science.Quote:
Originally Posted by excon
The ABZ of Relativity
Also an interesting sience book :)
How about a ship powered by Hawking radiation, the only thing that can escape a Black Hole?
Even light can't do this!!
Hawking radiation is produced from outsied the event horizon - light CAN escape from points outside the event horizon.
Hawking radiation is just thermal radiation, but it's created by means other than black body spectra. Thermal radiation = photons = light. THerefore it moves at the speed of light.
Hello again, Cap:Quote:
Originally Posted by Capuchin
Ok, what are they? Something to do with strings? Or things that happen in a particle accelerator?
excon
excon, I missed that bit from Cap.
Well I have one.
How about Tachyons??
Oh now this is good reading Faster-than-Light.
Oh no, normal light will have a phase velocity faster than the speed of light if you have a material with a refractive index less than 1.
This means that the front edge of the group of photons moves faster than the speed of light, however, it's impossible to transfer information this way (at the moment) because the information is spread out over the whole group (this is the group velocity) (so you have to wait for the end of the group to arrive, which arrives at the speed of light). So it doesn't break any rules.
Particle accelerators routinely accelerate particles to something like 0.99c.
Tachyons might actually be the one thing that can move faster than the speed of light. These are theoretical particles that have not yet been observed. The theory is that while you cannot accelerate something beyond the speed of light, If something was created with a superluminal speed, then it could happily exist in that state forever. This is of course contraversial and nobody knows if they exist or not.
Edit: Yes curlyben, tachyons, but they might not even be real :)
Is it true that if u circle around earth at some speed, u are younger than u would be at earth. I think its called a twin pharadox. Can someone explain in plain english.
Thanks.
What about black holes? In theory, you could say light, when being sucked into black holes, eventually reaches a speed of zero, so therefor, You could go the speed of some light right now. But there's probably some counter example you could give to prove me wrong. I really have no idea about what I am talking about.
Let me clarify and add at the same time. Is it possible to go as fast, or if not faster than light if:
1. light passing a black hole (not going directly at it) could be bent, eventually slowing the speed of light, making you faster than some light?
2. you yourself were sucked into a black hole (even though you would end up in quintillions of pieces)?
A black hole is no different than any other massive object in space, it is just so dense that there is a point called the event horizon, past this point we have no idea what happens. Physics may be totally collapsed. The gravity isn't any stronger or greater than any other object of that mass, it's just small enough that the event horizon is OUTSIDE the object.
We are talking about moving faster than the speed of light in a vacuum. There are materials we have on earth that can slow light to a few mm/s, I can easily run faster than that, would you say I can run faster than the speed of light?
I'm curious as to why light travels at the speed it does - I've had a quick look on Google but the answer seems to be "it just does". :confused:
There must have been a point in time before the speed of light was set, which makes me wonder if the mechanism that set the speed of light could be reproduced... could it be used to change the properties of light? Trippy thought. :)
Massless particles always move at the speed of light :)
(Tachyons move faster than the speed of light, because they have imaginary mass)
I don't think it's right to say that light decelerates to 0 within the event horizon, worthbeads, you're treating it like a normal particle.
It merely follows the curve of spacetime, which is curved in such a way that light cannot navigate a path to a point outside the event horizon.
Another consequence of quantum mechanics is that light can move faster than the speed of light over very short distances, it only moves at the speed of light on average.
It may also be possible to make a photon move faster than the speed of light between Casimir plates. Thse are plates that are brought together such that there is less than an atomic diameter between them. The vacuum between these plates is perfect, and may even not contain Zero-point energy. If there is no Zero point energy, the vacuum will be "more perfect than a perfect vacuum", and so light will be able to move faster through it. However it is not possible to measure experimentally at the current time, and so is theoretical.
That looks like what I stated before - the phase velocity is faster than the speed of light, but the group velocity is not, so you cannot transfer information this way.
But, like that article says, I'd like to see the paper first :)
I have an interesting question. Assume you are in a room covered in mirrors (all walls, floor, ceiling). You yourself are covered in a material that is 100% reflective (the mirrors are also 100% reflective). In the perfectly reflective room, you strike a match. Assuming your body, the match, and the mirrors do not absorb light and only reflect it, would the room stay lit long after the match went out? Would there be a limit on how bright it would be inside the room?
Your eyes would absorb photons in order to see them, so, do you want to go into "if you light a match in a perfectly mirrored room, but nobody is there to see it, is it lit up"? :P
Also, any gas in the room would also attenuate the light fairly quickly.
I am aware eyes absorb light. Just assume no person is in the room.Quote:
Originally Posted by worthbeads
Okay well the atmosphere in the room absorbs it then, if you had perfect vacuum, then the brightness in the room would be proportional to the amount of time you left the match lit for as long as forever.
Would it keep getting brighter and brighter, with no limit?
Until the fire runs out of fuel.
Pardon if this is old news...
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Social Ecology Eclectic : Light exceeds its own speed limit, or does it?
Yes, I did mention this earlier in the thread. There is no evidence that information can be transferred faster than light using this method.
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