Faster than C

Is the speed of light supposed to be a constant and absolute

Yeah, that's the point. c=3x10^8 is one of three universal constants (G=6.67x10^-11 and h=6.626x10^-34) that are... constant.

At any rate, velocities don't add that way at high speeds. They follow a more complex formula for addition that appears to be simple addition at slow speeds. This website explains it, but the formula is as follows:

w = (u + v)/(1 + uv/c2)

Where
w=velocity of A relative to C
u=velocity of B relative to C
v=velocity of A relative to B

As I recall, there was a specific solution to the equations of general relativity that allowed for FTL travel. I'm too lazy to go running around the internets looking for it, but chances are you'll find it somewhere. Unfortunatley, it required imaginary mass... here's a simple explanation for those who are intersted in such things...

*drumroll*

for reference, I'm using y as gamma (1/sqrt(1 - v^2/c^2), E for total energy, p for momentum, the rest should be obvious...

E = ymc^2 (m here being m-naught, obviously...)
p = ymv

so v/c = p*c / E

for FTL, we want v/c > 1, therefore E < p*c, or E^2 < p^2 c^2

but we know energy is also E^2 = p^2 c^2 + m^2 c^4
so for the above condition to be true, m^2 must be negative
therefore, we have imaginary mass (remember that i^2 = -1)

And there you go, if you find something like that, you have yourself a tachyon... interestingly, the way the equations work out, they live in a "mirror world"... it takes energy to slow them down to c, and they can never go slower than c. However, chances are they either don't exist or we can't interact with them due to the c barrier... anyways, just food for thought. enjoy.

Originally posted by SilentFrog
Unfortunatley, it required imaginary mass

Well that's the same as my imaginary time thing. It don't happen.

Tachyons are nonsense, don't let anyone say otherwise.

First the bad news. If you go fast enough- even if the atoms, dust, gravel, rocks and boulders (let alone planetoids) don't hole you-

The Unruh Effect can ruin your whole day.

As you go faster, you run into all kinds of stuff that generates radiation as it hits your ship's nose. Including the zero-point fluctuations themselves.

Shields? I wish. Please, invent them. We will pay you handsomely.

The good news is- this radiation spray might hold promise as a power source for a kind of 'ultimate Bussard ramjet'- but how you could shield (non-genetically engineered) people in such a hellbat is beyond me. Even if it was as big as Iapetus.

A fast starship has got to be one hell of a fireworks display- if it remains in our spacetime (!). Physics seems to favor very patient, very slow, very ponderous worldships. For now.

We have a long way to go before we can make a fast leap to the Stars.

There is but one hole in the theory of relativity, and its a Black Hole.

Relativity cannot account for the existance of black holes, but they have been proven to be existant based on evident of accreation disks.

No one knows what would happen to light if it entered a black hole, since it seems to pull things faster than even light.

So perhaps you could go faster with a "black hole" donut to propel you. Of course, think of the logistics and sheer absurbity of building something like that.

And there is no proof it would work.

Originally posted by Raideur

So perhaps you could go faster with a "black hole" donut to propel you. Of course, think of the logistics and sheer absurbity of building something like that.

And there is no proof it would work.

Why not just use the ones we have? Like how we use planets gravity for satalites....use blackholes for ships....now thats a scary though. I don't think anyone would ever be able to fully trust even the best calculations lol. If you are too close by any amount of space you would be nothing. So maybe not that.

Originally posted by Raideur
since it seems to pull things faster than even light.

No it doesn't. It just has a strong enough gravity such that you need to go faster than light in order to not fall into it. Gravity "doesn't pull."

So perhaps you could go faster with a "black hole" donut to propel you. Of course, think of the logistics and sheer absurbity of building something like that.

It wouldn't work because you can't. You could use a black hole to accelerate you, though, much like what is stated above. It's still dangerous.

Ugh, can 'o worms time...this is a problem that is very tough to solve.

The Big Issues are causality and energy.

Most of the mathematcially consistent ways one might violate c also violate casuality. That means that you start having effects before causes, which is impossible in physics as we know it.

The other issue is that as speed increases, so does effective mass. This in turn increases inertia, which makes any change in velocity cost increasingly more energy. To the point where just getting *any* mass to c costs infinite energy. Not a winning proposition for spacecraft designers.

Most of the research in this area seems to be focused on some type of "warp" drive. This does not violate any of the laws of physics, because no movement is involved to violate causality or energy requirements. Instead, space itself is warped, "gathered up" in front of the craft and "stretched out" back behind it. This allows the craft to change position in the Universe without actually moving at all. The problem is, nobody really knows how space might be warped using technology. There are a lot of theories involving gravitation and electromagnetic fields, but no firm answers.

MY personal opinion (as a layman in physics), is that we will find some correlation between electromagnetism, gravity, and inertia. If this problem is solvable, I think it will be by using EM fields to create gravitic propulsion, and simultaneously lower (or cancel) inertia. If inertia is sufficiently lowered, a tiny energy input could accelerate the craft to almost infinite speed. Since there is no inertia, there is no damage to the occupants. Also since inertia is the cause of rising energy costs with velocity, the maximum speed above c might only be limited by the degree to which inertia is canceled out. And since collision energy is also based on inertia, collisions with small objects would also have less inpact energy commensurate with the degree of inertial modification.

Just my gut feeling on this, but I think it is consistent with the alternative research we're seeing in EM fields, superconductors, gravitics and inertia.



[edit on 24-6-2005 by MrMorden]

Dragging this back up from the archive.....

Tesla did have some choice words to say about the speed of light being all that....

The Literary Digest
Nov. 7, 1931

No High-Speed Limit, Says Tesla

Dr. Nikola Tesla asserted in an interview with Hugo Gernsback that speeds greater than that of light, which are considered impossible by the Einstein theory of relativity, have been produced.

Stating that the Einstein theory is erroneous in many respects, Dr. Tesla stated as early as 1900, in his patent 787,412, that the current of his radio-power transmitter passed over the surface of the earth with a speed of 292,830 miles a second. According to the Einstein theory, the highest possible speed is 186,300 miles a second.

Tesla indicated knowledge of speeds several times greater than light, and had apparatus designed to project so-called electrons with a speed equal to twice that of light.

Tesla disagreed with the part of the Einstein theory which states that the mass of an object increases with its speed. The mass of a body is unalterable, contended Dr. Tesla, According to the article, "otherwise energy could be produced from nothing, since the kinetic energy acquired in the fall of a body would be greater than that necessary to lift it at a small velocity."


www.tesla-coil-builder.com...

And to argue with Tesla is like arguing with God imo.... If a given person considers Einstein brilliant i do not think a word in the dictionary could sum up Tesla....

Stellar

As far as I know, there is nothing in physics that proves beyond doubt that faster than light speeds cannot be obtained. There IS, however, a mathematical proof that can be derived that says beyond doubt that information cannot propagate at faster than light speeds. So the absolute maximum for speeds in computers, fibreoptics, etc, is light speed.