Is it possible to exceed the speed of light?

[stallion x1]

Am i right in saying that speed is only relative to the location of the observer....

So therefore if you were to accelerate object "a" at .5c in one direction and object "b" at .5c in the opposite direction then surely from the view of an observer on object "a" the speed of object "b" would be the speed of light.....

Im guessing they is some sort of massive problem with this idea that i haven't noticed so please tell me...

[Kerbart]

Yes, you assume time is constant. Einstein's genius was that he realized it wasn't. We could be moving away from each other at half the light speed, and you could point at flashlight at me. If you'd measure the speed at which the light leaves the flashlight, it would be 300,000 km/s (give or take). And when I would measure the speed of light that I'm receiving from your flashlight, it'd still be 300,000 km/s. Look up "special relativity" on wikipedia.

[Nachtwind]

Well.. the way i understand it you would always see just a static image of "a" and later no "a" anymore when you reach a "date" before the start..

[Spica]

Once, I was seriously messing around with hyperedit, and deciced to put myself in a 5 km orbit above jool's "surface". When i did that, before physics loaded, I inflated my airship envelpoe, and one of the Kraken's long lost children propelled me out of the solar system at 12,700,000,000,000,000 times the speed of light. Then I heard an SSTV signal.

This is only in ksp though.

[Holo]

Am i right in saying that speed is only relative to the location of the observer....

So therefore if you were to accelerate object "a" at .5c in one direction and object "b" at .5c in the opposite direction then surely from the view of an observer on object "a" the speed of object "b" would be the speed of light.....

Im guessing they is some sort of massive problem with this idea that i haven't noticed so please tell me...

Relativity means that velocities don't add up in the way you expect.

[stallion x1]

Ok thanks the responses i now see the bit i got wrong makes sense now..... (Sort of)

Edited September 29, 2013 by stallion x1
*now not know*

[Rjhere]

There's no way we can know, as we stand in our understanding of physics today, no. But there's been progress recent years saying Einstein's relativity theory and even special relativity is wrong, so there are probably things we haven't discovered yet.

Also there's a theoretically posibility that we might be able to bend space and time around a spacecraft, making travelling "faster" than light a probability. And there's been recent development in this concept wich makes it half as power hungry, now only requires 20 grams or so of anti-matter to travel to Proxima Centauri!

Though this are not proven in any ways, I find this concept to be exciting! And there's alot of theories that are promising theoretically, but right now we're stuck at a speed record of .1%C, one thousandth of the speed of light! A quick google says it was the Helios 1 or 2 that achieved this.

[GregoryNeal]

Am i right in saying that speed is only relative to the location of the observer....

So therefore if you were to accelerate object "a" at .5c in one direction and object "b" at .5c in the opposite direction then surely from the view of an observer on object "a" the speed of object "b" would be the speed of light.....

Im guessing they is some sort of massive problem with this idea that i haven't noticed so please tell me...

If you were sitting in a reference frame where you could observe A and B traveling in opposite directions at .5c, then the gap between them would expand at c, that part is feasible. However, when you are standing on A or B, things get a little more complicated. A would not see B as traveling at the speed of light, nothing (with mass) can reach the speed of light You need to use the Lorentz Velocity Transformations to find out how fast B will be going in A's frame. It turns out that when A looks at B, it seems as though B is traveling at exactly .8c, and since they are traveling at the same speed (in opposite directions) with respect to you, then B sees A as going .8c as well. Velocities do not add up the way you would expect when you get to high speeds, this is because the speed of light is constant for everyone, and because there is no preferred frame of reference from which you take your measurements.

[WestAir]

I believe the correct formula here is:

u' = (vb-va)/ (1-vbva/c^2))

U' is the end velocity [The answer to your question] that we're trying to learn. Va is the velocity of rocket A from A's perspective, vb is the velocity of rocket B from rocket B's perspective.

u' = 1c / (1-(0.5c)(0.5c)/c^2)

u'= 1c/(1+0.25c^2/c^2)

u'= 1c/(1.25)

u'= 0.8c

So to answer your specific question, the two rockets will approach at 0.8C from each others perspective, rather than the speed of light. With the formula you'll also notice that it's impossible to approach at faster than C with values lower than c, because you have to multiply the two values, and multiplication of values smaller than 1 will always lower the value. For instance, 0.999 x 0.999 = 0.998. At no time can the value be greater than 1, or in this case, c.

[lajoswinkler]

There's no way we can know, as we stand in our understanding of physics today, no. But there's been progress recent years saying Einstein's relativity theory and even special relativity is wrong, so there are probably things we haven't discovered yet.

Also there's a theoretically posibility that we might be able to bend space and time around a spacecraft, making travelling "faster" than light a probability. And there's been recent development in this concept wich makes it half as power hungry, now only requires 20 grams or so of anti-matter to travel to Proxima Centauri!

Though this are not proven in any ways, I find this concept to be exciting! And there's alot of theories that are promising theoretically, but right now we're stuck at a speed record of .1%C, one thousandth of the speed of light! A quick google says it was the Helios 1 or 2 that achieved this.

Einstein's theory of special relativity is not wrong and will never ever be prover wrong. It works, therefore it's correct. It is used in GPS, Mercury's orbit was explained using it, etc. It works.

It can only be insufficient, and it really is, as all scientific theories are. Every new correct theory is a better explanation of a phenomenon, but the quality of the explanation is only asymptotically reaching 100%, just like an object with mass when it's trying to reach c.

There are phenomena that show speeds >c, but they can not give valuable transfer of information (in the basic physical sense) at >c.

If a body has resting mass, it will not travel at speeds close to c today. That's the basic wisdom of this universe. The "bending space spacecraft" are nothing but an idea based on "wouldn't it be funny if". It's a totally naked concept without any practical value. As things are at the moment, we'll be stuck in the Solar system forever. That's the reality.

[K^2]

There's no way we can know, as we stand in our understanding of physics today, no. But there's been progress recent years saying Einstein's relativity theory and even special relativity is wrong, so there are probably things we haven't discovered yet.

No, there are not. We have not found a single case where GR fails. In fact, it remains the most precisely tested theory we have.

But GR itself provides loopholes. Speed of light is a local limit in GR. That means nothing in your immediate vicinity can move faster than the speed of light, but if two objects are separated by some distance and the space-time is not flat, you can have relative speeds exceeding the speed of light. This is the very principle behind the warp drive.

[NGTOne]

No, there are not. We have not found a single case where GR fails. In fact, it remains the most precisely tested theory we have.

But GR itself provides loopholes. Speed of light is a local limit in GR. That means nothing in your immediate vicinity can move faster than the speed of light, but if two objects are separated by some distance and the space-time is not flat, you can have relative speeds exceeding the speed of light. This is the very principle behind the warp drive.

It's actually believed that there may be naturally occurring regions of spacetime where local apparent velocity (from the PoV of a stationary observer outside the region) is greater than c. Around a rotating black hole, there is a region called the ergosphere, where spacetime is "dragged" (for lack of a better term) in a rotary fashion at greater than c. Now, if your spacecraft were to suddenly appear there, you would feel like you were standing still. However, from the point of view of an impartial observer located outside the black hole's SoI, you would appear to be moving faster than light (around a cosmic drainpipe, but that's a whole other story).

[WestAir]

Doesn't warp break causility too, but is still allowed by Gr?

Edited October 2, 2013 by WestAir

[-Velocity-]

No, there are not. We have not found a single case where GR fails. In fact, it remains the most precisely tested theory we have.

But GR itself provides loopholes. Speed of light is a local limit in GR. That means nothing in your immediate vicinity can move faster than the speed of light, but if two objects are separated by some distance and the space-time is not flat, you can have relative speeds exceeding the speed of light. This is the very principle behind the warp drive.

But, you have universe-shattering causality and consistency violations, such as what I posted here:

http://forum.kerbalspaceprogram.com/threads/44835-Higher-time-warp-and-hibernation-instead-of-magic-unrealistic-warp-drive-o-O?p=612192&viewfull=1#post612192

A warp drive gets around the limitation of not accelerating anything faster than the speed of light, but it still represents a form of FTL communciation. Thus, warp drives make it possible for two observers to see different physical events take place, and compare notes with each other, and thus, see and interact with a different physical reality, even while still interacting with each other. In other words, magic. Since I don't believe in magic, I don't believe in warp drives either. If they are truly allowed in theory, it is only because our theories are not yet complete.