50 replies to this topic

[A941]

Will we be able to travell faster than light?
How will this work, are wormholes possible?

[forever freedom]

Will we be able to travell faster than light?
How will this work, are wormholes possible?

Hold tight; in a few decades or centuries i come back here and give you an answer.

[synaesthetic]

I can already go faster than light, as scientists have slowed light down to 38 miles an hour in bose-einstein condensate.

Haha, ok well I know you meant "can we go faster than the current light speed limit?"

Maybe if we slow down time?:

Edited by chemflip, 26 February 2008 - 11:16 PM.

[Reno]

According to Einstein, No.

Edited by bobscrachy, 27 February 2008 - 02:03 AM.

[Luna]

The concept of traveling at light speed is problomatic nowdays
Probably yeah..

[thughes]

Faster than light seems to imply time travel.

This is easy to see with 2 people moving away from each other at a significant fraction of the speed of light: both their clocks will seem to run slow to each other. Now send something between them instantaneously. Both are sending it into the other person's past.

But, I haven't got my head around why moving *nearly* instantaneously between 2 places that are not moving away from each other at a significant speed would be a problem. It probably is, I just haven't found a good explanation yet...

- Mey

[A941]

Whats with Wormholes?
Are they possible?
What would be needed to create a working wormhole?

[thughes]

You may get a better answer to your questions here:

http://forum.physorg.com/

[Cyberbrain]

Whats with Wormholes?
Are they possible?
What would be needed to create a working wormhole?

A black hole or the equivalent of the energy of a supernova ... maybe, I don't know ... I'm an engineer not a physicist

[niner]

I have a vague recollection that some physicist or other claimed that FTL travel was "not impossible", as long as you don't pass through c. Further, I remember hearing about a "warp drive" (no, really) involving warping space both in front and behind the traveler (or ship, motorhome, or whatever) in some fashion. I think this was another one of those things in the "not impossible" category. It may be that in the future we will learn something that causes us to put these things in the "impossible" category, or on the other hand, maybe do them.

[Luna]

I think the whole concept of light speed and time travel is just misudnerstood..

It's not really time that changes, it's the objects which move slower near high gravity or acceleration.
Time dosen't really exist.

[s123]

There are particles (tachyons) that move with speeds higher than the speed of light. It is not impossible to have a speed higher than the speed of light but it's impossible to accelerate to a speed higher than the speed of light.

[thughes]

Tachyons are hypothetical, I don't believe their existence has been experimentally verified?

- Mey

[knite]

I dont think tachyons have gone past theoretical yet. As for the warp drive thing, you are correct, someone has actually worked out the math on this one, but we have no practical or theoretical way of making it happen. We have the mechanics down, but not the engine. Warp Drive Wiki

[Shepard]

Crank up the heat, baby.

[Luna]

As it was said, Tachyons are theoretical and probably do not exist.
About accelerating faster than light, as far as Enstein said, it is possible but needs huge amount of energy.

[platypus]

About accelerating faster than light, as far as Enstein said, it is possible but needs huge amount of energy.

I don't understand your sentence. Light in vacuum does not "accelerate".

[Luna]

About accelerating faster than light, as far as Enstein said, it is possible but needs huge amount of energy.

I don't understand your sentence. Light in vacuum does not "accelerate".

Was refering to what was said earlier about it being impossible to accelerate to faster than light speed.

[Andrew Shevchuk]

In my general relativity class the other day we examined a curved space that would effectively be the result of a warp drive. The problem is not that space can't be curved in such a way, the problem is with matter and the energy requirements involved to do it. As far as I know, warp-drive-like curvature is possible if you neglect things like the needed energy.

[cyborgdreamer]

About accelerating faster than light, as far as Enstein said, it is possible but needs huge amount of energy.

I thought it was supposed to need an infinite amount of energy. Which would probably make it impossible.

[vyntager]

About accelerating faster than light, as far as Enstein said, it is possible but needs huge amount of energy.

I thought it was supposed to need an infinite amount of energy. Which would probably make it impossible.

For what I've heard (but I'm no physicist), an object aways do two things at the same time : it moves in space, but also in time. The speed of the object has an effect on that moving in space and time; for all 3 dimensions of space, there is a positive correlation between speed and displacement, the faster you move, the further you'll go (in a given amount of time). For time, there's a negative correlation : the faster you move, the less you'll displace yourself in time (see minkowsi space, whose "signature" is (−,+,+,+)).

An object whose velocity woud be 0 has maximal temporal displacement, and minimal (none at all) spacial displacement. An object moving at the speed of light has minimal (none at all) temporal displacement and maximal spatial displacement.

Any speed between those two boundaries is a tradeoff between spatial and temporal displacement.

The speed of light in vacuum is 299 792 458 meters per second. I've heard, though, that this is dependent on the energy density of that vacuum, so a lower energy state vacuum could have a higher speed limit.

Apart from that, I'm like winterbreeze, I don't think time exists. So I guess we can forget about wormholes (relativity works, but the assumption time is a fundamental stuff like space, especially one that you could bore holes into, well the latter part is an assumption I think, and not a necessary one in relativity); and as far as tachyons are concerned, they are useless for breaching the speed of light, a tachyon's minimal speed is c (the speed of light), and it needs an infinite amount of energy to get there, just as any massive object needs an infinite amount of energy to get to c. I don't see how you could connect our universe of matter to a tachyonic universe then, since both have c as their limit speed, and can't ever reach it (in one way or the other.)

[cyborgdreamer]

Apart from that, I'm like winterbreeze, I don't think time exists.

In what sense do you mean time doesn't exist? We certainly don't know what exactly time is, but if we can trust our memories, there are clearly many moments that are somehow connected (the future has some relationship with the past and vice versa).

[vyntager]

In what sense do you mean time doesn't exist? We certainly don't know what exactly time is, but if we can trust our memories, there are clearly many moments that are somehow connected (the future has some relationship with the past and vice versa).

Well, some thougts about that :

Usually, we see the flow of time as past, present, and future events, past events being fixed, future events being determined by past events through causality and the laws of physics. Present is merely the boundary between those.
Ok, but what of that in a deterministic universe (classical mechanics, or quantum mechanics if you buy the many world interpretation) ? In such an universe, the future is as immutable as the past. You could as well say that the future determines the past. Except that we don't see past events as being under the influence of future ones, or, more subjectively, we don't remember the future. It intuitively feels like this is connected to causality.

So what we observe is causality, so it seems. Yet physical laws (at least classical physics) are time reversible. The only thing that prevent a broken glass to spontaneously repair itself is thermodynamics and the overall increase of entropy in any closed system. The one thing we can use to measure time flow is that anisotropy, one way entropy increases, the other it decreases.

Questions, if something could recreate a past event, down to the atomic scale (yes quantum mechanics and uncertainty will get in the way), is that perfect copy the same as its past predecessor ? If so, was it that we got back in time ?

If something sets the initial conditions of a local system (that may be as big as the observable universe for the sake of argument) so that instead of decreasing, the overall entropy decreases in that system (the number of initial states that do that are considerably less than the number of initial states where entropy will increase, but they exist), does that mean that this system is effectively going back in time ?

That was for some of my personal intuitions about it; to cut the long story short, I don't see time being a "dimension" as anything else than a useful mathematical trick. A formalism. You don't dig wormholes and speed one of the mouths at relativistic speeds if time as a dimension is just a mathematical trick.

Lately a new brand of physical theories that don't need time (for instance, Carlo Rovelli and Alain Connes version of quantum field theory); I find that it makes more sense that way, mind you, not an intuitive sense, but our intuitions about time might be as good and biased as our intuitions about how life was a fundamental property of matter, or how the sun seemed to orbit the earth. It makes more sense because it seems to be more parsimonious, and because it derives its results in part from thermodynamics and statistical effects like entropy, not from ad hoc dogma based on our own intuitions about time.

Edited by vyntager, 03 March 2008 - 07:45 PM.

[Luna]

In addition to what Vyntager already said,
As I see it by all logical ways, nothing that increases in a normal way can become infinite.
The energy to go faster than light is probably huge but not infinite, must be a misconception here.
As I'm not a physicists, someone else might be kind enough to look into it and post here is finding on the matter.

[Lazarus Long]

Infernity and a few others asked many (if not all) of these questions and more before and in order to not have to repeat all that analysis I suggest a review of this thread:

Why is light the fastest?

[nefastor]

Although AFAIK this doesn't relate to actual travel (as in manned space ships or teleportation), I thought I'd remind you guys of the Cerenkov effect.

Cerenkov radiation is this weird blueish glow you get in the water of pool-type nuclear reactors. It's due to particles traveling faster than light. The catch is, these particles are faster than the speed of light in water BUT still slower than 'c'.

Me, I really think we don't need FTL spaceships, even if we could build them. I'm more into teleportation because it seems much simpler to implement :

- A ship would need tremendous power to be able to fly faster than light. It'd be easier (and probably much safer) to generate that power on a planet.

- A ship must protect itself and its crew from both radiation and space debris. At FTL speed, I'd assume colliding with even a single atom of hydrogen would vaporize the entire ship (use the relativistic expression of the kinetic energy formula, not 1/2.m.v²)

The way I see it, we may never need to fly FTL : when we become immortal, we will have the time to send Stargate-esque hardware to distant stars using slower than light unmanned ships, so we can travel there instantly ourselves.

For what it's worth, teleportation research seems to be ahead of FTL propulsion, with quantum entanglement being used in many experiment.

Nefastor

[Luna]

Although AFAIK this doesn't relate to actual travel (as in manned space ships or teleportation), I thought I'd remind you guys of the Cerenkov effect.

Cerenkov radiation is this weird blueish glow you get in the water of pool-type nuclear reactors. It's due to particles traveling faster than light. The catch is, these particles are faster than the speed of light in water BUT still slower than 'c'.

Me, I really think we don't need FTL spaceships, even if we could build them. I'm more into teleportation because it seems much simpler to implement :

- A ship would need tremendous power to be able to fly faster than light. It'd be easier (and probably much safer) to generate that power on a planet.

- A ship must protect itself and its crew from both radiation and space debris. At FTL speed, I'd assume colliding with even a single atom of hydrogen would vaporize the entire ship (use the relativistic expression of the kinetic energy formula, not 1/2.m.v²)

The way I see it, we may never need to fly FTL : when we become immortal, we will have the time to send Stargate-esque hardware to distant stars using slower than light unmanned ships, so we can travel there instantly ourselves.

For what it's worth, teleportation research seems to be ahead of FTL propulsion, with quantum entanglement being used in many experiment.

Nefastor

Reminder, teleportation is a transfer of information.
In order for it to be far and fast you still need FTL comunication/travel.

[nefastor]

Reminder, teleportation is a transfer of information.
In order for it to be far and fast you still need FTL comunication/travel.

Quantum entanglement fits the bill. It is instantaneous (can't get any faster than that unless you arrive before you leave)

The problem with quantum entanglement, as I understand it, is that it naturally breaks when the entangled particles are too distant. Right now, "too distant" means 50 centimeters. But at least that's a start.

Nefastor

[chik]

Last year a guy called John Cramer obtained some funding from the public to start his time experiment.
http://seattlepi.nws..._timeguy12.html

[Luna]

I still believe quantum entanglment is going to be a big disappointment.
And I doubt it will do any good for human teleportation.