WARP DRIVE, AHEM!

VTTFSH_V · 2005-09-13 17:28:01

In 1994, the theoretical physicist Miguel Alcubierre published a paper that introduces a method for a warp drive. Surprisingly, it has not made too much noise.

As we know, Einstein established that nothing can travel faster than the speed of light. That is a general statement. Nothing can LOCALLY travel faster than the speed of light.

Take for example the expansion of the early universe. Light was travelling at the speed of light, obviously, but spacetime itself was expanding too. Thus, an inertial observer, not effected by this expansion, would observe that the light is travelling faster that the speed of light.

Now we apply this concept to a warp drive. By distorting the spacetime around a vessel by making an expansion of spacetime behind a ship, and an opposite contraction of spacetime in front of the ship, the ship is "pushed" forward by spacetime itself. This is called a warp bubble. Since the spacetime INSIDE and OUTSIDE of the bubble is uneffected, no time dilation occurs. No effects of acceleration are felt in the ship since the ship is LOCALLY not moving.

There is no known way to induce this effect. Negative energy is needed, which can only come from exotic matter.

There must be a better to explain this spacetime stuff, so ask any questions that you may have.

GCNRevenger · 2005-09-13 18:57:14

Such a drive is basically taking your "point" in space, and instead of you moving through space to your destination, your local region of space is pulled to the destination.

"There is no known way to induce this effect. Negative energy is needed"

Which is why its fictional

Austin Stanley · 2005-09-14 03:35:49

Not supprisingly we have discussed this before to. The disscusion was here.

Even if we do some handwaving and create things such as "exotic matter" and "negative energy" it still does not overcome the fundemental problem with FTL in our relativistic universe, the problem of causality violation and pardox.

All FTL methods of communicaton/travel can cause the grandfather paradox when the situation is right.

An exert describing how and why.

"We can describe this effect by idealizing FTL to be "instantaneous", and describing how the more familar time dilation implies this effect. But remember, the same points apply to any FTL speed, you just have more messy arithmetic to grind through.

Consider a duel with tachyon pistols. Two duelists, A and B, are to stand back to back, then start out at 0.866 lightspeed for 8 seconds, turn, and fire. Tachyon pistol rounds move so fast, they are instantaneous for all practical purposes.

So, the duelists both set out --- at 0.866 lightspeed each relative to the other, so that the time dilation factor is 2 between them. Duelist A counts off 8 lightseconds, turns, and fires. Now, according to A (since in relativity all inertial frames are equally valid) B's the one who's moving, so B's clock is ticking at half-speed. Thus, the tachyon round hits B in the back as B's clock ticks 4 seconds.

Now B (according to relativity) has every right to consider A as moving, and thus, A is the one with the slowed clock. So, as B is hit in the back at tick 4, in outrage at A's firing before 8 seconds are up, B manages to turn and fire before being overcome by his fatal wound. And since in B's frame of reference it's A's clock that ticks slow, B's round hits A, striking A dead instantly, at A's second tick; a full six seconds before A fired the original round. A classic grandfather paradox.

Note, this is NOT a matter of when light gets to an observer, it is NOT an optical illusion. It is due to the fact that, in SR, the question of what occurs at the "same time as" something else is observer dependent.

As A fired that first shot at tick 8, the bullet effectively teleported from A's gun to B's back instantly --- instantly according to A. But for B, who was moving at 0.866 lightspeed WRT A, B was hit in the back by the bullet 4 seconds BEFORE the bullet was fired. And again note, this is NOT due to the optical illusion of lightspeed delay in viewing A's turn-and-shoot; the light form that event wouldn't reach B until MUCH later, not tick 4."

As you can see the problems with causality and simultaneity at a distance don't specificly lie with the FTL travel, but the rest of the universe. Any FTL situation could cause a grandfather paradox similar to the one above.

publiusr · 2005-09-14 12:34:31

About the best we can hope for (I hope you are not eating) would be Zubrin's Nuclear Salt Water Rocket and its 1g thrust.

The heating is going to be an issue--but it is a smoother ride than Orion.

GCNRevenger · 2005-09-14 12:50:04

Yeah, NSWR or GCNR in the short term, or high specific power VASIMR a little ways down the road.

How the Albicurie drive is supposed to work:

Think of space as a rope made of rubber, stretched between origin and destination, and you are an ant sitting on the origin end. Rather then walking along the rope from one end to the other, the maximum speed of which is the speed of light with all the messy relativity, there is another way... Instead, while the ant sits completly still on its spot of the rope, the rope is stretched so that the spot with the ant is now pulled until it is at/near the origin. You didn't have to walk a bit, the real "magic" is that the drive moves your point in space to the destination. That, in essence, is how its supposed to work.

publiusr · 2005-09-14 13:05:56

I think we'd have to have zero point to do that. I'm not holding my breath.

I'm more of a nuclear thermal advocate:

http://www.abo.fi/~mlindroo/Station/Slides/sld051t.htm
http://mysite.verizon.net/res0nnid/

Bimodal systems can supply electrical power as well.

GCNRevenger · 2005-09-14 13:49:47

The problem with solid core NTR is the maximum temperature the engine can achieve is not high enough to be a big improvement over chemical engines. Solid core NTR is better, and I think we may need it to get to Mars efficiently, but because of its limited temperature it doesn't really change the rules of the game.

The problem is not getting enough heat to raise the temperature, nuclear power sources are more then up to that task, the problem is that the reactor will simply melt at the tempertures needed to be a real paradeigm-shift in performance. Good, and better than chemical, but not lots better.

A GCNR or NSWR engine, on the other hand, have no such limitation. The GCNR engine intentionally melts and even vaporizes the nuclear fuel, and retains it inside the core within a vortex of liquid hydrogen and focused magnetic fields. The NSWR engine renders the fuel as a disolved salt solution, where the reaction doesn't occur until it is outside the ship behind the heat shield.

VASIMR engines might achieve similar or even higher specific impulse as well as a cosmic-ray deflecting magnetic field, plentiful excess electricity, and longer engine life. Unfortunatly, no power source has a high enough performance yet to operate such a beast.

In this case, I think it is a tossup between GCNR and NSWR. The former is probobly a little harder but would be safer and more conventional. The latter is different then anything before it, and the fuel would be "scarrier" to use.

reddragon · 2005-09-14 18:24:24

I think that the best option for something like a warp drive would be to establish a network of wormholes connecting distant places. Certainly we won't be doing this tomorrow, but eventually we may well find a way to create wormholes or find a way to use naturally occurring ones that may be found near black holes.

VTTFSH_T · 2005-09-14 20:50:15

Um... A warp drive has nothing to do with wormholes. Plus, opening wormholes may not be a good idea if we don't know what will happen if we do. What if they cause the universe were to dissapear because we opened one? Plus, are you going to fly near a black hole just to use the wormhole? How would you escape? What if the gravity of the black hole pulled you toward it instead of you getting to your wormhole? Worm holes shouldn't be played around with until we know what will happen if we open one.

VTTFSH_V · 2005-09-15 03:11:54

Furthermore, if we had the ability to induce a wormhole, then, by default, we would have the ability to create a warp bubble. They are both distortions of spacetime. Thus, using wormholes would be pointless because you would have to make SO many of them, concting every star, galaxy, etc. for it to compete with the convenience of a ship's personal warp drive. And with so many wormholes, the spacetime continuum would be so messed up, the potential cosmological disasters (for humans) would be incredible.

Austin Stanley · 2005-09-15 03:41:17

We can all be thankfull that special realtivity percludes such things then eh?

Also, what is the deal, are you to guys VTTFSH_V and VTTFSH_T diffrent people or what?

VTTFSH_V · 2005-09-15 04:08:19

We are friends, so yes, different people.

Did you mean "preclude" as in prevent? Even general relativity allows for a warp bubble.

I am going to post this once and for all! Everybody read it!

www.members.shaw.ca/mike.anderton/WarpDrive.pdf

mboeller · 2005-09-15 05:21:39

Hmmm..

The Alcubierre-WarpDrive is basically impossible. It's nothing more than a nice little mathematical idea without any real application.

If you are interested into warp-drives, hyper-drives or simple antigravity drives ( mass and/or inertia ) you have to look elsewhere.

IMHO the most promising ideas are the one's from Fran de Aquino and Burkhard Heim. Both have tried to unify quantum physics with relativity. Both have found new things. For example; with the theory from Heim it was possible to deduce the mass of all known particles directly from theory to within +- 1% or less ( AFAIR it was even more accurate, but the +-1% is already far better than any other theory since then ).

Fran de Aquino on the other side has an nice website about his theory which he has presented AFAIR at CERN and he has made successful trials to produce an antigravity-drive!

GCNRevenger · 2005-09-15 06:05:10

"he has made successful trials to produce an antigravity-drive!"

Yeah right, a proven anti-gravity device would make world headlines

Austin Stanley · 2005-09-15 07:11:06

I've read the paper before, and while it's a nice thought experiment, it doesn't change the cold hard facts of the real world.

#1. Information CANNOT be transmited FTL. Why? Because if it also causes some information to be transmited backwards in time to some observers, causing causality violations. Note that these observers are not necessarily limited to those actualy traveling FTL. Warp bubbles and what not cannot overcome this effect because it is an effect of the universe at large, not just some subset with a "bubble." Put bluntly any FTL travel causes the possibility for someobservers to recive a message before it was actualy sent. And I don't know about you, but in my universe CAUSE must always precced EFFECT. See my previous post for a worked out example.

#2. A warp drive must invoke "exotic matter" and "negative energy" in order to work. There is just one problem. These things do not exist. There is no theoretical support for their existance and absolutly no experimental or emperical evidence of their existance. Part of the problem here is applying mathmatical concepts to our real world. Once must remember that while math provides a great modle for our universe it is NOT our universe. Mathmatical constructs such as imaginary numbers, negative numbers, irrational numbers and so on simply do not exist in the physical universe where in the end everything must be finaly measured and counted somewhere. You can't give me -1 apples, and you find me a string sqrt(-1) inches long.

#3. Even if for some reason such a device was possible, the energy necessary to construct it would be huge! I have seen some estimations indicating it would need 10 times as much energy as present in the entire universe. So not only is the warp drive impossible it's inpracticle as well.

I realy don't know why I am bothering to reply to this junk anyways, I should just ignore you and turn my attention to serious discusions about Mars.

publiusr · 2005-09-16 13:00:37

I think it is a tossup between GCNR and NSWR. The former is probobly a little harder but would be safer and more conventional. The latter is different then anything before it, and the fuel would be "scarrier" to use.

The latter would be simpler. Fuel injection technology is about as simple as it gets--the starship equivalent of a diesel with glow-plugs.

karov · 2005-09-17 01:44:56

#1. Information CANNOT be transmited FTL. Why? Because if it also causes some information to be transmited backwards in time to some observers, causing causality violations. Note that these observers are not necessarily limited to those actualy traveling FTL. Warp bubbles and what not cannot overcome this effect because it is an effect of the universe at large, not just some subset with a "bubble." Put bluntly any FTL travel causes the possibility for someobservers to recive a message before it was actualy sent. And I don't know about you, but in my universe CAUSE must always precced EFFECT. See my previous post for a worked out example.
.

Don`t worry -- the acausality is the esence of the universe. It just comes out that in human mesoscale the world is causal and local .. in quantum sence it is not, in mega scale , too . This just comes to tell us somnething about the sence of the concept for scales. A "bubble" is a universe, no matter the size. Acausality of the FTL is not an argument against it. You can not judge about the Possibilia of fenomena, based on the ethical reflections about it. "Its imposible, cause is messy, and ugly, ah?"

There is experimental evidence of negative energy, and we know that for decades - the Casimir effect.

karov · 2005-09-17 01:57:11

And, Alqcubierre drive the WarpDrive WD ( respectivelly the van den Broek version, which doesn`t needs the energy of the whole Universe to run, but depends economically on the class of plankeons manageable) and the WormHoles WH, are difgferent effects based on one and a same thing -- that the space-time continuum has sence entirelly from its mass/eneregy content. Actually the continuum and the contained are one and a same essence. The continuum self-contaibns itself, thats why we have to work with universes - the continuums are closeds or infinite ( ther last is closed to but wit non-determined in maximum radius).. The same way one electron could be regarded as infinite universe consisting as ours of "equal" infinite balancing amounts of - and + energy, debalanced only in proportion of one e-mass in + direction, the bubbles of the WD or WH are ....

Remember the ideas of WH empires and imperial time, developing from the carting speed of the one of the WH mouths...

Now imagine WHs in quantum way reproduced in rate of 10exp100 in second and carted with WDs with practically infinite speed to the destinations.

Austin Stanley · 2005-09-17 04:43:40

To be honest I'm not sure I'm completely understanding all that you are trying to say but I'll reply to the points I understand.

#1. Causality not necessary.
I don't know how you can claim this, causality, the principle that things happen in response to things that cause them is absolutly vital to a logial understanding of the universe. Causality is litteraly the undminning of not just science and physics, but logic in general going all the way back to Aristotal. I'm not sure how you could have a any sort of ration system without it. I mean how can you analyse a universe in which the effects (the things that you measure) actualy create the cause. A universe in which the future creates the past? In any case it certianly does not match our emperical understanding of the universe.

#2. Casmir effect is negative energy.
Many people are confused by this, but it simply is not true. The Casimir effect is caused by presure diferentual of the virtual particle-anti-particle pairs bettwen two plates. The plates restrict the wavelengths of the virtual particles inbettwen them, allowing greater amounts of energy to be built up on the outside. This creats a pressure imbalance which creates the attractive force. Some have called this "negative energy" but it is not so.

karov · 2005-09-17 05:48:10

To be honest I'm not sure I'm completely understanding all that you are trying to say but I'll reply to the points I understand.
#1. Causality not necessary.
I don't know how you can claim this, causality, the principle that things happen in response to things that cause them is absolutly vital to a logial understanding of the universe. Causality is litteraly the undminning of not just science and physics, but logic in general going all the way back to Aristotal. I'm not sure how you could have a any sort of ration system without it. I mean how can you analyse a universe in which the effects (the things that you measure) actualy create the cause. A universe in which the future creates the past? In any case it certianly does not match our emperical understanding of the universe.
#2. Casmir effect is negative energy.
Many people are confused by this, but it simply is not true. The Casimir effect is caused by presure diferentual of the virtual particle-anti-particle pairs bettwen two plates. The plates restrict the wavelengths of the virtual particles inbettwen them, allowing greater amounts of energy to be built up on the outside. This creats a pressure imbalance which creates the attractive force. Some have called this "negative energy" but it is not so.

#1. Yes, you said everithing about the causality -- the causality is a construct of mind.

#2. What kind of particles-antiparticles. Virtual pairs consists of what?

karov · 2005-09-17 06:09:45

http://www.physics.hku.hk/~tboyce/sf/to … mhole.html

Dook · 2005-09-17 16:00:13

An object approaching the speed of light needs infinite energy to continue to increase speed.

What is the controlling physical law?

It's mass does not increase. How could it?

The universe is virtually empty of matter but full of electromagnetic radiation (EMR).

I've always wondered if maybe the objects own gravity field has something to do with it, like a supersonic aircraft that has trouble breaking the sound barrier because the sound wave builds up in front. Gravity is emitted at light speed so as you approach light speed the gravity can't escape and builds up in front like a wall.

GCNRevenger · 2005-09-17 16:04:49

That depends on what you call mass, Dook

The apparent mass does increase, that is, the inertia does indeed increase in a non-Newtonian fasion. Thanks to E=mc^2, matter and energy are not quite as distinct as you might think.

John Creighton · 2005-09-17 16:10:26

An object approaching the speed of light needs infinite energy to continue to increase speed.
What is the controlling physical law?
It's mass does not increase. How could it?
The universe is virtually empty of matter but full of electromagnetic radiation (EMR).
I've always wondered if maybe the objects own gravity field has something to do with it, like a supersonic aircraft that has trouble breaking the sound barrier because the sound wave builds up in front. Gravity is emitted at light speed so as you approach light speed the gravity can't escape and builds up in front like a wall.

It is an interesting thought. In general relativity there are gravitational waves and they have been used to explain the decay of orbit of a pulsar. Unfortunately no gravitational wave has ever been detected directly. Also gravitational waves are not needed to explain the ultimate speed limit under special relativity.

Dook · 2005-09-17 16:45:52

If it's true we should be able to detect gravity waves in front of large (planets), moving objects.

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#1 2005-09-13 17:28:01

Re: WARP DRIVE, AHEM!

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Re: WARP DRIVE, AHEM!

#3 2005-09-14 03:35:49

Re: WARP DRIVE, AHEM!

#4 2005-09-14 12:34:31

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#5 2005-09-14 12:50:04

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#6 2005-09-14 13:05:56

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#7 2005-09-14 13:49:47

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#8 2005-09-14 18:24:24

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#9 2005-09-14 20:50:15

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#10 2005-09-15 03:11:54

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#11 2005-09-15 03:41:17

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#12 2005-09-15 04:08:19

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#13 2005-09-15 05:21:39

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#14 2005-09-15 06:05:10

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#15 2005-09-15 07:11:06

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#16 2005-09-16 13:00:37

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#17 2005-09-17 01:44:56

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#18 2005-09-17 01:57:11

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#19 2005-09-17 04:43:40

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#20 2005-09-17 05:48:10

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#21 2005-09-17 06:09:45

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#22 2005-09-17 16:00:13

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#23 2005-09-17 16:04:49

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#24 2005-09-17 16:10:26

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#25 2005-09-17 16:45:52

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