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Quantum Setback For Warp Drives
KentuckyFC writes "Warp drives were generally considered impossible by mainstream scientists until 1994 when the physicist Michael Alcubierre worked out how to build a faster-than-light drive using the principles of general relativity. His thinking was that while relativity prevents faster-than-light travel relative to the fabric of spacetime, it places no restriction on the speed at which regions of spacetime may move relative to each other. So a small bubble of spacetime containing a spacecraft could travel faster than the speed of light, at least in principle. But one unanswered question was what happens to the bubble when quantum mechanics is taken into account. Now, a team of physicists have worked it out, and it's bad news: the bubble becomes unstable at superluminal speeds, making warp drives impossible (probably)."
Or is it *both* Impossible and not Impossible?
is this where the improbability drive comes in?
yeah, someone had to say it.
The SCI-FI buff in me holds out hope that physics will uncover a trick to FTL, but...
It doesn't really matter if we cannot travel faster than the speed of light so long as we can live long enough to get there.
Who cares if it takes 50 years to fly to Alpha Centauri if we can engineer ourselves to live for a thousand!
This is my sig.
We all know what happens when you try to travel that fast!
Just do what the Planet Express Ship does and use a Dark Matter drive to move the Universe around us instead... :)
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From the article... "strongly implies that such a bubble would be unstable." Sounds like proof to me! Right. Just like it was proved impossible for planes to fly. It might indeed - eventually - prove to be impossible, or impossible to do meaningfully / reliably, but it's pretty unlikely we're in a position to make that call at this time. That's why we do research.
=cjs
So you mean to say my brand spanking new SSDs have become obsolete already???
Faster-than-light travel always causes causality paradoxes, so a priori, FTL drives are impossible unless special relativity is wrong. (That's is a bit like saying that perpetual motion machines are impossible unless thermodynamics is wrong.) The proposed mechanism behind the FTL drive doesn't matter -- it'll still cause a time paradox.
Just like we know any proposed perpetual motion machine must have a flaw, any proposed FTL drive must also have a flaw. They belong to the same class of impossible device, and deserve the same degree of consideration.
Back before helicopters were successfully demonstrated, people dismissed the idea, saying basically they violated the laws of physics, too...
Any warp engineer knows that.
Please note the submission date:
Semiclassical instability of dynamical warp drives
Heck, after 8 weeks of army basic training none of the 50 or so people in my company were strangers.
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This is best guess at the moment. We don't have a unified theory of everything proven and in the bank. We are not yet even sure how many dimensions the universe is constructed out of (the total varies between 4 and some large number every month). So it is an improbability with current physics knowledge versus a distinct impossibility (a small but significant difference in argument)
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That's it, cancel the Star Trek Movie. Now that I know it's all fake it just ruined it for me.
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Right. At about one G acceleration you can reach any point in the universe in a few years of ship time.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
Don't they remodulate the shield frequency (or reconfigure the emitter array), and that keeps the bubble stable just long enough?
I thought we knew that combining these two theories resulted in answers we know to be nonsense. So the implication is one or both of them are wrong in some way. So I'm a little confused why we should trust results based on the combination of two theories that don't work together.
Granted I'm just a laymen, but does anyone else want to comment about the intersection of these two theories?
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Quantum would be an atomically short distance...
IE: a "Quantum leap" is just an electron jumping to another valence level in an atom... it's not a very large distance =)
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In fact there is a fabric of sorts, see Casimir Effect for an experimental result of that "fabric".
It is not at all like the aether that people were thinking of in the 19th century, but it does exist. One way of looking at it is that the vacuum is filled with particles that are constantly popping in and out of existence. Another way is to look as the vacuum as having a "zero point" energy. Either way, it is not truly "empty".
It always works.
While what you say may be very true, the problem is that we have yet to come up with a more feasible method of reaching distant planets in a reasonable amount of time.
The next closest idea that Science and Science Fiction have come up with is Wormhole/Space Fold travel. And unless you have some safe way of generating more power than a large star in a safe and contained manner, that's going to be even tougher than FTL or Warp Bubble drive.
So our best bet is to spend the time doing a full scientific inquiry into FTL/WB drive including actually attempting to BUILD something and testing it. If after that we can show that FTL/WB drive is the cosmic equivalent of a perpetual motion machine, then OK. But let's do the hard Science and prove it first. IANAQP, but it seems to me that your theory and TFA theory are as about as likely as the Mexican guy's theory. Let's find out, shall we?
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That doesn't work. You can't transmit information faster than light; contrary to popular conception, quantum entanglement does not involve classical information transfer.
If you have one of a pair of dice, and the other is a thousand light-years away, one way to think of entanglement is to imagine that whatever number you roll is the number that shows up on the other die the next time it is rolled. Even if the two dice are linked, you can't control which number shows up, so you can't use the dice to communicate information.
I am completely hopeful for the sake of knowledge and experience that we get to into space like in Star Trek. However, I do note a bit of escapism in some of the hopes for a warp drive. I think people are a bit afraid of the idea that this Earth might be the only world humanity will ever live on. The cynic in me suggests that people want this world to be disposable.
We co-evolved with the planet all the way back to when we were microbes. This world is a part of us. Yes, let's try to break past the speed of light, for the sake of science and achievement. Are we existentially okay with our fate as a species being completely contained in this world? I think we can be.
No we don't, and no you couldn't. I suppose you're thinking of the EPR paradox? Very well. Let us say that I have a set of electrons in equal spin superpositions, and you, at some distant location, have their entangled counterparts. What's the protocol for communication?
Well, if I measure the spin of my electron 0 about the x axis, then in doing so I will also establish the spin of your electron 0 about that axis. The superposition on your electron has vanished without you touching it. Terrific, that's communication, right? I collapse your electrons in sequence, this one on the x axis, this one y, this one x, and so on, a binary code?
Well, no, it doesn't work like that. How can you tell if I've done anything at my end? By making measurements of your electrons? No - because that will collapse the superposition too. Let's say I measure electron 0's spin around the x axis to be positive. Immediately and instantaneously, faster than light across the universe, the superposition on your electron 0 collapses and I know it to be positive about the x axis.
But you don't know that. You might pick the y axis to measure, which is still a superposition. Or you might pick the x axis, and certainly you'll get a +, but you might have got that anyway. You can measure each electron only once - you change its state in doing so - so you can't do a series of tests, build up the statistics and find that on the y axis it's a 50/50 shot but on the x axis it's + every time. That's what you'd need to do in order to determine that I'd chosen the x axis. That's what you'd need in order to communicate faster than light. But since you only ever get one measurement, you get no information about what I did at the other end.
Real Daleks don't climb stairs - they level the building.
The only "somewhat" reliable theory we have so far that should work when both quantum and relativist thresholds are reached is the superstring theory (or it's advanced counter part or M-branes). Unfortunately nobody can tell if that theory is right or not since we don't have the means to measure any of the results that are predicted by that theory and are not in conformity with the general relativity or quantum physic.
Maybe with the LHC that with be possible, but that may not be the case. The maximum energy that LHC will be able to handle will in principle not be enough to put some of those principles in practice. BUT, perhaps we can observe a sub-"product" of superstring (M-brane) theory, the unfolding of extra spacial dimensions (6 or 11) and in that case, that should give us a pretty good idea that M-branes are the way to go.
Still, even if we don't see any of that with LHC, it doesn't mean the theory is wrong until we build a powerful enough particle accelerator that finally confirms or dismisses M-branes theory.
Sorry, but we already have faster-than-light communication trough quantum entanglement. The change in state happens instantly, without any delay, no matter what the distance is.
You're mis-interpreting quantum mechanics and entanglement. The second sentence in that quote is right, but it doesn't imply the first sentence, which is wrong.
When a quantum entanglement collapses, both of the entangled particles will end up in states that are strongly correlated, even if the two particles are very far apart. So yes you could have two entangled particles that are separated from each other, have them collapse, and there would be "instantaneous" correlations between them.
However this cannot be used for faster-than-light communication. (It makes for cool sci-fi, but isn't correct when you really look into the details of quantum mechanics.) The reason it cannot is because the collapse is (at least to the local observers) random. Neither side can predict nor influence* what random state their end of the entangled pair collapses into. So if we have two streams of entangled particles (one on Earth and one at Alpha Centauri), both sides would read out a random stream of answers (up/down, yes/no, 1/0 ... or whatever). Only once you compare the two streams do you realize that they were correlated more strongly than random chance (and classical mechanics) would allow. A cool experiment, to be sure! But it can't be used to transfer information.
Many people have tried to devise ways around the rules of quantum mechanics, to allow entanglement to be used for FTL communication. But all such proposals (to date) have been found to have mistakes with respect to our current understanding of quantum mechanics. To date, there is no loophole that allows one to circumvent the (local) randomness of quantum mechanics to allow FTL. Of course it's possible that modern relativity and quantum mechanics are both wrong. But at least for now there is no evidence of any information ever being transmitted faster-than-light.
* Actually you can try to influence the answers you get from your stream by selecting a particular measurement method. And while doing so does influence the states of the distant particles, your faraway friend won't know what sequence of measurements you selected. So he will select his own set of measurements, and end up with what seems like a random stream, and no way to correctly interpret what the stream "means" without knowing the sequence of measurements you performed. Of course the two sides can pre-arranged what measurement sequence to use, but that's not FTL communication... that just becomes old-fashioned communication. The point is that "communication" means "transfer of information", and one cannot transfer information via entanglement (which may be FTL), because one has to additionally transfer the measurement information in a sub-luminal way. This may sound "contrived" to prevent FTL communication, but that's just what our best equations currently describe.
The very people who should be aware how little they know compared to what is possible. They come up with these statements, and they forget that for every problem, there IS a solution, even if they can not figure it out themselves.
The question their current "findings" should be asking is "what makes it unstable?". They may not know, but that is the key to solving the problem.
People forget that scientists used to think that it was impossible to break the sound barrier for various reasons. Then they came up with the idea that the speed of light could not be broken. Time has proven again and again that the only thing stopping ANYTHING is not having the knowledge to do it. Not having knowledge does not make something impossible, it just means a CURRENT inability to do something.
First of all it's worth remembering that quantum mechanics and relativity are not 100% incompatible. In fact "relativistic quantum mechanics" has been around for a long time. Quantum theory was greatly advanced when relativistic effects were included.
But you're right that we have good reason to believe that something is wrong with either quantum mechanics or relativity (or both), since they give contradictory predictions in a certain number of extreme cases. (Quantum gravity is not yet solved...)
However we also have ample evidence that quantum mechanics and relativity are incredibly accurate and predictive theories in a vast range of circumstances. We have every reason to believe that the correct "Theory of Everything" will reduce to conventional quantum mechanics and conventional relativity in the appropriate limits. And thus we have every reason to continue using those theories to make predictions all over the place.
Now a warp bubble is one of those extreme situations where the two theories might be expected to give contradictory results, in which case only the hypothetical theory-of-everything would give the correct answers. But it is certainly still useful to ask what our current theories would predict for these extreme situations. It helps us better understand the theories. And, again, we have reasons to believe that many of the things our current theories predict (even in extreme situations) will be right. Absent the theory-of-everything, quantum mechanics + relativity will give us the "best guess" about how such objects would behave
My people are taught that it's a fluid, not a fabric. When particles pop into existance, or exist as matter, in our dimensional space their probability function becomes highly localized and creates a "void" between dimensions and a pressure density gradient at that point in space. This pressure forces the fluid of space to flow into these voids and it's this flow of space fluid that creates and explains the drag known to us as gravity.
We are also taught that if enough matter is brought together in a region of space the flow of space fluid into other dimensions becomes so strong that nothing, not even light, can escape the currents. We call these objects deep blue holes. Technically they are black because no light escapes, but we're smurfs and we think we're cool, so since cool blacks are bluish blacks we call them deep blue holes.
I'm pretty sure I got that explanation right. Brainy lectures on and on about it but it's hard to pay attention when the discussion is about deep blue holes... Smurfette sits next to me... droooooool....
I smurf everything and everything I smurf is perfect.
One of the nice things about the universe is that it's actually pretty hard to hide phenomenon. We, for instance, have been making no attempt to not blatantly broadcast our location and existence - while the sample size is small, do you really think any other civilization is going to have their first thought upon discovering radio waves be "Damn, better be careful about using lest an impossibly distant alien race finds out where we are!"?
No, far more likely is that if there is life out there, it's simply far enough away (or, correspondingly, too young) that we haven't had the chance to see any evidence of them. But to assume that 'if there is life, of course they see us', is entirely illogical.
[Ego]out
A 'failure' in science is an erroneous result. A valid negative result is still a scientific success (even if it's not as publishable).
Scientists point out problems, engineers fix them
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That's sounds like a circular argument:
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Arthur C. Clarke formulated the following three "laws" of prediction:
1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.
2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
3. Any sufficiently advanced technology is indistinguishable from magic.
(http://en.wikipedia.org/wiki/Clarke%27s_three_laws)
I assume then, a statement about superluminal travel being impossible, is actually good news.
6th Street Radio @ddombrowsky
Yeah it is funny hearing people say they have made a "quantum leap" which would mean "the smallest possible discreet leap". I mean even the show with that name wasn't implying huge leaps, so I don't know how it came to mean that in their heads. Or maybe they mean it's an advancement worthy of Scott Bakula?
I actually liked how the last Bond movie, "Quantum of Solace", used the term correctly. Though this probably confused some people. My roommate thought the name was stupid till I told him what "quantum" really meant and then he thought it was cool. :)
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People forget that scientists used to think that it was impossible to break the sound barrier for various reasons.
No they didn't. Some idiot writing for a news paper may have however.
If information wants to be free, why does my internet connection cost so much?
While I think achieving superluminous speeds may certainly be possible as our understanding of physics develops, it seems like it could be a moot point.
The idea for traveling large distances within the universe which involves folding space/time into a higher dimension seems both more efficient and generally better understood today. As was noted above, working with something like superluminous velocities is going to inevitably require analysis involving two of our most powerful models of physics, relativity and quantum mechanics, which at this point still don't play well with each other (at least not in every circumstance).
However, it seems like the general trend towards the theory of everything research continues to lean to higher dimensions as an accurate model. That being said, ideas that have been expressed that involve folding and or dropping out of the space/time continuum and reentering at a different location/configuration in the universe seems like it might still be a more viable option for traveling large distances.
Still though, superluminous speed does seem like it would be cool...
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Sustaining 1G for several years isn't magic. It's just advanced technology.
James Powell, the co-inventor of super-conducting maglev, described a mechanism to build a 1G rocket to travel to the stars. His basic idea was to use Mercury as a solar collector to manufacture a few tons of anti-matter. When you react the anti-matter, you get both power and ejectable mass moving at very high speed. A sci-fi author, Charles Pelligrino, wrote up the idea in the appendix to his book, Flying to Valhalla.
The Orion designers were thinking that once they got the first version working to ferry between the planets, they could build a star ship that would get to Alpha Centauri for $100 Billion in 1960 dollars. The cost was so far out of reach, the idea was almost forgotten.
The point is, you don't need magic to travel at 1G, you need resources.
You can only roll the dice once. After that they are no longer entangled.
So Joe carries 1000 particles, which have twins back home, to Joe's Space TV/VCR Repair Center, which is out near Betelgeuse. I want to send him a message: "Pound pastrami, can kraut, six bagels--bring home for Emma."
I "roll" particles to encode a 1 and leave 'em alone for 0. Sez I:
01010000 01101111 01110101 01101110 01100100 00100000 01110000 01100001 01110011 01110100 01110010 01100001 01101101 01101001 00101100 00100000 01100011 01100001 01101110 00100000 01101011 01110010 01100001 01110101 01110100 00101100 00100000 01110011 01101001 01111000 00100000 01100010 01100001 01100111 01100101 01101100 01110011 00101101 00101101 01100010 01110010 01101001 01101110 01100111 00100000 01101000 01101111 01101101 01100101 00100000 01100110 01101111 01110010 00100000 01000101 01101101 01101101 01100001 00101110
That doesn't work either because Joe doesn't know if you have rolled the dice or not.
Entangled particles are like dice that are already rolling, and they stop rolling the moment that either particle is observed.
So you and Joe each have a dice that, say, always roll the same number as each other. You look at your dice to cause it to stop rolling, and see that it rolled a 6. Joe can look at his dice too, and will also see a 6, but he doesn't know if he was the one that caused the dice to stop, or whether it was you who stopped it.
You both see a 6, but no actual information was transferred.
You are missing the point. All you can do is observe the particle, and thus learn something about the distant particle. You don't get to choose what you observe. You cant force the particle to have +y spin. You just observe it. The other observer would see the same thing as you, but that doesn't help you transmit data. It is like you are both looking at the same random set of data.
The entanglement usually occurs to conserve some physical quantity, such as spin or momentum. So for the dice example, let's say that every pair of entangled dice must add up to 7.
The problem is that they can only become entangled while they're still in luminal communication range - so you have to roll all the dice before the ship leaves.
If neither of you looks at your dice, then the number rolled remains undefined. As soon as one of you looks at a given die, both it and it's twin instantly take on their respective values (or you spawn 6 universes identical in every way except for the values rolled, if you like the multi-universe theory.) But when you look at a die, all you see is a number. You know that the number on the previously entangled die must be 7-#, but you have no way to tell whether you looked first or your counterpart on the ship.
Ask Franz Embacher and his team from the university of Vienna. They do exactly what I described and transferred information over half the city. I think he can control which number shows up.
Any sufficiently advanced intelligence is indistinguishable from stupidity.