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Warp Drive Breakthrough
NIck Porcino writes "Warp drive one step closer to reality!
From the abstract:
A spacetime is presented for which the total negative mass needed is only
the order of grams, accompanied by a negligible amoung of positive
energy. This constitutes a reduction of the absolute value of the energy
by 65 orders of magnitude. The new geometry satisfies the quantum
inequality concerning WEC [Weak Energy Condition] violations and exhibits
the same advantages as the original Alcubierre spacetime.
Read it here.
The two big problems to be resolved are 1) how do you get an object inside a warp bubble? 2) What happens to the object when the warp bubble collapses?
"
>1. Piezoelectric crystal can be made to expand
>and contract with another alternating current.
>The idea is, push on the capacitors when they
>have low mass, and pull on them when they have
>high mass. The resulting machine should be able
>to float in mid-air or even accelerate, if the
>amplitude of the effect can be made high enough.
I've actually seen a Discovery channel show about this. They were talking about some alternate propulsion schemes the military was looking at. They showed a film of this actually happenning. It was actually on a decent show too, not one of those "UFOs are real" type of shows.
OK, this is kind of bogus. Assume your frame of reference is indeed the solar system, and we measure time by, say, a radio broadcast giving the current time from earth. Warp 1000 light years away. Poof. We appear (by the ancient radio clock broadcasts, which are only just reaching our current position) to have already travelled back in time 1000 years. Whoosh, we rush back at near c. Doppler makes time in transit appear to speed up, with 1000 years elapsing in 'radio time' as we travel, even if our wristwatches tell us it took fifteen minutes. No time travel. (or, as a fop to those who use relativity to define time, "no time travel at the same spacial coordinates".)
If you're still puzzled, try thinking about putting the radio clock at the destination instead of the origin...
smoog
- Metal conducts electricity. Therefore, electromagnetic radiation at the surface of a piece of metal has zero electric field; otherwise the electrons in the metal would flow. (Of course if the frequency is high enough, the electrons can't keep up, and the metal becomes "transparent" to those fields. In other words, metal blocks radio waves, but is semi-transparent/semi-opaque to x-rays, and very transparent to gamma rays.
- A pair of parallel metal plates can have a standing wave electromagnetic field between them, much like pipe organs have standing air waves, or plucked guitar strings are a standing wave, and have a node at the bridge and the nut. When done with radio waves, you have what is commonly called "radar cavities", and indeed all of microwave & radar is based on this principle.
- Quantum space is filled with "zero-point" fluctuations in the electromagnetic field. These are basically electromagnetic waves that zip into existance for brief periods of time, and then cancel each other out again. When they occur between a pair of metal plates, these "unreal" quantum fluctions *must* have zero electric field on the metal plates, else the electrons would move.
- The pair of metal plates thus limit the types of virtual fields between them, resulting in a very weak attraction proportional to the distance between them taken to the fifth power. As someone mentioned, this effect was actually measured in th 1920's (?) and is almost simple enough to use a undergrad/grad school lab experiment.
- The theoretical interpretation is that the field between the plates has less than the average, i.e. less than zero amount of energy between them; i.e. since work=force x distance, and the force is attractive, the work (energy) must be negative.
So what do we have? We need to find a pair of very good conductors, made out of something much much smaller than atoms, and hold them a few hundred planck lengths apart from each other. The negative energy in between them should be enough to satisfy that needed in the theoretical paper.BTW, a planck length is *very* small -- 10^-43 meters if I remeber right. Like a few *zillion* times smaller than an atom.
I read something in Analog a few years back about
how running high frequency alternating current
through large capacitors causes their mass to
vary sinusoidally at about twice the frequency
of the current (and the amplitude of the
variations is proportional to the frequency).
(And I thought if you did this, the capacitor
would just get hot.)
I don't remember what this was called or who
discovered it; it has
something to do with Mach's Law. The effect
was supposed to have been observed, and
vanishingly small. But
1. Piezoelectric crystal can be made to expand
and contract with another alternating current.
The idea is, push on the capacitors when they
have low mass, and pull on them when they have
high mass. The resulting machine should be able
to float in mid-air or even accelerate, if the
amplitude of the effect can be made high enough.
2. The amplitude of the variation can (maybe) be
greater than the total mass of the capacitors,
leading to brief repeating periods of negative
mass. Don't think they last long enough to make
a very good warp drive, though...
Anybody care to burn up some capacitors and
test this?
--edkiser
First thing: If you want to read how traveling back in time to meet your former self might actually work, you MUST, *MUST* read "The Fabric of Reality" by by David Deutch.
He explains for the first time in any place, in a simple thought experiment, how such contradictions get resolved. He uses the language of recursive computing and turing machines, not physics, so you will be quite at home if you're are a CS major.
Secondly, FTL travel *doesn't* neccessarily lead to time travel.
As an example, I give you wormholes. Now, most people understand that all you have to do to cause wormholes to become time machines is accelerate one of the mouths until it has a different clock.
So for instance, let's say the entry point has a clock at 2pm, and the exit point has a clock of 1pm (because it is moving close to the speed of light and has a slower clock)
Now, if you bring those mouths of the wormhole within 30 minutes traveling distance of each other, you could enter the entrance at 2pm, arrive at the exit at 1pm, and fly back to the entrance and arrive at 1:30pm which is 30 minutes before you left. Then, you could stop yourself from going in.
However, there is a fundamental flaw in this argument. Matt Visser used relativistic quantum mechanics to prove that if you bring the mouths of the two wormholes close enough, virtual particles will form closed-timelike-loops *first*, the energy density of the space between the mouths will quickly diverge, and the wormholes will *close*
In other words, as soon as a closed-time-loop is close to being realized, radiation in the space diverges toward infinity rapidly, and the whole jumpgate collapses.
So, if we were talking about Babylon5 or StarTrek, there would be a fundamental law of the universe, which is wormholes can only be moved so close together. If you move them closer such that the travel time for light is less than the difference between their clocks, the wormholes will collapse.
Incidently, Hawking also proposed this, he called it the "Chronology Protection Conjecture", that the universe won't allow time loops to exist, and there would be an infinite radiation wall to travel through in any such loop.
There are many such theorems in physics, such as the "naked singularity" rule for black holes. Can a singularity exist without an event horizon, such that the rest of the universe could view it?
Probably not.
In quantum tunnelling, the tunnelling particle has been considered to have negative energy, as it enters a region it doesnt have sufficent energy to enter (classically)
Some theorists postulate that it has "borrowed" energy from its surroundings, and has an energy debt, so has negative energy.
Putting negative energy into e=mc**2 gives interesting results for the mass, obviously.
The article was very interesting, but I dont think its been refereed yet, so I wouldnt get excited yet. It seems to rely on "Alcubierre Space" (which I've not seen defined) being either wrong, or adjustable. As its raining, and I should be revising for an exam tomorrow, I dont want to chase up references!
If, as is stated in the paper, microscopic warp bubbles are possible, would it not be possible to have a "warp foam", ie: a huge number of warp bubbles, and have them move together, that would avoid the size problem.
-Yarn - Rio Karma: Excellent
Anonymous Coward wrote:
...use one of these guys to put an olympic sized swimming pool in my closet. The author seems to indicate that the warp bubble is larger on the inside than on the outside.
...implement that inertial damping drive system I've been kicking around.
...avoid speeding tickets on I75 by travelling in a microscopically small bubble of space.
Sure, it would just take many years of research to engineer the closet, and millions of dollars to build the closet. Oh, and if you try to enter the closet to use the pool, your body will be destroyed by tidal forces.
You don't need inertial damping with a warp drive. The warp bubble moves, the vehicle stands still.
I don't think the highway would be all that happy with a Warp Bubble travelling down it, but I don't think the state troopers have warp detectors yet.
----
Open mind, insert foot.
This paper is part of the ongoing abstract research into the possibility of travelling faster than light without breaking the laws of relativity. There are two leading proposals, usually referred in laymans terms as "Warp Drives" and "Wormholes".
The Warp Drive idea was first formalized (i.e. given all the math to show it should work, given sufficient engineering prowess) by M. Alcubierre, so it is sometimes called the Alcubierre Warp Drive. It has three big drawbacks: it requires an absurd amount of exotic energy and matter (some of which we don't yet know how to make), you can't see anything while Warping, and there is no theory on how to stop. This paper addresses the first problem, with the equations given, you need far less exotic energy and matter.
For some excellent laymans info on Faster Than Light issues, check out NASA's Warp Drive, When? site.
----
Open mind, insert foot.
Despite what the blurb implies, this is all still very theoretical stuff. Don't expect to see warp drives in actual use in your lifetime.
Reading through the paper (which it WAY over my head) it sounds like the researcher found a much more efficent way to travel once we figure out how to fold space-time (with negative energy I guess).
Of course only a few years ago (like 70 or so) I'd be saying the same thing about general purpose personal computers...
I read the internet for the articles.
Could somebody explain this bit of science news in a way I could understand? Thanks!
-- You can actually change my mind with a good argument.
Could someone summarize the article in laymans' terms, please? :)
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What is your Slash Rating?
Have I missed something, or is negative mass and negative energy still in the "pure speculation" state -- the equations allow for it, and from a symmetry point of view it seems plausible, but last I heard we have no evidence for its existance, no theoretical way to produce any, etc.?
(Note: Negative mass is not anti-matter. Anti-matter has positive mass, and opposite charge/spin/other properties of "normal" matter. Matter plus anti-matter equals energy (which manifests as other postive-mass particles). Matter plus negative matter should equal nothing, zero, zip.)
Mashed potatoes can be your friends!
The problem is the mass increase. As you accelerate to the speed of light, you gain kinetic energy (naturally). We know that energy has mass. Solving the system of equasions (left as an exercise), we find that as v approaches c, mass approaches infinity. Thus, it takes an infinite amount of energy to actually reach lightspeed for ordinary matter (tachyons are another thing entirly).
So far, experimental evidence has matched the predicted values very nicely.
Mabey you can't go faster then the speed of light. (But that's assuming we understand that part of physics.. which is still in much debate) But by the same token you can "FOLD" space time. (IE wormhole). This would alow you to travel large distances in very little time. Your velocity would be well below lightspeed.. but the distance would have "folded" from light-years.. to light-minutes.
Now if someone came up with a device that could fold space directly infront of a space ship.. you could effectively travel faster then light..
What happened to the other problems with FTL travel?
I'm thinking specifically here about the more slippery definition of "simultaneous" in special relativity, and it's consequences. Assume a ship that can:
a. Accelerate to any sublight speed (and thus any "normal" reference frame) arbitrarily fast.
b. Use "Warp Drive" to move between two points in space time faster than light.
That's all you need, and assumption a. is perfectly in accordance with physical laws (and technically plausible with some externally powered propulsion system).
Throw in the cute fact that for any two points in spacetime that are not in each other's light cones, there is an inertial frame of reference where those two points are simultaneous, and your ship can:
1. Warp 1000 light years away, simultaneous with the frame of reference of the solar system.
2. Accelerate to near light speed.
3. Warp back to earth, but 999 years before it left.
I wish I could link in a diagram of this... but go look in a physics textbook; it's a classic paradox meant to show why FTL travel is impossible.
I've never heard a good explanation of how Alcubierre's theory (not to mention whatever new concept has come up) deals with this.
Yes, causality would be preserved using a warp drive since nothing is travelling faster than light. Warp drive does not increase your velocity, it decreases the distance you must travel.
A better way to appreciate things is to look back 100 yrs. At the last turn of the century, the physics community was astounded by some amazing new discoveries. What were these mysterious X-rays? And did you read about radioactivity? I wonder if something besides uranium was radioactive? And electrons! If these things had a negative charge, there just has to be something in the atom with a positive charge. Finally, I just know that someday, man will truly fly through the air.
Moral: Who knows what the future may bring.
An interesting variation on FTL information transfer (not to mention a serious slam of the Copenhagen Interpretation) can be found here.
You will not drink with us, but you would taste our steel? - Walter Matthau, The Pirates
True, but if I'm reading this right the area inside the walls can be significantly larger. Region I in the diagram is a 'pocket which has a large inner metric diameter.' he also states in the abstract that his solution supports the 'transport of macroscopic objects.'
In the ever popular rubber sheet model, it seems he has a large inflated balloon where the lips comprise the warp bubble. Except that the space inside the bubble is also locally flat.
In other words, what he has is not just a warp drive, but also a TARDIS....
I forget who told me this, once upon a time... "once its been proven on paper, it becomes merely an engineering problem".
More corporations need to get together and start investing millions into independent research labs, where they're NOT expected to produce results immediately. Raw science, more research into highly advanced projects. Wonderful stuff can happen. We could see a working warp drive in our lifetimes, given the time and resources.
Of course, I'm taking the "how things should be" view again, rather than "how things are"... keeps me from getting depressed, though.
Actually, no. If only electrons and positrons and photons existed, then you might be able to draw a Feynman diagram with one line representing all electrons and protons, but beta decay takes care of that. A quark can decay into another quark, an electron, and an antineutrino. This provides the start of a new electron line. Similarly, a quark can decay into a positron, another quark, and a neutrino. This provides the end of an electron line. In principle, the reverse reactions could occur as well.
Actually, that's not accurate, if I understand correctly. As the universe contracts, GPE will certainly become more negative, but as a result of this kinetic energy goes _up_ for everything that's contracting. Thus, the universe gets hotter again.
(1) Objects far apart have more energy than objects close together (because it takes energy to separate them)
(2) The universe is expanding.
This just is just a statement that the total kinetic and rest energy of the objects in the universe has the same magnitude as the total gravitational potential energy of all objects in the universe. This is actually what _causes_ the universe to heat up as it contracts (and cool as it expands; the microwave background is a good example of this).
As an aside, the jury is still out as to whether the universe is really flat or not (i.e. whether or not this relation holds). We usually assume so because it answers a lot of questions, but we're having a hard time proving it.
2. Accelerate to near light speed.
3. Warp back to earth, but 999 years before it left.
You could indeed do this with a faster-than-light drive. Where's the problem
The question then becomes, what are the physical consequences of time travel, and does this always result in contradictions? This will either rule out or severely limit what can be done with time travel, and by extension FTL drives.
You run into similar questions with tachyons.
It just ain't possible.
Not strictly true. All that your example shows is that you would not be able to kill your former self. Two of the several solutions that I've heard postulated are:
Under this system, you would certainly not be able to kill yourself, becuase you didn't (you survived to travel backwards in time, didn't you?). This physically corresponds to limiting (drastically) the number of possible events that can occur within a loop of spacetime that folds back on itself in the time direction. This in turn means that such loops are entropically very unfavourable, but they could still in principle occur if a greater increase in entropy happened elsewhere.
This refers to the "multiple histories" interpretation of quantum dynamics. Under this system, when you flip a coin, it lands on both sides - just in different universes. What actually happens is that all possible ways for a probability waveform to collapse happen, in different universes. If you travel back in time, you arrive in another universe, that looks a lot like the one you remember from that time - but in which a time traveller spontaneously appeared and killed the person who would have been you in your universe. This system doesn't impose entropic limits, but how exactly you travel between parallel universes is left as an exercise.
Both of these systems avoid the paradox that you menion.
Everyone who is concerned with creating a paradox by going back in time to kill themselves thus preventing themselves from doing so and creating a paradox is forgetting one little detail, our universe has an infinite number of facets. Quantum physisists have found that this is indeed true, the only way to determine the characteristics of a particle is to look at it. While this sounds like something you might take for greanted it isn't. Shrodingers (sp?) cat is the most often used example. The properties anything are undeterminable until viewed from an outside point of reference. This can apply not only to particle physics but to dimensional physics. For every moment there is an infinite number of possibilities for that moment for every point in the universe, and you only see one set of facets every moment. imagine points in the universe like coins. Spin them on their sides and let them all land, when they all land, face up or down that is a single moment, now repeat this process with an infinite number of coins with an infinite number of sides to understand what I'm getting at. Therefore you can only create a paradox in so many parallel instances. And therefore not create a true paradox, only one thats limited by the number of instances you actually go back in time and kill yourself.
As to faster than light travel, you would not go back in time unless you actually accelerated near the speed of light, the whole theory of FTL travel is never actually reaching the speed of light, just sidestepping part of the distance between your point of origin and your destination. Which needs no "inertia dampeners" or the like, just a warp feild generator (I say that like you can pick one up at Pep Boys).
I'm a loner Dottie, a Rebel.
> 1) how do you get an object inside a warp bubble?
Two words: Klein Bottle.
Now If I could only find the fine Irish Whisky I poured in there.
I have discovered a truly marvelous sig, unfortunately the sig limit is too small to contain i
Well, there's Woodward's work. Basically, as a result of Mach's principle, it predicts a transient mass fluctuation in an LRC circuit.
It could be the "impulse engine" of ST fame, or the hover cars off the Jetsons...
(Just maybe, it could also provide a large enough mass fluctuation for more exotic uses, like temporary wormhole stabilisation...)
NB. IANAP (I am not a Physicist (...and boy, does it show...))
Woodward carried out a test, which seemed to confirm the theory. However, an unforseen non-linear response in some of the experimental equipment casts doubt on the first results. Even if the fluctuations were a couple of orders of magnitude smaller than observed, it would still be a major breakthrough. NASA seems to think so too, and are, AFAIK, quietly working on a repeat test in their breakthrough propulsion labs...
Anyway, the theory makes interesting reading.
Here's the relevant links:
chaos.fullerton.edu/Woodward.html
www.inetarena.com/~noetic/pls/wo odward.html
Choice of masters is not freedom.
Actually, you're wrong on both counts.
1) You _can_ go faster than the speed of light, just not directly. You can't just turn the engines of a spaceship on "high," you have to skip over some of the space you're travelling through, and your _effective_ speed jumps past the speed of light. Both wormholes and "spacefolding" technologies - both of which are theoretically proven - would enable one to do this.
2) Yes, you can. In fact, we know how to do it today. The problem is, it takes an astronomically large amount of energy. It requires a wormhole in order to achieve it. You take one end of the wormhole and take it on a tour of the solar system at _relativistic_ speeds. You keep the other one stationary. Due to the time dilation, time passes for one a lot slower than it does for the other. Since one end of the wormhole has experienced less passage of time than the other, one end resides in the past, and one resides in the future. Then you can freely travel backwards and fowards through time via the wormhole.
There are other ways to travel backwards and forwards through time, but most are terribly implausible (e.g., infinitely long rotating cylinders spinning at relativistic speeds - I don't understand the full complexities of that particular process). And all have been discovered as parts of solutions to Einstein's equations, which have very little to do with quantum theory. So even assuming only relativity applies, you're still hosed.
The method, as the author himself points out, does have quite a few problems, though. First off, it's a microscopic bubble. He says that the walls can initially be only a few hundred Planck's lengths thick at the start. And as you slow it down, the "warp bubble" will expand, thus making the walls thinner until they actually shrink to lenghts less than Planck's constant, which would cause unpredictable results to say the least.
Also, the authors says that though this is orders of magnitudes less energy, it still requires "unreasonably large energy densities."
And, as another comment said, negative energy isn't exactly something that you can just buy at Amoco, and until a method to easily create it is developed, none of this is realistic.
Still, this is damn cool to say the least. I can't wait to get to work in seconds. And this could possibly do wonders for communication. A superluminal link would be just a little bit faster than my Ethernet connection, I'd guess :)
-- atomly
Perhaps that is a "law" of backward time travel..if I go back and attampt to kill myself, I won't be able to, since that will prevent my trip in the first place, which means I won't die, which means I'll live to travel back in time. This only means I can't cause my own death somehow since that would violate causality, not that if it were physically possible that I couldn't travel back in time(maybe killing myself would automatically "self correct" and the knife I stabbed my younger self with would have no effect).
A more likely scenario is that, as may be postulated by Hiesenberg followers, that every possible past and future state exists in parallel. Going back in time and killing an earlier me only disrupts one possible time line, not the one from which I originated (Sliders!). This fits very well with Quantum theory and violates no tenet of relativity.
Have some imagination. Orville Wright once said that man (sic) would not fly in his lifetime. Try to think outside the box instead of dismissing ideas outright because they don't agree with your world view.
Never by hatred has hatred been appeased, only by kindness - the Buddha
Mind you, my physics and cosmology is ~15 years out of date, but as I recall, the net energy of the universe as a whole is a positive number, which (theoretically) can be tapped. As a practice, the number was re-set to zero, but if we're already warping space-time to produce a bubble that moves across it at speeds faster than that which matter can transit, the stressed space-time would likely make it easier to tap the so-called Vacuum Energy, and thus maintain and propagate the bubble. . . .
If my physics IS outdated, then ignore this, but I recall Dr. Charles Sheffield, NASA physicist and SF author discussing tapping vacuum energy as little as 2 years ago, so this MAY be a viable approach, assuming energy density is sufficient for the application.
Getting the negative mass is, alas, an area where my ignorance is sufficient to even guestimate an answer. . .
>The two big problems to be resolved are
Already well understood:
> 1) how do you get an object inside a warp bubble?
Wander into Main Engineering while your genius son is tinkering with the engines.
> 2) What happens to the object when the warp bubble collapses?
People start disappearing and nobody remembers that they ever existed.
(For the humor-impaired: ST:TNG "Remember Me")
The energy that would be required for warp travel is irrelevent; energy is abundant at this time in the universe. (And worse come to worst, we sacrifice some matter.) Much of the physics we are dealing with is not conventional, and we will soon see a new relevation to change the entire perspective on the reality surrounding us. Warp drives, so cliche as that may be, can exist. Indeed, it is likely that they do. Just to throw you for a loop, it is possible and even probable that the entire universe is composed of a single electron in a parallel time frame for each instance (near infinite). Interesting, no? I say this because a positron, the electron's positive energitic counterpart, is mathematically described as an electron travelling back in time (i.e. negative time). Still, much work is to be done on this yet. The reality constraining us is not what it used to be. We should not forget what we have overcome, lest we fail to overcome the barriers before us now.
Not only is faster than light travel possible, but I believe it has been demonstrated.
:)
Information travels faster than light. (because information doesn't actually travel, for a normal definition of that word) Would someone with a heavier physics background please correct me here? I'm pulling this from memory:
Two particles can be bonded such that their collective spin state is always 0. knowledge (or lack thereof) of a particle's spin state is information. once these particles are bonded, the space seperating them is irrelevant. they can be next to each other or on opposite ends of the universe, and as soon as you change (observe) the spin state of one, the spin state of the other *instantly* becomes defined. the information travels without actually entering the space seperating the particles, which means that it isn't subject to the usual limitations placed on physical objects (namely a ~186,202 miles/sec speed limit).
i'm not sure how modern physics handles this. i believe einstein rejected it, but i think it's actually been experimentally confirmed in the past several years. you could incorporate yet another dimension into your conception of existance (5? 6? n?).
the curious part is how closely this resembles what mystics have been saying for millenia: space is an illusion.
another curious side effect of this is that the speed of light (in very much simplified laymans terms) seperates the "past" from the "future" and keeps them both out of the ever-present "present" (be here now). if you allow for faster than light travel, the chain of causality as we know it must be abandoned. the past and the future get all mixed up, and you have cause following effect etc.
i will cease my rambling now and get back to work
"I think any time you expose vulnerabilities it's a good thing." -Attorney General Janet Reno
If I enter a time machine in 1999, go back to 1979, then kill the "other me" in 1989, then the "paradox" is that I cannot exist in time 1999 to do these things.
To an observer alive during all this time, they will see one of me until 1979, then sees my evil twin materialize for some unknown reason in 1979. Between 1979 and 1989, the observer sees both myself and "my evil twin" (who is actually myself, but may as well not be). After time 1989, the non-time-traveling me is in a pine box, while the evil twin is walking around.
From this observer's perspective, nothing of particular importance occurs in 1999. Nobody enters the time machine. The fact that my evil twin remembers a particular event in 1999 is irrelevant. It is irrelevant because 1999 is no longer what we think.
To those of us unfamiliar with time travel (I'll assume that's all of us, save the Gallifreyan contingent), 1999 is a fixed series of events. Or at least, the first five months of it is a fixed series of events--we don't remember the other seven months, because "they haven't happened yet". We have a one-to-one correlation between personal time and wall time. That is, we've already experienced "April 1999", and never expect to experience it again.
To my "evil twin", what we call "April 1999" has a many-to-one correlation with his own memory. He can go through April as many times as you can walk through a revolving door.
To the third-party observer, time travel didn't happen. Somebody shows up out of nowhere in 1979 (surely weird, but no paradox). He kills someone who looks like him in 1989, and lives past 1999 and well into the next century. No time travel, no paradox.
So who sees the paradox? The time traveler sees no paradox. Non-time-travelers see no paradox. The only way to see a paradox here is to exist outside of time. The only one I know like that is God Himself, and I don't think that He will get thrown by somebody dinking with a knife and a time machine.
Remember the Bart Simpson correlary to Shrodinger's Cat: "I didn't do it, nobody saw me do it, you can't prove anything". Since nobody can get both the precice position and the precice velocity of a particle, it is arguable that they do not exist. If no observer can record the phenomenon, it didn't happen. Since nobody can witness the paradox, it doesn't exist.
Note: I was kidding about the hallucinogens. If you need to stretch your mind in those sorts of directions, just stay away for four days straight. It works for me ;^>
--The basis of all love is respect
Well then, it's a logical impossibility for you to go back and create a logical contradiction. Let's say I go back in time and try to kill off a previous self. The simplest break to this paradox is for me to fail. (Possibly through bizzare coincidence leading to the discovery of a way to time travel, if you're feeling ironic.)
Basically, anything you go back in time and do, has already been done. You can't edit the future, but you can certainly cause it.
At least, that's how I view it. This is leaning towards Philosophy, not Physics, and only one of those is my major.
Uh... that was not a troll. I was quite serious, actually. I guess admitting a lack of space/time theory knowledge isn't popular? Oh well. No biggie...
DDuck
Of course, your speed will depend on the observer, just because it is defined relative to the observer. But the physics (i.e. what actually happens) is independent of the observer. In your example of a tree and an observer falling in the woods, the observer would certainly see that the tree is stationary, but the ground would seem to be travelling at a very disconcerting speed!
*sigh* Every time anyone mentions time travel some well-meaning idiot feels the need to mention the old "What if I went back in time and killed my former self?" cliche. Since you were able to type this stupid, overworked, meaningless waste of bandwidth, I will personally assure you that, should you go back in time and kill your former self at some point in the future, you will elect to perform this service to humanity at such a time as to preserve this winning example of the journalist's art.
DoktorMel@yahoo.com
-- The Sage does nothing, and nothing is left undone. --Lao Tzu
The problem is that the two states are highly *correlated*, but you can't actually get any data without communication between the points (i.e. each side will get a random stream of data, but if they compare their data, they can see when it was correlated, and therefore whether spin coupling had happened at that point). Since you need to transmit some data in order to tell, this doesn't let you transfer information faster than c.
Okay, i'm no physics major.. but i try to keep current and have read enough to consider myself at the very least a knowledgable layman (yeah, i know the whole thing about a little knowledge being dangerous) and i cant say that i understand why exactly FTL travel is so impossible. I mean, why is 300,000km/s such a fundamental barrier? Okay, objects travelling anywhere near that velocity do behave oddly as we view them.. but who says that's so important? so the math says objects shouldnt exceed that speed without doing x y and z.. 100 years ago the math said a whole lot of things we know are patently false. *cough cough ether cough cough*
Now here's my take on it: relativity says that we cant exceed X m/s without having the rate we move through time change. So then in order to calculate exactly how fast you're moving, you have to do one of two things: calculate your base movement rate from an exact zero state an include your movement across the planetary surface, the revolutionary speed of the planet, speed of planet around the sun, speed of sun around galactic core, speed of galaxy in direction X (not to mention possible rotation of galaxy around unknown object(s) etc) or, the approach normally taken: ignore it. So far as i can tell from what i've read, relativity uses observer-based velocity. If your REAL velocity is 290,000km/s but the guy watching you sees you travel at 60 km/h.. according to relativity, you're doing 60 km/h. Now perhaps it's just me.. but this seems just a little silly. Why should who's watching alter everything? It's like the old 'if a tree falls in the woods and nobody's around, does it make a sound?' the obvious answer being 'yes'. Afterall, falling trees always make noise.. why would they stop? So then according to relativity, if a tree falls in the woods, and the only person around is falling too, it doesnt make a sound because, at the perspective of the observer, the tree never fell over. *shrug* i can understand collapsing waveforms and the uncertainty principle, but observer-based math just doesnt make any sense to me.
Dreamweaver
"If a man hasn't discovered something he will die for, he isn't fit to live" -- MLK, Jr.
Keep in mind that xxx.lanl.gov (where the paper is posted) is not a refereed journal. This paper
may not have been subjected to any peer review, so it's contents should be taken accordingly. Many times serious corrections or withdrawals are made to this pre-print archive. It would probably be better to not publicize something like this until it has been read be many specialists.
jabber: johnynek@jabber.org
The current issue of Scientific American has an article on Kurt Godel. Although most of his important contributions were in mathematical logic and theorem proving, he also did some work on relativity and spent a lot of time talking to Einstein. One of his contributions to relativity was a mathematical proof that time travel is not inconsistent with Einstein's theories of relativity. It might be inconsistent with something else we don't know about (or perhaps with something we've learned since then?), but it seems like we should keep our minds open.
What's more, even if the universe is somehow (from what little I know about quantum, I just don't see how) completely causal and logical, that doesn't necessarily make it any less mysterious. Formal logic has been shown to have some startling limitations. Kurt Godel's Incompleteness Theorem demonstrates beyond any doubt that there are True statements, in any sufficiently powerful logical system, which are unprovable. This essentially means that logic can be "undecidable" in some cases. There's nothing that says the universe itself can't have logic/consistency/decidability problems itself.
BTW, I'm not just trying to be argumentative here. Locality of causality and logic is all a very real possibility. Just ask a serious physicist.
Would we have to sacrifice relativity for a fixed frame to measure FTL? One could certainly model an infinite n-dimensional system, whereby within any given dimension all measurements were relative to its cohabitants. A unified relative constant could exist for each frame and only become non-essential based upon the knowledge or a more precise fixed frame (the next layer out).
Thus, any set of relative measures would still apply as long as you remained within a single dimension. The knowledge of the (next) absolute frame of reference would only make it Easier to develop physical law. It would not eliminate the system based upon relative physical law.
Maybe that's a little more mathematics oriented than physics; however, I would be interested in any thoughts.