[ARCHIVED THREAD] - Physics buffs - Need help (Page 1 of 2)
Posted: 3/7/2005 4:03:32 PM EDT
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I have done much Googling, and to haven't found my answer. I know the debate of faster than light travel (and it's possibilities and impropabilities) often comes up... BUT WHAT ABOUT FASTER THAN LIGHT COMMUNICATIONS?! Exactly, HOW, would a spaceship travelling faster than light transmit a signal? Would it just resort to using slow (relative to the spaceship) travelling radiowaves that can't even match speed with the spaceship? Exactly what, and how, is the most promising faster than light communication alternative? I've heard something about optical microwaves, but how exactly could that be FASTER than light? |
Ok, doesn't travel faster than light, but arrives faster than light. My question still stands. |
Why the hell are you worried about communicating when you reach the speed of light. I would be worried about reaching the speed of light first. Which begs the question. What would happen 'if' we could build a giant merry-go-around in space and keep keep speeding it up? If one makes it big enough and spins it fast enough surely the tagential velocity would exceed the speed of light. Then what would happen to the end of the merry-go-around. |
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Apparently you can send info faster than the speed of light......4x's faster to be exact www.newscientist.com/article.ns?id=dn2796 Edited: Should have read the whole article, "While the peak moves faster than light speed, the total energy of the pulse does not. This means Einstein's relativity is preserved, so do not expect super-fast starships or time machines anytime soon. Signals also get weaker and more distorted the faster they go, so in theory no useful information can get transmitted at faster-than-light speeds, though Robertson hopes his students and others can now rigorously and cheaply test those ideas. " |
Thank you, this was along the lines of what I was wondering. |
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You need to become intimately familiar with the concept of frames of reference. The ability of a spacecraft travelling at speeds approaching C would become somewhat of a moot point due to time dilation. From the frame of reference fixated on the spacecraft, your radio waves would propagate out at the speed of light in all directions. From the frame of reference of a "stationary" observer, the radio waves would propagate at the speed of light in all directions from the spacefract, but would be redshifted or blueshifted (depending on your position relative to the craft). Wrapping your frontal lobes around relativistic physics is not a simple matter. I recommend that you read some of the more popularized physics accounts, such as Einstein's work "Relativity" or any of the less-mathematical treatments available at bookstores. Jim |
| Actually, a communications system can be developed with infinite speed. The pioneer of this technology was the mathematical genius who was also the guitarist with the band Iron Butterfly, who died under mysterious circumstances. It depends on a quantum physics phenomenon called Entanglement. Particles and antiparticles are created at the same time, with opposite spin. The spin is indeterminate until one of the particles is observed - the antiparticle, no matter where it is in the universe, will then have the opposite spin. How they communicate this information is above me, and the mathematics behind it is very advanced, but the phenomenon has been duplicated in labs. Using this system, you can establish a binary communcations system with infinite speed. |
Supply and demand I guess. I won't need you magical radio till my car goes the speed of light. And when that happens I sure as shit aint' gonna answer my cell phone at that speed. |
It's not really a useful technique for signaling, nor is it likely to be (though who knows where it may lead). There is a specific term for that phenomenon (the peak of the wave travelling faster than the bulk of the wave) but it is escaping me at the moment. Jim |
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Physics be hard stuff, yo. Basically, just be aware that the theories that are popular today most likely aren't the be-all-end-all of physics. Years from now, some guy will come up with a theory that explains things better or some new data will emerge that will refine what is currently out there. |
the speed of light is constant in all reference frames. so it would move at the speed of light. |
There are inherent limitations to that type of signal. It is not yet certain that you can create a useful communications system using this characteristic. Jim |
If they DO get this system to work, there is not limitation to the speed with which the devices can communicate with each other. One box could be in the Milky Way galaxy, the other in the Andromeda galaxy, and the communication would be as instantaneous as two walky-talkies 100 yards apart. |
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Here is a good article explaining it in elementary terms, along with applications of Quantum Entanglement www.joot.com/dave/writings/articles/entanglement/ 9. Applications Quantum Computers Anything a classical computer can do, a quantum computer can do equally well, or better. In some cases, such as factoring large numbers, a quantum computer can work orders of magnitude faster. This has serious implications in the realm of cryptography, as current encryption methods rely on a classical computer's inability to factor large numbers in anything close to resembling real time. Since Quantum Computers work in parallel by nature, any problem that can be broken down into a parallel solution (or solutions) would run many times faster on such a device. Consider the realm of board games. In Chess, ultra-fast computers use brute force to search move after move, finding an optimal sequence of moves and then playing the first move in that sequence. If each branch of the main tree could be searched in parallel, then the speed at which the next "best" move is derived would increase drastically. A quantum approach may be applicable to the ancient board game Go. The field of artificial intelligence (AI) may be profoundly influenced by quantum computers. Imagine a machine capable of calculating through several tasks, simultaneously, then coming up with the optimal solution to the problem, in real-time. With the advances that we have seen in the realm of speech recognition, coupled with the brutal computational power possessed by quantum machines, it is easy to foresee a day when we might talk to our computers ... and they'll respond intelligently. Quantum entanglement gives quantum computers the ability to perform a "not" operation for free. Since the spin of two entangled electrons is fixed and opposite with respect to each electron, if one electron is set to a known spin (that is, up versus down), then the second electron must, instantly acquire the opposite spin of the first. Quantum Communication In an entangled system, the entanglement will persist until a measurement is made against one of the entangled parties. The act of measuring the system collapses the wave into a known state. This result would seem to end the possibility of using an entangled system for instantaneous communications. Adiabatic perturbation is a subtle side-effect of an atom's motion. If two atoms were entangled, it may be possible to influence this slight motion without collapsing the wave into a known state. Since, by definition, an entangled state means that whatever happens to one particle happens to the other, slight perturbations may have a detectable correlated response. Quantum Teleportation From the link above, here is where they have observed entanglement operating over billions of miles distance How do physicists know entanglement works over billions of miles? To date, researchers have only observed the effects of quantum entanglement over a distance of several miles ... since we don't have the technology to observe the effect first-hand at distances spanning much more than that of the Earth and Moon. However, a cosmological experiment was done using quasar 0957+561A,B (Entanglement, The Greatest Mystery in Physics, by Amir D. Aczel pp.92-93) that showed how a photon can simultaneously travel two paths across great distances. A galaxy splits the space between Earth and the quasar, acting as a gravitational lens, thus creating two light rays separated by 50,000 light years. When we observe the arrival of a photon we can, by using half-silvered mirrors, determine which ray the photon travelled or whether it travelled both rays. What makes this experiment interesting is that when we put in the silvered mirror (or not), the photon has already passed the galaxy! In effect, we wind up changing history. I urge you to read Dr Aczel's book for details. This doesn't show that the effects of entanglement persist across great distances, but it does serve to illuminate that some quantum behaviour is consistent at these lengths. |
Does it convey "information"? I.e. if I observe one entangled atom at point A, do I have any control over what an observer at point B sees in the other entangled atom? If not, then I am not communicating. We are merely observing the same phenomenon at different points, and since the information propagated to each of us at sub-light speeds (through the entangled atoms), relativistic causality is not violated. |
From the referenced article
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As long as you can reliably produce entangled pairs and ship them to the distant galaxies, sure. :) Jim |
 The states of the entangled particles are identical. The fact that you (even "perturbatively") observe the state of one particle does not mean that the other is "changed". You could not "observe" that correlation in the other particle without perturbing its state. |
Only if gravity waves propagate faster than light. So far, theory seems to dictate that they are limited to the same speed as light. The LIGO and LISA experiments might help us figure this one out soon. Jim |
To travel faster than light, according to Einstein, is to travel backwards in time So, to answer your question, you would need only to send a signal at whatever speed you are traveling. the trick is to not go back too far in time so as to be able to recieve your own transmission when you slow down One faster than light paradox is this : picture two towers able to transmit messages faster than light tower 1 sends message to 2 tower 2 sends 'message rcvd' signal since the message is faster than light, tower 2 actually recieves the message before it's sent tower 1 decides to wait a few minutes to send the signal, but recieves a 'message rcvd' back from tower 2 'before' they ever sent it reference : Beyond Infinity by Rudy Rucker |
BAH! Experiments...phooey. You'll find that many people here would rather blatantly assert than experiment. 
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Here is a good article on Bell's theorem of "spooky action at a distance", which has been demonstrated to be correct in labs at least. www.ncsu.edu/felder-public/kenny/papers/bell.html If FTL communications IS possible, I believe it will depend upon this principle. |
Do remember that Einstein's theory of the universe is not the only theory that has been proven correct - so has Quantum Theory - and they OFTEN produce opposite predictions. That is why the holy grail of physics is the Unified Theory of Everything, that explains both sides of things. Quantum Physics has disproved locality by demonstrating the reality of quantum entanglement, which is contradictory to some aspects of special relativity. |
Actually, neither have been proven "correct". |
Both Special and General Relativity have made predictions that have proven more accurate than Newtonian physics, in the predicting the moon's behavior and in the bending of light during a solar eclipse. Quantum Physics has been demonstrated over and over to be able to predict many things at a subatomic level. They are the best we have right now, though many physicists are looking for some theory to explain things at a macro and at a micro level, to the same degree that Relativity and Quantum Physics do, WITHOUT the apparent prima facea contradictions - String Theory is one such attempt to unify things, and its an attempt to explain all the "forces" observed by physics, such as strong force, weak force, electromagnetic force, and gravitational force. |
They've both made some correct predictions in some cases; that is not at all the same as being "proven correct". They've also made wrong predictions in some cases, don't even address some issues at all, and contradict each other on others. It's fairly convincing evidence that neither is the "correct" model. |
Physic is, and will always be, a work in progress. The theories of relativity and quantum theory are useful tools that have provided us such things as the laser and the microprocessor. One day, some genius will come up with another theory that will be even more correct, that explains more than either theory does now, that hopefully unifies some aspects (such as how Maxwell unified Electricity and Magnetism), but they are the most "correct" theories that we have at the current time. To borrow from Einstein, "correct" is a relative term. They are more correct than Newtonian physics. |
They might make many correct predictions, but they are not "proven correct". |
I understand that a unified theory has not been found. I only wanted to illustrate the FTL communcations paradox 
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This has turned into a discussion of terminology that has nothing to do with FTL communication. A theory can make more correct predictions than a previous one, and it still does not mean it is "correct" or "proven correct". A theory is only "proven correct" if it predicts every single case correctly. |
Well, I have done both experimental and theoretical work, so I can sit firmly on the fence and laugh at both sides. 
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What's worse is that they both have been proven "correct" to high degrees of certainty, and they contradict each other. They are useful for different realms of observations, so experiments are usually looking only at relativistic effects or only at quantum effects. This is a threshhold point in physics, like with the Rayleigh-Jeans Catastrophe (around 1900, the solution laid the groundwork for quantum theory). A successful successor to relativistic and quantum physics will incorporate both, and may lead to new understandings and uses of physical phenomena that we can't even imagine now. Jim |
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I've often thought that it's probably better that I'm not a quantum physicist at the top of the game. Knowing what they do, I'd be entirely TOO creeped out to get much sleep! Personally, I'm really starting to believe that every super whammy technological invention you've ever seen or read about in science fiction, be it transporters, warp drive, instant teleportation discs, even bidirectional time travel....will all be possible eventually. I hope it happens sooner rather than later because I really, REALLY want to go to the Planet of Gorgeous, Intelligent, Sensible, Non-Jealous, Playful, Horny Virgin Women With No Hangups, No Exes or Kids, No Baggage, No PMS, and No Communicable Diseases. Yes, that's a place I'd like to visit! CJ |
and instead of using the particles to communicate, how about the actual method that those particles DO communicate with???? |
Time to break out The Macallan on this one and go for the gold! 
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You will communicate face to face. Why send a message when you're going to be there in just a little bit anyway? Why do you want or need to send messages? Maybe you want to show up and be the star traveling gods the inhabitants of a new planet have been waiting on for eons. Maybe you need to show up to blow the shit out of something. You might not want to phone home, either, in case you don't want to be found, or don't want to share all the booty you found. Who will you comunicate with? If you are the first visitors, there ain't no one home til you get there. No point in sending a message home, you'll be back soon anyway. Even with Fast as Light travel, we aren't going very far in terms of the Universe's dimensions. That is a calming thought, in my opinion, knowing that the goings on in the greater volume of the Universe will always be a mystery. Speculation and deaming limited only by our imaginings, yet limited by the same. |