| Einstein's Theory of Relativity | |
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CuZzA - Student  |
As most of you all know, Einstein's theory of Relativity is being tried out as the space shuttle took lift off in Calafornia this afternoon. If this is right, then it's possible (if we go the correct speed) to go back in time right? Imagine what you could do. Stop world wars, invent the handshake, be the first one to run up a wall or something lol so what do you guys think about it? I personally think its a great topic to talk about  _______________ - Even if Carlsberg made "w*nkers", Christiano Ronaldo would still be the biggest "w*nker" in the world This post was edited by CuZzA on Apr 20 2004 06:59pm. |
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n00b - Student 
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What I found particualrly interesting about GR was that the whole notion was based off of the first theory of special relativity. I could find no real explanation beyond shear hypothesis that Einstein's observations in fact were caused by a slowing of a particle's internal clock. What is apparent from the observation is that the equations of movement of a particle approaching the speed of light needed serious modification. In a nutshell Einstein observed that a particle seemed to "live" i.e. take longer to decay when it approached the speed of light. Does this necessarily mean that time actually slowed down for the particle or that some other factor was involved? GR predicts a whole lot about gravitational effects but just because the relationships in the equation may somewhat model what reality may be, it does not mean the phenomenon is a direct cause of the relationships. We don't understand at all why the universe is as it is and most likely never will. Our measurements and models give us the technology to predict, that is all. As an example, GR predicts the existence of black holes in outer space, but to this day we haven't actually found one. Scientists are asked to explain what they see and why it is occurring, but they usually have no idea. They see something, they measure it using all the measurement systems we currently understand, then come up with equations predicting the behavior. An interesting somewhat famous experiment that happened in 2000 by a Lijun Wang was the propagation of light waves through a cesium medium. GR says that the cosmic speed limit is the speed of light in a vacuum. The scientists at first announced that they had "sped light up" by 310 times its normal speed. Upon further investigation, they claimed that the light wave did not speed up, but it seemed to take negative time to reach the other side of the cesium medium. To me it looks like the light wave is doing something we definitely did not know light could do. It seems to displace itself on the axis of motion when a medium has a negative index of refraction as in the case of the cesium. Overall the light wave reaches the final destination sooner than a light wave not passing through the medium. I'm sure all kinds of mathematics could be derived to predict this phenomenon. Is there an effect on normal time or is something else actually occuring? Based on the fact that math describing the motion of objects uses time in its equations, it may actually appear in pure mathematical terms that time is bending in some way. It could be that time is a poor way to measure light propagation if our known methods break down as in this case. Will we ever really understand what makes light do that? Most likely not. Gain Assisted Superluminal Light Propagation (faster than the speed of light) homepage: http://www.neci.nj.nec.com/homepages/lwan/gas.htm Stephen Hawking Quote: What is it that breathes fire into the equations and makes a universe for them to describe? Awesome page on GR: http://archive.ncsa.uiuc.edu/Cyberia/NumRel/NumRelHome.html _______________ Gone but hopefully not forgotten... This comment was edited by n00b on Apr 30 2004 05:16am. |
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Notation - Student 
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Bump. I love reading about this stuff.  |
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n00b - Student
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If anyone thinks we can go backward in time based on some equations that may or may not be 100% accurate, feel free. I myself believe time travel is pure science fiction. What equations don't give us is meaning or an answer to why. Equations are also models of what we *think" reality is. Mathematics may help give us the idea of what to measure next, but they never explain anything in terms other than relationships. Time and time again in history, philosophers have tried to explain things based on mathematics, but they always end up sounding rediculous in the end. Take for instance, the notion of ether. Ha ha. Based on math and observations of waves in water, philosophers speculated that light had to travel in some medium. Then we got to space and realized it was all a bunch of nonsense. Take a mathematics model for what its worth and forget all the philosophy. Remember the fundamental principle in science is to observe. Where's time travel happening in nature? _______________ Gone but hopefully not forgotten... |
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JavaGuy - Student 
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n00b--You're talking about Special Relativity, not General Relativity. And no, Godel's solution to GR is not "putting words into his mouth." It's just a solution to Einstein's equations. It's mathematics. Ancient is correct that Einstein himself didn't discover CTCs, but they are one solution to his equations, not some new postulate. _______________ My signature is only one line. You're welcome. |
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Ancient - Ex-Student 
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Quote: No, Kurt Godel discovered "closed time-like curves," which are simply one possible solution to GR. A CTC is simply a worldline that a particle can follow that ends in the same place and time that it started. This isn't freaky quantum stuff, just plain-vanilla GR. As a practical matter, though, Godel's solution doesn't yield a buildable time machine. One proposal involves going into a black hole--interesting thought experiment, but you would not live to see the results. Another suggestion involved infinitely long cylinders, which also has obvious problems. Mathematically, the structure of the universe may allow for time travel, but actually doing it is another matter. Like I said, the universe never actually lets us look when it's doing something ugly. Sometimes I find it very disturbing to think about this stuff. For example: Either the age of the universe is finite, or it is not. Philosophically, I find either prospect absolutely horrifying. Yes, but this is already not Einstien's theory of relativity, right? At least not "Einstien" _______________ -THE ONE WITH THE "STAFF" -BROTHER TO FROSTY -Admitted to University of California, San Diego(UCSD). YAY! |
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n00b - Student 
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Quote: well, lets just say every one of Einsteins theorys up to now have been correct Einstein never said things could go backwards in time. What he did say is that a particle's clock moves slower when travelling close to the speed of light. This means as you approach the speed of light, the time slowdown gets larger and larger. It doesn't take too much stretch of the imagination to say that if you were going the speed of light, the particle's clock would stop completely. It would then seem to follow that if you could could accelerate beyond the speed of light, the clock would tick backwards. It has been shown that Einstein is right on the money with the time dilation effect of radioactive particles approaching the speed of light as they decay. This other notion that other people have about reversing time is putting words into his mouth and is totally unproven. _______________ Gone but hopefully not forgotten... This comment was edited by n00b on Apr 24 2004 05:18am. |
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CuZzA - Student 
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Quote: The idea that Einstein was suggesting that we could go backwards in time is utter nonsense. well, lets just say every one of Einsteins theorys up to now have been correct _______________ - Even if Carlsberg made "w*nkers", Christiano Ronaldo would still be the biggest "w*nker" in the world |
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n00b - Student
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The idea that Einstein was suggesting that we could go backwards in time is utter nonsense. _______________ Gone but hopefully not forgotten... |
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JavaGuy - Student 
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No, Kurt Godel discovered "closed time-like curves," which are simply one possible solution to GR. A CTC is simply a worldline that a particle can follow that ends in the same place and time that it started. This isn't freaky quantum stuff, just plain-vanilla GR. As a practical matter, though, Godel's solution doesn't yield a buildable time machine. One proposal involves going into a black hole--interesting thought experiment, but you would not live to see the results. Another suggestion involved infinitely long cylinders, which also has obvious problems. Mathematically, the structure of the universe may allow for time travel, but actually doing it is another matter. Like I said, the universe never actually lets us look when it's doing something ugly. Sometimes I find it very disturbing to think about this stuff. For example: Either the age of the universe is finite, or it is not. Philosophically, I find either prospect absolutely horrifying. _______________ My signature is only one line. You're welcome. |
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Ancient - Ex-Student 
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Quote: well, i heared somewhere that if u go fast enough theres a possiblity that u might go back in time somehow, but i dont think its true but still. Is actually go forward in time, the special theory of relativity addressed that. The theory was also proven by accelarting some unstable element to 70percent of light speed and the life time of that unstable element really get longer, allow scientist to do experiment and further study to that element. _______________ -THE ONE WITH THE "STAFF" -BROTHER TO FROSTY -Admitted to University of California, San Diego(UCSD). YAY! |
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Ancient - Ex-Student
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From what i know the general theory of relativity only addressed that any mass in this universe can distort the 7 dimentions that we cannot see. And this effect, give us a new perspective to look at the newton's law of gravitation. However, the general theory of relativity never said that we can go back in time. Maybe we can find out another way to go back in time in the furture....who knows... _______________ -THE ONE WITH THE "STAFF" -BROTHER TO FROSTY -Admitted to University of California, San Diego(UCSD). YAY! |
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JavaGuy - Student
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Ancient...General Relativity (not special) actually does allow for travel backwards in time...and I'm a little out of my depth here...but never in a way that we would consider "meaningful." Just as the universe never lets you see a naked singularity, it hides other bits of ugliness from us as well. Again, this is a bit beyond my depth, but that's my understanding of it. _______________ My signature is only one line. You're welcome. |
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BlueDragon - Ex-Student 
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Star Trek episodes on time travel seem to have too many paradoxes. They screw up too much. The warp drive is just like you said, which is why the Entreprise seems to stretch when going at warp speed. The hyperdrive is different in that it sorta puts the spaceship in a different dimension where it can travel without fear of hitting asteroids, which is why star trails appear, i believe. It uses some type of wormhole, I think. _______________ -BlueDragon This comment was edited by BlueDragon on Apr 23 2004 12:51am. |
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Squibit - Student 
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OK I must admit I understood only about half of what was said here but here a few of my (comparativly) primative thoughts 1) If only 1 timeline, and you can go back in time, conserning the killing of ones grand mother: If I am here, my grandmother was there! Therefor not killed so somthing Must have stopped me. eg. as I was about to shoot someone triped knocked me over and i hit my head on a rock and died. The police never did discover the identity of that unfortunate victim of an accident. 2)warpdrive (star trek but i assume hyperdrive is similar) are based on the idea that if spacetime is a sheet that can be curved then you can squish space infront of you and expand space behind you. there for you go forwards (red it in a book somehwere, dont ask me) 3) My favorite Star trek episodes are the K0ol time travel ones that get me so confused good topic people _______________ Quote: fiZZe: its SIR Fizzy Fluffy :p Quote: FiZZ[JAK]: that was what I call a counter Ah, things you only ever expect to hear once
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Johnnyrico - Student 
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well, i heared somewhere that if u go fast enough theres a possiblity that u might go back in time somehow, but i dont think its true but still. _______________ ...... |
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BlueDragon - Ex-Student 
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Quote: speaking of realativity....Check this out That was the reason why this thread started _______________ -BlueDragon |
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Garos - Student 
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I saw that on the news |
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Orion - Retired 
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speaking of realativity....Check this out _______________ When a Man lies he murder's some part of the world. These are the pale deaths which men misscall there lives. All this I cannot bear to witness any longer. Cannot the kingdom of salvation take me home? -Cliff Burton Owner of Smily's 1900th comment | <Lady_Catherine> i love your sexy white socks! | (Lady_Catherine) i adore u! | (Lady_Catherine) onion (Lady_Catherine) i lub u |
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Ancient - Ex-Student
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Quote: You can't get to the speed of light, and it has to do with time dilation. I'll spare you the math (unless somebody really wants to see it!), but basically as you get closer and closer to the speed of light, it takes more and more energy to accelerate less and less. There is no limit to how much energy it takes to keep getting closer to light speed, so it can't be reached. If you were travelling somewhere that you want to go at close to the speed of light, though, you'd probably be going somewhere far enough away that you wouldn't mind taking a few months to accelerate (and later, to slow down again). More, we can also see the impossibility of getting exactly to or reach the speed of light from the "relativity correction factor" of the equation, if we really get to the speed: 3.0*10^8 we will get a denomnator of "0" in the equations, and anything divided by 0 will become "infinite", we can see that from the introductory of calculas-- "limits". In another word, Energy will equal to infinite, mass will equal to infinite, length will equal to 0 {note that the correction factor for length is in nominator form}and the time will become infinitely SLOW, which will only happen in black hole _______________ -THE ONE WITH THE "STAFF" -BROTHER TO FROSTY -Admitted to University of California, San Diego(UCSD). YAY! |
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Ancient - Ex-Student
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I am sorry but i think you mistaken something.... Einstein's theory of relativity never addresses we can go backward in time, rather, it only say we can go forward in time. And we call that "TIME DILATION" this means that according to a stationary observer, a moving clock runs more slowly than an identical stationary clock by a factor, that factor depends on the speed of the moving clock,(the closer to speed of light, the time will move slower relative to the "stand still" clock) NOTE: if we walk at a very slow speed, we actually have a longer life than others, but the factor is toooooo small that we cant notice. The second factor of the theory of relativty is "LENGTH CONTRACTION", which means that as an object move at a speed (any speed), the length of that object parellel to the moving direction will contract in a factor. This factor is also depends on the speed you are moving.... The third factor addressed that a moving object will gain a factor of its own mass. In another word, anything that moves in a certain direction will gain additional mass. Like the first two theory, you will gain more mass as you approach the speed of light. The fourth factor is "RELATIVISTIC ENERGY", which addressed the point that mass is a form of energy, and even a small mass corresponds to an enormous amount of energy HOPE THAT HELPS....enjoy _______________ -THE ONE WITH THE "STAFF" -BROTHER TO FROSTY -Admitted to University of California, San Diego(UCSD). YAY! |
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BlueDragon - Ex-Student
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Well, I wouldn't know. I'm only 15 and haven't had physics yet I only read books on physics, alot mind you, which is why I know alot on these kinds of subjects for my age. _______________ -BlueDragon This comment was edited by BlueDragon on Apr 21 2004 11:46pm. |
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JavaGuy - Student
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Precisely. To clarify, modern physics no longer uses the idea of "relativistic mass," the increasing mass as something accelerates. You'll still sometimes hear physics profs teaching beginning relativity speak of relativistic mass for the sake of simplicity, but modern physics defines mass as rest energy (matter being just another form of energy). For purposes of calculating things like inertia and momentum, God's accountants don't really distinguish between matter and any other form of energy, so as you accelerate, i.e. as your kinetic energy increases, to the universe this is no different than if your mass were increasing. BTW, at 3g it would take a little over 118 days to approach the speed of light. _______________ My signature is only one line. You're welcome. |
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BlueDragon - Ex-Student
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That's pretty much in the same area as mass. The more mass it gets from accelerating, the more energy needed to keep it accelerating. _______________ -BlueDragon |
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JavaGuy - Student
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You can't get to the speed of light, and it has to do with time dilation. I'll spare you the math (unless somebody really wants to see it!), but basically as you get closer and closer to the speed of light, it takes more and more energy to accelerate less and less. There is no limit to how much energy it takes to keep getting closer to light speed, so it can't be reached. If you were travelling somewhere that you want to go at close to the speed of light, though, you'd probably be going somewhere far enough away that you wouldn't mind taking a few months to accelerate (and later, to slow down again). _______________ My signature is only one line. You're welcome. |
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BlueDragon - Ex-Student
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Another problem I forget to mention is acceleration. The faster a spacecraft with a crew accelerates, the more g's that get pushed on to the crew (like those fighter pilots making a tight turn). Now getting to Lightspeed instantaneously would kill the kill the entire, leaving nothing but lots of pancakes (assuming that the spaceship actually can withstand that much force). If one was to get to lightspeed on a comfortable 3g's (lets ignore the mass gets more thing), it would take a couple months before reaching the speed of light!!! _______________ -BlueDragon This comment was edited by BlueDragon on Apr 21 2004 09:00pm. |
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