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Relativity

For discussion of problems relating to special and general relativity.

  1. Started by Nicholas,

    I offer this as the mechanism behind Relativity. Imagine that dimensions are not static. That they somehow "move." What would happen if you caught up to this motion? Time would go slower and space would shrink. I say everything in the universe is moving. You can't even pin down dimensions. With the advent of Einstein we know dimenisons "curve." I say they move! This also explains why the effects of motion are not reciprocal. Only the accelerated(who experience weight) will see the clocks left behind run fast(blueshift).

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  2. Started by Sid_Rat,

    Is there a relationship between inertial mass, rest mass and temperature? If a body's inertial mass and rest mass are the same then presumably its temperature is exactly zero degrees Kelvin (hypothetically of course). Might it then be possible to deduce the temperature of a body if you already knew the values both for rest and inertial mass ?

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  3. Started by pljames,

    My science friends, I feel I understand the basics of relativity. My perception is, if you are observing a object (lets call it object (b)) from point (a), (reguardless of the velocity of the object (b) in space and there is also another person (observer © is quite a distants away as well, both observer (a)&© are viewing the object (b) from different angles but are still relative in there own positions to object (b), even if object (b) is moving (reguardless of toward or away from you) at the time. This is how I percieve Einsteins theory. I am close, out of the universe or just another stab in the dark at what I think about the theory? I need your help in satisfi…

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  4. Started by Mart,

    Have I got this correct? The Twin Paradox can be resolved by showing that only one of the twins undergoes acceleration in order to return to base. So what has the value of their relative velocity got to do with the paradox?

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  5. If the fabric of space is expanding then the distances between galaxies is expanding, but this must also mean that the galaxies themselves are expanding. If this is so, then isnt that the equivalent of space staying constant and the ratio of light-speed to time changing? We presume that space is expanding because galaxies are moving apart too fast, but what if the reason they appear to be moving was just because the light was emmitted at a date when time was slower, and now that it is faster the light reaches us and it appears to be severely red shifted. After a certain distance time would have been too slow for it too have reached us yet explaining why it is unobservable…

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  6. Started by Davros,

    I am not a scientist but have a general interest in relativity. I am annoyed by the ever growing need to introduce exotic matter and additional dimensions into theories to account for effects in our universe. I have what maybe a completely silly idea (but would really like that to be confirmed! ) that may have a germ of interest .... 1. Suppose that the maximum velocity posssible in our universe was 0.0000005% higher than c. Call this c++. 2. light still has a measurable velocity c. But c is less than c++. Possibly from this a photon has mass. 3. If a photon has mass, why have we not detected it? Maybe because it is so so minimal. So minimal that even…

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  7. Guest vukelja
    Started by Guest vukelja,

    I wrote a new article titled "Triangle of Velocities", in which I show that relativistic expressions are possible in classical context, and are solution to a fairly simple problem. No bizarre interpretations are needed, no relativity of simultaneity or invariance of c, just a properly defined triangle. See at http://www.masstheory.org/triangle_of_velocities.pdf [38 KB] Previous version of this article, which is focused on Einstein's 1920 ``simple'' derivation of Lorentz transformation is available at http://www.masstheory.org/lorentz.pdf [127 KB] Aleksandar

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  8. Started by ydoaPs,

    http://members.tripod.com/da_theoretical1/wdt2.pdf http://members.tripod.com/da_theoretical1/wdt3.pdf http://members.tripod.com/da_theoretical1/warpcourse.pdf

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  9. Started by iglak,

    the thought experiment of time slowing down for a spaceship traveling the solar system says that the person on the spaceship will age the amount of time observed by him, and the person on the planet will age the amount of time observed by him. the person on the spaceship's reference frame is invalid, because inconsistant acceleration defies SR and GR, while the person on the planet's reference frame remains valid. the person on the planet views time slowing down for the person moving near the speed of light. there are a few problems with this, however. first, time is not the only thing of which the measurement decreases. length also decreases. so, by this experiment…

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  10. I got a few questions. Did the particles and stuff from the big bang move out faster then the speed of light and if so, how? Would that mean that we can see one end of the universe but not the other on account of the universe not being old enough to see the other side? (assuming the earth is not in the center of the universe) All I really know about the big bang is it was space and matter and energy and whatever else compressed to a singularity, then exploded, shooting particles and elements and eventually after a very long time of expansion and all that hoo-ha, dust and what not started to form together and start spawning stars...which sorta stuck to gravity centers.…

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  11. I heard that einstein created a theorum about how at higher speeds, time moves at different pace. Does anybody think this is possible?

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  12. Guest cephiyr
    Started by Guest cephiyr,

    I have a question on a part of the relativity theory that seems paradox to me. As far as I understand, a space craft travelling away from Planet Earth at high speed (i.e. close to c) will increase in mass and move slower through time. Thus the Astronaut onboard will age slower and when he gets back, everyone around him will have aged quicker. What I dont understand is, how we can tell that Planet Earth isnt actually the one travelling close to c. What I mean is, since speed is relative to other objects in space, how do we know that it is the astronaut that will age quicker ? Wouldn't it be possible that we see Earth moving away from the space ship at almost c, thus lett…

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  13. Started by Jacques,

    Let have 10kg of gold and take a train. Because of the velocity, relativity tell me that I now have a little bit more gold ! Now I throw it at the same velocity as the train toward the back, to my friend who is beside the track. Again because of the velocity relative to me the mass is increased again... If I do that many times I will endup with a lot of gold Isn't that illogic ?

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  14. Started by GrandMasterK,

    If absolute zero is when particles come to a complete hault, then would the hottest temperature be when those particles are zooming around at light speed? If so, what temperature is that?

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  15. The original Sagnac Effect has photons traveling in opposite directions around a circular path The circle is turning and therefore the photons do not arrive at the physical emission point simultaneously. Einstein suggsted that the Sagnac Effect be "unwrapped" into a linear form (avoiding the noninertial aspects of circlar motion, re AE), which is presented here. The circumferences are 'unwarapped' and described in linear form. The Sagnac Effect is invariant in this form as were all the other variations through the history of the effect. Some may recognize the experimental arrangement below in the schematic that is published in various forms as an educational deganken…

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  16. Started by Jacques,

    Photon are considered a wave in some case like interference and as a particule in other case like the photo-electric effect. I imagine a wave of light leaving from a distant star like a sphere expanding in all directions. When that wave hit a photo detector or a CCD the behavior of that wave is like a particule. Does it mean that all the energy spread out on the sphere having many lights years of diameter is instanly concentrated on one pixel of my CCD ??? Is my image of a wave bad ??? Thanks

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  17. Started by luc,

    Right now I'm reading Hawking's "The large scale-structure of space time", and he uses constantly a quantity called Energy-momentum, though I can't see it defined anywhere. I've also read in some forum that in GR, total energy is not conserved, but energy-momentum is conserved. I think that perhaps energy-momentum is (Total energy + magnitude of 4-momentum), but I'm not sure. What exactly is energy-momentum?

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  18. Guest raines
    Started by Guest raines,

    Until recently, I had never been very interested in science or math. Now I am. I picked up a couple of books that looked interesting to me, and I'm currently trying my best to understand the basics of general relativity, special relativity, and superstring theory. However, I feel that I might be approaching concepts that are too advanced for me, and am wondering where I should begin. As far as prerequisite learning goes, I've just completed pre-calculus and physics, both of which were gifted courses. The books I'm reading, as aforementioned, are Zero: The Biography of a Dangerous Idea by Charles Seife, and The Elegant Universe by Brian Greene

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  19. Started by revprez,

    Quick question. Does positive definite energy momentum always imply a lengthened geodesic (compared to the vacuum state)? Also, is there an example of macroscopic indefinite energy momentum state in nature? Rev Prez

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  20. Started by towjyt,

    Since there is a difference between the rate at which time passes on Earth and the rate at which time passes on the Sun due to the time dialation factor, has anyone calculated how much time passes on the sun, while a year passes on Earth? I have read articles where it was stated that eventually the Sun would reach a stage where it would expand to a size larger than Earth's orbit, then after a while it would shrink down to dwarf size. Now these calculations involved an estimate of time, but it is unclear to me whether they are talking Sun time, or Earth time.

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  21. Started by Mowgli,

    At the core of SR is a definition of what is meant by two clocks being synchronous. Two clocks A and B are assumed to synchronize if a ray of light takes the same time to go from A to B as it will take to go from B to A. Simultaneity, on the other hand, can be defined as follows: two events X and Y are simultaneous to an observer O if light rays from X and Y reach O at the same time (as seen by O's clock.) Are these two definitions compatible? Cheers, Mowgli

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  22. Started by Mowgli,

    Shall we try a time dilation paradox, again? I have been trying in vain to locate a flaw in the thought experiment below... Imagine a train moving at a constant speed, so that its frame is an inertial frame. At the front end of the train, there is a clock with a trigger mechanism. When the train passes a pole by the track, the clock triggers and records the time reading. There are two poles by the track. Each of them has a similar clock, which triggers when the front end of the train passes it. The clocks on the poles have been carefully synchronized to avoid any ambiguity. The synchronization can be achieved, for instance, by putting the clocks next to each other a…

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  23. Started by ydoaPs,

    i am having a difficult time locating the GR equations for gravity with x amount of mass energy. could someone post them please?

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  24. Started by Jacques,

    Hi I have a little question that is bugging me: If time freeze at the speed of light, how is it possible for light to have a frequency other than 0 ?

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  25. Started by Obnoxious,

    What exactly is information? Not the type which is transferred by lightwaves or whatnot, but entanglement type information, where if one proton does something, the other also does it. And since it has no exact mass that reality can grasp, why can't it travel at, or greater than, lightspeed?

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