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    Theory Of Relativity

    Einstein's Theory Of Relativity says that we will never be able to travel at the speed of light. What are you guys thoughts on that?

    #2
    To question one of the most credited scientists of our entire species ever is a bold, yet stupid move.


    I will not even attempt to fathom why you have proposed this thread.

    Sig by Draygon.

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      #3
      Within our own space-time, we can't accelerate to the speed of light. As the energy reaches infinity. However, hyperspace or warp drive kind of circumvents this. Either one isn't actually going FTL within our frame (it just looks like it).

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        #4
        Originally posted by Davidtourniquet View Post
        Either one isn't actually going FTL within our frame (it just looks like it).
        Correction. It doesn't move faster than light in its own frame. In outside observer's frame it will appear to move FTL. That's the whole point.

        And since its General Relativity that allows for this, it's essentially Einstein answering his own problem. Though, it took mathematicians some time to come up with actual solutions that allow for this, and all of them still require negative energy densities.
        MWG Gate Network Simulation

        Looks familiar?

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          #5
          In science fiction, science can be easily thrown aside and ignored....so that rule may not exist in the Stargate universe.

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            #6
            Originally posted by K^2 View Post
            Correction. It doesn't move faster than light in its own frame. In outside observer's frame it will appear to move FTL. That's the whole point.

            And since its General Relativity that allows for this, it's essentially Einstein answering his own problem. Though, it took mathematicians some time to come up with actual solutions that allow for this, and all of them still require negative energy densities.
            Aren't Kerr ring singularities a form of wormhole that doesn't require negative energy density ? According to wikipedia ( http://en.wikipedia.org/wiki/Ring_singularity ):
            This is not necessarily true with a Kerr black hole. An observer falling into a Kerr black hole may be able to avoid the central singularity, by making clever use of the inner event horizon associated with this class of black hole. This makes it possible for the Kerr black hole to act as a sort of wormhole, possibly even a traversable wormhole.

            If a ring-singularity forms, and is traversable, it may hypothetically connect either two different universes, or two distant parts of the same universe. The path through the ring technically counts as a special class of wormhole. It has been suggested [2] that with two widely-separated Kerr-singularities, it is geometrically allowable that the rings could cross-connect, such that a traveler could enter one ring and exit the other. This would then count as a class of singularity-bounded planar wormhole. It is not obvious how one would go about constructing such a cross-connection.

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              #7
              That's not all there is to it. Yes, this helps to make wormhole traversable. That is, there is a path going through it along which you never need to exceed the speed of light. But you still need to come up with geometry that connects two regions of flat space-time, and yet has only positive energy densities as source of curvature. No such solutions are known. Doesn't mean they are not possible, but nobody has yet figured it out.

              Edit: But yes. If I was to look for a naturally occurring traversable wormhole, I'd be looking at Kerr black holes. I'd also want them to be supermassive, so the nearest candidate for one is the black hole at the center of our galaxy. Fact that it is 26,000 light years from here makes experiments with it a bit difficult.
              MWG Gate Network Simulation

              Looks familiar?

              Comment


                #8
                Originally posted by K^2 View Post
                Correction. It doesn't move faster than light in its own frame. In outside observer's frame it will appear to move FTL. That's the whole point.

                And since its General Relativity that allows for this, it's essentially Einstein answering his own problem. Though, it took mathematicians some time to come up with actual solutions that allow for this, and all of them still require negative energy densities.
                As I said it isn't actually travelling FTL, it just looks like it, as it has travelled so many light years in several seconds.

                Comment


                  #9
                  Originally posted by Replicator Todd View Post
                  In science fiction, science can be easily thrown aside and ignored....so that rule may not exist in the Stargate universe.
                  Not true. Just... worked round.


                  "Five Rounds Rapid"

                  sigpic

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                    #10
                    It's actually ironic that I started this thread yet don't understand the theory of relativity at all. I've been trying to understand it using wiki but can't grasp it at all. Would someone be able to explain it to me simply.

                    Is it this:

                    An event may be observed differently by two different people depending on something....

                    I'm not that knowledgeable when it comes to physics. Studying it for my Leaving Certificate but have only done basic stuff such as mirrors and lenses, sound etc.

                    Comment


                      #11
                      Lets start with Galilean Relativity for simplicity. This is how people imagined the world pre-Einstein. Lets say I stand on one side of the room, and my friend stands on the other. In the middle of the room something happens. To me, it happens a few feet to the West. To my friend, a few feet to the East. Because of our different position, we are going to disagree on where the event happened relative to ourselves. But if we take into account our own positions relative to each other, we will once again be in agreement. Regardless, however, both of us will agree on when the event happened, as long as both of us have precise watches.

                      This is the basis of any relativity. Description of event changes depending on location and motion of the observer who is describing it.

                      Now, lets talk about relative motion, still in Galilean Relativity. Imagine a car driving on a road due North at 40 mph. A person on the ground can use a police radar to confirm that it is so. Imagine, now, that I'm on a train also going North, but at 60 mph, and I try to determine the velocity of the car. I can verify that it appears to move to the South relative to me, and I can use a police radar to confirm that it is moving at 20mph. I find myself in disagreement with a person who is standing on the ground. But once I note that this person, relative to me, is moving South at 60mph, I can easily make a correction.

                      Here comes a problem. Speed of light turned out to be invariant. That is, both myself on a train and person on the ground must measure exactly the same speed for a beam of light traveling North. This is a clear violation of Galilean Relativity, and was the first sign that something was wrong with it.

                      At this point, comes a bunch of reasoning that Einstein wen through to come up with a way to correct for all of this. Many of the equations he came up with were already known in Electrodynamics, but the reason for them was not fully understood.

                      With all of the corrections taken into account, some interesting and counterintuitive things come to light.

                      1) If both myself (still on a train) and a person on the ground observe aforementioned car flash its lights, we will not only disagree on where it happens, but also on when it happens, even after taking delay of light propagation into account. Worse yet, if we compare it to timing of another event that happened elsewhere, we might disagree on order in which events happened.

                      2) The sum of car's speed relative to person standing on the ground and relative to train, will not add up to the speed of the train. It will be a little bit greater.

                      3) If the person on the ground measures the length of the train, he'll come up with a different number than if I measure it while on the train.

                      You need to understand that in any realistic scenario, where train isn't moving nearly at the speed of light, the difference will be tiny. Typically, it will not be measurable. However, such effects have been verified in more extreme cases. GPS satellites have to take these corrections into account in order to achieve precision they have. On particle accelerators, this isn't just a correction anymore, but normal way of things, since everything is traveling very near the speed of light there.

                      And that's just Special Relativity. When you take into account that observers may also accelerate differently, you venture into realm of General Relativity, and things get really messed up.
                      MWG Gate Network Simulation

                      Looks familiar?

                      Comment


                        #12
                        Originally posted by K^2 View Post
                        Lets start with Galilean Relativity for simplicity. This is how people imagined the world pre-Einstein. Lets say I stand on one side of the room, and my friend stands on the other. In the middle of the room something happens. To me, it happens a few feet to the West. To my friend, a few feet to the East. Because of our different position, we are going to disagree on where the event happened relative to ourselves. But if we take into account our own positions relative to each other, we will once again be in agreement. Regardless, however, both of us will agree on when the event happened, as long as both of us have precise watches.

                        This is the basis of any relativity. Description of event changes depending on location and motion of the observer who is describing it.

                        Now, lets talk about relative motion, still in Galilean Relativity. Imagine a car driving on a road due North at 40 mph. A person on the ground can use a police radar to confirm that it is so. Imagine, now, that I'm on a train also going North, but at 60 mph, and I try to determine the velocity of the car. I can verify that it appears to move to the South relative to me, and I can use a police radar to confirm that it is moving at 20mph. I find myself in disagreement with a person who is standing on the ground. But once I note that this person, relative to me, is moving South at 60mph, I can easily make a correction.

                        Here comes a problem. Speed of light turned out to be invariant. That is, both myself on a train and person on the ground must measure exactly the same speed for a beam of light traveling North. This is a clear violation of Galilean Relativity, and was the first sign that something was wrong with it.

                        At this point, comes a bunch of reasoning that Einstein wen through to come up with a way to correct for all of this. Many of the equations he came up with were already known in Electrodynamics, but the reason for them was not fully understood.

                        With all of the corrections taken into account, some interesting and counterintuitive things come to light.

                        1) If both myself (still on a train) and a person on the ground observe aforementioned car flash its lights, we will not only disagree on where it happens, but also on when it happens, even after taking delay of light propagation into account. Worse yet, if we compare it to timing of another event that happened elsewhere, we might disagree on order in which events happened.

                        2) The sum of car's speed relative to person standing on the ground and relative to train, will not add up to the speed of the train. It will be a little bit greater.

                        3) If the person on the ground measures the length of the train, he'll come up with a different number than if I measure it while on the train.

                        You need to understand that in any realistic scenario, where train isn't moving nearly at the speed of light, the difference will be tiny. Typically, it will not be measurable. However, such effects have been verified in more extreme cases. GPS satellites have to take these corrections into account in order to achieve precision they have. On particle accelerators, this isn't just a correction anymore, but normal way of things, since everything is traveling very near the speed of light there.

                        And that's just Special Relativity. When you take into account that observers may also accelerate differently, you venture into realm of General Relativity, and things get really messed up.

                        Great explanation. VERY Simple Theory to understand but I was wrecked last night when I was reading it, it was like 12 and I had a long day and the wording on wiki is quite confusing.

                        One thing I don't get is "2) The sum of car's speed relative to person standing on the ground and relative to train, will not add up to the speed of the train. It will be a little bit greater."


                        Is it that the speed of the car in the persons on the ground opinion will not be as fast as the speed of the train relative to the person on the ground?

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                          #13
                          If you have 2 objects travelling close to c, heading towards each other. From the point of view of one of the objects, the other will not seem to be travelling above c, like they would in a newtonian universe.

                          Comment


                            #14
                            Originally posted by Lotto View Post
                            Einstein's Theory Of Relativity says that we will never be able to travel at the speed of light. What are you guys thoughts on that?
                            The laws of Physics as we know them now are going to change, its just inevitable. Right now it goes against everything that we know about physics. But 200 years ago they said the same about what we are doing now. Things change. One day I have a feeling that will reach FTL speeds. But we just can't do that now because it goes against everything we know about physics.
                            Last edited by Medicman; 20 December 2009, 03:46 AM.
                            Jack O'Neill: If we want to find out who's behind this, we have to do what the Asgard do.
                            Daniel: You mean bluff?
                            Jack O'Neill: Yep. We just need to do it without revealing what we know.
                            Daniel: Which is nothing.
                            Jack O'Neill: Right. But they don't know we know nothing.

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                              #15
                              Originally posted by Lotto View Post
                              One thing I don't get is "2) The sum of car's speed relative to person standing on the ground and relative to train, will not add up to the speed of the train. It will be a little bit greater."


                              Is it that the speed of the car in the persons on the ground opinion will not be as fast as the speed of the train relative to the person on the ground?
                              No. It's about adding speeds together. Let me try to rephrase it.

                              Imagine that the person on the car wants to know how fast the train is going. He can measure the speed of the train relative to car (20mph). And he knows how fast he is going by measuring speed of objects on the ground (40mph). Normally, you'd expect him to conclude that the train is moving at 40mph + 20mph = 60mph. But a person on the ground, measuring the train's speed, will see a number that is somewhat less than 60mph.

                              Davidtourniquet mentions a more extreme example from which you see that speeds can't just add to each other. Two objects can move at more than half the speed of light, but they must still move at less than speed of light relative to each other. Clearly, you can't just add velocities.

                              There are formulae that correct for this stuff, of course.
                              MWG Gate Network Simulation

                              Looks familiar?

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