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Relativity

For discussion of problems relating to special and general relativity.

  1. Started by O'Nero Samuel,

    Traveling with the speed of light, dt tends to zero(this is assumed to be relative to earth's time; which is dependent on the gravitational force around the earth). Is there a moving frame somewhere whose time relative to earth is not zero? Maybe due to its traveling speed, or maybe the gravitational force around it. Can anybody help with an explanation, or better still, where to search for answer?

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  2. Started by dr. undefined,

    Do you agree with the fact that Einstein introduced the curvature tensor taking it 0 to be legit?

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  3. Started by HerbertSu,

    Can somebody explain the Space Twin Paradox (the one where a twin goes into space and comes back younger than his/her other twin) in a simple, layman-like way? Thanks.

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  4. I want to get some ideas and oponions from my the people I've grown to admire here. Please check the paper I wrote called On the Concept of Mass in Relativity at http://arxiv.org/abs/0709.0687 Please take a glance throught it and let me know what you think. Let's start with the abstract. I changed my mind on what I want the purpose of this article should be about. I want it to address all the errors used in counter arguments used against the concept of relativity and to give counter examples where needed. Here's the abstract as it reads now. Mind you that I don;t wamt people to get the idea that I'm pushing the conecept of relativistic mass since people who know ab…

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  5. Started by Gobbleston,

    Hello, I originally had a fairly basic question about the twin paradox but when attempting to look it up, I clicked the Wikipedia article and it was totally chock full of equations relative to speed, and the Doppler effect, and other such things. I was led to believe that the twin paradox has to do more so with the two twins and their relation to one another based on the bending of space time because of their acceleration/mass. Einstein’s theory of general relativity basically means (as far as I know) that the faster an object moves, the greater its mass increases, and because objects of larger mass create a greater gravitational pull on space time, that would…

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  6. Started by RichIsnang,

    How do you work out the space-time curvature according to general relativity? Iv seen the special relativity equations, but never the general

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  7. Started by kuartus4,

    Hello. My name is A.J and I was wondering if I could get some feedback on a book about general relativity that I found on the web. The book is written by a former professor of mathematics named Robert A. Herrmann. It is entitled,"Nonstandard Analysis Applied to Special and General Relativity -The Theory of Infinitesimal Light-clocks" The author describes the book like this: "It is actually dangerous for me to present the material that appears within this book due to the usual misunderstandings. Any scientist who claims that there are fundamental errors within the foundational methods used to obtain Einstein's General and Special Theories of relativity may be greatly …

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  8. Started by Gobbleston,

    Hello again, One of the earlier findings behind the theory of relativity was measured distance between the sun and earth dependent on location. In the book I’m reading it isn’t too clear on this point, saying that two different people would get two different results, but because the speed of light is constant you would have to factor in a different of time levels instead of speed or distance. Now, I’ve been pondering this for a bit between having written this email (yesterday) and having posted it. At the beginning of my pondering I was thinking that even with the speed of light remaining constant, shouldn’t time and distance still measure proportionate to o…

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  9. As stated in theory of relativity, as the speed of any object inceases its relative time decreases. Is it not applicaple to light it self. At its very own speed light's relative time should be zero and it should reach earth for that matter instantly. your view pls

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  10. I finished the book well, because i understood the theory briefly before i read it, i can't understand the old theory that dominated the physics in 1800s the ether wind theory. So can some good people help me understand it ? I didn't really get the Mach's principle , ether wind theory, and in the book says so much how stuff can't travel faster or at speed of light, but a pair of huge scissors can because it is moving on a geometric point, i didn't get that. It was kind of confusing for me to read a English book because I'm Chinese. and last question, in the book it stated that in a space ship traveling at high speed, lets say 50% speed of c. lets…

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  11. Started by Gobbleston,

    Hello, So let me start of by saying that I am a high school graduate, but not a college one. Personally, I blame the California school system. Anyway, I have been reading A Brief History of Time by Stephen Hawking, because I have a great interest in learning as an adult. I understand a great deal of the book, but some of it I'm more of the "well, if you say so." attitude. I would prefer more understanding on these subject, so I imagine I'll have more than a few questions for here. So, my first bit of trouble is regarding Einstein's theory of general relativity, related to the equivalency principle. I get the basic gist of it, how light would behave the same …

  12. People often ask me about when proper mass can't work as good as relativistic mass or even better. I wrote an entire paper to answer this question but people don't read it carefully enough. Probably because they believe that no matter what the paper says they've already made up their mind because the already thought about it carefully alread a long time ago. And that is a good reason. I'd probably do the same thing - Too much reason with no real expectations of changing what they think in any sape or form So to take a shot at perhaps clarifying why physicists hold on to the notion of relativist mass. So I've decided to create a challenge for everyone. I have a SR tex…

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  13. Does the passage of time in the universe is uniform? A brief discussion paper on this subject is available on the link: http://dl.dropbox.com/u/26262175/TimeInUniverse.pdf Do the arguments presented in this article can be right?

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  14. Are Lorentz Transformation or their products having irreducible representation, and is superposition allowed or social consideration are needed??? Sorry meant special not social

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  15. Started by _heretic,

    What are the (theoretical) conditions required for some kind of non-orientable wormhole to form? Thanks,

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  16. Started by pmb,

    A friend of mine gave me a copy of the text Relativity: An Introduction to Special and General Relativity by Hans Stephani, Cambridge University Press, 2004. See www.cambridge.org/9780521811859 Seems like a very nice text. I wanted to point this one out because it seems like a great text for the student who wants to move on from simple relativity to more advanced relativity as well as general relativity. It too uses relativistic mass instead of proper mass and its relatively new.

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  17. Started by gooncorp,

    i am trying recreate light speed from the perspective of the moving object here is a video of my attempt this is a for a space simulator

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  18. Started by pmb,

    There is a new version of Exploring Black Holes comming out in the future. It's located at http://www.eftaylor.com/. See http://www.eftaylor.com/comments/ and http://exploringblackholes.com/. Once again I'll be proof reading for the authors. It'll be a great deal of fun. You can do the same thing if you wish. In any case it will be fun to talk about. Download the book and bind it and read it and let's chat!

  19. Started by pmb,

    I was wondering if anyone here has heard of the definition of Classical Mechanics which is defined in the well known, staple of classical mechanics Classical Mechanics - Third Edition by Goldstein, Safko and Pool, Pearson Education, Inc,. Publishing as Adison Wesley (2002). See page1, first paragraph I have, for the longest time, used this text, and as such this definition for classical mechanics. So if you see me use the term you can be certain that this is what I mean. But I certainly can't assume that this is what others mean by it. I'd like to make a request of you good folks to state the definition of classical mechanics as you choose to use the term, especi…

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  20. Started by pmb,

    I was wondering if any of you folks have heard the terms Active Gravitational Mass and Passive Gravitational Mass? Theoretically they are proportional to each other. You can choose constants of proportionality such that they're differerent, However, regardlesso how you chose those constants the densities of these quantities have the same value. A longtime ago I wrote a web page addressing this matter. I placed it here http://home.comcast....e_grav_mass.htm The density is seen in Eq. (3). Let rho = density of active gravitational density. As you can see from Eq. (3) rhoactive g-mass = u0 + 3p. I don't derive it on that page (but will create a new page soon) but…

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  21. Hello, I have some questions about General Relativity that I cant seem to get an answer. I read possible the universe can wrap back in on it self, so if you looked far enough in one direction you could see the back of your head. So this is understood as the space warping in 3 Dimensions. 1- But if the space is really empty & not like a trampoline surface (in 2D), than can you explain how the space doesn't have an edge or boundary if finite in spacial extent? This really bugs me unless I'm missing something obvious? I just don't know how a 3D universe that is curved having no boundary & being finite can be with empty space? thanks

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  22. Started by Widdekind,

    If gravity is a fictitious (pseudo) force, cp. centrifugal & Coriolis forces; then how could 'gravity' be exerted, through force-ful interactions, via boson exchanges, i.e. 'gravitons', any more than there are 'centrifugal-ons' or 'Coriolis-ons' ? The only actual forces, mediated by bosons, are the S,W,EM, of the Standard Model ? If so, why would quantum gravity be any other, than "solving the Schrodinger equation on a curved coordinate grid-mesh" ?

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  23. Started by nehemiahjacob,

    My kind Apologies in case this post doesn't qualify this forum

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  24. Started by Ben McKinney,

    What would happen if you used an ionic pulse inside of an oscillating magnetic field? would a high concentration of hydrogen make a difference?

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  25. Started by claforet,

    Hello, I have a question about the measurement of light speed and frequency. How are these physically measured? In particular, when we say the speed of light is constant, are we saying that the front tip of the wave always arrives at the same time or the end of the wave? I ask because it must take less time to resolve the frequency of a gamma ray, relative to a very long radio wave (i.e. the measurement of the frequency cannot be instantaneous). So the speed of information (which is frequency dependant) must not be constant (assuming one wavelength of any frequency corresponds to one unit of information). I'm just curious about the specifics of measurement and ca…

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