Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Everything in the universe is related

  1. Aug 14, 2005 #1
    According to the Theory of Relativity, "Everything in the universe is related."
    Can you explain this.

    And one more question. If Einstein didn't start it, Who started the Theory of Relativity?
  2. jcsd
  3. Aug 14, 2005 #2
    Where did you hear this? This is not even close to what relativity says. According relativity space and time are relative. This means that people moving at different speeds have different concepts of space and time, unlike Newtonian physics in which space and time are absolute concepts. This is, of course, just a very brief idea of what the theory of relativity is.

    The major players in the discovery of the special theory of relativity were Lorentz, Larmor, Poincare, and Einstein. Lorentz derived the Lorentz transformation equations, which are the most valuable equations in special relativity; I'm not sure what Larmor's contribution was; Poincare came very close to beating Einstein to a full development of special relativity, he is most noted for pursuing the principle of relativity (in the restricted sense) which states that all inertial reference frames are equivalent for the description of the laws of nature; and Einstein took the insights of the special theory of relativity the furthest and did away with the ether.

    The major players in the discovery of the general theory of relativity were Einstein and Hilbert. Einstein developed most of the insights for the theory; Hilbert contributed to the math.

    edit: Perhaps Minkowski should be mentioned as an important player as well. Minkowski unified the concepts of space and time into a single concept, spacetime. Minkowski played an important role in the transition from special relativity to general relativity. Although special relativity can be formulated without a Minkowskian view of spacetime, general relativity cannot.

    So you've got Lorentz, Larmor, Poincare, Minkowski, Hilbert, and Einstein who all contributed important pieces to the development of two theories of relativity (special and then general) in the early 20th century. Einstein's role was the most significant in the development and acceptance of both theories.
    Last edited: Aug 14, 2005
  4. Aug 14, 2005 #3


    User Avatar
    Homework Helper

    I think he meant: Everything in the universe is RELATIVE.
  5. Aug 14, 2005 #4
    Special Relativity says exactly the opposite because it says that the events in two moments separated by a distance greater than the distance that light can travel in the difference in the time between those two moments cannot affect each other in any way. It means that the most destuctive galaxy destroying event can occur in our galaxy without affecting life on earth for hundreds of generations.

    Maybe you are thinking of quantum mechanics, the EPR paradox, Bell's inequality and the downfall of local realism?
    Last edited by a moderator: Aug 14, 2005
  6. Aug 14, 2005 #5


    User Avatar
    Staff Emeritus
    Gold Member
    Dearly Missed

    So if you pay attention to the experienced posters on this forum, you now know that relativity doesn't say that everything is related, and if anyone tells you it does, you will know they are wrong and that they don't really understand relativity.

    On the origin of relativity, Lorentz proved his transformations of the Maxwell equations in the 1890s; these are at the heart of relativity. But Lorentz couldn't imagine how his equations could be physically real, because they seemed so paradoxical, mixing time and space in the same formula.

    Poincare could and did imagine how relativity physics would work but he didn't sit down and work out the transformations, or at least the paper in which he did the math wasn't published till after Einstein's. Even then he kept his development mathematical, and didn't address the physical results.

    Einstein worked out the physics of the Lorentz transformations and devised the theory of relativity independently of Poincare, but dependent on Lorentz, whom he admired. It was Einstein who showed how the length contraction and time dilation between relative frames of observation worked in terms of clocks and measuring sticks, and Einstein introduced the very important relativity of simultaneity, from which many physical consequences flow.
  7. Aug 14, 2005 #6


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    The "Principle of Relativity" was formulated by Galileo in his Dialogue Concerning the Two Chief World Systems
    Galileo's principle applied to mechanical experiments. Einstein extended it to include optical and electromagnetic experiments.

    Let me use your _words_ (but possibly with a different meaning from what you intended) to state an important (but often underappreciated) fact about Einstein's relativity. [This is in accord with what mitchellmckain said.]
    Events in the universe are not all causally-related. (This is different from the [spacetime] structure derived from Galileo's principle of relativity.)
  8. Aug 14, 2005 #7
    Maybe he means that the world is made of atoms.
  9. Aug 14, 2005 #8
    This is still not true. For instance, the speed of light isn't relative.
  10. Aug 17, 2005 #9
    I have been told by one of my friends that gravity and acceleration are related. How?
  11. Aug 17, 2005 #10


    User Avatar
    Science Advisor

    ?? Force= mass times acceleration. If you drop something, it acceleration downward is the gravitational force divided by the mass- that's how "gravity and acceleration are related".
  12. Aug 17, 2005 #11
    You are probably thinking of the equivalence principle, which is the basis for the general theory of relativity. In 1907, Einstein realized that if you are falling toward the Earth you will not feel your own weight. This "realization" seems pretty obvious, but Einstein went crazy with it. If you are in a rocket ship accelerating at 9.8 m/s^2, then you will feel your own weight, and any experiment you carry out will have the same results as an experiment done on Earth. For instance, if you hold out a ball and drop it, you'll see it fall to the ground with the same acceleration as a ball falling to the ground would on Earth. Based on this, Einstein declared that if you are falling toward the Earth, you are (locally) inertial (non-accelerating), but if you are standing on the Earth, since you are being pushed up by the ground in a similar manner to being pushed up by the space ship, you can be thought of as non-inertial. Because of this equivalence between gravity and acceleration, it is also possible for you in your rocket ship to declare that you are standing still and there is a gravitational field pulling everything in your rocketship down.

    A good description of some of these concepts can be found in Einstein's Relativity: The Special and General Theory, Section 20.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook