Einstein's Relativity

    In Einstein's theory of relativity, the length of any object get shortened if the relative velocity increased and at the velocity of light (C) it becomes zero. Will it really ?
    where, L= length for other frame, L0= length in it's own frame, v= Relative velocity, c= speed of light.
    Length seems to be shortened and actually being shortened are two different things.
  2. John Jaksich
    John Jaksich
    It is a "Limiting law" -----one can never attain the speed of light in Einstein's special theory of relativity. Only light can travel at that speed---while an object can (at most) attain ~99.9999...% of the speed of light. One must bear in mind that as one travels close to the speed of light---the actual mass of the object increases so --one cannot ever attain infinite mass nor infinite energy!
    If two light rays are travelling in opposite to each other then what will be their relative velocity ?

    Based on Einstein's theory let take a case:-
    Mr.X and Mr.Y are two friends. They have two identical dolls which can move at the same speed of 5m/minute. Now Mr.X goes in space at a speed of 0.5C with respect to Earth while Mr.Y stay on Earth. After some time Mr.Y, who is on Earth,starts his doll to run. Mr.Y measures the speed of doll equal to 5m/minute. What will be the speed of same doll measured by Mr.X ?
    Similarly after some time Mr.X, who is in spacecraft, starts his doll. What will be the speed of doll measured by Mr.X and Mr.Y respectively ?
  4. John Jaksich
    John Jaksich
    Their relative velocity is c--the speed of light---the speed of light is not additive as velocities are taken to be in Galilean relativity--

    I am unsure ---at this point--if I remember correctly---at about 0.5 to 0.6 the Einsteinian relativity is more likely to come into play--what can you say about this, yourself? I don't quite know?
    I think, speed of any particle/body, measured from any frame of reference should be same.
    Speed = Length/Time
    At any relative velocity of two frames, the length contraction and time dilation of one frame measured from other frame are in the same ratio.
    Length becomes L=L0*√(1-v2/c2) and Time becomes T=T0/√(1-v2/c2). So speed will be same.
    T=time duration for other frame, T0=time duration in it's own frame.
  6. John Jaksich
    John Jaksich
    That sounds OK to me---but based on your original supposition--the postulates of Relativity may give a different picture--I will have to check my personal references----and I will get back to you---
  7. John Jaksich
    John Jaksich

    From what I understand of "Einstein's Relativity"

    I do not know what to say----and that is because I don't understand you very well---it is the language barrier that I am embarrassed to admit to!

    But, I, like many others only can understand the very basics of "Relativity" ---

    liight--2.99 E +8 m/s --speed of light

    The speed of light is a limiting law

    The speed of an object moving a "relativistic" speeds is measured the same by any reference frame

    The laws of physics are same throughout the Universe


    According to the example painted by you---it sounds like a twin paradox----only with inanimate objects.---

    I must confess that my own personal ignorance is more than I would like to admit to----
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