1) Principle of relativity:
The laws of physics are same in all inertial frames of reference.
2) The constancy of the speed of light:
Speed of light in free space(vacum) is constant(has same value c) in all
inertial frames of reference.
observer B is moving away from A at a speed of c/4, then Galiliean kinematics predicts that B
measures the c-c/4=3c/4 for the speed of light emitted by A. If the observer C is moving towards A
with a speed of c/4, then the Galilean kinematics predicts that C measures the value c+c/4=5c/4 for
the speed of light emitted by A.
and confusion which must be solved in future.
1) Time Dilation:
between the two events in this frame let it be t0 . This is called proper time. If the observer is moving
with velocity v with respect to frame of events, then the time measured by observer would not be it
will be t0
same for all. It is different for diffferent persons.
(Chap.29, Surah Al-Maarij 70:4)
equivalent to a thousand years in the way you count" (Al-Quran 22:47)
spaceship is t. Focus on above two clocks you can see that
2) Length Contraction:
(say 1 meter), which is ℓ0 and called proper length. And if the observer moves with spaceship in a
space then the length measured by the observer will not be 1 meter it will be less than 1 meter, denoted
by ℓ and
observers m0 (say 1kg), called proper mass. Now, if the observer moves at high speed, then the
time maesured by observer will not be 1 kg, it will be greater than 1 kg. denoted by m and