Einstein’s Relativity : Einstein’s Relativity Hello every body
Today we learn something about Einstein’s Relativity. We will only deal with concepts of relativity, some formulae and some of its proof.
We will avoid mathematical calculations as possible
Points we will be discussed : 1 Einstein’s postulate of relativity
2 Galilian transformation equations
3 Einstein’s transformation equations
4 concept of simultaneity
5 time dilation
6 length contraction Points we will be discussed
Einstein’s postulates : Michelson Morley experiment
Postulates
1 all the physical laws must retain same forms after transformation from one frame to another
2 speed of light remains same for all observer with respect to all frame of references Einstein’s postulates
Slide 4 : now as per the transformation equation given by newtonian mechanics
X’= x - v1t (for distance)
v’ = v - v1 (for velocity)
A 60 km / hr
B observer 50 km / hr
This equations are derived considering the fact that time interval between two event remains same for all observer
Slide 5 : Now equation simultaneous in one event can not be simultaneous in other event.
For e.g.
A C B
Consider one train moving with some velocity towards right . Initially it is at rest . two observers are there at point C one sitting inside the train and other outside the train. C is midpoint of AB
Now two flashes are made at A and B simultaneouslu . Since the train is stationary both the observer see the flashes at same time since light take same time to travel from BC and AC. So they conclude that both the flashes are made simultaneously
Slide 6 : So the time for each observer will be different according to frame of reference.
There fore galilian transformation equation has to corrected.
Drawback of galilian transformation equation in terms of transforming law of
Electrodynamics
Success of Lorenz transformation equation in transforming law of electrodynamics.
Einstein’s comment on laws of Newtonian mechanics “ ‘laws of Newtonian mechanics has to be revised.
Slide 7 : Newtonian transformation equation
x’ =
t’ =