Before we start today’s VERITAS there is a thought I wish to share with you . I read this somewhere( I dont remember where) : When we read philosophy , religion , poetry , literature etc we usually read the author’s orignal works . For example if you want to read Socrates’ philosophy you would have to read SOcrates or Plato(his pupil ) . If you wish to read Kant’s philosophy or Vivekananda’s thoughts you would have to read their orignal/translated works . Now on the other hand when you read Science you rarely read the orignal works … None of us have read Newton ‘s Principia Mathematica to understand his laws . None of us have read Darwin ‘s book to understand his evolution theory . The reason is that when Science comes to us it comes as the KNowledge of the present times .
The Orignal works are applied , changed and modified and then the theory is taught to us . Science is Knowledge . Philosoply(or similar subjects ) are more of viewpoints of people which cannot be modified and rarely improved .
Now for Todays VERITAS : Einstein’s special theory of relativity changed our understanding of space and time and made some exciting predictions of how things behave when they move close to the speed of light . To take an example : time moves slower in a body moving close to the speed of light . The faster the body moves the slower time flows in its reference frame . People were so excited about these implications of the ralativity theory that they thought of various paradoxes . Now in Physics there is no paradox . There might be two different ways of looking at a problem and these different ways may yield different results . But if these two viewpoints yield different results then one of them has to be wrong . Physics has no room for paradoxes .
The most famous “paradox” was the twin paradox . Imagine two twins who decide to part ways . One of them ( say A ) sits in a rocket and blasts off into space . The other twin( say B ) stays on earth ( being more interested in seeking earthly pleasures ) . The rocket carrying A reaches fantastic speeds ( close to speed of light ) .
50 earth years later A decides to visit earth . The age of the twin B has advanced by 50 years . But to B’s surprise A is only 7 years older .
Wow ! The reason is simple …. A moved close to the speed of light so time was slower in his reference frame and so he aged slower .
The “paradox” is this . If we take B’s point of view then A was moving at close to the speed of light so he should be younger . ANd the explanation we have given above is valid .But if you take A’s viewpoint then B was moving close to the speed of light ( the reference frames are relative . There is no absolute motion ) . So B says that A should be younger and A says that B should be younger . Who is correct ? who is younger ? This looks like a perfectly symmetric argument and it looks like a paradox .
How do we resolve the paradox ? The solution is this : One of the viewpoints is wrong. What we have to understand is that Einstein’s special theory of relativity is valid only for bodies moving at constant velocities . Accelerated frames of reference are not the correct ones . So if B and A keep moving forever(and dont ever meet ) then both the viewpoints are correct . But the symmetry is broken when B decides to meet A . At that time he has to come back to earth . He has to change his direction of motion ( from away from earth to towards earth ) .
And this is accelaration . So his frame of reference is not valid .
The twin B has to be younger than A . The acceleration , the comparison breaks the symmetry of the 2 arguments and makes the earth frame of reference valid . There is no paradox.
