Space and Time

The real revolution in Physics started with Albert Einstein's Special Theory of Relativity. the most of important point of which was that speed of Light remained constant however fast you may be moving , wherever you were in universe. It had stunning effects. Thus the only thing that happened when light came from a object that was receding from us was increase of its wavelength.


One of its implication was that if a spacecraft travels very fast , say at 99.9% of speed of Light , still light would seem to travel at 300,000 KM/s . The energy we spend in further increasing its speed starts going into increasing your mass by E=mc2 . But the craft itself doesnt feel any added weight , it instead feels length to contract . So at the speed 99.9%of light it will feel sun to be at mere 4 million miles and would complete the round trip in 44 seconds. But to the observer at earth it would be more than 16 minutes . So apparently the craft has landed in its future.This is the conecpt for Time Travel but practically the energy needed to power the craft could power our present technology for more than a million years .


This concept brought a view of world as 4 dimensional structure with 3 dimension of space and 1 dimension of time.And it thus brought about 2 concepts of time . one is in which we are static and time is flowing by. Another is in which all events are already present . It is us who are moving through those events.


Another implication of Einstein's theory was curving/elasticity of spacetime.First possibilty is that When light encounters a very dense material it is deflected due to gravity and thus
produces a dialation of time. Thus it implies that near a object which has mass of sun and radius of a few miles , the dialation is so huge that time comes to almost a halt. A few microseconds in that time would be more than few billion years to us. Example os such objects are Black Holes . Also there are Binary stars composed of neutron which are highly dense.Second possibilty is due to space shrinking or exapnding . It has been measured that our universe is expanding continiously wit each galaxy moving apart from all others.


Thus these concepts were the basis of remarkable change in view of space and time.