Past present and future
Literally these three are the building blocks of human’s thought on time. Humans divided time into these three categories,on behalf of what they think they are feeling. These three terminologies are far more fictions than reality for science to accept. Even Science have always used such terms to beautify the concepts of imaginations.
Modern science measures time as per the universal constant of light velocity. The fact is, the term ‘universal’ is actually wrong. Light’s velocity if constant and maximum only a particular region. Velocity of light could be different in different areas of the universe; sometime more than it. The real fact is,we won’t be ever be able to see them within our observable limit. For us the Special Relativity hold everything.
People often gets mislead by the ideas of Special Relativity,even the Physics students. The postulates only states about the existence of physical laws and light’s maximal constant speed within the observers inertial frame. One of the biggest misinterpretation is Light’s speed is maximum about 300 million metres per second. I love to mention that,not only light but its the same for every electromagnetic radiations.
We can assume the first postulate to be a generalisation of Galilean principle of relativity – which is the First Relativity theory in Physics,made to apply for every physical phenomenon in all inertial frames. Remember : INERTIAL FRAMES.
While the second postulate is clearly stating that the velocity of light in vacuum is independent of its source as well as its direction. We can also interpret that the velocity light in vacuum is same in all inertial reference frames.
The notion of ‘same’ later was changed as constant – which is true (but not really in every aspects)
When Maxwell formulated the electromagnetic waves,he found the relations which was used to relate ,compare and confirm – light was also an electromagnetic wave, hence it has the velocity of 300 million metre per second like every other electromagnetic radiations.
The concept of INERTIAL FRAME is what everyone neglects – which ultimately creates the biggest misinterpretations in relativity.
Inertial frames are just the frames which obeys newton’s laws (simple concept)
There are enough frames other than this inertial one. For example- an accelerating frame. Special relativity is invalid there.
So what? Light could have different speed there. May be every notion of time,which we have defined may have been being violated there.
But who cares?
We don’t want to care about it. Because,we are never going to observe anything outside our observational inertial frames. Or clearly, we can never ever know what’s happening in an accelerating frame,unless we are inside or nearby it – which makes it an inertial frame for us,again.
So within the inertial limit,we don’t have to worry about anything outside Special relativity, but there are places in universe,far far from us , where we time might be different, Special relativity might be getting violated – but who cares?
As we won’t ever have to observe it,we dint have to bother. Neither do universe.
Basically,this was the reason why Albert Einstein searched for a new GENERAL RELATIVITY THEORY.
In short, I can say “Special Relativity is a local concept, while General relativity is the Global (in the sense universal) concept.
Hence, past present and future terms are only valid inside our inertial frames. They aren’t universal. It’s not good to use them for anything considered universal or large.