Did time begin from big bang?
If not then what existed before big bang?
If time had a beginning, then does it have a end, or pause because if time had a pause then we would not have known about it, nor there would be any proof for it so does it happen?
This paper explains the importance of physical mechanisms existing which can function as clocks at various eras. Your question is not simple
Abstract We provide a discussion of some main ideas in our project about the physical foundation of the time concept in cosmology. It is standard to point to the Planck scale (located at ∼ 10−43 seconds after a fictitious “Big Bang” point) as a limit for how far back we may extrapolate the standard cosmological model. In our work we have suggested that there are several other (physically motivated) interesting limits – located at least thirty orders of magnitude before the Planck time – where the physical basis of the cosmological model and its time concept is progressively weakened.
As a completely speculative answer, I would say:
1) According to our current theories OUR time did start with the bigbang. I say our time, because it is plausible to think of other parallel universes with their own laws and times. Not even so, but no law forbids that other universes have more than one time dimension.
2) You have two possible answers, either the nothingness, no time no space no nothing. Or a pre bigbang universe with its own concept of time. One way to imagine this is to think that you create a very advanced simulation in a computer in which intelligent beings populate the virtual world. Time for them is not the same as time for us. For them their time (that for us can run a different rates if we want, or even stop the simulation and resume it later) is not our time. Their time will start at some point and our time will be equivalent (not the same, as the analogy is loose) to the pre bigbang universe.
3) Time can or cannot have an end, having a beginning does not logically imply it will have an end. However, as with the computer simulation, time can pause or have different rates as measured by an "external" observer outside our universe, but there is no way we could detect that, much less find a proof, as for us time runs always at the same pace.
Actually , time is not absolute ... Newton first had stated that time is aboslute (i.e. it was there forever , even before big bang) . But by his theory of relativity , state that it was relative . But he didn't mean to say that it started before bigbang , instead he tried to say that time could be interfered or altered by some ways which can include too much of speed or gravity . You can find more info on this topic at my website :- https://www.allabout4d.wordpress.com Have a nice day and thank you !!!