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Although equations of physics do not prohibit the backward arrow of time but the movement is arrested by the law of entropy...which makes the backward movement of time less likely but it is not totally ruled out. Apart from Entropy is there any other reason for why time can not run backwards?

I guess this question different from other questions as it is not about time travel.Here I interested in knowing whether it is possible to run the history of Universe backwards...i.e. Is absolute backward time movement possible? For example is it possible to reach big bang and before, if there is any, if time starts moving backwards now? I guess one consequence of such a movement will be vanishing of time itself as it reaches plank's region of quantum physics.

Qmechanic
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Dheeraj Verma
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    Not only can time not "run backward"; it also can't "run forward", any more than space can "run leftward" or "run rightward". – WillO Apr 03 '17 at 12:58
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    Possible duplicate of Is time travel possible? Is it possible to go back in time? – Alex Robinson Apr 03 '17 at 13:18
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    @WillO time is empirically different from the spatial directions in that it does have a requisite "direction" to it (at least as far as all our observations go). This is what is meant by "running forward", which does thus have a very clear and concrete meaning that is firmly established and discusses in the literature. I think your response is not only pedantic, but unfounded. – DilithiumMatrix Apr 03 '17 at 13:56
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    I am voting to close as unclear. What do you mean by "time running backwards?" See What is time, does it flow, and if so what defines its direction? – sammy gerbil Apr 03 '17 at 14:42
  • @DilithiumMatrix: The fact that we can distinguish one direction of time from another does not mean that time "runs". If the preferred direction is, say, "away from the Big Bang", then the only way I can see to make sense of the question "Can time run backward?" is to interpret it as "Can a movement toward the Big Bang be a movement away from the Big Bang?", which both removes the reference to running and makes the answer pretty obvious. (Also -- we can choose a preferred direction for time, but can just as easily choose a preferred orientation for space. Space still doesn't run.) – WillO Apr 03 '17 at 15:05
  • The history of events which constitute our Universe have a sense of time and direction.Is it possible to define a Universe in which the events occur in the reverse order of events as defined in our Universe? If possible then that would be time running backwards. – Dheeraj Verma Apr 03 '17 at 15:09
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    What does "occur in the reverse order" mean? The order is defined in terms of the sequence of events. I define the direction of time to be such that breakfast comes before lunch. Is it possible to change the definition so that lunch comes before breakfast? Sure, but that's just wordplay. Is it possible for lunch to come before breakfast given the definition of "order" that requires breakfast to come before lunch? Of course not. What more could there possibly be to say? – WillO Apr 03 '17 at 15:16

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If it does we will never know. Our perception of time passing is based on known past and unknown future. We exist in that instant between the two. We're events being reversed, we would loose events but still recall prior events and still have an unknown future. Our perspective is what gives time direction and as scientists are beginning to realize, our perspective is vastly different from actual reality.

zane scheepers
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    "and as scientists are beginning to realize, our perspective is vastly different from actual reality." I think this has been at very least widely speculated in philosophy for a long time. It's not like a new discovery or anything, just reaffirmation that physics is based entirely on how we perceive things (and to some level will always have to be). – JMac Apr 03 '17 at 13:40