Is time real (in a physical sense)?

[dendros]

As in, is it a physical quantity/parameter like mass or is it a descriptive name that we give to the flow of dynamic processes?

This is not a theory or idea, just a question that I feel compelled to ask after reading an article that claims that a study shows that time travel would be possible under certain circumstances although it would not be possible to change the present by traveling in the past.

And I feel compelled to ask this because if time is not a physical quantity but a label for describing dynamic processes then traveling in the past, for example, would mean basically reversing all physical processes to a previous state, like a previous snapshot of the physical reality including reviving dead persons that were alive in the past (but not in present) and so on. And not only this but also the entire Universe must revert to a previous state for time travel in the past to be possible.

I hope I didn't break any rules by asking this, I'm really curious about that.

 

[russ_watters]

[Moved to other physics]

As in, is it a physical quantity/parameter like mass or is it a descriptive name that we give to the flow of dynamic processes?

Use of the word "real" here is problematic to me, because why shouldn't what happens to an object be real? But yes, time is part of the description of what happens to an object, not an inherent parameter of the object itself. Like velocity or location/displacement.

 

[dendros]

Then I should clarify: by "real" I was asking if time is a physical "object" like a field, body, etc or a just a description. If it's just a description then time travel would imply what I described in the OP but of course I'm not sure so that's why I opened this topic.

 

[Klystron]

As in, is it a physical quantity/parameter like mass or is it a descriptive name that we give to the flow of dynamic processes?

Time is a physical quantity measured by clocks in SI units seconds.

Time also describes interval between events, duration and sequence of events.

Thus, your question exposes no dichotomy but does illustrate the fascinating nature of the subject. Humans appear to experience time and can directly measure interval by monitoring our heartbeats, close to a second apart.

Time fields, time flow and the "arrow of time" metaphor remain sources of lively discussion. (Search PF threads with these keywords, if interested.) Presumably one could employ a mathematics that treats time as a field. Difficult to avoid circularity defining a realistic time flow, given the definition of velocity mentioned in an earlier post.