“Now” (split from Topic 4: Special Relativity)

[FreeWill]

4 hours ago, swansont said:

everyone in a frame can agree that an event that happened at some value of t happened at that time. It is the same time everywhere in a given frame.

Does this mean that there is a common moment of Now (the present) i.e time is ticking everywhere where space is.

 

[swansont]

1 hour ago, FreeWill said:

Does this mean that there is a common moment of Now (the present) i.e time is ticking everywhere where space is.

“Now” isn’t really used, as physics tends to quantify things, but since clocks in different frames can’t be synchronized, the answer is no. There is no common now. Relativity completely discards that concept.

[FreeWill]

19 hours ago, swansont said:

clocks in different frames can’t be synchronized, 

Why not if I am aware all of the involved frames?

[Ghideon]

10 minutes ago, FreeWill said:

Why not if I am aware all of the involved frames?

Consequence of theory of relativity; better handled in a separate thread I think.

Edited June 18, 2019 by Ghideon
Clarified the post

[swansont]

2 hours ago, FreeWill said:

Why not if I am aware all of the involved frames?

Synchronized means both the frequency and the phase (time) are the same for the clocks. But identical clocks in different frames run at different frequencies. They can’t be synchronized.

[md65536]

On 6/18/2019 at 11:36 AM, FreeWill said:

Why not if I am aware all of the involved frames?

Because not all of the frames will agree on the simultaneity of events.

You definitely can define a "now" and you can do it however you want to (a foliation of spacetime would make sensible instants of time throughout space, but the problem is you can foliate it in many different ways, so essentially your "now" would be completely arbitrary).

To be useful, you would want to be able to say that all the events in your "now" are simultaneous. Someone in a different inertial frame would not agree that those events are simultaneous, and would have no reason to accept your personal definition of "now".

[iNow]

I know this is a physics thread, but another interesting idea to consider is how even your own personal version of “now” is actually an amalgam of various inputs and activation pattens from the past.

From the “frame of reference” of your conscious self (whatever that might mean), you’re never fully in the present since your always catching up with neural activity that’s already previously happened in other regions of the brain.

Our perception of time is extremely dynamic and susceptible to change, and it’s easy to achieve with minor changes in things like adrenaline, oxytocin, and (while I’m not advocating this) even psychotropics. 

Apologies for the temporary off topic add. 

Please let’s open a new thread in the proper area if further exploration of this tangent is desired. 

Edited June 19, 2019 by iNow

[FreeWill]

I think to answer the question first we would have to answer: did time start? (I think so)

or Time is infinite? (than why the forward pointing function and the measurable information i.e why/how would time tick if it has no start?) 

[Strange]

58 minutes ago, FreeWill said:

I think to answer the question first we would have to answer: did time start? (I think so)

We don't need to answer that first. Your question has already been answered.

We don't know if time had a beginning (there is no evidence to base such a decision on) and it makes no difference.

Quote

 or Time is infinite? (than why the forward pointing function and the measurable information i.e why/how would time tick if it has no start?) 

Time could be infinite, even if it had a start. Or it might be finite. Again, it makes no difference to the answer to your question.