anyone;
I know that, due to the language we use for physics, we define Plancks time as a certain "length" of time which makes it verbally sound very much like it must have a beginning and an end. But that is just because of the language we use.
So does Planck's time literally have a “beginning” and an “end”?
https://en.wikipedia.org/wiki/Planck_time
I honestly don't know. I don't even know if it could make any sense to say that Planck's time “has a beginning and an end” because, if it does make sense, wouldn't that imply that there is a meaningful time period less than Planck's time (which would be a contradiction of Planck's time) else the beginning of a Planck's time happens at the 'same' moment of time as the end (which would also be a contradiction?) of the Planck's time?. But, if it does make sense and Planck's time has a beginning and an end, then isn't “now” always just one Planck's time in temporal length and thus has a “beginning” and an “end”? Anyone?
Originally posted by humyA beginning and end imply boundaries, a single point has no boundary because the boundary of a space has dimension one less than the space it bounds, a point has dimension zero, and there are no spaces (afaik) that have negative dimension.
anyone;
I know that, due to the language we use for physics, we define Plancks time as a certain "length" of time which makes it verbally sound very much like it must have a beginning and an end. But that is just because of the language we use.
So does Planck's time literally have a “beginning” and an “end”?
https://en.wikipedia.org/wiki/Planck_time
...[text shortened]... lanck's time in temporal length and thus has a “beginning” and an “end”? Anyone?
Originally posted by DeepThoughtShould we think of a single Planck's time being a "single point" in time thus without boundaries or a "period of time" thus with boundaries?
A beginning and end imply boundaries, a single point has no boundary because the boundary of a space has dimension one less than the space it bounds, a point has dimension zero, and there are no spaces (afaik) that have negative dimension.
Originally posted by humyThe Planck time is a numbers game. One combines some physical constants and calls it a time. The importance of the Planck time is that it is representative of the scale at which we expect quantum gravity effects to be important. This makes experiment challenging as event horizons proliferate at those scales. If space-time is continuous and there is no shortest distance between two points then my argument above holds. If, as for example Loop Quantum Gravity predicts, space time is essentially discrete, then for a given ideal point-like observer "now" is a discrete point and either has no boundaries or is it's own boundary in which case the beginning and end of now is now.
Should we think of a single Planck's time being a "single point" in time thus without boundaries or a "period of time" thus with boundaries?
As an aside loop quantum gravity involves a step where they compactify the Lorentz group, and then predict discrete states. I'd like to see a convincing argument as to why the discretization of space-time isn't an artifact of the compactification (which may exist - I haven't done a literature review).
I'm not trying to setup a debate I thought it interesting that "now" is so
small if that word can be used to describe it, has some qualities of a
eternal time limit, boundless/boarderless. Of course I may be way off
here....I'll await someone else to show me how they differ in that respect.
Kelly
Originally posted by KellyJayOf course "now" has a beginning and end. There was a time in the past in which the present "now" was not and a time in the future in which the present "now" will no longer be now. So each "now" in time has a beginning and end.
Does "now" have a beginning and end?
Kelly
The Instructor
Originally posted by RJHindsWith "now" isn't the beginning the same as the end?
Of course "now" has a beginning and end. There was a time in the past in which the present "now" was not and a time in the future in which the present "now" will no longer be now. So each "now" in time has a beginning and end.
The Instructor
Kelly
Originally posted by DeepThoughtMathematically, a single point on the number line is a bounded set, with the point being both upper bound and lower bound.
A beginning and end imply boundaries, a single point has no boundary because the boundary of a space has dimension one less than the space it bounds, a point has dimension zero, and there are no spaces (afaik) that have negative dimension.
http://en.wikipedia.org/wiki/Bounded_set
I would say that on the time line, the lower bound corresponds to a beginning and the upper bound to an end, although it must be noted that the bounds are not always members of the set.
Originally posted by DeepThoughtI missed the part of your post where you said, "...a discrete point and either has no boundaries or is it's own boundary in which case the beginning and end of now is now."
The Planck time is a numbers game. One combines some physical constants and calls it a time. The importance of the Planck time is that it is representative of the scale at which we expect quantum gravity effects to be important. This makes experiment challenging as event horizons proliferate at those scales. If space-time is continuous and there is n ...[text shortened]... n artifact of the compactification (which may exist - I haven't done a literature review).
I said it later, not seeing this.
Kelly