13 Jun '13 09:03>
Does "now" have a beginning and end?
Kelly
Kelly
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?
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
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
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.
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).