3

Space-time is thought to curve and ripple. Is a kind of metatime required in or during which such events take place?

Urb
  • 2,608
user55571
  • 25

2 Answers2

2

Space-time is thought to curve and ripple.

Space-time, i.e. the set of all events under consideration (specificly: coincidence events), together with all relations between these events (primarily: by listing who, among all principal identifiable participants, took part any one coincident event), is thought to be not necessarily homogenous and/or isotropic by definition, but (possibly) to consist of distinct regions which (may) differ in terms of suitable measures, such as curvature.

Is a kind of metatime required in or during which such [differences and distinctions] take place?

No: at least some measures of (possible) differences are defined intrinsically, appealing only to participants and the coincidence events in which they took part. Some examples are sketched

Community
  • 1
user12262
  • 4,258
  • 17
  • 40
0

This is an open problem, the problem of Time in General Relativity and Quantum Gravity (e.g here and here).

The solution would require a (radical) synthesis of General Relativiy, Quantum Field Theory and especially Thermodynamics (the 2nd Law).

Many people, due to the treatment of time parameter in general relativity (general covariance principle), take a stance that (flow of) time is an illusion (sth this author does not agree with).

Another approach is to interpret the time parameter in General (and Special) Relativity as duration time and not as event instant time, this provides a workaround for many cases.

Furthermore work by Prigogine and others has shown that in non-linear systems one can define a unique Liouville-type operator which is not-time symmetric and which can define a (new) unique time-parameter for the dynamic evolution of the system (Prigogine's lecture on the Nobel prize).

The problem of time in physics and chemistry is closely related to the formulation of the second law of thermodynamics. Therefore another possible title of this lecture could have been: “the macroscopic and microscopic aspects of the second law of thermodynamics”. It is a remarkable fact that the second law of thermodynamics has played in the history of science a fundamental role far beyond its original scope.

Suffice it to mention Boltzmann’s work on kinetic theory, Planck’s discovery of quantum theory or Einstein’s theory of spontaneous emission, which were all based on the second law of thermodynamics.

Urb
  • 2,608
Nikos M.
  • 5,142
  • 1
    Nikos, isn't it obvious that time is not a "point", just like distance is not a point? Still, it seems the problem of time required for the space(time) to change boils down to the question: what is the speed of gravity? Here is an interesting answer: http://physics.stackexchange.com/a/5502/43402 – bright magus Jul 17 '14 at 21:28
  • @brightmagus, nice link, but the problem of time is more than the velocity of gravity and in the final analysis is a problem in whole physics theories (not just gravity). It manifests in gravity due to general covariance principle in space-time, but it is still there anyway – Nikos M. Jul 17 '14 at 21:33
  • @brightmagus, however if that is what the OP asks for, i would add this as an answer or a comment to the answer (if i were you). i think the OP asks sth a bit more general but the OP will decide for himself – Nikos M. Jul 17 '14 at 21:40
  • OK, there are two ways to establish the time the OP is asking about. Either we need first to understand the mechanism of space(time) change (how is the change occurring exactly, what is changing and how), and then verify it empirically, or simply conduct some experiment to get the number only (without understanding). The link I gave speaks of the attempts to measure the speed of gravity, and if gravity is curvature, then measuring its speed should give us (some) answer as to the time needed for this change to occur. (True, the OP was not very specific.) – bright magus Jul 17 '14 at 21:40
  • Hi @NikosM., several links in your answer are dead now. – Urb Sep 04 '21 at 17:48
  • @Urb, updated all links I could find, except one – Nikos M. Sep 05 '21 at 06:21
  • @NikosM., thanks. I've updated the missing link with the copy archived by the Wayback Machine. – Urb Sep 05 '21 at 07:39
  • @Urb, why the downvote? – Nikos M. Sep 05 '21 at 07:58
  • The downvote's not mine. The edits have caused this question to be on the homepage now, so it may have attracted views from other users. – Urb Sep 05 '21 at 08:17