Talk:Time in physics
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(William M. Connolley 22:01, 10 Jun 2005 (UTC)) This article is weird. Most of it is about the history of time in physics (which is how it started off) which is splendid stuff but really belongs in an article called... history of time in physics. Some of it (eg the lagrangian stuff) appears to be "some equations which have time in them" and I can't see the point. Charles, this is all your fault :-)
Perhaps it should be called "the history of time in physics", but then again the subject of what time has meant to physicists has changed over time. The reason for this is because just thinking about time one can come to so many conclusions. And the issue of the physics tied in with the philosophy of time has not even been suggested by the title. For anyone too impatient to wait for the cleanup I suggest reading "Time" by Craig Callendar. Dessydes 16:34, 19 May 2006 (UTC)
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[edit] To the reader
Time is a fundamental subject in physics which has taken thousands of years to understand and master. In distinction to Space, which is obvious to our eyes, it took some technological developments to make the subject of Time easier, and we are not yet done with the subject.
If you do not understand part of the article, just let it pass; your mind will return to that which you did not understand, if you are still interested, and you have prepared yourself for the next encounter.
[edit] Time in computational physics
I left this section alone, during the rewrite. Does it make sense to delete it? It is covered in a previous sentence of the article: time is a parameter in physical models Ancheta Wis 10:25, 1 February 2007 (UTC)
[edit] To the editors
I have retained the cleanup notice; it sits at the foot of the article. If the community deems it fit, we can then remove the notice, in time. Removed the tag as a bot got hold of it. --Ancheta Wis 18:36, 6 January 2007 (UTC)
[edit] The physics of a conversation
Since working on the cleanup, I realize that I have never seen research on the physics of a conversation. What I mean is that the world line of a system can be known, but what about two intercommunicating systems? Are world lines doomed never to interact, except thru dynamical influences? The closest thing to this I know about is A Mathematical Theory of Communication which embodies encoding and therefore protocol, but I would appreciate a citation for a basic, from the ground-up, analysis. --Ancheta Wis 14:40, 10 September 2006 (UTC)
- See Rudolph Carnap (May 1957) Chapter G (sections 48-51: pages 197-212), "Axiom Systems of Physics", Introduction to Symbolic Logic and its Applications, a translation by William H. Meyer and John Wilkinson of Carnap's January 1954 Einführung in die symbolische Logik.
- Carnap utilizes the concept of a signal line which finesses the need for contiguity of world lines, but which instead allows for a signal chain between world points.
- Ancheta Wis 19:04, 25 December 2006 (UTC)
[edit] why time causes paradoxes in physics
Math is a highly compressed language that seeks to symbolize experiences in a very precise way. In many calculations time is treated as an abstract term, just a number, and detatched from the experience that is beyond the symbol, namely a cycling countable event. because of this detatchment, silly notions like backwards in time and time travel can arise. It is not so easy to make time into a negative if you see it for what it is, namely some perceived stable event that one can use as a gauge for other less orderly events. Speed is Distance/time, but this gets all hairy in relativity where its not so nice and neat as the mass of the object and its speed begins to effect the time factor, which mathematically seems to go negative beyond light speed...but of course that is only because the numbers have lost their connection to the events they are symbolizing.Jiohdi 21:44, 5 February 2007 (UTC)
I will get more concrete and refer to John Cramer [http://seattlepi.nwsource.com/local/292378_timeguy15.html is preparing an experiment] to determine whether quantum entanglement is also nonlocal in time as it is in space. This can also be stated as 'sending a signal back in time'. The experiment is still in preparation as of 10:57, 16 November 2006 (UTC).
Eckard Blumschein [1] claims that there is no signal back in time but perhaps just a mistake. E. Schroedinger wrote in 'Quantisierung als Eigenwertproblem', 4th Mitt. in Ann. Phys. (4)81, 109ff (1926), p. 112, 'one may consider, if nessessary, the real part of psi the real wave function". He omitted the aspect of required apparent symmetry. Only positive elapsed time can be measured. Our usual time scale is bound to an arbitrarily chosen event. It has been abstracted and extrapolated from elapsed time which is bound to a real object. This abstraction replaces one-sided integral relationships by differential equations. Pertaining time-symmetry requires exclusion of the unphysical advanced part of solution in order to obey causality: Future quantities cannot influence current processes being causally embedded into the integral effect of past influences. Invariance against shift and even reversal of time reversal is only possible at the level of abstracted usual time.
Since time and frequency are related to each other via complex Fourier transform, function of either time or frequency must exhibit Hermitean symmetry, i.e. positive as well as 'unphysical' negative arguments. Fictitious negative elapsed time is required as to encode merely positive frequency chosen by Schroedinger and also by Dirac. Weyl did not understand this in 1931. He wondered about PCT-symmetry.
One has to humbly accept that both imaginary and apparently negative quantities are the tribute one has to pay for abstraction into IR anstead IR+ and use of complex calculus. Apparent symmetries must be interpreted as unreal. They would disappear with correct inverse transform as do imaginary quantities, too. Blumschein 17:22, 5 March 2007 (UTC)
- Your paper suggests an experiment based on Cramer. Cramer might try dumping energy into both future and past. Your paper suggests all the energy will wind up in either the past or the future, and not in both directions. But this would require careful accounting of the energy in each pulse which he is transmitting. --Ancheta Wis 19:17, 5 March 2007 (UTC)
Do not get me wrong. I just picked up Cramer's idea as an example of ignored essentials. Nobody can analyze future data. They simply do not yet exist. While past events are evident from left traces, future events are only predictions, no matter whether they will come true or not. Albert Einstein wrote: 'For us believing physicists, the division into past, present and future has merely the meaning of an albeit obstinate illusion.' I do not see any reason to share this belief with him, Newton, Minkowski, Hamel, Hilbert, Noether and many others. At least there is no doubt: While past is unchangeable, future is uncertain. All measurable reality exclusively belongs to the past. It makes a serious difference whether one deals with abstract time as did A. E. and John Cramer or with reality-bound elapsed time. I am pointing my finger squarely to most serious consequences of the neglect of this essential difference between abstract time in IR and concrete elapsed time in IR+. While obviously nobody can go back in elapsed time, mainstream physics and technology do not yet understand the implications for signal processing and quantum mechanics, including fourfold redundancy, non-causality, arbitrariness, and misinterpretation of apparent symmetry. Blumschein 07:07, 6 March 2007 (UTC)
