The Dark Side of Time

Advances in the investigation of the physical universe we live in.
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YMix
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Re: The Dark Side of Time

Post by YMix »

“There are a lot of killers. We’ve got a lot of killers. What, do you think our country’s so innocent? Take a look at what we’ve done, too.” - Donald J. Trump, President of the USA
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Parodite
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Re: The Dark Side of Time

Post by Parodite »

Interesting, thanks. Quick read through some of it.

Want to write down more about time and stuff related, but I get a writers block when I want to start :shock: So maybe I'll just write down notes here for the moment, bit randomly as they pop up. From there maybe one day write something coherent with a head and a tail even.

Dimensions of space and time are mathematical abstractions, and belong to the experiential 4D model of the world with us in it that arises in our brains. The fact that our brains create this 4D model seems to me as important, relevant and as interesting as modeling the universe as it is/may be independent from our brains and 4D experiential interface (the question of objective reality)

In pure physical terms, time refers to the relative speed with which processes occur. For instance, relative to a cesium clock on earth.. a cesium clock at high altitude in stationary orbit around the earth runs faster due to gravitational red shift. So when we say that "time goes faster" in the cesium clock in higher orbit, what is actually meant is that processes can speed up or speed down relative to each other depending on their distance from a shared source of gravitation, and/or their relative speed (acceleration or deceleration). The use of "time" as an abstraction here, is therefore a bit tricky and misleading.

Typically past and future (the passage of time), but also here and over there (space) are a model emerging in the brain. The linearity of experiential time easily agrees with the laws of thermodynamics: processes occur one way only. To go back to the past is as much an oxymoron as trying to reverse a process like a glass that fell to pieces. In terms of experiential space this is less obvious however: it appears we can go back and forth in space..depart from location a) and return later to same location a). But this is obviously false! "Location a" is changing continuously in every matter and sense. So the linearity of space can safely join the linearity of time, and both stay in agreement with the laws of thermodynamics.

Claims are made however that in the magical world of quantum mechanics "things are reversible".. according the equations that is. It is nonsense. There is more cheap lingo that suggests certain things for which there no reasonable argument, no coherent theory, and never an experiment to prove it. Fantasies. For instance, the delusion of "sameness" as I would frame it. "A particle can be present at two places at the same time" and more some such. Just semantic pompous voodoo.

The vacuum... "empty space" is no longer considered empty (in the sense of literally "nothing") by any serious physicist. Makes sense. Things can be distinguished, but not separated creating some literal "nothing" between them. But this brings back the question of how fields (+waves) "propagate in space time". Can light waves for instance do without a medium? If not, what type of medium is that? Supposedly it is the structure of spacetime itself. (will provide links to some interesting articles about the structure of spacetime by theoretical physicists who know their stuff)

I find concepts like "information" but even "entropy" inadequate to capture as closely as possible the nature of reality, of the cosmos, of all scales from the smallest to the largest. Particles, fields, gravity, the structure of the vacuum, the micro the macro.. I would just stick to thermodynamics and translate everything ultimately in terms of energy.

ADD: About probability in quantum mechanics and predicting the past

Probability distributions, probability waves, are concepts used in quantum mechanics. Are they physical realities or human statistical abstractions due to ignorance, albeit very precise guesswork? Einstein considered QM incomplete because it does not provide with it a physics that explains why quantum systems follow the discovered rules. They "have no sources" so to speak. For this reason, some physicists proposed the idea of "hidden variables" but they never got very far. The reason may be simple and the answer staring you in the face: "probability waves/distribution" concerns things that haven't happened yet, as opposed to things that did happen already. Let me dig that one out.

Predicting the past. In classical physics it is taken for granted that there is loads of physics available where many variables can predict a future outcome of something when you do the calc. However, we never predict the future; in actuality we always predict the past. We don't predict what will happen, but what will have happened.

Sounds like an irrelevant play of words, but me thinks it isn't. In classical physics events that happened already were put on a time line (i.e. you do observations) and connect those events after plotting them on a timeline by analyzing them and and then derive the equations that connect the dots mathematically. You can then use those equations to predict the future.. is the general view. But you in fact don't predict the future, you predict the next past.. which when added to the timeline still conforms to the physics that "describes and predicts order of events". But, as said, it only represents events that have already happened. It would term this "the causal past" or something like that.

The causal past of course, when considered, strongly suggests a causal deterministic sort of physics. A causes B causes C etc. Rephrased, "event B always has its sources in the past", as for instance event A (a condition, force variable configuration whatever) that took part in the equation. When more random and complex events are plotted in the timeline of the past, you get causal indeterminism. Statistics then kicks in as a handy tool. But both causal determinism and causal indeterminism concern themselves with predicting the past. Causes and sources plenty to choose from; just look at the time line of all that happened in the past and draw your conclusions

Now the point of the above is, that it only works for as long as what you measure is similar enough before and after the measurement. The moon today is not the same moon anymore tomorrow.. or even the next second.. but it doesn't matter. It is similar enough to predict and say where the moon will be tomorrow at any given moment, and precise enough for that calc to work fine. In the same way, you can recognize somebody today, because s/he is similar enough to the one you saw last week. Your observation/measurement, will not mess up the situation much, you can rely on past experiences.

On the micro scale of quantum mechanics however, the above changed dramatically because the act of measurement changes the thing you hoped to measure. In other words, you have no time line of the past available with plotted observations that can serve as a causal source from which you can explain the actual observation. Uncertainty of what are momentum and location of a particle (as per Heisenberg's uncertainty principle) kicks in here as well. The causal past, as a source of information, simply cannot be plotted anymore in quantum mechanics. So all you are left with, is predicting a future without a past to back it up.

This may appear weird, but it is actually less weird when you think about it. After all.. the causal (deterministic and indeterministic) past in classical physics, represents approximations within a limited domain of validity, where observed objects are unaffected enough by measurement and remain similar enough when times goes by to be plotted on the time line of the past. In the quantum world this luxury disappeared, mainly due to the practical limit.

When the past stops being available as a source to produce a causal mechanistic framework... all you are left with is probability. On closer inspection though.. classical/causal physics is also a form of statistical probability mechanics, but less obvious at first sight.

Err.. it still became a long rant. :o Probability distributions are weird animals.

add: The problem of how to interpret probability in QM goes back to the 30 year disagreement between Einstein and Bohr.

Related links of interest:

Revisiting the Einstein-Bohr Dialogue.

Bayesian Probability Theory and Quantum Mechanics

Interpretations of Probability

I'll concoct my own interpretation later.

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Julian Barbour, visiting professor at the University of Oxford and the author of The End of Time, addresses the question, Does Time Exist? Barbour explores the history of scientific thought on the concept of time and presents his own interpretations of what time is.
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