[jeffreyH]

time?

Maybe you should print up your thesis and throw it in the bin. It will thank you for putting it out of its misery.

[Bill S]

Actually that is EXACTLY for this thread.

Perhaps I should have said "not yet".  There are some points I need to clarify, in my own mind, first. The most important of those link to https://www.thenakedscientists.com/forum/index.php?topic=76446.0 and possible responses there.

[guest4091]

From Phys.org. Physicists reverse time using quantum computer. https://phys.org/news/2019-03-physicists-reverse-quantum.html

from the article"
"What makes the latter look so absurd is our intuitive understanding of the second law of thermodynamics—an isolated system either remains static or evolves toward a state of chaos rather than order."
There are star and galaxy formations, plant growth, various life forms, continuously occurring organized systems which contradict that understanding.
It's possible to reverse a process without reversing time.

[yor_on]

I agree Phyti. Can't use that one, it's filled with holes.

[guest4091]

From the Phys.org article:
"The physicist explains that the evolution of the electron state is governed by Schrödinger's equation. Although it makes no distinction between the future and the past, the region of space containing the electron will spread out very quickly. That is, the system tends to become more chaotic. The uncertainty of the electron's position is growing."
______________

How does a single object (electron) have an order?
Why is the system of one particle labeled as chaotic because of an uncertain position?
It seems more likely to be lack of knowledge for the observer, than a property of the particle, or any physical process.
_______________
A criminal leaves a crime scene and goes into hiding. A search is started. His possible location expands with time. When a sighting is reported, the search party focuses on a  smaller area.

The example is not about time, but the knowledge of the criminals location.
It's also a random dynamic process with a high degree of unpredictability.

If the 'arrow of time' is a fiction, then their report is fluff.
There were many interesting comments for this article.
______________________
An object, with or without a structure, typically has many positions, if it has extent in space. The earth has all the positions within a sphere of radius 4000 miles. Not one, as  defined by the abstract center of mass. I.e. the position of an object is a volume, not a point.
This is another example of the consequences of excessive abstraction. If time is line representing a dimension, then motion can also occur in time. Then  science should experiment to see if there is a reverse gear!

[mxplxxx (OP)]

Given that energy is derived Planck's Quantum of Action which is a constant, it is possible that time is the only variable in the universe. Everything we see and experience may just be due to variations in time causing variations in the energy/power of objects in the universe.

[mxplxxx (OP)]

Given that energy is derived Planck's Quantum of Action which is a constant, it is possible that time is the only variable in the universe.

I can think of a counterexample, so this isn't true.  The air pressure on this mountain changes with altitude.  That's a variable (altitude) in the universe that isn't time.

Air pressure, related to energy which is determined by time E=h/t.

[mxplxxx (OP)]

Air pressure, related to energy which is determined by time E=h/t.

Wrong formula. E=h/t sounds like a formula for pressure in a leaky tire. The pressure doesn't change over time.  It will still be thinner at the summit tomorrow, even if the weather does make some fluctuations.

The formula is
P=P_b • exp [ -g₀  M (h-h_b)} / (R* T_b)]
where:
P_b = static pressure (Pa)
T_b = temperature (K)
h = height above sea level (m)
h_b = height at bottom of layer b
R* = universal gas constant: 8.3144598 J/mol/K
g₀ = gravitational acceleration: 9.80665 m/s2
M = molar mass of Earth's air: 0.0289644 kg/mol

That's from wiki barometric formula, and it is not a function of time.

E=h/t, the basic equation of quantum physics. Your equation is at a pretty high level, As you dig down, it seems Energy comes into it more and more (e.g  temperature is a function of kinetic energy, see https://www.enotes.com/homework-help/describe-relationship-between-temperature-kinetic-553925.) And according to E=h/t energy is a function of time. 

[mxplxxx (OP)]

I think there exists perceived time, related to awareness

Perceived time seems to be the cause of the weird slow motion feeling we get when slowing down after a long drive. It is probably related to the frequency with which we "sample" our surroundings. This would increase as we go faster and  decrease as we go slower, but do so gradually as the "sampling" becomes incorporated into our circadian rhythms.

We perceive time via our ability to perceive the world in frames, as if in a movie.

Champion sportspeople seem to have the ability to perceive time in slow motion.
.

[Bill S]

Actually that is EXACTLY for this thread.

There are some points I need to clarify, in my own mind….

This arose from attempts at clarification.

Do we know what the nature of time is?  Probably not.
Do we need to know what the nature of time is, in order to do physics or understand the Universe?  Apparently not.

Time figures prominently in St Augustine’s works, Newton’s laws of motion, relativity and quantum physics, but none of these requires a knowledge of the nature of time.  Even clockmakers do not need this knowledge.

Clocks can give us a glimpse of what we should be looking for.  As far as I am aware, all clocks involve some sort of movement. It may be the leisurely swinging of a large pendulum or the almost unthinkably rapid transition frequency of the caesium-133 atom, but all these movements, in common with every other movement in the Universe, involve change.

This is some progress; time, it seems, is inextricably linked to change, but can we go further?  It looks as though we can, but there is a fork in the path.

To Newton, it made sense to treat time as though it were a fundamental property of the Universe.  He treated space in the same way.  Both were fixed and immutable; they had to be in order to quantify motion.  It would be pointless to say that it takes “x” seconds to travel “y” distance if either “x” or “y" could, for no apparent reason, change its value.  This path leads to “real” time that is as “concrete” a feature of the Universe as space or mass. 

Einstein threw a spanner in the works when he brought to general notice that time passes at different rates depending on an observer’s relative motion, or the local strength of the gravitational field.  He produced some clever maths to show how this worked.  When he said: “Time is nothing but a stubbornly persistent illusion”, one might be forgiven for thinking that time was on its way out.  However, illusion or not, it continues to be stubbornly persistent.

Possibly one reason for the persistence was the fact that Minkowski created a four-dimensional manifold which he called “spacetime”.  Time became the fourth dimension.  It might seem as though we are moving back towards the Newtonian view of fundamental time, but we have to ask if spacetime is “concrete”.  Brian Greene (The Fabric of the Cosmos) says: “spacetime is a something”.  The next question must be: Is that “something” more than just a mathematical concept?  If it is just a mathematical concept, it is certainly a useful one, but so is the curvature of spacetime with respect to the force of gravity.

This second path leads, surely, to the view that change is the fundamental property of the Universe, and that time emerges from our need to understand the changing Universe around us.  Here we hit a stumbling block.  What do we mean by “time emerges”?  First there was no time, then time manifested?  If there were no time, nothing could happen, so time could not emerge.  What it must mean is that change was always a possibility, but could not be measured, or even recognised, without some measuring process.  This process is an illusion which our minds create in order to make sense of our Universe. 

[Frankwopsy]

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[Colin2B]

Hi all,

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@Frankwopsy
I don't understand why you have posted this in “Re: Split from "How fundamental is time?". What are you referring to?

Also, we do not allow spam so have removed your website reference. Further spam will mean a ban.

[mxplxxx (OP)]

This second path leads, surely, to the view that change is the fundamental property of the Universe, and that time emerges from our need to understand the changing Universe around us.  Here we hit a stumbling block.  What do we mean by “time emerges”?  First there was no time, then time manifested?  If there were no time, nothing could happen, so time could not emerge.

There is no time without distance. This was the case at the "time" of the big bang. As soon as our universe started expanding, so time started affecting it. The more our universe expands the slower time passes and correspondingly the less energy there is per cubic meter in the universe (via Eh/t). Sooner of later, the expansion of the universe will come to a halt as the amount of energy per square meter will not be enough to overcome gravity. It will then, likely, collapse to a singularity again and then go "bang" for a repeat of the cycle.

[mxplxxx (OP)]

There is no time without distance. This was the case at the "time" of the big bang.

Actually physics postulates that the big bang started from a singularity which probably contains a small "amount" of distance. According to quantum theory the singularity will have an Action of h (Planck's constant) and will "contain" energy of E=h/t where t = wavelength (of singularity) / SOL. If wavelength (a distance) = 0 then an infinite amount of energy is involved, which is impossible. But an extremely small amount of time will give rise to an extremely large amount of energy which makes sense.

Actually, distance is interesting. It is, seemingly, continuous. This gives it an infinite aspect. If the singularity  discussed above has even the tiniest amount of distance, a new universe can be created from it, ad infinitum. The new universe can be created in a top-down fashion much like a computer program creating a database. i.e Universe object created first, then galaxy cluster objects then galaxy objects and so on. Distance and therefore time (Distance /SOL) in this scenario is "perceived" by the "aware" entities in these universes as a percentage of the total universe, rather than absolute distances/times.  More about this later in New Theories.

Actually, when I say "tiniest" amount of distance, I am talking relatively. There only needs to be the existence of a single continuous entity for it to "contain" an infinite amount of "anything" that can be described as a concept, including time. What we experience as our reality is a digital universe which is one of the "things" contained in the continuous entity that we are part of, that approximates the continuous entity. Phew!:)

[mxplxxx (OP)]

This process is an illusion which our minds create in order to make sense of our Universe. 

And different types of minds create different types of illusions, but who knows whether their experience of time varies?

[mxplxxx (OP)]

The new universe can be created in a top-down fashion much like a computer program creating a database. i.e Universe object created first, then galaxy cluster objects then galaxy objects and so on.

Before each new object is created, the universe must be expanded so as to be able to fit the new object. Hence the expanding universe with, simultaneously, the dilution of the "amount" of time per unit area of the universe. In other words, the universe steadily loses power as it expands and at some point in time (about now!) has just the right amount of power to support life.

[mxplxxx (OP)]

Einstein threw a spanner in the works when he brought to general notice that time passes at different rates depending on an observer’s relative motion, or the local strength of the gravitational field.  He produced some clever maths to show how this worked.  When he said: “Time is nothing but a stubbornly persistent illusion”, one might be forgiven for thinking that time was on its way out.  However, illusion or not, it continues to be stubbornly persistent.

But his theories have never been proven (https://www.quora.com/Has-Einstein-s-theory-of-relativity-been-proven-1/answer/I-P-K-R-Hirwani), and after a century of trying. Given the theories are so weird, we could be forgiven for thinking that they never will be.

[Bill S]

My understanding is that, in science, theories are not proven correct. The best one can do is keep trying to prove them wrong. “After a century of trying”, success is singularly lacking, as far as SR and GR are concerned. Einstein made mistakes.  Hans Ohanian filled a book with them.  Don’t read it if you have a glowing opinion of Einstein as a person, which you want to preserve.   

[mxplxxx (OP)]

My understanding is that, in science, theories are not proven correct. The best one can do is keep trying to prove them wrong. “After a century of trying”, success is singularly lacking, as far as SR and GR are concerned. Einstein made mistakes.  Hans Ohanian filled a book with them.  Don’t read it if you have a glowing opinion of Einstein as a person, which you want to preserve.   

In an attempt to understand time, I bought a book "The Order of Time" by Carlo Rovelli. I had an isssue with the book and emailed him with:

"I am  reading your interesting new book “The Order of Time”. On page 12, you say “If things fall, it is due to this slowing down of time”, but you give no reasons why this might be so. Is this just an unsubstantiated statement? Is Relativity based on this unsubstantiated statement?"

I got the following reply:

"No, it is because according to classical mechanics things move following the path that extremes the traveling time between the initial and the final point. In flat spacetime, this path is a straight line.   When time is slowed down by a mass, this path happens to curve towards the mass, and a sort mathematical calculation shows that it is precisely the path followed by the falling bodies."

Mumbo, jumbo to me I am afraid. If a supposed expert cannot lucidly explain Einsteinian gravity, what hope is there for the theory.

[alancalverd]

Rovelli has just described the Principle of Least Action, but since you believe that Action is a mystery beyond the comprehnson of mere mortals you have to reject it as mumbo jumbo