atrahasis

Has anybody seen/heard about Julian barbour new book "The end time"?
Julian asks if a tree fell in the forest with no one around to hear it. would time pass since nothing changed? "If nothing happened, if nothing changed,time would stop,"he writes. "For time is nothing but change. It is change that we perceive as occuring all around us,not time. In fact time does not exist.

If time does not really exist, what are the implication on physics.

With my own understanding Time does not exist.
Unless otherwise convinced, I'm keeping an open mind here.

But before that, let me first say why i think time does NOT EXIST.

A1)
Physicists struggling to unify quantum mechanics and Einstein's general theory of relativity have found hints that the universe is Timeless.

support for A1)
30 years ago, Bryce Dewitt and John Wheeler combined quantum mechanics and Einstein's thoery of general relativity to produce an equation that describes the whole universe. Put into the equation, a configuration of the universe, and out comes a probability for that configuration. There is no mention of time. Admittedly, the Wheeler-Dewitt equation is controversial and fraught with mathematical difficulties, but if quantum cosmology is anything like it-if it is about probabilities-the timeless picture is plausible.

I believe that this idea should be taken seriously. Paradoxically we might be able to explain the mysterious "arrow of Time"-the difference between past and future-by abandoning time.
But to understand how, we need to change radically our ideas of how the universe works.

Kharakov

Time is the comparison of rates of change.

-k

atrahasis

Premise A).
Time is the comparison
If Time is the comparison what is the comparison itself? Time? No! Premise A) Fails!

Premise B).
of rates of change
This depends on premise A) which failed, then it is also fails.

The conclusion is False.
You can do better than that!

Ierrellus

Black Moses,

Time as quantification of motion involved in change is a useful concept. Duration, however, appears to exist regardless of how it is defined (clock time, mood time syncopated time, etc.) Is mechanical time being confused with experential time here?

"The only thing permanent is change"--Heraclitus

Ierrellus
PAX

Daniel_AnglumTM

In my mind the question of Weather time exists is one that cannot have a singular answer....

scumble

I'm aware of the line of thought in Physics that is skeptical of time as an actual entity, if you like. Although the Newtonian concept of an absolute time is blown away by Relativity, there is no consideration of what time actually is. Without events, even relativity doesn't really mean anything.
I suppose classical time, like classical mechanics, could be just an effect of the many quantum events that occur beneath the surface.
Our entire perception of time is based on events, and is not constant. Time can appear to go by slowly or quickly depending on that perception.

Bill

Anybody who begins with the old tree falling in the forest business is departing from a platform of postmodernist philosophy.

Time is one of those ancient concepts that has acquired many layers of complex meanings over the thousands of years of human civilization. But the question you raise is stated as a universal, so the answer should not depend upon human experience, or even the existence of humans to experience anything.

Barbour seems to take the existentialist view of things not existing without personal perception. That view is inherently contradictory to the idea of universals, which is the real basis of the question you've stated.

Based upon my rejection of the idea of an actual singularity at T=0 time of the Big Bang, the consequences of that rejection are that space and time must have existed at T=0 regardless of anything else. That all of space and time were wrapped up in an extremely small ball is far more acceptable in my view than the idea that they were compressed so that all sizes were equal to zero. And if they were small, but finitely so, as I believe, then they clearly existed at T=0 and we have no reason to believe that they were in any way "created" at T=0. Instead, the clear implication is that both space and time are part of some larger continuum. The nature of that larger continuum is almost totally unknown. However, we do infer its existence, and we have numerous speculations about its nature.

You mention the probability of some particular world existing, which is an implication of the so-called "many worlds" view of quantum mechanics. That view is an almost religious view of physics because it is so counter-intuitive. While one version of me sits here completing this thought, some other version of me gets up and goes to the bathroom, with each eventuality having some probability of being true. But no universal way of ascertaining which probability is "real" and which is "imaginary." That is just totally counter-intuitive because everything that we are as humans comes from our perception of a straight line existence from the past through the present and on into the future.

Anyway, in a few years (or perhaps decades) we will have our "Theory of Everything" and then we will have the actual equations that make sense of how relativity, quantum mechanics, time, space, energy, and matter all relate to one another. Until then, we have only speculations. And while speculations are fun sometimes, they can be dangerous if you are too quick to assert their absolute truth when there is no proof. At this juncture in human experience, we cannot say whether time and/or space are permanent fixtures of the metrical frame of the universe or if they are in some way specially created as part of something like the "Big Bang." We just have to be patient and wait for science to produce the answer.

== Bill

atrahasis

Originally posted by Ierrellus:
Black Moses,

Time as quantification of motion involved in change is a useful concept.This only true in classical physics, But in QM it is not.
The fact is that motion can still be measured without involving Time.

Duration, however, appears to exist regardless of how it is defined (clock time, mood time syncopated time, etc.)
Lets substitute the term "Duration" with the term "change" and any term "time" with the "change" also.Is your argument still sound? Yes i'm sure it still is.

Is mechanical time being confused with experential time here?
Any of this does not make the argument less sound any will do. As long it is still time!

"The only thing permanent is change"
This premise opposes this premise Time as quantification of motion involved in change is a useful conceptYou mention.

It is a:
Fallacious form argument Denying the Antacedent)
1. If A then B,
2. Not A
Not B

atrahasis

Bill said,
"We just have to be patient and wait for science to produce the answer"

Wait for science? We are the scientists. You put it as if science is a domain out there which does all the thinking and brings us all answers to our questions except a few.

Lastly Bill, Why is that T=0 why not T= -10000000.

[ July 27, 2002: Message edited by: Black Moses ]</p>

Ted Hoffman

Time is a human concept, just like civilization and morality.

Time is a tool for measuring change.

When there is no one to count the time, then time ceases to exist.

In a world where there is no change (ie no entropy), time stands still.

Does a dozen exist?