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Author Topic:   What is Time and Space
Son Goku
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Posts: 1103
From: Ireland
Joined: 07-16-2005
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 Message 196 of 204 (348130) 09-11-2006 1:57 PM Reply to: Message 195 by GDR09-10-2006 6:54 PM

Re: Time
I assume you know what Energy is.

Now for work:
Work is basically Energy by distance, the amount of effort it takes to move across a distance.
Action is basically Work by time or "Energy by distance by time", the amount of effort it takes to move a distance x and through a period of time t.

One of the axioms of classical mechanics is that, for any system, the action takes the smallest possible value it can.
A little more formally the Principle of Least Action (for most systems) states that the difference between Kinetic and Potential Energy is kept to a minimum.
This is called the principle of least action, made famous by the physicist Hamilton.
(Who used the walk the canal behind the house that I grew up in.)

Edited by Son Goku, : Spelling

Edited by Son Goku, : Expansion.

 This message is a reply to: Message 195 by GDR, posted 09-10-2006 6:54 PM GDR has responded

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GDR
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Joined: 05-22-2005
Member Rating: 1.9

 Message 197 of 204 (348132) 09-11-2006 2:16 PM Reply to: Message 196 by Son Goku09-11-2006 1:57 PM

Re: Time
That is really helpful. Thanks. Now I have to try and envision that path that cavediver was talking about.

By the way here is an item on Barbour from the edge.

http://www.edge.org/3rd_culture/barbour/barbour_index.html

Everybody is entitled to my opinion. :)
 This message is a reply to: Message 196 by Son Goku, posted 09-11-2006 1:57 PM Son Goku has not yet responded

nipok
Inactive Member

 Message 198 of 204 (348291) 09-12-2006 2:22 AM Reply to: Message 186 by GDR09-08-2006 3:17 PM

Re: Time
 That is my basic problem. I don't understand what it means to have multiple or infinite universes. It may be that there is no way to understand it outside of mathematics.

That is because everything that the currently accepted paradigm focuses on is the time and space that we can detect and our interpretations of their coexistence. Time and space are a fabric, an infinitely large and infinitely small fabric that matter and life revolve upon and reevolve upon and they are very intricately intertwined with mathematical equations. The way I like to think of it is to use a lowercase u as in universe to represent all that we can detect both inwards and outwards and an uppercase U as in Universe to represent the infinite fabric of space-time that our tiny little universe exists within. Our “Point” in space-time that we call our universe or what I would classify as our Outer Significant Relative Pocket of Space Time is one of an infinite number of such pockets of space-time each with their own unique re-EVOLutionary path though our shared fabric.

 This message is a reply to: Message 186 by GDR, posted 09-08-2006 3:17 PM GDR has not yet responded

GDR
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Joined: 05-22-2005
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 Message 199 of 204 (354052) 10-04-2006 12:03 AM Reply to: Message 187 by cavediver09-08-2006 3:23 PM

Re: Time
GDR writes:

When you say in the last sentence "our universe" are you speaking about a universe that is the one that all of us experience?

 cavediver writes:Could be, or perhaps individualistic... the model's not sufficiently well defined on that point! Take you pick...

I’m still trying to put all of this together conceptually and particularly the idea of an individualistic universe.

-Penrose proposes that consciousness is basic to everything.
-Barbour believes that every moment is an eternal universe.
-Others talk about an infinite number of universes
-SR tells us that space/time is absolute and that we all move through time at our own individual rate.
-QM has shown us that nothing is as it appears and that what seems to be reality is in fact only our perception of it, and that in order for particles, (which are only bits of energy or information), to take on their characteristics they require an observer.

If all of these things are correct, (I know that the first three are still pretty esoteric and pretty speculative), then it seems to me that some things follow.

If the movement through time is an individual thing for each of us(SR), and if a universe is a specific moment in time (Barbour) then every individual exists in their own universe that is dependent on their own consciousness, (Penrose & QM) which would require an infinite number of universes.

Does this make any sense at all?

Edited by GDR, : No reason given.

Everybody is entitled to my opinion. :)
 This message is a reply to: Message 187 by cavediver, posted 09-08-2006 3:23 PM cavediver has not yet responded

GDR
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 Message 200 of 204 (385628) 02-16-2007 1:25 PM

Does time even exist
Julian Barbour as I understand it contends that time as such doesn't even exist but is only the way that we perceive change. Here is a link to a site that includes a discussion with Barbour and a review of his book.

Julian Barbour

Amongst the many things that I don't understand in all of this is how his picture of how time represents change is consistent with GR which shows that time, (as represented by change) is different for each one of us.

Everybody is entitled to my opinion. :)
john6zx
Member (Idle past 2597 days)
Posts: 66
Joined: 01-27-2007

 Message 201 of 204 (465437) 05-07-2008 12:10 AM Reply to: Message 4 by NosyNed07-29-2005 9:08 AM

Re: Uniform Time
Quote from NosyNed post>
 Starting on page 233, Greene explains the uniformity of time.quote:--------------------------------------------------------------------------------Using a slight variation on the ballon model, we can now understand more precisely how symmetry in space, even though space is expanding, yields a notion of time that applies uniformly across the cosmos.

This is a definition of notion.

NOTION –noun
1. a general understanding; vague or imperfect conception or idea of something: a notion of how something should be done.
2. an opinion, view, or belief: That's his notion, not mine.
3. conception or idea: his notion of democracy.
4. a fanciful or foolish idea; whim: She had a notion to swim in the winter.

So do you think that MR. Green is saying that time is basically a concept?

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cavediver
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Posts: 4129
From: UK
Joined: 06-16-2005

 Message 202 of 204 (465458) 05-07-2008 4:43 AM Reply to: Message 201 by john6zx05-07-2008 12:10 AM

Re: Uniform Time
 So do you think that MR. Green is saying that time is basically a concept?

I guess that must depend on what you mean by 'concept'. Off the top of my head, 'time' refers colloquially to at least three different concepts in General Relativity, and mixing these up is at the heart of most of confusion in this topic. Time is a dimension, it is a coordinate, it is a path through space-time, it is a rate (of affine parameterisation) along that path - ah, that's four...

 This message is a reply to: Message 201 by john6zx, posted 05-07-2008 12:10 AM john6zx has responded

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john6zx
Member (Idle past 2597 days)
Posts: 66
Joined: 01-27-2007

 Message 203 of 204 (466080) 05-13-2008 1:26 AM Reply to: Message 202 by cavediver05-07-2008 4:43 AM

Re: Uniform Time
Originally posted by john6zx
So do you think that MR. Green is saying that time is basically a concept?

 I guess that must depend on what you mean by 'concept'. Off the top of my head, 'time' refers colloquially to at least three different concepts in General Relativity, and mixing these up is at the heart of most of confusion in this topic. Time is a dimension, it is a coordinate, it is a path through space-time, it is a rate (of affine parameterisation) along that path - ah, that's four...

The definition of concept that I am using.

Concept:
1. a general notion or idea; conception.
2. an idea of something formed by mentally combining all its characteristics or particulars; a construct.
3. a directly conceived or intuited object of thought.

Alright, lets take this one step at a time.

First off I have to mention that I am not looking for answers that are right according to how others define time. I am discussing this topic with you, so when I ask a question I would like to hear what YOU think. I am not testing/challenging you with any of my questions. I just want to discuss the topic of time.

With that said, do you think that time is some sort of physical form of energy?

You mentioned General Relativity and time being a dimensions, a coordinate,and a path through space-time.

All that can be cleared up once it has been established if time is a physical thing or not.

It would also help you to find out if dimensions are physical things. Is there any scientific reference or definition that states dimensions are physical things? Or are they just concepts of measurement?

A coordinate. Is that a physical thing? Or just a concept used to define a position of a real or imagined thing?

As for the whole space-time subject, that term uses the idea of time so it would be best to find out what time is before using space-time to descibe time.

Again, I do not want you to think that this is some type of contest to see who can be "more" right than the other. I am not interested in that. I would just like to have a discussion on the nature of time.

Here is what I think time is:

Time is actually a consideration based on our perception of the movement of objects. There is a distance, there is a velocity of the objects travel, and that movement of that object or particle in relationship to its starting point and in relationship to its ending point is what gives us the idea of time. Time is a manifestation which has no existence beyond the idea of time brought about by the motion of objects, where an object may be either energy or matter. Time is not a thing that flows. Time does not move or cause things to move. It is this perception of motion which gives us the idea of time.

Thank You.

john6zx

 This message is a reply to: Message 202 by cavediver, posted 05-07-2008 4:43 AM cavediver has not yet responded

GDR
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 Message 204 of 204 (642907) 12-02-2011 2:56 PM

A Course in Time
I have been enjoying the thread on "Time and Beginning to Exist" and I remembered a number of years ago starting this thread and how helpful so many were to me in getting my head around time and space. There are some excellent teachers around here and so I thought it might be interesting to bring this forward for those who are interested.

(Just ignore my own rather inane postings. I mean well.)

Everybody is entitled to my opinion. :)

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