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Posted: 21 June 2010 02:20 AM   [ Ignore ]   [ # 136 ]
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GdB - 20 June 2010 05:55 AM
StephenLawrence - 19 June 2010 01:57 PM

If broken cups started jumping off the floor and reforming on the table, wouldn’t it still seem that the cup was intitially in pieces on the floor and afterwards was complete on the table?

If…Yes, but it doesn’t. And it will not. How is this ‘if’ an argument?


the idea is that times arrow has something to do with enthropy. I think this if questions that.

How is this ‘key to us’? If I’ll ask you that we meet tomorrow at 13:30 Paddington station, do you have any relevant problem to understand this? Time is important to us, but we do not need an exact understanding about what time really is to work and live with it. Even in an existential important way we do not need to know more about the ‘real nature of time’. What additional understanding do you need when I say to you that one day in the future you will die?

GdB

You can argue I don’t need to know more, but there is more to know and it is very important stuff, if we are to understand what we are, how we persist through time and what time is.

Lets say I was born sixth august 1962 and will die 6th august 2042 (I’ll need to drink a little less wheat beer to make it)

So in about 32 years I will die. that time will get closer and closer because now is moving along. why does now move along? why does it appear to be 2010 to me? Is it? Or is this an illusion. If you say of course it is 2010, which knowing you, you will, then you should be able to see there is a lot of explaining to do. Is it objectively 2010? My life spans over 80 years in this example, why is it 2010 rather than 1974 or 2041 as far as I’m concerned. why is my now moving along?

That’s what you need to get to grips with to understand time and our concept of self.

If we don’t do this we are very much in the dark.

Stephen

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Posted: 21 June 2010 02:26 AM   [ Ignore ]   [ # 137 ]
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StephenLawrence - 21 June 2010 02:20 AM

You can argue I don’t need to know more, but there is more to know and it is very important stuff, if we are to understand what we are, how we persist through time and what time is.

But what are the consequences for our morality and other values? There is still a big “if” in your statement. I would say it is very interesting. But not all questions need an answer in any absolute sense in order to live a meaningful and just life.

GdB

[ Edited: 21 June 2010 02:30 AM by GdB ]
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Posted: 21 June 2010 02:34 AM   [ Ignore ]   [ # 138 ]
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GdB - 21 June 2010 02:26 AM
StephenLawrence - 21 June 2010 02:20 AM

You can argue I don’t need to know more, but there is more to know and it is very important stuff, if we are to understand what we are, how we persist through time and what time is.

But what are the consequences for our morality and other values? There is still a big “if” in your statement. I would say it is very interesting. But not all questions need an answer in any absolute sense in order to live a meaningful and just life.

GdB

Now we are moving to philosophy, so we’d need to continue on another thread. I think as far as responsibility goes, what me today had to do with what me yesterday did is pretty important. I’d plump for absolutely nothing!

But really this moving along now is just the most bamboozling thing isn’t it? We just wanna know stuff like this, don’t we?

And if we knew it might well have amazing consequences, we just can’t tell.

Stephen

[ Edited: 21 June 2010 02:40 AM by StephenLawrence ]
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Posted: 21 June 2010 02:42 AM   [ Ignore ]   [ # 139 ]
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GdB - 20 June 2010 01:50 PM

That does not enlighten very much…

The most fundamental level in physics is microphysics, in the quantum realm. The measurement problem, that by observing a quantum object it exists and if it is not observed, it is in a superposition of various states, raises the question, is the act of observation (the cause) of the quantum object coming into existence (the effect) or what exactly is happening? Another example is the emergence of virtual quantum particles from “quantum foam”. What is the cause of this phenomena? So, the notion of cause and effect is problematic at this level in physics.

OK, I forgot to add ‘without friction’. In 2D, they start parallel, and then they move without any force (inertia). So they move to each other without any additional force.

Since the ships have inertia, they must initially be subject to a force before they can move at all. This is also true of the apple or any object with mass. Where is that force in GR?

From the wiki on inertia

This would include an object that is not in motion (velocity = zero), which will remain at rest until some force causes it to move.

From this article in Discover magazine on Time may not exist

Efforts to understand time below the Planck scale have led to an exceedingly strange juncture in physics. The problem, in brief, is that time may not exist at the most fundamental level of physical reality. If so, then what is time? And why is it so obviously and tyrannically omnipresent in our own experience? “The meaning of time has become terribly problematic in contemporary physics,” says Simon Saunders, a philosopher of physics at the University of Oxford. “The situation is so uncomfortable that by far the best thing to do is declare oneself an agnostic.”

That’s charming, isn’t it?

grin

[ Edited: 21 June 2010 03:37 AM by kkwan ]
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Posted: 05 July 2010 12:55 AM   [ Ignore ]   [ # 140 ]
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kkwan - 21 June 2010 02:42 AM

Since the ships have inertia, they must initially be subject to a force before they can move at all. This is also true of the apple or any object with mass. Where is that force in GR?

OK. GR says that everything moves on the shortest possible way between 2 points in space/time. So (with a risk that I take the parallel too far…), imagine our globe as having a time coordinate (the meridians), and one space dimension (along the equator). The ships are not subject to any force. But as time progresses, the ships move in time, i.e. move to the north pole. Without any force, the ships are moving to each other: in the space dimension they come close and closer, without force. That is one of the essences of GR: that it explains gravity without the concept of force.

GdB

[ Edited: 05 July 2010 05:57 AM by GdB ]
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Posted: 05 July 2010 05:35 AM   [ Ignore ]   [ # 141 ]
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At the risk of hijacking a thread, I wanted to share a few thoughts I have had on time…

The simplest way to understand time, and the only one that makes sense in our current worldview, is to handle it as a dimension (just like the spatial ones). And to view that dimension as a mono directional track, or ‘arrow.’ This simple analogy grants us many insights, but also limitations.

It explains, for instance, the discrepencies on clocks in orbit, redshift, and why aliens have not landed. But trying to pigeon hole time as a single dimension travelling in a single direction may be limiting. There are two reasons I say this; first is that mathematicly all events can occur exactly as they do were time traveling in the opposite direction, and the second is a little more vague so I will attempt an analogy. A man on the surface of the planet can travel in a straight line, without deviating, and without crossing his own path arrive back where he started. This happens because he is travelling in a third dimension he is unaware of. But my ultimate speculation is what if there is another dimension to time itself? What if all matter can travel in a single direction through time and space (outward) without ever deviating and wind up back where it all started? ...Of course all attempts at visualizing a 5 or 6 dimensional universe has led only to headaches for me (damn this frail fleshy mind!)

It seems as though the greatest breakthroughs we have made so far is actually asserting things that seem so very different are actually the same: mass/energy, time/space… what if entropy/evolution is our next breakthrough? As long as we can only see time as an ‘arrow,’ we will find it very hard to draw parrallels between evolution (increasing complexity) and entropy (decreasing complexity).

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Posted: 06 July 2010 04:19 PM   [ Ignore ]   [ # 142 ]
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Stormy Fairweather - 05 July 2010 05:35 AM

The simplest way to understand time, and the only one that makes sense in our current worldview, is to handle it as a dimension (just like the spatial ones). And to view that dimension as a mono directional track, or ‘arrow.’ This simple analogy grants us many insights, but also limitations.

It explains, for instance, the discrepencies on clocks in orbit, redshift, and why aliens have not landed. But trying to pigeon hole time as a single dimension travelling in a single direction may be limiting. There are two reasons I say this; first is that mathematicly all events can occur exactly as they do were time traveling in the opposite direction…

Don’t forget that mathematics often gives us extraneous answers.

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Posted: 06 July 2010 07:59 PM   [ Ignore ]   [ # 143 ]
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Math is a methodology, if you are getting non relevent answers it is because you put in non relevent information.

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Posted: 06 July 2010 08:38 PM   [ Ignore ]   [ # 144 ]
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Stormy Fairweather - 06 July 2010 07:59 PM

Math is a methodology, if you are getting non relevent answers it is because you put in non relevent information.

Have you taken high school algebra? Any time you square both sides of an equation to eliminate a square root you have to check your answers to make sure the negative solution is valid.

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Posted: 07 July 2010 02:25 AM   [ Ignore ]   [ # 145 ]
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At the risk of offending…

Every time I see you make a post Darron, it seems to me that you miss the message for the medium. You fixate on a detail, or part of a statement, and then debate/discuss that rather than the actual idea presented. That is a fallacy, though one of the more subtle ones.

I feel no need to defend math as a tool for understanding reality. Math has proven its value time and time again, and just because the answers might cause headaches does not invalidate them, though the implications may invalidate worldviews. But as a final point, if my speculation on time having multiple dimensions is accurate, then the fact that events are identical regardless of the direction of times’ flow is hardly ‘extraneous.’

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Posted: 07 July 2010 05:25 AM   [ Ignore ]   [ # 146 ]
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No, I did not miss the message of time moving two directions, at least mathematically. In the real universe, however, no one has ever observed this. When reality disagrees with our theories, the theories need to change.

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Posted: 07 July 2010 05:43 AM   [ Ignore ]   [ # 147 ]
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DarronS - 07 July 2010 05:25 AM

No, I did not miss the message of time moving two directions, at least mathematically. In the real universe, however, no one has ever observed this. When reality disagrees with our theories, the theories need to change.

We haven’t observed time moving in any direction have we?

 

Stephen

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Posted: 07 July 2010 05:49 AM   [ Ignore ]   [ # 148 ]
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That is a tricky question, Stephen. As discussed earlier in this thread time is how we measure change, but the definition is circular. It comes down to accepting the reality that we need to make assumptions about certain things which can never be proven, then test our assumptions. Our assumptions about time have (No! No! Don’t say it!) withstood the test of time. (Aaaarrrrggghhhh!) Experiments and observations confirm entropy moves in one direction. Entropy is change, so time is really a measure of entropy. No one has ever observed entropy decreasing in a closed system.

Could it happen? Of course. We don’t know everything, but until our observations change the best theory we have to explain our observations is that time moves forward only.

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Posted: 07 July 2010 05:50 AM   [ Ignore ]   [ # 149 ]
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Stormy Fairweather - 05 July 2010 05:35 AM

At the risk of hijacking a thread, I wanted to share a few thoughts I have had on time…

A man on the surface of the planet can travel in a straight line, without deviating, and without crossing his own path arrive back where he started.

I have thought about your “ultimate speculation” but it just made my head hurt grin

I thought I’d offer my speculation.

Is what you’ve said here true? We can make sense of it but where is the bit of space you left? You’re not back in it are you?

My speculation is we don’t travel back to the same bit of space, anymore than we travel back to the same bit of time. Thinking we can in space and not in time is confusing us.

Stephen

[ Edited: 07 July 2010 06:05 AM by StephenLawrence ]
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Posted: 07 July 2010 06:12 AM   [ Ignore ]   [ # 150 ]
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DarronS - 07 July 2010 05:49 AM

That is a tricky question, Stephen. As discussed earlier in this thread time is how we measure change, but the definition is circular. It comes down to accepting the reality that we need to make assumptions about certain things which can never be proven, then test our assumptions. Our assumptions about time have (No! No! Don’t say it!) withstood the test of time. (Aaaarrrrggghhhh!)

grin

Experiments and observations confirm entropy moves in one direction. Entropy is change, so time is really a measure of entropy. No one has ever observed entropy decreasing in a closed system.

Could it happen? Of course. We don’t know everything, but until our observations change the best theory we have to explain our observations is that time moves forward only.

We have a sense of before and after. We can remember the past but not the future. In one sense Time’s arrow refers to this before and after. This arrow would be unaffected by entropy going into reverse. As I said to GdB If broken cups started jumping onto tables and landing in one piece, there would still be the same sense of before and after to these events. We can only go from before to after, not after to before.

Entropy does not seem to explain this aspect of times arrow.

Stephen

[ Edited: 07 July 2010 06:22 AM by StephenLawrence ]
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