Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Nimrod on 06/06/2009 20:08:50
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To me it seems impossible to have change without the concept of time and vice versa. If you had a volume of space in which nothing changed, would time still flow? If it did, it seems time would have no meaning. If time was still flowing at the normal rate, could we tell in which direction it was flowing (i.e. forward or backward)? I certainly cannot imagine change happening without time, could time flow without change? Can anyone offer a thought experiment that might shed some light on this question?
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You can't have one without the other. Hmm that seems to need a musical accompaniment.
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Change does seem to depend upon time, at least from our point of view.
Perhaps the best way to illustrate it is that with time, you can have a single item, the state of which can change over time. Without time though, to accommodate the two states (before and after) you'd need two instances of the item, one for each state, and unless they're both to exist as a single super-state, they must exist in different places.
Thinking of time as a 'flow' doesn't really help. Rather than something that 'flows' past us, it is better to think of time as something we pass through, the difference being that it is us that moves, not time. If we then go back to looking at the two different states, we can look at them as either happening one after the other, or as existing simultaneously, albeit at different locations in time.
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"Is tme and change the same phenomenon?"
Change is evidence for the passage of what we humans understand as time. Whether they are the same phenomenon or not is quite arguable.
In a universe void of matter or energy, could one argue that time still procedes at a uniform pace? Could we even have a universe without matter or energy? These are questions which, I dare-say, we will never have answers for.
Time is a construct we humans use to explain the passage of events, without the observation of these events, how would we measure the march of time? And when we consider that according to the theory of Relativity, the passage of time is not uniform between observers moving at different velocities one to the other. According to this theory, time is not invariant and does not procede at a uniform pace. Just how accurate this view of things is could be questioned. Nevertheless, my own take on time is this; Time is only a principle for understanding the process of one event followed by another, whether time is an independent feature of existence or not, we may never really know ....................Ethos
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You can't have one without the other. Hmm that seems to need a musical accompaniment.
Love and marriage, love and marriage, go together like a horse and carriage..................Change and time, change and time, go together like rhythm and ryhme.
Sorry,...........I just couldn't help myself. [:X] [:X] [:X] [:X] [;D]
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If you draw a graph on a piece of paper showing a mathematical function like
y = x2 then it will show how y changes for different values of x; you get a parabola. Because of the way we 'experience' it, it is not difficult to appreciate that relationship for what it is. You can see what value of y will be produced for any value of x, you care to choose. (Or vice versa). You can see the whole picture.
If you were only allowed to view the graph through a vertical slot which was moving horizontally across the page, you would only see one value of y at a time. You'd have to use your memory to recall the past values you'd seen and, unless you'd sussed out it was a parabola, each new value would be a wonderful surprise.
To my mind, it could be a bit like that with things that vary with time. Our experience only allows us to appreciate things 'as they develop in time' but it's possible to remember the bits whic our moving time slot has passed over and it's often possible to predict what we will observe in the future, when we have identified a pattern.
If we could step outside of our particular set of observed dimensions, we could see events from beginning to end and, in any order - just like when we see the xy graph we drew - only with t on the horizontal axis.
I am not even sure that entropy and thermodynamics actually make things significantly different; there are many mathematical functions which get more and more complicated as x increases - or decreases.
Maybe the 'direction' of time's arrow is just defined as the direction which takes us towards more and more complication. I have no idea how this should relate to our consciousness of time progressing but there are many studies, in their early stages, of the mind and how it relates to our structure. Just imagine if the way our consciousness developed were merely based on appreciating things in the direction of increasing entropy; we could have made our own arrow for time as our brains developed.
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If you draw a graph on a piece of paper showing a mathematical function like
y = x2 then it will show how y changes for different values of x; you get a parabola. Because of the way we 'experience' it, it is not difficult to appreciate that relationship for what it is. You can see what value of y will be produced for any value of x, you care to choose. (Or vice versa). You can see the whole picture.
If you were only allowed to view the graph through a vertical slot which was moving horizontally across the page, you would only see one value of y at a time. You'd have to use your memory to recall the past values you'd seen and, unless you'd sussed out it was a parabola, each new value would be a wonderful surprise.
To my mind, it could be a bit like that with things that vary with time. Our experience only allows us to appreciate things 'as they develop in time' but it's possible to remember the bits whic our moving time slot has passed over and it's often possible to predict what we will observe in the future, when we have identified a pattern.
Thanks! That's a really fantastic way of thinking about it/explaining it!
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Only a personal view, you understand. It is fairly self-consistent, though.
Glad you like it.
PS I did shoot myself in the foot, rather in the final sentence which takes for granted a direction of time's arrow. But, maybe not.
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If you draw a graph on a piece of paper showing a mathematical function like
y = x2 then it will show how y changes for different values of x; you get a parabola. Because of the way we 'experience' it, it is not difficult to appreciate that relationship for what it is. You can see what value of y will be produced for any value of x, you care to choose. (Or vice versa). You can see the whole picture.
If you were only allowed to view the graph through a vertical slot which was moving horizontally across the page, you would only see one value of y at a time. You'd have to use your memory to recall the past values you'd seen and, unless you'd sussed out it was a parabola, each new value would be a wonderful surprise.
To my mind, it could be a bit like that with things that vary with time. Our experience only allows us to appreciate things 'as they develop in time' but it's possible to remember the bits whic our moving time slot has passed over and it's often possible to predict what we will observe in the future, when we have identified a pattern.
If we could step outside of our particular set of observed dimensions, we could see events from beginning to end and, in any order - just like when we see the xy graph we drew - only with t on the horizontal axis.
I like this illustration too, a lot [;D]
Just one question: how wide is the slot? [;)]
The direction of movement of time is a very interesting issue and offers some tantalising possibilities. For example, cannot a repulsive force can be viewed as an attractive force, but with a reversed time vector? [:-\]
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How long is 'now'? That's the width of the slot.
It should be no more of a problem to discuss instants of time than intantaneous position of a moving object.
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How long is 'now'? That's the width of the slot.
It should be no more of a problem to discuss instants of time than intantaneous position of a moving object.
I think I agree with all of that. Seems straightforward enough in theory; it's just getting your head around the answers, so that they actually mean something in practice, that's tricky.