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Space-Time


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Posted on Jun 29, 2012 4:28:52 AM PDT
Last edited by the author on Jun 29, 2012 6:38:19 AM PDT
Sure, I understand what you mean *how people may or may not -think- about time is not relevant to how the concept is -used- in physics. * and I agree the 'concept' is extremely useful, if not completely indispensable, in our everyday lives + physics.

I just think that around 'time' there is an extremely unscientific vague grey area about what actually exists and does not exist. And it is this that I am addressing. (If you look at many book titles on time they imply directly that they are apparently about a real thing, which may be 'warped', and -really- considered as a 4th dimension, etc).

E.g. when someone as distinguished in the field of cosmology as Hawking says "rapid space-travel, or travel back in time, can't be ruled out, according to our present understanding", ( http://www.hawking.org.uk/space-and-time-warps.html ).

Then I am 'confused'. Is the cosmological expert, Professor Hawking saying it is completely understood that time is nothing more than a useful mental concept... but it's 'fun' to 'pretend' it is real, and could be travelled through? Or is he saying that the current expert understanding is that time is a real thing?

It seems a problem to me that anyone else in such a scientific field is happy to say 'it doesn't matter if this fundamental 'time' thing is real or just an idea. But let's not bother to clarify it, let's just carry on talking about it ambiguously, and try to work out any confusion that follows, as if all before it has been checked'.

I'm obviously paraphrasing, but in the 'jigsaw puzzle of physics', I`m looking at the piece marked 'time' and saying I think I can show that's wrong. And just as in a real puzzle, if a single piece is wrong but assumed to be right, or not to matter, then there will always be problems around that piece which will hinder the puzzle as a whole being solved. (added)- And lead to endless, circular discussions. Inherently inconclusive because they build on poorly defined, and scientifically unchecked hypothesis (e.g. that terms like 'the past' relate to some real thing, and not just a useful 'idea').

RE *with an implicit understanding of before/after assumed*, try pushing a mug etc, from left to right with your finger. Is your finger really 'in the past', doing something before now, so that after-wards the mugs position is changed 'in the future'? Or is everything always just happening now.

My guess is that immediately on reading the above, you may want to say something about 'semantics'. If so, it is, imo, absolutely critical, -not- to just assume a semantic problem has been spotted, therefore the matter is closed. But instead to be absolutely clear whether the semantic confusions around 'time'...

A -Wrongly- use language to make it look like time does not exist. or,
B- Wrongly- use language to make it look like time does exist.

I'm just suggesting I can fully show B is the case, and that if it is the case that time does not really exist, it is quite amazing, and very useful to grasp as many answers and simplifications of various relativity issues etc follow.
mm

In reply to an earlier post on Jun 29, 2012 4:39:48 AM PDT
Last edited by the author on Jun 29, 2012 4:43:24 AM PDT
Jack Shandy says:
I go for option C:

C- Existence/nonexistence is not decided by language, but by physics.

And the physics points to the possibility to define a parameter to quantify change. And when we have defined such a parameter, we can give it a name, like 'time'.

Posted on Jun 29, 2012 5:21:11 AM PDT
Last edited by the author on Jun 29, 2012 5:28:53 AM PDT
=) I agree, by physics.

You can't just conjurer up the existence of some 'thing' by making up a different name for one thing, and then start using this name as if you have shown some thing 'else' also exists.

So, i agree with you.

-we just, i.e. only, observe 'change',

-we choose a name for units of the one and only thing 'change' that we observe,

-and (with respect to him) professor Hawking is completely wrong when he says "rapid space-travel, or travel back in 'time', can't be ruled out, according to our present understanding"
because he has misunderstood that all we see is change.

And he has wrongly assumed that because we defined a 'parameter' and named units for change, this means something 'extra' to just change exists.
And jumped to the incorrect conclusion and we might be able to travel 'through' these 'units' that we made up.

It just seems fascinating to me that so many experts don't spot where an invisible intangible thing really doesn't exist, but is just a another 'word' for simple change.
mm

In reply to an earlier post on Jun 29, 2012 5:37:41 AM PDT
Nova137 says:
Mr.MM,

I read the link.

Time = consciousness.

Here is an interesting article by John L. Bell (http://publish.uwo.ca/~jbell/) who takes a stab at explicating/understanding the Godel Universe where time travel is possible:

http://publish.uwo.ca/~jbell/Time.pdf

In reply to an earlier post on Jun 29, 2012 6:15:08 AM PDT
Last edited by the author on Jun 29, 2012 6:53:17 AM PDT
thanks Nova, will do...

thanks, that's actually a very good example of what I mean in this post...

http://www.amazon.com/forum/science/ref=cm_cd_et_md_pl?_encoding=UTF8&cdForum=FxZ58KVEERYS5E&cdMsgNo=476&cdPage=20&cdSort=oldest&cdThread=Tx1V353DWZ3ISSV&cdMsgID=MxMP2TGKXYUFVG#MxMP2TGKXYUFVG

where I say,
**
in the 'jigsaw puzzle of physics', I`m looking at the piece marked 'time' and saying I think I can show that's wrong. And just as in a real puzzle, if a single piece is wrong but assumed to be right, or not to matter, then there will always be problems around that piece which will hinder the puzzle as a whole being solved.

(added)- And lead to endless, circular discussions. Inherently inconclusive because they build on poorly defined, and scientifically unchecked hypothesis (e.g. that terms like 'the past' relate to some real thing, and not just a useful 'idea').
**

In the document u point to - Bell says, "Kurt Gödel constructed the first mathematical models of the universe in which travel into the past is, in theory at least, possible."

Which is fine, but if we are to expend a great deal of thought on working out if we could 'travel into the past' - surely we should be absolutely clear that this expression 'the' 'past' relates to a -real- thing.

And is -not- just a misunderstanding based on thinking that the contents of our minds prove more than 'that things can just move and change'.

And, that this 'time' thing is a -real- phenomena in the universe, and not as I believe, and as Jack Shandy explained, just "a parameter to quantify 'change' ".

I've asked a number of people on this and other forums to post a link to a page that outlines why we should accept 'the past' is a thing that exists, (or even a scientific experiment proving that it does, as is required for every other point taken in a scientific discussion as a fact) and so far, out of the billions of pages out there, no one has mentioned such a page :^/
mm

In reply to an earlier post on Jun 29, 2012 7:28:00 AM PDT
major mistake

models are NOT reality
reality is NOT a model

people who use models and do simulation too long lose touch with what is real and start thinking their models are the true reality

In reply to an earlier post on Jun 29, 2012 7:29:45 AM PDT
physics decides nothing

reality is
indepent of physics

physics ASSumes that it can approximate reality close enough with a model to understand it

physics is way wrong

In reply to an earlier post on Jun 29, 2012 7:59:57 AM PDT
I thought the problem with QCD was just computational intractability, rather than any known defect in the theory per se.

I know that some people believe that any physical theory is of necessity only an approximation to reality, but I don't understand how you know that if you have a theory for which no proven disagreement between calculated versus observed measurements is known.

Agree that if you stop at a given order of the perturbation expansion in QED by definition you'll get a small difference from any given higher order of the perturbation expansion, but I'm not sure that one can rule out that QED is in fact a perfect representation of the physical reality of electrons, photons, and their interactions below the energy cutoff.

It would be nice to think that there is a theory of physical reality which is a perfect representation of it, meaning our quest for a better understanding of physical reality has a final triumph.

In reply to an earlier post on Jun 29, 2012 8:00:32 AM PDT
There's a difference between "perfect" and "perfectly known".

In reply to an earlier post on Jun 29, 2012 8:04:09 AM PDT
I would agree that one can't exclude the possibility that a theory for which there is no known discrepancy between calculated and observed values (except for the error of measurement) is in fact a perfect representation of physical reality, i.e., a kind of completed quest for the Holy Grail, if you will.

In reply to an earlier post on Jun 29, 2012 8:05:01 AM PDT
I'm having trouble understanding how something that can be measured with attosecond precision can be considered "poorly defined".

In reply to an earlier post on Jun 29, 2012 8:05:55 AM PDT
Are you sure the "vague grey area" is not just in your own understanding? I don't mean to be insulting when I say this, but you are IMO projecting your own confusion onto science.

In reply to an earlier post on Jun 29, 2012 8:07:23 AM PDT
What if every single observation you can make about reality to the utmost precision of your measuring equipment is exactly matched by a theory's calculated values? How can you exclude that the theory is not in fact a perfect representation of physical reality?

In reply to an earlier post on Jun 29, 2012 8:07:48 AM PDT
You're making ridiculously sweeping and uninformed statements.

In reply to an earlier post on Jun 29, 2012 8:57:51 AM PDT
Last edited by the author on Jun 29, 2012 9:29:02 AM PDT
By attosecond,

do you mean 'second' as another word for change, as in 0.0042 degrees of the Earth spinning on it's axis might also be called 'one second'. (If so I agree things move, and we can measure movement, rotation, or vibration, very accurately)

Or do you mean 'second' as relating to word 'time', implying ...

- a 'thing' that in some way passes from an intangible place or thing called the future which does 'not exist' 'yet'...
-constantly 'through' all that we see around us...
-'into' an intangible place or thing called the past, which does 'not exist', but 'did',
-and which if Gödel, Hawking, etc are correct could be theoretically travelled into (despite no longer existing)?

If so could you please,

-define what you mean by 'time', extra to just change in the present (to use a redundant term if there is just change),
-define what and where 'the future' is, and what reason you have to think it exists,
-define what and where 'the past' is, and why you think, that extra to what we directly observe, 'it' exists (+ constantly ceases to exist as it is created).
-define how and why a thing called time also passes through all we observe, and why you think things don't just rotate, or move from A to B if they have energy or momentum.

In reply to an earlier post on Jun 29, 2012 9:16:05 AM PDT
Last edited by the author on Jun 29, 2012 9:17:43 AM PDT
maybe you need attofemtoyottosec resolution
maybe it is truly stochastic and not exact

you dont know for sure

and that little difference could change all the models
and explain for the discrepancies

In reply to an earlier post on Jun 29, 2012 9:16:49 AM PDT
because every model we have has problems somewhere
even though very very good in a specific limited domain

In reply to an earlier post on Jun 29, 2012 9:17:26 AM PDT
no

i am speaking the accurate truth as a mathematician and a logical thinker

you are confusing your models with what is actually real

In reply to an earlier post on Jun 29, 2012 9:58:03 AM PDT
Last edited by the author on Jun 29, 2012 10:14:05 AM PDT
andthehorse...,

As an experimental matter, we probably don't. But on the theoretical side, the spin statistic is set by definition, straight from the mathematical assumptions. The spin is quantized in units of h(bar). Now, one might suggest that h is only approximately known, in terms of Joule*seconds, and that pi (part of the expansion of h(bar)) is only known out to 5 trillion decimal places or so, but these issues go away in the system of "natural units".

By way of analogy, it is one thing to say that we don't know what the decimal representation of pi is, but it is quite another to say that we don't know its value in *any* representation. In fact, there are more than a hundred known representations that are much more well behaved than the decimal expansion. For instance, we know that (pi^2)/6 = 1/1^2 + 1/2^2 + 1/3^2 + ... ** This formula, and many others, are well understood, totally predictable, mathematically proven, and don't suffer from any sort of 'randomness' in the way that the decimal expansion does.

[**Note: The ellipsis in this formula can be expanded without the aid of a calculator, simply by following the rule. The right side may be written more compactly as "The SUM of (1/n^2), for n=1 to infinity"]

In reply to an earlier post on Jun 29, 2012 10:02:12 AM PDT
Last edited by the author on Jun 29, 2012 10:05:30 AM PDT
Jack,

I am not of a mind to suggest that there *is* any such thing as 'actual reality', and I wouldn't say I was seeking it. But I would point out that if there were one, then Newton missed the boat.

In reply to an earlier post on Jun 29, 2012 10:05:12 AM PDT
Last edited by the author on Jun 29, 2012 10:13:40 AM PDT
af,

True enough... But how does this apply? If the theory cannot generate a perfectly accurate answer, how can it be known to be perfect?

Posted on Jun 29, 2012 10:35:24 AM PDT
[Deleted by Amazon on Jun 29, 2012 5:56:08 PM PDT]

In reply to an earlier post on Jun 29, 2012 10:46:58 AM PDT
Last edited by the author on Jun 29, 2012 10:51:29 AM PDT
Change and time are equivalent. You can't set up a physical theory incorporating change without somehow dragging time into it.

I've already defined what I mean by all those things. Here goes again. Last time!

Time is what is measured by clocks.

The future is the set of physical states that the current physical state will change into with the subsequent ticks of the clock.

The past is the set of physical states that changed into the current physical state, when the clock read earlier times.

The past no longer "is" anywhere, because those physical states changed into other ones.

The future does not yet exist, because the current physical state hasn't changed into the future ones yet.

Things don't "just rotate" or "just move" without somehow time being involved. I.e., you can't formulate a physical description/theory of motion or rotation without somehow dragging in time.

In reply to an earlier post on Jun 29, 2012 10:47:46 AM PDT
What discrepancies are you referring to?

In reply to an earlier post on Jun 29, 2012 10:48:49 AM PDT
Why couldn't QED be a perfect representation of the physical reality of electrons and photons below the cutoff energy? As far as I know no discrepancy has been reported between calculated and observed phenomena in this domain.
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