Imaginary Time

wolsty

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I'm reading Stephen Hawking again The Universe in a Nutshell) He's just introduced me to imaginary time. He says you can show it on a graph at right angles to ordinary time and that the standing still of real time and imaginary time means that spacetime has a temperature.

Oooooooh. My head hurts.

:confused
 

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The methods of measuring capacitance and inductance of electronic circuitry are with the use of imaginary 'i' or 'j' values, which are portrayed graphically at right angles to the real voltage and current.

Using the imaginary values gives mathematicians an insight into the ways material moves in the universe, from the electrons in radio tuning circuits, mechanical suspension systems (compression and damping), to the interaction of one galaxy to another.

As for equating time to temperature, Im not so sure, but then again I havent spent as much time sat in front of a PC, figuring out just how far these formulae can be applied. In my advanced school days though, we were introduced to the dimensioning method, allowing a check on an equation, to verify that even if the final answer was wrong, measurements within the equation balanced on both sides.

Pressure, volume and temperature are related in the Law governing gases in confined spaces, and in a different law the rate of cooling of an object is directly related to the mass of a material as well as the temperature difference, and so its not so great a leap to conclude time and temperature are related in some way, beyond the normal Laws of standard Physics
 

wolsty

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You sound just like my friend the aerospace engineer, CH. I was telling him aboout my difficulties and he said more or less the same as you. What you both forget is that I don't have anything beyond O level maths and physics and I've only just got used to the concept of imaginary numbers.
 

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What difficulties ?

A head hurting is a sign that you are using it, even if its because youve lost the hammer

Imaginary numbers are a way of conveniently entering a parameter into a system, to make the answer right, but the logic behind the use of them is only valid if you agree and accept to all the terms of the argument.

One reason why I no longer argue with the other half - I simply offer agreement to her answer - especially if its tangential to the original question (usually hers), and leave it at that -otherwise my head starts hurting
 

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I'm off on holiday tomorrow. Three weeks caravanning in France should give me enough time to ponder all this.

When I agree with my wife, she accuses me of sarcasm. If I don't agree with her I'm accused of being difficult.

I think women are programmed by their DNA never to ask a direct question and always go off at a tangent when they get an aswer they don't like.

Did I say that I like living dangerously?
 

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Only if she can see what you are typing
 

wolsty

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I re-read Hawking's 'The Universe in a Nutshell' whilst on holiday and am now fairly clear on imaginary time. CH's explanation helped.

I must say, however, that this latest book does nothing to improve Hawking's reputation. Apart from the fact that it's an American publication with all the usual, irritating, transatlantic illiteracies such as 'color' and 'fit' instead of 'fitted', the diagrams are very poor. In an attempt to increase the book's appeal to the non-scientist, the illustrations are of an ersatz 19th Century Science Fiction style, thus making them difficult to understand. This is not helped by the fact that some text figures are not properly labelled or don't have a scale for the graphs. The text is, however, pretty lucid.

In the introduction, Hawking says that he intended to produce a sequel to A Brief History of Time which is more readable and easier for the layman to comprehend. If that be so, his publisher has let him down. ABHOT is, I think, a much more informative book and an enjoyable read.

By contrast, I'm just coming to the end of John Gribbin's 'In Pursuit of the Big Bang'. It's better written, contains more information, uses mathematical expressions where they are helpful, has excellent text figures and, since it's a Penguin paperback, costs less that Hawking's book.

It's sad to see a prominent mathematician's work being dumbed down and I can't avoid the conclusion that Hawking's uniqueness has turned him into a 'brand' which is being shamelessly exploited.

:-band
 

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It would be rather difficuklt for Mr Hawking to storm into the publishers and shout his argument across, however as long as the pennies are transferring into the bank account, it would seem preferable to stick with the present sequence of events. Attempting to please everyone at the expense of unpopularity with those pushing the book on your behalf sounds like a recipe for disaster.

John Gribbin's 'In Pursuit of the Big Bang' - is it original enough to be
worth the read ?

Im finding one of Iain Banks books (Excession) rather difficult to concentrate on with the present workload. Give me a Larry Niven short novel any day. A lunchtime treat rather than a monthly chore.
 

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The fact that he can't storm into the publisher's and complain is what leads me to think his name is being exploited - that and the fact that his disability makes him memorable. And I'm not sure if it's trying to please everybody - more a case of a sloppily presented book relying on a big name to sell. But, as you say, why should he worry if the money keeps coming in?

John Gribbin's always worth a read, but it depends on your level of knowledge as to how much original or new material you'll find. For a layman such as me, he's first rate. Cogent, succinct and very readable. Not afraid of venturing an opinion, but very much a review of the state of knowledge rather than a contribution to it. ISOTBB is one of his best and compares well with 'In Search of Schrodinger's Cat'.

I've also just read Bill Bryson's 'A Short History of Nearly Everything' and enjoyed it very much, despite one or two obvious errors and some fuzzy descriptions. If you like his travel book style, you'll enjoy the anecdotes even if you don't learn a lot. A recommended read for someone who thinks Science is for nerds.
 

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As we have strayed onto Bill Bryson can I recommend his book "The Mother Tongue: English and How It Got That Way" which givws a really good dip into the waters that are the English language.

If you find that interesting can I then recommend "A History of the English Language" by Albert C Baugh and Thomas Cable. You'll probably have to get this one out of the library though as it's rather expensive.

WRT Hawking and Gribbin my opinion is that Hawking knows his stuff (obviously!) and tries just a bit too hard to put it across to the general public. I read his BHOT and found it interesting (although a bit out of date in places) and curiously lacking in depth in others.

John Gribbin is someone whose wprk is always readable. I first saw his name when I used to get New Scientist 20 years ago. I would like to read some of his books now - so a trip to the library is in order Ithink.

PaulR
 

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I agree that Hawking's style of popular prose is a little forced - not his natural way of writing. Mostly it's understandable. But what I object to is publishers cashing in on his name.

Gribbin is very good. I first encounterd him in New Scientist and liked what I read. 'In Search of Schroedinger's Cat' is excellent. The sequel, Schroedinger's Kittens is less compelling. 'In Search of the Big Bang' is well worth reading, particularly in the latest, paperback edition.

Another outstanding book is 'The Elegant Universe' by Brian Greene. Good on Quantum Mechanics, but then it explores Strings and Membranes in a readable and understandable fashion.

Bryson's work is always funny, but I suspect that he sometimes sacrifices accuracy to make his anecdotes more amusing. Certainly his 'Mother Tongue' is worth reading if only to remind us that Americans speak a form of English closer to that of Shakespeare than we do in the UK.
 

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Did Bill and Francis pronounce z as 'zee' ?
 

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At this time of morning it has to be a large expresso
 

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If you hit metal with EM radiation most of the radiation is reflected back. Some of the radiation is absorbed by the metal this is know as the skin effect. To calculate the amount of EM absorbed, one way is to imagine that the absorbed travels through the metal and out the other side. To calculate this imaginary numbers are used I and J. Since most theories including parrallel universes and time flow all came obout from the concept of EM flow and how and what it does certain things. I wonder if Steven Hawkings is taking Time as a flow and equating it to other physics theories. After all the goal is unifying all theories into a super theroy. Just a thought.
 

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funkymothership said:
If you hit metal with EM radiation most of the radiation is reflected back. Some of the radiation is absorbed by the metal this is know as the skin effect. To calculate the amount of EM absorbed, one way is to imagine that the absorbed travels through the metal and out the other side. To calculate this imaginary numbers are used I and J. Since most theories including parrallel universes and time flow all came obout from the concept of EM flow and how and what it does certain things. I wonder if Steven Hawkings is taking Time as a flow and equating it to other physics theories. After all the goal is unifying all theories into a super theroy. Just a thought.


All the stuff in this thread is way over my head. This is the reason I skipped this subject many years ago and went straight for science fiction! At least there I understand what is going on :D

And if someone here wants to read some good stuff try to find books by Corwinder Smith. A bit unknown but worth a read.

*funkymothership: Are you talking Mr. Clinton here?! Just got one of his in my car player O-Ha
 

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getting back to "imaginary" time .....

There's nothing imaginary about "i", it crops up quite naturally in equations, and is no more mysterious than the integers, 1,2,3 ... etc. Reason is, all numbers are equally mysterious! You can point to 5 things, but try defining "fiveness" without circular reference back to other numbers.

"i" was added to special relativity by Minkowski, giving "4 dimensional space-time", rather than just equations, but it's a "calculating fiction", it does not have particular physical significance.

In other calculations, "i" is used as a phase-shifter, as mentioned above, it "shifts" sine waves. That's so in electrical "i notation" (phasors), also quantum mechanics for the "matter-waves".
 

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having just read original post again, I believe Hawking is referring to a "topology shift", at the start of universe (and possibly also at the end, if there's ever a "big crunch"), where the 4-d axis rotates, so that the time "i" axis "points" where the space ones later will. No, I don't understand it either. But it's discussed in "pop science" book The Nature Of Space And Time, by Hawking and Penrose, which keeps maths to minimum and concentrates on descriptions, worth looking at if you're interested.

(Googling "hawking penrose" will get a selection of short articles and book reviews).
 

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Damn, the 4-axis has just tilted again, must remember to set my watch to "North", and compass to GMT.
 

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spiney said:
having just read original post again, I believe Hawking is referring to a "topology shift", at the start of universe (and possibly also at the end, if there's ever a "big crunch"), where the 4-d axis rotates, so that the time "i" axis "points" where the space ones later will. No, I don't understand it either. But it's discussed in "pop science" book The Nature Of Space And Time, by Hawking and Penrose, which keeps maths to minimum and concentrates on descriptions, worth looking at if you're interested.
.

I think Mr Hawkings started looking over my shoulder, damn cheat.
(he didnt see the full formula though, so he's made a mistake in the above, as there is no beginning or end of the universe, just a reversal of time on a regular basis)
 
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