Cause and defect

Misfit
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Mike Hewson
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Cause and defect


This is actually old ground, the earlier ( errr... later ? ) QM theorists did bite hard on this stuff.
A positron can be viewed as an electron going backwards in time for instance. One theoretician ( I forget who ) even had only one electron ( ever! ) in the universe which kept getting re-used for all interactions/worldines. This explained why all electrons seem to be the same! One variant proposed the wave function travelling backward in time to the point of an event thus 'causing' it. Feynman and contemporaries, in the 1950's, led up to quantum electrodynamics by analysing this sort of stuff.
Up to a point there's just alot of dicking around with language, but non-locality and entanglement can and have been demonstrated.
One curious aspect is that for a photon ( or anything else at light speed ) the 'proper time' is zero - meaning that time does not pass, clocks don't tick, and photons don't 'age' in that reference frame. So in that frame there is no time dimension. If in our view ( sub-light speed ) a photon was emitted at such and such a point in spacetime, travelled, and then was absorbed at some other point in spacetime - then for the photon these phases are all simultaneous ( or time is meaningless ) and only the spatial aspects remain to describe it's path.
Never-the-less there is a clear asymmetry to be explained whatever the version - eggs break into pieces and never assemble from them - in the world of our experience. So whatever 'predictive' theory is around must encompass that.
Cheers, Mike.

( edit ) If you have read Terry Pratchett's 'Discworld' series, which I heartily recommend, the trolls feel they are travelling from the future to the past. This arises from the simple observation that they can see the past 'in front' of them but not the future 'behind' them. :-)

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

Chipper Q
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RE: One curious aspect is

Quote:
One curious aspect is that for a photon ( or anything else at light speed ) the 'proper time' is zero - meaning that time does not pass, clocks don't tick, and photons don't 'age' in that reference frame. So in that frame there is no time dimension. If in our view ( sub-light speed ) a photon was emitted at such and such a point in spacetime, travelled, and then was absorbed at some other point in spacetime - then for the photon these phases are all simultaneous ( or time is meaningless ) and only the spatial aspects remain to describe it's path.


Wow, I really like how you phrased this. I've read in the literature questions to the effect, "How does the photon know which way to go (e.g., which slit to pass through)?" and from what you've stated, the answer would be, "It knows because it's already there!"

Yet, I've read (Feynman) that each photon has its own 'stopwatch' of sorts, related obviously to frequency, and so how is this to be reconciled with the photon's sense of no time during transit?

MarkF
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ChipperQ: Proper time is the

ChipperQ:
Proper time is the interval measured by clock co-moving along the world line of the particle in question. For a particle moving at the speed of light such a clock would not tick. It is just as accurate to say the proper distance is zero.
The progress of the Feynman ‘stopwatch(s)’ are defined relative to the background metric. What Feynman is describing is a complex numbers which can be defined as a magnitude and a phase angle. The magnitude is any number between 0 and infinity the phase varies between 0 and 2 pi.

Chipper Q
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Mark wrote: Mark

Mark wrote:

Mark wrote:
Proper time is the interval measured by clock co-moving along the world line of the particle in question. For a particle moving at the speed of light such a clock would not tick. It is just as accurate to say the proper distance is zero.

Thanks, Mark. So then proper time, for anything moving as fast as light, is experienced as a kind of singularity?

Mike wrote:

Mike wrote:
One theoretician ( I forget who ) even had only one electron ( ever! ) in the universe which kept getting re-used for all interactions/worldines. This explained why all electrons seem to be the same! One variant proposed the wave function travelling backward in time to the point of an event thus 'causing' it.

Pretty sure it was Feynman... found this post here from a quick google, has some interesting remarks, and clicking on the Richard P. Feynman link in the first post also pulls up an interesting page about him (lots of his often-quoted remarks)...

MarkF
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ChipperQ: RE: Thanks,

ChipperQ:

Quote:
Thanks, Mark. So then proper time, for anything moving as fast as light, is experienced as a kind of singularity?


The usual convention is 1) dt^2 c^2-dx^2>0 for anything moving at less than the speed of light 2) dt^2 c^2-dx^2=0 for something traveling at the speed of light 3) then by implication dt^2 c^2-dx^2>0 should be faster than the speed of light. But case 3 is really a spatial displacement instead of a temporal one.

You can always find a Lorentz transformation that will set dx=0 for case 1. Similarly you can always find a Lorentz transformation that will set dt=0 for case 3. Neither dx nor dt can be set to 0 by a Lorentz transformation in case 2,

Chipper Q
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From light's frame of

From light's frame of reference, there is zero distance and zero time between each and every point in the universe? I read an interesting article recently saying that it can be demonstrated that light travels backwards faster than it does going forwards, when going from one medium to another. Curiouser and curiouser... :) Of course it's nothing new to say, "we're all connected"...

Also found this page while attempting to understand the implications of case #2, in Mark's most recent post: The Relativity of Light
Please correct the following statement if it needs it:
Invariance doesn't arise from the just the principle that the laws of physics are everywhere the same, but more specifically it arises from correct mathematical analysis of these laws, as sets of mathematical constructs, when they are in motion relative to one another (i.e., when the inertia of any object is measured from differing inertial frames of reference).

Odysseus
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RE: Sure it is—if

Message 40157 in response to message 40154

Quote:


Sure it is—if you click the reply link associated with an existing message. See Mike Hewson’s posting near the top of this thread, in particular the link to Misfit’s message in the ‘header’. (This message of mine should likewise show a link to yours.) However, the “reply to this thread� link at the bottom of the page (which is what you apparently used) produces a blank message field.

Chipper Q
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Hi, Odysseus The effect I

Hi, Odysseus

The effect I was referring to, when you click , forms the quote tags like this: Sure is it...
And when the tags are formed like that, the interpretor formats the quoted material as usual, but additionally adds the name of the source in bold type, preceding the area bounding the quoted material, so that the final output appears like this:

Odysseus wrote:

Quote:
Sure it is...
Odysseus
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Chipper Q wrote:The effect I

Message 40159 in response to message 40158

Chipper Q wrote:
The effect I was referring to, when you click , forms the quote tags like this: Sure is it...


Ah, sorry: I misunderstood the issue. I haven't noticed anyone using such a feature on any of the BOINC boards I’ve visited. Since the BBCode syntax uses square brackets instead of angled, I would guess your example is from somewhere that accepts HTML.

I tried giving the “quote� tag a value above, but it clearly doesn’t do anything—although it doesn’t prevent the tag from being recognized.

Chipper Q
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RE: ...I would guess your

Quote:
...I would guess your example is from somewhere that accepts HTML.


Just using the to illustrate (should've mentioned that); the other forum uses square brackets too, calls the protocol 'BBCode', and employs the exact same set of tags (e.g., to emphasize text, provide links, images, code, etc.). Thanks for trying to be helpful. Come to think of it, used to be that HTML tags worked in this forum...

@Misfit: Sorry that this is totally OT, because it is an awesome topic, and thanks for bringing it up.

Questions for anyone:

There are theories on extra dimensions (beyond 3-spatial + 1-temporal), but are there any on 3-spatial + 1-inflated singularity? Regarding one single electron, how about one lone, albeit inflated, photon as well?

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