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Old Jun 15th 2018, 05:45 AM   #1
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Causality

I have just been reading an article in New Scientist
<Beyond Quantum Physics>
Which states:
Take causality, the cherished notion that cause always precedes effect. You may think this principle applies at all times and places throughout the universe. Instead, general relativity grants every observer their own notion of present and future, so it allows different people to disagree about the causal ordering of certain events.
I thought that while two observers might differ on the timing, and even the order of events,
the causality of one event with respect to another remained.
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Old Jun 15th 2018, 06:55 AM   #2
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Originally Posted by Woody View Post
I have just been reading an article in New Scientist
<Beyond Quantum Physics>
Which states:


I thought that while two observers might differ on the timing, and even the order of events,
the causality of one event with respect to another remained.
I couldn't access the whole article so I may be missing something but yes, causality is a requirement on any theory. Simultaneity is hosed but causality must be maintained, even in QM.

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Old Jun 15th 2018, 07:09 AM   #3
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This is all quiet mind boggling ....and like time travel raises logical paradoxes which seem impossible to resolve...

Jung was the first person to explore this. He noticed events in his life that could not be explained by causality , and he invented a new word Synchronicity ...

He defined it as ..... "an acausal connecting principle"

He didn't get very far in explaining it , but it revolves around the mind ....

Let me give an example of what he noticed .... an artist is painting a picture of a tabby tom cat,hours of focused concentration ... he takes a break , and relaxes in his garden ... up walks a tabby tom cat , he's never seen one in his neighborhood before ....

If such a thing happened only once it could be put down to coincidence , but Jung noticed many similar such occurrences in his life .... normally after intense periods of concentration on a particular theme ... he covers them in his autobiography ... After writing about the fish archetype he went for a walk and had 4 separate instances where fish popped up ...

The mind and focus are the key to making this happen ... magic ....you get what you concentrate on
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Old Jun 15th 2018, 08:49 AM   #4
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Originally Posted by Woody View Post
I have just been reading an article in New Scientist
<Beyond Quantum Physics>
Which states:


I thought that while two observers might differ on the timing, and even the order of events,
the causality of one event with respect to another remained.
You are 100% correct. Shame on them. It just goes to show you that smart people can say some dumb things at times.

Its only for events which have a spacelike spacetime separation does that hold true and that requires FTL communication.
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Old Jun 15th 2018, 10:30 AM   #5
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The Magic of Coincidence

The human memory is (of necessity) selective.
It is simply physically impossible to store all the events that occur in our lives,
So we remember the details of unusual events, but just the basics of the ordinary events.
Thus Jung will have noticed the few times when coincidences occurred,
but not the vast majority of events when nothing particular happened.

If one were to perform a proper statistical analysis of events where coincidences occur against events when they don't,
(even taking into consideration the intense concentration requirement)
one would find that the coincidences are well within the bounds of normal random happenstance.
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Old Jun 15th 2018, 02:32 PM   #6
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Thought Experiment

Tom and Richard are performing the standard entanglement "Spooky action at a distance" experiment.

Tom measures the spin of his particle and then Richard measures the spin of the entangled partner particle.
And sure enough Richard finds it has the appropriate spin to match what Tom observed.

Now we introduce Harry who is travelling at relativistic speed relative to Tom and Richard.
To him the order of the measuring events appears reversed,
Richard measures the spin first and then Tom finds that his particle matches.

This looks a bit like a reversal of cause and effect.

I am guessing though that the actual cause is the original entanglement event,
so both the observations are effects, and neither is a cause.

(Note; I couldn't use Richards nickname, the swear filter kicked in!)
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Old Jun 18th 2018, 04:36 AM   #7
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Tom and Richard carefully cut a coin down through the middle, such that the coin is now in two slices. One slice is heads, the other is tails. They close their eyes and I give one slice to Tom and the other slice to Richard. They each put their slice in their pocket, and at the appointed time they look and see whether they've got heads or tails.

Tom measures the heads and tails of his "particle" and then Richard measures the heads and tails of "the entangled partner particle". And sure enough Richard finds it has the appropriate heads/tails to match what Tom observed.

Now we introduce Harry who is travelling at relativistic speed relative to Tom and Richard. To him the order of the measuring events appears reversed. But it doesn't matter a damn.

New Scientist have a habit of peddling myth and mystery. It sells magazines.
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Old Jun 19th 2018, 05:52 AM   #8
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Originally Posted by Woody View Post
I am guessing though that the actual cause is the original entanglement event,
so both the observations are effects, and neither is a cause.
This!

Furthermore, entanglement problems are best solved by treating the two particles as a combined system with a single compound wave-function. In other words, treating the two particles as separate entities can lead to problems.
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Old Jun 19th 2018, 08:14 AM   #9
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Exploring where SR and QM disagree

Does the wave function allow for the relativistic observer?
i.e. can you put in alternative "time views" and it will still give the appropriate response?
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Old Jun 19th 2018, 08:29 AM   #10
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Originally Posted by Woody View Post
Does the wave function allow for the relativistic observer?
i.e. can you put in alternative "time views" and it will still give the appropriate response?
I have absolutely no idea because I don't know GR or QFT.
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