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Quantum causal relations: A causes B causes A
EurekAlert ^ | 10/2/12

Posted on 10/03/2012 4:33:24 PM PDT by LibWhacker

One of the most deeply rooted concepts in science and in our everyday life is causality; the idea that events in the present are caused by events in the past and, in turn, act as causes for what happens in the future. If an event A is a cause of an effect B, then B cannot be a cause of A. Now theoretical physicists from the University of Vienna and the Université Libre de Bruxelles have shown that in quantum mechanics it is possible to conceive situations in which a single event can be both, a cause and an effect of another one. The findings will be published this week in "Nature Communications".

Although it is still not known if such situations can be actually found in nature, the sheer possibility that they could exist may have far-reaching implications for the foundations of quantum mechanics, quantum gravity and quantum computing.

Causal relations: who influences whom

In everyday life and in classical physics, events are ordered in time: a cause can only influence an effect in its future not in its past. As a simple example, imagine a person, Alice, walking into a room and finding there a piece of paper. After reading what is written on the paper Alice erases the message and leaves her own message on the piece of paper. Another person, Bob, walks into the same room at some other time and does the same: he reads, erases and re-writes some message on the paper. If Bob enters the room after Alice, he will be able to read what she wrote; however Alice will not have a chance to know Bob's message. In this case, Alice's writing is the "cause" and what Bob reads the "effect". Each time the two repeat the procedure, only one will be able to read what the other wrote. Even if they don't have watches and don't know who enters the room first, they can deduce it by what they write and read on the paper. For example, Alice might write "Alice was here today", such that if Bob reads the message, he will know that he came to the room after her.

Quantum violation of causal order

As long as only the laws of classical physics are allowed, the order of events is fixed: either Bob or Alice is first to enter the room and leave a message for the other person. When quantum mechanics enters into play, however, the picture may change drastically. According to quantum mechanics, objects can lose their well-defined classical properties, such as e.g. a particle that can be at two different locations at the same time. In quantum physics this is called a "superposition". Now an international team of physicists led by Caslav Brukner from the University of Vienna have shown that even the causal order of events could be in such a superposition. If - in our example - Alice and Bob have a quantum system instead of an ordinary piece of paper to write their messages on, they can end up in a situation where each of them can read a part of the message written by the other. Effectively, one has a superposition of two situations: "Alice enters the room first and leaves a message before Bob" and "Bob enters the room first and leaves a message before Alice".

"Such a superposition, however, has not been considered in the standard formulation of quantum mechanics since the theory always assumes a definite causal order between events", says Ognyan Oreshkov from the Université Libre de Bruxelles (formerly University of Vienna). "But if we believe that quantum mechanics governs all phenomena, it is natural to expect that the order of events could also be indefinite, similarly to the location of a particle or its velocity", adds Fabio Costa from the University of Vienna.

The work provides an important step towards understanding that definite causal order might not be a mandatory property of nature. "The real challenge is finding out where in nature we should look for superpositions of causal orders", explains Caslav Brukner from the Quantum Optics, Quantum Nanophysics, Quantum Information group of the University of Vienna.


TOPICS: Science
KEYWORDS: causal; mechanics; quantum; relations; stringtheory
Not surprising to me. When I was a graduate student, I proved the temporal order of events was relative; i.e., whether event A precedes event B or B precedes A in time depends on the frame of reference of the observer. It was not a difficult proof. It's bothered me ever since because I concluded there is no such thing as cause. These authors say A can cause B AND B cause A. Either way, THE UNIVERSE IS INSANE! Or at least not based on logic and reason, which should bother us.
1 posted on 10/03/2012 4:33:28 PM PDT by LibWhacker
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To: LibWhacker

Unintented consequences are a fact of life.


2 posted on 10/03/2012 4:38:20 PM PDT by OldNavyVet
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To: LibWhacker
Firesign Theatre postulated in 1970:

“How can you be in 2 places at once when not anywhere at all?”

3 posted on 10/03/2012 4:38:44 PM PDT by AU72
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To: LibWhacker

How many frames of reference were you using? An outcome is still a singular event; the WTC is still gone, for example.


4 posted on 10/03/2012 4:41:29 PM PDT by Olog-hai
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To: LibWhacker
and the cat can be dead and alive at the same time... feh
5 posted on 10/03/2012 4:41:55 PM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: LibWhacker

If a video game programmer can code superposition into a game what would it look like? And of course our Creator can easily “code” superposition into our existence. (If you haven’t guessed already.. I know nothing about physics and very little about science in general.)


6 posted on 10/03/2012 4:45:06 PM PDT by WilliamofCarmichael (If modern America's Man on Horseback is out there, Get on the damn horse already!)
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To: LibWhacker

“But if we believe that quantum mechanics governs all phenomena...”

The key phrase. Quantum mechanics is an attempt to explain the behavior of subatomic particles and the forces that act upon them. If the theory works, it’s provisionally true. But this doesn’t mean we understand quantum behavior as it really is, just that we have an explanation of the quantum behavior that we have observed in experiments, which is an infinitesimally small proportion of all quantum behavior.


7 posted on 10/03/2012 4:45:12 PM PDT by oblomov
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To: LibWhacker

So it’s “Bob & Carol & Ted & Alice” or “Alice & Carol & Ted & Bob” depending on your “perspective”...


8 posted on 10/03/2012 4:45:37 PM PDT by mikrofon (Quantum Strangeness)
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To: Chode

Nah; that was Schrödinger’s brain cells.


9 posted on 10/03/2012 4:45:46 PM PDT by Olog-hai
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To: AU72

That’s easy when you work for the Department of Redundancy Department.


10 posted on 10/03/2012 4:47:23 PM PDT by Fresh Wind ('People have got to know whether or not their president is a crook.' Richard M. Nixon)
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To: WilliamofCarmichael

One is used to moving a video game character through space; now imagine that the character can move just as easily through time. Time is just another “direction” in which the character can move. So, from the character’s perspective, what is a cause, and what is an effect? If the character moves backward through time, the “effects” come before the “causes”. Now consider the subjective philosophical perspective of the game character...it would likely see a cause-effect relationship as being a duality, not a fixed, one-way relationship.


11 posted on 10/03/2012 4:53:24 PM PDT by oblomov
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To: Chode
I've been a physics fan for decades. Recently started reading again, just to see what's new, etc. Best book so far, out of the half dozen or so, is "Hidden in Plain Sight"

Hidden in Plain Sight Kindle Edition is 99 cents. The author is Andrew Thomas.

It helps, I think, if you've been exposed to quantum and relativity for awhile, and are either in awe or puzzled that the two regimes don't reconcile.

The other stuff I've been reading is heavy on string theory, which is sort of interesting and aims to put some more meat on what Mr. Thomas is getting at; and books about "dark matter" and "dark energy." Very strange physical world we live in, in many many ways.

12 posted on 10/03/2012 4:53:32 PM PDT by Cboldt
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To: LibWhacker

This reminds me of Borges’ masterful “Tloen, Uqbar, Orbis Tertius”:

http://www.coldbacon.com/writing/borges-tlon.html


13 posted on 10/03/2012 4:55:30 PM PDT by oblomov
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To: LibWhacker

So should I get a Obama phone or not?


14 posted on 10/03/2012 4:56:25 PM PDT by Lurkina.n.Learnin (Ignorance is bliss- I'm stoked)
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To: Olog-hai
pretty much...
15 posted on 10/03/2012 4:56:54 PM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: Cboldt

You seem to be reading material similar to what my older brother reads. He’s a virtual wealth of conversation when it comes to the deeper things of science and discussing them in layman’s terms.


16 posted on 10/03/2012 5:01:04 PM PDT by Fester Chugabrew (ABO to the core.)
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To: Cboldt
i've taken physics and read some quantum and string, but in the case of the cat there is or there isn't, not maybe... and the viewing of it makes no difference in the outcome at all that i can see, but then again i'm no physicist

and if things are in parallel universes, they aren't the same thing anyway

17 posted on 10/03/2012 5:04:51 PM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: Cboldt
Very strange physical world we live in, in many many ways.

Strange? As opposed to what, familiar? Physical? As opposed to what, mental? Relax, everything will be all right.

18 posted on 10/03/2012 5:08:32 PM PDT by Misterioso (Trying to explain music is like trying to dance architecture. -- Thelonious Monk)
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To: Cboldt
for 99c i'll pick one up with my next amazon order, thx
19 posted on 10/03/2012 5:09:28 PM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: Chode

How would you know?


20 posted on 10/03/2012 5:10:48 PM PDT by muawiyah
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To: Olog-hai

I used two. I showed the proof to a fellow grad student in math whom I respected. He said I must’ve made a mistake somewhere but couldn’t find it.


21 posted on 10/03/2012 5:13:44 PM PDT by LibWhacker
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To: Lurkina.n.Learnin

if you are on the foo stam you can already get obama phow


22 posted on 10/03/2012 5:15:00 PM PDT by Mr. K ("The only thing the World would hate more than the USA in charge is the USA NOT in charge")
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To: LibWhacker
it is possible to conceive situations in which a single event can be both, a cause and an effect of another one.

Any married guy could have told you that.

23 posted on 10/03/2012 5:18:10 PM PDT by Raycpa
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To: Lurkina.n.Learnin

It could make you rich. Or getting rich could make you buy one. Your choice.


24 posted on 10/03/2012 5:18:38 PM PDT by LibWhacker
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To: muawiyah
know what?
25 posted on 10/03/2012 5:19:00 PM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: oblomov
Thank you very much.

Physically would that be similar to recursion? Here a video character's actions could be influenced by his actions in each successive execution; but unlike "Ground Hogs Day" the video character could change the future? Eventually it does reach the desired end.

Thanks again.

26 posted on 10/03/2012 5:19:37 PM PDT by WilliamofCarmichael (If modern America's Man on Horseback is out there, Get on the damn horse already!)
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To: oblomov

That was a really great story!


27 posted on 10/03/2012 5:19:41 PM PDT by dinodino
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To: LibWhacker

I’m more confused now than I never was.


28 posted on 10/03/2012 5:22:16 PM PDT by Lurkina.n.Learnin (Ignorance is bliss- I'm stoked)
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To: Fester Chugabrew
-- You seem to be reading material similar to what my older brother reads. --

I wonder what the chances of that are.

29 posted on 10/03/2012 5:24:56 PM PDT by Cboldt
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To: Misterioso
-- Strange? As opposed to what, familiar? Physical? As opposed to what, mental? Relax, everything will be all right. --

"strange" as in doesn't follow intuition or common sense. Like, if your mother took a fast ride, she could come back and be younger than you are. One of my favorite remarks about physicists is that the closer they look, the more the stuff they are looking at disappears. Or, that what we think of as "solid" stuff is about 99.999999999999999% empty. (I guessed at the number of trailing nines there, but it's in the right neighborhood).

Agreed, thing will turn out fine. I read physics just because I find it interesting. I like music too.

30 posted on 10/03/2012 5:29:18 PM PDT by Cboldt
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To: Cboldt
Years ago ~ decades really ~ I worked for a half dozen statisticians who'd developed the RPW system for the Post Office Department ~ they later on worked on the Cost-Revenue Ascertainment system (a manifestation of the same objective).

These guys were a lot of fun. Most of them had served in WWII or the Korean War and every day was a breath of fresh air for them ~ even the crotchity ones.

So they had a feel ~ a real personal feel for probability.

Their hobbies were either dabbling in quantum physics, or figuring out what the structure of the elements was all about ~ plus visiting the Wailing Wall in Jerusalem as soon as that could be done. WWII had done things to their life's links that were simply incredible.

So, smart guys, right attitude, and well experienced in everything. Each one of them had his own interpretation for the Schroedinger Cat theorm. In fact, that little tale fell right in the middle of a sampling algorithm dilemma they'd come up with ~ which is very simple. When you have an ongoing continual process and you need to reach in and take a snapshot of just a second of time and something comes up that prevents you from doing so, what is the correct prophylaxis to take another sample at another time that will PROBABLY (Within some degree of certainty) replace the lost data?

Remembering that each little 1 second snapshot is going to represent hours of work and thousands of pieces of mail down the road as the typical second is structured for total agency operating costs, can you just wait 5 and try it again? Or is it more complex ~

These people consciously killed Schroedinger's cat every day ~ usually several times ~ because there's the answer to the question of when can you repeat your action and get the same result?

As I recall it if you kill the cat you can never repeat the action, so you gotta' leave the cat alone!

Decades later more advanced string theory theoreticians are getting more deeply into this problem ~ so I follow that stuff just in case one of them comes up with a better solution than just out and out killing the cat ~ the only action that allows you to stick a (new) kitty back in the box and strive for a different, but otherwise identical, result.

Then there's a whole school of thought with thousands of members who dispute the relevance of that cat to anything.

31 posted on 10/03/2012 5:30:45 PM PDT by muawiyah
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To: Cboldt; LibWhacker
"Strange" "Insane"

It will be the ultimate cruelty if we are never given a glimpse of the mystery.


32 posted on 10/03/2012 5:31:39 PM PDT by I see my hands (It's time to.. KICK OUT THE JAMS, MOTHER FREEPERS!)
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To: Chode
-- for 99c i'll pick one up with my next amazon order, thx --

He's with you on that Schroedinger's cat thing. Your opening the box isn't relevant to the outcome. He makes real good sense of the question of "what constitutes observation?"

33 posted on 10/03/2012 5:31:57 PM PDT by Cboldt
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To: LibWhacker

34 posted on 10/03/2012 5:56:49 PM PDT by martin_fierro (< |:)~)
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To: LibWhacker

Quantam crap is total horse manure.


35 posted on 10/03/2012 6:03:12 PM PDT by SolidRedState (I used to think bizarro world was a fiction.)
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To: Chode
Depressed cats cause radioactive decay. Shove one into a Schrödinger box and if the cat is depressed the radioactive sample will decay thus killing the cat. A happy cat will prevent that decay. Thus if we get enough happy cats together we can stop a nuclear bomb from going off.
36 posted on 10/03/2012 6:13:15 PM PDT by KarlInOhio ("Government is the only thing that we all belong to"=implicit repeal of the 13th amendment for all.)
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To: KarlInOhio
no way do i believe there are THAT many happy cats in the world... 8^)
37 posted on 10/03/2012 6:25:38 PM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: LibWhacker
Many atheists are atheists because they think science explains everything and that we will eventually be able to explain everything.

Quantum mechanics throws a monkey wrench into that idea.

I am positive a conscious observer of some kind was required to bring the universe into existence. Nothing occurs in the quantum universe without a conscious observer. Calling that observer "God" would not be outrageous.

38 posted on 10/03/2012 6:29:36 PM PDT by E. Pluribus Unum (Government is the religion of the psychopath.)
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To: LibWhacker

sounds like the author of the Harry Potter books was on occasion not writing about “magic” but instead reflecting quantum physics (whether she realized it or not)

the more humans know, the larger becomes the body of knowledge we are aware that we don’t know

the “undiscovered” universe (that portion of creation we either have no knowldge of or no understanding of or admittedly incomplete understanding of) seems to keep expanding as fast as what we do know grows - like peeling an onion with infinite layers


39 posted on 10/03/2012 6:40:42 PM PDT by Wuli
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To: 6SJ7; AdmSmith; AFPhys; Arkinsaw; allmost; aristotleman; autumnraine; Beowulf; Bones75; BroJoeK; ...

Thanks LibWhacker.

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40 posted on 10/03/2012 6:46:18 PM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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To: LibWhacker
Tardis Express: When it absolutely, positively has to get there yesterday!
41 posted on 10/03/2012 9:31:11 PM PDT by ADemocratNoMore (Jeepers, Freepers, where'd 'ya get those sleepers?. Pj people, exposing old media's lies.)
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To: LibWhacker

Ah, so the math is finally showing them that time has variable expressions, not merely linear. The planar nature of temporal reality has been right before them for a long time, in the phenomenon of quantum non-locality. Wait until they discover the volumetric nature of time. That should ruffle their ‘e’ ...


42 posted on 10/03/2012 10:30:00 PM PDT by MHGinTN (Being deceived can be cured.)
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To: LibWhacker

“When I was a graduate student, I proved the temporal order of events was relative; i.e., whether event A precedes event B or B precedes A in time depends on the frame of reference of the observer.”

-—<>-—<>-—<>-—<>-—<>-—

I taught a class in intro relativity and quantum mechanics for two semesters. When it came to that stuff I needed to stick strictly to the book or I would confuse myself due to that problem so much that it was really a danger that I would completely mess up my students. Frame of reference stuff seems like it should be so elementary until you start really getting into it, then it can become impossibly obtuse.


43 posted on 10/03/2012 11:03:08 PM PDT by AFPhys ((Praying for our troops, our citizens, that the Bible and Freedom become basis of the US law again))
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To: Chode
I knew someone would get Schrödinger into this thread.

If nobody did I would have :-)

44 posted on 10/04/2012 4:27:18 AM PDT by Condor51 (Si vis pacem, para bellum.)
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To: Condor51
yup... it was begging for it
45 posted on 10/04/2012 4:48:40 AM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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To: LibWhacker
Either way, THE UNIVERSE IS INSANE!

That explains a lot doesn't it? LOL

46 posted on 10/04/2012 12:34:24 PM PDT by TigersEye (dishonorabledisclosure.com - OPSEC (give them support))
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To: Chode
and the cat can be dead and alive at the same time...

One more reason I don't eat at the Peking Moon!

47 posted on 10/04/2012 12:36:33 PM PDT by TigersEye (dishonorabledisclosure.com - OPSEC (give them support))
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To: AFPhys
Frame of reference stuff seems like it should be so elementary until you start really getting into it, then it can become impossibly obtuse.

Yep, that's why I never told anyone else about it. I figured I had probably just made a mistake somewhere, though my friend couldn't find it, if so. And for the life of me, neither could I. Still, there was no way I was going to waltz off to one of my professors and suggest I had found something new! It's too easy to make a mistake and not realize it. Then you look like an idiot. Strange in a way because that's what math and physics are all about: making a million mistakes. That's how we learn. But you better not make that one or you're through.

48 posted on 10/04/2012 1:19:19 PM PDT by LibWhacker
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To: TigersEye
LOL!!!! great video...
49 posted on 10/04/2012 2:48:11 PM PDT by Chode (American Hedonist - *DTOM* -ww- NO Pity for the LAZY)
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