Entanglement??

[WillieB]

A question to ponder:

This is about entanglement. Would it be inaccurate to state----

“Entangled particles are always created or influenced to possess exactly equal and opposite characteristics of spin, charge, and vector of momentum. Thus, when measured, irrespective of the distance between the points of measurement, it is not surprising that opposite characteristics will be discovered.” ????

[dleviwing]

Hi Willie;
The thing about entanglement is that it proves that the speed of light is not the ultimate velocity of the universe. As yet, an understanding of it is vague at best. It is best used to measure the quantum field properties of particles and not the physical aspects of the particles themselves.

[WillieB]

dleviwing--
Your comment forces me to reveal my abject ignorance when it comes to quantum mechanics. How do the physical aspects of a particle, its spin orientation and its momentum, vary from its field characteristoics in "quantumspeak?"

[Graybeard]

Dear WillieB .... QM basically says that 'spin orientation and its momentum' cannot be simultaneously known with absolute accuracy (Heisenberg's Uncertainty Principle). So how is it that by observing one of the entangled particles we can predict with accuracy exactly the properties of the other (how the other is behaving) ?

Einstein said that this is because the entangled particles were 'imprinted' with their properties prior to the time of their separation and therefore their properties can be known. (Einstein offered no explanation on how this imprinting occurs) This would seem to prove that QM is wrong, because QM says there is a degree of uncertainity about every particle and always will be.

The QM physicists dis-agreed with Einstein. This was the basis of the EPR paradox which was finally answered by an Irish Physicist named Bell and experimentally proved in the 60s.

It proved to everybodys satisfaction (or dis-satisfaction) that the Universe was not local. It subverts cause and effect. In other words QM was proved right (or as right). This means there are now 2 explanations for our Universe.

Which one do you favour ??

As Dave says, the two particles appear to be entangled ... that is, there is some commonality between them that exists faster than light could have transmitted any cause or effect between the two. This is a matter of interpretation as they do not break Einsteins rules regarding anything (such as information) exceeding the speed of light.

This is my own intrepretation, and Dave (DLeviwing) will correct me if I'm wrong. You would need to read up on Bell's Theorem, difficult if your just beginning.

Best of luck ... Greg

PS: I too, found Sanctus's explanation confusing ! I have a good book at home that explains this by analogy ... but at this moment I can't remember its name. if you post back here I will remember to look it up and put it in a reply post for you.

[WillieB]

Graybeard, Thanks for your input. Could that book possibly be Brian Greene's The Fabric of The Cosmos? Its a great book. I've read it carefully and I am still confused. Is it not true that all the entangled particles that have been investigated are created by the excitement of a single atom causing it to eject two photons in exactly opposite directions? If I am wrong please set me straight but if I am correct EPR was also correct in stating that these characteristics had been "imprinted" on the particles at their creation.

[Graybeard]

WillieB .... I think that is the book.

Is it not true that all the entangled particles that have been investigated are created by the excitement of a single atom causing it to eject two photons in exactly opposite directions?

I think you are right in the above quote ......... However, the fact that 2 photons are 'ejected' by the excitement of a single 'atom' ... in opposite directions..... does NOT allow the EPR paradox to claim that its ( EPR) explanation is correct. Your quote above does not imply your quote below. The answer is much more subtle

If I am wrong please set me straight but if I am correct EPR was also correct in stating that these characteristics had been "imprinted" on the particles at their creation.

Below is your initial statement that you requested verification of in the first post. The two sentences "Entangled ..... & "Thus..... can not be considered cause and effect.

“Entangled particles are always created or influenced to possess exactly equal and opposite characteristics of spin, charge, and vector of momentum. Thus, when measured, irrespective of the distance between the points of measurement, it is not surprising that opposite characteristics will be discovered.” ????

The book that you referred to, if it is the book I am thinking of .... and I apologise for not having looked it up yet ... has a chapter on entanglement. I also read it carefully, and I also was still confused ....

However, that chapter has a postscript that refers you to a more detailed explanation in the appendix (it could be postscript 7 ?).... THIS is where I finally came to understand the subtley of Bell's Theorem .... mind you it took me about a week of brain bending.The brain bending really consisted of turning the Maths into something I could conceive. The feeling when I grasped it was terrific ... better than sex, followed by cold beer on a very hot day.

I don't think I could do that explanation justice without revising it first. If you like I will revise this and see if I can come up with the explanation I supplied myself ??

Sanctus is also trying to supply from his memory, I can see by the fragments that he is on the right track, but zig-zagging wildly.

wait to hear from you ..... enjoying the post ... Greg

[dleviwing]

Hi Willie;
The key to entanglement is understanding the interpretation of the measurement. Particle physicist tend to call any quantitative measure of energy as being a particle. This leads to confusion in that the force particles are not physical nor are they local phenomena. If you think of a photon as an EVENT and not as a particle, it is much easier to visualize entanglement. The photon does not exist through space but is an event that occurs in space and thus it is only local when measured. By knowing the wave function of a force particle, we are able to predict when and where this event will occur. Bell’s theorem uses mathematics of wave mechanics that requires the cause of the event to occur at faster than light speed. (about 1.72c) Keep your focus on the measurement and what is being measured.

If you need to re-invent science to explain a theory, it is quite likely you’re wrong. Dr. Greene is full of it.

PS: Sorry for the delay in my response; My recovery from surgery is taking longer than I expected.

[austintorn@aol.com]

My attempt at a fuzzy subject:

Sub-Atomic Reality

Ever wonder what “reality” is really like at the sub-atomic level? Well, it’s quite strange and counter-intuitive—and it even hints of extra (or less) dimensions. Also, consciousness seems to be primary to, and “larger than”, matter itself.

Electrons have no trajectory, that is, they do not have a specific position and momentum at the same time; thus, they have no objective reality, whatsoever, as we know it. They don’t commit themselves to reality until we observe them—yes, the observer is not independent, as we would think, but, amazingly, creates reality through observation. The electron indeed then has a position (particle-like), if we chose to measure it that way, or, if we chose, a momentum (wavelike), but not both at the same time; yet, we can never know where the electron was just before an observation, and, so, there is a true randomness to nature (precluding omnipotence?).

When electrons are in their limbo of superposition, they exist in another dimension, which, to us would make it seem like they are everywhere and nowhere. An electron’s probability wave, like a crime wave, indicates only where it might be found. Electrons and photons have but a “fuzzy” reality until we collapse their probability wave by observing them with our consciousness. The observed and the observer are intimately related. Dimensional doorways may also explain how particle polarities, for example, can still correlate at great distances well beyond the reach of the speed of light—it’s as if magicians on Earth and in Andromeda could each pull out a King of Spades from their card decks at the same time. So perhaps the two particles are still the same particle at some deeper level of reality.

It seems that everything interpenetrates everything, as in a hologram. Perhaps this is why seeds can grow into trees from air and mud and sun, or embryos into babies; why memory works, why music seems to flow so smoothly, why . . .

[WillieB]

Graybeard:

Your last post, which I recived by e-mail hasn't yet appeared on this thread but I will reply here in any case.

I haven’t yet studied or even investigated the existence of the postscript to which you referred in that post. I promise that I will.

As to your statement that “…the fact that 2 photons are ‘ejected’ by the excitement of a single ‘atom’…in opposite directions…. does NOT allow the EPR paradox to claim that its (EPR) explanation is correct. …”

I made what I believe to be a logical assumption that… if two particles are ejected simultaneously from the same atom … those two particles will possess exactly equal and opposite characteristics of spin and momentum. If charge is involved the two particles will possess opposite charges.

I can’t prove or even immediately back up this assumption with quotes but it sure sounds logical to me. And if that assumption is correct…and, if my understanding of the method of creating entangled particles is correct, does that not make a case the good old boys, Einstein, Podolsky, and Rosen?

If understanding of entanglement can rival sex I should drop everything right now and rush to the books. At 78 any help at all is more than welcome.

Thanks for your participation here. I’ve really enjoyed it!

[WillieB]

To dleviwing and austintorn:

I am going to need need some time to wrap my brain around your last posts, particularly yours Dave. Not being at all familiar with wave mechanics makes it much tougher for me. Of course I am knowlegeable about wave/particle duality. Isn't it true that the act of measurement precipitates the collapse of the wave into a particle state?

Dave, I hope that your recovery is a speedy and complete one.

My Best, Bill