Quantum Entanglement Proven!
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24-09-2015, 07:08 PM
Quantum Entanglement Proven!
le article

EinsteinLaughat

(22-08-2015 07:30 PM)Revenant77x Wrote:  It is by will alone I set my brows in motion it is by the conditioner of avocado that the brows acquire volume the skin acquires spots the spots become a warning. It is by will alone I set my brows in motion.
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27-09-2015, 02:44 PM
RE: Quantum Entanglement Proven!
Sweet! We've been getting hints in the data (I'm reading, not researching) that this was going to be true. Einstein was wrong on some things, no big deal there. We all make mistakes. His legacy endures, regardless!
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27-09-2015, 04:59 PM
RE: Quantum Entanglement Proven!
(27-09-2015 02:44 PM)Fireball Wrote:  Sweet! We've been getting hints in the data (I'm reading, not researching) that this was going to be true. Einstein was wrong on some things, no big deal there. We all make mistakes. His legacy endures, regardless!

Of course! Not dumping on Einstein. Any scientist would be glad to be proven wrong. I just picked up a copy of his book on relativity the other day. For a scientist, he is a pretty easy going read

(22-08-2015 07:30 PM)Revenant77x Wrote:  It is by will alone I set my brows in motion it is by the conditioner of avocado that the brows acquire volume the skin acquires spots the spots become a warning. It is by will alone I set my brows in motion.
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27-09-2015, 05:21 PM (This post was last modified: 27-09-2015 06:58 PM by ZoraPrime.)
RE: Quantum Entanglement Proven!
(27-09-2015 02:44 PM)Fireball Wrote:  Sweet! We've been getting hints in the data (I'm reading, not researching) that this was going to be true. Einstein was wrong on some things, no big deal there. We all make mistakes. His legacy endures, regardless!

He wasn't exactly wrong.

Quantum entanglement has been known for awhile; I don't think Einstein was against entanglement per se. Rather, Einstein looked at a very curious consequence of entanglement and misinterpreted the action as violating relativity.

To be specific, when two electrons are created from two photons, angular momentum must be absolutely (i.e. not "on average") conserved (edit: this statement is wrong). Electrons can be prepared to have equal and opposite spins (in "an entangled state"). However, an electron in general will be created in a superposition of spins--you have a .5 chance of measuring "up" and measuring "down." However, measuring one "up" means the other will be measured as "down." This phenomenon is known as entanglement. Einstein's beef was that if someone measured their electron to be spin up; then they'd know that their partner (who, for the sake of argument, we assume is light-years away) will measure spin down. This came across to Einstein as faster-than-light communication violating. This process is often called the "EPR paradox," of which the first author is Einstein.

And everything about that is correct up until Einstein interpreting it as FTL communication. Since neither partner knows beforehand whether they'll measure up or down, they can't actually communicate anything meaningful faster-than-light. A more thorough analysis shows that this phenomenon didn't violate relativity; that's the only point Einstein got wrong. The EPR paradox was actually a great step forward in quantum theory, since the resolution of the paradox is whether or not the particle's spin was determined at creation (i.e. was the one measured to be spin-up always spin-up?) or whether it was determined at measurement; we can experimentally verify it's the latter case.

anyway, I guess that's that. I didn't bother looking at the article since I'm not sure what exactly was proved, given that entanglement per se has been known for a long time.

Edit: I wrote a wrong thing typing this a rush. There's probably some other small errors, even if the bulk of the information is correct.
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27-09-2015, 05:50 PM
RE: Quantum Entanglement Proven!
(27-09-2015 05:21 PM)ZoraPrime Wrote:  anyway, I guess that's that. I didn't bother looking at the article since I'm not sure what exactly was proved, given that entanglement per se has been known for a long time.

Quote:The experiment took time of nine days. In that time, scientists noted 245 positive entanglements. While other experiments over the last few decades have also maintained Bell’s limit, this new experiment acquires from their inadequacies to overcome experimental drawbacks. Previous test used incompetent detectors, only measuring a slight number of the particles passing through them. New experiments used near-perfect sensors, but the entangled particles were close enough to possibly connect. In the recent experiment, the team used high-quality sensors and measurements collected before the electrons could conceivably exchange signals with each other, creating it the first to close both loopholes.

Octapulse is too lazy to clip the relevant parts. Tongue

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27-09-2015, 06:22 PM
RE: Quantum Entanglement Proven!
(27-09-2015 05:21 PM)ZoraPrime Wrote:  
(27-09-2015 02:44 PM)Fireball Wrote:  Sweet! We've been getting hints in the data (I'm reading, not researching) that this was going to be true. Einstein was wrong on some things, no big deal there. We all make mistakes. His legacy endures, regardless!

He wasn't exactly wrong.

Quantum entanglement has been known for awhile; I don't think Einstein was against entanglement per se. Rather, Einstein looked at a very curious consequence of entanglement and misinterpreted the action as violating relativity.

To be specific, when two electrons are created from two photons, angular momentum must be absolutely (i.e. not "on average") conserved. The only way for this to be done is for the electrons to have equal and opposite spins. However, an electron in general will be created in a superposition of spins--you have a .5 chance of measuring "up" and measuring "down." However, measuring one "up" means the other will be measured as "down." This phenomenon is known as entanglement. Einstein's beef was that if someone measured their electron to be spin up; then they'd know that their partner (who, for the sake of argument, we assume is light-years away) will measure spin down. This came across to Einstein as faster-than-light communication violating. This process is often called the "EPR paradox," of which the first author is Einstein.

And everything about that is correct up until Einstein interpreting it as FTL communication. Since neither partner knows beforehand whether they'll measure up or down, they can't actually communicate anything meaningful faster-than-light. A more thorough analysis shows that this phenomenon didn't violate relativity; that's the only point Einstein got wrong. The EPR paradox was actually a great step forward in quantum theory, since the resolution of the paradox is whether or not the particle's spin was determined at creation (i.e. was the one measured to be spin-up always spin-up?) or whether it was determined at measurement; we can experimentally verify it's the latter case.

anyway, I guess that's that. I didn't bother looking at the article since I'm not sure what exactly was proved, given that entanglement per se has been known for a long time.

If one drops the odd idea of actual, physical superposition of states, there is no spooky action at a distance, nor any mystery to entanglement.

The superposition was, is now, and ever shall be, statistical.
Schrödinger's Cat was his response to what he saw as the absurdity of the physical interpretation of superposition, the Copenhagen interpretation.

I'm with Irwin on that. Thumbsup

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Science is not a subject, but a method.
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27-09-2015, 07:21 PM (This post was last modified: 27-09-2015 08:35 PM by ZoraPrime.)
RE: Quantum Entanglement Proven!
(27-09-2015 06:22 PM)Chas Wrote:  If one drops the odd idea of actual, physical superposition of states, there is no spooky action at a distance, nor any mystery to entanglement.

The superposition was, is now, and ever shall be, statistical.
Schrödinger's Cat was his response to what he saw as the absurdity of the physical interpretation of superposition, the Copenhagen interpretation.

I'm with Irwin on that. Thumbsup

Superposition seems absurd, but it seems very real. At this point, it's about the only thing in interpretations of quantum mechanics that has been agreed upon.

The reasoning is quite straightforward. If we assume that electron spin (along a particular direction) is binary, the theory of electron spin contradicts Bell's Inequality. Our assumption, that electron spin is binary, must have been wrong. This is resolved if we allow superposition, which means spin is no longer binary (it can be up, it can be down, or it can a superposition of both).

While it's not the most elegant explanation, Griffiths discusses Bell's Inequality in the afterword which is provided here. The last five minutes of the last lecture of MIT's Quantum Physics I video also provides an explanation, but it's probably hard to follow because it's the last five minutes of an entire lecture series. It's worth noting that the first lecture of this lecture series is all about superposition as a concept and doesn't involve mathematics (notes for first lecture are herw, if you'd rather read that: http://ocw.mit.edu/courses/physics/8-04-...ec01.pdf).

Edit: Looking over the Griffith's link again, it doesn't talk about superposition in as much detail as I thought. It discusses Bell's Inequality though, which just opens up a lot of experiments. Testing superposition and entanglement are the two most important of them.

Point is, the existence of superposition has been universally agreed upon by anyone quantum physicist I've seen. It just seems absurd because we don't see superposition states in real-life; i.e. every cat we observe is either dear or alive but never both. I do think though that it's real, because denial of superposition state means either the quantum theory of spin is wrong (unlikely--it agrees extremely well with experiment) or that Bell's Inequality is wrong (unlikely--it's just using basic logic of integers.
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27-09-2015, 09:42 PM (This post was last modified: 27-09-2015 10:06 PM by Ted Tucker.)
RE: Quantum Entanglement Proven!
All science is done by standing on the shoulders of giants.

"Only two things are infinite, the universe and human stupidity, and I'm not sure about the former." -Albert Einstein
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27-09-2015, 09:52 PM
RE: Quantum Entanglement Proven!
Nothing is really absurd to me, because I know nothing. So that was an interesting read.

What I learned was that if someone reaches over and tries to type on my keyboard, it's quantum!

I have a quantum nephew.

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