11–20 of 31 posts
Some time ago I thought how strange these all would look to someone who had no knowledge in physics at all. But then I got it: two particles in different galaxies being entangled is not much different from calling someone on the other side of the globe using a cellphone if you don't have prior knowledge/beliefes about either.
Can anyone explain (in layman-like terms) how one goes about transporting a single photon over a distance of 1.3km? I really like to have a general idea of the technology involved. "The researchers started with two unentangled electrons sitting in diamond crystals held in different labs on the Delft campus, 1.3 kilometres apart. Each electron was individually entangled with a photon, and both of those photons were th…
They use a optic fiber. This version has mare technical details, but is still understandable: http://arstechnica.com/science/2015/08/experiment-confirms-t... (HN: https://news.ycombinator.com/item?id=10141658 (4 points, 12 hours ago, 1 comment)) > To get around this, the researchers started with the diamonds over a kilometer apart in two different labs at the Delft University of Technology. They entangled each electr…
> The whole process was horribly inefficient, with a success rate of 6.4 × 10−9, mostly because photons kept getting lost in the fiber optic cables. But, over the course of nine days, the setup managed to successfully entangle the nitrogen vacancies 245 times.
My understanding is that entanglement doesn't actually allow for transfer any information faster than the speed of light but is more like having two coins sealed in a box and given to two parties, that "God" always keeps the same way up until they're opened. You can manipulate them by flipping the coins over, but you don't know what it was originally. You can open your box and see that your coin is heads, and send a…
What you've quoted there is a good analogy of an entangled state. In reality there are several differences, and the biggest piece of misinformation is that measurement of one system somehow "collapses a wave function" in the other system which isn't the case. The phenomenon of entanglement is that measurements of certain things are either perfectly correlated or anti-correlated. Eg. Measurement of spin along some axi…
The similarity to 2 coins is: if i have a 1972 coin and a 1973 coin
Earlier quoted context omitted.
What you've quoted there is a good analogy of an entangled state. In reality there are several differences, and the biggest piece of misinformation is that measurement of one system somehow "collapses a wave function" in the other system which isn't the case. The phenomenon of entanglement is that measurements of certain things are either perfectly correlated or anti-correlated. Eg. Measurement of spin along some axi…
The similarity to 2 coins is: if i have a 1972 coin and a 1973 coin What you have explained is "Quantum local hidden variable theory". Which has been proven wrong again and again. The article says this test has closed the last loopholes that made this theory a possibility. https://en.wikipedia.org/wiki/Local_hidden_variable_theory
The two coins metaphor illustrates the anti-correlation of two particles and why that doesn't allow faster-than-light communication. By observing one, you can deduce the other.
Of course it isn't a metaphor for the whole process, such that you can derive implications from the metaphor that will hold in the quantum case. But the point of the 'spooky action at a distance' is that there is no metaphor based in classical physics that can do so.
So physicists, and lecturers (in my limited experience) use metaphors to explain certain parts of the behavior.
It's like when a physicist talks about a quantum being a wave or a particle. Both are metaphors from classical physics. It is neither, and both metaphors only illuminate very specific properties.
The approach of saying 'that metaphor has been proved wrong', just leaves us with no way of explaining stuff. It is worth keep reinforcing that all metaphors are wrong, but your response seemed overly-negative to me.
Every time I read something on quantum theory I can't help but notice how close to notion of magic it feels like. And I've studied physics in college. Some time ago I thought how strange these all would look to someone who had no knowledge in physics at all. But then I got it: two particles in different galaxies being entangled is not much different from calling someone on the other side of the globe using a cellphon…
My understanding is that entanglement doesn't actually allow for transfer any information faster than the speed of light but is more like having two coins sealed in a box and given to two parties, that "God" always keeps the same way up until they're opened. You can manipulate them by flipping the coins over, but you don't know what it was originally. You can open your box and see that your coin is heads, and send a…
What you've quoted there is a good analogy of an entangled state. In reality there are several differences, and the biggest piece of misinformation is that measurement of one system somehow "collapses a wave function" in the other system which isn't the case. The phenomenon of entanglement is that measurements of certain things are either perfectly correlated or anti-correlated. Eg. Measurement of spin along some axi…
My understanding is that entanglement doesn't actually allow for transfer any information faster than the speed of light but is more like having two coins sealed in a box and given to two parties, that "God" always keeps the same way up until they're opened. You can manipulate them by flipping the coins over, but you don't know what it was originally. You can open your box and see that your coin is heads, and send a…
Take a coin and split it in two. One side has heads, the other has tails. The key thing is you don't look at the two halves.
Now, take one half at random, and send it to a person very far away. Too far away to communicate easily at light speed.
Then, have the other guy look at what he has. He will (of course) determine that it has either heads or tails. Which means (of course) that the one you have is the opposite, either tails or heads.
Nothing weird yet, right?
The quantum weirdness comes in when you start doing variations of the tests to see what state the coin halves are in before you do the final measurement.
It turns out that any model you can think of (hidden variables, etc.) has physical consequences. When you look for those physical consequences, you don't see them.
What does that mean?
In this case, your coin half and the other coin half are in an "indeterminate" state. They both have some properties of "heads" and they both have some properties of "tails". But their state is not determined. It really is an unknown state.
And why move one half far away?
Because you can do tricks where you both measure the coin halves at the same time, or near the same time. If (somehow) one measurement sent information from one coin to the other... that information has to transfer at light speed.
But it doesn't. When one half is measured, the other half instantly becomes the opposite state. So far as anyone can tell, this process is instantaneous. And any "communication" between the two halves has infinite speed.
The difficulty here is setting up systems so that they're isolated, and nothing interferes with the test. Then, doing all of the little measurements testing the edge conditions of your theory.
In short, everything you think you know is wrong. The coin halves really aren't anything until you look at one of them. Then, both of them instantly become determined as heads/tails.
Every time I read something on quantum theory I can't help but notice how close to notion of magic it feels like. And I've studied physics in college. Some time ago I thought how strange these all would look to someone who had no knowledge in physics at all. But then I got it: two particles in different galaxies being entangled is not much different from calling someone on the other side of the globe using a cellphon…
I see it as a failure of the model. When the explanation is irrational, does a scientist stop to wonder at the irrationality of the universe instead of trying to come up with better explanations?
It's easy to say "come up with better explanations". It's not very helpful, though.
Earlier quoted context omitted.
I see it as a failure of the model. When the explanation is irrational, does a scientist stop to wonder at the irrationality of the universe instead of trying to come up with better explanations?
Thousands of people have been trying for 50 years. Every model they've tried has turned out to be wrong. It's easy to say "come up with better explanations". It's not very helpful, though.
The purpose of criticism is not to be directly helpful by proposing better solutions, but to help eliminate the wrong ones.