Quantum entangled-photon Chinese satellite.

[Mirimir]

On 08/05/2016 02:29 PM, juan wrote:
> On Fri, 5 Aug 2016 13:56:15 -0600
> Mirimir <mirimir at riseup.net> wrote:
> 
>> First you create entangled electrons in two distant diamonds
>> [separated by 1.5 km in Hensen et al. (2015) and apparently 750 mi in
>> the Chinese-Austrian experiment described in the news article]. You
>> do that by exchanging photons, which travel at light-speed or less.
>> Then you measure the spins of those entangled electrons. And you find
>> that the spins are correlated in a way that's predicted by quantum
>> mechanics, but would be possible under classical mechanics (aka
>> realism) 
> 
> 	And full stop. You are not talking about physics. You are
> 	talking about bad philosophy. 

I'm just explaining what Hensen et al. (2015)
<https://arxiv.org/abs/1508.05949> reported. Read the damn paper if you
don't like my explanation. But read
<http://www.scottaaronson.com/blog/?p=2464> first ;)

> 	So, classical mechanics is realism. Fine. And the stuff the
> 	mainstream calls 'quantum mechanics' is what, then? Looks like
> 	it's not realism. So it is...bullshit.

The problem with classical mechanics is that it's not consistent with
measurements. Quantum mechanics is. The equations. According to the
Copenhagen interpretation, only the math matters. I don't like it any
more than you seem to. Because I'm not a mathematician.

But many worlds is very cool :) Read Stephenson's _Anathem_.

>> only if the entangled electrons could communicate at greater
>> than light-speed.
>>
>> So basically, they find that the classical model of reality is fucked.
> 
> 
> 	lol lol lol

You must be a local realist ;)

>> Here's the abstract from Hensen et al. (2015)
>> <https://arxiv.org/abs/1508.05949>:
>>
>>> For more than 80 years, the counterintuitive predictions of quantum
>>> theory have stimulated debate about the nature of reality. In his
>>> seminal work, John Bell proved that no theory of nature that obeys
>>> locality and realism can reproduce all the predictions of quantum
>>> theory. Bell showed that in any local realist theory the
>>> correlations between distant measurements satisfy an inequality
>>> and, moreover, that this inequality can be violated according to
>>> quantum theory. This provided a recipe for experimental tests of
>>> the fundamental principles underlying the laws of nature. In the
>>> past decades, numerous ingenious Bell inequality tests have been
>>> reported. However, because of experimental limitations, all
>>> experiments to date required additional assumptions to obtain a
>>> contradiction with local realism, resulting in loopholes. Here we
>>> report on a Bell experiment that is free of any such additional
>>> assumption and thus directly tests the principles underlying Bell's
>>> inequality. We employ an event-ready scheme that enables the
>>> generation of high-fidelity entanglement between distant electron
>>> spins. Efficient spin readout avoids the fair sampling assumption
>>> (detection loophole), while the use of fast random basis
>>> selection and readout combined with a spatial separation of 1.3
>>> km ensure the required locality conditions. We perform 245
>>> trials testing the CHSH-Bell inequality S≤2 and find S=2.42±0.20.
>>> A null hypothesis test yields a probability of p=0.039 that a
>>> local-realist model for space-like separated sites produces
>>> data with a violation at least as large as observed, even when
>>> allowing for memory in the devices. This result rules out large
>>> classes of local realist theories, and paves the way for
>>> implementing device-independent quantum-secure communication
>>> and randomness certification. 
>>
>> The news article is full of bullshit.
>>
>>> China apparently is putting this experiment in space - are they
>>> winning a game on prediction of one particular bit with > 75%
>>> probability, and if so, can they run that game numerous times to
>>> get that probability close to 100%, and if so, can the random
>>> inputs to each side be made not random so that the result of the
>>> game is transmission of information?
>>>
>>> I cannot begin to answer any of these questions sorry...
>>
>> As I understand it, they're just pushing the separation to 750 miles.
>> We're still a long way from transmitting useful data. And recall that
>> creating entanglement requires synchronization at light-speed or less.
>>
>>>> Me, I like the many worlds interpretation. But it's just an
>>>> interpretation. What matters is the math.
>>>
>>> That sounds much more interesting than the implications of 'dull'
>>> said to be arising from qubits :)
>>>
>>> The hope is that since some say the experiment is pretty dull to
>>> begin with, then perhaps there is a soul alive who could answer the
>>> above questions... we can only hope.
>>
>> In saying that it's dull, they're pointing out that what matters is
>> the math of quantum mechanics. It's just math. Equations. There's no
>> mental model, no story in words about how reality works. The
>> interpretations are just stories.
> 
> 
>