On Monday, June 29, 2020, 09:50:46 AM PDT, Karl <gmkarl@gmail.com> wrote:
>Jim put a lot of energy here into replying to a joke.

I'm not aware that:

"Scientists in China managed to exchange a crypto key at a distance of over 1,000 kilometers"

>"Wow!"

>"How can they do that?"

is a joke.

Actually this 50% a joke 50% serious, since the initial article did not mention anything about using Quantum Entanglement and so as such the challenged looked as if we were in ... 1820...

now for the 50% seriousity, I wonder how they can really use quantum entanglement at such a distance ... I am sceptical there and it would be marvelous if they really achieved what they claim they achieved... quantum entanglement over more than 1,000 km of distance... you flip a bit, it gets 'instantaneously' flipped on an other part of the world, located at 1,200 km distance, information without matter movement, at a speed (much) faster than light.

I got the explaination from Jim, still besides the obvious issues with the cables etc... such phenomenon as quantum entanglement relies on very complex experimentation and so I am not convinced at all that what they exchanged ( cryptohgraphic keys but in that context doesn't relaly matter ) was not used by "ordinary" communication, eg with matter displacement.