On 13 May 2020 at 20:57, David Shaw wrote:

>
> While we're talking physics...
>
> Every description I've read, watched or heard about quantum
> entanglement says that, when you change the properties of one of the
> particles, the properties of the other instantaneously change,
> regardless of how far apart they are.
>
> Really? Instantaneous? Or do they mean 'at the speed of light which,
> given the scale of the experiments we've carried out is so quick that
> it is, for all practical purposes, instantaneous'?

Poor description all around.

You aren't *changing* properties.

You are measuring one of a pair of "related" properties. Until you
make the mesaurement said properties do not have a value. Really.
They've proved this experimentally via some interesting tests.

But measuring it on one particle means that since the particles are
entangled, the other one must have the same value. So it is
instantaneous.

It's an example of quantum non-locality.

And yes, the experiments ruled out "speed of light" changes too.

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com