Tobes' "Spooky action at a distance quantum weirdness headbands" got me thinking. Some of you guys seem (I say seem) to know something about this.
Maybe you can help me.

As I understand it "action at a distance" is a phenomenon predicted by quantum mechanics and verified by experiment. It involves a pair of particles (say photons) produced by the same event (say a proton clobbers a neutron) and fly apart at light speed. They are said to be "entangled particles". If one of the photons is interacted with its "probability wave collapses" and it declares itself as a particle with a few fundamental properties any one of which (and only one) can be measured. At the same instant it's entangled pair particle will experience a similar "probability wave collapse" and declare itself in a complementary condition to its pair. The spooky thing about it (Albert Einstein's word) is that there is no way for one particle to communicate with the other. Relativity says instantaneous communication over any distance is impossible.

However Relativity also tells us that as anything approaches the speed of light it's time slows and at the speed of light time stands still. A implication of this is that photons do not experience the passage of time. if you hold your hand out and catch a photon from the sun every geek knows that that photon has taken eight and a quarter minutes to get here so the photon is eight and a quarter minutes old. To the photon however no time has passed. It experiences its whole life path as an instant. Its beginning is the same moment as its end. If you could ask a photon what it is it would not say it was a point it would say it was a line, or rather in fact I think it would experience space as two dimensional and it would say it was a point in a two dimensional picture that includes all space. The point is that the photon IS a point smeared along its life path.

So those two entangled particles in their (equally valid) view of the situation are in fact still touching when their probability wave collapses so communication IS possible.

What's wrong with that notion? Don't all speak at once.

So how does a photon view life if it's going through a prism as part of its journey?

That would make it slow down slightly wouldn't it?

And if it has slowed down then time would start to flow?

It's all to hard for me, quantum stuff just makes me think that the physics department might have raided the chemistry department's 'top shelf'.

We need a geek subforum - reading this stuff makes my (admittedly small) brain hurt! [}:)]

Are you referring to the infamous double slit experiment?

Here is a video which describes it beautifully.

There might be some physicists who would like to know the answer too.
I think the famous phrase "If you think you understand quantum physics, then you don't understand quantum physics" applies, because it's all very unintuitive and weird.

Lawrence Krauss has given some accessible and interesting talks on cosmology which includes some quantum weirdness, my favourite is here

Every atom in your body came from a star that exploded. And the atoms in your left hand probably came from a different star than your right hand. It really is the most poetic thing I know about physics.

You are all stardust.

You couldn't be here if stars hadn't exploded. Because the elements, the carbon, nitrogen, oxygen, iron, all the things that matter for evolution weren't created at the beginning of time. They were created in the nuclear furnaces of stars. And the only way they could get into your body is if the stars were kind enough to explode.

So forget Jesus. The stars died so you could be here today.

tobes said...

NotWal said...

Tobes' "Spooky action at a distance quantum weirdness headbands" got me thinking.

Another satisfied customer.

is mine in the post??

doggie said...
is mine in the post??

You ordered the Spooky Action At A Distance Headband doggie.
One of our staff is wearing that for you right now, you should be feeling all the beneficial energies of a Quantum Wierdness Headband TM.
All thanks to the unexplained magic of Quantum Entanglement.

I'd love to explain it for you NotWal, but it's a secret recipe, like Coke, KFC, you know, all the good stuff.
(and just between you and me, I think in the future, they'll be laughing about Quantum and String theory, like we laugh about Earth being centre of the universe)

Maybe the Large Hadron Collider can help?

NotWal said...

Tobes' "Spooky action at a distance quantum weirdness headbands" got me thinking. Some of you guys seem (I say seem) to know something about this.
Maybe you can help me.

As I understand it "action at a distance" is a phenomenon predicted by quantum mechanics and verified by experiment. It involves a pair of particles (say photons) produced by the same event (say a proton clobbers a neutron) and fly apart at light speed. They are said to be "entangled particles". If one of the photons is interacted with its "probability wave collapses" and it declares itself as a particle with a few fundamental properties any one of which (and only one) can be measured. At the same instant it's entangled pair particle will experience a similar "probability wave collapse" and declare itself in a complementary condition to its pair. The spooky thing about it (Albert Einstein's word) is that there is no way for one particle to communicate with the other. Relativity says instantaneous communication over any distance is impossible.

However Relativity also tells us that as anything approaches the speed of light it's time slows and at the speed of light time stands still. A implication of this is that photons do not experience the passage of time. if you hold your hand out and catch a photon from the sun every geek knows that that photon has taken eight and a quarter minutes to get here so the photon is eight and a quarter minutes old. To the photon however no time has passed. It experiences its whole life path as an instant. Its beginning is the same moment as its end. If you could ask a photon what it is it would not say it was a point it would say it was a line, or rather in fact I think it would experience space as two dimensional and it would say it was a point in a two dimensional picture that includes all space. The point is that the photon IS a point smeared along its life path.

So those two entangled particles in their (equally valid) view of the situation are in fact still touching when their probability wave collapses so communication IS possible.

What's wrong with that notion? Don't all speak at once.

Action at a distance is to do with whether common causes screen off.

Tutor at uni Mauricio Saurez wrote about this. I remember it being one of the more "accessible" lecture units...

http://www.springerlink.com/content/u7064031u060j6u0/

then there's the whole time speeding up thing that the fringe quantum is talking about, as we move into a space which might be classed or seen as somewhat more enegetic A.T.M, but i guess for all youse with such a great handle on all things set in mainstream concrete, it would just be laughed off as conspiracy.

What are the possible explanations for the instantaneous communication?

1) Something is travelling faster than light.
2) Space-time is warped ...for the two particles.
3) Extra dimensions (string theory)
4) ???

I'm always amazed that the objects being studied are being studied by something made up of the objects, i.e. us. That is spooky.

The whole speed of light/time thing I thought I got, but the explanation I had was the "spaceship accelerating, message from front of ship to back at one second interval but taking less than a second between intervals therefore time is faster on sending clock because can't travel faster than light" analogy...

... but i hijack your thread. Another time.

NotWal said...
It implies of course that everything is comprised of 3d manifestations of hyper particles.

A bit like steam condensing?

If I had the time I'd go back to uni and study. I'll read on with interest. Will take me ...some lifetimes to digest ginger pom's post.

FlySurfer said...

Relativity doesn't apply to quantum mechanics. I guess the easiest way for you to understand quantum entanglement is that it is basically the same object viewed from different locations.

There are scientist developing quantum communication devices... this would allow real time communication with our robotic explorers.

I suggest you consult Wikipedia.

I did read somewhere that the phenomenon can't be used for communication because there is no way to control or predict the state the particles will adopt. I guess that's the basis of the external causality notion that ginger pom mentioned. But the collapse is caused locally isn't it.