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John Cramer to steer Mars rovers in real time

Asm

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Physicist John Cramer is planning a new experiment intended to test retrocausality:

http://seattlepi.nwsource.com/local/292378_timeguy15.html

Could someone please help me understand what he is actually trying to do here? How does it differ from say delayed choice experiments?

For the first phase of the experiment, to be started early next year, they will look for evidence of signaling between the entangled photons. Finding that would, by itself, represent a stunning achievement. Ultimately, the UW scientists hope to test for retrocausality -- evidence of a signal sent between photons backward in time.
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And unless the following statement is only a lose comparison, it sounds like he is talking about real information transfer:

"A NASA engineer on Earth could put on goggles and steer a Mars rover in real time," said Cramer, offering one example.
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Other quotes from the article, all by Cramer: "There's no obvious explanation why this won't work" ... "It doesn't seem like it should work, but on the other hand, I can't see what would prevent it from working" ... "It probably won't work".

It leaves me slightly confused...
 
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Hmm.
So. We receive the signal ... then, 50 microseconds later, we decide not to send it.
This looks like a perpetual motion, free energy, grandfather clock paradox.

ETA. Google " Bell's Inequality ", or " Alain Aspect". (Not "Alien". French).
If it makes any sense to you, come back and explain.
 
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The math explaining retrocausality is as tacked on as the verbal explanation, if you ask me. I seriously doubt anything travels back in time.

I think the experiment won't prove anything right.
 
Further grunting. The paper says:

Quantum theory describes the behavior of matter and energy at the atomic and subatomic levels, a level of reality where most of the more familiar Newtonian laws of physics (why planets spin, airplanes fly and baseballs curve) no longer apply.
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The writer and editors there don't know anything about the subject obviously. I bet they'd readily publish and put non-scientific ideas right next to science in equal footing.
 
Errm, Hello? You can't use entangled photons to send information. You can know something about a remote photon, but no information is transmittable. Unless they are talking about modulating this strange undiscovered signal some how.

By the way I didn't read the article link is broken, did /. cover it?
 
Ok, I Got the article to load,

I hope this section that describes the experiment is a fair use reposting: mods please delete if not.

In that final phase, one of the entangled photons will be sent through a slit screen to a detector that will register it as either a particle or a wave -- because, again, the photon can be either. The other photon will be sent toward two 10-kilometer (6.2-mile) spools of fiber optic cables before emerging to hit a movable detector, he said.

Adjusting the position of the detector that captures the second photon (the one sent through the cables) determines whether it is detected as a particle or a wave.

The trip through the optical cables also will delay the second photon relative to the first one by 50 microseconds, Cramer said.

Here's where it gets weird.

Because these two photons are entangled, the act of detecting the second as either a wave or a particle should simultaneously force the other photon to also change into either a wave or a particle. But that would have to happen to the first photon before it hits its detector -- which it will hit 50 microseconds before the second photon is detected.
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Yes this is an interesting experiment. Not quite sure how information would be transmitted though.
 
Here's some additional information from the article:

In that final phase, one of the entangled photons will be sent through a slit screen to a detector that will register it as either a particle or a wave -- because, again, the photon can be either. The other photon will be sent toward two 10-kilometer (6.2-mile) spools of fiber optic cables before emerging to hit a movable detector, he said.

Adjusting the position of the detector that captures the second photon (the one sent through the cables) determines whether it is detected as a particle or a wave.

The trip through the optical cables also will delay the second photon relative to the first one by 50 microseconds, Cramer said.

Here's where it gets weird.

Because these two photons are entangled, the act of detecting the second as either a wave or a particle should simultaneously force the other photon to also change into either a wave or a particle. But that would have to happen to the first photon before it hits its detector -- which it will hit 50 microseconds before the second photon is detected.
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It doesn't make much sense to me either. The last paragraph sounds kind of screwy. I know you can entangle two photons using polarization, but I've never heard of entanglement as wave vs. particle. It looks like the author may have got his quanum buzzwords confused.
 
It looks like the primate beat me to it.

Apparently, John Cramer is the author of what is known as the "Transactional Interpretation of Quantum Mechanics". I'm not sure if this is just an interpretation or whether it makes any physical predictions.

Heres a link to a summary: http://www.npl.washington.edu/npl/int_rep/ti_over/node2.html#SECTION00020000000000000000

This advanced-retarded handshake is the basis for the transactional interpretation of quantum mechanics. It is a two-way contract between the future and the past for the purpose of transferring energy, momentum, etc, while observing all of the conservation laws and quantization conditions imposed at the emitter/absorber terminating ``boundaries'' of the transaction. The transaction is explicitly nonlocal because the future is, in a limited way, affecting the past (at the level of enforcing correlations). It also alters the way in which we must look at physical phenomena. When we stand in the dark and look at a star a hundred light years away, not only have the retarded light waves from the star been traveling for a hundred years to reach our eyes, but the advanced waves generated by absorption processes within our eyes have reached a hundred years into the past, completing the transaction that permitted the star to shine in our direction.
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Could someone please help me understand what he is actually trying to do here?
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He's been tasked by congresswoman Sheila Jackson Lee to find the American flag.

Gene
 
It's a very interesting experiment, and I'm rather eager to know the results.

It appears that what he's testing is quantum entanglement itself really, with a time delay between detection of the two entangled particles.

He seems to be assuming that if the second particle is effected by the first, that it means the signal was sent back in time, to when the particles were entangled. While that is possible, it's also likely the particles share some undiscovered bond that we don't yet understand.

Frankly I think he's just going to find that two entangled particles behave as expected, though the underlying forces behind why are still being researched (which, this technically is a part of that research :) ).

As for signals in real time to Mars and beyond, while it's true that's an impossibility today, given our understanding of quantum entanglement, I'm of the mindset that humans have a rather annoying habit of finding solutions to impossible problems. There may come a day when we are capable of instant communication of this sort.
 
Crazycowbob said:
It's a very interesting experiment, and I'm rather eager to know the results.

It appears that what he's testing is quantum entanglement itself really, with a time delay between detection of the two entangled particles.

He seems to be assuming that if the second particle is effected by the first, that it means the signal was sent back in time, to when the particles were entangled. While that is possible, it's also likely the particles share some undiscovered bond that we don't yet understand.

Frankly I think he's just going to find that two entangled particles behave as expected, though the underlying forces behind why are still being researched (which, this technically is a part of that research :) ).

As for signals in real time to Mars and beyond, while it's true that's an impossibility today, given our understanding of quantum entanglement, I'm of the mindset that humans have a rather annoying habit of finding solutions to impossible problems. There may come a day when we are capable of instant communication of this sort.
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It sounds neat, but I can't figure out what distinguishes this from a standard delayed choice experiment.
 
Thanks for all comments and sorry for my late reply.

Soapy Sam said:
ETA. Google " Bell's Inequality ", or " Alain Aspect". (Not "Alien". French). If it makes any sense to you, come back and explain.
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Way over my head I am afraid (the technical bit, not the general idea)..

I misread the article as talking about quantum mechanics itself (the theory) and not Cramer's interpretation which I was not aware of (but of course should have checked before posting here..).

Crazycowbob said:
Frankly I think he's just going to find that two entangled particles behave as expected, though the underlying forces behind why are still being researched (which, this technically is a part of that research ).
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But he is apparently aiming to find corrobative support for his "Transactional Interpretation", maybe he will follow up with another experiment which the article doesn't mention?

By the way I didn't know that different interpretations of QM made different predictions or at least any testable ones. I thought it was clear in the maths and through numerous experiments with lasers and mirrors and stuff what QM can and cannot do.
 
Asm, John Gribbin is a well known author of various books of science to general public, his most famous book about quantum physics is; In Search for Schrodinger's Cat. He has a home site with a tabulation to the left which is labelled Quantum Mysteries, one of these is an improvement of The double slit experiment called the Quantum Erasier, this new experiment is able to erase the history which slit the photon has travelled through, and the experiment is described in John Cramer's Transactional Interpretation!

Deepening the quantum mysteries
http://www.lifesci.sussex.ac.uk/home/John_Gribbin/
 
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Peter Soderqvist said:
Asm, John Gribbin is a well known author of various books of science to general public, his most famous book about quantum physics is; In Search for Schrodinger's Cat. He has a home site with a tabulation to the left which is labelled Quantum Mysteries, one of these is an improvement of The double slit experiment called the Quantum Erasier, this new experiment is able to erase the history which slit the photon has travelled through, and the experiment is described in John Cramer's Transactional Interpretation!

Deepening the quantum mysteries
http://www.lifesci.sussex.ac.uk/home/John_Gribbin/
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A great link. Thanks!
 
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