A backward causality experiment is not really intended to explain time travel and its (im)probability, although this might be just a wonderful side-effect. Nonlocal quantum communication could instantly send information millions of light-years away and possibly even back in time.

Quantum entanglement is once again experimented with in the hopes of solving what Einstein theorized as "spooky action at a distance" almost a century ago. John Cramer, a physicist at the University of Washington, wants to test this theory and one of his controversial predictions about the possible effects of this entanglement.

Quantum theory predicts two subatomic particles derived from a single particle - like two photons split from a single photon - will, if not further influenced by other particles, continue to influence each other's behavior no matter how far apart.

What Cramer hopes to be able to do is split a photon, sending two "entangled" photons down to very different pathways of varying lengths using fiber-optic cables. Photons can exist in either particle or wave forms. The outcome can be manipulated by placement of detectors.

Since photons are entangled, the way one is detected, as a wave or as a photon, will cause the other to take one of the two forms. But Cramer wants to push this even further: if one photon were to travel a distance in space much longer that the other one, the latter would be delayed by a few microseconds.

And if the location of the detector for this delayed photon was changed to make it shift from wave to particle, wouldn't this mean that the other photon would have to assume the same shape? How can it do that, if it has already arrived at its destination?
Cramer says one explanation would be a backward time-travel. Although some physicists, like Stephen Hawking, said it wouldn't work, they could not produce a valid explanation of why it shouldn't. So, Cramer is anxious to find out.

And he's not the only one.