Friday, August 15, 2008

Quantum Entanglement

In 1935 Einstein wrote what might be considered his parting shot against quantum theory, his paper with Podolsky and Rosen describing entanglement. Einstein thought it highlighted the fact that quantum theory was incomplete or wrong, calling it "spooky action at a distance". Now more than 70 years later physicists are sure entanglement is a real phenomenon, its routinely produced in the laboratory and even being used in some futuristic practical applications like quantum computing.

But its not the practical applications that really interest me. What intrigues me is the notion that two physical entities in the universe can be connected across vast distances of space. I don't care what the quantum computer geeks say, so what if you can't transmit digital information instantaneously with entanglement? What really matters here in my opinion is the connection. The fact particles are connected in this way shows that the universe is a bit more mysterious-maybe way more mysterious-than we ever imagined.

In a recent article about this topic, which mentions (but did not describe in much detail) an experiment where scientists in Switzerland were looking to see if some signal traveled faster than the speed of light, a physicist named Nicolas Gisin remarks that nature seems able to "manifest events in multiple locations". Gisin goes on to assure us no signal can travel faster than the speed of light. Some have imagined that perhaps a faster-than-light signal connects two entangled particles.

I know there is a lot of evidence in support of special relativity-no reputable scientist disputes it and I'm not going to either. But let's not make it a religion. I think physicists are all too eager to dismiss the notion of a signal of some kind traveling faster than the speed of light. We don't want to be new age quacks but at the same time we need to keep an open mind. All too often in the history of science physicists just "knew" such and such was a fact and it turned out not to be. Maybe there are signals that can travel faster than the speed of light.

In any case, something is connecting the two entangled particles. Maybe they have some kind of link through higher dimensions.

Click here to read the article


rrtucci said...

Nice blog--we need more blogs by physicists (instead of impractical complexity theorists) on quantum information theory. I forgive you for a few posts on string theory :) My personal way of demystifying quantum mechanics is bayesian networks. I even wrote a free application called Quantum Fog on this. One can use bayesian networks to define quantum entanglement (see wikipedia article on squashed entanglement). Coolest of all, One can use bayesian networks and quantum computers to do AI (see this arxiv article)

GNH said...

Thanks for stopping by. I will be posting lots more comments on quantum information. But some on string theory too...