Fact and Fiction

Thoughts about a funny old world, and what is real, and what is not. Comments are welcome, but please keep them on topic.

Sunday, October 01, 2006

What's done is done, or is it?

There is an article by Patrick Barry entitled What's done is done, or is it? in this week's New Scientist, in which he discusses whether quantum mechanics allows the future to change the past.

Ho hum! Here we go again.

I debunked this whole class of phenomena (or, at least, the wrong interpretation(s) of them) in an earlier posting of mine called Spooky action at a distance?, where I showed exactly how QM explains the instantaneous communication that seems to occur between separated particles. Of course, there is no such instantaneous communication; any correlations between separated particles are explained entirely by the fact that they were in close contact at an earlier point in their history, together with the fact that the full QM description of the real physical state of the particles and the "observers" is a superposition of all of their allowed alternative states. For a detailed explanation of this see Spooky action at a distance?.

People love to imagine that QM is mysterious (remarkably, that includes the vast majority of physicists), and journalists take advantage of this weakness by writing articles like What's done is done, or is it?. I would prefer that we didn't encourage this sort of folk science, because it makes our thinking muddled, which makes it impossible to develop a correct shared understanding of QM.

If that sounds haughty, then I apologise, but this torrent of articles about "mysterious this" and "spooky that" tests my patience. Maybe I should write a popular science book to share my understanding of QM with others.

Update: That rant of mine seems to have scared you all off! Surely, I am not alone in feeling this way about the "reverential" treatment of QM in the popular press? As long as we insist on calling QM "spooky" and "mysterious" we will hold ourselves back from really understanding it.