Quantum quandary

In Cambridge one of the speakers at the journalism fellowship I’m on was Keith Ward, an emeritus professor of theology at Oxford. In answer to a question that was skeptical about his assertion that the resurrection of Jesus was logically possible, Ward said:

Martin Rees [a prominent cosmologist] says there’s a possibility we can decant through a worm hole into another universe. When physicists talk like that, I think theologians can say what they like.

Here’s another cosmologist, Paul Davies, being interviewed at Salon (by Steve Paulson, who was a Templeton-Cambridge journalism fellow last year). In the interview, We are meant to be here, Davies goes quantum crazy on us. He argues that we may have influenced the physical laws of the universe just by observing them.

Here’s an excerpt:

Salon: This sounds like it’s coming right out of science fiction. Somehow, future people can go back in time and have some role in creating the universe. It’s pretty far-fetched.

Davies: It is pretty far-fetched until you stop to think that there is nothing in the laws of physics that singles out one direction of time over another. The laws of physics work forward in time and backward in time equally well. Wheeler was one of the pioneers of this underlying time symmetry in the laws of physics. So he was steeped in the fact that we shouldn’t be prejudiced between past and future when it comes to causation. The particular mechanism that Wheeler had in mind has to do with quantum physics. Now, quantum physics is based on Heisenberg’s uncertainty principle. In its usual formulation, it means that there’s some uncertainty at a later time how an atom is going to behave. You might be able to predict the betting odds that the atom will do this or that, but you can’t know for certain in advance what’s going to happen. Now, this uncertainty principle works both ways in time. There’s no doubt about this. If we make an observation of an atom in a certain state now, then its past is uncertain just as its future is uncertain.

So one way to think about this is that there will be many past histories that will lead up to the present state of the universe. In the remote past, its state was fuzzy. Now in the lab, it’s all very well to put an atom in a certain state and experiment on it at a later time. But when we’re applying quantum physics to the whole universe, we simply can’t establish the universe in a well-defined quantum state at the beginning and make observations later. We’re here and now. So we can only infer backward in time. It’s part of conventional quantum mechanics that you can make observations now that will affect the nature of reality as it was in the past. You can’t use it to send signals back into the past. You can’t send information back into the past. But the nature of the quantum state in the past can’t be separated from the nature of the quantum state in the present.

It’s way over my head, or under it, or in another universe from it.