Quantum Measurement

I'm interested in the thought that an observer effects an event in quantum mechanics. What sort of observer are we talking about? Does a baby observing have the same effect? Or a dog? Or a video camera? Or does the aspect of mind somehow play a part?
- john gribben (age 40)

You can find real physicists who've given all possible answers to your questions. Most who think about these questions now think that the important change occurs when the events being 'measured' become 'entangled' with any large-scale phenomenon. That could be a video record, a tree falling in the forest, etc., in some way that depends on the quantum state of the 'measured' system. Once many things outside the small system land in different states (e.g. different video records) depending on the state of small system, then the different possibilities can't ever show more quantum interference. Whether that means that somehow the state collapses to only one outcome or that your mind, like any other device, splits into different non-interfering versions is a much-argued question.

Mike W.

(published on 03/18/2008)