22 June 2008

Observer Created Reality

There's a good article up on Science Blogs about quantum mechanics. It is written for the lay-reader, which makes it rather long, but most people should be able to follow it. I wish there had been a few more technical details. In a nutshell, if quantum mechanics is correct either locality (localization of phenomena; "distant events do not affect one [an]other") or realism (properties exist before they are measured) must be incorrect. Someone finally came up with a test for realism, and the results were many orders of magnitude off from what a theory preserving realism would predict.

One quote from the end of the article:

Late last year Brukner and Kofler showed that it does not matter how many particles are around, or how large an object is, quantum mechanics always holds true. The reason we see our world as we do is because of what we use to observe it. The human body is a just barely adequate measuring device. Quantum mechanics does not always wash itself out, but to observe its effects for larger and larger objects we would need more and more accurate measurement devices. We just do not have the sensitivity to observe the quantum effects around us. In essence we do create the classical world we perceive, and as Brukner said, "There could be other classical worlds completely different from ours."

Read the whole thing

One thing that I'm not following. If the way we observe things as human beings determines how we see them (a blue couch is always blue is the example in the article), and quantum effects remain but we just can't see them, why is the couch always blue? Fine, our eyes "collapse the wave function" in some predictable manner, but, lacking realism, there doesn't seem to be any reason why they would always collapse it to the same value. Yet we observe couches that, most of the time, have the same color from moment to moment and day to day and year to year (minus fading, etc.) and we are surprised by exceptions. As the article is written for the layman, it may just be that some crucial aspect got left out, or it may be that no one's quite sure yet.

Ah, I found a few more details here, from someone advocating a "Transactional Interpretation" of Quantum mechanics. If you've got a Powerpoint viewer, there's a nice presentation of it here, or there's a much shorter discussion on Wikipedia. The interpretation argues for energy waves travelling both backwards and forwards in time. It seems to utilize non-locality, and argue that results are determined atemporally by "handshakes" between all entities involved in a quantum mechanical system. It's one that I hadn't encountered before.

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