Science a GoGo's Home Page Forums General Discussion Physics Forum Large scale QM effects

Tom Purdy and group of the University of Colorado have again extended the Quantum Domain to larger size now roughly 0.5mm

http://science.nbcnews.com/_news/2013/02...big-things?lite
http://www.newscientist.com/article/dn23177-sandgrainsized-drum-extends-reach-of-quantum-theory.html

Interesting news. But my main response isn't about the size of the object demonstrating uncertainty. It is about the definition of uncertainty they use in the article. I seem to recall reading that the description of uncertainty they use is slightly misleading. They are using precise measurements disturbing the thing being measured description. Just recently I read somewhere that that may be true, but it isn't quite the way uncertainty works. It is not just a matter of having your measurement disturb the object, it is that the object just isn't measurable, or something of the sort. I can't remember what it said, and I can't remember where I read it. Any way what it said is that it isn't quite as simple as that explanation.

Bill Gill

There are lots places (including P S books) where you could have read that, Bill.

On the Open University Science Foundation Course we were given the impression by at least one of the lecturers that uncertainty arose from the disturbance caused by measurement. That was in the early 1980s. It was wrong then, and it is still wrong now.

I suspect it is one of those “cop out” things. The thinking going something like: “most of there people are not going to become physicists, so a simple explanation will do. Those who are going further in physics will get a better explanation later”.

It’s not just in QM that this sort of thing happens. Some years ago, on a geology field trip to the Isle of Arran with the 6th Form (A level) geology students from the Harwich School, I pointed out to the tutor that an exposure he had been using for years to demonstrate a fining-up sequence to his students was in fact an ill defined fining-down sequence. His response was: “it’s good enough for this lot”.