Objective state reduction (a better way to kill a cat?)

[rsa]

In this article, a new theory by Roger Penrose is discussed. Penrose proposes that gravity may be the answer to Schrödinger’s cat paradox. He argues that as the size of an object increases, differences in the gravitational energy of the superposed states causes an “objective state reduction” which causes a spontaneous collapse of the superposed states. The more massive the object, the more quicker the collapse. If correct, this would eliminate the need for observers, a near infinite multiplicity of splitting universes, or any of the other interpretations of quantum mechanics.

Penrose estimates that for an object the size and mass of a proton, a superposition of states can last for millions of years. Atoms and molecules would not last as long in superposition, but still far too long for the collapse to be measured. So far this agrees with Zeilinger’s experimental observations.
But long before an object contains enough atoms to span the thickness of a cat’s whisker, its large gravitational energy prevents a superposition from lasting longer than a millionth of a second. And so gravity explains why, much as you’d sometimes like to, you’ve never found yourself in two states or places at once-and neither would SchrÖdinger’s cat.

Is this theory just so much tilting at windmills, or is it possible that Penrose is on to something? Is he deceiving himself by refusing to accept quantum physics as it is? As for me, this theory fits very well with my “gut feeling” that we are still missing something.

[Whack-a-Mole]

I don’t see how Penrose is refusing to see Quantum Mechanics as it is with this. I think most people feel the Schrodinger Cat bit falls apart because it equates a macro system with a quantum system. Indeterminacy works fine at exceedingly micro scales but doesn’t work too well once you get much bigger. From my admittedly neophyte view Penrose seems to be merely trying to ‘prove’ why a macro system can’t have quantum sensibilities applied to it.

Is Penrose correct? I don’t know but Penrose is no slouch. While I’m sure he can be wrong far be it from to to suggest it.

[rsa]

I see your point, but there are not many good theories about why macroscopic objects should be different and many scientists don’t necessarily think they are different.

Zeilinger is equally convinced that they can exist-in principle, at least-right up to the scale of car keys. His research group has managed to fire a fullerene molecule, which contains sixty carbon atoms, through two separate apertures at once, demonstrating quantum superposition at a surprisingly large scale. Zeilinger is confident that as his experimental skills improve he’ll be able to put even larger things-like bacteria-into superpositions. And if it can happen to bacteria, why should cats be any different?

And in regards to the proposed experiment:

Bouwmeester is equally enthusiastic but, ironically, he thinks the experiment will ultimately prove Penrose wrong. “Personally, I think the effect will not be there,” he says. “Quantum mechanics is so simple and beautiful-although bizarre to the human mind-I think that what we will learn is that we should accept it as it is.”

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errata for the OP: more quicker = quicker (d’oh!)

[FriendRob]

A number of years back a paper by Ghirardi,Rimini, and Weber showed that it was possible, according to all experiments on Qm that had been done to date, that Qm was correct for small systems but for large systems something different was going on. They treated the “something different” as a spontaneous wavefunction collapse. Penrose suggest gravity as the cause of such a collapse.

I’m not sure of the current state of the GRW idea, but AFAK it is still possible. The good thing about ideas like this is they bive experimenters something definite to look for. I bet in the next 10-20 years we will know the answer to this.