Quantum mechanics itself cannot explain this problem. This has long been considered a worrying sign of a potential conceptual flaw in QM itself. Hence the ongoing interest in the Cat.
New Scientist has an interesting recent article on Schrodinger’s Cat: http://www.newscientist.com/article/mg21228363.600-quantum-upgrade-removes-need-for-spooky-observer.html
As that though-experiment shows, it’s really hard to make physical sense of quantum mechanics. If QM is true at the sub-microscopic scale –which seems true enough- then why does it not apply to the macroscopic world in which we live? As Schrodinger asks, why does something like a cat not show quantum behaviour? Why is the cat not in a superposition of dead and alive states?
No-one has been able to answer that. Correction, people have been able to answer it, but only by shifting the problem out of the physical domain. Thus one solution, and perhaps the most popular at present, is Everett’s many-worlds-theory, where all the possible outcomes do occur, but each in another universe. As a theory goes it obviously has the major problem of being non-physical. You cannot measure or interact with these other universes. So it is a solution beyond our physical domain: a metaphysical solution. (And just think, who is keeping track of all the information in all these infinity of universes?)
Other than that, there really isn’t much else in conventional physics as an explanation. For some alterantive perspectives, see this vixra list.
The cordus conjecture answers this question very easily, and using a physically natural explanation. It explains what’s happening in the Schrodinger’s Cat situation, and why we don’t see undead cats. It also explains why QM does not scale up to the macroscopic level.
Of course cordus is radical in its own way, in that it disagrees with the conventional QM assumption that particles are zero-dimensional points, and instead proposes they are two-ended structures. While the cordus structure may be strange, it is not metaphysical. So the cordus explanation stays firmly in the physical domain.
Read the full paper here: Why does quantum mechanics not scale up? http://vixra.org/pdf/1107.0019v1.pdf . It is pretty much a maths-free explanation, so anyone with a basic education should be able to get something out of it.
- What is Erwin Schrödinger associated with (wiki.answers.com)
- Quantum mechanics difficult to grasp? Too bad (newscientist.com)
- One-Minute Physics: Schrödinger’s Cat [Video] (geeksaresexy.net)
- Physicists seek to quantify macroscopic quantum states (physorg.com)
- Testing the Copenhagen interpretation: a matter of live and dead cats (telegraph.co.uk)