quantum mechanics - Is Schrödinger’s cat misleading? And what would happen if Planck constant is bigger?

Schrödinger’s cat, the thought experiment, makes it seem like as if measurement can cause a system to stop being in a superposition of states and become either one of the states (collapsed).

So does a system always exist in a superposition? In this sense, do things in the macroscopic world have a wavefunction? Is it because of the size of the everyday object, so it won't behave so much like an electron? Theoretically, if the Planck constant is to be bigger, everyday object would start behaving more like particles in a quantum scale?

Answer

In principle everything exists in a superposition of states. However everything interacts with it's environment, and this collapses the superposition through a mechanism called decoherence. In the particular case of Schrodinger's cat there is a brief discussion of this here. Also search this site for decoherence as there have been lots of questions about it.

For any system, like the cat, there is an associated decoherence time that tells you approximately how long it takes the superposition to collapse. For objects on the atomic scale this can be quite long, but for macroscopic objects the decoherence time is extremely short and we can never observe these objects to be in a superposition of states.

Someone has actually done an experiment to prepare a virus in a superposition of states . Because a virus is so much smaller than a cat the superposition can be observed. Luboš Motl has written a fascinating article about this on his blog.