What is an observable exactly?

[dsaun777]

What is an observable exactly? I hear terms that are used in physics books like an observable or a detection. What types of equipment do physicists use to make all these quantum measurements that are used in books so frequently? How small of a region of space does the wave function "collapse" into when measuring particles?

 

[DennisN]

How small of a region of space does the wave function "collapse" into when measuring particles?

Whether wave function collapse happens at all is an open question (different interpretations of quantum mechanics say different things on this topic).

 

[DennisN]

What types of equipment do physicists use to make all these quantum measurements that are used in books so frequently?

One example of equipment is photodetectors. But there are other types of equipment used, depending on what is studied. Examples of additional equipment: magnets, polarizers, waveplates etc.

 

[TeethWhitener]

Technically, an observable is just a Hermitian operator on whatever Hilbert space you're working in.