Recently read: Quantum Enigma

This is the best introduction to Quantum theory that I've seen. The authors are not New Age gurus but scientists, and they write and think clearly, fairly, and are always clear about what is accepted by the scientific community and what is speculative. They use this as the textbook in their course at the University of California at Santa Cruz -- and what a wonderful course it must be! If you haven't read in this field, this is the first book to read.

The second book to read is Manjit Kumar's Quantum: Einstein, Bohr, and the Great Debate about the Nature of Reality, which casts the enigma in dramatic personal terms. I recommend both books without qualification.

Exerpts from the first book:

Quantum theory has been subject to challenging tests for eight decades. No prediction by the theory has ever been shown wrong. It is the most battle-tested theory in all of science—it has no competitors. Nevertheless, if you take the implications of the theory seriously, you confront an enigma. The theory tells us that the reality of the physical world depends on our observation of it. This is surely almost impossible to believe.

*

The waviness in a region is the probability of finding the object in that region. Be careful—the waviness is not the probability of the object being there. There's a crucial difference! The object was not there before you found it there. Your happening to find it there caused it to be there. This is tricky and the essence of the quantum enigma.

*

In principle, our world has a mysterious universal connectedness that goes beyond what we usually consider physical forces.

*

What's in the minds of the audience leaving the theater? If it's that physicists who use quantum mechanics spend their time dealing with the "spiritual revelations" the movie describes, we're embarrassed. If viewers think the physicists in the movie expressing these mystical ideas represent more than the very tiniest fraction of the physics community, they've been misled. The movie slides far down the slippery slope.

*

We find no "interpretations" of relativity. The more deeply you think about relativity, the less strange it seems. The more deeply you think about quantum mechanics, the more strange it seems.

*

The quantum theory works perfectly; no prediction of the theory has ever been shown in error. It is the theory basic to all physics, and thus to all science. One-third of our economy depends on products developed with it. For all practical purposes, we can be completely satisfied with it. But if you take quantum theory seriously beyond practical purposes, it has baffling implications.