Last week I wasted a happy hour at the local bookstore flipping through Quantum Mechanics: The Theoretical Minimum by Leonard Susskind and Art Friedman. While it's definitely a book for people who have some math background, it doesn't require much and it unspools the basics slowly, thoughtfully and with exceptional clarity.
In the introduction, the authors ask the question: "What makes quantum mechanics special?" This is another way of asking: What makes quantum mechanics weird?
That got me thinking about the difference between quantum objects that appear in the micro-world (atoms, molecules and below) and the classical stuff we are used to up here in the macro-world. But even asking that question leads you to an even more basic question: What do you mean by an "object" in physics?
Our commonsense intuition about what constitutes "a thing" is pretty much what we get in classical physics. This most basic definition gets wiggy when we step into quantum systems.
Or, better yet, it gets wavy.
For quantum mechanics, any definition of what constitutes an object has to deal with the wave-particle duality. And that topic takes us on our first step down into true quantum weirdness. So, with that in mind I give you this nice MinutePhysics exploration of the venerable wave-particle duality.
And mind that first step. It is a doozy.