What is entanglement really? And why is it that it's a uniquely quantum phenomena?

**Homework:**

- Explain why Alice can never send any messages through this set up.
- This is one to practice working with wavefunctions of several objects. Prove mathematically that itâ€™s impossible to write our state as two separate states for the electron and positron
- This one is very relevant to quantum computing. If you have just one electron or positron, you only need 2 numbers to describe its state. Now suppose you have n of them. If they are not entangled, how many numbers to you need to describe the state? What about for a general state that is allowed to be entangled?

**Bohmian mechanics stuff:** In Bohmian mechanics, you still have superpositions, they just mean something very different. A Bohmian mech particle only has one position, however, it still has a wavefunction that is a superposition of many possibilities. The difference is that the particle has one position but is influenced by other things in it's wavefunction. A particle like this behaves very differently to a classical particle that only has one position and is not at all influenced by it's other possibilities.