MaxTegmark

Thanks for bringing up the fun topic of free will! The free will issue becomes very interesting as soon as you assume that our universe is purely physical, regardless of whether you also assume that it's totally mathematical. If your decisions are made by computations in your brain that correspond to elementary particles moving around according to the deterministic laws of physics (and making you feel conscious in the process), then how can we understand why it feels like we have free will?

Philosophers have of course argued over this famous question for ages without reaching consensus. Quantum physicist Seth Lloyd has made the interesting argument that a brain (or computer) will feel that it has free will if it can't figure out what it will do a minute later in less than a minute, i.e., if there's no "shortcut" way of getting to the answer of the decision-making computation without actually making the whole computation. This agrees well with how I feel when I decide: I consider the consequences of my various options, weigh the pros and cons, etc., and don't know what I'm going to decide until I've finished thinking it all through.

My wife is here next to me laughing, and says "our first date was pretty magnetic"... :)

As described in https://arxiv.org/pdf/gr-qc/9702052.pdf and in my 1st book (http://mathematicaluniverse.org), you can't have stable atoms or solar systems if there are more than 3 spatial dimensions, you don't have gravitational attraction in less than 3, and you can't predict anything if there's more than 1 time dimension, making it pointless to have a brain. So if there's a multiverse where different parts have different dimensionality (as in many models with stringtheory + inflation, say), then you'd probably only have observers in parts with 3 space dimensions and one 1 time dimension - and here we are! :-)

I think that consciousness is the way information feels when being processed in certain complex ways. To me, the exciting remaining challenge is to clarify what precisely those "certain complex ways" are, so that we can predict which entities are conscious. :-)

I think that self-driving cars will eliminate the vast majority of of the 30000+ annual road deaths in the US. Of course there will be problems, but on the whole, less than with human drivers. They already drive better than I do on highways, which is, admittedly, not saying a lot... :-)