Hello everyone, welcome to the Mindscape podcast. I'm your host Sean Carroll.

Today's podcast is one of those long awaited episodes. People have been asking for this one for a long time.

You know, it's funny. Sometimes there are some possible guests who are just so obviously Mindscape guests

and I haven't had them on yet and people are like, well, what's wrong? Why doesn't he have them on yet? They must be feuding.

There must be beef or something like that. That's not usually the correct answer. It's usually just that I'd like to space them out.

As I've said many times, I like to have a variety and that includes both people who I know very well and am familiar with their work

and people I've never heard of before I got to looking for podcast guests.

So Tim Maul then is someone I've known for a long time. Is a leader in the philosophy of physics or what we sometimes call the foundations of physics.

So studying not physics as a philosopher, but studying nature as a philosopher, but doing so in such a way that you're looking at the foundational questions of nature.

You're asking the why questions, the deep questions you're trying to be very careful.

And Tim has done very important work in thinking about space time and the geometry of space time, the nature of time and the arrow of time.

I will point to, I will try to link in the show notes to a wonderful mock debate that was done at the foundational questions institute between Tim and Julian Barber.

Julian Barber famously has advocated that time does not exist. Tim is famously advocated that not only does time exist, but the arrow of time is fundamental, not just an emergent approximation because of statistical mechanics.

And what FQXI does is it has the debaters flip sides. So Julian was arguing in favor of the existence of time, Tim was arguing against it, and they were both really, really good.

I got to say they were both quite persuasive for the points of view they didn't actually agree with as well as being quite amusing along the way.

But today we're actually going to be talking about quantum mechanics. In some sense, this can be thought of as a sequel to the podcast that did a while back with David Albert talking about quantum mechanics.

David and Tim are very good friends and a poor together for a long time. They don't agree on everything because no two philosophers agree on everything.

But they are united in their skepticism about the effort interpretation of quantum mechanics. And so with David on the podcast, even though I'm pro-evert, I want to give the voice to sensible voices on the other side, sensible points of view.

And so David explained why he doesn't like the effort interpretation. What we didn't get to right at a time was what he does like.

So today with Tim, we're going to be talking mostly about Bomean or De Broglie Bome versions of quantum mechanics, sometimes called hidden variable versions of quantum mechanics.

I keep calling them hidden variable theories as most people do, even though as advocates like to point out, the variables are not hidden.

The extra variables that you add to quantum mechanics to make a hidden variable theory are the ones that you observe when you actually make a measurement.

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