Sean Carroll

But I think that even in that case, there's not a well-posed, what we would call in physics, an initial value problem.

That is to say, given the state of the universe, including your warp drive spaceship at one moment in time, how does it move around in the future?

It's more like a plausibility argument that you could, in principle, imagine something like this, even if we don't know how to actually make it happen.

We don't know how to make it happen, and the kind of technology involved in making it happen, even if not in what the UFO people are saying, but the sort of closest you could do in respectable science, is still so hilariously far away from what we're actually doing in technological reality that this is not something that I think is a high-priority thing for us to think about.

Let's put it that way.

David JS asks a priority question.

Remember that all Patreon supporters get once in their life to ask a priority question that I will do my best to try to answer.

And so David says, can you please take a few minutes to explain what philosophers mean when they talk about ontology and reality in relation to physics?

Are these terms rigorously defined?

I ask because I hear some claims that our underlying reality is a wave function in Hilbert space, yet I have never heard anyone claim that a high-dimensional classical phase space is real in anything like the same sense.

To my mind, both mathematical objects are just convenient constructions which allow us to calculate and allocate probabilities to outcomes in a rational way.

A common sense view of what is real might be that the world on a small scale is actually made up of particles or fields or whatever, whose behavior is what we would like to model.

Have I misunderstood what philosophers of science are saying when they use terms like ontology or reality?

So I'm not going to say a lot about reality because that's a contested field.

What counts as something real?

I mean, it's contested in many different ways.

Are mathematical objects real?

Are emergent higher-level structures real?

Is free will real, right?

It really just is both an issue of what is your view of how reality works and your view of what counts as real.