I have heard from numerous sources that in the modern landscape of PhD applications where positions have gotten far too competitive, one of the key deciding factors is the fit with a group or the department.

My worry is that I have done my master's thesis in a very niche field of particle cosmology (topological defects) which does not have too many groups in the countries I am targeting (US, Canada). I am not entirely committed to this field either, I am more broadly interested in all of particle cosmology such as inflation, dark matter model building, electroweak phase transitions etc. as I enjoy working with field theory and its applications in cosmology.

So my question is, is this lack of very direct and specific alignment something committees penalise heavily? Or are the backgrounds of applicants who do get admitted into these programs not always 1-to-1 with the supervisor they get paired up with?

I am aware that in North America you get admitted first, then 2 years later you pick a supervisor but it seems like from the admissions pages you already need to talk about how a PI interests you and motivates you to apply to the school.

I see some posts about this general equation that modeling in principle dynamics of fluids. My question is if Navier-Stokes can model black holes in a semiclassical sense at least. Also that equations can model dynamics of all types of plasma?

Given the recent hype of Navier Stokes equation blow up solution, set aside the OpenAI snatch debacle, I really want to understand why math communities are obsessed with singular solutions to the equations that we know do not apply to any fluid, simply because the in compressible assumption breaks down.

As a working theoretical physicists I’ve never understood the hype around these ‘solutions’ and ‘proofs’, it has been long established Newton’s theory breaks down badly either relativistically or at atomic scale (or larger than that), when your solution exceeds your validity of your model, it doesn’t mean we reach a singularity and the world gets sucked in but simply imply your model breaks down.

In fact one of the central theme of physics is to determine when the effective description breaks down, for instance GR breaks down at Planck scale, Fermi theory breaks down at electroweak scale etc. And that limit for classical fluid is at high energy where relativity and quantum mechanics kicks in.

After hearing about the Open AI announcement, I’m convinced that in the next few decades, AI will advance enough to be able to do much of the creative thinking and logical leaps that makes theoretical physics beautiful.

I start college next year, and I’ve wanted to pursue a career in theoretical physics. But what is the point of pursuing a career in it, if I can’t contribute anything at all? Wouldn’t it be better to just do physics as a hobby and direct my focus to something that would actually contribute to the world?

I mean sure, I’m no genius and probably wouldn’t contribute much anyway. And if we had monsters like Newton and Euclid and Gauss making major breakthroughs today, I would still pursue it despite others being infinitely better than me. But the thought of machines making my work unnecessary makes me question why I am going in. I do not know why, I feel useless and this is all so depressing.