I guess it must be quite hard to get into theoretical cosmology (for a given school), but how does it compare to say, HEP theory?
Also, why do we not see many people applying to these fields? Aren't these supposed to be the most popular? (Granted, the popularity is stronger among high school students than senior undergrads, but even among senior undergrads aren't they quite popular?)
How competitive is theoretical cosmology?

 Posts: 30
 Joined: Mon Jan 14, 2013 4:22 pm
Re: How competitive is theoretical cosmology?
I'm not sure I've had the same high school/college experiences as you because I don't see theoretical cosmology being very popular at all. We didn't even learn cosmology (other than something called the Big Bang happened) at all in high school.
At the senior undergrad level, the cosmology course (labelled as Astronomy 4xx) was the most popular astronomy class by far, since it requires no astronomical background (it's truly a physics course, but just offered by astronomy faculty). However popularity of the course is not correlated with actual research interest  most students took it as an "elective", not as part of their research interests.
I'm also operating under the assumption that by theoretical cosmology, you mean working with models derived from General Relativity (e.g. EinsteindeSitter Universe, working with different spacetime metrics, curvature etc.). I've found that many people, like myself, are more interested in cosmology from a "popular" standpoint (i.e. just knowing the big pictures and competing models) but are turned off by the heavy duty math / geometry required to pursue it at the research level.
I think it's hard(er) to get into theoretical cosmology because, first of all, it's a theory field. Experiments usually get more funding and in general theory is more popular than experiment, from what I've seen. Also, I think it's easy to identify a strong experimental student from their background  working with certain equipment will surely develop certain skills. But it might be harder to identify a strong theory student  sometimes good grades do not necessarily translate into strong research ability.
Also, in my opinion, I don't see very many departments focused on theoretical cosmology. They exist at big schools, but I think smaller / lower tier schools tend to focus on more "traditional" physics (but correct me if I'm wrong!). At the smaller schools, there might only be 1 or 2 profs working on the topic so there are fewer spots for students who are interested! In addition, it's kind of somewhere in between Physics and Astronomy so "inbetween" fields like that have the danger of being less favoured by both departments when budgets are tighter etc.
At the senior undergrad level, the cosmology course (labelled as Astronomy 4xx) was the most popular astronomy class by far, since it requires no astronomical background (it's truly a physics course, but just offered by astronomy faculty). However popularity of the course is not correlated with actual research interest  most students took it as an "elective", not as part of their research interests.
I'm also operating under the assumption that by theoretical cosmology, you mean working with models derived from General Relativity (e.g. EinsteindeSitter Universe, working with different spacetime metrics, curvature etc.). I've found that many people, like myself, are more interested in cosmology from a "popular" standpoint (i.e. just knowing the big pictures and competing models) but are turned off by the heavy duty math / geometry required to pursue it at the research level.
I think it's hard(er) to get into theoretical cosmology because, first of all, it's a theory field. Experiments usually get more funding and in general theory is more popular than experiment, from what I've seen. Also, I think it's easy to identify a strong experimental student from their background  working with certain equipment will surely develop certain skills. But it might be harder to identify a strong theory student  sometimes good grades do not necessarily translate into strong research ability.
Also, in my opinion, I don't see very many departments focused on theoretical cosmology. They exist at big schools, but I think smaller / lower tier schools tend to focus on more "traditional" physics (but correct me if I'm wrong!). At the smaller schools, there might only be 1 or 2 profs working on the topic so there are fewer spots for students who are interested! In addition, it's kind of somewhere in between Physics and Astronomy so "inbetween" fields like that have the danger of being less favoured by both departments when budgets are tighter etc.

 Posts: 1203
 Joined: Sat Nov 07, 2009 11:44 am
Re: How competitive is theoretical cosmology?
It depends on what you mean by theoretical cosmology. I'll give a list of what I see as the breakdown of the subject, along with a number between 1 and 5 from 1 = extremely competitive to 5 = relatively open to new applicants.
String Theory, (theoretically motivated) models of inflation, other Unified Theory disciplines (quantum gravity, etc), and The Big Questions (time's arrow, causality, 'the beginning', initial conditions, and the flatness problem). The 'Stephen Hawking' definition of cosmology, perhaps. Normally this is essentially high energy physics (or in the case of The Big Questions, quantitative philosophy), where you pay attention to what cosmological data tell you when you invent your models. Found mostly in mathematical physics departments, or perhaps on the HEP floor, but is speculative in the sense that any real cosmological data on these questions are some years out. This is a 12, since there's no money, and the money that there is almost exclusively goes to postdocs who have a better handle on the advanced mathematics required.
Traditional 'theoretical cosmology'. Cosmological modeling, building theoretical (computational) models for traditional cosmological observables (CMB, matter power spectrum, supernovae, clustering, etc). Investigating extensions to the standard cosmological (LCDM) model of the universe, and how these extensions would affect observables, as well as phenomenological models of inflation. May also include some data postprocessing, beyond the basic statistical methods an observer will employ. Basically, the questions you'd find in a modern cosmology textbook. This is a 24, since often you can get paid off of observational grants.
Post analysis of observational data. It's similar to the above, but more nittygritty. Use standard (and extended) cosmological models to tease out more (modeldependent) information from datasets by backtracing cosmological evolution of the signal photons. Gravitational lensing, but also things like matter field reconstruction, the SunyaevZel'dovich effect for cluster counting, etc. I'd also include in this category inventing/working out the details of new cosmological observables, like cosmic shear. I'd say this is a 45, since you can almost always get on observational grants for this one, and it has obvious shortterm applications.
String Theory, (theoretically motivated) models of inflation, other Unified Theory disciplines (quantum gravity, etc), and The Big Questions (time's arrow, causality, 'the beginning', initial conditions, and the flatness problem). The 'Stephen Hawking' definition of cosmology, perhaps. Normally this is essentially high energy physics (or in the case of The Big Questions, quantitative philosophy), where you pay attention to what cosmological data tell you when you invent your models. Found mostly in mathematical physics departments, or perhaps on the HEP floor, but is speculative in the sense that any real cosmological data on these questions are some years out. This is a 12, since there's no money, and the money that there is almost exclusively goes to postdocs who have a better handle on the advanced mathematics required.
Traditional 'theoretical cosmology'. Cosmological modeling, building theoretical (computational) models for traditional cosmological observables (CMB, matter power spectrum, supernovae, clustering, etc). Investigating extensions to the standard cosmological (LCDM) model of the universe, and how these extensions would affect observables, as well as phenomenological models of inflation. May also include some data postprocessing, beyond the basic statistical methods an observer will employ. Basically, the questions you'd find in a modern cosmology textbook. This is a 24, since often you can get paid off of observational grants.
Post analysis of observational data. It's similar to the above, but more nittygritty. Use standard (and extended) cosmological models to tease out more (modeldependent) information from datasets by backtracing cosmological evolution of the signal photons. Gravitational lensing, but also things like matter field reconstruction, the SunyaevZel'dovich effect for cluster counting, etc. I'd also include in this category inventing/working out the details of new cosmological observables, like cosmic shear. I'd say this is a 45, since you can almost always get on observational grants for this one, and it has obvious shortterm applications.

 Posts: 30
 Joined: Mon Jan 14, 2013 4:22 pm
Re: How competitive is theoretical cosmology?
Thanks for your responses. And I meant all of them (on bfollinprm's list), so it's well that you've broken them down into each.
Re: How competitive is theoretical cosmology?
I should mention that I used to be in a dept with a fairly active theoretical cosmology group, and it was fairly competitive just because the profs in it would only have 12 students at a time. So even if you accept two theory students a year well guess what, only one of you is going to get the job if that.
But then I guess this is a fairly normal thing in theory to begin with.
But then I guess this is a fairly normal thing in theory to begin with.

 Posts: 1203
 Joined: Sat Nov 07, 2009 11:44 am
Re: How competitive is theoretical cosmology?
And fortunately for the OP, cosmology is not as popular as, say, HET, so 12 acceptances/yr isn't that odd. Though currently in my year there are 4 of us in cosmology theory at Davis (25% of the class) and only one of us has to TA.Andromeda wrote:I should mention that I used to be in a dept with a fairly active theoretical cosmology group, and it was fairly competitive just because the profs in it would only have 12 students at a time. So even if you accept two theory students a year well guess what, only one of you is going to get the job if that.
But then I guess this is a fairly normal thing in theory to begin with.