# Where to start learning cosmology

1. Aug 13, 2015

### Entr0py

What are the prerequisites you need to have under your belt before you start studying cosmology? And frankly due to my naïveté, I'm not sure of any interdisciplinary fields in cosmology so I know my question is vague

2. Aug 13, 2015

### Chalnoth

It depends a little bit upon what level of depth, but to do any sort of calculations at all you'd need to at least have calculus under your belt.

To learn how to derive the basic equations (such as the Friedmann equations), you'd need some understanding of General Relativity.

In order to get into more complicated things such as structure formation you'd need to have a decent grasp of differential equations and series expansions.

3. Aug 13, 2015

### Entr0py

Thanks for the response. By the way do you know any good websites devoted to cosmology?

4. Aug 13, 2015

### Chronos

Math is the most vital ancillary skill. It will apply to almost everything cosmological. This article may be a useful primer: http://www.ams.org/samplings/feature-column/fcarc-cosmology. Without strong math skills, most modern cosmology papers are about as easy to understand as hieroglyphics. There is, of course, nothing to stop you from reading popular articles on cosmology, but, you will find yourself compelled to accept many things on faith, which becomes unsatisfying as your curiousity expands. For a nice collection of popular cosmology articles you might try http://www.astro.ucla.edu/~wright/cosmolog.htm. I try to avoid articles written by non-scientists. They tend to confuse as much as enlighten.

5. Aug 13, 2015

### ShayanJ

I thought for understanding early universe and inflation, its vital to know QFT(or QFT on curved ST?).

6. Aug 13, 2015

### Mordred

No QFT isn't needed to understand inflation. A good set of math skills and thermodynamics understanding is sufficient. Though GR does help along with QM.

The common formula used in inflation is the equations of state for scalar modelling. This is your thermodynamic portion. One major aspect in both GR and cosmology is both the FLRW metric and Einstein field equations employ the ideal gas laws.

The scalar modelling EOS can be found on this link.

https://en.m.wikipedia.org/wiki/Equation_of_state_(cosmology)

As mentioned before one needs to be able to employ the math, that math relies on differential geometry , strong statistical mechanics is also a good asset.

This site has 3 good preliminary textbooks.

http://www.feynmanlectures.caltech.edu/

Now as far as QFT itself is concerned, it's good to have some particle physics understanding in regards to inflation and Early universe dynamics. However the necessary details can be learned through either Quarks and Leptons

https://www.amazon.com/Quarks-Leptons-Introductory-Particle-Physics/dp/0471887412

or Griffiths Introductory to particle physics.

http://www.amazon.ca/Introduction-Elementary-Particles-David-Griffiths/dp/3527406018.

Here is two free resources. One being a full length free textbook.

http://arxiv.org/pdf/hep-th/0503203.pdf "Particle Physics and Inflationary Cosmology" by Andrei Linde
http://www.wiese.itp.unibe.ch/lectures/universe.pdf:" Particle Physics of the Early universe" by Uwe-Jens Wiese Thermodynamics, Big bang Nucleosynthesis

For the needed math in particle physics a good free resource is

http://arxiv.org/abs/0810.3328 A Simple Introduction to Particle Physics

http://arxiv.org/abs/0908.1395 part 2

The first book is primarily a coverage of differential geometry. 90+% of it, the second book steps you into GR.

GUT theories, are a bit trickier, in the coupling constants and is largely model dependant, (standard model vs SUSY and SO(10) , both MSM- minimial standard model or Minimal super symmetric ).

It's handy to be familiar with the basis of GUT but not necessarily required. Unless you wish to develop your own models.

Here is a decent coverage, the previous references will greatly help to understand this article.

http://pdg.lbl.gov/2011/reviews/rpp2011-rev-guts.pdf GRAND UNIFIED THEORIES

Two excellent intro level cosmology textbooks is Barbers Rydens Introductory to Cosmology.

http://www.amazon.ca/Introduction-Cosmology-Barbara-Ryden/dp/0805389121

and
Introduction to Cosmology by Matt Roose.
https://www.amazon.com/Introduction-Cosmology-Matts-Roos/dp/047084910X

Both are excellent entry low math intensive textbooks.

Modern Cosmology by Scott Dodelson
Requires greater math skills
https://www.amazon.com/Modern-Cosmology-Scott-Dodelson/dp/0122191412
As well as Physical Foundations of Cosmology by Muchanov.
http://www.amazon.ca/Physical-Foundations-Cosmology-Viatcheslav-Mukhanov/dp/0521563984

Last edited: Aug 13, 2015
7. Aug 14, 2015

### bapowell

I have to disagree with this. Sure, classical field theory is sufficient to understand the dynamics of the inflaton field itself, but we need QFT to study its fluctuations. Much research on inflation deals with these fluctuations and their effect on the CMB, so I'd say it's quite relevant. And I'd say that thermodynamics is not really necessary for understanding inflationary dynamics (though it's of course invaluable for early universe cosmology in general).

8. Aug 14, 2015

### Mordred

Agreed but the Op is looking for Where to begin to understand Cosmology. One doesn't need to fully understand QFT to understand the basics of inflation.

9. Aug 14, 2015

### Mordred

10. Aug 14, 2015

### Chalnoth

Yes, you do need QFT to do sensible inflation model building. But it's possible to grasp the simpler inflation models without that. QFT can also be good for understanding dark matter production and solutions to baryon asymmetry. I'd claim that all of these topics are quite advanced, however, and not necessary for somebody to get started in cosmology.

Not that QFT isn't itself very interesting, but it's also quite difficult.

11. Aug 16, 2015

### Entr0py

Awesome reply. Very informational

12. Aug 16, 2015

### marcus

I don't understand. If you are interested. If you are DRAWN to cosmology, and have some first year college calculus and physics, why wouldn't you start learning cosmology and see how much makes sense to you?

Why WAIT?

13. Aug 18, 2015

### Chronos

There are plenty of undergraduate astronomy courses at most universities. Many require calc I, but, not all. It is still a nice plus and you won't get very far without a firm math background..