Physics Pages

PhysicsPages contains my notes on various topics in physics. The site is fairly technical, in that I use whatever mathematics is required to explain the various topics. It is most useful to those who are either taking a structured course at a university or online, or to those who are working through a topic on their own. Although I've tried to make most articles self-contained with links to earlier posts, there is no substitute for a good textbook and/or an organized course. As such, I'd strongly recommend you buy a textbook and use that as your primary source. There are also many good courses available online for free at such sites as edX and coursera. There is a large collection of lectures on several areas of physics given by Leonard Susskind on his Theoretical Minimum site. The lecture notes of David Tong are also an excellent resource.

One final note: I have consciously avoided phrases like "obviously", "of course", "it is easy to see that" and so on, as in many cases they are bare-faced lies that appear all too often in textbooks. Many students find statements labelled this way as anything but obvious, and in my experience can cause a degree of frustration that often makes people abandon that particular book. If you do find any of these phrases in one of my posts, please do leave a comment and I'll try to remove it. (Sometimes I do say "it can be shown that", as in those cases it would take a post too far afield to include a derivation.)

If you're seeking help on some topic in physics that isn't covered here, you may find Physics Forums or Physics Stack Exchange helpful. Note that these sites do expect you to show that you've made some effort to solve the problem on your own before asking for help.

To get email notifications of new posts, you can sign up at the comments blog. You can also see new posts on Facebook and Twitter (just search for 'physicspages' on these sites and then click 'follow').

As always, comments and error reports are welcome, and can be sent to me at the comments blog.

Frequently Asked Questions
Books I've used

Search physicspages

To search physicspages, enter your search terms in the Custom Search box below. In the results, the top links may be ads, so just ignore them. This will search only within the physicspages site, so if you want an internet-wide search, use your usual search page. The search function should now show only those pages in the new physicspages site, but there could still be a few results relating to the old site that was taken offline. The first few results will probably be ads, so just ignore them.

Tables of contents

Electrodynamics Quantum mechanics
Quantum field theory Relativity
String theory Thermal physics
Group theory Astrophysics


I've removed the index pages as they contain the same links as the tables of contents above and it was wasted effort on my part maintaining both sets of pages. To find a post in the table of contents, use your browser's "find in page" feature in the relevant contents page. In Windows, this is Ctrl+F for Chrome, Firefox and Edge.


Here are a few photos of astronomical objects I've taken with an eVscope Equinox from my back garden.


I'm in the process of writing a series of tutorials on programming, which you can view here.

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