Notes on Relativity and Cosmology - Physics Department, UCSB

CONTENTS 11
Maybe the following is a good way to look at it:
When reading the notes before class, the important thing is to identify the
questions. Then we can answer those questions in class.
I would also recommend bringing these notes to class, so that you can mark
them, underline things, and generally annotate the notes with what you learn
in class discussions. In particular, you may want to add color to some of the
black and white diagrams in the notes. Finally, you will want to use the notes
as a reference after class, reading through them again to iron out fine points
about which you are confused. Oh, and please do also make use of my office
hours so that I can help you with this process. I am told that the Wednesday
evening office hours are really, really useful.
Some parting comments
Our motto for the course: THINK DEEPLY OF SIMPLE THINGS.
I have shamelessly stolen this motto from one of my old professors (Arnold E.
Ross, Dept. of Mathematics, The Ohio State University 2 ). He used this for his
number theory course, but it applies at least as well to relativity. After all, what
will do is to spend the whole semester thinking about space and time. What
could be simpler and more familiar? We will have to work hard to notice many
important subtleties. We will need to think carefully about ‘obvious’ statements
to see if they are in fact true. After all, (in the words of a past student) your
view of reality is about to be ‘stood on its head and turned inside out.’
Let me provide one final piece of advise. At times, the ‘warped and twisted’
view of reality that emerges from relativity may cause some despair. Some
students feel that they ‘just can’t understand this stuff.’ Often, the greatest
obstacle a student faces in the quest for understanding is their idea of what it
means to ‘understand’ something. What does it mean to you? To some it means
to explain a new thing in terms of what they already know. Good luck with
this in relativity. You will not explain relativity in terms of what you already
‘know’ about reality because, quite frankly, what you think you ‘know’ is wrong.
Sorry, but that’s the way it goes.
Then, what do I mean by understanding relativity? Well, first let me agree
that obviously those things that you think you know about reality cannot be
completely wrong. After all, those ‘facts’ have served you well all of your life!
So, an important step is to grasp how all of the weird stuff of relativity is in
fact consistent with your life experiences to date.
But there is another big step in understanding relativity. Your current
‘knowledge’ of reality is deeply embedded in your intuition. It is a part of the
2 Arnold Ross died in the summer of 2002 at the age of 96. He actively taught mathematics
until after his 94th birthday.