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As mentioned on the front page, the target
audience for this website is amateurs -- people who are interested in
physics, and are interested in relativity, but who are not professional
physicists.
It is my fond hope that this site may help some visitors to better
understand the subject of relativity, or at the least will provide some
interesting reading.
About Relativity ... And Some Advice
The goal of relativity is to render all physical laws in a form which
is relative to the observer: the laws should be independent of
any motion of the observer or (in the case of radiant energy) of the
source. Special relativity treats the special case of uniform
motion; general relativity treats the more general case of accelerated
motion. General relativity also provides an answer to the
question, "Why are inertial and gravitational mass always present in a
fixed ratio?" or, equivalently, "Why does everything fall at
the same rate?"
If you are setting out to learn relativity, then I have a bit of
hard-won advice. Start by asking yourself:
How's your
algebra? Pick one:
- Rock solid! I invert matrices in my head for fun!
- OK, I guess.
- Boy I hated that subject -- skipped all the homework and just
crammed for exams
- Algebra? Huh? You mean, like the quadratic formula 'n
stuff?
If you answered (3) or (4), go find an algebra book and spend some time
with it. Artin's "Algebra" is pretty readable, if you haven't
already got a good text lying around. Ideally you should at least
know what a symmetric 2-form is before you tackle relativity.
GR requires tensor calculus, but introductory GR texts tend to cover it
as they go, so it's not really a problem. But they seem to assume
you already know the algebra cold.
About Units and Conventions Used on This Website
Throughout this website, I use the convention that C = 1, and hence
multiplication by C can be ignored. If time is measured in
seconds, then lengths are measured in light-seconds; if time is
measured in years, then distances are measured in light-years.
This simplifies a number of formulas considerably, though at some
occasional cost in clarity.
Except as noted, the Lorentz metric is assumed to be diag(-1,1,1,1).
About Me, and Contact Info
I'm a professional programmer with a long-time interest in math and
physics. I finally decided I wanted to understand something about
general relativity. So I blew a bunch of money on text books, and
since then I've spent lots of my free time studying (or arguing with
various people on sci.physics.relativity).
If you want to get in touch for any reason, please email me.
About Errors
The derivations and proofs on this site are my own. Though I have
tried to be careful, the conclusions here have not, for the most part,
been checked against published books or articles, so it's quite
possible that there are errors either in the reasoning or in the
conclusions. If you happen to run across anything you think is
incorrect, please let me know.
About the Website: Technical Details
Most of the pages on this site were authored using Mozilla (which was
capable of
producing far more sophisticated websites than anything I ever
asked it to do -- the simple site design and primitive formatting are
by choice, not by necessity). Since Mozilla got canned, recent
pages have been authored with a mix of Kompozer (a variant on NVU) and
Seamonkey, depending on whose bugs I find the most annoying on any
particular day. The illustrations were done with
Gimp. Most of the equations were edited with OpenOffice, but
recently I've gotten sick of the never-fixed bugs and limitations in OO
Math and have switched to LaTex (which has a completely different set
of problems). Graphs were
either drawn with splines in Gimp (when the curves were not critical)
or were produced by Gnuplot. The inline
Greek text uses a mix of pictures and HTML Unicode characters, which
may be unreadable in some browsers. Links and image dimensions
are checked with home-brew Perl scripts before uploading, and most
pages have been validated using the W3C validator.
If you have problems with anything on the site
please email me. The pages are served by Apache running on a
Linux box, on space owned by the good folks at ServerSnap.com.
Except for photographs of Einstein, all text,
images,
and computer code on this site, unless otherwise
noted on the individual pages, are
copyright © 2004-2006 by Stephen A. Lawrence. If you copy
anything from this site at least have the good grace to send me email
telling me about it. (In any case my company probably is the
legal owner, since like most of us I signed away my rights when I took
a job. Whatever.)
It's hard for me to imagine how anyone who studies the general
theory of relativity could fail to conclude that Einstein, Hilbert, and
Riemann were brilliant. Einstein, obviously, also had a sense of
humor.
Page last updated 11/16/06
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