PDA

View Full Version : Variable Fundamental Constants?

Light Eye
04-11-2005, 02:16 AM
dear friends,

interesting.

http://www.ast.cam.ac.uk/~mim/res.html#team

love and light.

david

variable fundamental constants?

i am a post-doctoral research associate at the institute of astronomy,
university of cambridge. a major part of my work concerns the question "do the
constants of nature vary?". for the past 5 years i have been working with john
webb and victor flambaum on a search for possible variations in the fundamental
constants of nature, particularly the fine structure constant, usually denoted
by the greek letter alpha.

the alpha project has received sustained media publicity and i have tried to
keep a scrap book of some of the major media releases here.

the following is an explanation of my research in layman's terms. see also chris
churchill's fine structure constant page for more non-technical information. a
slightly more technical overview article has recently been published in physics
world magazine. if you want a more technical explanation then i suggest you read
some of my recent publications.

the basics
here are some links explaining the basics of fundamental constants with
particular emphasis on alpha.

what is a fundamental constant?: @ nist
what is the fine structure constant?: @ nist, @ physlink
how are the constants measured?: @ physics today

put briefly, a fundamental constant is a number that is central to a given
theory - that is, to calculate/predict the results of an experiment, you need to
know that number. but you can't use known theories to calculate that number - it
must be measured in an experiment. in essence, these numbers are fundamental
because we have no idea where they come from! and since no-one knows how to
calculate their values, and because we do find the same value with different
experiments conducted at different times/places, we assume that these numbers
are, in fact, constants. the experiments we conduct tend to be limited to
laboratories on the earth during the last 100 years or so. but what if the
constants are/were different in different places in the universe or at different
epochs in cosmic history? an experiment should test the constancy of the
constants in these extreme cases.

our experiment picks on one very well known constant: the fine structure
constant, alpha. this constant is the central parameter in electromagnetism -
the theory of how light and matter interact. alpha is a combination of other
constants that you might be more familiar with: alpha = e2/hc where c is the
speed of light, e is the charge of an electron and h is planck's constant. thus,
alpha is important for a relativistic (i.e. c) quantum mechanical (i.e. h)
theory of electromagnetism (i.e. e). but alpha is, in some sense, more
fundamental the these other constants (see aside - is it c or e that varies?).
alpha is known to exquisite precision from laboratory measurements:

1/alpha = 137.03599958

[non-text portions of this message have been removed]