- Wilczek, Frank.
The Lightness of Being.
New York: Basic Books, 2008.
ISBN 978-0-465-00321-1.
-
For much of its history as a science, physics has been about mass and
how it behaves in response to various forces, but until very recently
physics had little to say about the origin of mass: it was
simply a given. Some Greek natural philosophers explained it as being
made up of identical atoms, but then just assumed that the atoms
somehow had their own intrinsic mass. Newton endowed all matter with
mass, but considered its origin beyond the scope of observation and
experiment and thus outside the purview of science. As the structure
of the atom was patiently worked out in the twentieth century, it
became clear that the overwhelming majority of the mass of atoms
resides in a nucleus which makes up a minuscule fraction of its
volume, later that the nucleus is composed of protons and neutrons,
and still later that those particles were made up of quarks and
gluons, but still physicists were left with no explanation for why
these particles had the masses they did or, for that matter, any mass
at all.
In this compelling book, Nobel Physics laureate and extraordinarily
gifted writer Frank Wilczek describes how one of the greatest
intellectual edifices ever created by the human mind: the
drably named “standard model” of particle physics,
combined with what is almost certainly the largest scientific
computation ever performed to date (teraflop massively parallel
computers running for several months on a single problem),
has finally produced a highly plausible explanation for the
origin of the mass of normal matter (ourselves and everything
we have observed in the universe), or at least about 95%
of it—these matters, and matter itself, always seems to
have some more complexity to tease out.
And what's the answer? Well, the origin of mass is the
vacuum, and its interaction with fields which fill
all of the space in the universe. The quantum vacuum is a
highly dynamic medium, seething with fluctuations and
ephemeral virtual particles which come and go in instants
which make even the speed of present-day computers look
like geological time. The interaction of this vacuum with
massless quarks produces, through processes explained
so lucidly here, around 95% of the mass of the nucleus
of atoms, and hence what you see when stepping on the bathroom
scale. Hey, if you aren't happy with that number, just remember
that 95% of it is just due to the boiling of the quantum
vacuum. Or, you could go on a
diet.
This spectacular success of the standard model, along with its
record over the last three decades in withstanding every
experimental test to which it has been put, inspires confidence
that, as far as it goes, it's on the right track. But just
as the standard model was consolidating this triumph, astronomers
produced powerful evidence that everything it explains: atoms,
ourselves, planets, stars, and galaxies—everything we
observe and the basis of all sciences from antiquity
to the present—makes up less than 5% of the total mass
of the universe. This discovery, and the conundrum of how the
standard model can be reconciled with the equally-tested
yet entirely mathematically incompatible theory of
gravitation, general relativity, leads the author into
speculation on what may lie ahead, how what we presently know (or
think we know) may be a piece in a larger puzzle, and how experimental
tests expected within the next decade may provide clues and open the
door to these larger theories. All such speculation is clearly
labeled, but it is proffered in keeping with what he calls the Jesuit
Credo, “It is more blessed to ask forgiveness than
permission.”
This is a book for the intelligent layman, and a superb
twenty page glossary is provided for terms used in the text
with which the reader may be unfamiliar. In fact, the glossary
is worth reading in its own right, as it expands on many
subjects and provides technical details absent in the
main text. The end notes are also excellent and shouldn't
be missed. One of the best things about this book, in my
estimation, is what is missing from it. Unlike so
many physicists writing for a popular audience, Wilczek feels
no need whatsoever to recap the foundations of twentieth
century science. He assumes, and I believe wisely, that
somebody who picks up a book on the origin of mass by a
Nobel Prize winner probably already knows the basics of
special relativity and quantum theory and doesn't need to
endure a hundred pages recounting them for the five hundredth
time before getting to the interesting stuff. For the reader
who has wandered in without this background knowledge, the
glossary will help, and also direct the reader to
introductory popular books and texts on the various topics.
March 2009 