28 March 2020 | New Scientist | 31Book
The World According
to Physics
Jim Al-Khalili
Princeton University Press
ONE afternoon in 2016, New
Scientist consultant Stuart Clark
and I barricaded ourselves in a
room, armed with flip charts and
pens, in a bid to work out what
fundamental physics looked like.
This turned out to be a confusion of
lines and arrows – dotted, looping,
scribbled out, realigned – between
boxes adorned with “E = mc^2 ”,
“uncertainty principle (?)”, “quantum
field theory” and “cosmic inflation!”.
The finished product was more
coherent. We were proud of it when
it appeared in New Scientist – even
if we had somehow forgotten about
thermodynamics. We could have
done with the clear mind of a Jim
Al-Khalili. Loyalty doesn’t allow me
to admit he has made a better job of
what we attempted, but his new
book is really rather good.
Al-Khalili, a nuclear physicist
at the University of Surrey, UK,
is well known for BBC Radio 4’s
The Life Scientific, in which he
interviews leading scientists.
He describes The World According
to Physics as an “ode to physics”,
the subject he fell in love with
as a teenager. Like Carlo Rovelli’s
bestseller Seven Brief Lessons on
Physics, it is short. But in extending
Rovelli’s 96 pages to 300-odd, he
offers a thorough overview of what
physics says about reality and the
problems created in so doing.
It is an interesting time for such
a survey. The early 20th-century
innovations of Einstein’s relativity
and quantum mechanics, and
experimental and observational
advances on scales from the very
small to the vast expanse of the
cosmos, more or less overturned
everything we thought we knew.
These innovations allowed the
development of two “standard
models” – of particle physics and
of cosmology – that, with the laws
of thermodynamics, could be seen
as telling us all we need to know.
Yet as Al-Khalili observes, we are
further away from the end of physicsthan we thought 30 years ago.
In part, that is because relativity
and quantum mechanics provide us
with very different, contradictory,
pictures of such fundamentals as
space and time. In Einstein’s picture,
these meld into one smooth fabric,
space-time; in quantum theory,
they remain strangely apart.
Once again, that is to ignore
thermodynamics, which provides
a third picture of the flowing time
we experience, caused, as Al-Khalili
tells it, by the increase of “useless
energy”, or entropy. Some argue this
connection isn’t so cut and dried.And to square our standard model
of cosmology with observations of
the universe, we had to invent dark
matter and dark energy, which
together make up 95 per cent of
all stuff but which quantum theory
(the directing theory of “stuff”)
can’t explain. Lots still to do, then.
Al-Khalili’s easy turn of phrase
and feel for metaphor give us a
sense of fundamental physics as a
box of delights and woes. His true
metier is quantum physics, where
he is admirably lucid and even-
handed in dealing with the various
interpretations that seek to explain
its picture of a “fuzzy” reality so
at odds with our lived experience.
Here mystery builds on mystery,
culminating in a split. Some say we
shouldn’t concern ourselves with
the workings of the quantum world,
because the picture the theory
delivers squares with experiments
and allows useful technologies to be
built on top of it. Others believe
physics should describe the world,
and tell us why things are as they
are. Al-Khalili is one such, but
because he doesn’t have a pet
theory, he can argue both for
fundamental physics and for the
scientific method – less for offering
enlightenment as a destination than
for a thrilling journey.
Which, I think, was what our pens
and flip charts were about too. ❚Should physics describe
the world and explain why
things are as they are? HA
RALD
RITSC
H/SCIENCE^ PHOTO
LIBRARYAn ode to physics
Explaining the state of the art in physics is a job for one of the UK’s
most popular science communicators, says Richard Webb
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