20 November 2021 | New Scientist | 41W
E LIVE in the best of all possible
worlds.” So insists Professor Pangloss
against all evidence to the contrary
in the 1759 satire Candide, anyway. The writer
Voltaire intended the character to lampoon
certain theologically tinged scientific thinkers
of the day, who insisted that things couldn’t
be bettered because a beneficent deity would
hardly have willed them otherwise.
Gods and their intelligent designs are less
in the mainstream of scientific thought now,
yet similar ideas about an optimal universe
still trickle through cosmology. That is
principally down to some mysterious numbers
that determine its workings. Tot them all up
in the standard models of particle physics
and cosmology, and you end up with aboutWhy is the universe
just right?
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some of the worst atrocities in human
history, including wars of aggression
and genocide. The Boston Marathon
bomber apparently thought that
radical Islam was a good enough
cause to maim and kill for.
We don’t come fitted with
categories of people that are targets
of our empathy or cruelty, says
Steven Pinker at Harvard University,
author of The Better Angels of Our
Nature: Why violence has declined.
“Whether we’re good or evil depends
on what side of the sympathy
boundary a particular individual
is found,” he says. That largely
depends on whether we see them
as part of our “tribe” at any given
point. If we don’t, we can treat others
exploitatively or instrumentally,
says Pinker. “We can keep slaves,
we can engage in ethnic cleansing,
we treat people like vermin.”
Even members of our in-group
cannot count on our good intentions
all the time. Our sense of justice is
often indistinguishable from our
sense of revenge, so we can be cruel
when we think a person “deserves” it,
says Pinker. A desire for dominance
can lead us to disadvantage those we
see as standing in our way, he says.
But humans also have the capacity
for self-control and, perhaps uniquely,
self-reflection, which has allowed
us to suppress or moderate some
of our baser evolutionary impulses.
Innovations such as the rule of law,
courts and the police go some away
to reduce our power, or our incentive,
to disadvantage others for personal
gain. The continuity and stability
this provides to our societies is one
reason why, contrary to popular
belief, evidence suggests evil is on
the decline, says Pinker – and means
our good need not always be interred
with our bones. Graham Lawton
30 constants of nature – numbers like the
strengths of the fundamental forces and the
masses of elementary particles that our
theories can’t explain, but are just “there”.
Change many of these constants, and
nothing happens. “But with others, it’s drastic,
not to say lethal,” says cosmologist Paul Davies
at Arizona State University. Alter the relative
strengths of gravity and electromagnetism just
a little, say, and stars and galaxies can’t form.
Flip the tiny difference in the proton and
neutron’s masses to make the proton heavier,
and you don’t even get stable atoms.
“Changing these numbers would probably
preclude any life in the universe,” says Davies.
It isn’t a big leap to say it looks like the knobs
have been twiddled – as if the universe were
somehow fine-tuned for our existence.
Stuff and nonsense, says Carlo Rovelli at
Aix-Marseille University in France. “It is sad
that even good scientists fall in this trap,” he
says. “The universe is not ‘just right’, it is what it
is.” For him, to say the cosmos is fine-tuned is a
failure of imagination coming from no one
really having the slightest idea how the
universe would be if its vital parameters were
any different. “It might be perhaps far more
varied and interesting and with all sorts of
strange, complex entities asking silly questions
about how very, very just-right their universe
is,” says Rovelli.
Back in 2008, astronomer Fred Adams at the
University of Michigan did some knob-
twiddling maths to back up this assertion. He
showed, for example, that if the strong nuclear
force were just a little stronger, stars could
synthesise carbon more efficiently, creating a
wider time window for life to evolve. On that
reading, our “fine-tuned” cosmos is a botch job.
For many cosmologists today, to think the
universe is in some way special is to make a
mistake that has long plagued human thought:
to think we are special. “Every scientific
development in cosmology, starting from
Copernicus onward, has shown us that we are
not,” says Priya Natarajan at Yale University.
To extend that thinking to the wider cosmos
is, in part, a balance-of-probabilities hunch.
“You have to decide if the origin of the universe
is a natural, or a supernatural, event,” says
Davies. “If it is a natural event, you wouldn’t
expect it to happen just once.”
Such thinking is increasingly also an
end point of many scientifically grounded
hypotheses. One such is cosmic inflation,
a flash of faster-than-light-speed expansion >