34 | New Scientist | 15 February 2020don’t, do bacteria?” asks physicist Sean Carroll
at the California Institute of Technology. “I don’t
know, but human beings do. Somewhere along
that continuum it sneaked in.”
Philosophers and theologians have been
poring over that and agency’s relationships to
other thorny concepts, such as consciousness
and free will, for millennia (see “Life, agency
and everything”, page 36). But it is since
humans started to do physics that agency has
taken on particularly puzzling proportions.
The aim of physics is to characterise the
interaction and evolution of reality’s elements
through cast-iron mathematical laws with
predictive power. That mission is far from
complete, but it has been stunningly successful
so far. From Isaac Newton’s laws of motion
and gravitation to Albert Einstein’s relativity
and the enigmatic edifice of quantum theory,
we now have laws explaining everything
from how apples fall to how biological and
chemical processes unfold to the origin and
fate of the universe.
Take an apple’s sudden detachment from
a tree. It is caused by a complex series of
biochemical processes, plus the whims of
wind and weather, all explicable by the laws
of physics. Given enough computational
power, in theory we could trace the chainI
’VE been thinking about getting a puppy.
You know, for a bit of companionship,
something to motivate on grey days
when spirit and flesh are weak.
I even went to a stray dogs’ home, because
that seemed the right thing to do. There was a
lovely one there, with beautiful, mischievous
eyes. She reminded me of a mutt we had when
I was a kid, called Whiskey. I bottled it in the
end, though. Did I really have the time to give
her the love and attention she deserved?
Whims, memories, hopes, judgements,
morals, qualms – all coming together to
influence decisions. It is hard enough for
us to understand how we reach them. For
fundamental physicists, it is a complete
mystery. That is because our decision-making
ability is a not-so-secret superpower to alter
the physical world, changing its evolution
apparently at will – something no physical
law yet devised can explain.
“We act, we decide, we initiate actions,”
says Carlo Rovelli at Aix-Marseille University
in France. “How can we insert this agency into
the general picture of nature?”
Rovelli and others have undertaken to find
out. Their journey has led them into the depths
of the human mind and its relationship with
JUANJO GASULLphysical reality, throwing up surprising
Features Cover story
and profound connections: to the mysteries
of entropy and flowing time, to reality and
consciousness, and to the nature of physical
law itself. Get to grips with what underlies
our everyday acts, and we could be on the
way to a deeper, all-inclusive understanding
of both the cosmos and our place in it.
At its simplest, agency is relatively easy
to define. “It is just the notion that certain
systems in the world have intentional states,
desires to bring stuff about,” says philosopher
Eleanor Knox at King’s College London.
“We’re clearly systems like that.”
The arguments start with what else is too.
“Quantum fields don’t have any agency. Atomsour place in
Physicists are limbering up for their greatest trick
yet – explaining how decision-making beings like
you and me fit into the cosmic order,
says Richard Webb
“ Physics aims
to characterise
everything through
cast-iron laws with
predictive power”
Finding
the universe
>