On the Equality of All Things: Physics and Philosophy
by Carlo Rovelli (Translator) Simon Carnell
Allen Lane. 192 pages. £20. ISBN: 978-0-241-73370-7
Reviewed by Tony Roberts
‘Reality is often very different than it seems’, wrote Carlo Rovelli, an Italian
theoretical physicist and a master populariser of the modern revolution in
science. He has written a number of short books exploring the subject, packed
with ideas, many of which have breathtakingly counter-intuitive observations of
the world we live in, the everyday Newtonian and the quantum. Seven Brief
Lessons in Physics (2015) invoked Einstein’s general theory of relativity
and quantum mechanics. The Order of Time (2018) explored what ‘gives rise
to the [idea of] time that we are accustomed to’.
In his
new book, On the Equality of All Things, Rovelli offers an update on ‘the
conceptual and philosophical implications of the current scientific revolution
in thinking’ about our world, a world in which, ‘Everything is process;
everything is on the move (‘Even a stone never stays the same: it is a
succession of tiny events’).
What he
proposes is ‘the relational interpretation of quantum mechanics,’ though not as
the last word—since, to use his own formulation, everything is ‘approximate and
perspectival’— but as a ‘fertile’ field of consideration, which counters our
frequently ‘overly realist prejudices’. By ‘relational’ he means that, ‘Things
all exist equally, in relation to others, each in its own way —a way that
evolves as we learn.’ And that includes everything. There is no ‘absolute,
ultimate reality’ science can reveal. Its task is rather to continue to achieve
a greater understanding of the world.’
The
author acknowledges at the outset that his audience is wide and includes both
the interested layman (like myself) and the scientifically educated. Most
readers will appreciate the clarity of the prose, though they might well face
difficulties understanding or absorbing certain explanations.
To the physicists and scientifically literate, Rovelli has helpfully
addressed many detailed footnotes. For the rest of us, repetition of key points
in the book serves as reinforcement of often deceptively simple-seeming ideas.
And so
the book gives us six bracing lessons, one per chapter: on quanta, knowledge,
space and time, the flow of time, nature, the absence of foundations and, in an
‘Afterward’, how science works.
With
Lesson 1, ‘The Relational Structure of Reality’, his starting point is our need
to recognise that our counter-intuitive ideas about life and the world are often
the product of the smallness of our experience on this small planet Earth.
Rovelli asks us to recognise that we live by accumulated assumptions which are
not all accurate: ‘The mistake is to believe that the concepts we have are
necessarily adequate for understanding reality.’ These need to ‘evolve’. For
instance, many people assume that the universe behaves as earth does. Yet, for
example, the universe has no recognition of the flow of time.
Rovelli
writes, ‘Before the discovery of quanta, we assumed that we could think about
the world as made up of objects with intrinsic properties, each independent from
everything else and each having a definite value at any given moment… Quantum
phenomena are not compatible with this idea.’ Which is to say that, ‘The
properties of an object are relations between objects: they exist in
physical interactions.’
So
everything has a context and overlapping perspectives exist on everything. There
is no here and now, ‘no “where” or “when”, except in a relative sense.’ There
can be no ‘ultimate reference point’, no final authority, no absolute
measure for anything. We cannot take a perspective outside language, outside our
reality, to confirm things.
Lesson
2, ‘From Inside the Circle’, concerns certainty and knowledge. Certainty then
must be approximate, a matter of degree. And knowledge itself is not
disembodied, just as the language in which we express it is not (Apologies to
Elizabeth Bishop, who memorably wrote: ‘It is like what we imagine knowledge to
be: / dark, salt, clear, moving, utterly free’).
That
is, there is always a speaker, a writer, a language of expression —a
perspective. Rovelli is here highlighting ‘the similarity between the relational
structure of the physical nature of knowledge, and the relational structure of
quantum phenomena’ [i.e. subatomic particle behaviour].
For
Lesson 3, ‘Spacetime is a Quantum Process’, I had to do some homework. The
Standard Model of particle physics, developed in the later twentieth century,
sees matter and energy as comprised of the forces of gravity and
electromagnetism, which can be seen in the everyday world, and of weak
interaction and strong interaction, which produce forces at subatomic level
(think nuclear interactions in atoms). Gravity is not included in the Standard
Model; it is said to be incompatible. However, Rovelli and others are engaged in
research into a quantum theory of gravity that comes from Einstein’s work on
general relativity and ties the two together. To Rovelli, Einstein’s ‘Spacetime
is a quantum gravitational process.’ Such
research is seen as part of the search for a unified theory of the universe.
To the
author, this century’s physics points: ‘To this understanding of the world as
made up of processes, mirrored into other processes, from which solid or fluid
matter, space, time and everyday experience emerge.’ Or, as he puts it in a more
relaxed fashion, ‘Quantum theory and general relativity slip naturally into each
other’s arms. They seem made for each other.’
‘Inhabiting the Flow of Time’, Lesson 4, takes up the notion of ‘the arrow of
time’, missing from both quantum gravity and Newtonian mechanics. To Rovelli
many of us fail to understand time because we think of it as ‘absolute and
universal, underlying everything and prior to everything else’. Again —and again
counter-intuitively — this is because our image of the world is limited by our
experience of it.
We are,
of course, time-orientated because we are mortal (i.e. ‘dissipative phenomena’
—like everything else): ‘Our confusion about time lies in our evolutionary
development as organisms that need to remember, predict and plan.’ As he neatly
puts it: ‘It is our thinking that runs forward, not time.’ Also, we have built
systems which constantly remind us: ‘The confusion lies in the naïve assumption
that all features of our rich experiential time — which largely depends on the
structure we are —are shared by any mechanical process. As if a clock could
remember the past and decide its next tick.’
More
difficult to inwardly digest is his point that, ‘The key to understanding the
flow of time is to grasp the fact that [such] phenomena [as notions of past and
future, cause and effect] are not manifestations of the flow of time:
they are themselves what we mean when talk about the flow of time.’
Similarly difficult to assimilate is the following: ‘The intuition of duration
is generated in us by our memories and our anticipations.’
Lesson
5, ‘What Exists?’ argues that everything does: a tree, a cloud, a photon, a
thought, a hope: ‘In each case, we use appropriate criteria of reality, slightly
different in different cases. This is the equality of all things.’ In this view,
everything is physical and nothing breaks physical laws. Furthermore,
there are innumerable perspectives on what we call reality and no reality that
can exist beyond and independent of the physical world. This includes God and
absolute morality. Rovelli is quick to distinguish between ‘relative’ and
‘arbitrary’ when it comes to morality. His analogy is with the moon, which is
relative to the earth but not arbitrary in its motion. So morality remains in
the orbit of societal values of its time, relative but not arbitrary, perhaps
changing as values do. Reality, he concludes disarmingly, ‘is nothing more than
the name we give to the content of everything we know about it’.
‘Without Certainty or Foundations’, Lesson 6, reminds us that ‘Any physical description of the world is always a partial and perspectival description.’ So far in On the Equality of All Things I have got along passably well with understanding Rovelli’s ideas (I hope), but at this point I stumble over an earlier allegiance. He gives a famous anecdote of Zhuangzi and Huizi walking across a bridge. The first observes that the fish are happy; the second questions how he can know that, not being a fish. Rovelli reads Huizi’s position as a claim ‘that happiness is a subjective matter, and as such is not visible from the outside’.
He goes
on to cite Thomas Nagel’s renowned article ‘What Is It Like to Be A Bat?’ as
another example based on the false idea that ‘subjective experience is hidden’.
I have hitherto subscribed to Nagel’s view in his bat essay. Now I wonder if
physicalism, Rovelli’s position, does reveal to us that subjectivity
is accessible. Since science is objectively third-person in its descriptions how
can it explain our sense of what Henry James referred to as ‘felt life’, the
palpable sense we have of experiences, the ‘what it is like’? Nagel would say,
in effect, that Rovelli’s position is incomplete without it.
All
this ties in with Rovelli’s view of what David Chalmer’s described as the ‘hard
‘problem of consciousness, which he goes on to discount. This other famous
distinction in the philosophy of mind distinguished between the ‘easy’ problem
of consciousness (brain procedures) and the ‘hard’ one which is ‘what it is
like’ to be conscious. The hard problem is a non-problem to Rovelli because ‘it
is just the answer we give to what happens’ and comes ‘from forgetting that the
subject is itself part of nature’. He is, in other words, against the idea of
duality (given his belief in the equality of all things). Instead he maintains
that ‘Mental processes are physical processes.’ The brain and the mind are not
two separate things. All is circularity.
The
last lesson, Lesson 6, is ‘How Does Science Work?’
Here we are assured first of some common-sense views: ‘that language is
ambiguous, for example, and can trip us up; that concepts are expressed in
metaphors and analogies that are always relational, since everything —as the
author says again—is relational.
He
reiterates the view that the difference between scientific knowledge and other
forms of knowledge ‘is a difference of degree, not of nature’. Science’s world
is our world ‘with just a few more details’. He uses a table as an example. From
one viewpoint a table is a table, from another glucose molecules, etc. In other
words, he argues, the world cannot be exactly as we see it because we see it in
many different ways from so many different perspectives.
Rovelli
makes the interesting point that science understanding is cumulative and that
misrepresentation of Thomas Kuhn’s work on paradigms has led us to think each
hypothesis destroys its predecessor in the history of science. There are no
revolutionary moments in this sense. For instance Copernicus did not discard
Ptolemy, but built on his work. Newton was not deemed wrong, but updated by
Einstein’s theory, which incorporated it.
On the
Equality of All Things
is understandably more a physicist’s book, than a philosopher’s, despite its
subtitle. Perhaps this is because, as Rovelli writes early on, ‘even that part
of philosophy which is attentive to science seems to me to struggle to come
fully to terms with the tumultuous scientific revolution that is currently
underway’. A number of philosophers are called forth in the book, but some for
correction —not so Wittgenstein (and Kierkegaard, who influenced Niels Bohr).
I liked
John Banville’s description of this book in the Irish Times, as ‘a
marvellous, insouciant and liberating book’. There is always something
cheerfully ‘insouciant’ about Rovelli’s writing. This includes his message: ‘We
are part of the world that we know and describe. We are not strangers in
reality. We are at home there.’
Although we may not be ‘strangers in reality’, we may be forgiven for feeling
that reality has its strangenesses.
On the
Equality of All Things
is a very stimulating —if occasionally bewildering— adventure in thought.