Let’s say you’ve settled in with a cup of
coffee and your go-to read. As you flip through the pages, you take in the
artwork on the cover, the feel of your fingers on the book’s smooth sleeve, and
that distinct scent that only books have. The book presents itself to you in a
variety of forms. But you also anticipate that the book
exists apart from its outward manifestations. When you set the book down on the
coffee table and head to the kitchen or out the door to go to work, you want it
to retain the same look, feel, and fragrance as when you first picked it up.
Expecting objects to have their own
independent existence – independent of us, and any other objects – is a
deep-seated assumption we make about the world. This assumption has its origin
in the scientific revolution of the 17th century and is part of what we call
the mechanistic worldview. According to this view, the world is like a giant
clockwork machine whose parts are governed by set laws of motion. This view of the world is responsible for
much of our scientific advancement since the 17th century. But as Italian
physicist Carlo Rovelli argues in his new book Helgoland, quantum theory – the
physical theory that describes the universe at the smallest scales – almost
certainly shows this worldview to be false. Instead, Rovelli argues we should
adopt a “relational” worldview.
What does it mean to be relational?
The English physicist Isaac Newton and his
German colleague Gottfried Leibniz had fundamental philosophical differences
about the nature of space and time during the scientific revolution. According to Newton, space and time serve
as a “container” for everything in the cosmos. If all the planets,
stars, and galaxies in the universe were suddenly erased, we would be left with
nothing but time and space. The “absolute” perspective on space and
time looks like this.
However, according to Leibniz, space and
time are nothing more than the aggregate of all the distances and times between
everything in the universe. Space and time would vanish along with the cosmos’
contents. That’s the “relational” perspective on space and time,
which sees them as nothing more than the connections between things and
occurrences. Einstein drew significant motivation for his development of general
relativity from the relational perspective of space and time.
To better grasp quantum mechanics, Rovelli
employs this concept. He argues that a photon, electron, or any other
fundamental particle in quantum theory is nothing more than the attributes it
displays in relation to other objects. The position, momentum, and energy of a
quantum item, among other things, can be determined experimentally. They all
contribute to an object’s state. Rovelli’s relational interpretation holds
that these traits are all that an object has; there is no separate substance
that “has” these qualities.
So how does this help us understand quantum
theory?
Take Schrödinger’s cat, a famous quantum
problem. Using a quantum process (such as the decay of a radioactive atom), we
seal a cat inside a box with a lethal agent (such as a vial of poison gas) and
then close the lid. Quantum mechanics involves a random
process. Although it cannot be predicted, the probabilities of atomic decay
over a certain time frame can be described. The cat’s life or death is also a
random event since decay will force the bottle of toxic gas to be opened,
killing the cat.
Until the box is opened, and the system is
observed, the cat is neither dead nor alive, according to standard quantum
theory. What it would be like for the cat if it were neither dead nor living
remains a mystery. However, in the relational view, the status
of a system is always contextualized with respect to other systems. The outcome
of the quantum process in the box may be uncertain for us, but the cat may
perceive it quite differently. Thus, it stands to reason that the cat is
neither dead nor living for humans while being unquestionably dead or alive
for the cat. For humans, one thing is true, and for the cat, something else entirely.
When we open the box, the cat’s condition becomes clear, but for the cat, it
was never uncertain.
There is no “God’s eye” or
all-encompassing perspective on things in the relational interpretation.
What does this tell us about reality?
Rovelli thinks that we should pay attention
to these warnings since the world we live in is fundamentally quantum. The
properties of certain things, like your beloved book, may only exist in
connection to other things, like you. Fortunately, that also applies to
everything else in the room, including the coffee table. This means that your
beloved book will look the same when you put it down to go to work. Still, it
represents a radical revision of our understanding of the world.
For proponents of this theory, the universe
is a never-ending game of quantum mirrors in which nothing exists in isolation
from everything else. Furthermore, it’s possible that this web is not supported
by any independent “metaphysical” material.