Doctor in philosophy and moral sciences (VUB).
Title of my dissertation: Top-Down Cosmology and Model-Dependent Realism. A Philosophical Study of the Cosmology of Stephen Hawking and Thomas Hertog, Uitgeverij VUBPRESS Brussels University Press, 2021.
dr.. Alexander François van Biezen
Supervisor: prof. dr. Gustaaf C. Cornelis.
Popular-scientific abstract
Within the domain of history and philosophy of cosmology, I
investigated the cosmological work of Stephen Hawking — the famous British
scientist in a wheelchair — and Thomas Hertog — his Flemish disciple — between
2006 and 2018. In 2006, Hawking and Hertog put forward a new framework called top-down
cosmology. This approach starts from the present (“at the top”), with the
properties of the universe as we can observe it today, and works its way back
to the past (“down to the bottom”). This framework views the origin of the universe
as all possible histories layered on top of each other. The universe did not
have a single, unique beginning. Instead, it began in about every possible way.
What makes top-down cosmology stand out,
compared to many other competing approaches, is Hawking’s attempt to scaffold
his cosmological work by means of his philosophy of model-dependent realism.
Scientific realism holds that our best scientific theories are approximately
true and that the unobservable objects they refer to really exist. Hawking
claims it is meaningless to ask whether a theory is real, only whether
it agrees with observation. When two competing, even mutually incompatible,
theories agree with observation, it is impossible to say one is more real than
the other. From a philosophical point of view, model-dependent realism
is seriously flawed, because it is insufficiently worked out with regard to
modern model theory and self-refuting as a philosophical claim (as Hawking
dismissed philosophy altogether). However, from a cosmological point of view,
it gave Hawking and Hertog a practically unconstrained liberty to play with
concepts and tools of different branches of physics needed to construct their
cosmological models.
To find out
whether model-dependent realism is just a brazen and failed attempt at
philosophising or a brilliant strategic move with solving a fundamental
cosmological problem in mind, I examined the relationship between top-down
cosmology and model-dependent realism from different angles. I have come to the
conclusion that, when viewed from a broader perspective, Hawking’s and Hertog’s
approach in cosmology is indicative for a gradually changing attitude within
the scientific community of fundamental physics and cosmology about what counts
as “the scientific method”. Traditionally, a theory was regarded as scientific
when it made predictions which could be falsified through experiment or
observation. However, recent decades gave rise to physical theories like string
theory whose predictions lie way beyond the reach of what is currently
technically possible. Top-down cosmology fits in with this growing trend of a
more lenient view towards falsifiability of a theory and a stronger focus on
the conceptual characteristics of a theory (like simplicity, elegance, range,
internal and external consistency) to evaluate its viability.
