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@ U S T . H K
It is one of the greatest unsolved
mysteries for humanity: what
the beginning of our universe
looked like. Now research by
Prof Yi Wang, an expert in
cosmic perturbation theory, and
his international collaborators,
have unveiled a new prediction that
provides fellow cosmologists globally
with the most robust tool yet to plot
what happened in the primordial
moment of the cosmos.
Cosmic inflation is the leading
paradigm of the primordial universe,
in which the universe expanded
exponentially. However, alternative
scenarios with slowly expanding, slowly
contracting, or fast contracting universes
may also explain what cosmologists have observed. The
problem is that the current way of observing the relics of
the primordial universe is like stacking all the frames of a
movie together. It is unknown which frame is earlier or later,
or the speed that the “movie” is playing.
Working together with long-time collaborator Dr Xingang
Chen, of the Harvard-Smithsonian Center for Astrophysics, and
Dr Mohammad Hossein Namjoo, now at the Massachusetts
Institute of Technology, the team identified a model-
independent way of sequencing what happened in that
initial moment, by using quantum fluctuations of heavy
particles as a “clock”. This clock marks the time of each frame
of the “movie”. Thus, it becomes possible to put the frames
PROF YI WANG
Assistant Professor
of Physics
If I dare only to do
the research where
I am sure there is
some outcome,
I cannot do the
research where
there could be
a great outcome
TRACING THE INITIAL MOMENT
OF THE UNIVERSE
in the right order and “play” it at the right speed,
to find out what happened at the primordial moment
of our universe. Their 2016 paper, “Quantum
Primordial Standard Clocks”, published in the
Journal of Cosmology and Astroparticle Physics
,
attracted global scientific and popular attention.
“Quantum mechanics implies that every object
has an internal frequency as a clock. We applied
this simple principle to the particles in the
primordial universe,” Prof Wang explained.
Prof Wang, a Stephen Hawking Advanced Fellow
at the University of Cambridge before joining
HKUST, looks forward to the moment that
experimental physicists can use the clock to confirm
empirically the evolution of the primordial
universe. This will help in addressing the
ultimate question: where we come from.
How does such research relate to
society? “Science and technology are
how modern society differs from ancient
times. Fundamental science is of
particular importance because it is the root
of technology,” he said. It is also essential
that this curiosity-driven excitement and
motivation to explore frontier knowledge is transmitted to
the next generation. “Even primary students can be inspired
by the origin of the universe,” he noted.
Prof Wang’s research findings have
appeared in
Journal of Cosmology and
Astroparticle Physics
and
Journal of High
Energy Physics,
among others.
