Scientists make waves with black hole research

From left to right are: Dr. Silke Weinfurtner, Antonin
Coutant, Theo Torres, and Sam Patrick. Credit: The University
of Nottingham

Scientists at the University of Nottingham have made a
significant leap forward in understanding the workings of one
of the mysteries of the universe. They have successfully
simulated the conditions around black holes using a specially
designed water bath.

Their findings shed new light on the physics of with the first laboratory evidence of
the phenomenon known as the superradiance, achieved using water
and a generator to create waves.

The research – Rotational superradiant scattering in a vortex
flow – has been published in Nature Physics. It was
undertaken by a team in the Quantum Gravity Laboratory in the
School of Physics and Astronomy.

The work was led by Silke Weinfurtner from the School of
Mathematical Sciences. In collaboration with an
interdisciplinary team she designed and built the black hole
‘bath’ and measurement system to simulate black hole

Dr Weinfurtner said: “This research has been particularly
exciting to work on as it has bought together the expertise of
physicists, engineers and technicians to achieve our common aim
of simulating the conditions of a black hole and proving that
superadiance exists. We believe our results will motivate
further research on the observation of superradiance in

What is superradiance?

The Nottingham experiment was based on the theory that an area
immediately outside the event horizon of a rotating black hole
– a black hole’s gravitational point of no return – will be
dragged round by the rotation and any wave that enters this
region, but does not stray past the event horizon, should be
deflected and come out with more energy than it carried on the
way in – an effect known as superradiance.

Superadiance – the extraction of energy from a rotating black
hole – is also known as the Penrose Mechanism and is a
precursor of Hawking Radiation – a quantum version of
black-hole superradiance.

What’s in the Black Hole Lab?

Dr Weinfurtner said: “Some of the bizzare black hole phenomena
are hard, if not, impossible to study directly. This means
there are very limited experimental possibilities. So this
research is quite an achievement.”

The ‘flume’, is specially designed 3m long, 1.5m wide and 50cm
deep bath with a hole in the centre. Water is pumped in a
closed circuit to establish a rotating draining flow. Once at
the desired depth waves were generated at varied frequenices
until the supperadiant scattering effect is created and
recorded using a specially designed 3D air fluid interface

Tiny dots of white paper punched out by a specially adapted
sewing machine were used to measure the flow field – the speed
of the fluid flow around the analogue black hole.

It all started from humble beginnings

This research has been many years in the making. The initial
idea for creating a supperradiant effect with water started
with a bucket and bidet. Dr Weinfurtner said: “This research
has grown from humble beginnings. I had the initial idea for a
water based experiment when I was at the International School
for Advanced Studies (SISSA) in Italy and I set up an
experiment with a bucket and a bidet. However, when it caused a
flood I was quickly found a lab to work in!

After her postdoc, Dr Weinfurtner went on to work with Bill
Unruh, the Canadian born physicist who also has a made seminal
contributions to our understanding of gravity, black holes,
cosmology, quantum fields in curved spaces, and the foundations
of quantum mechanics, including the discovery of the Unruh

Her move to the University of Nottingham accelerated her
research as she was able to set up her own research group with
support from the machine shop in the School of Physics and

Explore further:

Water circling drain experiments offer insight into black

More information: Theo Torres et al, Rotational
superradiant scattering in a vortex flow, Nature Physics
(2017). DOI:

Journal reference: Nature

Provided by: University
of Nottingham