8 | New Scientist | 10 August 2019
EntomologySUPERGRAVITY is the idea that
launched a thousand theories.
It suggests that the particle
thought to cause gravity ought
to have a partner, and from this
concept came a possible way
to solve some of the biggest
mysteries in physics, from
unifying gravity with quantum
mechanics to explaining
the effects of dark matter.
The three people who
formulated supergravity –
Sergio Ferrara, Daniel Z.
Freedman and Peter van
Nieuwenhuizen – have now
been awarded the $3 million
Special Breakthrough Prize
in Fundamental Physics in
recognition of their work.
New Scientist spoke with
van Nieuwenhuizen.What is supergravity?
Supergravity is a combination
of general relativity with the
idea of supersymmetry, which
is a symmetry between the
two kinds of particles we see in
nature, bosons and fermions.
In supersymmetry, every boson
should have a partner particle
that is a fermion and every
fermion should have a partner
boson. General relativity
predicts a particle called the
graviton, which is a boson,
and supergravity adds another
particle called the gravitino, a
fermion, to be its superpartner.
The gravitino has quantum
properties that general
relativity alone doesn’t have.Where does the idea of
supergravity come from?
Supergravity is an extension,
but not a replacement, of
Einstein’s theory of general
relativity. A significant
outstanding problem in
physics has always been to
unify quantum mechanicsand relativity. That happens
in supergravity.What does supergravity have
to do with string theory?
String theory is an extension
of supergravity in which the
elementary particles aren’t
points but little pieces of wire.
Supergravity is the low-energy
limit of string theory, so if you
ever want to do experiments,
you have to go back to the real
world and low energy, and
that’s supergravity. Nowadays,
supergravity and string
theory are the same thing.Are there any other problems
that supergravity could solve?
Some people speculate that
dark matter may consist of the
supersymmetric partners of
the graviton, the gravitino. If
gravitinos can solve this riddle
of dark matter, it would be a
great achievement.No one has found any
supersymmetric partner particles
yet. Does that bother you?
My hope is that there will be
another larger collider in China
and also that the mass of the
supersymmetric particles will
be in the range that the nextcollider is making discoveries.
If we don’t find these particles,
supergravity will survive
as a tool to help with other
calculations in physics and
mathematics, but what is
more important to me is
physical reality. If it isn’t a
theory of physical reality,
I will be very disappointed.Were you excited to find out
that you had won the Special
Breakthrough Prize? Do you have
any plans for the prize money?
When Edward Witten [chair of
the selection committee] called,
I was nervous that he was going
to ask me a hard question about
supergravity that I couldn’t
answer. But instead, he said,
“I am happy to inform you that
you have won the Breakthrough
Prize 2019.” I was speechless.
I haven’t thought much about
what I’m going to do with it yet.
I haven’t had much time. I am
80 years old, I still work, I still
teach graduate courses that
I love, and that is my life. ❚Profile
Peter van Nieuwenhuizen
at Stony Brook University in
New York is a joint winner of the
Special Breakthrough Prize 2019A COMMON species of wasp
appears to be becoming smaller
as a consequence of the ongoing
global rise in temperatures.
Warming-driven shrinkage has
been documented in vertebrates,
such as antelopes and sparrows,
but climate change’s impact
on insect body size is poorly
understood. Carlo Polidori at the
University of Castilla-La Mancha,
Spain, and his colleagues used
many decades of insect samples
at Madrid’s National Museum of
Natural Sciences to see how they
have changed over time.
The team measured the body
size, head width and wing size of
over 200 tree wasp (Dolichovespula
sylvestris) specimens from various
locations on the Iberian peninsula.
Some dated back to 1904.
Polidori and his colleagues
found that the wasps got smaller
over time (Ecological Entomology,
doi. org/c85c). Comparing the data
with Iberian climate records, they
discovered that this decline in size
correlated with rising temperatures.
The team can’t be sure if
climate caused this change, but it
is possible that hotter temperatures
speed up wasps’ early development,
resulting in smaller adults.“Body size shrinking is likely to
have some adverse effects on recent
and future insects,” says Polidori.
“For example, smaller wasps may
be able to hunt only smaller prey
species compared with past wasps.”
Oddly, the wasps’ wings are
shrinking faster than the rest of
their bodies. If changes to the
wing shape aren’t occurring
as well, Polidori suspects that
modern wasps could be less
agile and speedy in flight. ❚Supergravity takes the prize
Interview Peter van NieuwenhuizenJake Buehler“If changes to the wing
shape aren’t occurring as
well, modern wasps could
be less speedy in flight”JOHN GRIFFIN/STONY BROOK UNIVERSITY COMMUNICATIONSNews
One of the discoverers of the concept that led to string theory
discusses his award-winning work with Leah CraneWasps may be
shrinking due to
climate change