THENEWYORKER,OCTOBER11, 2021 25
work in fusion at M.I.T., said. “And we
were sure we were going to be the ones
to solve it all.”
Steven Cowley, the former head of
the U.K. Atomic Energy Authority,
who now heads the Princeton Plasma
Physics Laboratory, recalled his days
as a graduate student at Princeton, in
the nineteen-eighties. “Fusion was all
we thought about, from the time we
woke up in the morning to the last beer
in the basement of the graduate col-
lege,” he said. “I remember when we got
to ten million watts of fusion power
on T.F.T.R.”—Princeton’s fusion device.
“I still have a photo of that moment
outside my office.” It was a tremendous
milestone, but it also, basically, created
enough energy to light up a single bulb
for a day. More needed to be done.
But, by the nineties, oil was cheap
again. Fusion research funding declined.
“We had learned to extract oil and gas
from all kinds of places,” Cowley said.
“Now we have to learn how to leave it
in the ground in order to survive, to save
civilization. It’s that simple.”
B
ob Mumgaard, a thirty-seven-year-
old plasma physicist from Omaha,
gets animated when talking about the
laying of the transatlantic telegraph
cable, in 1858, or the founding of Ge-
nentech, in 1976. He studied engineer-
ing at the University of Nebraska, though
his first love was physics, a field he saw
as compelling but impractical. “A lot of
the engineers who came out of my school
took jobs designing tractors,” he said.
In 2008, Mumgaard was working in a
lab studying computer hard drives when
the MacBook Air came out, with its
solid-state hard drive: “I said to myself,
‘O.K., normal hard drives are dead now.
I need to go and do something else.’”
He applied to graduate programs in
physics. He was accepted at Stanford,
where he could investigate questions of
cosmology and dark matter; he was also
accepted to M.I.T.’s P.S.F.C., where he
could work on nuclear fusion. The Mid-
western pragmatist in him chose fusion
over foundational questions about the
universe, though he was not particularly
motivated by the climate emergency.
“Sometimes I think about the way we
talked about climate back then, and I
can’t believe we wasted so much time
debating, like, whether or not Penn State
had the best climate model,” he told me.
By the time he was a student in Den-
nis Whyte’s design course, his perspec-
tive had changed—he saw fusion as
something that needed to have hap-
pened yesterday.
He was also a student in a program
with an iffy future. After M.I.T. was
told that it would lose funding for its
experimental fusion device, the P.S.F.C.
negotiated an extension to 2016, but it
was clear there would be
no further reprieve. “We
had this opportunity forced
on us,” Mumgaard said.
“We lost our funding just
at the moment that we had
this big shiny new lever, this
new superconducting ma-
terial that could move fu-
sion forward.” By 2014,
Mumgaard and his col-
leagues could write down
their plans for ARC/SPARC in the form
of a concrete risk retirement plan—a
venture-capital term for tightly focussed
research, with discrete benchmarks. “At
M.I.T., venture capital is something
you learn about at the university bar,”
Mumgaard said. As they saw it, the big-
gest risk to retire would be making an
H.T.S. magnet for SPARC.
In 2015, the Institute of Electrical and
Electronics Engineers Symposium on
Fusion Engineering was held in Aus-
tin, Texas. Many key members of the
plasma-physics community were there,
and there were two especially notewor-
thy talks. The first was by the Austrian
physicist Guenter Janeschitz, who not
only sounds but also looks like Arnold
Schwarzenegger. He gave a presenta-
tion on DEMO, a proposed fusion de-
vice that would be almost twice the
size of ITER and produce five gigawatts
of power. Janeschitz envisions that, if
funded, a prototype could be built in
twenty years. Demo is widely seen to be
a clear-eyed, workable plan, and a step
on the path to bringing practical fu-
sion energy to your great-grandchildren.
Dennis Whyte gave a presentation
on ARC. He estimated that it could
demonstrate net fusion energy in 2025
and bring fusion to the electric grid by
2030, with individual plants producing
a gigawatt of power each—about what
a conventional power plant provides
today. DEMO would cost an initial thirty
billion dollars; ARC would be a million-
dollar machine. “It was very dramatic,”
Mumgaard said. “The difference was so
stark. The room was split.” Roughly
speaking, the younger people were buzz-
ing with hope; the older people had per-
haps been hopeful one too many times.
The doubters weren’t simply kill-
joys—they were imaginative thinkers
who had devoted decades of their lives to
fusion research. It wouldn’t be easy to
make H.T.S. into a magnet
of sufficient size. And the
powerful magnetic field cre-
ated by H.T.S. was sure to
have consequences, which
hadn’t been fully studied.
There was every reason in
the history of experimen-
tal science to expect sur-
prises. And funding for fu-
sion projects was already
tight; another idea might
draw money away from projects that
many scientists considered more prom-
ising. It was entirely reasonable to ask
whether the members of the M.I.T.
team were the Wright brothers or Sam-
uel Pierpont Langley—the head of the
Smithsonian who in 1903 crashed his
very expensive Aerodrome into the Po-
tomac, and then a couple of years later
did it again.
After Whyte’s keynote, the M.I.T.
crowd went out for lunch at Stubb’s
Bar-B-Q. “It’s the kind of place with
red-checked tablecloths and food that
comes with a lot of napkins,” Whyte
said. Everyone around the table knew
that the primary funding for their work
would end within a year. As Mumgaard
recalls, “Basically, we all had pink slips,
and yet we were still there. And the
question was, Why? We had to learn to
listen to ourselves. Did we really believe
the field was where we were saying we
thought it was?” Was H.T.S. really the
shiny new lever that would move fu-
sion dramatically forward? Whyte and
his colleagues started to write on a nap-
kin details of how they could make
SPARC and then ARC a reality. They
wrote down estimates of how much
money it would cost to develop it. “It
was like this collective dawning, that
this thing was really possible,” he told
me. Over ribs, they decided that they
would fund their work with lottery
tickets or with venture capital or with
