6 AUSTRALIAN SKY & TELESCOPE May | June 2018
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STEPHEN HAWKING,renowned and
inspirational physicist, died on March
14 at the age of 76. He spent decades
defying expectations and living a
remarkably full life, and is survived by
threechildrenandthreegrandchildren.
HawkingwasbornonJanuary8,
1942,inOxford,England.Though
clearly gifted, he didn’t apply himself
inschooluntilhereachedcollege,
wherehestudiedphysicsandgraduated
with honours. He went on to graduate
school at the University of Cambridge.
It was then, at age 21, that Hawking
was diagnosed with amyotrophic lateral
sclerosis (ALS), a disorder that affects
nerves in the brain and spinal cord,
leaving muscles to weaken and waste
away. Hawking was told at the time
that he would have one, maybe two
years to live.
Yettwoyearslater,Hawkingwas
feelingrelativelywell,engagedtobe
marriedtoJaneWilde,andcasting
about for a thesis idea. That’s when he
came across Roger Penrose’s work on
singularities. While his thesis focused
on the Big Bang singularity, this interest
naturally led him to black holes, which
would occupy most of his career.
EvenasALSconfinedhimtoa
wheelchair by the 1970s, Hawking
begantocontemplatetheideasbehind
the concept he’s most famous for:
Hawking radiation.Inthisprocess,black
holes lose energy (and therefore mass)
by interacting with virtual particles.
Thevacuumofspaceisnottotally
empty;virtualparticlespopintoand
out of existence. These short-lived
particles come in pairs that quickly
recombine and annihilate, resetting
the energy scorecard to zero. But near
a black hole’s horizon, tidal gravity
pulls apart the particles, boosting their
energy such that they survive and
become ‘real’. One is lost into the black
hole and the other flies away, carrying
theenergyithastakenfromtheblack
hole’s gravity — thus reducing the black
hole’s mass.Eventhorizon
Hawking
radiationVirtual
particle
pairsInfalling
particleSStephen Hawking addresses a crowd at
Northeastern University in 1991.In Hawking’s concept
of black hole
radiation, the lucky
one of a virtual pair
of particles produced
near the event horizon
(a black hole’s ‘point
of no return’) may
escape, appearing to
radiate from the black
hole itself.HAWKING: KELLY BEATTY /S&T; ILLUSTRATION: GREGG DINDERMAN /S&THawking radiation is difficult, if
not impossible, to observe but has
huge implications for physics. If black
holes radiate their mass away, that
would destroy the information the
mass once held — something quantum
mechanics forbids. Even now physicists
are struggling to understand the
implications in their quest for a true
unification of general relativity and
quantum mechanics.
Hawking completely lost his ability
to speak in 1985 and relied solely on acomputerised voice system. It slowed
his communication, but in 1988 he
nevertheless published the best-selling
and foundational A Brief History of
Time, which walks through the origin
and structure of the universe, space,
and time with clarity and a good dose
of wit.
Hawking divorced Jane, his wife
of 30 years, in 1995 and married his
one-time nurse, Elaine Mason. He and
Mason divorced in 2006. However,
Jane and Hawking maintained a
good working relationship, and Jane’s
autobiography, titled Travelling to
Infinity: My Life with Stephen, resulted
in the 2014 movie that celebrated
Hawking’s life, The Theory of Everything.
Although he continued his
research on black holes, recent years
saw Hawking turn his gaze toward
humankind’s future, motivated by
concerns over our planet’s long-
term habitability. He advocated a
push for the stars and helped launch
Breakthrough Starshot. At his 75th
birthday celebration, he reminded
attendees, “Remember to look up at the
stars and not down at your feet. Try to
make sense of what you see and wonder
about what makes the universe exist. Be
curious, and however difficult life may
seem, there is always something you
can do, and succeed at. It matters that
you don’t just give up.”
■ MONICA YOUNGStephen Hawking, 1942–
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