Sky and Telescope - July 2016 - 4

Peter Tyson
Spectrum
Founded in 1941
by Charles A. Federer, Jr.
and Helen Spence Federer

The Essential Guide
to Astronomy

To the Unknowable
Astronomers treasure

L. REZZOLLA (AEI) & M. KOPPITZ (AEI & ZUSE INSTITUTE BERLIN)

the idea of "unknown unknowns."
These are astronomical objects and events that appear out of left ﬁeld, totally
new and unforeseen. An example is fast radio bursts (see page 24), about
which we knew nothing before 2006. That year an undergraduate at West
Virginia University, combing through hundreds of hours of archived radio
data from Australia's Parkes Observatory, chanced upon the ﬁrst recognized
instance of these ultrabrief, super-bright ﬂashes of radio waves.
There are "known knowns," or everything we've observed, studied,
and think we understand. And there are
"known unknowns," things we expect to
uncover based on theory or hunch but haven't
yet. Gravitational waves languished in this category for a century until LIGO detected them
last September (S&T: May 2016, p. 10).
But the greatest potential for discovery,
for knocking our socks oﬀ, comes with the
unknown unknown. The lure of revealing the
entirely novel, the wholly unexpected, is part of
what drives the development of ever larger teleDo colliding neutron stars
scopes such as the Large Synoptic Survey Tele(simulated here) trigger fast
scope and the Square Kilometer Array. These
radio bursts? One more deepand other next-generation scopes will enable
space enigma for us to tackle.
astronomers to probe previously unobservable
swaths of the universe, identify new and exotic
classes of objects, pick out that one-in-a-billion outlier or anomaly.
But there's a fourth category that most draws me, and perhaps many
of you, to the mysteries of the universe: the unknowable. Chet Raymo
phrases it well in his book The Soul of the Night, in which he describes
his decades-long quest to ﬁnd human meaning in the cosmos: "The
pilgrimage is one that each of us must make alone, into the realm of the
stars and galaxies, to the limits of the universe, to that boundary of space
and time where the mind and heart encounter the ultimate mystery, the
known unknowable."
We know we have questions about the universe and our place in it for
which we may never secure answers. And a good thing, too: we need inexplicable phenomena to expand our minds and remind us that our cleverness has limits. Is our universe just part of a multiverse? Why does time
exist? Why does anything exist? Do we matter?
Altogether, it's a ﬁrmament of inscrutabilities out there, and no matter
how many we get to the bottom of, there will always be others that remain
tantalizingly unfathomable. As H. L. Mencken once wrote, "Penetrating
so many secrets, we cease to believe in the unknowable. But there it sits
nevertheless, calmly licking its chops." ✦

EDITORIAL

Editor in Chief Peter Tyson
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Observing Editor S. N. Johnson-Roehr
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Ted Forte, Sue French, Steve Gottlieb, David Grinspoon, Ken HewittWhite, Johnny Horne, Bob King, Emily Lakdawalla, Jerry Lodriguss,
Rod Mollise, Donald W. Olson, Jerry Oltion, Joe Rao, Dean Regas, Fred
Schaaf, Govert Schilling, William Sheehan, Mike Simmons, Mathew
Wedel, Alan Whitman, Charles A. Wood, Robert Zimmerman
Contributing Photographers P. K. Chen, Akira Fujii, Robert Gendler,
Babak Tafreshi
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4

July 2016 sky & telescope

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Sky and Telescope - July 2016

Table of Contents for the Digital Edition of Sky and Telescope - July 2016