Scientific American Space & Physics 2020 04-05.pdf

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APRIL/MAY 2020 | SCIENTIFICAMERICAN.COM
Plus:
Space
&
Physics
WHY WE CAN’T
SETTLE ON MARS
MERGING
SUPERMASSIVE
BLACK HOLES
TO SEND OUT
A FLARE
STUNNING NEW
IMAGES OF
OUR SUN
The
Supercold
Quantum
Realm
Ultracold atomic systems
are pushing the boundaries
of known physics and may
even set the stage for
quantum computing
WITH COVERAGE FROM
FROM
THE
EDITOR
&PHYSICS
Your Opinion
Matters!
Help shape the future
of this digital magazine.
Let us know what you
think of the stories within
these pages by emailing us:
editors@sciam.com.
SPACE
The Most Mercurial Field of All
In early March,
Scientific American
put the finishing touches on a very exciting collector’s edition entitled “Quantum
Universe,” due out on newsstands at the end of April (not so subtle sales pitch there). In assembling and editing the
diverse articles for that issue, I came to notice a common theme in the field of quantum physics: the sense that our
grasp, from an observational standpoint, of the quantum universe is tenuous and fleeting—the second you try to ob-
serve entanglement, the wave function collapses. Because of this phenomenon, researchers are desperate to devise
new ways to gather quantum measurements. And so the discipline of ultracold quantum physics has proved a very
satisfying direction of research. As Karmela Padavic-Callaghan writes in this issue’s cover story, investigators can
manipulate superchilled atoms and use them as models for quantum systems (see “The Coolest Physics You’ve Ever
Heard Of”). Having such control over a quantum experiment is gratifying.
Elsewhere in this issue, planetary scientist Carolyn Porco gives an account of corresponding with Carl Sagan about
capturing an image of Earth from space (see “How the Celebrated ‘Pale Blue Dot’ Image Came to Be”), and Nola
Taylor Redd reports on another compelling galactic image: two merging black holes that are sending whorls of dust
and gas into view (see “Meet ‘Spikey,’ a Possible Pair of Merging Supermassive Black Holes”). Some things in the
universe are very concrete indeed.
Andrea Gawrylewski
Senior Editor, Collections
editors@sciam.com
LIZ TORMES
On the Cover
GETTY IMAGES
Ultracold atomic systems
are pushing the boundaries
of known physics and may
even set the stage for
quantum computing
2
NSO, NSF AND AURA
WHAT’S
INSIDE
NEWS
4.
Home Star
Stunner: Best-Ever
Images of Solar
Surface Herald
New Era
Scientists have released
the first pictures from a
new telescope in Hawaii,
one of three missions
expected to redefine our
understanding of our
home star in the 2020s
6.
Bizarre Cosmic
Dance Offers Fresh
Test for General
Relativity
Scientists have detected
relativistic frame
dragging, a prediction of
Einstein’s greatest
theory, around a distant
pair of exotic stars
April-May 2020
Volume 3
•
No. 2
OPINION
28.
Death on Mars
The Martian radiation
environment is a problem
for human explorers that
cannot be overstated
ESO/M. MONTARGÈS ET AL.
FEATURES
15.
The Coolest Physics You’ve Ever Heard Of
Ultracold atoms can simulate all kinds of
quantum behavior
19.
How the Celebrated “Pale Blue Dot”
Image Came to Be
Voyager 1’s poignant photograph of the distant
Earth as the spacecraft sped toward interstellar
space happened just 30 years ago
22.
Meet “Spikey,” a Possible Pair of Merging
Supermassive Black Holes
A flare predicted for this spring could confirm that
the object is indeed two monstrous black holes
coming together
25.
The Curious Case of Proxima C
Astronomers continue to gather evidence
for a second world around the sun’s nearest
neighboring star
NASA
30.
Have We Solved
the Black Hole
Information Paradox?
The answer is maybe.
As a bonus, we may soon
have a new understand-
ing of nature at a qualita-
tively different and
deeper level than ever
33.
What’s Wrong
with Physics
A physicist slams hype
about multiverses, string
theory and quantum
computers and calls for
more diversity in his field
38.
Celestial
Movement
The sky is always
changing. To appreciate
the view, check out these
stargazing calendars,
go outside at night and
look up!
Astronomical events:
April, p. 39; May, p. 40.
10.
New Horizons May
Have Solved Planet-
8.
Mysterious Faded
Formation Cold Case
Star Betelgeuse
An encounter with
Has Started to
Arrokoth at the outskirts
Brighten Again
of the solar system
“Orion’s shoulder” had
reached unprecedented offers the best evidence
dimness in mid-February, yet for how worlds
coalesce from dust
leaving astronomers
befuddled
13.
Physicists Come
Closer to Answering
Question of
Antimatter’s Scarcity
Researchers have
confirmed a long-
predicted key similarity
between hydrogen and
antihydrogen
NASA
3
NEWS
Home Star Stunner:
Best-Ever Images
of Solar Surface
Herald New Era
Scientists have released the first
pictures from a new telescope in
Hawaii, one of three missions expec-
ted to redefine our understanding
of our home star in the 2020s
Why is the sun’s outer atmosphere
so much hotter than its surface?
What drives its 11-year cycle of
magnetic activity? And how does its
solar wind propagate out into the
solar system? Scientists hope to
answer all these questions and more
in the coming decade, thanks to an
armada of new missions that will
scrutinize the sun in more detail than
ever before. With the debut of two
unprecedented spacecraft and the
largest ground-based solar observa-
tory ever built, research into our
home star is set to reach new heights.
One of the two spacecraft has
already launched:
nASA
’s Parker
Solar Probe, which soared skyward
Features as small as 30 kilometers are visible in this video, composed of the
highest-resolution images of the sun’s surface ever taken. Each of the bubblelike
granules of convecting plasma seen here is roughly the size of Texas.
NSO, NSF AND AURA
4
NEWS
on August 12, 2018. Designed to
approach our star within just 4 per-
cent of the Earth-sun distance, or
0.04 astronomical units (AU), it is the
closest mission ever sent to our star.
The other craft, the European Space
Agency’s (ESA’s) Solar Orbiter
mission, launched from Cape
Canaveral, Fla., in February. Though
projected to reach only 0.28 AU, this
mission will capture some of the
most detailed images of the sun
ever seen, including the first pictures
of its poles. And now scientists have
released inaugural images from the
four-meter Daniel K. Inouye Solar
Telescope (DKIST) on Maui in
Hawaii. Run by the national Science
Foundation in the U.S., this instru-
ment has taken the most detailed
images ever of the solar surface.
“It’s extremely exciting to be a solar
physicist at this point in time, with all
of these missions,” says Thomas
Rimmele, an astronomer and project
director of DKIST at the national
Solar Observatory. “With just the first
images [from DKIST], you see detail
that we’ve never seen before. And
this is really just the beginning.”
DKIST’s five instruments are
designed to both image the sun and
probe its magnetic field, allowing
scientists to discern the field’s
strength and orientation. Scientists
hope to use these data to help
resolve the long-standing mystery
of why the sun’s corona—its halolike
outer atmosphere—is up to millions
of degrees hotter than its surface.
Data from DKIST will also allow
researchers to probe the magnetic
fields of the vast structures that arc
and loop between these two regions.
Complementing DKIST are the
aforementioned Parker Solar Probe
and Solar Orbiter. By repeatedly
flying close to the sun over the next
five years at record-setting speeds of
nearly 700,000 kilometers per hour,
the former will be able to measure
pristine material ejected from our star,
and it is already providing invaluable
data from its early passes. “Parker
Solar Probe is showing us signatures
of the solar wind and the plasma in
the corona that we’ve never seen
before in previous missions,” says
nour Raouafi, project scientist for the
probe at the Johns Hopkins Universi-
ty Applied Physics Laboratory.
Meanwhile the Solar Orbiter has
the capability to directly image the
sun from its close-up vantage
point—something the Parker Solar
Probe lacks. Poking through small
holes in the spacecraft’s titanium
heat shield, cameras will provide the
closest images of the sun ever taken.
Beyond the delivery of such stunning
snapshots, scientists are already
excited about other insights this
mission might reveal, such as how our
star launches flares and coronal mass
ejections—“space weather” events
that can severely disrupt global
power grids and telecommunications.
“The main problem with space
weather at the moment is [we have]
a 12-hour warning at most,” says
Stephanie Yardley, a solar physicist
at the University of St. Andrews in
Scotland. “If we [know] the evolution
of the magnetic field of the sun and
the solar atmosphere, we can gain
some insight into how these erup-
tions are actually formed. It’s current-
ly very difficult [to predict them].”
The Solar Orbiter has one more
trick up its sleeve, too. It will use
repeated encounters with Venus to
gradually raise the inclination of its
orbit, eventually reaching 33 de-
grees above the plane of the planets
if, as hoped, the mission is extended
beyond its initial seven years. Doing
so will enable it to orbit the sun at a
high angle, capturing images of the
sun’s poles. “We’re hoping to see
how the magnetic field on the surface
migrates toward the poles and
eventually influences the ‘flip’ of
the sun’s poles [every 11 years],”
Yardley says.
numerous sun-observing space-
craft have been launched before, but
without the advanced capabilities of
these new missions. ESA and
nASA
’s
widely regarded and still operational
Solar and Heliospheric Observatory
(SOHO) launched in 1995, but it sits
at a distant 0.99 AU from the sun.
The German-U.S. Helios probes in the
1970s, meanwhile, set the previous
record for the closest approach to the
sun of 0.29 AU, yet they have since
been eclipsed by the Parker Solar
Probe. And ESA and
nASA
’s Ulysses
spacecraft used a gravitational assist
from Jupiter to fly over the sun’s
poles in the mid-1990s and early
2000s, but it did so without cameras
to image what they looked like.
Together, Raouafi says, these new
missions herald an upcoming “golden
age” of solar studies. “They have the
potential to define the future direction
of solar and heliophysics research,”
he says. And Gregory Fleishman of
the new Jersey Institute of Technolo-
gy hopes they might inspire even
more projects in the near future. He
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