Sky & Telescope - September 2021 - 22

BACKGROUND IMAGE: JONATHAN KNOWLES / GETTY IMAGES;
TIMELINE: TERRI DUBÉ / S&T
Temperature (K)
MAGNETOGENESIS by David Garrison
The First 10 Se
T
Scientists are using their knowledge
of fundamental physics to study the
universe's earliest moments and the
origin of the first magnetic fields.
he universe is a complicated place. Crashing galaxies,
exploding stars, lava-erupting worlds - the cosmos is
messy. Go back 13.8 billion years, though, and things
were a lot simpler. All that existed was hot plasma. Energetic
particles filled this primordial soup, interacting in conditions
so extreme that we are just now beginning to approach them
in gigantic particle colliders on Earth.
This statement naturally leads to the question, " How do
we know what the universe was like 13.8 billion years ago? "
For humans, anything older than a few thousand years is
prehistoric. We know about things like the U.S. Space Shuttle
program directly from people who worked on it. We know
about the U.S. Civil War because of the documents left by
those who lived through it. But when it comes to older history
- like the migration of the first humans to leave Africa
or the extinction of the dinosaurs - we have to rely on fossil
records to tell the story. Understanding the early universe is
even more difficult than that.
Our oldest fossil is the cosmic microwave background
(CMB), the radiation released when the early universe cooled
down enough for photons to travel freely. People often refer
to the CMB as the universe's baby picture. But the CMB
comes from a time when the universe was about 380,000
years old: It's a snapshot of a moment long after the universe
was a newborn. To really gain an understanding of what the
early universe was like, we need to use an even more powerful
tool. Perhaps the most powerful tool humans have ever
created. Physics.
The Universe's
First Moments
?
Planck time
(smallest
measurable
unit of time)
Time (s)
1040
1020
101
1030
1010
t=0
Quantum
gravity?
10-43
1032
GRAND
UNIFICATION
EPOCH:
Electroweak
and strong
forces united
10-40
10-35
10-30
10-20
INFLATION
ENDS
Using our most basic
understanding of the laws of
nature . . . we can turn back the
clock and compress the cosmos.
1029
1027
22 SEPTEMBER 2021 * SKY & TELESCOPE

Sky & Telescope - September 2021

Table of Contents for the Digital Edition of Sky & Telescope - September 2021

Contents
Sky & Telescope - September 2021 - Cover1
Sky & Telescope - September 2021 - Cover2
Sky & Telescope - September 2021 - 1
Sky & Telescope - September 2021 - Contents
Sky & Telescope - September 2021 - 3
Sky & Telescope - September 2021 - 4
Sky & Telescope - September 2021 - 5
Sky & Telescope - September 2021 - 6
Sky & Telescope - September 2021 - 7
Sky & Telescope - September 2021 - 8
Sky & Telescope - September 2021 - 9
Sky & Telescope - September 2021 - 10
Sky & Telescope - September 2021 - 11
Sky & Telescope - September 2021 - 12
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Sky & Telescope - September 2021 - 20
Sky & Telescope - September 2021 - 21
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Sky & Telescope - September 2021 - 28
Sky & Telescope - September 2021 - 29
Sky & Telescope - September 2021 - 30
Sky & Telescope - September 2021 - 31
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Sky & Telescope - September 2021 - Cover3
Sky & Telescope - September 2021 - Cover4
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