IEEE Microwave Magazine - September/October 2018 - 14

I hope that the unexpected amplitude and line shape of the
reported absorption signal is indeed a hard-won breakthrough
that reveals evidence of unexpected physics. But it is possible
that systematic errors have escaped detection by the tests that
were run. Two extensions to the
reported tests include using circuitry that more precisely imitates the antenna than Bowman
and colleagues' circuitry when
attached to the receiver during
performance evaluation and calibration, and the cross-checking
of performance models for the
antenna (which are currently
based on computer simulations
of antenna electromagnetics)
with field measurements made
when narrow-band or sinusoidal signals are broadcast near
the antenna.
I am sure that readers will readily
agree with Dr. Greenhill. Electromagnetic
simulations of antenna characteristics

after the Big Bang, scientists used a
receiving antenna located in the "radio
quiet" zone of a remote desert in Western
Australia. [5]
In an accompanying theoretical paper
[3] in Nature, Barkana argues,
Our analysis also confirms that
dark matter is highly nonrelativistic and at least moderately cold,
and primordial velocities predicted by models of warm dark
matter are potentially detectable.
These results indicate that 21-centimetre cosmology can be used as
a dark-matter probe.
And, in an opinion piece [6] in Nature, Dr.
Lincoln Greenhill of Harvard University
exults about the discovery made by
Bowman et al.:
The idea that a detectable radio
signal from the cosmic dawn can
be connected to the particle properties of dark matter suggests a
potentially revolutionary angle for
exploring fundamental physics.
At the same time, Dr. Greenhill urges
caution [6]:

are great, but, to be really certain, nothing
beats making some field measurements!

References
[1] S. Lloyd. (2018, May 8). Stephen Hawking's
scientific legacy. Physics World. [Online]. Available: https://physicsworld.com/a/stephenhawkings-scientific-legacy/
[2] (2018, May 8). Stephen Hawking ponders the universe. JAXA. [Online]. Available: http://global
.jaxa.jp/article/interview/vol22/p2_e.html
[3] R. Barkana. (2018, May 8). Possible interaction
between baryons and dark-matter particles
revealed by the first stars. Nature. [Online].
Available: https://www.nature.com/articles/
nature25791
[4] J. Bowman, A. Rogers, R. Monsalve, T. Mozdzen, and N. Mahesh. (2018, May 8). An absorption profile centered at 78 megahertz in
the sky-average spectrum. Nature. [Online].
Available: http://www.nature.com/articles/
nature25792
[5] N. Greenfieldboyce. (2018, May 8). Did dark
matter make the early universe chill out? NPR.
[Online]. Available: https://www.npr.org/
sections/thetwo-way/2018/02/28/588833582/
did-dark-matter-make-the-early-universechill-out
[6] L. Greenhill. (2018, May 8). A surprising chill
before the cosmic dawn. Nature. [Online].
Available: https://www.nature.com/articles/
d41586-018-02310-9

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September/October 2018

https://www.physicsworld.com/a/stephen-hawkings-scientific-legacy/ http://global.jaxa.jp/article/interview/vol22/p2_e.html https://www.nature.com/articles/nature25791 http://www.nature.com/articles/nature25792 https://www.npr.org/sections/thetwo-way/2018/02/28/588833582/did-dark-matter-make-the-early-universechill-out https://www.nature.com/articles/d41586-018-02310-9 http://www.damaskosinc.com

Table of Contents for the Digital Edition of IEEE Microwave Magazine - September/October 2018