Energy and Human Ambitions on a Finite Planet, 2021a

Alluring Tangents
D
This Appendix contains tangential information that may be of interest
to students, but too far removed from the main thread of material to
warrant placement within chapters. Many of these items were prompted
by student feedback on the first draft of the textbook, wanting to know
more about some tantalizing piece mentioned in the text. Pick <strong>and</strong>
choose according to your interests.
D.1 Edge of the Universe
Sec. 4.1 (p. 54) built a step-wise scale out to the edge of the visible
universe, which a margin note clarifies as the visible horizon of our
universe. This fascinating <strong>and</strong> deep concept deserves elaboration.
Two foundations of experimental physics <strong>and</strong> cosmology are that the
speed of light is finite, <strong>and</strong> the universe began in a Big Bang 13.8
billion years ago. Ample evidence supports of both claims. It should be
noted that these notions were not at all accepted by scientists until the
preponderance of evidence left little choice but to adopt them as how
the world really appears to work.
D.1 Edge of the Universe .... 392
D.2 Cosmic <strong>Energy</strong> Conservation393
Cosmological Exception .. 394
Convoluted Conservation . 395
Lost to Heat .......... 396
D.3 Electrified Transport .... 397
Airplanes ........... 398
Shipping ............ 399
Long-haul trucking ..... 399
Buses .............. 400
Passenger Cars ........ 400
Wired Systems ........ 402
Collected Efficiencies .... 402
D.4 Pushing Out the Moon ... 402
D.5 <strong>Human</strong>ity’s Long View ... 404
Success vs. Failure ...... 404
Sustainable Living ..... 406
Time to Grow Up ...... 407
Frameworks .......... 407
D.6 Too Smart to Succeed? ... 408
Evolution’s Biggest Blunder? 411
The finite speed of light means that looking into the distance amounts
to looking back in time. Here, Imperial units have a brief moment of
glory, in that every foot of distance (0.3 m) is one nanosecond of time.
We see the moon as it was 1.25 seconds “in the past,” the sun as it was
500 seconds (8.3 minutes) ago, <strong>and</strong> the nearest star 4.2 years back. The
“nearby” Andromeda Galaxy is 2.5 million years in the past, <strong>and</strong> as we
peer farther into the universe we look ever farther back in time. Indeed,
at great distances we see infant galaxies in the process of forming as
gravitational vacuum cleaners collecting materials from the diffuse gas
that came before.
So what happens when we look 13.8 billion years into the past, when the
Big Bang is alleged to have happened? Shouldn’t we see the explosion?
And shouldn’t it—perhaps confusingly—be visible in all directions?
The answer is a resounding, though qualified, YES. Yes, we see evidence
of the Big Bang in all directions, as a glow that appears in the microwave
region of the electromagnetic spectrum. The Cosmic Microwave Background,
or CMB, as it is called, represents the glowing plasma when the
universe was just 380,000 years old <strong>and</strong> about 1,100 times smaller than it
is today. We cannot see earlier than this because the hot ionized plasma