THE SOUTHWORTH PLANETARIUM
207-780-4249       www.usm.maine.edu/planet
70 Falmouth Street  Portland, Maine 04103
43.6667° N,                    70.2667° W
Founded January 1970
             "Officially listed as one of the greatest wonders of the
ancient world."





THE DAILY ASTRONOMER
Wednesday, January 27, 2016
Moon in a Soup Can


You realize that for awhile, we believed we were about to puzzle it
all out.  Ever since Thales of Miletus, Aristotle, and those lot
combined insatiable human curiosity with disciplined philosophy, we've
striven to completely understand our physical reality.     From the
unfathomably small subatomic particles to remotest stars, we happy
presumptuous humans thought ourselves close to having the entire
cosmos wrapped, shipped, and its manifest filed.  And, then our
understanding collapsed, leaving a largely mysterious Universe to
regard us quizzically as though challenging us to try again.


What could be better?


Our confidence peaked toward the Victorian period's end, in the 19th
century's last decade.   Just as the patent office declared that all
that could be invented had been invented long before airplanes,
computers, and satellites transfigured our lives, the
pre-Relativistic, pre-quantum science community predicted that
twentieth century physics would be a crashing bore.  They envisioned
sad, frustrated, and ultimately pathetic 20th century physicists
spending their time measuring the gravitational constant with slightly
more accuracy and wasting themselves in taverns, lamenting that they
hadn't been born two generations earlier.



The reality differed from the prediction. The two most significant
20th century advances were the Relativity theories (Special 1905;
General 1916) and Quantum theory (1900…and many other years).
Today, we fly past the relativity and leap into the quantum.    For,
even though astronomers astonished humanity with its expansive fields
of galaxies, more profound surprises awaited us as we scrutinized the
atomic realm.   Just as our Milky Way Galaxy was seen to be a mote
amongst many, even though we once believed it to enclose the Universe
entire; our comfortable notion of a minor solar system in every atom
was shattered irrevocably:    electrons as clouds instead of planets;
a nucleus weighed down by phantasmic quarks and between them a spatial
expanse as vast, comparatively, as that separating a stadium's
perimeter and a marble on the 50-yard line.    Astronomy was showing
more space beyond.  Quantum theory was revealing more space within.



We know the word "quantum" conjures exotic notions such as time travel
and body switching, but the essence of quantum theory is simple:  that
energy is discrete, not continuous.*   Energy travels in small
"packets," or quanta.  That light energy  propagates in bundles,
called 'photons,' while retaining wave-like properties is quantum
mechanics' basis.     And, moreover, material objects, themselves,
exhibit wave-like behaviour, as well. For instance, electrons are
hardly little negatively charged spheres whirring around a nucleus,
but instead are "smeared out" along specific energy levels.

Apart from defining an atom's vague, changeable perimeter, electrons
also impart "solidity"  onto objects that are predominantly empty
space.     Strike a table with your hand.  Both your hand and the
table are essentially nothing: the protons, quarks, and other material
components occupy a minuscule volume of the space within both.   The
photon exchange between electrons makes them seem solid.    This
electron interaction  solidifies our nearly empty world.


Ironically, even though vast space separates celestial bodies, vast
space comprises these celestial bodies:  except, of course, for the
neutron stars.    These stellar remnants form when a highly massive
star collapses onto itself.   This collapse compresses interior
material down into a volume no larger than a city.    (Imagine the
material equivalent to half a million Earths contained within a
Manhattan-shaped sphere.)    These unfathomably dense neutron stars,
or pulsars, are devoid of empty space and therefore are the only
examples of solid objects that are completely solid.

Comprehending such densities is, well, impossible for most of us.
Such extremes defy intuition, and we're left with analogies that might
help us appreciate these densities, if not understand them.

Holding a teaspon of neutron star matter would be difficult: the mass
of this small teaspoon would equal that of an entire mountain.*
And, for another more stunning example, if you compressed the Moon
down to a neutron star's density (i.,e. the Moon without any empty
space within it), you could place it inside a…well, actually, you
probably know if you read the title.

And, here's the kicker:     all the matter of all the humans who've
ever lived and those now living would, if compressed, fit inside a
sugar cube  volume.      Humanity all but vanishes if its empty space
is kneaded out of it.



How lovely to think that existence is, indeed, an airy nothing




*"Discrete" vs. "continuous"          The number of people in a room
is an example of something discrete, as people are separate objects.
  A straight line is continous, as it consists of an infinite number
of points.