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
Julian date: 2457726.16
"I went to a restaurant that serves 'breakfast at any time'.
So I ordered French Toast during the Renaissance."
-Steven Wright
THE DAILY ASTRONOMER
Tuesday, December 6, 2016
Fantastical Pandoras
We must be careful whenever we are tempted to dismiss a question as absurd
or an idea as "mad." Seemingly silly questions or preposterous notions
have often resulted in great advances in our understanding of this wholly
strange Universe in which we have found ourselves. For instance, Special
Relativity, one of the 20th century greatest achievements, started in part
when Einstein asked, " How would a light beam appear to an observer capable
to running alongside it at the same speed?"
During this dip into Pandora's Jar, we encounter two questions that might
seem outlandish to the point of being fantastical. However, each
question afforded us the opportunity to look at the world in a different
way. Any question that does that is certainly worth asking.
*PANDORA PARCHMENT # 9:*
*"Ok, this is the most narcissistic question you have probably ever
received. I know that astronomers have 'found' dark matter by seeing
how that matter affects the visible stars. The more matter in the
galaxy, the faster the stars move. Well, I was wondering...when I die,
the galaxy will have less matter and therefore will my death cause the
galaxy to turn more slowly?" -I Anonymous*
Greetings!
Yes, it is true that a galaxy's rotation rate, or, more precisely, the
velocities of the stars within the galaxy, are related to the galaxy's
mass. The loss of any material within the galaxy will reduce its mass
and could decrease the stellar velocities. However, the material
comprising a human remains within the galaxy even after the human's death.
In fact, the particles comprising your body existed for billions of
years before your birth and will persist for billions of years more after
your death. Our constituent matter remains within the galaxy, albeit
in different forms
All the same, let's assume that some renegade human teleports out of the
Milky Way Galaxy to a distant point. Now, the Milky Way has indeed lost
some material. However, the loss is certainly negligible and wouldn't
affect the galaxy rotation at all. Even if every human grew tired of this
galaxy and emigrated to another galaxy, our home galaxy -or, what was our
home galaxy- wouldn't be affected at all. You realize that the mass of all
the humans who have ever lived and are now living is equal to about one
cubic centimeter of neutron star material. We don't add much heft
to this barred spiral galaxy we call home.
*PANDORA PARCHMENT # 10:*
*"Will all the powder on a doughnut rise off the doughnut in zero gravity?"*
* -Radio listener*
Hello!
That is actually a good question. To answer this question, we're going
to pretend that an astronaut aboard the International Space Station is
about to help herself to a beautiful powered doughnut. Before engorging,
she snaps the doughnut to shake off some of the powder. What happens?
Well, as she is in micro-gravity, the powder doesn't just fall back onto
the doughut as would happen on Earth. The displaced powder moves away
from the doughnut and only stops moving due to collisions with the air
within the station. However, the powder already on the doughnut will
remain there because it is trapped on the doughnut's surface in the many
little peaks and valleys that are hidden within almost all solid objects.
(When you slide a book across a desk, it will eventually come to a stop
because the irregularities within the book's surface and the desk's surface
will rub against each other, causing the book to lose energy and eventually
come to a stop. This is a result of kinetic friction...the friction of
motion.)
*Gorgeous powdered doughnut. If floating in*
*micro-gravity, the powder would remain on the doughut*
*unless something shakes it off. Image by dreamstime.com
<http://dreamstime.com>*
Even in micro-gravity, the powder particles won't just lift off the
doughnut's surface. Some force would have to raise the powder from the
surface, No object, be it a grain of sugar or a baseball, can move on its
own volition Some force must be applied to it in order to impart
motion on it if stationary or to impede its motion if it is moving.
The astronaut who shakes the doughnut imparts a force on the doughnut and
causes some of the powder to move off the doughnut surface. It won't
do that on its own.
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COMING FEBRUARY 2017 TO THE SOUTHWORTH PLANETARIUM
*A full dome theme park adventure! Rollercoasters and other thrill rides
through the solar system.*
*Showings each day during February school vacation week*
*Feb 20 - 24, 2016*
*Consult www.usm.maine.edu/planet <http://www.usm.maine.edu/planet> for
more information!*
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© 2016 Edward Gleason