I don't think anyone really knows. There are lots of ideas, though. If there has only been one Big Bang (which in itself seems unlikely to me), then the Universe has an average radius, approximately the age of the universe times the speed of light, ignoring the possibility of stuff that travels faster than the speed of light. Intergalactic space is thought to have an average density of something like 1 hydrogen atom per cubic meter [citation needed] although recent news from the big telescopes suggests that there are stars and planets also outside of galaxies. 1 atom/m^3 is pretty empty. If the universe is alone, I suspect there is no way we will ever see its edge, as it is receding from us at or faster than the speed of light.
There are cosmologists who believe in all seriousness that our universe is expanding like a bubble in a foam of universes, in which case it is possible, I suspect, that we will some day detect the boundary, where it impinges on another universe. Does the edge slow down? Is there a shock wave? Please forgive me for being so Newtonian about this, but I can't imagine a foam of universes where all of them can expand indefinitely at or above the speed of light. Not, at least if they all share the same dimensions*. Then the question begs to be asked, does the foam have a boundary? What would be beyond that?
"It's turtles all the way down."
*What if our three familiar dimensions are actually dimensions #38576027184365756392, #38576027184365756393, and #38576027184365756394, and other universes are also three dimensional but occupy other dimensions than our particular three of length, width, and height? (I am ignoring the 9, 11, 17 or whatever dimensions are required by string theory.)
These are questions and our answers about science and history that have been asked of the Bradbury Science Museum's education staff.
Monday, March 2, 2015
How many moons are there in space?
Space is a really
big place. There are billions of galaxies and each one has billions of stars.
Recent discoveries suggest that planetary systems are the rule and not the
exception around stars. So the number of moons in space is uncountable.
I suspect you meant
to ask how many moons there are in our solar system. When I was young, a long
time ago, books about the solar system gave precise numbers for the moons of
each planet. Then came the Pioneer and Voyager spacecraft and vastly better
telescopes. The answer is no one knows. It seems every time we a get closer look
at the distant planets, like Saturn, Uranus, or Neptune, we discover they have
more moons than we previously thought. Even Pluto is now known to have at least
two moons.
This Friday (March
6, 2015) the dwarf planet Ceres, the largest body in the Asteroid Belt, will
get a new moon, or at least a satellite. NASA’s Dawn spacecraft will slip into
orbit around this body for a visit.
Why is there so little information about the Navajo Code Talkers here?
Jourdan, I am so proud of you! Thank you for asking why we don't feature the Navajo Code Talkers at our museum. You are the first person to ask this in my ten years as the question answerer, and it is a good question.
You are correct
that we feature mostly Manhattan Project related information in our history
exhibits, and that is actually the short answer. You might like to know that we
occasionally get criticized for not talking more about the Holocaust in our
museum. I am fascinated that while we seem to brag about "ending the
war," very few people if any suggest we could talk more about the aspects
that actually won the war, the Navajo Code Talkers being a major contribution
along with, for example, shipbuilding and the secret developments of radar and
code breaking.
WWII, particularly
in the Pacific, was a truly horrible affair. I cannot imagine the feelings of
the Marines who bore the brunt of one amphibious assault after another against
entrenched and fanatical fighters. They were extremely lucky to have the Code
Talkers with them, and the ability to communicate securely because the Navajo
People, Your People, had protected and maintained their ability to speak in
their own tongue, often in the face of harsh government opposition.
I will place a copy
of this text in our answer book. It is not much, and nowhere near what they
deserve, but the Navajo Code Talkers earned at least this little honor.
Labels:
Navajo,
Navajo Code Talkers,
WWII
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