On 4/20/2013 1:59 AM, Hal Murray wrote:
For those of you who aren't familiar with it, the Exploratorium is the great
grandaddy of the hands-on science museums. It was started by Frank
Oppenheimer way back in 1969.
Anybody nutty enough to be on the time-nuts list would have a great time
there. They welcome big kids as well as little kids and everything inbetween.
http://en.wikipedia.org/wiki/Exploratorium
http://exploratorium.edu/ (time sink warning)
(The best exhibits are fascinating to both toddlers and PhD physicists, but
maybe not for the same reason.)
I highly recommend it to anybody in the San Francisco area, either as a local
or as a visitor. (Locals might want to wait until the "new" rush calms down,
but that might take a while.)
They recently moved to a new location at Pier 15 on San Francisco's
Embarcadero. Last Wed was their official grand opening for the general
public. They had many preview events in the previous week or two: donors,
press, members, ...
http://blog.makezine.com/2013/04/15/san-franciscos-new-exploratorium-unveiled/
A good friend of mine works there. He got me in last Sunday for the
employees and friends (and teachers) preview.
They have a good collection of pendulum exhibits, obvious bait for time-nuts.
Google for >Pendulum Exploratorium< will get lots of hits.
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One is a set of pendulums with decreasing lengths. You start them all in
sync. The lengths are carefully adjusted to an integer number of cycles in
30 seconds. After 30 seconds, they all come back in sync again.
http://exs.exploratorium.edu/exhibits/pendulum-snake/
http://www.youtube.com/watch?v=Q3KRWJ7ScB0
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You can make a pendulum of length X run slower by putting a counterbalance
weight on the other side.
Is there a similar trick with crystals?
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>From the old place:
http://jackaperkins.wordpress.com/2010/12/23/the-exploratoriums-harmonic-pen
dulum/
http://exs.exploratorium.edu/exhibits/resonant-pendulum/
I didn't see it last Sunday, but I could easily have missed it.
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One neat exhibit is poor by the Exploratorium standards because there is
nothing to do or touch, but it's so neat they have it out on the floor
anyway, and it's clearly time-nuts bait.
It's a movie, taken from above, projected onto a 5ft dia screen. The field
of view is roughly 30 feet across. It shows the hands of a clock. They are
made out of trash. 2 guys with brooms are continually adjusting it, moving
the hands to keep time.
Here is a 5 minute video.
Sweepers clock
http://www.youtube.com/watch?v=SXNT4T56EmM
Anybody want to estimate the adev? :)
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They have several coupled pendulum exhibits. Are coupled pendulums (or
oscillators?) useful for timekeeping? They sure are weird face to face.
The best one is out front as an art exhibit. It's a T with swivel arms on
each end of the T.
http://exs.exploratorium.edu/exhibits/chaotic-pendulum/
Total chaos, but fascinating.
I've seen small plastic versions. This one is big, serious, made out of
steel. It's enclosed in a plastic box so the flailing arms won't break any
human arms, fingers or skulls. It's amazingly seductive especially if you
approach when it is idle (rare), all you have to do is give the obvious knob
a gentle twist and it goes berserk.
I gather it's very good at "testing" the bearings. (Fortunately, the
Exploratorium staff is very good at fixing things. It's part of their
culture.)
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They had two honest to goodness clocks.
One was a classic tower clock driven by weights. There were motors to
automagically rewind the weights. It was packaged inside a glass box so you
could walk around and look at everything. (It was nice to look at, but there
was nothing to do/touch so it was low on the Exploratorium goodness scale (my
opinion).)
The other was a new art exhibit. Once, I saw it doing it's dance, but mostly
it just sat there so I wasn't very interested. It was big so you couldn't
see the details.
Tinkerer's Clock
http://www.exploratorium.edu/visit/south-gallery/tinkerers-clock
http://blog.makezine.com/2013/04/15/san-franciscos-new-exploratorium-unveiled/
It didn't have anything to do or poke that I noticed.
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I think the coolest new exhibit is a giant mirror.
http://www.exploratorium.edu/visit/central-gallery/giant-mirror
I can't think of any way to link it to time, so the rest of this is OT. :)
The place closed at 5. We weren't going to make the 5:15 train, so we sat
down and relaxed for a while before heading for the 6:15 train. On the way
out, we stopped by the mirror.
The mirror is 12 ft wide and 8 ft tall, facing you. The focal distance is
about 6 feet. If you are outside the focal distance, everything behind you
is inverted. Your brain adapts quickly. As you step inside that line, your
giant head turns right side up. The background stuff is still upside down.
Your brain locks on to you and flips to normal mode. For me, the place was
closed so nothing in the background was moving and my brain ignored the
background. Then somebody walked by in the way way back. My brain parsed
that as walking on the ceiling. It took a long fraction of a second to
remember all the upside down possibilities and figure out what was going on.
Things like that are the reason I go to the Exploratorium.
Been there - done that. Yes, it is a great place (as I remember it) but
the last time I was there was 40 years ago. . .
Randy, KI6WAS
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