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. ---------- 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 ---------- 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? ---------- >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. ---------- 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? :) ----------- 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.) ----------- 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. ----------- 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. -- These are my opinions. I hate spam.

http://jackaperkins.wordpress.com/2010/12/23/the-exploratoriums-harmonic-pen

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. > > ---------- > > 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 > > ---------- > > 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? > > ---------- > > >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. > > ---------- > > 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? :) > > ----------- > > 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.) > > ----------- > > 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. > > ----------- > > 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