Montshire Minute: Cool Moves

Originally aired during the week of March 8, 2004

Monday

Debate raged in the late 1800's over this question: Does a galloping horse have all four legs off the ground at any one time? Former California Governor Leland Stanford argued that it did. To prove it, he enlisted the help of photographer Eadweard Muybridge. Motion picture cameras had not been invented, so Muybridge placed several cameras around the track and attached trip wires to them. A running horse activated the cameras, resulting in a series of photographs recording the animal's motion. These photographs have been incorporated in a zootrope (a simple device that shows still images in rapid succession, simulating a motion picture). Thanks to a new visiting exhibit called Cool Moves: The Artistry of Motion, there are many hands-on exhibits at the Montshire related to the science of how things move and change. See it beginning March 13!

Tuesday

We tend to think of rhythm as something that relates to sound, especially music. But when you think about it, we are surrounded by many rhythms that we can see, as well as hear. On yesterday's program we made note of Eadward Muybridge's series of photographs of a running horse. His experiment represented the beginning of motion pictures. Movies can be thought of as rhythms you can see - a series of rapidly moving still pictures lit by a lamp. Your eye and brain collaborate to make the images seem like they are actually moving seamlessly. This happens because the initial image stays in the retina and is retained by the brain, blending with the next image to make it seem as though the pictures move. This process is called persistence of vision.

Wednesday

We've been talking about persistence of vision, the process that makes movies (really a series of still pictures) appear to actually "move." Strobelights, lights that blink on and off very rapidly, also can change our perception of movement. If a cylinder moves at the same rate the strobelight is blinking, the cylinder will appear to be motionless. Strobelights are useful in revealing rhythms too fast for the eye alone to notice. Scientist Harold Edgerton used the strobe to examine movements like balloons popping, or drops falling. Printing press operators can use strobelights to read newspapers that are moving rapidly on the presses. Common fluorescent lights in our homes or offices flash at 60 hertz (or cycles per second), a rate so fast we can't perceive a flicker.

Thursday

The change of seasons is one natural rhythm that is very evident in our part of the country at any time of year. But there are lots of natural movements that take place over such a long period of time that we will never experience the changes in our lifetimes. Take the precession, or slight wobbling of the earth's motion. While the earth makes a complete rotation roughly every 24 hours, it also wobbles on its axis very slightly, like a spinning top that's slightly imbalanced. As a result, the North Pole traces a circle that takes 25,000 years to complete. Because of this motion, the position of the north star in our sky is always changing. Right now, Polaris is our north star, because it's closest to the north pole. In about 12,000 years, another star, Vega, will be designated as the north star.

Friday

Throw a rock in a quiet pool, and waves appear on the surface of the water. Strike a tuning fork, and sound waves spread out in all directions. Light a match, and waves of light similarly expand in all directions - at the incredible speed of 300,000 kilometers per second. Come to think of it, most information about our surroundings come to us in some form of wave. All types of waves are similar in that they cannot exist in one place, but must extend from one place to another. And, all waves require vibration - for sound it can be the vibration of a guitar string, for light, vibration of electrons in an atom. You can catch a lot waves with Cool Moves: The Artistry of Motion, a new traveling exhibit at Montshire that explores many rhythms and movements found in nature.