Connect the Dots: A Museum Educator Designs a Special Tour for Your Next Visit
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November 05, 2009
Mike Alexander, director of visitor programs, knows a thing or two about the Museum — he's been here for over 30 years! So he was happy to design an Exhibit Halls tour for our visitors. Follow Mike as he connects the dots between our Museum exhibits and some of the key scientific discoveries that led to our current understanding of physics and chemistry.
The Big Bang
"Everything around us — people, peanut-butter-and-jelly sandwiches, and rock — is obviously made of different substances," says Mike. But where did these substances come from? How did it all begin? Astronomers theorize that billions of years ago, all matter was concentrated in a small dense area until a massive explosion — the Big Bang — created the expanding universe.
For the first stop on your walking tour, visit the exhibit Welcome to the Universe (Red Wing, Level 1) to share the experience of astronomical discovery through hands-on activities, 3-D models, and historic artifacts. Then, travel to the farthest reaches of our universe — and back to the beginning of it all — by heading next door to the Planetarium to catch a viewing of Journey to the Edge of Space and Time.
View the Elements
Next, head to Natural Mysteries (Blue Wing, Lower Level) to learn how matter is classified. Look for the "Periodic Table of the Elements," which puts these most basic of all substances into neat columns based on how they behave in chemical reactions.
This handy science tool has been around since 1869, when Dmitri Mendeleev first formally classified our chemical building blocks, atoms. Scientists guessed that similar chemical behaviors of the atoms might be caused by even smaller particles inside the atoms. But how could they study things so impossibly small? Walk next door to the "Cloud Chamber" in Take a Closer Look (Blue Wing, Lower Level) to find out!
Create a Cloud
The "Cloud Chamber," which looks like a squat aquarium, holds gas that is saturated with a liquid. Scottish physicist Charles Wilson was inspired to invent it in 1895 after observing light effects on a foggy mountain peak. "All it takes is the tiniest bit of extra energy to form a cloud," Alexander explains.
In 1911, by using cloud chambers, scientists were able to determine that atoms are made up of different arrangements of smaller, subatomic particles. Introduce, say, the nucleus of a helium atom, and liquid condenses around the particle, leaving behind tracks. "It's like watching the contrail of a jet in the sky," Mike says. "You can see the length and shape of the cloud, but not the plane — or particle — itself." Electrons, for example, make thin zigzag cloud trails, while the nuclei of helium atoms make broad ones. Scientists were able to identify the properties of the particles based on the appearance of these trails.
An Electrifying Finale
See particles in action at your final stop, the Theater of Electricity (Blue Wing, Level 2). What are those two towering metal spheres? They are part of the world's largest Van de Graaff generator, which is also known as an "atom smasher" or "particle accelerator." Three long rubber belts run up and down inside one of the support columns at 40 miles per hour, carrying electrically charged particles to the spheres, where the particles spread out, resulting in the powerful electric sparks you can see during one of the Museum's live Electricity! or Lightning! shows.
Originally the two spheres in this generator were separate; one sphere had a positive charge and the other, negative. Scientists accelerated the particles between the two spheres until they were going so fast that they could smash apart the nucleus of an atom to reveal the smaller particles — protons and neutrons — inside. Researchers later used even more powerful accelerators to determine that protons and neutrons themselves are made of something even smaller: quarks.
Keep Connecting
In one day at the Museum, you can embark on a scientific odyssey that explores the universe's basic building materials: from matter and elements to atoms and quarks. "As you move from the 'Periodic Table' to the 'Cloud Chamber' to the Theater of Electricity," says our tour guide, "you go deeper into the atom — and deeper into our understanding of what makes up the world around us."
This article appears in the August - September 2009 issue of Sparks!, a newsletter for members and friends of the Museum.
