Einstein Science Reporting for Kids
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3-Sep-2004

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American Association for the Advancement of Science

Precious glass? Why life wouldn't be the same without it



A scientist looks at a glass beaker.
Click here for a high resolution photograph.

Glass may not cost as much as gold, but considering how it has changed human history, it's as precious as any fancy metal. Without glass there would have been no cameras, no thermometers, and no eyeglasses -- to name just a few things that are good to have around.

Alan Macfarlane of the University of Cambridge in Cambridge, U.K., is a man who really appreciates glass. He and his colleague, Gerry Martin, wrote an essay appearing in the 03 September 2004 issue of the journal Science about how much glass has changed our lives over time.



A glass eye dropper and test tubes.
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According to the ancient Romans, traders accidentally discovered glass as they cooked over campfires on the beach. Apparently they noticed that a clear liquid formed when hot objects near the campfire melted and mixed with sand. (People many years earlier may also have discovered how to make glass by melting sand.)

Glass has added beauty to our lives ever since, and it has had important practical uses too. Glass windows let light into people's homes. Glass lanterns let travelers find their way on rainy nights. And glass panes painted on one side with silver allowed people to see their reflections.

What really impressed Macfarlane and Martin is how important glass has been to scientific research. For one thing, you need glass to make lenses. Lenses show up in everything from microscopes, for studying bacteria and other really small things, to telescopes, for studying faraway objects like stars and planets.



Glass petri dishes.
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Simply being able to hold substances in clear containers was crucial for scientists. For example, in order to read a barometer, which measures pressure, you need to see how high a liquid has risen inside a clear container.

Barometers were one of the instruments that allowed researchers to study the behavior of gasses. Without these discoveries, there would have been no steam engine and no electricity, according to Macfarlane and Martin.

When the two authors considered 20 famous scientific experiments that changed our world, they found that 15 of them couldn't have happened without glass tools.

Fortunately, although glass has been critical for improving human lives and knowledge, it isn't as expensive as "precious" metals or gems. It's much too easy to break!

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