Einstein's Explanation of Brownian Motion

One of Fowler's Physics Applets

This Java applet is a simple demonstration of Einstein's explanation for Brownian Motion. It shows little particles batting about a more massive one and what it would look like if you could see only the massive one through a microscope.

Author:Drew Dolgert
Owner and contact:Michael Fowler - mfowler@virginia.edu
Date:22 September 1998
Distribution:Gnu Public License, How to link to the applet
Language:Java 1.1

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This applet is in Java 1.1. Earlier browsers, even early versions of Java 1.1, may not display this applet. Comments and translations welcome. I apologize if I've failed to translate "Start," "Stop," and "Reset."

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Also available on our FTP Site.


language - the two-letter language code
EN for English, FR for French, etc. This is the first specifier of a Locale. While some languages like Russian aren't official Default Locales, we can certainly add them if someone supplies an appropriate properties file. If you do not specify a language, the applet should use the default language specified by your browser's Java Virtual Machine.

country - the two-letter country code
CN for China, IT for Italy. This further specifies a locale if, for instance, you want to differentiate French in France, "FR", from French in Canada, "FR_CA".

threadsleep - integer, defaults to 40
The number of milliseconds the Piston thread should pause after it shows the next frame of a shot. Set higher for smooth animation on slow machines, lower for even smoother animation on fast machines.

nballs - integer, defaults to 40
The number of red balls.

massratio - double, defaults to 20
The ratio of the mass of the blue ball to that of the red balls.

averagevelocity - double, defaults to 5
The average velocity of the red balls. The units are pixels moved/redraw.

magnification - double, defaults to 10
The microscope view is a magnified version of the atomic view. This sets the ratio.

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