For the Love of Physics (54 page)

telescopes and,
190

wavelength of,
104
,
191

Young, Thomas,
94
–95,
154
,
269

YouTube,
x
,
xii
,
164
,
170
,
225

Z bosons,
18

Zel’dovich, Yakov,
253

zero-gravity environment,
47

Zwicky, Fritz,
197
,
217

ABOUT THE AUTHORS

Walter Lewin
was born and raised in the Netherlands. In 1965 he received his PhD in Physics from the University of Technology in Delft. He arrived at MIT in 1966 as a postdoctoral fellow. That same year he became an assistant professor and in 1974 was made full professor. He is a highly accomplished astrophysicist, a pioneer in X-ray astronomy, and has published more than four hundred and fifty scientific articles. Lewin taught the three physics core classes at MIT for more than thirty years. These lectures were so popular that they were videotaped and became hits on MIT’s OpenCourseWare, YouTube, iTunes U, and Academic Earth. More than a million people from all over the world watch these lectures yearly. Acclaim for his lectures has been featured in many media outlets, including the
New York Times, Boston Globe, International Herald Tribune, Guardian, Washington Post, Newsweek
, and
U.S. News and World Report.
His honors and awards include the NASA Exceptional Scientific Achievement Medal (1978), the Alexander von Humboldt Award, a Guggenheim Fellowship (1984), MIT’s Science Council Prize for Excellence in Undergraduate Teaching (1984), the W. Buechner Prize of the MIT Department of Physics (1988), the NASA Group Achievement Award for the Discovery of the Bursting Pulsar (1997), and the Everett Moore Baker Memorial Award for Excellence in Undergraduate Teaching (2003). He became a corresponding member of the Royal Netherlands Academy of Arts and Sciences and Fellow of the American Physical Society in 1993.

Warren Goldstein
is a professor of history and chair of the History Department at the University of Hartford, where he was the recipient of the James E. and Frances W. Bent Award for Scholarly Creativity (2006). He has a lifelong fascination with physics. A prolific and prizewinning historian, essayist, journalist, and lecturer, his prior books include
Playing for Keeps: A History of Early Baseball
, and the critically acclaimed biography
William Sloane Coffin, Jr.: A Holy Impatience.
His writing about history, education, religion, politics, and sports has appeared in the
New York Times, Washington Post, Chronicle of Higher Education, Boston Globe, Newsday, Chicago Tribune, Philadelphia Inquirer, Nation, Christian Century, Yale Alumni Magazine, Times Literary Supplement
, and
Huffington Post.

*
Be careful—never look at the Sun.

*
It happened to Lise Meitner, who helped discover nuclear fission; Rosalind Franklin, who helped discover the structure of DNA; and to Jocelyn Bell, who discovered pulsars and who should have shared in the 1974 Nobel Prize given to her supervisor, Antony Hewish, for “his decisive role in the discovery of pulsars.”

*
I have assumed here that the force on the charged particle due to gravity is so small that it can be ignored.

*
1 kilogram is about 2.2 pounds.

*
The Royal Society recently posted a digital image of Stukeley’s manuscript online, which you can find here:
http://royalsociety.org/turning-the-pages/
.

*
If you ever want to use this value, make sure that your masses are in kilograms and that the distance,
r
, is in meters. The gravitational force will then be in newtons.

*
If the mass of the string cannot be ignored, and/or if the size of the bob cannot be treated as a point mass, then it is no longer a simple pendulum. We call it a physical pendulum and it behaves differently.

*
Remember, all you scientists, I’m using common rather than technical language here. Even though a kilogram is in fact a unit of mass, not weight, it’s often used for both, and that’s what I’m doing here.

*
If you want to see my photo online, click on the website’s Archive and go to 2004 September 13. See text above for the general URL.

*
If you want to use this equation at home, use 9.8 for
g
and give
h
in meters;
v
is then in meters per second. If
h
is 3 meters (above the floor), the object will hit the floor at about 5.4 meters per second which is about 12 miles per hour.

*
For simplicity I have used 10 meters per second for
g;
we do that often in physics.

*
For rotating black holes the event horizon is oblate—fatter at the equator—not spherical.

*
Little did I know at the time that Jan and I would become very close friends and that we would coauthor about 150 scientific publications before his untimely death in 1999.

*
This acceleration, by the way, is 0.18 percent lower at the equator than at the poles—because Earth is not a perfect sphere. Objects at the equator are about 20 kilometers farther away from the Earth’s center than objects at the poles, so at the equator
g
is lower. The 9.82 is an average value.