This timeline A Century of Physics originated in a committee formed in 1995 to plan the celebration of the 100th birthday of the American Physical Society. The committee's chair, Brian Schwartz, who was charged by the APS with the responsibility for producing the timeline, hired the creative team, found sponsors, and provided continued support for the project. In 1996 Sidney Perkowitz assembled a database of more than a thousand scientific events from which he chose about 130 for grouping into story-lines. He wrote a draft of the text while designer Albert Gregory planned the organization of the timeline into a series of posters. In 1997 Hans von Baeyer revised and completed the text, as Gregory continued to perfect the design. Images were located with the help of Patricia Rabine, Liz Carver, the staff of the Niels Bohr Library of the American Institute of Physics, and the Clarendon Foundation. In 1998 Darlene Logan assisted in the campaign to secure sponsors. For two years, as the timeline evolved through increasingly elaborate versions, members of the APS, teachers, and students contributed suggestions. With color separations by Lasergraphics, the W. E. Andrews company printed the posters in time for the APS centennial celebrated in March 1999.

• Brian B. Schwartz is Vice President for Research and Professor of Physics at The Graduate Center of the City University of New York
• Albert Gregory is a designer in Boston.
• Sidney Perkowitz is Charles Howard Candler, Professor of Physics at Emory University.
• Hans C. von Baeyer is a Chancellor Professor of Physics at the College of William and Mary.

Following the story-lines in A Century of Physics
The story of physics in the 20th century unfolds like a splendid tapestry teeming with people, ideas, and things. In order to find patterns in this tangle, it helps to pick out five color-coded story-lines that stretch like broad, horizontal ribbons from beginning to end.

		tells the story of the quest to understand the universe of galaxies and stars embedded in spacetime. Its dimensions are incomprehensible distances, such as the 1022 meters that separate us from our neighboring Andromeda Galaxy.
		Closer at hand, the Human scale refers to the more familiar distances from the global to the microscopic that are immediately accessible to our senses.
		In the foreground, the Atomic scale focuses on the submicroscopic world of atoms and quarks - down to the unimaginable 10-15 meter radius of a proton.
The Cosmic, Human, and Atomic scales correspond to separate branches of physics. Up until 1900, classical physics dealt mostly with phenomena on the human scale, but for a description of the cosmic and atomic realms, new mathematical languages had to be developed. The three story-lines remained fairly distinct until the 1960s, when they finally began to converge in a synthesis that represents one of the great triumphs of modern physics.
		illustrates how physics is related to biology and medicine.
		traces the application of scientific discoveries to devices and techniques that help to shape everyday life.
Occasionally, when an event belongs properly to more than one of these five story-lines, it is coded with more than one color.

The references to Art woven into the bottom border serve as reminders that science is but one of many different perspectives on the world.

As physics probes beyond the human scale of comprehensible dimensions, it encounters progressively larger and smaller numbers. In cosmic and atomic physics, numbers with ten, twenty, or even forty digits, either before or after the decimal point, are common. In order to avoid the awkwardness and tedium of writing out such monstrosities, and to reduce the chance of error, scientists -- and this timeline - employ the elegant, compact Exponential Notation. Here are a few examples:

1 000 000 000 000 = 10¹² a trillion (in American usage)
1 000 000 000 = 10⁹ a billion (in American usage)
1 000 000 = 10⁶ a million
1 000 = 10³ a thousand
1 = 10⁰ one
0.001 = 10^-3 a thousandth
0.000 001 = 10^-6 a millionth
0.000 000 001 = 10^-9 a billionth (in American usage)
0.000 000 000 001 = 10^-12 a trillionth (in American usage)

Alfred Nobel's Legacy
In 1896 Alfred Nobel, a Swedish industrialist who had grown super-rich by inventing dynamite and developing it into a universal tool for both beneficial and belligerent purposes, died at the age of 63. To the chagrin of his heirs, he left the bulk of his fortune to an endowment for funding yearly prizes in physics, chemistry, medicine or physiology, literature and the promotion of peace. He could scarcely have foreseen the profound effect his legacy would have on the cultural life of the twentieth century.

In physics, the Nobel prize has become the supreme standard of personal achievement. No other award comes close to matching its prestige in the minds of the public or the scientific community. Out of the multitude of scientific inventions and discoveries this century has brought forth, the Nobel prize has selected a small handful for distinction as brightly shining beacons of excellence.

To be sure, many worthy contributions to science, and many brilliant scientists, go unrewarded. Increasingly, for example, experiments in physics require the collaboration of large teams whose work is as essential as it is unheralded. On the other hand, an occasional Nobel award may be undeserved. Inevitably politics, power, connections, fashion and just plain luck affect the selections. The Nobel prize is, after all, a human institution, and hence fallible, but in the end it is without a doubt the highest honor a physicist can aspire to. Without the generous and deeply felt respect, not to say affection, of the physics community for its laureates, the competition for the Nobel prize would have lost its dignity long ago and degenerated into a mere popularity contest. The fact that it remains as prestigious in 1999 as it was in 1901 when Wilhelm Conrad Röntgen earned the first physics prize for the discovery of X rays, is a testament to Alfred Nobel's wisdom. Even dynamite appears feeble compared to the power of the Nobel prize to inspire curious minds.