trillions of possible worlds -- 4/29/20
Today's selection -- from Cosmos: Possible Worlds by Ann Druyan. Gerard Kuiper (1905-1973) is the Dutch scientist viewed as the father of modern astronomy. He did much of his work at the University of Chicago and was advisor to famed astronomer Carl Sagan. The Kuiper belt -- the vast array of frozen objects in the outer solar system -- was named in tribute to him:
"Once there was a boy who had a special power. He could see farther than anyone else when he gazed at the skies. He saw stars too distant and too faint for others to find without a telescope. When most people looked up at the Pleiades they saw the seven sparkling sapphires and perhaps two or three of the dimmer stars. For our ancestors, the Pleiades had served as the qualifying exam for hunters and scouts. If you could see 12 stars, the job was yours. But this boy could see 14. Gerard Peter Kuiper could see stars that were four times dimmer than those visible to the average human eye.
"This was in the Netherlands more than a hundred years ago.
"Back then, the son of a poor tailor could not hope to become an astronomer. But the boy would not be stopped. In that time, astronomers thought that the cosmos consisted of only a handful of planets -- those of our own solar system. Maybe one or two other stars also had planets, they allowed, but our solar system was thought to be one in a trillion. Astronomers saw the great multitude of other stars as barren points of light that had never given birth to any worlds. Even if we weren't the center of the universe, we on Earth could still feel special. Our sun, the scientists believed, was that rarest of stars blessed by worlds and moons.
"Kuiper had a scientist's soul, that yearning to know how the stars and planets had come to be. As a teenager, the young stargazer became fascinated by the ideas of a man who had lived almost three centuries before him: the 17th-century philosopher Rene Descartes. Descartes described his theory of the origin of the solar system, a vision of colorful, swirling pinwheel clouds with the sun at their center. Featureless planets formed out of the spinning clouds. But Descartes lived in one of those times and places where the penalty for advancing an idea that conflicted with the state's religious view could mean imprisonment, torture, death. He kept his vision to himself, and it was only published 20 years after he was safely dead. Descartes's rudimentary conception predated Isaac Newton's understanding of gravity and its role in the formation of the solar system. But it was more than enough to excite the mind of a future scientist.
|Beta Lyrae resolved using the CHARA array|
"Kuiper showed such promise that his father and grandfather pooled their meager resources to buy him a simple telescope. He aced the tests a poor tailor's son was not supposed to pass, and made his way to the University of Leiden in 1924, where a kind of mini-golden age in astronomy was taking place: Willem de Sitter, who collaborated with Einstein on cosmology; Bart Bok, who taught us so much about the evolution and shape of our home galaxy; Jan Oort, who found our sun's place in the galaxy and predicted the existence of the vast cloud of cometary nuclei surrounding our solar system that bears his name; and Ejnar Hertzsprung, who developed the classification system for the stars -- these were just some of the distinguished faculty and students there.
"Leiden was a special place for astronomers at that moment. It may have been the intense ambient light in this densely populated small country and frequently overcast skies that channeled the Dutch away from optical observations and into radio astronomy, which earthly clouds could not obstruct. Radio telescopes harvest the radio emissions from astronomical objects rather than their visible light. Radio astronomy would extend our vision of the cosmos beyond the narrow band of electromagnetic radiation that our eyes have evolved to see.
"Kuiper had rough edges. He was argumentative, and easily drawn into conflict with his colleagues. And he could be careless about properly acknowledging the work of others. His personality quirks would have made life and work in the small pond of Leiden difficult. Kuiper was probably relieved when he was offered an appointment at McDonald Observatory in a corner of West Texas. The prospect of directing a remote observatory, far away from the capitals of scientific culture, must have appealed to him. And besides, you could see the stars better there than just about anywhere else. No cities or towns for miles and miles, just wild darkness.
"At the turn of the 20th century, astronomers had discovered that half the visible stars were really gravitational pairs. Most binary stars are like twins, forming from the same womb of gas and dust. Others come of age separately and become gravitationally involved with each other later in their development. And the other half remain single throughout their lives. Kuiper chose to concentrate on the binary stars. He wondered if they could shed light on the way that the planets of our solar system formed, and came to be gravitationally bound to our sun.
"As with every discovery in the history of science, Kuiper was carrying on the search begun by someone else in another time and place. In this case, it was the work of a scientist of great promise who was only permitted the briefest glimpse of the stars.
"In 1784, a handsome 20-year-old named John Goodricke visited his friend Edward Pigott's observatory in York, England. Goodricke couldn't hear; a childhood illness left him completely deaf. But like Kuiper, he could see things others missed. The telescope Goodricke used was little more than a wooden tube and a mirror, but what it revealed amazed him: There was something funny about a star called Beta Lyrae.
"Goodricke sketched his observations in a log. He continued to observe and sketch Beta Lyrae and its neighboring stars over a period of weeks. ... The Beta Lyrae system is about a thousand light-years from Earth. The largest telescopes of the mid-20th century were just not powerful enough to resolve them as individual stars. We needed the new power of spectroscopy to disentangle them.
"Kuiper imagined how the formation of the contact binary star system could have happened. He envisioned Beta Lyrae's large and small stars spinning backward in time to the period of their formation from a vast, multicolored cloud of gas and dust. He deduced that they were formed when that cloud became so dense that gravitational whirlpools formed. In thinking about these contact binaries, Kuiper couldn't help but wonder if any of these stellar courtships ever failed to catch fire.
Kuiper asked himself: Was our world, our sun, our moon, and all the planets of our solar system nothing more than a failed binary star system? ...
"In 1949, Kuiper astonished the world by declaring that our solar system was not so special after all -- that half of all the stars had their own family of planets.
"A world perhaps?
"How about trillions of possible worlds?
"But science wasn't ready for that universe. It wasn't even ready to take its first baby step off the planet."