The force of gravity rules the universe. It governs our everyday lives on Earth and it controls the motions of the heavens above. Yet it is one of the least understood of all the forces of nature. To endeavor to understand this fundamental force is to experience anew something as simple as getting out of bed, throwing a ball, or diving into a pool; and it gives deep insight into the central organizing principle of the cosmos.
When we consider ourselves, not as static beings fixed in time but as dynamic, ever-changing creatures, our viewpoint of human history becomes different and captivating.
Many students struggle in high school chemistry. Even if they succeed in earning a good grade, they often still feel confused and unconfident. Why is this? And what can be done to help every student succeed in this vitally important course? Success in chemistry, according to veteran science teacher Professor Frank Cardulla, doesn’t require any special intellectual gifts or talents or advanced mathematical skill. All it requires is a genuine understanding of the ideas that students encounter in the high school chemistry classroom. If students truly understand what they are learning, they will do more than just succeed in high school chemistry; they will find lasting success as they continue to study chemistry in college and beyond.
On a dark, clear night, a magnificent band of hazy light arches overhead that ancient Greeks likened to a trail of milk spilled across the sky. It is the Milky Way, the galaxy where we live, seen edge-on from our vantage point on the inside. There are countless stars at all stages of stellar life, vast clouds of interstellar gas and dust, star clusters, and even satellite galaxies, but no close-up view can match that of the Hubble Space Telescope, which has been surveying the wonders of the Milky Way for three decades.
A few hundred miles above Earth, there is a remarkable telescope with a crystal-clear view across the universe. For two decades, the Hubble Space Telescope has been amassing discoveries that rival those of history’s greatest scientists and explorers, making it the most important and productive scientific instrument ever built.
Every plant, microorganism, and animal on Earth exists within an ecosystem: a complex network of interdependent relationships in which each individual strand is important and contributes to the success of the whole. Ecosystems, in turn, interact with one another to form the biosphere: the zone of life on our planet.
Everyone appreciates a well-designed bridge, a sturdy skyscraper, or a flightworthy aircraft. But how many of us who aren’t engineers think, “I could build that”? In fact, you can. You may not have a professional engineer’s credentials, but you can tinker all you want in your own workshop, using readily available materials to build working models that solve all the fundamental problems of the real thing.
There’s more to the universe than meets the eye—a lot more. In recent years, scientists have discovered that 95% of the contents of the cosmos are invisible to our current methods of direct detection. Yet something is holding galaxies and galaxy clusters together, and something else is causing space to fly apart.
One of the triumphs of modern science has been our ever-improving understanding of how life works—how chemical reactions at the cellular level account for respiration, digestion, reproduction, locomotion, and a host of other living processes. This exciting subject is biochemistry—and its allied field of molecular biology. In the past century, progress in these complementary disciplines has been astonishing, and a week rarely passes without major advances in medicine, physiology, genetics, nutrition, agriculture, or other areas, where biochemistry and molecular biology are shedding new light on life.
For the first time in human history, we can see the full splendor and mystery of the universe, thanks to instruments on scores of planetary probes and observatories that have been launched into space since the 1990s.
Life is stranger than fiction. Recent investigations hint at episodes in the history of life on Earth that rival the most imaginative movies. For example: Could our planet have been seeded with life from elsewhere? Did the development of life create conditions that threatened to poison the biosphere? How have natural forces conspired, over and over, to remove most traces of life from the planet? And how has life itself responded with determination to survive and thrive in a multitude of astonishing forms?
In May 1905, an unknown 26-year-old Swiss patent clerk wrote to a friend about four scientific papers he had been working on in his spare time. He casually alluded to one as “revolutionary,” and he confidently asserted that another would modify the “theory of space and time.” He had not yet started on a fifth paper that would also come out in 1905 and that would propose a surprising and earth-shaking equation, E=mc2.