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Stephen Hawking's Universe

Episode 1 : Seeing Is Believing

From the dawn of civilization, humans have struggled to understand the nature of the universe. The ancients sought answers from pure reason limited by beliefs in gods and an earth-centered universe. Eratosthenes’s determination of the earth’s radius and Ptolemy’s system of planetary motion shed no light on more fundamental issues. In the Renaissance, Copernicus, Kepler, Galileo, and Newton sparked a revolution in thought. They added measurement and the concept of universal physical law to reason and supposition. Science was born, initiating discoveries which, in 1927, brought Edwin Hubble to a California mountaintop observatory with the right question and the means to answer it. The interpretation of his results was astounding: the entire universe was expanding from an explosive moment of creation — the big bang.

Episode 2 : The Big Bang

Many scientists of the early 20th century, including Albert Einstein, found the idea of an expanding universe with an abrupt origin unpalatable. They viewed the universe as static and eternal. Ironically, the most vocal advocate of the expanding universe was Father LaMaitre of the Roman Catholic Church, the institution that had once strenuously resisted Galileo’s ideas. Were the same human constraints that plagued earlier astronomers present in modern times? To a certain extent they were, but now there was a difference. All scientists agreed that the controversy could only be settled by direct and precise measurements. What measurements? For almost 40 years a debate raged until Robert Dicke proposed that the big bang would have produced a flash of light still present everywhere as a glow of radio waves. In 1965 Arno Penzias and Robert Wilson unmistakably found that glow, now called the Cosmic Microwave Background Radiation (CMBR). The debate was over. Our universe, the totality of all things, had a fiery beginning about 15 billion years ago.

Episode 3 : Cosmic Alchemy

What is the universe and everything in it made of? Where does it all come from, and how do we know? Discoveries in the late 19th century revealed that the entire observable universe is made of the same elements as those on earth. With knowledge of the dual nature of matter and energy, scientists began to fit the pieces of the macroscopic and microscopic world together. This program covers the discovery of the nature of matter, its initial creation from the primordial conditions in the big bang, the building up of elements in stars, and the way this might affect the end of the universe.

Episode 4 : On The Dark Side

According to the observational research of Vera Rubin on the velocities of stars around galaxies, there is a great deal of matter exerting a gravitational force that we simply cannot see. This matter appears to be of an entirely different nature from the ordinary matter we experience, observe, and interact with in everyday life. There is no spectral evidence of its presence. This “dark matter” makes up roughly 90 percent of the stuff in the universe, and it has important gravitational implications for the future of the universe. Specifically, will the universe keep expanding forever, or will it someday stop and start collapsing upon itself on the way to a big crunch? Perhaps there is just enough matter for the expansion to be halted by gravity, but not enough to collapse. For science there are two problems here: What is the mysterious dark matter? How much of it is there?

Episode 5 : Black Holes & Beyond

The universe is a strange and violent place, full of regions spewing out energy on an unimaginable scale and objects so massive not even light can escape from them. With the discovery of quasars (extremely luminous, compact objects in the hearts of ancient galaxies), the picture of the universe became more complex. Though the mechanism responsible for such enormous outputs of energy is not completely established, one answer was found in a part of Einstein’s theory of relativity — black holes, specifically supermassive black holes at the centers of distant galaxies. These objects consume enormous amounts of matter. As the matter falls inward, it releases a large amount of observable energy. Einstein didn’t think black holes were possible, despite the fact that his own theory implied their existence. Robert Oppenheimer thought otherwise and set out to prove the presence of collapsed stars so massive not even light can escape them. Black holes seem to be a reality.

Episode 6 : An Answer To Everything

Scientists generally agree on the big bang origin of the universe as we see it today. Fifteen billion years ago there was a momentous event whose nature is uncertain. But as we track the expansion backward, toward that moment of seeming creation, the details blur. Is our universe a minor event in an endless series of universes (or multiverses)? Our physics seem inadequate to explain the early times in a way that is consistent with the conditions existing today. That is a crucial requirement of science — no gaps should exist in the cause-and-effect chain linking two moments in a physical history. If our physics fails, understanding on the most fundamental level weakens; we have a crisis in science. New tentative and remarkable theories uniting relativity and quantum mechanics have been proposed — inflation theory and superstring theory. They are strange, not yet worked out, but seem to shed light on the earliest times. They hold the promise of providing a simple and elegant way to explain everything in universe and how it all works.