January 17, 2022

The Big Bang and Beyond: Exploring the Early Universe | Free Courses – Gyaan24.com

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Description

We live in a golden age of cosmology, which is the science that deals with the origin and development of the universe. It was only a century ago that Edwin Hubble showed that there are galaxies outside of our own Milky Way—trillions of them, as we now know. A few years later, he discovered that most of these galaxies are moving away from each other in an expanding universe. Then roughly 60 years ago, that expansion was proved to have begun in a moment of incredibly high density and temperature that scientists have labeled as the Big Bang. The breakthroughs have continued since then with amazing insights, such as these:

  • Dark Matter. This abundant but invisible substance was responsible for the collection of gas into protogalaxies tens of millions of years after the Big Bang. Dark matter far outweighs ordinary matter in the universe, and its existence was only confirmed in the 1970s.
  • Inflation. For a fraction of a second after the Big Bang, the universe may have undergone a period of runaway growth, inflating to unimaginable size. Developed in the 1980s and supported by many observations, inflation theory explains baffling features of our universe.
  • Dark Energy. In the 1990s, cosmologists discovered that galaxies are moving away from each other ever-faster over time, suggesting that something is exerting a repulsive force pushing all the galaxies outward. This mysterious expansive influence has been termed “dark energy.”

As remarkable as it may seem, researchers have assembled a detailed description of events that occurred 13.8 billion years ago, when the universe as we know it got its start. The Big Bang and Beyond: Exploring the Early Universe tells this breathtaking story in 12 half-hour lectures for nonscientists, presented by award-winning educator Gary Felder, Professor of Physics at Smith College.

Professor Felder takes you from the Big Bang to the formation of the first elements and the condensation of the earliest stars. Covering settled science as well as bold but, as of yet, unproven speculations, The Big Bang and Beyond will change the way you think about the starry heavens, and even reality itself. Relying on minimal mathematics, Professor Felder employs innovative graphics and analogies to convey truly awe-inspiring ideas.

The Amazing Picture So Far

One of Professor Felder’s goals in the first lecture of this course is to dispel common misconceptions about the Big Bang. Contrary to popular belief, the Big Bang model is not a theory of how the universe began. Instead, this model explains how the universe has evolved since the earliest moment that the known laws of physics can describe—an instant 13.8 billions years ago when the universe was extraordinarily hot and dense, but not infinitely so. He then spends the first part of the course covering well-established concepts about the early universe, including:

  • Planck Density. This is the start of the Big Bang, when each atomic-nucleus sized region of the infant universe had the equivalent of a billion galaxies of mass, and the temperature in Celsius was 1 with 32 zeroes after it. The density and temperature fell rapidly as the universe expanded.
  • Cosmic Microwave Background. This is the “smoking gun” proof of the Big Bang—the faint microwave radiation that pervades all of space and was created at the moment when atoms first formed. It was emitted almost 13.8 billion years ago and has been speeding towards us from all directions ever since.
  • Observable Universe. Because light travels at a finite speed, there are regions of the universe so far away that no light from them has had time to reach us since the Big Bang. We don’t know what’s beyond the part of the universe we can see, or even whether or not the universe goes on forever.

Open Questions and Startling Ideas

In the second part of the course, Professor Felder focuses on more open questions and conjectural ideas, discussing competing theories and weighing the evidence for and against them. Here, you deal with some of the most exciting unsolved problems in cosmology.

For example, you will explore what may have happened before the Big Bang. Scientists can’t yet say what happened before the universe was at Planck density, but they’re working on it. Solving this mystery requires reconciling inconsistencies between quantum mechanics and Einstein’s general theory of relativity, which governs gravity.

You will also consider whether or not there are extra dimensions. One of the most powerful ideas for uniting gravity and quantum mechanics is string theory, which calls for extra spatial dimensions beyond the three that we experience in our universe. If that’s true, then the fact that we see three dimensions must be a result of processes that took place just after the Big Bang. Similarly, you dive into the possibility of the multiverse. The fact that our universe appears to be fine-tuned for life makes sense if it is just one of many universes with markedly different random properties. Naturally, we live in the one that makes our existence possible! This is just one of many reasons for believing in the multiverse.

Professor Felder closes the course with an exploration of the most promising areas of experimental research for resolving these and other questions about the early universe. Such projects, many of which are now underway, include better telescopes, improved measurements of the cosmic microwave background, the search for gravitational waves generated after the Big Bang, and new initiatives in particle physics. As a working cosmologist, Professor Felder has definite views about the best way forward. But he also believes in the importance of an open mind and serendipity, for as you learn in The Big Bang and Beyond, some of the key breakthroughs in understanding the origin and development of the universe have come from out of the blue—or rather, from out of this world.

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