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Ebook O Universo Inflacionário: um relato irresistível de uma das maiores idéias cosmológicas do século by Alan Guth read! Book Title: O Universo Inflacionário: um relato irresistível de uma das maiores idéias cosmológicas do século
Date of issue: 1997
ISBN: No data
ISBN 13: No data
The author of the book: Alan Guth
Language: English
Format files: PDF
The size of the: 564 KB
Edition: Campus

Read full description of the books O Universo Inflacionário: um relato irresistível de uma das maiores idéias cosmológicas do século:

[Original review: July 2012]

Yesterday evening, I was sitting with the local knitting group and reading the last few pages of Guth's book. "Should I actually believe this?" I bemusedly asked the two CERN physicists sitting on either side of me. "HELL NO!" said T, after glancing at the cover. "Inflation?? I HATE IT!!! It's why I gave up cosmology and went into nuclear physics! That's real science!" But A had a more positive opinion. "Well," she shrugged, "it's part of the standard Big Bang model. How else are you going to make sense of the observational data?" Then they both hastened to add that I shouldn't take seriously anything they'd said, they weren't experts, not their field. In fact, they didn't know. I wondered if they thought that would be a typical reaction, were I to ask other professional scientists. Would everyone say they didn't know, unless the question concerned the tiny area where they were an acknowledged world-class expert? A thought about it. "Probably," she said. So, ah, to summarise, no one except a handful of experts understands our current theories about the origins of the universe well enough to say whether they make sense, but Alan Guth, the guy who kicked it off, has written a book about how we got here. I personally found it very helpful and feel I grasp the idea of "inflation" far better than I did a week ago: the brief summaries I'd seen elsewhere had left me cold, but seeing how the ideas developed over time put them into perspective and made them less outlandish.

Though I still have real trouble believing this stuff; it seems impossibly speculative, even if it does "explain" important things, in particular the flatness and uniformity of the universe, and the slight unevenness in the Cosmic Microwave Background Radiation (CMBR) that later turned into galaxies. Guth describes his key insight from 1980 and the developments following on from it. You project the history of the universe backwards in time, and it gets hotter and denser the further back you go. At some point, about 10^-35 seconds after the beginning of time, things are so hot that the three non-gravitational forces - electromagnetism, and the strong and weak nuclear forces - all become the same force. But then, winding the clock forwards again, the universe cools down, and they split up into the three forces we see today. In the process of doing so, there could have been an intermediate state, a "false vacuum", where the universe was filled with the enormous energy released by the splitting up of the three forces. This energy would have caused it to expand exponentially, making it uniform and flat; quantum fluctuations would account for the minor unevennesses we have found in the CMBR.

This is indeed the standard story, but I am shocked to see how many assumptions you need in order to make it work. There is a bunch of "Grand Unified Theories" explaining how the three forces can be unified into one, but the energies needed to test them are over a billion times higher than anything we can create in our current accelerators. The potential curve which determines how the energy level falls during the splitting of the forces needs to have a very specific shape in order to get results that match the data. Originally, the idea was that the field mediating the energy was going to be the Higgs field, which we know something about; but in fact the Higgs field turns out not to have the right properties, so a new field was required. (By the way, this seems to be why the Higgs is often called "the God Particle"; people thought for a while that it had created the universe, but they later changed their minds). The universe has to be locally flat enough before inflation started, which involves some kind of theory of quantum gravity. All these theories are speculative.

I can't help being reminded of medieval cosmologies. Back then, astronomers tweaked systems of cycles and epicycles to make them fit the observed notions of the planets. Now, they tweak the potential curves of the inflaton field to make it fit the patterns found in the CMBR. No one had ever seen a crystal sphere, and no one has ever seen an inflaton; perhaps they are equally mythical. But careful analysis of the crystal spheres eventually produced better theories, and I'm guessing the same thing will happen here, given time. Why is there never a Newton around when you need one?
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People who have read this book might want to look carefully at Appendix B and compare it with this paper by J.D. Norton. It certainly seems to me that the 1895 result from Seeliger quoted by Norton completely invalidates Guth's argument, and in fact leaves him looking rather silly. But see if you agree.
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[Update: Aug 17 2014]

Check out Takahiro Terada's one-minute YouTube video Single Superfield Inflation: The Trailer, which I just saw on Sean Carroll's Preposterous Universe blog. It's amazing.

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Ebook O Universo Inflacionário: um relato irresistível de uma das maiores idéias cosmológicas do século read Online! Alan Harvey Guth (born February 27, 1947) is an American theoretical physicist and cosmologist. Guth has researched elementary particle theory (and how particle theory is applicable to the early universe). Currently serving as Victor Weisskopf Professor of Physics at the Massachusetts Institute of Technology, he is the originator of the inflationary universe theory.

He graduated from MIT in 1968 in physics and stayed to receive a master's and a doctorate, also in physics.

As a junior particle physicist, Guth first developed the idea of cosmic inflation in 1979 at Cornell and gave his first seminar on the subject in January 1980. Moving on to Stanford University Guth formally proposed the idea of cosmic inflation in 1981, the idea that the nascent universe passed through a phase of exponential expansion that was driven by a positive vacuum energy density (negative vacuum pressure). The results of the WMAP mission in 2006 made the case for cosmic inflation very compelling. Measurements by the BICEP and Keck Array telescope give support to the idea of cosmic inflation, confirmation of which was given on March 17, 2014, with the findings of the B-mode polarization signature.

In the past Guth has studied lattice gauge theory, magnetic monopoles and instantons, Gott time machines, and a number of other topics in theoretical physics. Much of Guth's current work includes extrapolating density fluctuations arising from various versions of inflation, to test against observations, and investigating inflation in "brane world" models.

Guth is the Victor F. Weisskopf Professor of Physics at the Massachusetts Institute of Technology (MIT). So far, he has written about 60 technical papers related to the effects of inflation and its interactions with particle physics. He has won many awards and medals, including the Medal of the International Center for Theoretical Physics, Trieste, Italy, with Andrei Linde and Paul Steinhardt and the Eddington Medal in 1996, and the 2009 Isaac Newton Medal, awarded by the British Institute of Physics.

In 2005 Guth won the award for the messiest office, organised by the Boston Globe. He was entered by colleagues who hoped it would shame him into tidying up, but Guth is quite proud of the award.

In July 2012, he was an inaugural awardee of the Fundamental Physics Prize, the creation of physicist and internet entrepreneur, Yuri Milner.

More: http://web.mit.edu/physics/people/fac...

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