A world-renowned theoretical physicist and professor at the Massachusetts Institute of Technology, Guth is best known for pioneering the theory of cosmic inflation, a model that explains the exponential growth of the universe mere fractions of a second after the Big Bang, and its continued expansion today. Cosmic inflation not only describes the underlying physics of the Big Bang, however. Guth believes it also supports the idea that our universe is one of many, with even more universes yet to form. Science Friday headed to MIT where this writer also works, but in a different department to chat with Guth in his office about the infinite possibilities in an unending cosmos, and the fortune cookie that changed his life.
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Related Topics What is the Inflation Theory? The Inflation Theory proposes a period of extremely rapid exponential expansion of the universe during its first few moments.
It was developed around to explain several puzzles with the standard Big Bang theory, in which the universe expands relatively gradually throughout its history. Limitations of the Big Bang Theory While the Big Bang theory successfully explains the "blackbody spectrum" of the cosmic microwave background radiation and the origin of the light elements , it has three significant problems: The Flatness Problem: WMAP has determined the geometry of the universe to be nearly flat.
However, under Big Bang cosmology, curvature grows with time. A universe as flat as we see it today would require an extreme fine-tuning of conditions in the past, which would be an unbelievable coincidence.
The Horizon Problem: Distant regions of space in opposite directions of the sky are so far apart that, assuming standard Big Bang expansion, they could never have been in causal contact with each other. This is because the light travel time between them exceeds the age of the universe. Yet the uniformity of the cosmic microwave background temperature tells us that these regions must have been in contact with each other in the past.
The Monopole Problem: Big Bang cosmology predicts that a very large number of heavy, stable "magnetic monopoles" should have been produced in the early universe. However, magnetic monopoles have never been observed, so if they exist at all, they are much more rare than the Big Bang theory predicts.
It proposes a period of extremely rapid exponential expansion of the universe prior to the more gradual Big Bang expansion, during which time the energy density of the universe was dominated by a cosmological constant -type of vacuum energy that later decayed to produce the matter and radiation that fill the universe today. Inflation was both rapid, and strong.
Inflation is now considered an extension of the Big Bang theory since it explains the above puzzles so well, while retaining the basic paradigm of a homogeneous expanding universe. Moreover, Inflation Theory links important ideas in modern physics, such as symmetry breaking and phase transitions, to cosmology. How Does Inflation Solve these Problems? The Flatness Problem: Imagine living on the surface of a soccer ball a 2-dimensional world.
It might be obvious to you that this surface was curved and that you were living in a closed universe. However, if that ball expanded to the size of the Earth, it would appear flat to you, even though it is still a sphere on larger scales. Now imagine increasing the size of that ball to astronomical scales.
To you, it would appear to be flat as far as you could see, even though it might have been very curved to start with. Inflation stretches any initial curvature of the 3-dimensional universe to near flatness. The Horizon Problem: Since Inflation supposes a burst of exponential expansion in the early universe, it follows that distant regions were actually much closer together prior to Inflation than they would have been with only standard Big Bang expansion. Thus, such regions could have been in causal contact prior to Inflation and could have attained a uniform temperature.
The Monopole Problem: Inflation allows for magnetic monopoles to exist as long as they were produced prior to the period of inflation. During inflation, the density of monopoles drops exponentially, so their abundance drops to undetectable levels. As a bonus, Inflation also explains the origin of structure in the universe.
Prior to inflation, the portion of the universe we can observe today was microscopic, and quantum fluctuation in the density of matter on these microscopic scales expanded to astronomical scales during Inflation.
Over the next several hundred million years, the higher density regions condensed into stars, galaxies, and clusters of galaxies. Further Reading:.
His early childhood was unremarkable, although he showed a strong aptitude for mathematics. After attending several public schools, he skipped his senior year to enrol in a five-year program at the Massachusetts Institute of Technology MIT , partly because he was concerned about being drafted for the Vietnam War, of which he strongly disapproved. In , he married his high school sweetheart, Susan Tisch, and they were to have two children: Lawrence and Jennifer However, after graduating, Guth had a hard time finding a permanent job, partly because of the intense competition for university professor positions due to the baby boom, and he spent nine years traveling across the country pursuing temporary post-doctorate jobs related to physics, including time spent at Princeton to , Columbia to , Cornell to and at the Linear Accelerator Center at Stanford to
THE INFLATIONARY UNIVERSE
The shortcoming that inflation is intended to fill in is the basic fact that although the Big Bang theory is called the Big Bang theory it is, in fact, not really a theory of a bang at all; it never was. I agree with what Paul said at the end of his talk about comparing these two models; it is yet to be seen which one works. But there are two grounds for comparing them. One is that in both cases the theory needs to be better developed.
What is the Inflation Theory?
The fate of the universe depended on its density. If the density of the universe was large enough, it would collapse into a singularity , and if the actual density of the matter in the cosmos was lower than the critical density, the universe would increasingly get much bigger. The GUT explained all the fundamental forces known in science except for gravity. It established that in very hot conditions, such as those after the Big Bang, electromagnetism, the strong nuclear force, and the weak nuclear force were united to form one force. Weinberg also was the one who emphasized the idea that the universe goes through phase transitions, similar to the phases of matter, when going from high energy to low energy.