What's New In The Universe

Conversation : UNIVERSE

What's New In The Universe

Direct Evidence Of Cosmic Inflation
Alan Guth, Andrei Linde [3.17.14]
Introduction by:
Alan Guth, Andrei Linde

 

Alan Guth, a charter member of the Reality Club, came to New York in 1980, to give one of the first Reality Club talks. He presented his new theory on the early universe, which he had been working on for the past couple of years and had described earlier that year in a paper titled "The Inflationary Universe: A Possible Solution to the Horizon and Flatness Problems." It was a revolution in our understanding of the universe—a new theory that filled in the blanks left by earlier versions of the Big Bang theory. A few years later, Andrei Linde developed a version of Guth’s theory he refers to as Eternal Chaotic Inflation, which is now the most popular version of inflation.

Some thirty years later, I'm sitting in a hotel in Vancouver reading the news about what might turn out to be the most important scientific discovery of my lifetime: a possible direct confirmation of Guth's ideas. Using a radio telescope at the South Pole, John M. Kovac and his team of astronomers were able to glimpse the very early universe—capturing traces of light from 13.8 billion years ago. If their data are accurate, Guth was right.

Edge contributor and New York Times deputy science editor Dennis Overbye wrote about the developments in a story on the front page of Tuesday's New York Times: "...Inflation has been the workhorse of cosmology for 35 years, though many, including Dr. Guth, wondered whether it could ever be proved. ... If corroborated, Dr. Kovac’s work will stand as a landmark in science comparable to the recent discovery of dark energy pushing the universe apart, or of the Big Bang itself. It would open vast realms of time and space and energy to science and speculation."

How important is this development? MIT cosmologist Max Tegmark is quoted by Overbye as saying, "I think that if this stays true, it will go down as one of the greatest discoveries in the history of science." According to mathematical physicist Brian Greene, "If the results stand, they are a landmark discovery." Physicist Lawrence Krauss of Arizona State University, in a post on newyorker.com, wrote, "At rare moments in scientific history, a new window on the universe opens up that changes everything. Today was quite possibly such a day."

But nothing is more prescient than Guth's own talks from two Edge Eastover Farm events, in 2001 ("A Golden Age of Cosmology") and 2002 ("The Inflationary Universe"), and Linde's Edge interview in 2012 ("A Balloon Producing Balloons, Producing Balloons: a Big Fractal"). Continue below for EdgeVideo and texts.

—John Brockman

A Golden Age of Cosmology (2001)

Even though cosmology doesn't have that much to do with information, it certainly has a lot to do with revolution and phase transitions. In fact, it is connected to phase transitions in both the literal and the figurative sense of the phrase.

It's often said — and I believe this saying was started by the late David Schramm — that today we are in a golden age of cosmology. That's really true. Cosmology at this present time is undergoing a transition from being a bunch of speculations to being a genuine branch of hard science, where theories can be developed and tested against precise observations. One of the most interesting areas of this is the prediction of the fluctuations, the non-uniformities, in the cosmic background radiation, an area that I've been heavily involved in. We think of this radiation as being the afterglow of the heat of the Big Bang. One of the remarkable features of the radiation is that it's uniform in all directions, to an accuracy of about one part in a hundred thousand, after you subtract the term that's related to the motion of the earth through the background radiation. [Continue]

The Inflationary Universe (2002)

Paul Steinhardt did a very good job of presenting the case for the cyclic universe. I'm going to describe the conventional consensus model upon which he was trying to say that the cyclic model is an improvement. 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. This is more true for the cyclic model, where one has the issue of what happens when branes collide. The cyclic theory could die when that problem finally gets solved definitively. Secondly, there is, of course, the observational comparison of the gravitational wave predictions of the two models.

A brane is short for membrane, a term that comes out of string theories. String theories began purely as theories of strings, but when people began to study their dynamics more carefully, they discovered that for consistency it was not possible to have a theory which only discussed strings. Whereas a string is a one-dimensional object, the theory also had to include the possibility of membranes of various dimensions to make it consistent, which led to the notion of branes in general. The theory that Paul described in particular involves a four-dimensional space plus one time dimension, which he called the bulk. That four-dimensional space was sandwiched between two branes. [Continue]

A Balloon Producing Balloons, Producing Balloons: a Big Fractal (2012)

Let me start by saying that many, many years ago, and I mean like almost a century ago, Einstein came up with something called the "cosmological principle," which says that our universe must be homogenous and uniform. And for many years, people used this principle. In fact, it was formulated even much earlier, by Newton. The universe is still represented this way in current books on astrophysics, where you can find different versions of the cosmological principle.

For a while this was the only way of answering the question, why the universe is everywhere the same. In fact, why it is the universe. So we did not think about the multiverse, we just wanted to explain why the world is so homogenous around us, why it is so big, why there are so many people, why parallel lines do not intercept. Which is, in fact, part of the same question: if the universe was tiny, like a small globe, and you draw parallel lines perpendicular to the equator of the globe, they would intersect at the south and the north poles. Why has nobody ever seen parallel lines intersecting? [Continue]