Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Beyond ’pi in the sky’

03.04.2003


Andrei Linde lauds the new era of precision cosmology



For most of us, "inflation" is a term that comes up only in conversations about the economy or flat tires. But for many cosmologists, inflation is the ultimate word in understanding how the universe was created.

In the beginning, according to inflation theory, the universe was tinier than an atom. Then, in an unimaginably brief period of time - .00000000000000000000000000000001 second, to be precise - it expanded ("inflated") to a size trillions of times bigger than what we can observe today.


A handful of scientists in the United States and the former Soviet Union independently came up with the idea of inflationary cosmology in the late ’70s and early ’80s - among them, Russian cosmologist Andrei Linde, now a professor of physics at Stanford; former SLAC researcher Alan Guth, now at the Massachusetts Institute of Technology; Paul Steinhardt, now at Princeton University; and Andreas Albrecht, now at the University of California-Davis.

WMAP experiment

When first proposed more than two decades ago, the inflation hypothesis was considered somewhat exotic, but subsequent experiments have provided a wealth of data verifying many of its underlying principles.

In February, scientists announced the results of the latest cosmological experiment - a NASA satellite called the Wilkinson Microwave Anisotropy Probe (WMAP). Launched in 2001, WMAP captures light waves that were produced during the Big Bang some 13.7 billion years ago. NASA scientists used the light wave data to create a detailed map of the universe that confirms many aspects of inflationary theory while ruling out others.

Cosmic conference

The WMAP experiment was a featured topic of discussion during a conference on cosmic inflation at UC-Davis in March - a three-day event attended by many leading cosmologists including Albrecht, Guth, Linde, Steinhardt and Stephen Hawking of Cambridge University. Researchers presented new findings on a wide range of hotly debated cosmological issues, including string theory - the idea that the universe was built from infinitesimally small string-like particles; multiverses - Linde’s hypothesis that our universe is but one of many interconnected universes that inflate and contract like so many soap bubbles; and the cyclic model - Steinhardt’s competing proposal, which states that there is one universe that undergoes an endless sequence of cosmic epochs that always begin with a "bang" and end with a "crunch."

While conference participants clashed over specific theories, they were unanimous in their praise for the WMAP experiment and what physicists call the new era of precision cosmology, in which speculation about the nature of the universe is confirmed or rejected by solid experimental data.

During a break at the conference, Linde discussed some of the latest trends in cosmology with Stanford Report science writer Mark Shwartz.

Q: How did the results of the WMAP experiment affect cosmic inflation theory?

A: WMAP makes a big leap in confirming many of the predictions of inflationary cosmology, and this places the theory on much firmer ground that it was before.

When inflationary theory was first proposed about 20 years ago, nobody really expected that in our lifetime we would have any serious tools developed to verify whether we were right or wrong. Of course, we knew all the way that we were right, because the theory was beautiful! But it’s one thing to have moral assurance that you’re doing a decent thing, and another thing to see that your predictions are confirmed experimentally.

At today’s conference there was a competing scenario - I would not really call it a theory - the cyclic model of the universe. This is a very exotic model, although it has some chance to work.

Q: Is the idea that the universe recycles over and over?

A: Yes, but the idea that the universe may go in cycles is actually a very old idea. There are many people who have studied an oscillating model of the universe. The problem is that all of them have failed to describe what happens at the moment that the universe collapses. How exactly does it start expanding again?

Many statements made by the authors of the cyclic scenario during the last two years were quite controversial, and some of them were simply incorrect. Also, they do postulate the stage of inflation before the collapse of the universe. Therefore, from my perspective, the cyclic model is just an extremely complicated and, I would say, baroque version of inflationary cosmology.

Q: It seems like string theory also took a few hits at this conference from Stephen Hawking and others.

A: Well, since 1985, string theorists were telling us, "We really know how to do things. We’re going to explain our world soon." This may be right - string theory is very powerful; but it is also immensely complicated - and it changes every two years.

One of the main challenges to string theory has been cosmology. If string theory is unable to explain the present acceleration of the universe, it will be too bad. If string theory is unable to explain inflation, it will be too bad - unless we find some alternative mechanism explaining where the galaxies came from and why our universe is so large and homogenous. So string theory has come under scrutiny and attack by some people.

However, I do not think that there is any reason to be pessimistic with respect to string theory and its relation to cosmology. Just a month ago, physicists Shamit Kachru, Renata Kallosh [both of Stanford], Sandip Trivedi [of India] and I found a way to describe the present acceleration of the universe in string theory. The next challenge is to find a good mechanism describing inflation in string theory. This is a very complicated problem, but I think that it is solvable. In fact, we are working on it now.

Q: Did WMAP throw out some of your own theories or cause you to change them in any way?

A: If an experiment is good, then it not only confirms something but it also rules out something. WMAP tends to rule out one of my lovely theories - I have many! However, a much simpler version of the same theory is quite fine and doing quite well.

So one thing WMAP is capable of is ruling out some theories, leaving alive some others - and that’s wonderful, because in this way, we can really sort out many different versions of the same theory and pick out one that agrees with the observational data better.

But so far, if you ask me, I do not really know of a class of theory that I would consider as a decent competitor of inflation at the moment.


###
By Mark Shwartz

CONTACT: Mark Shwartz, News Service: 650-723-9296, mshwartz@stanford.edu

COMMENT: Andrei Linde, Physics: 650-494-6106, alinde@stanford.edu

Mark Shwartz | EurekAlert!
Further information:
http://map.gsfc.nasa.gov
http://physics.stanford.edu/linde/
http://superstringtheory.com/index.html

More articles from Physics and Astronomy:

nachricht Extremely fine measurements of motion in orbiting supermassive black holes
28.06.2017 | Stanford University

nachricht Ultra-compact phase modulators based on graphene plasmons
27.06.2017 | ICFO-The Institute of Photonic Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Extensive Funding for Research on Chromatin, Adrenal Gland, and Cancer Therapy

28.06.2017 | Awards Funding

Predicting eruptions using satellites and math

28.06.2017 | Earth Sciences

Extremely fine measurements of motion in orbiting supermassive black holes

28.06.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>