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 Artificial Intelligence Helps in the Discovery of New Materials
21.09.2016 | Universität Basel

nachricht Magnetic polaron imaged for the first time
19.09.2016 | Aalto University

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: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

Im Focus: New laser joining technologies at ‘K 2016’ trade fair

Every three years, the plastics industry gathers at K, the international trade fair for plastics and rubber in Düsseldorf. The Fraunhofer Institute for Laser Technology ILT will also be attending again and presenting many innovative technologies, such as for joining plastics and metals using ultrashort pulse lasers. From October 19 to 26, you can find the Fraunhofer ILT at the joint Fraunhofer booth SC01 in Hall 7.

K is the world’s largest trade fair for the plastics and rubber industry. As in previous years, the organizers are expecting 3,000 exhibitors and more than...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

Using mathematical models to understand our brain

16.09.2016 | Event News

 
Latest News

Chains of nanogold – forged with atomic precision

23.09.2016 | Life Sciences

New leukemia treatment offers hope

23.09.2016 | Health and Medicine

Self-assembled nanostructures hit their target

23.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>