Archive for Gruber Prize

The 2019 Gruber Prize for Cosmology: Nick Kaiser and Joe Silk

Posted in The Universe and Stuff with tags , , , , , , , on May 9, 2019 by telescoper

I’ve just heard that the Gruber Foundation has announced the winners of this year’s Gruber Prize for cosmology, namely Nick Kaiser and Joe Silk. Worthy winners the both of them! Congratulations!

Here’s some text taken from the press release:

The recipients of the 2019 prize are Nicholas Kaiser and Joseph Silk, both of whom have made seminal contributions to the theory of cosmological structure formation and to the creation of new probes of dark matter. Though they have worked mostly independently of each other, the two theorists’ results are complementary in these major areas, and have transformed modern cosmology — not once but twice.

The two recipients will share the $500,000 award, and each will be presented with a gold medal at a ceremony that will take place on 28 June at the CosmoGold conference at the Institut d’Astrophysique de Paris in France.

The physicists’ independent contributions to the theory of cosmological structure formation have been instrumental in building a more complete picture of how the early Universe evolved into the Universe as astronomers observe it today. In 1967 and 1968, Silk predicted that density fluctuations below a critical size in the Cosmic Microwave Background, the remnant radiation “echoing” the Big Bang, would have dissipated. This phenomenon, later verified by increasingly high precision measurements of the CMB, is now called “Silk Damping”.

In the meantime, ongoing observations of the large-scale structure of the Universe, which evolved from the larger CMB fluctuations, were subject to conflicting interpretations. In a series of papers beginning in 1984, Kaiser helped to resolve these debates by providing statistical tools that would allow astronomers to separate “noise” from data, reducing ambiguity in the observations.

Kaiser’s statistical methodology was also influential in dark matter research; the DEFW collaboration (Marc Davis, George Efstathiou, Carlos Frenk, and Simon D. M. White) utilised it to determine the distribution and velocity of dark matter in the Universe, and discovered its non-relativistic nature (moving at a velocity not approaching the speed of light). Furthermore, Kaiser devised an additional statistical methodology to detect dark matter distribution through weak lensing — an effect by which foreground matter distorts the light of background galaxies, providing a measure of the mass of both. Today weak lensing is among cosmology’s most prevalent tools.

Silk has also been impactful in dark matter research, having proposed in 1984 a method of investigating dark matter particles by exploring the possibilities of their self-annihilations into particles that we can identify (photons, positrons and antiprotons). This strategy continues to drive research worldwide.

Both Kaiser and Silk are currently affiliated with institutions in Paris, Kaiser as a professor at the École Normale Supérieure, and Silk as an emeritus professor and a research scientist at the Institut d’Astrophysique de Paris (in addition to a one-quarter appointment at The John Hopkins University). Among their numerous significant contributions to their field, their work on the CMB and dark matter has truly revolutionised our understanding of the Universe.

I haven’t worked directly with either Nick Kaiser or Joe Silk but both had an enormous influence on me, especially early on in my career. When I was doing my PhD, Nick was in Cambridge and Joe was in Berkeley. In fact I think Nick was the first person ever to ask me a question during a conference talk – which terrified the hell out of me because I didn’t know him except by scientific reputation and didn’t realize what a nice guy he is! Anyway his 1984 paper on cluster correlations was the direct motivation for my very first publication (in 1986).

I don’t suppose either will be reading this but heartiest congratulations to both, and if they follow my advice they won’t spend all the money in the same shop!

P.S. Both Nick and Joe are so distinguished that each has appeared in my Astronomy Lookalikes gallery (here and here).

Planck wins the Gruber Prize (and the Shaw Prize)

Posted in Science Politics, The Universe and Stuff with tags , , on May 13, 2018 by telescoper

I forgot to mention last week that the 2018 Gruber Prize for Cosmology has been awarded to the Planck team, and its Principal Investigators Nazzareno Mandolesi and Jean-Loup Puget.

For more information about the award and the citation, see here.

This annual prize is worth $500,00; the two PIs will get $125,000 each and the rest divided among the team. I’m not sure whether this means the Planck Science Team (whose membership is listed here or the entire Planck Collaboration (which numbers several hundred people) but regardless of whoever gets the actual dosh, this award provides a good excuse to send congratulations to everyone who worked on this brilliant and highly successful mission!


UPDATE: 14th May 2018. Jean-Loup Puget has also been awarded the Shaw Prize for Astronomy.

2013 Gruber Prize in Cosmology

Posted in The Universe and Stuff with tags , , , on July 11, 2013 by telescoper

The latest session at this Summer School began with a nice announcement, that one of the organizers (and lecturers) Viatcheslav Mukhanov has, together with Alexei Starobinsky, been awarded the prestigious Gruber Prize for cosmology.

The press release linked above states:

According to the Prize citation, their theoretical work “changed our views on the origin of our universe and on the mechanism of its formation of structure.” Thanks to their contributions, scientists have provided a compelling solution to two of the essential questions of cosmology:  Why is the structure of the universe so uniform on the largest scales?  Where did the departures from uniformity—such as galaxies, planets, and people—come from?

Mukhanov, full professor of physics at the Ludwig-Maximilians-Universität in Munich, and Starobinsky, the main research scientist at the Landau Institute for Theoretical Physics in Moscow, will share the $500,000 award, which will be presented on September 3 as part of the COSMO2013 conference at the Stephen Hawking Centre for Theoretical Cosmology in Cambridge, UK.

The work for which they are being honored began in the late 1970s and early 1980s, during a period of fertile, even fervid, theoretical investigations into the earliest moments of the universe.  In 1965 astronomers had discovered the cosmic microwave background—relic radiation dating to an era 13.8 billion years ago, when the universe was approximately 380,000 years old, during which hydrogen atoms and photons (packets of light) decoupled, causing a kind of “flashbulb” image that pervades the universe to this day.  This discovery validated a key prediction of the Big Bang theory and inspired a generation of theorists.

Among them was Starobinsky, then a senior research scientist at the Landau Institute.  His approach was to use quantum mechanics and general relativity to try to address how an expanding universe might have originated.  While he did not resolve that issue, his calculations made in 1979 – 1980 did indicate that the universe could have gone through an extraordinarily rapid exponential expansion in the first moments of its existence.

The following year Mukhanov (Moscow Physical-Technical Institute) and G. V. Chibisov (Lebedev Physical Institute, Moscow; he passed away several years ago), began working on the implications of quantum fluctuations within the Starobinsky model.  Quantum fluctuations—disturbances in the fabric of space predicted by Heisenberg’s uncertainty principle—are always present in the universe.  But in an extremely small, extremely dense, and extremely energetic newborn universe they would have had an outsized presence.  What’s more, the kind of exponential expansion that Starobinsky was proposing would have stretched those fluctuations beyond the quantum scale.  In 1981 Mukhanov and Chibisov discovered that these fluctuations could play the role of the seeds that eventually bloomed into the present large-scale web-like structure of the universe:  galaxies, clusters of galaxies, and superclusters of galaxies.

When this mechanism was first proposed, it looked like a piece of science fiction. Indeed, usually quantum fluctuations appear only on tiny subatomic scales, so the idea that galaxies have been born from quantum fluctuations seemed totally outlandish. And yet the subsequent developments in theoretical and observational cosmology strongly favored this possibility.

Shortly after the Starobinsky work, the American physicist Alan Guth proposed a brilliant idea that an exponential expansion stage of the early universe, which he called “inflation,” could explain the incredible uniformity of our universe and resolve many other outstanding problems of the Big Bang cosmology. However, Guth immediately recognized that his proposal had a flaw: the world described by his scenario would become either empty or very non-uniform at the end of inflation. This problem was solved by Andrei Linde, who introduced several major modifications of inflationary theory, such as “new inflation” (later also developed by Albrecht and Steinhardt), “chaotic inflation”, and “eternal chaotic inflation.” A new cosmological paradigm was born. In 2004, Guth and Linde received the Gruber Prize for the development of inflationary theory.

The original goals of the Starobinsky model were quite different from the goals of inflationary theory. Instead of trying to explain the uniformity of the universe, he assumed that the universe was absolutely homogeneous from the very beginning. However, it was soon realized that the mathematical structure of his model was very similar to that of new inflation, and therefore it naturally merged into the rapidly growing field of inflationary cosmology.

In 1982, several scientists, including Starobinsky, outlined a theory of quantum fluctuations generated in new inflation. This theory was very similar to the theory developed by Mukhanov and Chibisov in the context of the Starobinsky model. Investigation of inflationary fluctuations culminated in 1985in work by Mukhanov, who developed a rigorous theory of these fluctuations applicable to a broad class of inflationary models, including new and chaotic inflation.

This theory predicted that inflationary perturbations have nearly equal amplitude on all length scales. An equally important conclusion was that this scale invariance is close, but not exact: the amplitude of the fluctuations should slightly grow with the distance. These fluctuations would have equal amplitudes for all forms of matter and energy (called adiabatic fluctuations). The theory also predicted a specific statistical form of the fluctuations, known as Gaussian statistics.

Since then, increasingly precise observations of the cosmic microwave background radiation (CMB) have provided decisive matches for theoretical predictions of how those initial quantum fluctuations would look after the universe had been expanding for 380,000 years.  Those observations include all-sky maps produced by the Cosmic Microwave Background Explorer (COBE), the Wilkinson Microwave Anisotropy Probe (WMAP), and the Planck satellite.  John Mather and the COBE team received the Gruber Cosmology Prize in 2006; Charles Bennett and the WMAP team received theirs in 2012.

Back in 1979, Starobinsky also found that exponential expansion of the universe should produce gravitational waves — a quantum by-product of general relativity, and a target for the new generation of instruments expected over the next decade.

This year’s Gruber Cosmology Prize citation credits Starobinsky and Mukhanov with a profound contribution to inflationary cosmology and the theory of the inflationary perturbations of the metric of space-time. This theory, explaining the quantum origin of the structure of our universe, is one of the most spectacular manifestations of the laws of quantum mechanics on cosmologically large scales.

Congratulations to them both! Sadly, Slava Mukhanov left Bad Honnef yesterday evening in order to return to Munich so he’s unable to use a small part of his share of the $500,000 prize to buy celebratory drinks for all the participants, but I’m sure we’ll have some sort of  celebration in his absence. But that will have to wait until this evening. We wouldn’t want to interrupt the lectures, would we?