Importance of Alex V. Filippenko's Work

Early yesterday I listened to Captain Roel Ayala Mata in Sergio Ocampo's program in XEUAG RADIO UNIVERSIDAD DE GUERRERO 840 Khz. AM 1000 W. The University of Guerrero Radio Station here in Chilpancingo.

Here I add to what the Captain said, to put in context the work of the Berkeley Astronomy Professor, that soon will visit us.

In 1998 two scientific groups, the High-Redshift Supernova Search Team (HZT) and the Super Nova Cosmology Project (SCP), discovered that distant exploding stars are more distant than they were expected to be. This implies that the  expansion of the Universe is currently accelerating. Supernovae are searched, because each emits as much light as a whole galaxy in a few days. Astronomy Professor Filippenko was a member of both groups. One of his important contributions was to obtain Keck telescope spectra of the high-redshift supernova candidates, determining whether they are indeed supernovae and measuring their redshift. Both teams reached their conclusions at nearly the same time, although the HZT, where Filippenko stayed after switching from the SCP, announced and published their results first.

I have expressed the opinion that this work deserves the Physics Nobel Prize - by the way this month at Stockholm the Physics Prize will be given for work in fiber optics and CCDs - which greatly aid Astronomy. Here I write my reasons to consider him for that distinction, explaining the importance of the discovery, which Science magazine considered the "Top Science Breakthrough of 1998”.

To begin with: this discovery is a continuation of Edwin Hubble and Allan Sandage's work, both working in California as Alex on the same problem - "The Expansion of the Universe".  At the California Institute of Technology (Caltech) , arguably the most important US scientific institution in Astronomy, where students and faculty collaborate closely with NASA, Alexei V. Filippenko earned his PhD degree in 1984 with Prof. Wallace Sargent. Prior to that he got a BA in Physics from the University of California, Santa Barbara, where I met him as an undergraduate , when I was a graduate student at the Physics Department, since he is close to eleven years younger than I am. He finished there in 1979.

Prof. Filippenko's collaborators developed methods for the use of supernovae as standard candles. If you see how the light goes off, in a few days, you know how much light they sent, thus obtaining the distance between their galaxies and ours.  Alex showed, in the early 1990s, that Type Ia supernovae have a greater spread in their peak luminosities than had previously been assumed, so they could not be used as "standard candles" unless some correction factors were applied. These corrections were later developed and applied by his collaborators. Since the mid-1980s, Filippenko has been studying supernovae at UC Berkeley, and starting in the late-1990s he has used a robotic telescope to find dozens each year. He  is a Professor at his Alma Mater, UC, at the Berkeley campus, near San Francisco, like six hours North by car from Santa Barbara, since California is a huge State. Santa Barbara is almost six hours from the campus in Los Angeles. Caltech is near LA. He is  now the Richard and Rhoda Goldman Distinguished Professor of Astronomy, at U.C. Berkeley.

With hardware and software tools developed by the HZT and SCP groups, at last it was possible to observe the highest number of far supernovae in the History of Mankind. With something like ten of these, with the farthest ever measured at that time, his young collaborator, Adam Riess, born almost ten years after him, finally  found something unexpected. The most distant supernovae were not moving away with the expected velocity. Hubble's law did not apply to them, they were accelerating away from us.

He has many cites of his work by other astronomers. By the way the Mexican Carlos S. Frenk was number 8 in that list. More on him later.

If this was the only contribution Filippenko made, he would deserve the Prize I refer to here. Nevertheless it happens that there are no easy ways to explain this.

Now I write on cosmological theory. What does it mean that the Universe expands?

The first to propose the equations that allow to explain this, was Albert Einstein in 1915.

Here you can see Prof Einstein using the Mt. Wilson 100-inch telescope in California; Edwin Hubble is the one in the middle.

In this visit of Einstein to Hubble, Einstein got convinced the Universe is dynamical, not static as he thought previously. Einstein spent a few days at Caltech, in Pasadena, near Disneyland.

According to the so called General Relativity Theory, the Universe with the known kind of matter before the work of the HZT and SCP, should forever expand at constant velocity or decelerate. It is not possible to accelerate.

To explain this acceleration, the easiest way  in Einstein's Theory of Gravity, is with what he called the Cosmological Constant. Depending on the sign of this constant there could be a repulsive or an attractive effect. We are interested in the repulsive one, since the rest of the Theory already explains gravitational attraction.

Adam Riess' discovery, for which he should get the Nobel Prize, means that we need the Cosmological Constant.

The importance of this discovery is that no known type of matter produces cosmic repulsion. Einstein's Cosmological Constant does not correspond to any known form of matter until now, even less in Einstein and Hubble's time, i.e. last century's 20s.

To end this note I want to introduce a new character in this plot. It is Prof. Carlos S. Frenk.

His brother Julio is very famous in Mexico, since he was Secretary of Health, in the "great" Vicente Fox administration.  Currently Julio is Dean of the Harvard Public Health School, in Boston Massachusetts, and Carlos is the Ogden Professor of Fundamental Physics and Director of the Institute for Computational Cosmology at Durham University and Principal Investigator of the Virgo Consortium. Both studied at UNAM. It seems that UNAM, does not have the capacity to retain some of its stars.

Carlos Frenk then, was one of the first to use supercomputers for cosmological calculations, i.e., of the whole Universe with Einstein's Gravity. With his colleagues in several countries, he demonstrated that it is necessary to have two new types of matter and energy to explain the observations of HZT and SCP . Prior to this supercomputer work, one should recognize Fritz Zwicky in the 1930s , and Vera Rubin in the 1960... and many, many people in the 1980s and 1990s

The names given to these two unknowns are Dark Matter, and Dark Energy. Frenk's result, is that the matter we are made of, which was known up to the great discovery of Universal Acceleration by HZT and SCP, is minimal. This  so-called baryonic matter, in Frenk's soup , is only the salt, something like 4% of the total. Even this small quantity is mainly dispersed as gas all over the known Unvierse. Only 10% of that 4%, is found in the form we know it, mainly stars and black holes, and very little as planets like Earth; by the way over 400 solar systems are known in our Galaxy, the Milky Way.


The great mystery for theoreticians like me, is to find out what is Dark Energy, and for that, I thank my friend Alex, for having given me the opportunity to search for an explanation for Dark Matter and Energy.

Thanks Alex!

P.S. I want to report that the mirror, built under the supervision of Prof. José Luis Pérez Mazariego during the workshop at the Chilpancingo Institute of Technology, was useful already to observe Io - Jupiter's moon - three different days, each time it has been in different positions, since its year is 1.8 terrestrial days.