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Professor Barry Barish Was Awarded a “Doctor honoris causa “Degree by Sofia University

At an official ceremony in Aula magna of the Rectorate, Professor Barry Barish of California Institute of Technology was awarded a “Doctor honoris causa” honorary degree by Sofia University “St. Kliment Ohridski”.

The proposal for the award with the honorary title of the oldest and most prestigious high academic institution in this country came from the Faculty of Physics and is for the substantial contribution of Professor Barry Barish in the setting and conducting of a laser experiment for registering gravitational waves. In 2017 Professor Barish was awarded the Nobel Prize for physics for his exceptional achievements in reaching unprecedented precision in the interferometric measurements which brought to the registering of gravitational waves.


The ceremony was opened by the Dean of the Faculty of Physics Professor Dr habil Alexander Draishu who briefly presented Professor Barish’s CV.

Professor Barry Barish was born in 1936 in Omaha, Nebraska, USA. In 1957 he graduated with a B. Sc. in Physics, and in 1962 he defended his Ph D at the University of California in Berkeley. He began his career as a research worker in Berkeley (1962-1963) and then as a researcher at California Institute of Technology where he has been spending the rest of his career. In 2005 he was elected a Professor Emeritus.


Professor Barish embarked on his scientific career in the domain of physics of the high energies. He worked on experiments with a linear accelerator at Stanford. In 1980 he was included in the search for magnetic monopolies – a hypothetic elementary particle which is an isolated magnet with one pole. Professor Barish was in charge of a project team working on an experiment of a superconducting super collider, a gigantic accelerator of elementary particles in Texas but in 1993 US Congress cancelled the project.


Since 1994 Professor Barish has been the main researcher in the LIGO (Laser Interferometer Gravitational-Wave Observatory) Project. In the period 1992-1993 the US National Scientific Fund (NSF) showed grave concerns related to its practical implementation and management structure. Professor Barish was at the base of serious organizational and technological changes of the LIGO design, as, for example, the use of solid body lasers which are more powerful that the initially planned argon gas lasers. On the LIGO Project he worked in close cooperation with the California Institute of Technology and the Massachusetts Institute of Technology.

In the process of his work Professor Barish came to realize that to reach the goals of the LIGO Project it was necessary to have a constant team of experts in various domains of science and the technologies and wide international cooperation. In 1997 Professor Barish became the LIGO Director and it was under his supervision that the LIGO SCIENTIFIC COOPERATION was set up – a team of hundreds of scholars from all over the world.


On September,14th, 2015 the updated version of the Advanced LIGO system registered for the first time gravitational waves generated by the merging of a pair of black holes, 1.3 billion light years away from us.


Professor Barry Barish was awarded with the title of “doctor honoris causa” of Sofia University by Alma mater’s Rector Professor Dr habil Anastas Gerdzhikov. The honorary Doctor thanked for the honour, expressed his joy of being in Bulgaria and noted the exceptionally warm hospitality he was given.


Professor Barry Barish delivered an academic speech on the topic: “Einstein, the Black Holes and Gravitational Waves“ which dwelt on the work of his team aiming at a better understanding of the Universe through fundamental research in physics.

He pointed out that today we have a better understanding of nature due to the fundamental discoveries in physics, astronomy and cosmology. Einstein’s idea that there are gravitational waves, similar to the ocean and electromagnetic waves, dates back to 1915-1916, i.e. a hundred years later it was proved valid.

Modern science has taken a different route, Professor Barish stressed and added that the greatest discoveries during the recent years were not conducted in the standard laboratory way. Science has evolved into big collaborations with huge experimental equipment and we still do not know what we are about to discover with our modern technologies, resources and laboratories. Professor Barish added that due to the big teams bringing many people with various skills together, today we can answer questions which were never answered before and he gave an example with the Nobel Prize for Physics of the past few years.

In his lecture Professor Barish talked about gravitational waves in order to explain more comprehensively the discovery made by his team: “In a way our history started 1.3 billion years ago. 1.3 billion years ago there were two black holes which clashed and merged. It took 1.3 billion years with the speed of light that that information reached the Earth exactly at the time when we had constructed a big apparatus capable of detecting gravitational waves”.

He pointed out that in 1915 Einstein created a new concept of gravitation which replaced Newton’s theory. However, this does not mean that Newton’s theory was wrong; it was simply incomplete. And this took place with the combination and connection of space and time, Professor Barish pointed out.


One year after the creation of the new theory of gravitation Einstein predicted the existence of gravitational waves in a small article, written in German in 1916. Professor Barish remarked that Einstein did not believe that the latter would ever be discovered not because they were not valid but rather because, in 1915, he could not imagine the modern technologies we are in possession of today.

In his lecture Professor Barry Barish also talked about the black holes, defining the latter as an area in space where gravitation is so strong that nothing can escape from it: “In Einstein’s theory even light cannot escape from it. They are real. A black hole forms when a star emits light through a process known as nuclear synthesis. While this synthesis is burning, it exhausts the fuel of the star – first the light elements, then the heavier ones and, finally, when it is out of fuel, gravitation contracts the star and it collapses. We call this a “supernova” – it is formed when the star has run out of fuel and it collapses – a similar thing will happen to our Sun some day“.

In his words, when this collapse takes place, the nuclear matter is closed off in very small space and that creates strong gravitation. If gravitation is strong enough, that creates a black hole. It turns out that our Sun is too small and it cannot become a black hole. But if a star is heavier, for example, three times more than the Sun, when the former collapses, it will turn into a black hole.

Together with his team, they have found that the black holes can exist in pairs, revolving around each other, exactly as the Moon revolves around the Earth and the Earth around the Sun.


“What we witnessed took place 1.3 billion years ago and came to Earth three years ago: two black holes, each with a mass about 30 times greater that the Sun. This is 10 million times bigger than the Earth’s mass. They have collapsed in a certain way from a star to a size not very much different from the size of Sofia. When we saw them the two were at a distance less than Sofia – Bucarest from each other, revolving around each other at a speed equaling half the speed of light,” Professor Barish said. He added that during the revolution they emitted radiation and ultimately merged into an object which is a bigger black hole. All that happened 1.3 billion years ago – at the time when the transition from monocellular to multicellular organisms was taking place on Earth.

“In the process of merging the black holes emit gravitational waves. When these waves reach Earth, they distort space and that is the thing we are trying to measure with a huge instrument, called inferometer. We measure these waves up to a tenth of the second with the help of two such inferometers in the states of Washington and Louisiana, which are 3 000 km away from each other“.

That was the signal that Professor Barish and his team saw on the morning of September, 14th, 2015, with the two inferometers. Einstein’s theory yields an analogous result of what the scholars have observed and the results are described far more precisely: “That convinced us that we have really discovered gravitational waves. That is the beginning of something very big. Indeed, the gravitational waves exist and that is why the Nobel Prize was awarded. That was, in fact, the beginning of a new science. Hundreds of years will pass till it gets sufficiently developed“.

Soon after its first discovery Professor Barish’s team made a new one – the merging of two completely different objects – a pair of neutron stars. The black holes do not emit any other radiation that can be registered by the telescopes. The neutron stars, however, emit radiation that can be registered – photons, gamma-rays, etc. The merging of the two neutron stars which we observed was registered two seconds later by satellites, the latter registering gamma-rays from the same direction in the sky, Professor Barish remarked. He added that then it was the first time that only gravitational waves of an astronomical object had been observed, and it was done with the other astronomical instruments. “Once breaking that piece of news to the astronomers, more than 4000 telescopes – half of all the existing telescopes on Earth – aimed at that point in the sky. We say that we already have multiinstrumental astronomy which can register not only electromagnetic radiation but also gravitational waves and neutrino. That event of merging of two neutron stars was studied extensively during the past year”, Professor Barish remarked.


He talked at length about a mystery that has been puzzling the physicists for a long time – the existence of heavy chemical elements.. Where do gold and platinum come from and how did they appear on Earth when the latter was still being formed? The greater part of the Universe was formed by hydrogen and helium. When a star burns all of its fuel and collapses, heavy elements are formed. When it runs out of fuel, it also burns all its elements – from hydrogen to iron. We know that in the periodical system there are elements beyond iron and we can synthesize them in our laboratories. How did gold and platinum appear in the periodical system? They have not been formed under normal conditions in the stars. The extreme processes of merging of the neutron stars give an answer to that puzzle. Thus, the hypothesis, that the formation of heavy elements in the merging of neutron stars which we observed last year for the first time, can be considered a validated hypothesis, Professor Barry Barish stated.

“Thus starts the development of a new science. I would like to draw an analogy with Galileo. In 1608 for the first time Galileo used something different from the human eye – lenses with which he constructed a telescope. He observed Jupiter and found 4 satellites. That was the beginning of modern astronomy. Now, 400 years later, with much more powerful telescopes, we have learnt much more about the Universe“, Professor Barish pointed out and added that now we have other ways and means of observing the Universe – by means of the gravitational waves. Thus we can witness events that are impossible to be observed with electromagnetic waves. For example, it is the first time we have been observing the merge of black holes and the merge of neutron stars. That is the beginning of a possibility to see much more of the Universe than we do now. And it is likely to take another 400 years till we come to understand fully the Universe. This is only the beginning, Professor Barry Barish said.