Albert Einstein 311.
(photo credit: Al. Aumuller / Library of Congress)
Nearly a century after Albert Einstein wrote about gravitational waves – small
ripples in the fabric of space-time considered to be the “sounds” of the
universe – scientists are still searching for them. Advanced gravitational wave
detectors are being built in the US, Europe, Japan and Australia, and are
scheduled to become operational in 2015. But the task is daunting; there are
competing sources of “noise” that make it difficult to establish the source of
any wave detected.
As a result, astronomers have for a long time been
seeking a potential electromagnetic “marker” signal appearing with or after some
gravitational waves. Such a marker would make it possible to verify the
connection between detected gravitational waves and specific astronomical
In their new article published recently in Nature
, Prof. Tsvi
Piran of the Hebrew University of Jerusalem and Dr. Ehud Nakar from Tel Aviv
University wrote that they had actually managed to identify such a
marker. Nakar and Piran noted in their article that an unidentified
transient radio signal observed in 1987 by Dr. Jeffrey Bower and colleagues has
all the characteristics of such signal, and thus may in fact have been the first
direct detection of a neutron binary star merger in this way.
noticed that surrounding interstellar material would slow debris ejected at
velocities close to the speed of light during the merger of two neutron stars.
Heat generated during this process would be radiated away as radio waves. The
resulting strong radio flare would last a few months and be detectable with
current radio telescopes from a billion light years away.
moving mass produces gravitational waves, a signal loud enough to be detected
requires the motion of huge masses at extreme velocities. The prime candidate
sources are mergers of two neutron stars – two bodies, each with a mass
comparable to the mass of our sun. Such events are thought to take place only
once in hundreds of thousands of years per galaxy. Thus to detect a signal
within our lifetime, the detectors must be sensitive enough to detect signals
out to distances of a billion light years away from Earth. This poses an immense
technological challenge. At such distances, the gravitational wave signal would
sound like a faint knock on our door when the TV set is turned on and the phone
Search after such a radio signal would certainly take place
following a future detection, or even a tentative detection of gravitational
waves. However, even before the advanced gravitational wave detectors become
operational, as expected in 2015, radio astronomers are prepared to look for
these unique flares.TEACHING TEACHERS SCIENCE
teachers have completed advanced studies in the Rothschild-Weizmann Program for
Excellence in Science Teaching and will be awarded M.Sc. degrees in science
teaching from the Weizmann Institute’s Feinberg Graduate School in Rehovot. This
program – the first of its kind in Israel – is designed for high-school science
teachers. In the upcoming year, about 100 will be enrolled in the two-year
It is based on the belief that the best way to improve science
education is to train excellent teachers. Thus, the Rothschild-Weizmann Program
invites top science teachers to participate. In cooperation with Weizmann
Institute scientists, an intensive study program was put together in which the
students deepen their knowledge in all fields of science, meet with scientists
and visit their labs, learn about the latest scientific advances, gain new
approaches to teaching, participate in institute research on science education
and have the opportunity to lead new educational initiatives.
Rothschild-Weizmann Program, supported by the Caesarea Edmond Benjamin de
Rothschild Foundation, was established three years ago. Heading the program are
Prof. Shimon Levit of the faculty of physics and Prof. Bat Sheva Eylon, head of
the science teaching department.
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