The year 2009 was proclaimed by UNESCO and the UN General Assembly as the International Year of Astronomy (IYA 2009). It marked 400 years since Galileo Galilei used in 1609 a telescope invented in Holland, to observe the skies and celestial bodies with previously unprecedented magnifying power. It was an important milestone in the long journey of humankind to the surrounding Universe.
In the endorsement document of the IYA 2009 by UNESCO it is said (quote): “The sky, our common universal legacy, is an integral part of our natural environment, as perceived by humankind. Men have always been watching the skies, trying to understand what is being observed, and find out the physical laws governing the motion of celestial bodies. Our interest, and discoveries, in astronomy have far reaching implications on the development of science, philosophy, religion, culture, and on our perception of the Universe in general”.
It is believed also that the IYA 2009. with the large variety of activities planned worldwide, as well as the IYP 2005, the International Year of Physics proclaimed in 2005 will play an important role in bridging the widening gap between the scientific community and the general public, or to put it more bluntly, the taxpayers, without which the “science train” would simply stop. Contemporary scientific research requires considerable investment, in highly trained manpower, equipment, research labs and institutes. For example, the construction of the Large Hadron Collider (LHC) at CERN will cost the taxpayer 3.2 to 6.4 billion Є. It is thus but natural that the scientific community is becoming more conscious about the importance of deepening the scientific literacy of the people, and promoting science culture to larger communities, especially among the youngsters.
CERN - LHC |
The newly acquired capability, about 400 years ago to observe celestial bodies through the magnifying power of a telescope was no doubt an historical experience for men by creating a kind of a “personal encounter” with the universe surrounding us. However, in the 17
th Century only few could share this experience.
Walking on the Moon |
The next historical event of the kind of a “personal encounter” took place in 1957, with the launch of the first artificial Earth satellite, the Sputnik, which opened the space age. Important milestones during the second half of the 20
th Century were the landing of men on the moon, the Apollo Project, the construction of the International Space Station and the launch of the Hubble Space Telescope in 1990. Hubble continues orbiting the globe at an altitude of 576 km during the last 20 years, providing astronomers and astrophysicists an enormous amount of information (
www.hubblesite.org), which has changed completely their vision of the universe, its beginning and evolution.
Hubble Space Telescope in orbit |
It seems, however, that the most exciting exploration is associated with the recent discovery of extra-solar planetary systems, with planets orbiting around their corresponding stars, presumably, some of them might be earthlike. According to the NASA count, until now 293 stars with planetary systems, and 347 planets were discovered in our galaxy. The drive to discover Earthlike planets in the vastness of our galaxy is intensifying, in eager expectation of the next “historical encounter”, the most important and far reaching, the detection of extraterrestrial life, and may be even distant civilizations.
Detecting Extrasolar Planets by the method of extraction of the planet’s spectral signature |
In the present issue of PhysicaPlus this exciting issue is dealt with by Dan Maoz in an article entitled “Extrasolar Planets, Extraterrestrial Life, and why it Matters”. Hubble’s Deep Space Search gave also an insight into the early Universe, filled with exotic particles after the Big Bang. Particle Physicists all over the world are waiting eagerly for the beginning of orderly operation of the LHC at CERN, which may provide a “mini-simulation” of the Big Bang, and create a “primordial soup” of particles, including the most “wanted”, the Higgs boson, the one which gave mass, the one, to which Eilam Gross is referring to as the “God Particle”, in his article entitled “In Search of the God Particle”.
The missing piece in the puzzle |
Hubble’s Deep Space Search has revealed that the expansion of the Universe is faster than previous predictions. In distant spiral galaxies the rotation speed of stars does not match the predictions according to Newton’s Laws, which brought up the assumption of Dark Matter and Dark Energy comprising about 95% of the total matter. The present status of the Dark Matter issue is summarized by Georg Wolschin in his article “On the Dark Side of the Universe”. However, Moti Milgrom has proposed about 25 year ago another theory explaining the mismatch with Newton’s laws, a Modified Newtonian Dynamics (MOND), which does not require the existence of Dark Matter and Dark Energy to explain the observed phenomena. The article “MOND – Time for a Change of Mind?” by Moti Milgrom sheds light on this issue.
The “Dark Side” of the Universe |
…”Dust to Dust, Ashes to Ashes” – this is how Noah Brosch choose to title his article in this issue. The interstellar space is not really completely empty, it is filled with atoms, gas molecules and solid particles of the cosmic dust. Of special interest is the discovery of relatively large particles, which may cause partial extinction of the light arriving to us from distant galaxies along the whole spectrum of light. This may result in reddening of the light and may be misinterpreted as a Doppler red shift. The discovered properties of interstellar dust may lead to a surprisingly new theory, not involving Dark Matter, to explain the apparently accelerating universe.
A sample of interplanetary dust collected by U2 aircraft at the upper atmosphere |
Avi Loeb and Avery E. Broderick describe in their paper “Shedding Light on Darkness: Imaging Black Hole Silhouettes” a method how to “make Black Holes visible”, or at least to map their silhouettes. It works with the largest Black Hole in the center of our galaxy the Milky Way.
The virtual technician “tests” his cell at the space-time of a Black Hole |
Tsvi Piran tells us the story of the most cataclysmic events in the Universe, in his article entitled “Gamma Ray Bursts, the Strongest Explosions in the Universe”. The discovery of gamma-ray bursts (GRBs) in the 1970ties (by American Vela Satellites, while “chasing” illegal nuclear tests) has started a new branch in astronomy, the Gamma-Ray Astronomy. Monitoring and analyzing GRBs provides a powerful tool to explore “the most fascinating astronomical objects known today” (Tsvi Piron), i.e. marking the death of giant stars, as their core collapses into a Black Hole, and binary neutron star merger, cataclysmic processes releasing unimaginable amounts of energy.
A numerical simulation of the last stage of a binary neutron star merger |
And finally we bring an excerpt from the new book of Mario Livio entitled “Is God a Mathematician?” Like in his first book “The Golden Ratio”, Mario Livio gives a personal expression of his fascination with the power of mathematics.
Alex Manes, Science Editor
Neora (neora.com), Online Editor
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