announcement At 16.30 in Pisa
Milan , February 11, 2016 – 10:26
At 10.50 and 45 seconds (Italian time) on 14 September 2015 the two instruments LIGO experiment in the US (in Washington State and Louisiana) have recorded an unusual thing. once the confirmations to be sure they are started. And at 16.30 in Pisa (a few minutes before the twin press conference in Washington) the official announcement of the discovery of gravitational waves. For physics and science throughout the February 11, 2016 will be a date that will have a separate chapter in the textbooks. Gravitational waves, in fact, exactly a century ago have been planned, in November 1915, when Albert Einstein spoke on his theory of general relativity, which constitute one of the cornerstones. But until now you had never been “found” and the ad can aspire to the title of the “discovery of the century.” And the researchers who participated in the experiments come from the candidates in one of the next Nobel Prize in physics. In this collective enterprise collaborated 1,004 researchers from 133 scientific institutions around the world.
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gravitational waves: what are they and how were discovered
and Einstein’s gravitational waves
The observation
Revealed gravitational waves have been produced in the last split second of the merger process of two blacks holes, the mass equivalent to about 29 and 36 solar masses, in a single rotating black hole more massive than about 62 solar masses: the three missing solar masses to the total sum equivalent to the energy emitted during the fusion process of the two blacks holes, in the form of gravitational waves. The two holes blacks, before merging path have a spiral path and then collide at a speed of about 150 thousand kilometers per second, half the speed of light. The observation also confirms the existence of binary systems of blacks holes of stellar mass, in particular having a greater mass of 25 solar masses. The merger process of the two holes blacks in charge of revealed gravitational waves is an event that happened to 410 megaparsec from us, and then goes back nearly a half billion years ago.
” A milestone “
” This result represents a milestone in the history of physics, but even more is the beginning of a new chapter for astrophysics, “said Fulvio Ricci, professor at the University of Rome La Sapienza researcher of coordinating the international Virgo collaboration . “To observe the universe through the gravitational waves radically changes our ability to study it: so far it is as if we had looked through x-rays, but now we can do the ultrasound of our universe.” “At last we can see the universe in a different way,” he added Astone Pia, INFN researcher in the writing scientific article about the discovery with five other colleagues from LIGO and Virgo published on Phisycs Reviews Letters . “It is no coincidence, in fact, that the first direct measurement of amplitude and phase of gravitational waves has been accompanied by another important discovery, that the merger of a binary system holes blacks.”
shadow carousel
LIGO and Virgo experiments have discovered gravitational waves
What are
Gravitational waves are like ripples the fabric of space-time that permeates the entire universe. According to Einstein gravity itself it is due to the curvature of space-time caused by the mass. Gravitational waves are produced by the movement of bodies with mass in space-time. More events are colossal and emit extraordinary amount of energy, such as the Big Bang itself, the clash between two blacks holes, the “dance” of rapprochement of two neutron stars that rotate rapidly (pulsar), the greater the magnitude of gravitational waves and then – in theory – it is easier picking them up. Only that so far with the tools at our disposal it proved virtually impossible to decipher them because we ourselves and the tools we are immersed in our turn in space-time, and we are involved from its oscillations.
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Einstein’s general theory of relativity is 100 years old
The special theory of relativity
Why are they important
The discovery of gravitational waves is not just (yet another) experimental confirmation of the validity of Einstein’s theory, but it revolutionizes and expands the world of physics and cosmology. For example, until now the study of the cosmos has been realized only through the signals emitted by stars and galaxies in the electromagnetic spectrum (visible light, X-rays and gamma rays, infrared, ultraviolet, radio waves of various wavelengths). The existence of gravitational waves opens up a new world: the ability to study the universe (and the mysterious blacks holes) in a completely different way. In addition to “see,” we will also be able to “hear” in its most basic essence, the space-time, two items that, according to Einstein, are one. And to understand how and why the universe not only expands, but is actually accelerating its expansion rate. And there are those who assume that border on science fiction scenarios: verifying the existence of wormholes ( wormhole in English) in the vicinity of blacks holes that could be related or distant parts of the universe even different universes from ours. Finally arrive at the solution of the basic components of the space-time according to the theory of quantum mechanics, still divided between “string”, “branes” or “rings” ( loop ). “This result is a special gift for the one hundredth anniversary of general relativity,” concluded Fernando Ferroni, president of the INFN. “It’s the final seal on a wonderful theory that has left us the genius of Einstein and is also a finding that rewards the group of scientists who pursued this research for decades to which Italy has contributed a lot.
The announcement
the LIGO observatories recorded the arrival of gravitational waves on 14 September with a duration interference just 10 thousandths of a second. The discovery in fact also speaks Italian. Researchers at the National Institute of Nuclear Physics (INFN) have taken part in the experiment and the INFN organizes a press conference in Pisa at the European Gravitational Observatory laboratories (Ego), where he also Virgo, the Italian experiment that has worked with his American counterpart (Ligo). In Washington at the National Press Club announcement it is organized by the National Science Foundation, the Massachusetts Institute of Technology (MIT) and the Laser Interferometer Gravitational Wave Observatory (LIGO). In addition the magazine Phisycs Reviews Letters has published a scientific study on the subject.
How did it come to” capture “gravitational waves
If, as has been said, you are immersed in spacetime, as we have been able to pick up gravitational waves? The two experiments (Ligo and Virgo) are in practice two enormous long tubes each direction 4 and 3 km willing to L, that is perpendicular to one another. In each of these tubes there is a laser beam that is reflected fifty time by particular mirrors so as to lengthen the path. If a gravitational wave passes, it expands the space in one direction (one of the tubes) and it shortens in the direction orthogonal to the first (for a length of billionths of billionths of billionths of a meter). Stretching space, the laser light then takes longer to cross one of the two arms of Virgo or Ligo, while it employs less in orthogonal arm where space is restricted. Analyzing with extreme precision the advance times and delay (and eliminating any type of noise), it is possible to pick up the gravitational wave. Easy to say, those who succeed in the enterprise takes home the Nobel.
February 11, 2016 (amendment 11 February 2016 | 20:20)
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