Onde gravitazionali:arriva la conferma definitiva della loro esistenza / Gravitational waves:the definitive confirmation of their existence arrives
Segnalato dal Dott. Giuseppe Cotellessa / Reported by Dr. Giuseppe Cotellessa
The two American antennas of the international collaboration Ligo-Virgo have again observed and measured gravitational waves on January 4, 2017. The discovery, after long months of scrupulous analysis, was announced yesterday in a press conference reserved for the media around the world and it is published today on one of the most important physics reviews on an international level.
With this we enter definitively, and without more doubts, in the field of the phenomena predicted by Albert Einstein 100 years ago with his Theory of Relativity.
In short, we have a new, fundamental window with which to observe the Universe and what happens there, especially for what we can not see otherwise.
This is the case of the observation of which the physicists speak this time: two black holes that revolve around themselves, and also around one another like two ice skaters who often perform this figure, have joined, literally merged, in a single new black hole 49 times more massive than our Sun.
As expected the process has caused the emission of gravitational waves, in practice and hoping not to make the nose curl to the physicists by comparison, the distortions of the fabric of space-time that have spread to us.
We've been trying for decades, we've built the strangest and most refined tools, and finally now, after two years of success, we can say that we have this new weapon to go hunting for the truth about the universe. A new and irreplaceable weapon, given that many phenomena, like this we are talking about, are revealed only in this way.
To remember how one of these precious and sophisticated antennas works, one in Hanford, Washington, and Livingston, Louisiana, USA, we think that Einstein's space-time, which we can think of as a net fabric, is deformed by the presence of masses , as if we put more or less large billiard balls on this net. The point is that when these move generates in the network, space-time, a wave that is transmitted to the whole fabric.
The phenomenon is very light, so to speak, and therefore to be measurable from the Earth must involve some important and violent phenomenon. What can we imagine more violent than two black holes, dozens of times more massive than our sun, which merge? And indeed this is the minimum for our measurement capabilities. These waves travel and arrive on Earth, we do not hear nor see anything, until they meet one of the Ligo antennas.
This is very special, nothing to do with radio or TV antennas or similar. It is in fact two laser beams that come and go each on a 3-kilometer segment, and the two paths are at right angles to each other. When they cross each other, returning many times per second to the point where they both start, they cancel each other and nothing is measured. If instead one of the two segments is pierced by a gravitational wave before the other, as in this case, there is a phase shift and a beam arrives before the other, so they do not cancel and give a signal.
For those who remember the studies of high school or other it is interferometric measures, and we speak of course very small fractions of the millimeter and the second. The sensitivity of this equipment is at the limit of what man has been able to build up to now.
The announced discovery is important not so much because it is the umpteenth confirmation of Relativity, which has long been a theory demonstrated in all its aspects, as for the fact that it is as if we had invented a new telescope with which to see a part of the Universe that there was no foreclosure, such as the mysterious world of black holes, but the hopes are to further refine these techniques, from the ground and from space, to go straight to the time of the Big Bang, if there ever was. Beyond a certain limit back in space and time, with other techniques, it is not possible to go, we reach a maximum of 300,000 years from that fateful moment, what happened before can only be said by gravitational waves.
An important result therefore that crowns years of effort, also Franco-Italian, which are present in the international collaboration whose full name is Ligo-Virgo, where the latter is the twin antenna that the National Institute of Nuclear Physics works near Pisa. Unfortunately, in January Virgo was in extraordinary maintenance and could not participate in the party, but with the new potential that has now certainly give satisfactions to scientists. However, among the more than 1000 physics researchers of the first magnitude of the collaboration that have analyzed the data, Italians have been present from the beginning, and are preparing for the next summer waves, gravitational means.