In the Italian countryside, near Pisa, a gigantic experiment is about to begin. If successfully concluded, scientists can observe directly for the first time, a major predictions Albert Einstein . If it fails, we will have to reconsider the laws of physics.
“We may have first chance to detect gravitational waves on Earth,” explains Franco Frasconi, a researcher at the University of Pisa and part of the team conducting this experiment, called Virgo. “This would be a clear demonstration that what he (Einstein) said 100 years ago is absolutely correct,” he said.
Gravitational waves everywhere
On November 25, 1915 Albert Einstein he presented the final version of his field equations to the Prussian Academy of Sciences.
These are the base . of his general theory of relativity, a pillar of modern physics that has transformed our understanding of space, time and gravity
Thanks to her we could understand many things: from the expansion of the universe to the movement of the planets and the existence of black holes.
Imagine something like the waves that are generated when you throw a stone into a pool of water.
Any object with mass It should produce when in motion. Even us. But the bigger and more dramatic mass movement, the larger waves. and Einstein predicted that the universe was filled with them.
The waves are an inevitable consequence of the general theory of relativity. Its existence has been inferred but not directly verified
They are ripples in the fabric of space and time produced by violent cosmic events The acceleration of the masses produces waves propagating at the speed of light .
promising Renewal
While astronomers have indirect evidence of their existence, no one has yet been able to observe these cosmic oddities.
“No wonder we have not yet seen gravitational waves,” says Toby Wiseman, a physicist at Imperial College London (UK).
“Gravity is in fact the weakest forces and even the most dramatic astrophysical sources emit only weak gravitational waves. “
Now, in Italy, researchers hope to find them. But it will not be easy. The first time you launched the Virgo experiment was in 2007, and failed to see anything.
Another laboratory in the United States, the Observatory laser interferometric gravitational wave (LIGO, for its acronym in English) also had no luck.
Both -called interferómetros- instruments are being renovated and task teams expect these updates allow so.
Slight distortions
What the researchers are trying to do is detect the tiny distortions that are created when gravitational waves pass through the Earth.
They expect to see waves emanated by violent cosmic events, such as exploding stars or the collision of black holes.
The Virgo detector consists of two identical tunnels 3 km distributed in the form of ‘L’. The process begins with the generation of a laser beam which is then divided into two. One is driven through a tunnel and the other half on the other
A mirror each tunnel bounces laser light many times until they become to recombine
It may seem an elaborate strategy, but takes the laser a useful property. the fact that light rays are intense. And light is a wave.
Now, imagine that two ocean waves crash against each other. While one is at its highest point, the other is at the point of depression. They can cancel each other.
The same can happen in the experiment. If the waves traveled exactly the same distance from the two tunnels, they cancel and do not produce any signal.
However, if a wave has traveled through the tunnel subtly distort their environment, changing the length of tunnels in a tiny amount (a fraction of the width of an atom).
And the way the waves move through space means that a tunnel will stretch and shrink the other, what This will make a laser beam traveling a slightly greater distance, while the other will make a shorter trip
As a result, the divided beams are recombined in a different way. light waves interfere with each other in Once canceled and scientists can then detect a signal.
collaboration
However, a signal in Italy is not enough. If there is unable to detect a gravitational wave, also should find the LIGO, US project, whose instrument is similar to Virgo and another slightly smaller experiment in Germany.
LIGO and Virgo is already running into action later this year. Both teams are so confident that the experiments are successful they believe the discovery will be exactly the January 1, 2017.
If the waves do not have to say that Needless to redesign the experiments. And in the worst case, physicists may be forced to rethink how the universe works.
But direct observation will open a new window to the cosmos, one that would not have been possible without Einstein .
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