Have you said “Gravitational waves”?!

Exactly 100 years ago, as far back as 1916, Einstein predicted what was recently detected by scientists from LIGO: GRAVITATIONAL WAVES!!! Am I discover hot water? Of course I’m not. Everybody hears this  but I think that not all of them are aware about what this  really means.

This is a huge discovery, because it confirms Eistein’s theory and also because it opens us a new way to explore universe. Now the question is: how was it was possible that 100 years ago, one scientist, without any instruments, was able to predict this? Well, to answer this question I want to quote George Clooney  in a famous italian coffee spot

“Immagina, puoi”

which literally means “Imagine, you can”.

So, what is a gravitational wave and how does it change everything? A gravitational wave is actually a ripple in the fabric of space. Is it difficult to figure out what it exactly is? Imagine to throw out a stone in the pond. What happens? The water ripples. In this case the ripples are not the water but in the space itself. Einstein’s General Relativity, which was discovered a year earlier in the 1915, may help us to understand better this phenomenon. In this case the key idea is that the gravity deforms and curves the fabric of space.

einsteingravity
The yellow ball, deforming the space, keeps the blue ball rotate.

This was in 1915, but Eistein went on imagining the space as a trampoline, in which balls fall down on it causing ripples in the surface. He supposed that the same should be true for the fabric of space where 2 neutron stars or black holes orbiting create ripples in the fabric of space. His Maths predicts that this rotation will generate a steady march of ripples in the fabrice of space. The same ripples which have been detected by LIGO’s scientists few days ago. His math also predicted that as a gravitational wave ripples by anything it will strech and compress. This means that because we are part of the space we are streching and compressing along with the rippling of the space. Why don’t we feel this streching and compressing? Just because the order of magnitude of this streching and compressing is by less than an atomic diameter!

Now that we know that gravitational waves are bending the space, how is it that we see the universe in a different way? Imagine someone in front of you who is covering his/her face: now you can’t see his/her face, right? As you can see  light can be blocked. Gravity can’t be blocked: gravity can go to places in the universe that light cannot penetrate. So using this gravitation disturbences scientist may be able to study how black holes combine and maybe ven the Big Bang itself.

If you are not sure enough about the truthfulness of this discover, consider that the statistical significance of this experiment is supposedly very high, exceeding the “five-sigma” standard that physicists use to distinguish evidence strong enough to claim discovery. In short, 5 sigma is a measure of how confident scientists feel their results are. If experiments show results to a 5 sigma confidence level, that means if the results were due to chance and the experiment was repeated 3.5 million times then it would be expected to see the strength of conclusion in the result no more than once. To be cooler, five-sigma corresponds to a p-value, or probability, of 3×10^-7, testing the hypotesis of false alarm.

A GRAPH OF THE NORMAL DISTRIBUTION, SHOWING 3 STANDARD DEVIATIONS ON EITHER SIDE OF THE MEAN . A FIVE-SIGMA OBSERVATION CORRESPONDS TO DATA EVEN FURTHER FROM THE MEAN. SOURCE: WIKIMEDIA COMMONS/MWTOEWS
A GRAPH OF THE NORMAL DISTRIBUTION, SHOWING 3 STANDARD DEVIATIONS ON EITHER SIDE OF THE MEAN . A FIVE-SIGMA OBSERVATION CORRESPONDS TO DATA EVEN FURTHER FROM THE MEAN. SOURCE: WIKIMEDIA COMMONS/MWTOEWS

The origin of universe is for me one of the most fashinating and inspiring facts as well as statistics and the application this science to our lives and studies is. It would be more correct if I had talked about space-time, not just about space itself, but that would had complicated things.

Want to know more about space-time?

 

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