Einstein was right

“We have detect­ed grav­i­ta­tion­al waves. We did it.”, announced David Reitze, exec­u­tive direc­tor of LIGO in a press con­fer­ence in Wash­ing­ton, on Feb 11 2016. After a cen­tu­ry of research, Ein­stein was proved right. First ever detec­tion of grav­i­ta­tion­al waves is eas­i­ly the dis­cov­ery of the cen­tu­ry, that many say, is like­ly to earn Nobel Prize. Since the birth of our species, we have been observ­ing uni­verse through what we could see, the vis­i­ble light from the first star gaz­ers, ultra­vi­o­let light and infrared light from hub­ble space tele­scopes and microwaves and radio waves blast­ing from the dis­tant galax­ies. But there are oth­er vibra­tions which we can­not see.

A hun­dred years ago, in 1916, Albert Ein­stein pro­posed gen­er­al the­o­ry of rel­a­tiv­i­ty. He pre­dict­ed that the accel­er­a­tion of mas­sive objects would dis­turb the fab­ric of space and time, send­ing out grav­i­ta­tion­al waves, nobody has detect­ed one, until now. Grav­i­ta­tion­al waves, in the sim­plest words, are rip­ples in space-time. These rip­ples car­ry grav­i­ta­tion­al ener­gy away from the accel­er­at­ing mas­sive objects in the cos­mos, with the speed of light. Just like the rip­ples pro­duced across the sur­face of a pond, when a peb­ble is dropped into water. Grav­i­ta­tion­al waves are pro­duced by extreme events, such as col­lid­ing black holes, merg­ing neu­tron stars or explod­ing stars.

Rough­ly 1.3 bil­lion years ago, two black holes, one with 36 times the mass of sun and oth­er with 29, spi­raled into each oth­er and even­tu­al­ly col­lid­ed. As a result of col­li­sion, about 3 times the mass of sun was con­vert­ed into ener­gy, in a frac­tion of sec­ond. Thus the col­li­sion unleashed this ener­gy in the form of grav­i­ta­tion­al waves, still spread­ing out­wards. As grav­i­ta­tion­al wave trav­els, it com­press­es the space in one direc­tion and stretch­es space in the oth­er, like sound waves. This push and pull weak­ens with the dis­tance. The waves ulti­mate­ly fade to a whis­per that Physi­cists long thought that grav­i­ta­tion­al waves would nev­er be mea­sured on Earth. But it final­ly hap­pened at LIGO lab­o­ra­to­ries.

Laser inter­fer­om­e­ter grav­i­ta­tion­al wave obser­va­to­ry, LIGO, is a sys­tem of two iden­ti­cal detec­tors, one locat­ed in Liv­ingston, Louisiana and the oth­er in Han­ford, Wash­ing­ton, con­struct­ed to detect incred­i­bly tiny vibra­tions from pass­ing grav­i­ta­tion­al waves. The project was cre­at­ed by sci­en­tists from Cal­tech and MIT, fund­ed by Nation­al Sci­ence Foun­da­tion. On Sep 14, 2015, at 5:51 am East­ern Day­light time (9:51 UTC), when every­body in US was slept, LIGO com­put­ers detect­ed a loud sig­nal at Liv­ingston site. Sev­en mil­lisec­onds lat­er the sig­nal hit Han­ford site. The sig­nal was con­vert­ed into sound and heard by sci­en­tists at LIGO as a chirp which last­ed mere­ly for one fifth of a sec­ond. That is how the grav­i­ta­tion­al waves pro­duced by col­li­sion of two gigan­tic black holes trav­eled through the uni­verse and reached Earth after 1.3 bil­lion years and got cap­tured by LIGO detec­tors. Lis­ten it your­self:

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Dr. Weiss, a Physi­cist at Mass­a­chu­setts Insti­tute of Tech­nol­o­gy, who came up with the idea of LIGO was on vaca­tion in Maine, found out when he logged on to his com­put­er that morn­ing. “It was wav­ing hel­lo. It was amaz­ing. The sig­nal was so big, I didn’t believe it.”, he was ecsta­t­ic. “It is by far the most pow­er­ful explo­sion humans have ever detect­ed except for the big bang.” said Pro­fes­sor Kip Thorne of Cal­i­for­nia Insti­tute of tech­nol­o­gy and one of the found­ing fathers of LIGO. “I think this will be one of the major break­throughs in Physics for a long time.” said Szaboles Mar­ka, one of LIGO sci­en­tist and Colum­bia Uni­ver­si­ty pro­fes­sor. “Every­thing else in astron­o­my is like the eye. Final­ly astron­o­my grew ears. We nev­er had ears before.”

They were going to make such a big claim that it took them so long to con­firm the data. The dis­cov­ery was announced in a press con­fer­ence in Wash­ing­ton on Feb 11, 2016. The sci­en­tists of LIGO, along with sci­en­tists from VIRGO Col­lab­o­ra­tion pub­lished it in a report in Phys­i­cal Review Let­ter with more than 1000 authors, on the same day. Proud­ly men­tion­ing that one of the co-authors of this land­mark pub­li­ca­tion is a Pak­istan-born Astro­Physi­cist Dr. Ner­gis Maval­vala, Asso­ciate Depart­ment head of Physics at MIT. In a field dom­i­nat­ed by men, Dr. Maval­vala is an inspi­ra­tion, as we need more women in STEM fields and more glo­ri­fi­ca­tion of STEM careers.