Three sci­en­tists

Physics award is for their re­search on ex­o­plan­ets, dark en­ergy, dark mat­ter

The Washington Post - - FRONT PAGE - BY SARAH KA­PLAN sarah.ka­[email protected]­post.com

were awarded the No­bel Prize in physics for re­search on ex­o­plan­ets and the struc­ture of the uni­verse.

A cos­mol­o­gist who re­vealed that the uni­verse was made mostly of in­vis­i­ble mat­ter and en­ergy, and two sci­en­tists who de­tected the first planet or­bit­ing an alien star, were jointly awarded the 2019 No­bel Prize in physics Tues­day.

By study­ing the ear­li­est mo­ments af­ter the birth of the uni­verse, James Pee­bles of Prince­ton Univer­sity de­vel­oped a the­o­ret­i­cal frame­work for the evo­lu­tion of the cos­mos that led to the un­der­stand­ing of dark en­ergy and dark mat­ter — sub­stances that can’t be ob­served by any sci­en­tific in­stru­ments but none­the­less make up 95 per­cent of the uni­verse.

Fel­low lau­re­ates Michel Mayor and Di­dier Queloz of the Univer­sity of Geneva rev­o­lu­tion­ized as­tron­omy, the No­bel Com­mit­tee said, when in 1995 they an­nounced the dis­cov­ery of a large, gaseous world cir­cling a star 50 light-years from our sun — the first ex­tra­so­lar planet found around a sun-like star.

“This year’s No­bel lau­re­ates in physics have painted a pic­ture of a uni­verse far stranger and more won­der­ful than we ever could have imag­ined,” Ulf Daniels­son, a No­bel Com­mit­tee mem­ber, said at a news con­fer­ence. “Our view of our place in the uni­verse will never be the same again.”

For al­most a cen­tury, sci­en­tists have the­o­rized that the uni­verse be­gan with a big bang, grow­ing from a hot, dense par­ti­cle soup into the cur­rent col­lec­tion of dust, stars and gal­ax­ies flung across a vast and still-ex­pand­ing space. Fifty years ago, a pair of ra­dio as­tronomers stum­bled upon the sig­na­ture of those ear­li­est days of ex­pan­sion: the cos­mic mi­crowave back­ground, a faint form of ra­di­a­tion that suf­fuses the en­tire sky.

By an­a­lyz­ing tiny vari­a­tions in this an­cient af­ter­glow, sci­en­tists can peer back in time to un­der­stand how the uni­verse evolved. Pee­bles stud­ied the tem­per­a­ture of the cos­mic mi­crowave back­ground to un­der­stand the mat­ter that was cre­ated in the big bang.

“It was, con­cep­tu­ally, a dooropen­ing event,” said ob­ser­va­tional cos­mol­o­gist San­dra Faber, a staff mem­ber at Univer­sity of Cal­i­for­nia Ob­ser­va­to­ries. “It showed that known laws of physics could ex­plain the uni­verse when it was only 100 sec­onds old. Isn’t that amaz­ing?”

Pee­bles also de­vel­oped tools for ex­plain­ing how the uni­verse as we know it came to be. Tiny quan­tum fluc­tu­a­tions that oc­curred dur­ing in­fla­tion — a pe­riod of rapid ex­pan­sion of the uni­verse that un­folded in less than one-mil­lionth of a se­cond af­ter the big bang — gave rise to “lumps” of mat­ter that would even­tu­ally evolve into gal­ax­ies, he said. These lumps, along with the still-mys­te­ri­ous dark mat­ter, ex­plain the size, shape and dis­tri­bu­tion of gal­ax­ies we see to­day.

“I was not work­ing alone,” Pee­bles said via a phone in­ter­view at the news con­fer­ence Tues­day, point­ing out that re­searchers in the So­viet Union pro­vided im­por­tant con­tri­bu­tions to sci­en­tists’ un­der­stand­ing of the uni­verse’s evo­lu­tion.

The first ex­o­planet ob­served by Mayor and Queloz wasn’t vis­i­ble through any te­le­scopes. In­stead, the as­tronomers in­tu­ited the world’s ex­is­tence by ob­serv­ing the way it af­fected its star.

If a planet is suf­fi­ciently large, rel­a­tive to its sun, it will cause the star to wob­ble just a bit. This wob­ble pro­duces tiny shifts in the light the star emits, and sci­en­tists can an­a­lyze these shifts to de­ter­mine the size and dis­tance of the planet.

The first world that Mayor and Queloz dis­cov­ered, dubbed 51 Pe­gasi b, is un­like any in our so­lar sys­tem. The planet is large and gaseous, like Jupiter, but is so close to its star that it takes just four days to com­plete an or­bit. Its tem­per­a­ture ex­ceeds 1,000 de­grees Cel­sius.

When Queloz first saw the planet’s sig­na­ture in his data, “I pan­icked,” re­called the sci­en­tist, who was a grad­u­ate stu­dent work­ing with Mayor at the time of the dis­cov­ery. “I thought some­thing was wrong with the in­stru­ment.”

It took much re­anal­y­sis for the as­tronomers to con­vince them­selves that they were look­ing at some­thing real. Then they had to per­suade the rest of the world. The planet was so dif­fer­ent from what sci­en­tists pre­dicted they would find, many re­searchers were ini­tially skep­ti­cal of the dis­cov­ery.

“New science is very rarely done by just one per­son . . . and there were a lot peo­ple who made im­por­tant con­tri­bu­tions be­fore and since then,” said Jo­hanna Teske, an ex­o­planet as­tronomer at Carnegie Ob­ser­va­to­ries. But Mayor and Queloz’s dis­cov­ery “was re­ally a turn­ing point for the field.”

Soon, as­tronomers across the globe were con­duct­ing their own ex­o­planet searches, scan­ning the skies and look­ing over reams of his­tor­i­cal data to de­tect the tell­tale wob­ble of a planet-host­ing sun. Ob­ser­va­tions from ground-and space-based te­le­scopes have re­vealed more than 4,000 con­firmed ex­o­plan­ets and chal­lenged sci­en­tists’ no­tions about how plan­e­tary sys­tems evolve.

Last year, NASA launched the Tran­sit­ing Ex­o­planet Sur­vey Satel­lite, a pow­er­ful space tele­scope that will scan the en­tire sky seek­ing out worlds cir­cling nearby stars. Of par­tic­u­lar in­ter­est to the mis­sion are rocky worlds or­bit­ing near enough to their stars to po­ten­tially have liq­uid wa­ter on their sur­faces.

“When [Mayor and Queloz] were study­ing and look­ing for these ex­o­plan­ets, peo­ple would laugh at them . . . and call it science fic­tion,” Teske said. “To see it come from there all the way to now, where they’re win­ning No­bel Prizes and we’re get­ting ever closer to find­ing and char­ac­ter­iz­ing Earth­like plan­ets, it’s great and ex­cit­ing and a lit­tle sur­real.”

The an­nounce­ment Tues­day prompted de­bate over the lack of di­ver­sity among re­cip­i­ents. Just three women have ever been awarded the physics prize in its more than 100-year his­tory, and no black sci­en­tist has ever been rec­og­nized.

The wo­man who proved the ex­is­tence of dark mat­ter, Vera Ru­bin, was not given the award be­fore her death in 2016 (No­bels are not awarded posthu­mously).

“She was and con­tin­ues to be hugely in­flu­en­tial and in­spi­ra­tional for ev­ery­one in as­tron­omy,” Teske said of Ru­bin. “It’s par­tic­u­larly ironic in a not so nice way for her not to have been rec­og­nized, and I think that will just con­tinue to be, at least for me, a sore spot when any No­bel Prize in physics is awarded.”

The Royal Swedish Academy of Sci­ences, which awards the prizes, told Na­ture last week the or­ga­ni­za­tion had im­ple­mented mea­sures to ad­dress bias against women and sci­en­tists of color, in­clud­ing ex­plic­itly ask­ing nom­i­na­tors to con­sider di­ver­sity in gen­der, ge­og­ra­phy and topic. All six re­cip­i­ents of this year’s prizes for medicine and physics have been white men.

Faber said Pee­bles’s work “ranged from the big bang to quan­tum me­chan­ics to the true na­ture of dark mat­ter.” His the­ory “tells the hu­man race that we were born ac­cord­ing to the laws of physics and the im­pli­ca­tion is we need to live by those.”

Much as Pee­bles’s re­search em­pha­sized hu­mans’ in­signif­i­cance in the con­text of the uni­verse, Mayor’s and Queloz’s dis­cov­ery re­vealed how rare and un­usual we are. The vast ma­jor­ity of ex­o­plan­ets dis­cov­ered in the past two decades are un­like any body in our own so­lar sys­tem.

Still, Daniels­son, the No­bel com­mit­tee mem­ber, said some­where in the vast and in­scrutable uni­verse, on one of those strange and dis­tant worlds, it’s pos­si­ble that some other form of life ex­ists.

It might take years, or cen­turies, or even mil­len­nia, he said. But he holds out hope that one day, hid­den in the dark­ness, hu­man­ity will find ev­i­dence that we are not alone.

PHO­TOS BY AS­SO­CI­ATED PRESS

From left, No­bel Prize re­cip­i­ents James Pee­bles, Di­dier Queloz and Michel Mayor. The re­searchers “have painted a pic­ture of a uni­verse far stranger and more won­der­ful than we ever could have imag­ined,” No­bel Com­mit­tee mem­ber Ulf Daniels­son said.

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