"Long before it's in the papers"
January 18, 2011

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A “fundamental” number may be shifty, astronomers say

Sept. 7, 2010
Courtesy of JENAM
(Joint Eu­ro­pe­an and Na­tional As­tron­o­my Meet­ing)
and World Science staff

A num­ber tra­di­tion­ally be­lieved to be the same uni­verse-wide, and which char­ac­ter­izes the strength of elec­tricity and mag­net­ism, ac­tu­ally varies from place to place, ac­cord­ing to a new stu­dy.

As­tro­no­mers in­volved in the re­search pre­dict it will gen­er­ate con­tro­ver­sy be­cause it could force a re­think­ing of the founda­t­ions of phys­ics. It might among oth­er things imply that the uni­verse is in­fi­nitely large, they add.

A qua­sar des­ig­nat­ed 3C273 as ob­served by the Hub­ble Space Tel­e­scope. (Cred­it: NA­SA/STScI)

The sci­ent­ists are slated to pre­s­ent the find­ings on Sept. 8 at the Joint Eu­ro­pe­an and Na­tional As­tron­o­my Meet­ing in Lis­bon, Por­tu­gal, and have sub­mit­ted a pa­per to the jour­nal Phys­i­cal Re­view Let­ters.

The re­search team, led by John Webb of the Uni­vers­ity of New South Wales, Aus­tral­ia, stud­ied qua­sars, very dis­tant ga­lax­ies wit­ness­ing vi­o­lent pro­cesses at their cores due to gi­ant black holes that lie there.

This fu­ri­ous ac­ti­vity gen­er­ates bright light that trav­els through the cos­mos. Part of this light is ab­sorbed by var­i­ous atoms in clouds in space. The ab­sorp­tion leaves dis­tinc­tive sig­na­tures on the light’s colors, of­fer­ing as­tro­no­mers a fur­ther op­por­tun­ity to study nat­u­ral pro­cesses bil­lions of light-years away. A light-year is the dis­tance light trav­els in a year.

Webb and col­leagues used these pro­cesses to es­ti­mate a num­ber known as the fi­ne-struc­ture con­stant, which char­ac­ter­izes the strength of the so-called elec­tro­mag­netic force. This force de­ter­mines the strength of elec­tric and mag­net­ic fields, which are so closely in­ter­twined that they are treated as a sin­gle force. Light, in­deed, is simply an os­cilla­t­ion of in­ter­wo­ven elec­tric and mag­net­ic fields.

Webb said his re­sults imply that the fi­ne-struc­ture con­stant might have dif­fer­ent val­ues de­pend­ing on which di­rec­tion we are look­ing in the sky, thus be­ing not so “con­stant” af­ter all.

“The pre­ci­sion of as­t­ro­phys­i­cal mea­sure­ments of the fi­ne struc­ture con­stant, or al­pha, dra­mat­ic­ally in­creased about a dec­ade ago,” Webb said, when he and a col­league in­tro­duced a new meth­od for meas­ur­ing the fig­ure. “S­ince then ev­i­dence started mount­ing, sug­gest­ing this cru­cial phys­i­cal quanti­ty might not be the same every­where.”

Varia­t­ion by place in the “con­stant” ap­pears to be much more than varia­t­ion by time, if there is any, added the re­search­ers.

They claim that the im­plica­t­ions of these re­sults are so re­sound­ing that they will probably cause con­tro­ver­sy in the sci­en­tif­ic com­mun­ity.

Us­ing two ma­jor ob­ser­va­to­ries, the Keck Tel­e­scope in Ha­waii and the Eu­ro­pe­an South­ern Ob­ser­va­to­ry’s Very Large Tel­e­scope in Chil­e, Webb and his team ob­served the light from qua­sars, the most lu­mi­nous ob­jects in the known uni­verse. Al­though qua­sars are in­credibly far away, we can de­tect them due to the sheer quan­tity of light that they emit. The light is thought to come from ma­te­ri­al that heats up as it plunges in­to the cent­ral, “su­per­mas­sive” black holes.

Be­cause the light that reaches us from these ob­jects ac­tu­ally left them bil­lions of years ago, the im­ages we re­ceive of­fer a rec­ord of the way they would have looked back then.

“The in­ter­ac­tion of the light from the quasars with the gas clouds pro­vides an im­pres­sive op­por­tun­ity to in­ves­t­i­gate the phys­i­cal con­di­tions when the Uni­verse was just a frac­tion of its cur­rent age,” said PhD stu­dent Jul­ian King, al­so of the uni­vers­ity, who played a ma­jor role in the re­search. It’s “ex­cit­ing that we have the tech­nol­o­gy to be able to meas­ure the laws of phys­ics in the early Uni­verse so pre­cise­ly,” he added.

The new re­sults can be ex­plained if our Uni­verse is ex­cep­tion­ally or even in­fi­nitely large, the re­search­ers said. This would al­low fun­da­men­tal quan­ti­ties and “con­stants” to have dif­fer­ent val­ues in diff­erent areas. In such a sce­nar­i­o, we would ex­ist in just a ti­ny patch of the cos­mos, with cor­re­spond­ingly small changes in the phys­i­cal con­stants.

This view, the sci­ent­ists said, raises ques­tions as to why a whole range of these “con­stants” hap­pen to be just right—in our area—for de­vel­op­ing life, along with phys­ics and chem­is­try as we know them.

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A number traditionally believed to be the same universe-wide, and which characterizes the strength of electricity and magnetism, actually varies from place to place, according to a new study. Astronomers involved in the research predict that the study will generate controversy because it could force a rethinking of the foundations of our current knowledge of physics. It might also imply that the universe is infinitely large, they added. The scientist plan to present the findings on Sept. 8 at the Joint European and National Astronomy Meeting in Lisbon, Portugal, and have submitted a paper to the journal Physical Review Letters. The research team, led by John Webb of the University of New South Wales, Australia, studied quasars, very distant galaxies witnessing violent processes at their cores due to giant black holes that lie there. This furious activity generates bright light that travels through the cosmos. Part of this light is absorbed by various atoms in clouds in space, providing astronomers with a further opportunity to study natural processes billions of light-years away. A light-year is the distance light travels in a year. Webb and colleagues used these processes to estimate a number known as the fine-structure constant, which characterizes the strength of the so-called electromagnetic force. This force is determines the strength of electric and magnetic fields, which are so closely intertwined that they are treated as a single force. Light, indeed, is simply an oscillation of interwoven electric and magnetic fields. Webb said his results imply that the fine-structure constant might have different values depending on which direction we are looking in the sky, thus being not so “constant” after all. “The precision of astrophysical measurements of the fine structure constant, or alpha, dramatically increased about a decade ago,” Webb said, when he and a colleague introduced a new method for measuring the figure. “Since then evidence started mounting, suggesting this crucial physical quantity might not be the same everywhere.” Variation by place in the “constant” appears to be much more than variation by time, if there is any, added the researchers. They claim that the implications of these results are so resounding that they will probably cause controversy in the scientific community. Using two major observatories, the Keck Telescope in Hawaii and the European Southern Observatory’s Very Large Telescope in Chile, Webb and his team observed the light from quasars, the most luminous objects in the known universe. Although quasars are incredibly far away, we can detect them from the Earth due to the sheer quantity of light that they emit, likely caused by material falling into supermassive black holes at their centers. Because the light that reaches us from these objects actually left them billions of years ago, the images we receive offer a record of the way they would have looked back then. “The interaction of the light from the quasars with the gas clouds provides an impressive opportunity to investigate the physical conditions when the Universe was just a fraction of its current age,” said PhD student Julian King, also of the university, who played a major role in the research. It’s “exciting that we have the technology to be able to measure the laws of physics in the early Universe so precisely,” he added. The new results collected by Webb and his team can be explained if our Universe is in fact exceptionally or indeed infinitely large, the researchers said. This would allow fundamental quantities and “constants” to have different values from patch to patch. In such a scenario, we would exist in just a tiny part, with correspondingly small changes in the physical constants. This view, the scientists said, raises questions as to why a whole range of “constants” are just right—in our area—for developing life, along with physics and chemistry as we know them.