Latest research deflates the ideathat the Universe cycles for eternity.
Circular ripples in the cosmic microwavebackground have been making waves with theoreticians.NASA
Our viewof the early Universe may be full of mysterious circles — and even triangles —but that doesn't mean we're seeing evidence of events that took place beforethe Big Bang. So says a trio of papers taking aim at a recent claim thatconcentric rings of uniform temperature within the cosmic microwave background— the radiation left over from the Big Bang — might, in fact, be the signaturesof black holes colliding in a previous cosmic 'aeon' that existed before ourUniverse.
Theprovocative idea was posited by Vahe Gurzadyan of Yerevan Physics Institute in
Armenia and celebrated theoretical physicistRoger Penrose of the University of Oxford, . In a recent paper1, posted on the arXiv preprint server,Gurzadyan and Penrose argue that collisions between supermassive black holesfrom before the Big Bang would generate spherically propagating gravitationalwaves that would, in turn, leave characteristic circles within the cosmicmicrowave background. UK
To verifythis claim, Gurzadyan examined seven years' worth of data from NASA's WilkinsonMicrowave Anisotropy Probe (WMAP) satellite, calculating the change intemperature variance within progressively larger rings around more than 10,000points in the microwave sky. And indeed, he identified a number of rings withinthe WMAP data that had a temperature variance that was markedly lower than thatof the surrounding sky.
Mostcosmologists believe that the Universe, and with it space and time, explodedinto being some 13.7 billion years ago at the Big Bang, and that it has beenexpanding ever since. A crucial component of the standard cosmological model —needed to explain why the Universe is so uniform — is the idea that a fractionof a second after the Big Bang, the Universe underwent a brief period ofextremely rapid expansion known as inflation.
Vahe Gurzadyan and Roger Penrose.V.Gurzadyan, R.Penrose
Penrose,however, thinks that the Universe's great uniformity instead originates frombefore the Big Bang, from the tail end of a previous aeon that saw the Universeexpand to become infinitely large and very smooth. That aeon in turn was bornin a Big Bang that emerged from the end of a still earlier aeon, and so on,creating a potentially infinite cycle with no beginning and no end.
NowGurzadyan and Penrose's idea is being challenged by three independent studies,all posted on the arXiv server within the past few days, by Ingunn Wehus andHans Kristian Eriksen of the University of Oslo2; Adam Moss, Douglas Scott and JamesZibin of the University of British Columbia3 in Vancouver, Canada; and AmirHajian of the Canadian Institute for Theoretical Astrophysics in Toronto,Ontario4.
Allthree groups reproduced Gurzadyan's analysis of the WMAP data and all agreethat the data do contain low-variance circles. Where they part company with theearlier work is in the significance that they attribute to these circles.
Circles of significance
To gauge this significance, Gurzadyan comparedthe observed circles with a simulation of the cosmic microwave background inwhich temperature fluctuations were completely scale invariant, meaning thattheir abundance was independent of their size. In doing so, he found that thereought not to be any patterns. But the groups who are critical of his work saythat this is not what the cosmic microwave background is like.
Theypoint out that the WMAP data clearly show that there are far more hot and coldspots at smaller angular scales, and that it is therefore wrong to assume thatthe microwave sky is isotropic. All three groups searched for circular variancepatterns in simulations of the cosmic microwave background that assume thebasic properties of the inflationary Universe, and all found circles that arevery similar to the ones in the WMAP data.
Moss andhis colleagues even carried out a slight variation of the exercise and foundthat both the observational data and the inflationary simulations also containconcentric regions of low variance in the shape of equilateral triangles."The result obtained by Gurzadyan and Penrose does not in any way provideevidence for Penrose's cyclical model of the Universe over standard inflation,"says Zibin.
Gurzadyandismisses the critical analyses as "absolutely trivial", arguing thatthere is bound to be agreement between the standard cosmological model and theWMAP data "at some confidence level" but that a different model, suchas Penrose's, might fit the data "even better" " — a point hemakes in a response to the three critical papers also posted on arXiv5. However, he is not prepared to statethat the circles constitute evidence of Penrose's model. "We have foundsome signatures that carry properties predicted by the model," he says.