( CNN ) -- For the past week-and-a-half , people have been marveling over the discovery of evidence supporting `` inflation , '' the theory describing the birth pangs of the Big Bang 13.7 billions years ago . What do these findings mean and how did they come about ? Lots of articles reported the news , but I am going to try to explain it in depth . Stick with me , because this is one of the most exciting astrophysical discoveries in decades . Humans have wondered about the origin of the universe for millennia , and last week 's news brought us a little closer to an answer . What this development means , basically , is that for the first time , we may be seeing what happened in the first billionth of a trillionth of a trillionth of a second of the universe . Assuming this discovery is verified by other similar experiments , it means the very birth of the universe can be studied . These will tell us about the physics of matter and energy well beyond the reach of earthly particle accelerators like the Large Hadron Collider . In a press conference on March 17 , leaders of the Background Imaging of Cosmic Extragalactic Polarization ( BICEP2 ) experiment announced their discovery of evidence of gravitational waves -- predicted by Einstein 's theory of General Relativity -- that were generated by the near-instantaneous expansion of the universe by some 50 factors of 10 , or a factor of 100 million , trillion , trillion . Those waves were predicted by the theory of inflation , developed 30 years ago by Alan Guth , Andrei Linde and others . Inflation is the instantaneous initial expansion , far faster than the speed of light , that `` describes the propulsion mechanism that drove the universe into the period of tremendous expansion that we call the Big Bang , '' as Alan Guth put it . Incidentally , the term `` Big Bang '' was coined as an insult by a physicist who did n't like the theory . The Big Bang idea itself is simple . Edwin Hubble -- after whom the Hubble Space Telescope is named -- showed more than 80 years ago that our universe is expanding . Objects in space are not hurtling outward : Space itself is becoming bigger over time . That means the distance between two galaxies grows even if neither galaxy is moving through space at all . By extrapolating the Hubble expansion backward , we have long known that the universe was once smaller by many , many factors of 10 . All the mass and energy of the entire universe squeezed into such a tiny volume would have been much hotter and denser . Then , as the universe expanded over time , the energy density went down , so the temperature cooled . This Big Bang idea implied that cool relic radiation should be visible today . Indeed , this Big Bang glow of radiation was discovered in the early 1960s by two Bell Labs engineers , Arno Penzias and Robert Wilson , who were trying to build the world 's best radio antenna . Their instrument recorded a mysterious irreducible low-level noise from every direction . Apparently worried that the surface of the antenna horn had been corrupted by , um , debris from pigeons roosting inside , the engineers repeatedly disassembled and cleaned the antenna , to no avail . Physicists later connected this measurement to the Big Bang prediction of a cosmic microwave background , for which Penzias and Wilson were awarded the Nobel Prize in 1978 . As a colleague at Bell Labs joked , referring to their obsession with pigeon droppings , `` They went looking for dung and came up with gold . For most of us [ scientists ] , it works the other way . '' The Big Bang idea was well established by the 1980s . But it did not explain important pieces of the story . First , the universe looks pretty homogeneous and isotropic -- that is , galaxies in any one direction look very similar to galaxies in the opposite direction , no matter how distant . The number of galaxies , their masses , their shapes and their stellar content are remarkably similar , to the furthest reaches we can observe . This is surprising because the Big Bang-Hubble expansion implied that very distant regions should never have been in causal contact . How then could they be so similar ? Here is a simple analogy : Imagine a thermos of ice water and a thermos of hot tea . As long as these two liquids are separate , they will have different temperatures . But if the two liquids are combined , the mixed liquid will quickly reach an intermediate temperature . Similarly , two well-separated regions of the universe can be alike only if they were at one time in contact . The theory of inflation explains this quite naturally : If at the beginning the universe inflated at an extraordinarily rapid rate -- much faster than the Hubble-measured expansion today -- then all parts of the universe visible today were once in contact . That means they had the same initial physical conditions ( such as temperature and density ) , so that similar stars and galaxies eventually formed out of the cosmic soup . Inflation also explains why the universe has a very `` flat '' geometry -- something revealed in the 1990s by analysis of the spatial distribution of tiny fluctuations ( hot and cold spots ) in the cosmic microwave background radiation . In principle , other geometries of space were possible . For example , a two-dimensional surface can be flat like a table ; convex like the surface of a sphere ( also called closed ) ; or concave like the surface of a saddle ( also called open ) . For the universe to be flat requires a very precise balance . It has infinitely more ways to be open or closed , with strong curvature , weak curvature , or anything in between . But to be flat -- well , that 's like balancing on a knife edge . Inflation naturally explains this odd fact . Specifically , the idea is that , at the very beginning , the universe must have inflated enough to stretch the fabric of space until no trace of curvature remained . Imagine inflating a beach ball to the size of the Earth : you can easily see the curvature of the beach ball in your hands but once it 's hyper-inflated , any piece of its surface seems very flat , just as the Earth feels flat locally . The enormous inflation in size would effectively erase the initial conditions in the universe . Whatever the initial temperature , for example , inflation would cool the universe to absolute zero . Even if the initial universe were very lumpy , after inflation we can see only a very smooth , local part of the original volume -- and it would seem perfectly flat . After about one hundred millionth of a trillionth of a trillionth of a second , according to theorists , whatever repulsive gravity caused inflation then transformed into a hot , dense soup of particles and energy . At this point , the Big Bang expansion that Hubble discovered took over . How inflation began and how it ended are not yet understood , but this simple idea of inflation neatly explains otherwise odd characteristics -- isotropy and flatness -- of our universe . Still , until now , there had been no direct evidence of inflation . What BICEP2 saw was the imprint of inflation on the cosmic microwave background radiation . Specifically , inflation should have generated a lot of gravitational waves -- that is , it would cause propagating ripples of space itself . Such waves have a characteristic pattern , squeezing space rhythmically in one direction then the perpendicular direction , like two hands pressing a rubber ball top to bottom then side to side . This distortion of space causes a special pattern of polarization in the Cosmic Microwave Background radiation . So what is polarization ? Light is a wave that oscillates back and forth -- polarized light oscillates preferentially in one plane . Because most light is a mix of random directions of polarization , its net polarization is zero . But any scattered light , like sunlight reflected off water , is polarized -- which is why polarized sunglasses cut down substantially on glare . BICEP2 scientists searched for that special pattern of polarization in the cosmic microwave background that would show the evidence of inflation , working for several years analyzing and reanalyzing their data . As they ran through every possible check of the analysis , team members finally began to believe they had detected the first direct signs of inflation . Now other experiment teams are redoubling efforts to find the same signal -- or to find contradictions . The reported BICEP2 signal is unexpectedly strong , so it should be within reach of at least some of these experiments . Physicists around the world know : the BICEP2 discovery is only the beginning of the story . If this result is verified by independent experiments , new , more accurate experiments will be designed to better measure the polarization imprint . This in turn will tell us about how matter and energy behave in conditions much hotter and denser than on Earth or any other place in the cosmos . As Carl Sagan once said , `` Extraordinary claims require extraordinary evidence . '' Let the observations begin . The opinions expressed in this commentary are solely those of Meg Urry .
Meg Urry describes the sequence of discoveries that lead to evidence of `` inflation '' Urry : Inflation , far faster than speed of light , happened in the first instant of the universe . Urry : Theory began 80 years ago with Edwin Hubble : He discovered a new type of galaxy called elliptical galaxies and he found them moving away from us at an incredible rate. Urry : After inflation , the universe went into more `` sedate '' pace of Big Bang we see now .