One of the biggest questions to date pertains to the expansion of the universe since the “Big Bang”. While some believe the universe is expanding rapidly, still others think the universe is moving outward at a much slower pace. Which idea is correct?
Fast or slow
The basic idea that the universe is expanding at a rapid pace comes from observation of supernovae. Different types of supernovae have been found, for instance, type Ia supernovae, which are uniform and used as beacons to probe the outer reaches of space. Peter Milne of the Department of Astronomy and Steward Observatory reported that supernovae are found in many different populations with varying degrees of brightness. This poses many questions following.
“Differences in brightness are not random. There are two categories of supernovae: the nearby minority and the distant majority stars,” said Milne.
According to the idea of consistent growth, previous assumptions say that supernovae are the same whether near or far, moving at the same rate of expansion. This could be false. Contrary to previous belief, signs point to a recent rapid expansion.
The popular idea of a rapidly expanding universe
The view of the fast bursting universe resulted in the 2011 Nobel Prize in Physics granted to Brian P. Schmidt and three other scientists. They all believed that dim stars signified supernovae which moved farther away from the other stars, much farther than they should, and at a faster pace. This is what stemmed the belief that the speed that galaxies move away from each other is increasing.
“Many scientists use the type la supernovae as a guidepost. Type Ia supernovae are all similar-shine equally bright after they explode- than other stars in the galaxy. Since they should be the same as other stars, but are not, scientists assume they are farther away, pushed by rapid expansion,” says Milne.
Observations from The Hubble Space Telescope and NASA’s Swift Satellite were used to study type Ia supernovae in ultraviolet and visible light. Milne, together with Ryan J. Foley of the University of Illinois-Urbana Campaign, Gautham Narayan of the National Optical Astronomy Observatory of Tucson and Peter J. Brown of Texas A&M collected crucial data with these instruments. Differences between the shifts from blue to red or vice versa (indicating different populations of supernovae) were followed by observations in the ultraviolet light.
“Results are great!” Says Neil Gehrels investigator of the Swift Satellite. “This shows how our satellite can respond to new phenomenon in a quick manner.”
As it turns out, color differences, gauged by scientific study and observation, may result in different categories of supernovae and not so much distance. What we originally thought to be distant stars may just be “different” stars with different color signatures. Since there may not be such drastic expansion, then there may also be less dark matter to take into account.
Maybe the universe is not expanding as fast as believed. What we once believed to be a rapidly expanding universe pulled apart by dark matter may be more complicated still. More research is needed to conclusively point to the right direction. Scientists and instruments will gain more information soon and we will be well on our way to a deeper understanding of how the universe operates. Fast or slow, we just don’t know…not yet.