A signature of the big bang
Today, we'll look at the past, a very old one -- 13.7 billion years to be precise. According to a Cornell University news release, some new satellite data has revealed the beginnings of the universe. This data, based on measurements of the cosmic microwave background radiation (CMB), confirms the theory of what happened during the first trillionth of existence of our universe and its age. It also contributes to explain why the expansion of our universe is accelerating by relating the forces behind the initial big bang and this current expansion.
Here is the introduction of the Cornell University news release.
Looking back 13.7 billion years, astronomers have collected data that tells us, with greater precision than ever before, what happened in the first two-trillionths of a second after the big bang. The data agrees very well with theoretical predictions and may tell us something about the way the universe is behaving today, particularly why it is expanding faster than it ought to be.
"Observation is helping us constrain the theories," said Rachel Bean, Cornell assistant professor of astronomy, who is both a cosmology theorist and a member of the Wilkinson Microwave Anisotropy Probe (WMAP) team, which on March 10 released a high-resolution picture of the cosmic microwave background radiation (CMB), a sort of signature of the big bang.
Here is a small version of this map (Credit:WMAP). "Colors indicate 'warmer' (red) and 'cooler' (blue) spots. The white bars show the 'polarization' direction of the oldest light. This new information helps to pinpoint when the first stars formed and provides new clues about events that transpired in the first trillionth of a second of the universe."
But what happened during the big bang?
At the big bang, theory says, all the matter and energy in the universe was compressed into a space about a trillionth of a trillionth of a trillionth of a meter across. The laws of physics don't allow measurements smaller than that. As soon as it came into being, it exploded, at first releasing a field of undirected energy filled with massive particles dubbed "inflatons" that carry a sort of negative gravity, propelling everything outward. By the end of the first trillionth of a second, the inflatons had decayed into a seething plasma of elementary particles and energy in the form of photons.
If you want to know more about inflatons, please read this page at Wikipedia.
Anyway, it's amazing what happened in a trillionth of a second -- and in the early age of our universe.
About 400,000 years later -- an eyeblink in universe time -- the universe had expanded and cooled enough for electrons and protons to form hydrogen atoms without photons crashing into them and knocking them apart. Photons readily interact with electrons but hardly ever with neutral hydrogen, so once atoms formed, the primeval light was able to travel unhindered through the universe.
And here is an illustration showing the time line of the universe (Credit:WMAP).
So what can we conclude from this new satellite data?
Among other conclusions, the new data confirms the age of the universe at 13.7 billion years and says that the universe is almost "flat" (that is, space is only curved a bit through a higher dimension). As for dark energy, Bean said the results are consistent with the simplest theory, a "cosmological constant" representing a fundamental property of space, meaning that dark energy has the same value at every point in space and time.
Finally and for your pleasure, you can find larger versions of the images above on a WMAP page about their results on the oldest light in the universe.
Sources: Bill Steele, Cornell University, via EurekAlert!, March 28, 2006; and various web sites
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