The Science of Sustainability

The State of the Universe: Matter and Age Up, Dark Energy Down

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Smile, universe, for your baby picture! Maps of the early universe by the COBE, WMAP, and Planck missions. Image credit: NASA

Smile, universe, for your baby picture! Maps of the early universe by the COBE, WMAP, and Planck missions. Image credit: NASA

On news that the universe may be 100 million years older than previously estimated, cosmological markets have seen a reduction in the benchmark of universal expansion, the Hubble Constant, down to a new low of 67.15 kilometers per second per megaparsec. This has led to a drop in the dark energy market, down from initial estimates by 3.1% to 68.3% of the total universal mass/energy inventory. On the brighter side, stocks of the highly sought-after dark matter commodities are up to 26.8%, and good-old reliable normal matter fundamentals have inched upward to 4.9%, up from the previous 4.6%.

The news comes not from Wall Street but from cosmological observations by the European Space Agency's Planck mission, and analysis of those measurements by European, NASA and Canadian scientists.

What do the numbers mean?

That the age of the universe is 100 million years greater than previously calculated is interesting, but it won't force the Barenaked Ladies to change the lyrics in the Big Bang Theory's opening theme song; "…nearly 14 billion years ago…" works whether the number is 13.7 or the more recent 13.8 billion.

The small refinements in the percentages of the universe composed of normal matter, dark matter and dark energy are probably more interesting to scientists as far as the absolute numbers go. But the mere fact that a quarter of the universe is made of stuff we can't see (dark matter) and over two-thirds of the universe is made of stuff we can neither see nor at present understand (dark energy) is a stupefying fact. It means that what we can see in the universe (planets, stars, galaxies—normal matter) is only about 5% of what's actually there. Stupefying!

Planck's mission is to measure minute differences in the brightness of the Cosmic Microwave Background (CMB) radiation, the faint glow of microwaves coming from every direction in the sky. Originally discovered by accident in 1964, CMB radiation comes from the greatest observable distances in the universe, and from the earliest time that light became able to travel freely through space.

Astronomers became very interested in these cosmic microwave emissions, for in collecting and measuring those photons they were essentially taking a picture of the very early universe, not long after the Big Bang (the theory, not the TV show). The CMB is the "afterglow of creation," and for astronomers to discover and study it was something akin to when anthropologists first found fossils of the earliest hominids.

When you look out at distant galaxies you are seeing the light that left them in the distant past—how far in the past depends on how far away the galaxy is. The most distant galaxy that we have seen is a portal back in time over 13 billion years, a time when the universe was barely past infancy. But look a bit farther into space, a bit further backward in time, and you are looking at a time before galaxies had formed from the expanding gaseous universe.

The limit of our ability to peer backward is met at the time before which the hot gases of the Big Bang aftermath were too dense for light to travel freely, and instead bounced around within the hot dense soup (those lyrics also need no adjustment) of atomic nuclei and electrons–similar to how light bounces between water droplets in a cloud. We see this far, but no farther because we are looking into an opaque cloud that existed before the universe was 370,000 years young.

As our picture-taking of the earliest face of the universe became more refined, a more detailed map of the CMB's variations in brightness was resolved, starting with the relatively blurry blotch-map brought by the COBE mission, to a more detailed all-sky image by the WMAP mission, and now the clearest picture yet by Planck.

The color variations in the map represent minute differences in the temperature and density of the gases of the early universe—subtle variations that eventually snowballed (so to speak) to become denser concentrations of matter, and the seeds of the earliest galaxies and galaxy clusters.

So, in comparing the blotchy facial features of this infant shot to photos of the universe taken at later times we have assembled a more complete life picture of how the cosmos has grown and developed. And no one had to change the lyrics of their song either!

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Category: Astronomy, Blog

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Ben Burress

About the Author ()

Benjamin Burress has been a staff astronomer at Chabot Space & Science Center since July 1999. He graduated from Sonoma State University in 1985 with a bachelor’s degree in physics (and minor in astronomy), after which he signed on for a two-year stint in the Peace Corps, where he taught physics and mathematics in the African nation of Cameroon. From 1989-96 he served on the crew of NASA’s Kuiper Airborne Observatory at Ames Research Center in Mountain View, CA. From 1996-99, he was Head Observer at the Naval Prototype Optical Interferometer program at Lowell Observatory in Flagstaff, AZ. Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.