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Roj47

Universe bigger and older than thought

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A project aiming to create an easier way to measure cosmic distances has instead turned up surprising evidence that our large and ancient universe might be even bigger and older than previously thought.

If accurate, the finding would be difficult to mesh with current thinking about how the universe evolved, one scientist said.

A research team led by Alceste Bonanos at the Carnegie Institution of Washington has found that the Triangulum Galaxy, also known as M33, is about 15 percent farther away from our own Milky Way than previously calculated.

The finding, which will be detailed in an upcoming issue of Astrophysical Journal, suggests that the Hubble constant, a number that measures the expansion rate and age of the universe, is actually 15 percent smaller than other studies have found.

Currently, most astronomers agree that the value of the Hubble constant is about 71 kilometers per second per megaparsec (a megaparsec is 3.2 million light-years). If this value were smaller by 15 percent, then the universe would be older and bigger by this amount as well.

Scientists now estimate the universe to be about 13.7 billion years old (a figure that has seemed firm since 2003, based on measurements of radiation leftover from the Big Bang) and about 156 billion light-years wide.

The new finding implies that the universe is instead about 15.8 billion years old and about 180 billion light-years wide.

http://www.space.com/scienceastronomy/0608...ble_revise.html

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I read this article also and it made me think that perhaps other calculations made by scientists have benn innaccurate over the years.

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Posted (edited)

I read this article also and it made me think that perhaps other calculations made by scientists have benn innaccurate over the years.

Of course some are. If science knew every thing the research scientists could all pack up and retire. Science is a continuing search for knowledge. New theories over take old. Newton was replaced by Einstien. But with each new discovery the depth of human knowledge increases slightly. If you want "absolute truth" then that is the realm of religion.

Edited by Waspie_Dwarf

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I put this in the other thread (in Main News) but since there are two threads I must as well include it here as well. It was announced yesterday that a study using the Chandra X-ray observatory has used a unique method to measure the Hubble constant; their results are in line with the consensus value:

By combining X-ray data from Chandra with radio observations of galaxy clusters, the team determined the distances to 38 galaxy clusters ranging from 1.4 billion to 9.3 billion light years from Earth. These results do not rely on the traditional distance ladder. Bonamente and his colleagues find the Hubble constant to be 77 kilometers per second per megaparsec (a megaparsec is equal to 3.26 million light years), with an uncertainty of about 15%.

This result agrees with the values determined using other techniques. The Hubble constant had previously been found to be 72, give or take 8, kilometers per second per kiloparsec based on Hubble Space Telescope observations. The new Chandra result is important because it offers the independent confirmation that scientists have been seeking and fixes the age of the Universe between 12 and 14 billion years.

"These new results are entirely independent of all previous methods of measuring the Hubble constant," said team member Marshall Joy also of MSFC.

The astronomers used a phenomenon known as the Sunyaev-Zeldovich effect, where photons in the cosmic microwave background (CMB) interact with electrons in the hot gas that pervades the enormous galaxy clusters. The photons acquire energy from this interaction, which distorts the signal from the microwave background in the direction of the clusters. The magnitude of this distortion depends on the density and temperature of the hot electrons and the physical size of the cluster. Using radio telescopes to measure the distortion of the microwave background and Chandra to measure the properties of the hot gas, the physical size of the cluster can be determined. From this physical size and a simple measurement of the angle subtended by the cluster, the rules of geometry can be used to derive its distance. The Hubble constant is determined by dividing previously measured cluster speeds by these newly derived distances.

Press release

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So the universe was previously 13 and decided it didn't look old enough and wanted to be 15? How long before it can get into rated R movies. ;)

Man, just when I think I finally have the geologic time scale and age of the universe finally memorized...

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Posted (edited)

Little bit more news today (or yesterday, I suppose). Three of the coauthors on the paper the space.com article is about, including Kris Stanek, have coathored another paper that'll soon be published in the Astrophysical Journal on calibrating the Cepheid distance scale. Cepheids are variable stars that have a certain relation between their period of variability and their absolute magnitude. Thus by observing how long a Cepheid's bright-dim-bright cycles take we can figure out how bright it is and from that it's not hard to figure out how far away it is.

Anyway, the relevant bit here is that this paper uses this calibration of the Cepheid Distance Scale to estimate the value of the Hubble constant. They get a value of 74 km/s/Mpc which is pretty close to the accepted value of about 72 (which is well within the uncertainty in this new value). That's a lot different than the 61 km/s/Mpc they got in that Triangulum Galaxy paper.

I don't think you've got to forget what you memorized quite yet, ivy.

Edited by Startraveler

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I don't think you've got to forget what you memorized quite yet, ivy.

Oh good, cause honestly, despite ten years in geology, I never did get it down to the point where I didn't have to grab a chart to clarify ages. I'm still trying to get used to Mississippian and Pennsylvanian rather than Carboniferous.

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