Age of Universe Derived

HaeMaker writes "The age of the universe has been calculated to be 12 Billion years +/- 10%, and the Hubble Constant (the rate at which the universe is expanding), is 70km/s/Mparsec.... or in other words, for every Megaparsec (3.26 Billion Light Years) an object is away from us it is moving 70km/s away from us. So, if a galaxy is 2 megaparsecs away, it is moving at a speed of 140km/s away from us. Here is NASA on the subject. "

Comments

Slight error in post.

[Gruuk]

Just a small correction: a megaparsec is 3.26 million light years, not 3.26 billion.

Take it with a grain of salt..

[Ex-NT-User]

It seems that every few years some new group of researchers "discovers/calculates" the age of the universe. And everytime they recalculate it the universe seems to get older by a few billion years. So I would take this latest calculation with a grain of salt, 'cause I'm certain that in a few more years someone is gona claim that it's 13+ billion years old.

Ex-Nt-User

Re:Age of universe

[GrenDel Fuego]

Has anyone ever wondered what's at the edge of the universe?

Socks. A whole lot of non-matching socks..
And pens.

And.. uhm... Jimmy Hoffa.

Star Wars part of our universe?

[William Wallace]

Here's a quote from the article (no joke):

"Alternatively, the universe is pervaded by a mysterious 'dark force' pushing the galaxies farther apart, in which case the Hubble measurements point to an even older universe."

Damn that Darth Vader...

The Hubble Constant and Ideology

[Aravaipa]

It is quite interesting how this long and rancourous debate over the Hubble constant highlights the still non-zero tendency of ideology to intrude into science. For many years their were two main camps of astronomers working on this problem. One camp invariably found a value of around 50 km/s/Mpc while the other group always seemed to come up with 100 km/s/Mpc. The real howler was in the uncertainties which were usually quoted as +/- 5 or so. It doesn't take a supergenius to realize that something was not quite right here. Thankfully, this somewhat embarrassing rift in astronomy history appears to be closing due to the featured work of a third group headed by Wendy Freedman. Eventually science self-corrects for ideology, and therein lies the secret for its progress.

Probably the most amusing aspect of this history is that for all these years the number quoted in the textbooks was usually 75km/s/Mpc. Not because a large number of measurements yielded this value, but because it represented a compromise between the 50 and 100 camps. Turns out that number wasn't far off after all!

Once again the old tale

[Ektanoor]

I respect the weight of NASA. It is a great institution that gave a large contribution to present human knowledge. However I cannot respect its tendency to make History out of some pieces of dust.

The so-called "Age of the Universe" is something I would call rather childish. At least, in the way they show the public these things.

Maybe we can determine that such metaformations such as our "Universe" could carry an age. However we must look at two major problems when we face such things.

We don't know all factors that determined the formation of the "Universe". Recent Hubble discoveries even had risen a lot of questions on whether old ideas or hypotesis are correct at all. Not long ago there was a little squirmish about Hubble's constant itself. Not to count on such things as finiding galaxies near the "edge" of the Universe.

Do we know the Universe? Aren't we missing anything? Up to the last century many people were convinced that the World and subsequently the Universe were not older than 6000 years. In fact this belief, based mostly on the human experience of something called "civilization", was proved wrong. Today this same civilization possesses a wider reaching eye and manages to see things supposedely 12 billion years old. However beyond that "eye" there might be a lot more. Besides it seems that this "eye" possesses some short-sightness due of a strong belief that it can't be wrong.

Re:Dark Matter/Missing Mass?

[astroboy]

The measures of the Hubble constant include dark matter; the Hubble constant comes from the total amount of mass in the universe, so anything that interacts gravitationally is included. Dark matter is the stuff that seems to have mass but isn't `glowing' like stars, so can't be seen; it's in there. These measurements don't discriminate between different forms of mass.

The Cosmic Micrwowave Background (CMB) definately does contribute to the mass/energy density of the universe, as you say. However, it's effect is tiny. 3K radiation corresponds to an energy density of ~(kT) ~4x10-23 J/m3, vs. on the order of 10-19 for Omega=1; so the CMB contributes about 10-4. In earlier, hotter times, the CMB contributed more; but in this cold epoch, not so much.

FWIW: This is a NASA announcement, to sort of trumpet the end of their 10-yr `Key Project' using the Hubble Telescope. A lot of good work's been done by the Key Project Team, but the announcement isn't exactly news to working cosmologists; the number has been converging to this for a while.

Re:Is earth in the former center of the universe?

[AstroJetson]

Doppler/Red shifting is always caused by a difference in speed. So the further away an object from earth, the faster it moves relative to earth.

Red shifting can also be caused by gravity. As light travels up through a gravity well, it gets red shifted by the time dilation. From the perspective of a distant observer, time slows down inside a gravity well.

Your other question was handled by the balloon analogy, but I'd like to add something. This type of misunderstanding arises from assuming that all the stuff in the universe was once contained in a very tiny volume and then exploded into a previously empty universe. This is not what the big bang theory states. It states that the universe itself was contained in a tiny volume. It's a subtle but important difference.

g

12 billion years is probably a lower limit

[tim pickering]

the hubble constant is only one of the parameters you need to calculate the age of the universe. the overall mass density (commonly expressed as q_0 = mass density/critical density for collapse) and the cosmological constant (if any) are also needed. the 12 billion years is derived assuming the mass density is equal to the critical density for eventual collapse (a flat universe; q_0 = 1) and no cosmological constant. however, we don't really yet know what the values for these other parameters are, even to within a factor of two. current best estimates favor q_0 less than 1 and a nonzero cosmological constant which can result in ages of 15-20 billion years or more for the universe.

the hubble constant is a hard thing to measure right and it's taken decades of work to get it to within 10%. measuring q_0 and the cosmological constant to a similar precision is decades more away, i think.

tim (i'm not a cosmologist, but i play one at work)

Re:12 billion years is probably a lower limit

[EricWright]

To comment on the previous post... this isn't technically correct.

Capital omega (you try typing one) is the ratio of the overall (mass + energy + cosmological) density divided by the critical density (remember, mass IS energy, E=mc^2). In a flat universe, Omega = 1; closed, Omega > 1; open, Omega 1.

Open means the universe will expand forever, with no limit on the physical size. Flat means the expansion will slow to zero in an infinite amount of time, producing a finite physical size to the universe. Closed means self-gravitation of the universe will win out, halting the expansion of the universe, and causing it to re-collapse, presumbly into a "Big Crunch".


The baryonic matter (massive particles such as protons, neutrons, etc.) and photons (light/energy) are all the stuff we see, and is though to have density of about 0.1-0.3 of the critical density.

The cosmological constant (the was invented, then abandoned by Einstein) is a mathematical embodiment that the "vacuum" of space is not actually empty, but full of energy fluctuations that create particle/anti-particle pairs, which annihilate each other in an incredibly short amount of time. This "zero-point" energy would add to the total mass/energy of the universe, and increase the density.

q_0 is the deceleration parameter, equal to 1/2 for a flat universe. If q_0 > 1/2, the deceleration rate is greater, and the universe is closed. If q_0
The current theory is the the density of baryonic matter and light/energy (Omega_b) and the contribution of the cosmological constant (Omega_Lambda) add up to exactly equal the critical density, Omega_total = 1.

Eric (who just finished a stint as teaching assistant for a class in astrophysics and cosmology).

what is being neglected here

[sporkboy]

...is that the time (and thus the universe) began on January 1, 1970. It will end in 2038. Don't believe the non-Unix pseudoscience.

So, according to the article, we're still guessing

[spun]

Combining Hubble's constant measurement with estimates for the density of the universe, the team determined that the universe is approximately 12 billion years old -- similar to the oldest stars. This discovery clears up a nagging paradox that arose from previous age estimates. The researchers emphasize that the age estimate holds true if the universe is below the so-called 'critical density' where it is delicately balanced between expanding forever or collapsing. Alternatively, the universe is pervaded by a mysterious 'dark force' pushing the galaxies farther apart, in which case the Hubble measurements point to an even older universe.

The emphasis is mine. Is it the media or the scientists that make these proclamations seem so cut and dried, like, "whew! now that's settled!" when in fact, there is so much guesswork, any conclusion is just not certain? I think it's the scientists, but they should know better.