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nebularain
2003-Jan-10, 03:58 AM
This finding suggests the minimum age of the universe is pushed back from 10 billion to 11.2 billion years.

http://dsc.discovery.com/news/briefs/20030106/universe.html

DoctorDon
2003-Jan-10, 05:33 PM
That's a strange turn of phrase in the article: "The universe is at least 1.2 billion years older than previously thought..."

But the current thinking is that the universe is 14.1±0.6 billion years. Moving the minimum age from 10 to 12.2 billion years has no effect on how old we think the universe really is. So it's still consistent with the standard model.

The rest of the article seems okay, from my admittedly cursory reading of it.

Don

Glom
2003-Jan-10, 05:55 PM
The problem is that right now, cosmologists are having to muck about with this dark energy. It's so conjectural at this point that any conclusions reached by cosmologists at this point should be treated with caution. This is the true unknown.

Wiley
2003-Jan-10, 05:57 PM
If the HST can see galaxies 13 billion lightyears away, one would think the universe must be a least 13 billion years old.

Hale_Bopp
2003-Jan-10, 07:30 PM
Remember, the 13 billion light year distance has not been measured asbolutely. There are definitely uncertainties involved in these numbers. It could be somewhat closer or somewhat farther away. 13 billion is the number that lies in the middle of our "error box" for the measurements..

It used to be that if astronomers got within a factor of 10 of the true value, they would pat themselves on the back. Now we are in the age of what some are calling precision cosomology. That means we think we are off by less than a factor of 2 /phpBB/images/smiles/icon_smile.gif

Rob

John Kierein
2003-Jan-12, 02:56 PM
Or maybe it's 15 to 20 % less than 12 to 13 Billion years. 20% less than 12 is less than 10.
http://www.flatoday.com/space/explore/stories/1999b/060299h.htm

cable
2003-Jan-12, 03:16 PM
On 2003-01-09 22:58, nebularain wrote:
This finding suggests the minimum age of the universe is pushed back from 10 billion to 11.2 billion years.

http://dsc.discovery.com/news/briefs/20030106/universe.html

that's still far below the astronomical US deficit ..... /phpBB/images/smiles/icon_biggrin.gif

Jimi Hendrix
2003-Jan-12, 11:34 PM
I beleive at one point the age of the universe was suposed to be 17 billion years.

Kaptain K
2003-Jan-13, 03:57 PM
On 2003-01-12 18:34, Ritchie Blackmore's cousin wrote:
I beleive at one point the age of the universe was suposed to be 17 billion years.

17 billion years is still within the "range of uncertainty" of current theories.

Muchansclon/Planet 10?
2003-Jan-13, 06:45 PM
From the books i have read, ve learned that the universe is 15-20 billion years old. So that guy who said 17 billion is very close the truth,belive it or not!

JS Princeton
2003-Jan-14, 12:17 AM
There are rather large error bars on the age of the universe. I'd say we have very good evidence for it being at least 12 billion years and no more than 17 billion years. That's probably being very generous with error bars. The age continues to be measured better and better, but it might be very hard to get the last systematics down enough to get a much more accurate age.

David Hall
2003-Jan-14, 09:26 AM
Over the last decade or so the error bars have shrunk considerably though. It used to be anywhere from 10-20 bly. Now I think it's narrowed to about 13-16. And each new measurement, like this one, lops off a few million more. In the past there was a real problem where the best fit for the universal expansion seemed to conflict with the ages of the oldest observed stars (though I believe the error bars have always overlapped), but that's been largely resolved now due to better measurements of both.

John Kierein
2003-Jan-14, 02:24 PM
The age problem for the big bang is very severe and often swept under the rug. I do not believe in the big bang. Stars of an age of 10 to 16 to 20 billion years are found in our galaxy and nearby galaxies. But the problem is compounded by the fact that old stars are seen in the infrared deep sky images. The population of old stars is what makes the spirals show up in the IR. The existence of stars 15 billion years old when they emitted their light billion years ago pushes back the minimum age even farther, much beyond any estimates of the big bang time.

Also, it has been stated by those who believe that quasars do not have an intrinsic red shift, (like I believe), that quasars were all formed at about the same time and are no longer being formed. Quasar red shifts vary from less than 1 to as much as 6, meaning they must live 10 to 15 billion years themselves if this is so. Consider the total ENERGY they have would have to have emitted in this time from a very small space. Not reasonable. How old are the most distant quasars? Why should they be youger than nearby ones? The age problem is one of the most difficult ones for a big bang theory, but not least.

DoctorDon
2003-Jan-14, 02:43 PM
On 2003-01-14 09:24, John Kierein wrote:
The age problem for the big bang is very severe and often swept under the rug. Stars of an age of 10 to 16 to 20 billion years are found in our galaxy and nearby galaxies.


No, it isn't. For a while, people worried that there seemed to be globular clusters that were too old, but those measurements had large systematic uncertainties that were later improved, and the age dropped. This is a non-issue anymore.



But the problem is compounded by the fact that old stars are seen in the infrared deep sky images. The population of old stars is what makes the spirals show up in the IR. The existence of stars 15 billion years old when they emitted their light billion years ago pushes back the minimum age even farther, much beyond any estimates of the big bang time.


I was under the impression that this premise (population of old stars is what makes the spirals show up in the IR) is more accurately stated as "galaxies whose dominant light is emitted in the infrared are dominated by old stars", and is only meant to hold for old, more nearby galaxies, in which all the young stars that would emit in the blue have burned out and gone away, leaving the red/IR stars, which last longer. Those red stars were red when they were young. The whole spectrum of a galaxy shifts to the red as it gets older because the blue stars burn out, not because the old stars get redder.



Also, it has been stated by those who believe that quasars do not have an intrinsic red shift that quasars were all formed at about the same time and are no longer being formed. Quasar red shifts vary from less than 1 to as much as 6, meaning they must live 10 to 15 billion years themselves if this is so. Consider the total ENERGY they have would have to have emitted in this time from a very small space. Not reasonable.


Why not?



How old are the most distant quasars? Why should they be younger than nearby ones?


Because we're seeing the more distant ones at an earlier stage in their development due to the lookback time. I don't see a problem there.



The age problem is one of the most difficult ones for a big bang theory, but not least.


No, not really. New observations may raise it again, but for right now everything adds up. The best measurement on the age that I've heard recently was 14.1±0.6 Gigayears. I don't have a reference; it was in a talk by John Tonry at CalTech. That result combines several independent lines of evidence (like Hubble Key Project), and the error is a rough 1-sigma estimate combining statistical and systematic uncertainties.

Don

John Kierein
2003-Jan-14, 02:50 PM
http://www.nytimes.com/2003/01/14/science/physical/14COLL.html
registration req'd. Good science. But I disagree that it's looking at the big bang.
OK dr. Don. Consider a quasar emitting more enrgy than several galaxies from a size smaller than the sun. Now have it continue to do this for 10 billion years. Now divide by c^2 and see how much equivalent mass was radiated away from this black hole. Is this reasonable??

Spaceman Spiff
2003-Jan-14, 03:45 PM
On 2003-01-14 09:24, John Kierein wrote:
The age problem for the big bang is very severe and often swept under the rug. I do not believe in the big bang. Stars of an age of 10 to 16 to 20 billion years are found in our galaxy and nearby galaxies. But the problem is compounded by the fact that old stars are seen in the infrared deep sky images. The population of old stars is what makes the spirals show up in the IR. The existence of stars 15 billion years old when they emitted their light billion years ago pushes back the minimum age even farther, much beyond any estimates of the big bang time.

Also, it has been stated by those who believe that quasars do not have an intrinsic red shift, (like I believe), that quasars were all formed at about the same time and are no longer being formed. Quasar red shifts vary from less than 1 to as much as 6, meaning they must live 10 to 15 billion years themselves if this is so. Consider the total ENERGY they have would have to have emitted in this time from a very small space. Not reasonable. How old are the most distant quasars? Why should they be youger than nearby ones? The age problem is one of the most difficult ones for a big bang theory, but not least.


Again, you speak of which and criticize that you know next to nothing about.

What, do you think that astronomers are in the business of just making things up that aren't consistent with the laws of nature? You just make up what you think you know about quasars (mix in a little that you read about them 30-40 years ago) -- much of it just plain nonsense -- and then tell the rest of us that the present quasar model is nonsense. And then you conclude that we must be off our nuts to hold such a model.

First off, quasars aren't as small as YOU SAY they are. Here is what I said in the topic "New Distant Quasars":

----
In the present quasar paradigm supported by observations (as you say -- light variability arguments), the supermassive black hole has a size equivalent to its Schwarzschild radius (which can be spherical, if not rotating, or flattened in shape if it is rotating, but nevermind), and this is:

R_sch = 3 km * (M/Msun)

And if M = 1 billion solar masses (it ranges from a few hundred million to several billion in quasars), then just the Schwarzschild radius is 3 billion km. This takes you to 20 AU or nearly the orbit of Uranus. (So much for very much smaller than Earth's orbit or the size of a star). Now the continuous emission of light that spans from the infrared, optical, ultraviolet, and X-rays is emitted by gas in the vicinity of and in the process of being accreted (and/or ejected) by the black hole. The minimum stable orbit is something like ~3 R_sch, and so then we're talking about 60 AU in radius. X-rays generally show the strongest and most rapid variability and so are likely emitted by gas nearest the black hole. However, the restframe UV light that makes quasars so bright at optical wavelengths (due to their redshifts) is emitted by gas at a few 10s of R_sch, and in that case we are speaking of a few hundred AU -- corresponding to out into and beyond the Kuiper belt in size. These size scales are predicted theoretically and consistent with variability studies.
----

Second, nobody (except you) says that quasars last the full ~11 billion years corresponding to the redshifts over which they are found (0.1 - 6.4). In fact there is strong observational evidence against this, and in fact that same evidence indicates that that a typical quasar lifetime is probably just ~100 million years. Now, in some cases, the quasar epoch of a galaxy may be episodic (turn on during formation, then off after the gas supply has shut off, then on again after a major merger event).

That the quasar phenomenon existed between 13 and 2 billion years ago is not to say that this was a constant phenomenon. We OBSERVE that quasars were rare at the very largest redshifts, they were prominent between redshifts of 2 and 3, then rapidly declined toward the present time, and became extinct as of 2 billion years ago. Not too suprisingly, since the quasar phenomenon is observed to lie in the nuclei of massive galaxies, this evolution of the quasar population tracks the observed star formation rate in galaxies.

Next, the quasar's luminosity depends upon the mass accretion rate, and most quasars can get by with 1 - 10 solar masses per year falling into the black hole:

L = 0.1 * mdot * c^2, where mdot is the mass accretion rate in kg/s, c is the speed of light in a vacuum, and the 0.1 is the 10% efficiency of black hole accretion to convert matter into energy (or gravitational potential energy into light energy).

Over a 100 million years the total energy radiated is something like 10^63 ergs at a luminosity near 10^47 ergs/s. That corresponds to ~1 trillion suns emitting a solar luminosity over 10 billion years. The total mass accreted corresponds to a whopping 0.1% or less of the total luminous mass of a massive galaxy. Big deal.

The current model and paradigm for the quasar phenomenon is fully consistent with observations, physical laws of nature, AND every scientific theory that it impacts - including big bang cosmology. If it failed any of these, we would have some other model for quasars. That goes for the future, too.



<font size=-1>[ This Message was edited by: Spaceman Spiff on 2003-01-14 10:48 ]</font>