Well, I hope I don't make this too long, but sometimes I just get carried away. one of the "against the mainstream" topics hanging around some of the discussions is "young earth creationism", the idea that the earth is a mere 10,000 or so years old. It is a preposterous notion, and the attempts to make it look "scientific" are, for the most part, no less preposterous. I will leave off from discussing geology & the age of the earth specifically, as outside the scope of this board. However, young earth creationists don't just think that the earth is a mere 10,000 or so years old, but that the entire universe is equally young. That does bring in astrophysics, and that's where I want to go.

I will try to present a brief outline of the astrophysical & cosmological determinations of the ages of objects in the universe. It's necessarily short, just to keep from overwhelming the board, but will hopefully carry enough references to satisfy those interested in extracurricular reading.

Stellar Evolution

The basis for deriving the ages of the sun & stars, is the theory of stellar evolution. Unlike biological evolution, where individuals don't "evolve" but populations do, stellar evolution actually refers to the life cycle of individual stars.

I don't propose to write an exhaustive survey of stellar evolution here and now, there are a few million pages of material available on this very broad topic. Suffice to say that stellar evolution amounts to the extraordinarily complicated application of extraordinarily simple physics to the problem of how the structure & appearance of a star will change with time.

Very basically, all main sequence stars are stabilized by the process of fusing hydrogen into helium, and the rate at which they do this depends on the central temperature of the star. The hotter the temperature, the faster hydrogen "burns" into helium. The core temperature is dependent on the mass, so more massive stars get hotter inside, use up their fuel more quickly, and live shorter lifetimes.

By throwing all the ingredients into a computerized recipe, we can calculate what the surface of a star would look like, depending on it's internal structure. We can allow the model to progress through time, and compare the changing surface appearance as a function of time with visible stars (of which there are a lot), and hence derive the age of a star given enough knowledge (color, brightness, mass, spectrum, etc.). It's even easier to compute the age of a cluster, via its color-magnitude diagram (CMD, also known as the Hertzsprung Russell diagram).

That's all I'll say about that for now, if you want to know more, hit the books. For general readers, the books by James Kaler are the best, and surprisingly informative (Stars, Extreme Stars, and Stars and their Spectra are my favorites). For big, tough, physics dudes (and dudettes), who want only the real stuff, there are plenty of books for you too. My recommendations would be Stellar Interiors - Physical Principles, Structure and Evolution, C.J. Hansen & S.W. Kawaler, Springer (A&A Library) 1994, and Advanced Stellar Astrophysics, W.K. Rose, Cambridge University Press, 1998. And don't forget the timeless classics, the books that define the science of stellar evolution; The Internal Constitution of the Stars, Sir A.S. Eddington, 1926; An Introduction to the Study of Stellar Structure, S. Chandrasekhar, University of Chicago Press, 1939, and Structure and Evolution of the Stars, Martin Schwarzschild, Princeton University Press, 1958. Maybe I go overboard with the books, but creationists forever like to complain about how "unscientific" is everything they don't believe. So tell them to go read a book.

Age of the Sun

The one star we can see up close & personal is the sun. We know more about it than any other star. And, thanks to the relatively recent science of helioseismology (which I won't get into either), we know a lot about it's internal structure. From that we can determine the age of the sun with greater precision than any other star, by application of stellar evolution theory to our observations of the sun's appearance and internal structure. The current best estimate of the age of the sun is 4.66±0.11 billion years (Helioseismology and the solar age, W.A. Dziembowski et al., Astronomy and Astrophysics 343(3): 990-996, March 1999; Are standard solar models reliable?, J.N. Bahcall et al., Physical Review Letters 78(2): 171-174, January 13 1997)

Age of the Galactic Disk

The sun is but one of the many stars that make up the disk region of the Milky Way. Since the sun is obviously made up of material already cycled through at least on previous generation of stars, we expect that the oldest disk stars should be rather older than our own sun. We can place limits on the age of the Galactic disk by deriving the ages of well observed individual stars, from the CMD for open clusters in the disk, or by using models of how long white dwarf stars take to sit there and cool off.

Studies of the Galactic disk conform with expectations. Liu & Chaboyer find the oldest field stars in the Galactic disk to be 9.7±0.6 billion years old. The oldest white dwarfs in the Galactic disk are of comparable age, 8±1.5 billion years according to Leggett et al., and a compatible 9.5 billion years, according to Oswalt et al. (A lower limit of 9.5 Gyr on the age of the Galactic disk from the oldest white dwarf stars, T.D. Oswalt et al., Nature 382(6593): 692-694, August 22, 1996; The cool white dwarf luminosity function and the age of the galactic disk, S.K. Leggett SK, M.T. Ruiz & P. Bergeron, Astrophysical Journal 497(1): 294-302, Part 1, April 10 1998; The relative age of the thin and thick galactic disks, W.M. Liu & B. Chaboyer, Astrophysical Journal 544(2): 818-829, Part 1, December 1 2000).

Globular Cluster Ages

Globular clusters should harbor the oldest stars in the Galaxy. Observation bears this out. Studies of globular cluster ages via their CMD consistently turn out ages in excess of 10 billion years. The recent success of applying the white dwarf cooling models to globular clusters (difficult because the clusters are very distant and the white dwarfs very dim) returns similar values.

A few familar examples follow. The best derived age for the globular cluster 47 Tucanae is 13±2.5 billion years (The white dwarf distance to the globular cluster 47 Tucanae and its age, M. Zoccali et al., Astrophysical Journal 553(2): 733-743, Part 1, June 8 2001). A best fit age for M92 is 14.5 Billion Years (A distance-independent age for the globular cluster M92, F. Grundahl et al., Astronomical Journal 120(4): 1884-1891, October 2000). And Omega Centauri can be no younger than 10.06 billion years (Theoretical uncertainties in the subgiant mass-age relation and the absolute age of omega Centauri, B. Chaboyer & L.M. Krauss, Astrophysical Journal 567(1): L45-L48, Part 2, March 1 2002; Cluster ages experiment: The age and distance of the globular cluster omega Centauri determined from observations of the eclipsing binary OGLEGC 17, I.B. Thompson et al., Astronomical Journal 121(6): 3089-3099, June 2001).

And it's not just a few (although a few will do). D.H. McNamara observed 16 globular clusters, with an average age of 11.3 billion years (The ages of globular clusters, D.H. McNamara, publications of the Astronomical Society of the Pacific 13(781): 335-343, March 2001).

And it's not just Milky Way globulars. We can make CMD's for globulars around other galaxies. Beasley et al. observed 131 globular clusters around the giant elliptical NGC 4472, and derived ages for two populations of globulars, metal poor (14.5±4 billion years), and metal rich (13.8±6 billion years) (Ages and metallicities of globular clusters in NGC 4472, M.A. Beasley et al., Monthly Notices of the Royal Astronomical Society 318(4): 1249-1263, November 11 2000).

End notes

There. I could have cited far more papers than that, the literature is awash with age determinations. All based on phyics applied to stars. I won't bother with cosmology, except to say that totally independent ages for the universe, derived from the acoustic spectrum of the CMB, run in the range of 13-15 billion years. That's compatible with the more precise globular cluster ages, even though totally independent in derivation.

So why have I carried on so? I just want to make the point that "young earth" or "young universe" creationism is strongly counterindicated by some very strong physics. It's not enough to demand that biology be tossed out the window, along with geology and the physics of radiometric dating. It also requires that astrophysics & astronomy are totally false.

That goes way beyond "against the main stream" to something more akin to "against all knowledge".

I figure, if anyone wants to hang around and debate the age of the universe, they should be obliged to explain why astrophysical ages are all wrong.

Good Night.

What you're missing is that the YEC don't even believe in physics, so using physics to prove the extreme age of the universe is pointless.

Nice post, though. [img]/phpBB/images/smiles/icon_smile.gif[/img]

Of course, a YEC might explain all this away by saying that God created the universe with the appearance of age. This is technically possible for God to do, but it likely takes us out of the arena of Science and into theology: Would God do such a thing?

I keep trying to tell everyone, from personal experience, that the only way to convince a YEC that their belief in a young Earth / universe is wrong is to speak their language! Explain to them how the literal six "twenty-four hour" time slots in Gen. 1 (for that is what they cling to) is a complete misinterpretation - make them question the interpretation of what is written without threatening or challenging their belief in a creator. Then they will be open and willing to listen to what you have to say. Try it! (And if it doesn't seem to be working, refer them to me, and I'll straighten them out for you. [img]/phpBB/images/smiles/icon_wink.gif[/img] )

__________________
"As I lay beneath the Southern Cross, the stars tell more than I could" . . . David Meece

The problem is that many YECs refuse to admit any non-literal interpretations of the Bible (except when waving away certain inconsistencies). They seem to fear a "slippery slope" wherein if you say, "this part of Genesis is metaphorical", soon you're flatly denying everything else in it.

Personally, I think that's a rather brittle version of faith. You then have to twist every empirical finding to fit this literalist framework, and you wind up pledging to fit the truth to your belief. For example, if you join the ICR (Institute for Creation Research), you have to sign a statement that the Bible is literally inerrant, and then you have to make all of your "research" fit that.

Reminds me of how the Soviets hammered plant genetics into fitting the good Marxist mold. That little adventure only cost them several million deaths from starvation.

I worked with an engineer who subscribed to the "Omphalos" (appearance of age) idea, i.e., that everything was created X thousand years ago with the precise initial conditions to match the appearance of the ~15Gy old universe. He was a smart guy, and he didn't say it was scientific. I don't really have a problem with that, as long as it's not pushed in a science class.


<font size=-1>[ This Message was edited by: sts60 on 2002-06-27 08:25 ]</font>

Not only that, but they also refuse to admit other literal interpretations for the numerous Biblical creation accounts! (old-earth being one of many)

Well, I learned. (Hurray for me!) It helps to realize the account is a poem - and scientific thinking and describing of events didn't exist until the late Middle Ages / early Rennaissance era, so it doesn't make a whole lot of sense to interpret it that way. Of course, then again, it did take me about a full semester to come around. [img]/phpBB/images/smiles/icon_rolleyes.gif[/img] Hoo, boy.

__________________
"As I lay beneath the Southern Cross, the stars tell more than I could" . . . David Meece

Here is how I resolve this:

How do I know that everything was not created 1 second ago? Maybe all my memories of my life were created on that same second. Maybe all the light and sound reaching me was created in transit in that same second.

If that is true, than who can blame me for being fooled into believing that I really did live all those years?

So if God created a universe 10,000 years ago that appears to be billions of years old, then can he blame me for believing it to be billions of years old?

So, I'll believe what I see and if it is illusion, so be it.
--Tommy
http://www.tommyraz.com

Good luck my friend.

My less lofty goal is just to keep other people from being drawn in to the supposed 'logic'.

Well, just so this thread doesn't remain as merely a bunch of non-Creationists talking to each other and patting themselves on the back, I'll jump in. I generally ignore this type of thread, because I know it's really a waste of my time since no-one who is already committed to a non-Biblical stance on the universe is likely to listen to a Biblical stance, but this thread is so boringly monotonous as yet that it needs a bit of the opposing viewpoint to pep it up.

First, Tim, thanx for classifying stellar evolution as a theory. So many people forget that little detail, or the actual definition of the word theory. Anyway, as support for your theory, you'll be happy to give two or three examples of stars that have evolved exactly according to that theory, with documentation, won't you? Thought not.

Stellar evolution looks at all the different types of stars that we see, and hypothesises that there must be some overarching explanation for why this one is a red giant and that one is a yellow near-dwarf. The theory 'explains' that there is a progression from one to the other, with all the other variations either along the way or as minor offshoots from the 'main sequence'. Yet we have exactly zero evidence that any star has ever changed states along this so-called sequence. The red giant stars that we see today have always been red giant stars for as far back as we have observational accounts; likewise, the sun is exactly the same today as the earliest descriptions of it we have. It's never gotten larger nor smaller, brighter nor dimmer, redder nor greener. Ditto for all the other varieties.

Yes, we have stars that do change: we call them novas and supernovas. But these changes are all we see, we do not have any evidence that any star has ever followed the 'main sequence' or any standardly-accepted offshoot thereof. The idea that there must be some sort of explanation that derives one stellar type from another is strictly an imaginative creation that isn't called for by the known facts.

And Nebularain, while there are certainly a lot of liberal and/or secular interpreters who support your contention about the interpretation of 'yom' in Genesis 1, it remains that only by begging the question can they support that argument. There is no proof, or even realistic argument, that 'yom' there means anything other than a 24-hour day. The liberal interpretation came about solely to try to find Biblical support for modern evolutionary theories; since the Bible doesn't support evolution in any form, the words have to be twisted in order to make it appear to do so. Hence, the creation of the "Age-Day" theory for those who want to have their cake and eat it, too.

Xriso, you'll be able to clarify that remark about "numerous Biblical creation accounts," I'm sure? There's only one account in the Bible of creation, Genesis 1. I realise that there are plenty of people who try to make hay over the supposed inconsistencies between the "two accounts" in Genesis 1 and 2, without realising (or perhaps, ignoring) that Genesis 2 isn't an account of creation but of God's dealings with the first human couple. The only creation detail in Genesis 2 is the specific creation of Eve, which was glossed over in Genesis 1 as being included in the overall creation of mankind.

And Traztx, is God to be blamed because mankind invents theories that require billions of years to work out, when the evidence of the stars themselves in no way requires such theories? God created the stars as they are; men look up at them and, desiring to deny God, make up a story about how the stars must have been formed through a multi-billion-year process. But other than the so-called end results of that process, there is no evidence of the process itself. And the end results--the stars, the planets, the nebulae, etc.--don't require that one particular process to be here. So blaming God for the "appearance" of billions of years, when it was men who created the perception of a need for billions of years in the first place, is rather naive.

Okay, I'm done. You may commence firing.

The (When I consider thy heavens, the work of thy fingers, the moon and the stars, which thou hast ordained) Curtmudgeon

Curtmudgeon, if you dismiss stellar evolution you must dismiss pretty much all of physics because the foundation of stellar physics is basically F=ma.

Stars do not change fast as you point out, therefore forces in stars balance. The forces are (mostly) gravity and internal pressure. The energy for the internal pressure comes from thermonuclear reactions (this is the fundamental step. And the evidence for nucleosynthesis in the Sun is now overwhelming). Thermonuclear reactions change the chemical composition. The change of chemical composition in the core makes the star evolve.

Sure this model is not directly testable in a lab. Sure different type of stars may be completly unrelated. But the evidence is not just the different stars you see with some arbitrary link invented to make it look good. Stellar models explain and reproduce well stellar pulsations, the abundance correlations, stellar winds, explosive events, cooling curves of white dwarfs, for example, across many varieties of stars without fudging the physics. This theory does surprisingly well given its simplicity.

Stellar evolution can be discounted like everything else in the world but it is firmly established in very basic science.

<font size=-1>[ This Message was edited by: frenchy on 2002-06-27 16:30 ]</font>

Curtmudgeon: if one continuous observation were required, we wouldn't be able to know that giant redwood trees grow from redwood seedlings. I don't recall who (was it To Seek?) who said that no one has ever really seen a tree grow.

Silas

Pow pow pow!!!

So are saying you choose to ignore the preponderance of scientific evidence that does not agree with the literal translation of the Bible in favor of the literal translation that is supported by no* scientific evidence?

*No is my word choice, but substituting 'very little' or 'some' would not change the meaning of my question.

<font size=-1>[ This Message was edited by: beskeptical on 2002-06-27 16:53 ]</font>

Thanks for the contrarian viewpoint, The (it's only interpretation if I call it interpretation) Curtmudgeon.

By the way, how do you know your parents were really your parents? That's just a theory... and you weren't there to observe the process take place, were you?

Just teasing...

A question for Dr. Tim...

Has anyone ever estimated how much of the Sun (or rather, the nebula that produced the Solar System) was primordial material, how much was contributed by 1st-generation stars, how much by 2nd-generation stars, and so on? Or is there any distinction between first- and subsequent-generation material?

Not that it matters much; I'm just curious.

With all due respect to Silas, this doesn't invalidate The Curt's point. The seedling-to-redwood link is strengthened by such observations as "There was a seedling right here and now the seedling's gone and there's a redwood in the same place." I believe The Curtmudgeon is referring to this type of observed change, not "one continuous observation."

After all, when you look in a desk drawer and see a pile of paper-clips of different sizes, do you conclude the little ones must grow into big ones?

__________________
SeanF

"Ask to understand, but don't challenge unless you have the knowledge."--NEOWatcher

The contents of this post are ©2008 by SeanF and may not be copied or retransmitted in any form without the express written consent of SeanF

My opinion: I wouldn't blame God for anything man invents. If man invents a theory that corresponds to data, then blame the data. If the theory did not correspond to data, then the theorist is at fault due to error or some other intention other than seeking the truth (fame? control?). If two theories explain the same data, then also look at why one was chosen over another.

I don't see how such a story would in itself be a denial of a divine creator. Multi-billion is really big, but still finite and does not explain the first cause. However, it would be a denial of other stories that other men wrote into the scripture. It would propose that such stories are false.

But there is a process going on and some of it can be observed. The process of nuclear fusion, for example. We can detect the energies and by-products from the sun that correspond to the energies and by-products of fusion in laboratory experiments. Sure some other process might produce the same data, but it is reasonable to suggest that fusion is occuring in the sun.

I agree. Unless there is a way to get to data that eliminates some possible processes, you don't really know which is the actual one that happened.

Agreed, except that I would change the phrase "created the perception" to "observed evidence".

-Tommy

Didn't PhD Creationist Relativists like Russell Humphreys ("Starlight & Time") and Gerald Schroeder ("Genesis & the Big Bang") show that a 10,000 year universe is not incompatible with a 10 billion year one, just as Relativity compels us all to accept Geocentricity to be an equally viable model of reality?!

(Note: My own theological belief is that the standard scientific explanation for the Universe is correct, but that the Universe was created by a Divine Being to follow those "rules")

I'm going to have to respecifully dissagree with you Curt. The accounts