Slashdot Mirror
Carbon Dating Gets an Update
ananyo writes "Climate records from a Japanese lake are set to improve the accuracy of carbon dating, which could help to shed light on archaeological mysteries such as why Neanderthals became extinct. Carbon dating is used to work out the age of organic material. But the technique assumes that the amount of carbon-14 in the atmosphere was constant — any variation would speed up or slow down the clock. Since the 1960s, scientists have started accounting for the variations by calibrating the clock against the known ages of tree rings. The problem is that tree rings provide a direct record that only goes as far back as about 14,000 years. Now, using sediment from bed of Lake Suigetsu, west of Tokyo, researchers have pushed the calibration limit back much further. Two distinct sediment layers have formed in the lake every summer and winter over tens of thousands of years. The researchers collected roughly 70-meter core samples from the lake and painstakingly counted the layers to come up with a direct record stretching back 52,000 years. The re-calibrated clock could help to narrow the window of key events in human history. Take the extinction of Neanderthals, which occurred in western Europe less than 30,000 years ago. Archaeologists disagree over the effects changing climate and competition from recently arriving humans had on the Neanderthals' demise. The more accurate carbon clock should yield better dates for any overlap of humans and Neanderthals, as well as for determining how climate changes influenced the extinction of Neanderthals."
The problem is that tree rings provide a direct record that only goes as far back as about 14,000 years.
What's the problem? That's 7,984 years before the beginning of time.
Sheesh, evil *and* a jerk. -- Jade
...they dominate U.S. politics!
:]
Holy crap. "Painstakingly" doesn't even begin to cover counting 52,000 stripes in a core sample.
Aren't you curious what God was up to before genesis? I mean, if God has existed forever, and the universe is just 6000 years old, then what the hell was he doing all the rest of that time? Off making other universes? Were they successful or not? How much baggage does God have? Are the angels the result of those previous geneses? If not, when were the angels created? And the cherubs, oh why won't anyone think of the cherubs?!
The theological implications of this new science are infinite and staggering.
Science is all about firing a drunk pig out of a cannon just to see what happens.
Maybe if you knew what a half life was you wouldn't find it so confusing?
It may not be perfect but Carbon Dating makes the blurry less blurry and this latest development sharpens it further.
The half life of carbon-14 is only about 5000 years. So either other, unstable isotopes have been degrading into carbon-14:
in which case you should have science to back up those rates of isotopic altercations- or your science is bunkum.
You must be thinking about carbon-5. Carbon-14 is guaranteed for 14,000 years.
Sheesh, evil *and* a jerk. -- Jade
Wouldn't the amount of C-14 have been the same for humans and Neanderthals at any given time? Therefore while we may be unclear exactly when they went extinct (presuming Bigfoot is not a surviving branch of Neanderthals), we should have a pretty good idea in the overlap. Unless they use different dating methods for different events, this really shouldn't change the general picture.
I'm amazed that they found a clear seasonal pattern in a lake going back 52,000 years. Lakes are short lived structures, geologically speaking and 52,000 years is quite far into the last ice age. I guess the lake somehow managed to avoid being glaciated and managed to avoid being washed away by the melt waters. Impressive! I haven't located an ice age map of Japan so I don't know how much, if any, of Japan was actually covered by ice. It is far enough North but the ice sheet was not uniform. (Parts of Alaska were ice free)
I'm not sure what you're trying to imply here. What "they want" is the most accurate answer our CURRENT tools can provide. And as the margin of error of the tools gets reduced over time, they measure again. Trying to narrow down our accuracy doesn't exactly scream "hidden agenda" to me.
Christ! I can appreciate the desire to really dial in our techniques, but expecting that after only about a half a century of refining these techniques that we know the difference between 10,643 and 10,633? We're impressive creatures but it sounds like you're holding out for Doctor Who to swing by and show you history.
Really, it's the best tool we've currently got, and you don't throw out the best tool you've currently got in favor of eyeballing it. Looking at the current margin of error and throwing carbon dating out is throwing the baby out with the bath water.
The problem isn't just that C-14 isn't a constant over time.. It's varies over different parts of the planet. How does there lake account for that?
Maybe if you knew what a half life was you wouldn't find it so confusing?
His comment doesn't show that he doesn't understand the concept of a half life.
I'ts a superficialy reasonable question - if we know that C14 is decaying then it must of come from somewhere.
But his error is to assume the only place it could have come from is the decay of something else.
In fact it's generated by cosmic rays hitting Nitrogen, a beta particle (electron) is captured by N14 giving C14.
Watch this Heartland Institute video
Excuse me while I register a domain name...
Damn, already taken.
systemd is Roko's Basilisk.
The last magnetic reversal of the poles was 780,000 years ago, 720,000 years before carbon 14 dating is useful. I doubt it has any effect.
If only we had objects with known dates, this wouldn't be a problem, as you could compare directly. The best would, of course, be some kind of annual layers, so you could count how old they are. Oh, if only there was some method or another that worked that way.
Besides, I don't really think an event that last took place 780,000 years ago is going to affect a dating method where only traces too small to be measured exist after 100,000 years.
This is Slashdot, where the uninformed gather to demonstrate their superiority by scoffing at every scientific advance. The ones they don't understand they just dismiss as impossible.
systemd is Roko's Basilisk.
It's not that bad. Carbon14 dating does have a sound scientific basis and is ballpark correct. However there is sufficient variation between labs that it's clear the measuring process itself is not precise and, worse, there are clear systemic differences between C14 dates and dendrochronology. It's not clear what causes this - variation in C14 over time? over different regions? different rates of decay? - so anything which helps reconcile the figures is good.
...strudents are slacking here. Get back to your work. Recount!
Yes, that is why it is so convenient when they find coins with stamped dates like "70 BC" on archeological sites!
Jupiter having moons has nothing to do with distances.
"Hot lesbian witches! It's fucking genius!"
The Internationally agreed Radiocarbon calibration curve (IntCal) - co-ordinated from Belfast University - takes info from ice-cores, lake sediment cores, tree-rings, corals, etc from the Southern and Northern hemispheres (there's an offset between them) puts them together (this work is done by statisticians using specially developed methods rather than other scientists using off-the-shelf techniques) and although some scientists would rather that only their work was used (as they can then claim whatever 'accuracy' they wish to claim) independent verification of lab practices is extremely useful in the work. The most recent published work dates back to 50,000 years BP ('before present' where 'present' is 1950) and the next set of curves (IntCal 12) - being worked on at the moment will take it back further. Abstract for IntCal 09 - http://eprints.whiterose.ac.uk/10694/
That carbon dating has always been as accurate as you can afford. You decide the date that you need in order to confirm your thesis, send your sample to as many labs or as many times as your budget allows, then pick the closest answer from the essentially random set of results.
Anyone on the inside of the inside care to confirm or refute that?
I'm not on the inside, but I've read some of the papers.
Every few years there is an International Radiocarbon Intercomparison, where a batch of different types of samples are sent to most of the world's labs (~100) to date. The results are then compared. Overall stats are published anonymously, and individual labs can publish their results if they want.
The most accurate method (AMS) shows error rates of ~1%, while older methods give error rates of up to 10%.
Of course there are some classes of samples which present special problems; the study samples are ones which don't present major contamination issues.
The full study from 2003 is open access: here
Not correct, absorbing an electron would not change the atomic number. N14 absorbs a thermal neutron, and C14 decays by beta decay. K capture emits a neutrino.
Fugue for Aaron Swartz
Usually when I see a post moderated as informative, it leads me to believe it may contain information of some kind. I think this would be better characterized as insightful.
If anyone does't understand what the parent is talking about, the half-life of Carbon 14 is 5,730±40 years. That means that 52,000 years is a little more than 9 half-lives. By taking 1/2 and raising it to the power of 9, we can conclude that about 0.2% of the original carbon 14 will remain in the oldest layers of sediment.
As for the question of where the Carbon 14 is coming from, we know that it's formed by cosmic radiation striking the atmosphere, and that the amount in the atmosphere varies slightly from year to year. As this article has explained, the purpose of this research is to get a better idea of how much Carbon 14 was in the atmosphere every year so that we can get a better idea of how old a piece organic matter might be based on it's isotopic ratio (the fraction of the carbon that is Carbon 14).
There are multiple techniques available that can be more or less precise (e.g., regular C-14 dating versus atomic mass spectrometry), and these will inevitably yield slightly different results because of the normal scientific measurement process. But essentially random results and testing until you get the one you want? Uh, no. In fact, one of the clearest demonstrations that the technique is not random is that you can take a series of samples from different layers of sediment, and within the analytical uncertainties of the measurements, they come out in the right chronological order (e.g., deeper samples older than higher samples in the succession of layers). If it were random, no such correlation would be expected to occur.
Only people unreasonably skeptical of the technique, or who have never actually worked with it, would think there aren't other constraints on the results that would test the overall validity. Your "sources on the inside" don't know what they are talking about, or apparently have an axe to grind.
Since the decay of fission products produces thermal neutrons, some of these can be absorbed by the very common N14 to become C14. Above ground atomic tests produced a spike of C14, for example.
Fugue for Aaron Swartz
If you're looking at things that happened more than 10,000 years ago, getting it within a few hundred years is all the accuracy you need. But just thinking about how isotopic ratios are measured, you can see that it would give the most precise measurements near the half life of Carbon 14 (5,730 years) with accuracy increasing from the time the plant or animal died up to 5,730 years and decreasing thereafter. The actual accuracy would also vary by the size and purity of the sample as well as the sensitivity of the instrument used, so you can't really speak in general terms about the accuracy of carbon dating.
Yes, the half-life of carbon-14 is only about 5000 years. After 5000 years that means half the original C-14 remains. After 10000 years, 1/4 the original C-14 remains. After 15000 years, 1/8th. After 20000 years, 1/16th. After 25000 years, 1/32nd. After 30000 years, 1/64th, and so on. Typically, with radiometric dating techniques you can keep on measuring the parent (radioactive/decaying) isotope to daughter (product) isotope until about 10 half-lives have gone by. After that, so little of the original parent radioactive isotope is left, and it is so easy to contaminate the sample with a wiff of modern material, it is tricky to go any further. If you use a really large sample and particularly precise techniques, sometimes you can stretch that a little. For C-14 dating that means the nominal range is about 50000 years. You can stretch a little beyond that if you are careful (I think the max is ~100000 years).
Because the Earth is very old, it's logical to wonder why all C-14 isn't decayed by now. The simple answer to that is: it is being constantly created by cosmic rays penetrating into the atmosphere and generating C-14 from N-14. It is an equilibrium process of generating C-14 and then letting it decay. More importantly, the rate of its generation does vary a bit, and that's what this study (and a lot of other previous studies) have been calibrating. The difference between using the modern-day atmospheric C-14 concentration (technically, the amount of C-14 in the atmosphere before we screwed it up with nuclear weapon testing) and the recalibrated values is about 10-20%, due to the variation in C-14 concentration in the atmosphere over the last 50k years or so.
So, I'm not quite sure what your problem with C-14 dating is, but I think you need to re-evaluate some of the basics of the method. I recommend the wikipedia page as a start.
Reading one of the articles ( http://researchcommons.waikato.ac.nz/bitstream/handle/10289/3622/Hogg%20Intcal09%20and%20Marine09.pdf ) seems to make it clear that the Lake Suigetsu project is a player, but only one of many, in the project to develop a better INTCAL chronology. It may be obvious to some, but any single dataset is not particularly useful until it is corroborated with many others. The Suigetsu project has been at work for several years and, although there has been some revision made to their baseline data, it hardly seems like headline news.
OTOH, it's always great to hear what scientists have been up to, regardless of the field.
This comment was written with the intention to opt out of advertising.
"We have no idea how much carbon14 was around in the past. By assuming anything its just pseudo science. But if we tell the truth then anyone claiming another truth wins so we have to lie."
ACs (C=xtian/Coward? Oh well) are not likely to educate themselves. Should you want to do a Truth or Dare: Do google where C14 comes from. You'll be surprised.
(And don't you really understand counting? Tree ring counting? Varves counting. If you fell a tree, you can count the rings? You can do a C14 determination for each ring? You can use other (older) trees with overlapping age ranges and hence overlapping ring patterns to continue getting values for older ages? You can go on doing that? You can do the same for varies, which is what the Japanese did. And being scientists, they cross-reference such values for various sources. And when you do that real science, all your post is reduced to BS.
Bert
"By assuming anything its just pseudo science."
But assuming your holy book is correct, doesn't make it a pseudo religion, does it? Nope, it is the one true religion. All the other thousands of gods have been made up, but yours is real. Yup.
Two problems.
PHEM - party like it's 1997-2003!
I'm in! Should I bring flowers and candy?
The conversion of Nitrogen to C14 is caused by a neutron http://en.wikipedia.org/wiki/C14_dating. Being not charged, it tends to be rather insensitive to magnetic fields.
Chance that you're religious: above average.
Bert
We have no idea how much carbon14 was around in the past.
If only there were studies that test how much carbon-14 were around and compare the results to other dating methods. And if only such studies would get posted to Slashdot. And if only such studies went back to the 60s, so that the articles, that would be posted to Slashdot if they had existed, could mention some historical context for how long such work has been going on.
lol it sharpens it for what, less than 1% of Earth's history?
Good point, I guess it is useless then, as no one cares about what happened in that one percent of Earth's history. We should stop researching historical writings too, as those cover even less of Earth's history.
Uh, you do know that C14 decays to N14 by emitting a beta particle don't you?
No, the angels were "Version 1.0". After he realized he'd left off a few important bits, like genitals, he created man.
Of course angels have "important bits". Otherwise, how would the sons of God have knocked up the daughters of men (Genesis 6:4), creating the Nephilim and giving God the excuse for the great server wipe of 1656 A.M.?
Don't you know almost every G.I.R.L. on a geek board is a guy in real life? ;-)
if God has existed forever, and the universe is just 6000 years old, then what the hell was he doing all the rest of that time?
Reconciling the six creative days of Genesis 1 with the billions of years of the scientific record is perfectly possible because the creative days in Genesis 1 are not exactly literal. A day is like a thousand years to God (Psalm 90:4, 2 Peter 3:8). Consider that the seventh "day" of God's rest never had its "evening and [...] morning", implying that it is ongoing, and the discussion of God's rest in Hebrews 4 bears this out. We've hashed out day-age theory before on Slashdot.
You're right (well not about the beta particle bit). I misunderstood the misunderstanding :)
So, how do you turn N14 into C14? With a hammer?
There is an account of a lab dating a sample as being 200,000 years old but When they told the CoalMiner the sample came from he was very surprised.
also with any radioisotope dating you can get a rather large spread even in the same chunk of "stuff" (and with the same technique also) this is even Order of Magnitude level differences.
Any person using FTFY or editing my postings agrees to a US$50.00 charge
Hitting an N14 nucleus with a neutron would be the usual method in the atmosphere. Though you could hit C13 with a neutron too amongst other things, but there's a lot of N14 in the atmosphere so that path is the overwhelming mechanism.
"Anyone on the inside of the inside care to confirm or refute that?"
how do you refute nonsense?
While lab shopping does happen, it's onyl good for that ONE event and doesn't hold up over times.
If your thesis runs counter to C14, BUT goes along with current understanding of the field, then you have made a huge discovery. Far more important then the thesis itself.
The Kruger Dunning explains most post on
Are you lost, little one?
Free Martian Whores!
If a day is an era, why are an evening and a morning even mentioned?
The use of "day" in Genesis 1 is an illustration, just as Jesus used illustrations in his ministry.
Following the 7th day, Adam fell into sin and was expelled from the Garden.
What makes you say "following the seventh day", as opposed to the seventh day being the present era?
N14 is 7 protons + 7 neutrons. Add a neutron to that and you've got N15 (7 protons + 8 neutrons).
To get to C14 from N14 you've got to turn a proton to a neutron. (Carbon has 6 protons. C13 has 6 protons and 7 neutrons, C14 has 6 protons and 8 neutrons).
Roughly speaking proton + electron <-> neutron, so
N14 + beta <-> C14
Obviously you could get from C13 to C14 by neutron capture, but that's not what we're talking about here.
or am I dumb?
Not dumb, misinformed. It's
N14 + neutron -> C14 + proton
The decay of C14 to N14 is beta decay, but C14 production isn't the reverse of that - it's a thermal neutron knocking out a proton (well to over simplify).
We'd know for certain whether eating bacon cheeseburgers, sticking our willies up other men's bottoms or wearing a wool sweater with cotton trim is OK.
The Mosaic dietary law worked for its time, protecting the health of the Jews for over a millennium. Though many of the specifics were no longer needed by 33 CE due to improvements in general sanitation, the general principles on which God operates have not changed. True, the way the Judaizer controversy about circumcision was handled (Acts 15; Galatians 2:11-14) appears to repeal a lot of the old laws. But the way I see it, if a law follows from loving one's neighbor or is otherwise reiterated in the Greek Scriptures, it's still something God wants us to do. For example, the commandment to put a railing around the roof of your house so that people don't fall off (Deuteronomy 22:8) follows from "you must not murder", which follows from "love your neighbor as yourself." The commandment not to have gay sex (Leviticus 18:22) is reiterated by Paul (Romans 1:27). The laws about specific composition of clothing (no mixed fabrics, blue thread, tassels) are not; those were intended to establish a distinct Jewish culture. But what the leadership of Pharisaic Judaism did to the Son of God shows that Jews are no longer God's chosen people. As for bacon cheeseburgers, start with Peter's vision of a sheet with animals (Acts 10). This and the resolution of the circumcision problem show that the dietary laws are no longer needed to protect God's people, except for the part about eating or shooting up blood (Acts 15:29).
What bothers me about the article is that they pretend that the best data we had was 14000 years. In the 90's this lake was used to calculate back as far as 45000 years. See this article in Science from 1998.
Science 20 February 1998:
Vol. 279 no. 5354 pp. 1187-1190
DOI: 10.1126/science.279.5354.1187
http://www.sciencemag.org/content/279/5354/1187.abstract
I'll take that as a "confirmed", thanks.
If you were blocking sigs, you wouldn't have to read this.
And another "confirmed". Interesting that the comment itself was down rated.
If you were blocking sigs, you wouldn't have to read this.