Understanding through Discussion

QuickSearch

 Welcome! You are not logged in. [ Login ] EvC Forum active members: 62 (9024 total)
 59 online now: PaulK, xongsmith (2 members, 57 visitors) Newest Member: Moe's URL Addresss Post Volume: Total: 882,823 Year: 469/14,102 Month: 469/294 Week: 225/136 Day: 1/32 Hour: 0/1

EvC Forum Science Forums Dates and Dating

14C Calibration and Correlations

Author Topic:   14C Calibration and Correlations
kbertsche
Member (Idle past 881 days)
Posts: 1427
From: San Jose, CA, USA
Joined: 05-10-2007

 (1)
 Message 27 of 59 (580973) 09-12-2010 6:11 PM Reply to: Message 19 by faith2409-11-2010 7:20 PM

 What does the constant decay rate has to do with the age of the earth? What if the decay rate change, then what happen?

First, I agree with those who say that the decay rate has not changed; we have good experimental and theoretical evidence for this.

Second, even if it had changed in the past (e.g. a hypothesized "accelerated nuclear decay"), this would not affect calibrated radiocarbon dates.

Why is this? Let's consider how radiocarbon calibration is done. We start with tree species which have pronounced annual rings (e.g. N. American Bristlecone Pine, Irish Oak). We both count the rings (to get a calendar date), and radiocarbon date them assuming a constant radiocarbon ratio in the atmosphere and today's decay rate (to get an "uncalibrated" date). This gives us a calibration curve, allowing us to convert uncalibrated dates to calendar dates.

Now suppose you find a piece of old wood and have it dated. How is this done? First, a date is calculated assuming a constant radiocarbon ratio in the atmosphere and today's decay rate (exactly the same way that the calibration curves were done). Then, we use the calibration curves to get the actual calendar date.

How would a change in decay rate (perhaps due to a hypothesized "accelerated nuclear decay" about 5000 years ago) have affected the situation? It would have changed the uncalibrated dates, both for our unknown sample and for the calibration curve. Thus the calibration curve would be different. But after calibration, the date for the unknown sample would come out the same. In essence, the calibration procedure cancels out any changes in decay rate or in atmospheric radiocarbon concentration. A calibrated date depends only on two assumptions:
1) the atmospheric concentrations of radiocarbon were the same at the unknown wood and at the trees which were used for calibration
2) tree rings are annual and we can count them accurately.

 This message is a reply to: Message 19 by faith24, posted 09-11-2010 7:20 PM faith24 has not yet responded

 Date format: mm-dd-yyyy Timezone: ET (US)
 Newer Topic | Older Topic Jump to:Board Administration     The Public Record     Announcements     Proposed New Topics     Suggestions and Questions Science Forums     The Bible: Accuracy and Inerrancy     Big Bang and Cosmology     Dates and Dating     Education and Creation/Evolution     Biological Evolution     Geology and the Great Flood     Human Origins and Evolution     Intelligent Design     Is It Science?     Creation/Evolution Miscellany     Origin of Life Social and Religious Issues     Bible Study     Comparative Religions     Social Issues and Creation/Evolution     Faith and Belief     Theological Creationism and ID Side Orders     Coffee House     The Great Debate     Free For All     Post of the Month     Links and Information     Creation/Evolution In The News     The Book Nook     Columnist     Practice Makes Perfect Archives     Topic Proposals Archive     Showcase Retired Forums     Short Subjects (No new topics or messages)     Welcome visitors