Shroud of Turin – Carbon Dating Witness

This post is part of a multi-part series investigating the evidence and arguments surrounding the Shroud of Turin. See the first post, Shoud of Turin, Could it Be Real?,  for an index.

This witness is complex, filled with as much passion and fervor as scientific analysis and investigation. 1988 was a pivotal year in the study of the Shroud, when the carbon dating findings were released from three laboratories that analyzed Shroud fibers and determined it was not 1st century material. In science, once new data is published, even if it is wrong, it takes mounds of additional contrary evidence to suppress the inaccurate data. In this case, three laboratories analyzed the fabric and came to the same conclusion on the date. Rather than throwing in the towel after all of our previous study, lets understand the activities and processes that led the labs to reach their conclusions.

Their conclusions state:

“Very small samples from the Shroud of Turin have been dated by accelerator mass spectrometry in laboratories at Arizona, Oxford and Zurich.  As Controls, three samples whose ages had been determined independently were also dated.  The results provide conclusive evidence that the linen of the Shroud of Turin is medieval”

When reputable scientific sources have reported that the carbon dating of the Shroud is late 13th to early 14th century, how does one disregard that and continue to make the claim that the Shroud is a 1st century connection to Christ?

The three laboratories’ radiocarbon measurements were made by analyzing four textile samples each, a total of twelve data sets. From the data presented, none of the measurements differed from the mean value of its set by more than two standard deviations. The results for the control samples at each lab corresponded with previous radiocarbon measurements and/or historical dates, indicating the calibrations were all correct. Collectively, this is very strong evidence that the labs accurately measured the samples.

All of the textile samples provided to the labs were taken from a single location on the Shroud, in a heavily handled area. Textiles are notoriously difficult to carbon date due to their tendency to hold and trap contaminants. The test protocol for preparation of textile analysis typically includes a preparatory cleaning for this reason, with many labs using their own technique for the preparation. The sample collection team’s original plan was to take samples from seven different locations. This plan was well thought out and scientific, but was drastically changed at the last minute by the custodian of the Shroud.

Significantly, the last-minute change to the sample collection protocol dictated the location from which the single sample would be taken. Upon further investigation, this region was not only heavily handled, but appears to have actually been a patch added to the Shroud. As Ray Rogers pointed out, he was convinced that the location and material taken caused misleading conclusions. He is fully convinced that the laboratories got the date correct for the samples they analyzed…they just didn’t analyze fibers of the original Shroud material.

In review of the written summary of the scientific handling and preparation of the samples there is another concern beyond the location. As a result of the absence of a chemical analysis before and after cleaning, there is no information concerning the relative effectiveness of the various cleaning treatments. This violates basic principles of sample preparation and analysis – to know the chemical composition of the material being studied.

As I reported earlier, one thing that stood out in the Critical Summary of the Shroud produced by the Shroud Center of Colorado is found in their conclusion:

“First, the conclusion that the Shroud was in Constantinople in 1204 is strongly supported, both historically and empirically. Such a conclusion means the carbon dating of the sample cut from the Shroud failed to date the Shroud correctly.”

After a review of the available record of the events leading up to carbon dating and the analysis itself, several significant concerns arise. The samples were:

  1. …small, then subdivided and exhausted, meaning no further analysis is possible.
  2. …collected from a single location on the Shroud and not multiple locations as originally planned. This location was was heavily handled, and as a result is suspected to have been contaminated.
  3. …not analyzed before and after cleaning, meaning the impact of cleaning was not documented.
  4. …reportedly collected from a location on the Shroud that was patched, meaning the conclusions may in fact only be representative of the patch itself.

Research on the Shroud is incredibly extensive for a single historical artifact. Papers on the subject, both for and against its connection to Jesus Christ, are vast. If this were an object with no religious overtones, there would be little serious doubt as to its veracity. But being the purported burial cloth of Jesus Christ and carrying the possibility of a witness to his resurrection, the Shroud raises powerful emotions and passions.

The blog posts in this series have included many links to resources A useful summarizing paper, in addition to the publications by the Shroud Center of Colorado and Thibault Heimburger, is Richard Sorensen’s “Summary of Challenges to the Authenticity of the Shroud of Turin.”

I hope you will join us this evening for my Shroud of Turin Lecture at Faith Evangelical Lutheran Church near downtown Houston. I look forward to an engaging discussion following the talk and here on the RFH blog!

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