The Book Switch Theory

[proto57]

So they sampled folios f8, f26, f47, and f68.  I understand that "before present" is actually before 1950-01-01.  So, according to that slide, the date for f68 would 1400±35, and that for f8 is 1460±37. That would indeed be a puzzling discrepancy.

But that slide is misleading.  I have now seen the actual calibration dates.  It turns out that, because of a geophysical hiccup around 1400, the measurement of each sample yielded two separate estimates, each with its own range and probability:

f8    1334± 7  3%   1426±32 92%

f26   1335±14 12%   1419±28 83%

f47   1334±10  7%   1420±28 88%

f68   1335±27 42%   1410±25 52%

Hi Jorge: Interesting. Although the basic premise does not change with these new figures, I'm curious: where did you find them? Where did those percentages come from? The 2012 slide I've shown was prepared by Hodgins (sp?)... I'll post it again, for convenient comparison to yours:

   
... and here are the calculations for the appropriate dates which I made, based on those figures:

Folio 8: 490±37, which works out to 1423 to 1497
Folio 26: 514±35, which works out to 1401 to 1471
Folio 47: 506±35, which works out to 1409 to 1479
Folio 68 (cleaned): 550±35, which works out to 1365 to 1435

In any case, again, the point still stands, on examination of these "closer to raw" statistics: They leave open the possibility that, rather than a consistently aged batch of calfskin being used, the maker of the Voynich may have sourced more randomly aged materials they found. And that is important do my mind... because you or I or people with ideas we can't even imagine at this point may find this distinction important and useful. For instance, your speculations below suddently become possible, when we know the reality of the raw results, a knowledge many researchers are denied:

So a better way of reading those results seems to be:

If we assume that all four folios came from the same batch, the date for that batch is about 1420±25 with 90% probability (sorry, rough math here -- too tired now do the proper computation).  

But If we assume that the folios may have come from different batches, like scavenged from old books or from various "reject" bins, there is ~50% probability that folio f68 was made in 1335±30, while the other three were made around 1420; and ~50% probability that all four folios were made around 1420.  In both cases, the dates around 1420 could possibly be 10 years apart or more.

I don't see any objective way to choose between those two priors.   I still think that there is a good chance that the Author used vellum that was already decades old at the time...

Bravo.

The anomalous date and range for f68 on that slide resulted from the "simplification" of combining the two ranges into a single range.  (Imagine that you had the photos of four animals and are asked to estimate their weights.  On three of the pictures the animal is clearly a dog so you say "5±2 kg". The fourth picture is blurry so it could be either a dog or a horse.  Rather than say "5±2 kg with 50% chance,  500±200 with 50% chance",  you "simplify" the answer by saying "300±250 kg"...)

Good example. The one I have often used goes something like this: "If we had a German deed, a French Missel, A British Poem and a Spanish letter, and the radiocarbon dating came out the same as that for the Voynich, noone would even remotely conceive of 'combining' them, and saying all these items came from 1404 to 1438".

by the most rare and fortuitous chance... I had my camera turned on and ready during Greg's lecture at the Voynich 100 Conference in Frascati, Italy, in 2012, and quickly snapped this picture

Indeed I was there and I remember that talk. (I think that the C14 date and Rafal Prinke's biographical info about Barschius were the two notable results presented at that conference.  Were there any others?)  But I did not take a picture, and did not remember that there were four samples, alas...

Well it took a long time, but now you've seen them, too! Maybe there were others in Greg's presentation, but I don't think I caught them. I can look through my original SD card again, and see. And I'll bet you have images from that day that would interest me, and all of us...

All the best,
Rich