Radiocarbon Assumptions Questioned
Every dating method involves assumptions, because historical sciences are not repeatable like laboratory experiments.
Tree ring dating was simple, until somebody realized that more than one ring can be produced in a year. That’s the problem with investigating historical dates; inferences can depend on assumptions that can be overturned. Here are two examples.
Fine-tuning radiocarbon dating could ‘rewrite’ ancient events (Cornell Chronicle). The venerable method of radiocarbon dating is undergoing a rethink. Some archaeologists have used it to settle disputes about historical events, but maybe their confidence was premature.
Radiocarbon dating, invented in the late 1940s and improved ever since to provide more precise measurements, is the standard method for determining the dates of artifacts in archaeology and other disciplines.
“If it’s organic and old – up to 50,000 years – you date it by radiocarbon,” said Sturt Manning, the Goldwin Smith Professor of Classical Archaeology in the College of Arts and Sciences.
Cornell scientists looked into some disputes, such as the date of Tutankhamen and the eruption of Santorini, and realized that some underlying assumptions of the method are not as solid as once thought. For instance, C14 production depends on cosmic rays that hit Earth’s atmosphere. Can scientists be sure that production rate has been constant? Is it the same on both north and south hemisphere?
Cosmic radiation, however, is not constant at all times.
Radiocarbon dating depends on a standard calibration curve that takes into account known deviations, such as those from the nuclear testing era. But radiocarbon intake by plants varies a little by season, also. It records when the tree was undergoing photosynthesis. Comparing tree ring chronologies for different parts of Europe, the scientists found small but not insignificant deviations.
“In northern Europe or in North America, a tree is going to be doing this in April through September. But a tree in Jordan or Israel does that October through April – almost the opposite time of the year,” he said.
These variations, although small, potentially affect calendar dates for prehistory by up to a few decades, the paper concludes.
The team is confident that the deviations are slight, but when trying to nail down historical events, even decades can matter.
The study also has ramifications for understanding which culture influenced the Minoans and Mycenaeans, which led to ancient Greece.
“Getting the date right will rewrite and get our history correct in terms of what groups were significant in shaping what then became classical civilization,” Manning said. “An accurate timeline is key to our history.”
If the assumptions were wrong for known history that can be cross-checked against artifacts and written records, what about potential errors in pre-historical dating? The error bars are not going to get any shorter. Yesterday (20 March 2020) we reported a bird that had been buried in permafrost that was radiocarbon-dated at 40,000 years old, but it looked much fresher than that. An un-witnessed surge in cosmic rays, or a process that could change the ratio of carbon-12 and carbon-14 in the atmosphere, could alter conclusions significantly.
Japan’s asteroid-smashing probe reveals a surprisingly young space rock (Space.com). Students of astronomy have long been taught that asteroids and comets are the most pristine objects in the solar system. Japanese scientists have just called that assumption into serious question. When their Hayabusa-2 spacecraft encountered asteroid Ryugu in 2018, controllers sent an impact device to smash into its surface. They were surprised at the large, 47.5-foot crater the Small Carry-on Impactor (SCI) excavated. Thinking about these results, they concluded that the asteroid cannot be 4.5 billion years old – the assumed age of the solar system. The crater was 7 times larger than what lead author Masahiko Arakawa expected it to be. A drastic revision in age was called for:
Features of the artificial crater and the plume suggested that the growth of a crater was limited mostly by the asteroid’s gravity and not by the strength of the space rock’s surface. This, in turn, suggested that Ryugu has a relatively weak surface, one only about as strong as loose sand, which is consistent with recent findings that Ryugu is made of porous, fragile material.
These new findings suggest that Ryugu’s surface is about 8.9 million years old, while other models suggested that the asteroid’s surface might be up to about 158 million years old. All in all, while Ryugu is made of materials up to 4.6 billion years old, the asteroid might have coalesced from the remains of other broken-apart asteroids only about 10 million years ago, Arakawa said.
Notice the theory-rescue device applied to the observations. The asteroid is young, but it must have coalesced from old material. So what is it? Young? Old? or Yold? The theory-rescue model creates new problems. What happened so recently, and why, to give the young age? If 4.6 billion years were represented by a 46-foot rope, 10 million years would only be 1.2 inches at the young end. It sounds like special pleading when rescue devices are implemented to keep the solar system billions of years old.
In our years of reporting, just about every dating method has anomalies like this. Scientists rely on methods without checking their assumptions carefully. They announce confident dates for things, sometimes with 5 or 6 significant figures. Then, later, somebody finds that one or more assumptions are dubious. There’s a sudden rush to tweak the method a little, as long as they can maintain the moyboy timeline. A few tweaks are made, and the moyboy timeline survives.
Often, the tweaks introduce new problems. For instance, with Saturn’s rings, which have been given an upper limit of 100 million Darwin years, or even less (10 million), some have proposed the unlikely event that an unknown object moving at a finely-tuned speed came close to Saturn and split apart to form the rings. Is that credible? And that’s not the only young-looking thing at Saturn (5 Oct 2019).
That has just happened here. The Japanese concluded that Ryugu is young, but it must consist of billions-of-years-old fragments that coalesced just 10 million years ago. That’s a highly unlikely event. It was suggested in order to save the billions of years. If they concluded the asteroid is only 10 million years old, then it would provide more evidence that the solar system is no older. Since that would overturn Darwinian evolution and the geological timeline, the philosophical cost is too high to even consider seriously. Darwin’s billions of years must be saved at all cost, even if hypothetical improbable events must be imagined out of the vacuum of space.
The solar system is filled with objects that look young – much younger than 4.5 billion years. We have reported on these for 20 years. Almost every object ever visited by spacecraft has astonished planetary scientists by how young it looks. Pluto and Arrakoth are recent examples; Titan and Enceladus continue to baffle the moyboy ‘billionaires’ with their beloved billions of years. Every object from Mercury to the Kuiper Belt gives evidence of youth. And on Earth, there are numerous dating methods that yield young ages. These are routinely tossed in favor of methods that appear to preserve the standard billions-of-years timeline. It is too great an edifice to be easily dismantled. But it stands on a foundation of quicksand.
Remain skeptical of dating methods because of hidden assumptions. Nobody observed billions of years. People have observed only thousands. There’s nothing better than Eyewitness testimony.