Archive for December, 2017

Chromium Opprobrium

December 18, 2017

Perhaps the most serious error that contemporary society makes about science is that all its results are equally credible. One of the main themes of Genesis and Genes is that science operates on different levels; results in some realms of science are credible, while results in other areas should be treated with considerable scepticism. In particular, one should be wary of claims about events that allegedly occurred millions or billions of years ago and are not amenable to direct observation.

This is a point that is misunderstood not only by the vast majority of laymen, but also by professional scientists. Here is an excerpt from Genesis and Genes.

[Beginning of excerpt]

With this in mind, let us consider this statement by a contemporary scientist and author:

Radioactive carbon-14 had a 5600-year half-life in the early universe just as it has now.[1]

This is the voice of faith. The truth is that we do not know and cannot know the half-life of carbon-14 in the early universe. We were not there, and any conclusions made on the basis of current measurements, no matter how plausible, will be based on assumptions about how nature’s laws operated in the past. Often, these assumptions are left unstated, so that the public is convinced that measurement of the cosmic background radiation, for example, is a direct measurement of some parameter that characterised the early universe. It isn’t. The theory from which the measurements derive their importance assumes, at the very least, that certain laws of nature operated at specific rates throughout the past, all the way back to the beginning. We shall never know whether this assumption is justified. Nonetheless, many contemporary scientists are committed to the principle of the immutability of natural laws. Whatever laws are operative today, they maintain, have always operated, and always at the same rate.

[End of excerpt]

One of the most important parameters in Origin-of-Life research is the atmospheric concentration of oxygen. All models that deal with the emergence of life on Earth rely on conclusions about how much oxygen our atmosphere contained at various points of Earth’s history. One reason for this, of course, is that large mammals like human beings need a high concentration of atmospheric oxygen to “operate”. A second reason is that too much oxygen in the atmosphere would lead to spontaneous fires erupting everywhere, not a scenario guaranteed to provide comfort to any emerging life. But perhaps the most important point is that oxygen, being a reactive (that is, destructive) molecule, makes it immensely unlikely that delicate organic reactions could have happened in the remote past. Abundant atmospheric oxygen would simply have wrecked these fragile processes before they had a chance to even begin.

So, how do you measure the atmospheric concentration of oxygen in Earth’s atmosphere billions of years ago? Not surprisingly, the answer is, “With great difficulty.” One of the standard techniques involves measuring the ratio of two isotopes of the metal Chromium in ancient rocks. [Isotopes are versions of the same element; every atom of the element has the same number of protons in its nucleus, but different isotopes contain different numbers of neutrons.]

New research sheds interesting light on the possible pitfalls in this kind of research.[2] A report about research done at the Georgia Institute of Technology begins with the following paragraph:

For researchers pursuing the primordial history of oxygen in Earth’s atmosphere, a new study might sour some “Eureka!” moments. A contemporary tool used to trace oxygen by examining ancient rock strata can produce false positives, according to the study, and the wayward results can mask as exhilarating discoveries.

What is going on? The article continues:

Common molecules called ligands can bias the results of a popular chemical tracer called the chromium (Cr) isotope system, which is used to test sedimentary rock layers for clues about atmospheric oxygen levels during the epoch when the rock formed. Researchers at the Georgia Institute of Technology have demonstrated in the lab that many ligands could have created a signal very similar to that of molecular oxygen.

In other words, you think you’re measuring A, but in reality B is interfering and giving you results that mislead you. The result is

“There are some geographical locations and ancient situations where measurable signals could have been generated that had nothing to do with how much oxygen was around,” said Chris Reinhard, one of the study’s lead authors.

This is not just theory. The article states,

But some researchers confronted with odd Cr signals have thought they had perhaps stumbled upon a radical find, and they developed explanations for how O2 [oxygen] may have been surprisingly bountiful on the lonesome spot where a particular rock layer formed, while molecular oxygen was scant on the rest of the globe. Others puzzled that atmospheric O2 levels may have risen much earlier than overwhelmingly broad evidence has indicated.

“A lot of that could be chalked up to other chemical processes and not to interactions with oxygen,” Reinhard said.

&&&

There are at least two important conclusions to draw from this research. Firstly, when you read popular accounts of scientific research, words like measure pop up frequently, and provide a misleading impression of the process used to obtain the results. Very often, research does not directly measure whatever quantity the scientists are after. Rather, there is a proxy that is believed to serve as a reliable marker for the desired quantity. What the public fails to appreciate, however, is that the line between the proxy and the desired quantity is not straight; it is not even a line. It is a convoluted and intricate curve, and it is vulnerable to many obstacles.

Dr. Gerald Schroeder often confuses the proxy and the desired quantity in Genesis and the Big Bang. Here are typical statements from his book:

Cosmologists measured the age of the universe…; The age of the universe has been measured using a variety of independent… systems; …Phenomena that are readily measurable by modern archaeological, paleontological and cosmological instrumentation;

These remarks are phenomenally misleading. The supposed measurement that is spoken of here consists of numerous intricate steps, each of which depends on its own assumptions and is subject to unstated pitfalls.

This is precisely what you see in the Georgia Tech study. Popular accounts of this type of research omit the necessary caveats, and describe scientists as measuring the concentration of atmospheric oxygen. They do no such thing. There is a complicated process which is believed to reflect the desired quantity. If one understands this, and is aware of how often proxies turn out to be unreliable indicators of various quantities, the credibility of such reports is considerably diminished.

The second major lesson to take home is that – surprise! – science is not infallible. Until the research at Georgia Tech, nobody was aware that ligands could mimic the effects of various isotopes of chromium and thereby throw off the researchers. As the article makes clear, “some researchers confronted with odd Cr [chromium] signals have thought they had perhaps stumbled upon a radical find, and they developed explanations for how O2 may have been surprisingly bountiful on the lonesome spot where a particular rock layer formed…”

All sorts of theories and conclusions flowed from various findings which, in hindsight, turn out to be mistaken. Informed consumers of science would do well to adopt a more sceptical stance towards origin-of-life research.

SOURCES:

[1] Genesis and the Big Bang, Gerald L. Schroeder, Bantam Books, paperback edition 1992, page 29.

[2] http://www.rh.gatech.edu/news/598840/popular-tool-trace-earths-oxygen-history-can-give-false-positives. Last retrieved 18th December 2017.

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