Category Archives: Science

Can we trust radiocarbon dating?

Willard Frank Libby, inventor of the method

Can we trust radiocarbon dating? Young Earth creationists tell us that we can’t. After all, it makes the same range of assumptions as other radiometric dating methods, and then some. Other methods benefit from internal checks or duplications, which in the case of radiocarbon dating are generally absent. There are numerous cases where it appears to give absurdly old ages for young material, while apparent ages of a few tens of thousands of years are regularly reported for material known on other evidence to be millions of years old. So can the Young Earth creationist1 objections be rebutted, and if so how?

The principle of radiometric dating is simple.2 If we know how much of a particular radioactive substance was present when a material formed, how much is still there, and Read the rest of this entry

Grand Canyon Unconformities –and a Cambrian Island

I have discussed the Grand Canyon myself at , and strongly recommend this beautifully written and illustrated guide to its unconformities


A prominent ledge punctuates the landscape towards the bottom of the Grand Canyon. It’s the Tapeats Sandstone, deposited during the Cambrian Period about 520 million years ago, when the ocean was beginning to encroach on the North American continent, an event called the Cambrian Transgression. Above the ledge, you can see more than 3000 feet of near-horizontal sedimentary rocks, eroded into cliffs and slopes depending on their ability to withstand weathering and erosion. These rocks, deposited during the rest of the Paleozoic Era, are often used to demonstrate the vastness of geologic time–some 300 million years of it.

View of the Grand Canyon from the South Rim trail. Arrows point to the Cambrian Tapeats Sandstone. View of the Grand Canyon from the South Rim trail. Arrows point to the Tapeats Sandstone.

But the razor-thin surface between the Tapeats and the underlying Proterozoic-age rock reflects the passage of far more geologic time  –about 600 million years where the Tapeats sits on top the sedimentary rocks of the Grand…

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Why historical science is the best kind of science

This is for a planned wide-audience writing project on evolution, in which I pre-empt (rather than respond to) creationists’ counter-arguments, such as their downplaying of historical science. I would greatly value comments on this approach.

There are sciences, such as physics and chemistry, where we can perform experiments. There are other sciences, such as the science of planetary motion (and astronomy in general) where we cannot do this, but we can still carry out repeated observations in well-controlled circumstances, and devise theories with whose help we can make definite predictions. All of these are what I will call rule-seeking sciences. At the other extreme, we have sciences such as palaeontology and much of geology, which one might call historical sciences.1 With these, the aim is not so much to establish general rules, as to unravel and explain the specifics of what happened in the past. It is usual to regard the rule-seeking sciences as the most rigorous, to which the others should defer. This shows a deep misunderstanding of how science works, and, time and time again, when historical and rule-seeking sciences have come into conflict, it is historical science that has triumphed.

Rocks exposed at Grand Canyon, from Proterozoic to Permian. Click to enlarge

A few examples. The rocks clearly show (for detailed arguments, see e.g. here) that the Earth, and by implication the Sun, Read the rest of this entry

NASA launches satellite ‘TESS’ in hunt for exoplanets LAUNCH ACCOMPLISHED

Reblogged from Coel’s blog, where I commented: My own best bet for intelligent life elsewhere would be aroud a red dwarf. More of them, and far longer lifetimes. Our own Sun was nearly half way through its useful lifetime before earth had multicellular organisms. More also, at PhysOrg’s Are we alone? NASA’s new planet hunder aims to find out.

Update, launch delayed

Launch successful


With the launch of NASA’s TESS satellite due this very day, this is a popular-level account of TESS and exoplanet hunting that I wrote for The Conversation. Actually this is my version, prior to their editing.

at the stars in the night sky and wondered whether they are also orbited by planets; our generation is the first to find out the answer. We now know that nearly all stars have planets around them, and as our technology improves we keep finding more. NASA’s newest satellite, TESS (the Transiting Exoplanet Survey Satellite), scheduled for launch on Monday, will extend the hunt for small, rocky planets around nearby, bright stars.

NASA’s TESS planet hunter (artist’s impression)

We want to know how big such planets are, what orbits they are in, and how they formed and evolved. Do they have atmospheres, are they clear or cloudy, and what are they made…

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When dinosaurs roamed the Western Isles

Quite a challenge, I expect, to the local Free Presbyterians.

My friend Kim Johnson commented on the strange appearance of the footprints, Steve Drury (author of the blog of which this is just an annotated repost) referred me to Paige Depolo, senior author of the paper on which Steve’s post is based, and Paige replied as follows:

When it comes to the depositional environment, the tracks were formed in a low-energy lagoon and are generally preserved today as impressions into shaley limestone. Later, additional limestone layers were laid down at the site and in-filled the impressions. Those layers form the casts that we can still observe for some of the tracks today. In some cases at this site, the cast remains while the surrounding impression which it was originally infilling has been almost completely eroded. These rocks were deposited during the Middle Jurassic. Later, likely during the Paleogene, a sill was intruded immediately below the track bearing layer and the surrounding rocks were baked. The low-level contact metamorphism of the track-bearing layers definitely makes for some interesting looking exposures!

h/t Kim and Steve, and many thanks to Paige

Cuillin Hills, Isle of Skye, Scotland, UK Cuillin Hills, Isle of Skye, Scotland, UK (credit: Wikipedia)

The Isle of Skye off the northwest coast of Scotland  is known largely as a prime tourist destination, such as Dunvegan Castle with a real clan chief (The MacLeod of MacLeod) and its Faerie Flag; Britain’s only truly challenging mountains of the Black Cuillin; and, of course, the romantic connection with the Young Pretender, Charles Edward Stuart and his escape, in drag, from the clutches of the Duke ‘Butcher’ Cumberland, hence the Skye Boat Song. Geologists know it best for its flood basalts with classic stepped topography and the exhumed guts of a massive central volcano (the Cuillin), relics of the Palaeocene-Eocene (62 to 54 Ma) North Atlantic Large Igneous Province. The spectacular Loch Coruisk, a glacial corrie drowned by the sea, exposes the deepest part of the main magma chamber. It is also the lair of Scotland’s lesser…

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Truth imitates satire (again) at the Environmental Protection Agency

Trump shakes hands with EPA Administrator Pruitt after announcing intention to withdraw from the Paris Agreement on greenhouse gas emission

“Human activity impacts our changing climate in some manner.The ability to measure with precision the degree and extent of that impact, and what to do about it, are subject to continuing debate and dialogue… [C]lear gaps remain including our understanding of the role of human activity and what we can do about it.”

These are among the talking points distributed to EPA staffers this week.

Have you seen this kind of language before? Yes, you have indeed, from Pruitt himself almost actually a year ago.  At that time, I pointed out that Pruitt was following the script of BBC’s satire, Yes Minister. I have now tracked down the relevant episode, where UK Cabinet Minister (later Prime Minister) Jim Hacker, asks his trusted Civil Servant, Sir Humphrey Appleby, how to deal with evidence that one would rather ignore. Sir Humphrey’s advice:

Discredit the evidence that you are not publishing. This is, of course, much easier than discrediting evidence that you do publish… You say: (a) that it leaves important questions unanswered (b) that much of the evidence is inconclusive (c) that the figures are open to other interpretations (d) that certain findings are contradictory (e) that some of the main conclusions have been questioned. Points (a) to (d) are bound to be true. In fact, all of these criticisms can be made of a report without even reading it. There are, for instance, always some questions unanswered — such as the ones they haven’t asked. As regards (e), if some of the main conclusions have not been questioned, question them!

That, by the way, was about the safety of a chemical processing by-product.

Jim proving he has elbows

Hacker (L) explaining his dilemma to Sir Humphrey

You might perhaps be concerned about the degree of contact with reality with which the EPA (to quote further talking points distributed this week) “promotes science that helps inform states, municipalities and tribes on how to plan for and respond to extreme events and environmental emergencies, recognizes the challenges that communities face in adapting to a changing climate, [and] will continue to advance its climate adaptation efforts.”

But really there’s no cause to worry, because, according to Reuters, Pruitt has “reaffirmed plans for the EPA to host a public debate on climate science sometime this year that would pit climate change doubters against other climate scientists.” It’s not clear where he’ll find his climate change doubters, but I’m sure he’ll manage, and no doubt the debate will take place with the same level of intellectual content and integrity that we have seen from the Senate Environment Committee, or would expect to see in a debate on evolution organised by Vice President Pence.

So stop making a silly fuss about the Government telling scientists to misrepresent the science.

Image and quotations from EPA talking points via Washington Post, 28 March 2018. Quotation from Yes Minster via Hacker/Appleby image via Temperature image from NASA Goddard via Wikipedia; public domain

Why science needs philosophy (cont.), and why it matters, with examples from geology

No one, so far as I know, has any religious objection to the Periodic Table and the unifying concepts of chemistry. But some people do have religious objections to the geological record, and to the unifying concepts of geology, because these  don’t agree with what the most learned men of their time and place wrote down some two and a half thousand years ago.1 And as I argued in my last post, such people will seize on real or imagined anomalies as evidence that the entire intellectual structure is unsound. By contrast, the scientist’s response to such anomalies is to regard them as a potential source of new knowledge, far more likely to extend the framework in a mature discipline than to destroy it.

Example 1: Superposition and overthrusts


Geologcal columnIt is more than 350 years since Steno (who eventually became a bishop) proposed that strata consisted of layers of rock laid down one on top of another, newest on top. We have known for over two hundred years that both the London and Paris basins are filled with relatively recent sediment, on top of marine deposits (chalk or limestone) that emerge in hills to the North and South, that these in turn rest on an older basement, and that the more recent sediments were laid down in layers. The familiar geological sequence, Precambrian upwards (click to enlarge), was established in something like its present form before 1860, by merging the overlapping but incomplete local rock columns, although it was not until the 20th Century that it was recognised that the Precambrian occupied far more of the Earth’s history than everything since that time.

One major disruption of the usual order occurs in the northwest of Scotland, where older rocks lie above younger along a 200 km front. The resulting confusion (the “Highlands Controversy“, fuller account here) was not resolved until the 1880s, with the recognition of what is now known as the Moine Thrust. Read the rest of this entry

Can Curiosity Kill The Sciences?

I am in the middle of a series of posts about scientific method, so this seemed very much to the point. especially, how to avoid acting like a Doctor Authority Figure Type (DAFT), while still defending the value of expert evidence over anecdote (and, I would add, over ideology)?

The Grumpy Geophysicist

There’s a book out there that seems to be attracting lots of lightning bolts (Steven Pinker’s Enlightenment Now!).  GG is not interested in reading or discussing that, per se. It sounds as though logic and empirical observation got confused in there (they are not the same). What got his attention was one of the responses by Ross Douthat of the New York Times, who essentially argues that smugness by those who purport to know better will stifle real science. The nub of the argument is in this quote:

I’m reasonably confident that both of the stranger worlds of my childhood, the prayer services and macrobiotic diet camps, fit his definition of the anti-empirical dark. And therein lies the oddity: If you actually experienced these worlds, and contrasted them with the normal world of high-minded liberal secularism, it was the charismatic-religious and “health food” regions where people were the…

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In praise of fallibility; why science needs philosophy, with examples from astronomy and chemistry

[Adapted from 3 Quarks Daily] More recent strata lie on top of older strata, except when they lie beneath them. Radiometric dates obtained by different methods always agree, except when they differ.  And the planets in their courses obey Newton’s laws of gravity and motion, except when they depart from them.

As Isaac Asimov reportedly said, “The most exciting phrase to hear in science, the one that heralds new discoveries, is not ‘Eureka!’ [I have found it], but ‘That’s funny …’ ” And there is nothing that distinguishes so clearly between the scientific and the dogmatic mindset as the response to anomalies. For the dogmatist, the anomaly is a “gotcha”, proof that the theory under consideration is, quite simply, wrong. For the scientist, it is an opportunity. If an idea is generally useful, but occasionally breaks down, something unusual is going on and it’s worth finding out what. The dogmatist wants to see questions closed, where the scientist wants to keep them open. This is perhaps why the creationist denial of science can often be found among those professions that seek decision and closure, such as law and theology.

The rights and wrongs of falsification

Karl Popper

Karl Popper (LSE Library photo, 1980s)

Dogmatists regularly invoke the name of Karl Popper, and the work he did in the 1930s. Popper placed heavy emphasis on falsifiability, denouncing as unscientific any doctrine that could not be falsified. Freud’s theories, for example, Read the rest of this entry

Evolution, the Iraqi Translation Project, and science in the Arab World

Translations change the course of civilisations. The translation project begun by Caliph al-Mansour in the 8th century CE, and accelerated under his grandson Harun al-Rashid, made available in Arabic scholarly writings from Greek, Aramaic (Syriac), Persian, and Indian sources, and laid the foundation for the flowering of science and philosophy in the Islamic world during Europe’s Dark Ages. A second translation project, from the 10th century onwards, was in the other direction, from Arabic to Latin. Among its initiators was Gerbert d’Aurillac, the future Pope Sylvester II, and it reached its height in Toledo in Spain where for a while Christianity and Islam came into close contact and where Gerard of Cremona translated al Khwarismi and Avicenna (ibn Sina), as well as Arabic versions of works by Ptolemy and Aristotle. It refreshed Europe’s contact with classical learning, while also conveying what was then current scholarship. It was the pathway through which Christian Europe rediscovered Aristotle, while Avicenna’s clinical expertise is mentioned in the Canterbury Tales. His writings on geology, which I have discussed elsewhere, were among those translated at this time, but originally misattributed to Aristotle.

Avicenna_Expounding_Pharmacy_to_his_Pupils_Wellcome_L0008688L: Avicenna expounding pharmacy to his pupils, from the 15th century “Great Cannon [sic] of Avicenna”; Wellcome Library via Wikimedia. Click to enlarge.

Happily, if belatedly, another translation project is now under way, from English to Arabic, focused largely on science-related topics of general interest, with special attention to evolution.

Why evolution? Not only because of its central role in modern life sciences, but because Read the rest of this entry

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