I guess this is a response to the claim I sometimes read that “We choose our beliefs”. I think there’s some truth in that, but would supplement it: “We choose our beliefs… but the universe pushes back”.

What do I mean by that? Perhaps an analogy that I owe to Ernst von Glasersfeld will be helpful. He describes our experience of the universe as like being blind-folded in a pitch black forest and having to find our way out. We can’t see a thing, and some paths are blocked by tree trunks, deadfalls, cliffs, rivers and so on. We can feel a way out by touch, but it’s not the only possible way: there are others, perhaps many others. Some of them will be shorter and better than the one we found, so it’s worthwhile to keep exploring.

He suggests that we don’t have direct access to the universe itself to observe and measure it. Our access is always mediated by our assumptions and by the limitations of our senses. He’s an ‘instrumentalist’, in philosophical terms: our theories are not the truth about reality, they’re just useful for our purposes.

So a concept like the ‘quark’, which we can’t see directly but must infer from experiments, is not seen as ‘real’, but as a concept that is helpful for explaining the behaviour of subatomic particles. But something we can see, like light – the thing we use to see – is also understood as a concept, rather than reality itself.

Some people – who usually have some form of motivated reasoning going on, either in terms of selling something or persuading others to an ideology – tend to take that and say “No-one has direct access to reality, so anyone’s beliefs are as good as anyone else’s, and no-one can be told they’re wrong”. Doesn’t matter whether it’s anti-vax, climate change denial or recent creationism, these philosophical ideas tend to be abused to suggest there is no meaningful difference between different knowledge claims.

This is where the notion that “the universe pushes back” becomes important. Because it does. No matter what your beliefs, if you step off a tall building, you will plummet toward the ground. No belief system will change that. If you don’t get your kids vaccinated, and they’re exposed to the disease, they (very likely – it’s more probabilistic than gravity) will get the disease. If you pump vast quantities of carbon dioxide and methane into the atmosphere while cutting down forests, the global climate will warm.

When finding our way out of that forest, it’s pretty easy to slam into a tree really hard.

We can certainly have an argument about realism vs instrumentalism. I kinda doubt we’ll solve it, since philosophers have been debating it for decades. But either way, really: the universe pushes back.

Never fear, not another weight-loss post (which my Facebook friends have seen from me ad nauseum)! My title is drawn from a line I love:

Do I contradict myself? Very well then, I contradict myself. I am large, I contain multitudes.

Walt Whitman

People on Facebook and Twitter have mentioned occasionally (and, I suspect, thought more than occasionally) that I’m difficult to pin down. It’s not entirely clear what I believe on a whole range of issues.

Sometimes that is ‘read’ as being dishonest or strategic. I don’t think it is: if someone wishes to ask a straight question about what I believe, I’m always willing to give a straight answer. That answer itself might be ‘it’s complicated’… and might then spin out into something like a blog post. That’s because I’m very comfortable with ambiguity and complexity, so what I really think about something is often not easy to communicate in a sentence.

I guess the other thing is that I’m happy to talk to other people in their own register, not in mine. I recently wrote a piece, which will be published in Adventist Today in a month or so, about climate change. I clearly outlined the science, but also made the point that it is the most vulnerable people on Earth who will be most harmed. I quoted the book of Revelation, which says that at the Second Coming Christ will return to ‘destroy those who destroy the Earth’, and I quoted Matthew 25 where Jesus talks about what his followers have done for ‘the least of these’.

For myself, I don’t necessarily believe that there will be a Second Coming. It seems wildly improbable to me. But I’m not being dishonest, I don’t think, in speaking to Christians in the language of their own wisdom literature, to motivate them to act in a way that is simply humane and human. To clarify for them that, despite the ‘prosperity gospel’ and all the deeply evil shit some of their ‘leaders’ espouse, if you actually look at what Jesus (is reported to have) said in the Bible, it’s generally a decent guide to life.

One of my atheist friends immediately commented one of the less lovely things Jesus (is reported to have) said, about creating division between families, and used that to dismiss everything Jesus (is reported to have) said. I see that approach pretty often, but I don’t necessarily see it as a way of having a connected human conversation with people.

I try to apply the same approach to other belief systems, unless and until they’re harmful. Taking the vitamin and herbal supplements your naturopath prescribes is, to me, a silly way of creating very expensive urine (because with a balanced diet, most supplements go straight through us), but I’m happy to leave you to it… until s/he prescribes bicarb soda instead of chemo for your cancer (because s/he believes it’s fungal) and significantly shortens your life.

So yes, I’ll engage with Christians on their own terms – until they’re opposing same-sex marriage in Australia or working toward the death penalty for gay people in Uganda: then I’ll resist them as hard as I can.

I guess there’s the danger of seeming condescending with this approach: “Oh well, I have this ascended understanding, so I can talk to all these deluded people in their own language to try to enlighten them.”

I don’t think it’s that, though. I think it’s an attempt to make a genuinely human connection ‘across the aisle’ with everyone. To hold no person in contempt… but to support and advocate for ideas that lead to human flourishing, and challenge ideas that do harm.

So, if you’re confused by who I am and what I stand for (a) I hope this little chat has been helpful and (b) so am I, a lot of the time and (c) ask!

Returning to the creationism well one more time, and then I really will leave it alone and talk about something else for a while!

Human groups around the world have a wide range of different creation and origin stories for Earth and life. For the purposes of this, I’ll only talk about Christian creation stories. But I do encourage you to read widely and get a sense of the range. There’s an interesting list here: http://www.gly.uga.edu/railsback/CS/CSIndex.html

Basically, the two (slightly different) creation stories in the first and chapters of Genesis, the first book of the Bible, have been interpreted in a range of ways. And each interpreter will loudly and repeatedly tell you that their particular interpretation is the simple, clear, plain and literal reading of the text, and all other interpretations are heretical or worse.

If we consider ‘young’ to mean something like ‘less than 20,000 years old’ and ‘old’ to mean something like ‘more than 10 million years old’ (because almost no-one believes that any of the things we’re about to talk about happened in the space between those periods. No-one things Earth is middle-aged, apparently. It’s a bimodal distribution.

So there is a range of possible views, within that scheme:

1. Universe, Earth and life is young
2. Universe is old, Earth and life is young
3. Universe and Earth are old, life is young
4. Universe, Earth and life is old

The interesting thing is that of these, only 4 does not require any kind of supernatural intervention – but 4 is still completely consistent with the possibility of supernatural intervention. That is to say, only 4 allows sufficient time for natural processes to create everything we see around us.

When I say ‘Earth’ above, it’s probably worth noting that that might mean ‘Earth and our Solar System’. The relevant texts in Genesis 1 talk about the creation of the Sun and Moon:

¹⁴ And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and years:

¹⁵ And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.

¹⁶ And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.

¹⁷ And God set them in the firmament of the heaven to give light upon the earth,

¹⁸ And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.

This occurs after the creation of plants, and some folks like to make a ‘gotcha’ of that, but I don’t have a lot of appetite for that kind of frame-shift argument.

A lot tends to hinge, in arguments between proponents of the various positions in the numbered list (1-4) above, on the few words I’ve bolded above in Verse 16: “he made the stars also”. If their positioning with the creation of the sun and moon means they were created at the same time, the universe must be young, and only position 1 is tenable. Many interpret it as a parenthetical comment that allows the possibility that God made the stars, but some considerable time earlier.

To some extent these are accommodations between science and religion, but they are also readings of an ancient text through modern eyes. Terry Pratchett captured it nicely “the stars began to come out, like pinholes in the curtain of night. Or like enormous exploding balls of gas, as some people would say. But some people will say anything.”

The distinction between Earth, solar system, galaxy and universe is not something that would have been a commonplace for people almost 3000 years ago: they’re not even necessary commonplaces for many people now.

I believe that conflict between science and religion is not inevitable, but that conflict between science and certain simplistic readings of religious texts is much more common. Once a religion has become organised, there is systematic pressure to preserve particular interpretations.

I do always find it interesting to observe the passionate arguments between people who believe very strongly that a particular text is sacred and infallible, but read it very slightly differently.

Every couple of months this year I’ve written a short piece on the relationship between science and religious faith for a site called ‘Adventist Today’. (Searching my name in the search bar in the page will easily bring up all of the pieces published so far.)

The most recent has just appeared, so I thought I’d share it here, since it addresses similar concerns to some of of the recent posts here. I don’t think I’ve repeated myself too much…

Hope you find it interesting and useful. There’s a link at the bottom to the Adventist Today Facebook page where discussion usually ensues. (If your background is not Seventh-day Adventist some of the discussion may require a little interpretation…)

A short and simple explanation

This is the final post in this short series. It is the 12th, and a dozen seems like a reasonable tally. The sequence, as a set, is meant to allow someone who encounters a particular claim or meme to quickly access a clear, accurate response, written for a smart non-specialist. It’s by no means sufficient in terms of evidence, but hopefully it frames up the issues in a way that is helpful when someone goes looking for further evidence.

While I’m talking in this ‘meta’ way, can I encourage everyone, including myself, to always seek ‘disconfirming evidence’ and ‘discrepant cases’? Confirmation bias is real, and oh so tempting: to seek the evidence that confirms us in our existing views, and discount any that challenges them. The only approach that works, though, for anyone who values a life founded in truth, is to be always looking for the evidence that makes us change our minds.

This final topic is related to the earlier one on probability, but the focus is slightly different.

Complexity science is a fascinating and genuine area of study… but also one that is susceptible to being used as a ‘handwave’ in ways that are not scientific. Much like Deepak Chopra and his self-help ilk talk about ‘quantum indeterminacy’ to support their woo, “It appears complex therefore science supports the explanation I support” is not really an argument.

There are a number of different ways to think about complexity, and no definition is particularly universal. There isn’t a real convention. After having spent a fair bit of time reading, the following is just my best understanding, which reflects a number of influential perspectives in the field, but remains controversial.

In brief, the distinction – and it’s a philosophical one – is between things that are complicated and things that are complex. Lots of things are complicated: the internet, as a network of wires and a web of communications protocols, is complicated. Cells are complicated. Economics is complicated. In this definition, though, things that are complicated are able to be reductively analysed by breaking them down into simpler bits. While the complication is insane, it’s possible to understand each of the cables in a server farmer and what it does… and many server farms build a network. It’s possible to look at a data packet and know whether it’s organised with the ftp or http protocol.

Complex systems, on the other hand, exhibit emergent behaviours that are not able to be explained in terms of reduction to simpler components. We could argue that human brains are complex in this sense, for example: self-consciousness is not easy to explain in terms of neurons and neurotransmitters and potentials and neuroplasticity.

The question of whether a particular system is complicated or complex in this sense is not simple to determine in any final sense. It may just be that we haven’t yet thrown sufficient computational resources or smart enough algorithms at our reductive analysis. If resources short of infinity could analyse a system, it can be argued that it is merely complicated, not complex… and the case needs to remain open for a lot of things.

That approach is different from the concept of ‘irreducible complexity’ that tends to be used by the Intelligent Design advocates. They tend to launch from comments such as the ones Darwin himself made in ‘Origin’, about how difficult it is to imagine a process by which the eye could evolve. Darwin does not despair of it, however, and plausible sequences have been outlined. Eyes tend not to fossilise, so hard evidence is challenging to find, but there are numerous kinds of different eyes, and it appears as though eyes may have evolved multiple different times independently.

The key issue in their approach is assuming that an eye is ‘irreducibly complex’ – that unless there is an eye in pretty much its current form, with eyelids, muscles to turn it, a lens, an iris, a retina and optic nerves, rods and cones for black-and-white and colour vision, it is not an eye at all, and conveys no survival advantage. But much simpler eyes exist, right down to simple light-sensitive spots, and convey survival advantages significant enough to lead to selection. The notion of irreducible complexity is built on the misconception that complex systems must spring into existence in pretty much their current form from essentially nothing. But refuting something evolution does not predict does not refute evolution.

They have moved on from the eye, and things like the flagella that bacteria use to propel themselves, to DNA and the processes of cell division and replication – the most fundamental processes of life itself.

They are right to say that these processes are complex in a way Darwin couldn’t have known or imagined 150 years ago, and indeed, we have learned much more in just the past few decades. It’s quite amazing that our DNA has multiple independent self-repair mechanisms: when things go wrong they are often corrected, or the process aborted. Cancer would be far more common if these processes were not in place. They’re nothing we can yet reliably build in to our code, let alone to our material machines.

While fully accepting the complexity of the cell – which is wondrous – the argument that it could not have evolved, because it needs to exist in pretty much its current form to work at all, recapitulates many of the arguments about the eye and the flagellum, and is wrong for the same reasons.

There are plausible, but still quite early, proposals for simpler RNA-only replicating sequences that may have pre-dated, and evolved to form, the current very complex systems.

Life is, indeed, complex. Whether irreducibly so is a philosophical question. But arguments from that complexity for a divine Creator – by fiat ex nihilo or by tinkering at the edges – are not strong arguments.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiocarbon dating
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils

In a way, this is more of a philosophical post than a paleontological one. From slightly different perspectives, either there are many ‘transitional fossils’, or there is no such thing. And both those views are consistent with the fossil record!

I’ve certainly said “There’s no such thing as a transitional fossil” before. What did I mean by that? Well, no species of living thing is ever ‘on the way’ to a different species, ‘in transition’ from one thing to another. Each living thing – and each population of living things, which is the unit evolution works on – is simply living. Simply being as well adapted to its particular ecological niche as it can possibly be, in order to live, move, breed and pass on its genes.

So a fossil of a living thing is, in a very real sense, not ‘between’ two other species. It is simply itself.

At the same time, in retrospect, we can reconstruct the ‘tree of life’ – the sequence from simpler to more complex organisms over time. (It’s worth noting that, more recently, this reconstruction is a dynamic process that includes DNA evidence as well as the fossil record.) That sequence is not linear: it is branching, and has many, many dead ends. The fact that there are more complex organisms doesn’t mean the simpler ones go away: bacteria, viruses and archaea are still with us today.

So, in the sense that we can reconstruct the sequence, in a sense any fossil that is not the fossil of a present-day species can be thought of as a transitional fossil, since that species had both ancestor species and successor species.

What is usually thought of as a transitional fossil, of course, is something that has obvious features of both its ancestors and its successors. Archaeopteryx, for example, is a bird-like dinosaur with teeth and feathers. It seems likely now that it was more of a dead-end than a transitional species, but it is the kind of thing we think of. (It is also believed now that many more dinosaurs had feathers than first thought: they’re just less easily fossilised than bones.)

There are fossils of limbed species that we believe are ancestors of modern whales, and modern whales have vestigial hips that suggested their ancestors had limbs. We could even argue that whales are ‘transitional’ to future ocean-going species in which those vestiges have completely disappeared.

As usual with these little posts of mine, checking out the Wikipedia page on ‘transitional fossils’ will add a lot more detail and a lot of examples, and googling the term will… well, frankly, lead you to a lot of examples but also a lot of ill-informed claims that such things have never been observed.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiocarbon dating
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Complexity – irreducible and otherwise

Recent discoveries in genetics have led to the publication of some interesting work that has suggested that all currently living human beings can be traced back to a single human female on the order of 120,000 to 150,000 years ago. In the 1980s this individual was dubbed ‘Mitochondrial Eve’. Similarly, all modern humans can have their ancestry traced back to a common male ancestor, dubbed ‘Y-chromosomal Adam’, who lived a similar time span, or perhaps 20-30,000 years longer, ago.

While this is not 6,000 years, or even the fewer-than-20,000 often accepted by creationists, misconceptions about these concepts led to considerable excitement in creationist circles. Many assumed that these two individuals were married to each other, and were the single married couple of humans from whom all modern human beings descended.

It mightn’t be 6,000, but it wasn’t millions, and with their related misconceptions about dating, the dates could be set aside. The key was the ability to link it to the Genesis story of a First Couple, and to claim that humans have not evolved, but have always and only descended from humans.

These are misconceptions, though, and the purpose of this post is to very briefly explain why. Obviously it’s a short and simple explanation: there are more detailed ones out there, and the Wikipedia explanations of both are good and detailed.

First, in both cases, saying that all of us can trace our lineage back to an individual does not mean that that individual was the only person alive at that time!

We all have a vast number of ancestors. There’s a conundrum here. I have two parents, 4 grandparents, 8 great-grandparents, 16 great-great-grandparents and so on. It’s a sequence going up in powers of 2: I’m 2⁰, my parents 2¹, grandparents 2², great-grandparents 2³ and so on.

If we assume a human generation is about 20 years, that’s 5 generations a century, 50 a millennium. Perhaps 50 x 150 = 7,500 in 150,000 years. But the thing is, 2⁷⁵⁰⁰ is 5.3 x 10²²⁵⁷. There are only about 7.5 x 10⁹ people on Earth right now, and that’s the most there’ve ever been: certainly not that other outlandish number.

The solution is that some of our ancestors were the same people. Quite a lot of them, as it happens. That is, given slightly older and younger child-bearing and other things, my 6-greats-grandfather on my father’s side might also be my 7-greats-grandfather on my mother’s side… or even take on more roles across generations.

And, of course, we don’t simply multiply the number of my ancestors by the number of people in the world to find out how many ancestors there were in the world, because some of my ancestors are also the ancestors of other people. Most trivially, my parents are also the parents of my siblings. My dad in particular is from large families going back generations, so some of my great-grandparents are ancestors of an enormous number of people, not just of me.

Mitochondrial Eve and Y-chromosomal Adam are simply the two individuals – probably living in Africa, but almost certainly not close together, in either space or time – who in each case are the most recent ancestor shared by all modern living humans when traced back using particular genetic techniques. And they are probably not unique.There may be multiple people fulfilling that criterion, although conceptually only one individual can be the most recent.

It’s also important to note that, in both cases, these are theoretical concepts, not actual individual people with names and addresses who have been identified.

So, to take ‘Eve’ first, mitochondria are the little ‘energy factories’ in our cells. They have different DNA in them than the DNA in the remainder of our cells. (They may well have arisen as bacteria that were symbiotic with other cells and then were incorporated, but that’s a whole separate fascinating story.)

Mitochondrial DNA is matrilineal (passed down via our mothers), and we can look at shared characteristics and their changes over time to calculate a ‘clock’ back in time until we have a common female ancestor. This is what is meant by the time back to the ‘Mitochondrial Eve’ theoretical concept.

Being able to make this calculation is an important and very interesting development in our understanding of genetics, but it does not mean that there was only a single human woman, 120,000 to 150,000 years ago, who was mother to us all.

The story for ‘Adam’ is very similar, but Y chromosomes tend to be passed down patrilinearly, from fathers to sons. The tracking back is essentially by a similar process of genetic reconstruction.

Exciting, very interesting science… but, when properly understood, no particular comfort to those who want all human beings to have descended from a single divinely created couple in Eden.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiocarbon dating
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Transitional fossils
Complexity – irreducible and otherwise

Something a little different today. I thought I’d share a video, rather than a block of text. Depending on your interest level, there’s a sub-2 minute version and a roughly 13 minute version. If you watch the latter, you’ll see that one of the affordances of video over text is the ability to do hand-waves!

This doesn’t really fit within the current sequence on addressing objections to evolution… except that perhaps it kinda does…

If your interest level or tolerance for my waffling is a bit higher…

Thanks to Griffith University for use of the video suite: I’m sure science communication is part of my job, right?

In the face of the claim that all forms of life were recently divinely created in something much like their current form, there is abundant evidence of new species forming right now, all around us.

The definition of the term ‘species’ is a relatively complex, and somewhat contested, matter in biology. A quick rule of thumb is that members of different species can’t reproduce sexually with one another in a sustainable way. It’s probably not a full and accurate definition, but it works for most cases.

That last distinction, about sustainability, addresses situations like mules: the offspring of a horse and a donkey, which are different species, is bred by humans for our purposes but is itself barren and unable to reproduce. If humans stopped breeding mules, they’d die out in a generation (I guess aside from random liaisons between wild horses and donkeys).

We see new species of plants, birds, insects, fish, amphibians and other species with relatively short lifespans arise regularly: I won’t link here, but just google ‘observed speciation’ for plenty of examples.

(If I were a real biologist I’d spend more time on all the layers of kingdoms and genera and phyla and families and such, but I’m not, so I won’t: there are very good Wikipedia guides if you’re interested.)

The common creationist response is the one that was parodied with ‘crocoduck’ memes: “We have never seen a fish turn into a cat: the new species you talk about look exactly like the thing they evolved from”. This is related to the claim that there are no ‘intermediate species’ in the fossil record: what they are looking for is something that is very obviously partly one recognisable modern species and partly another.

When faced with evidence of the ways in which species adapt to their environment – including things like the development of antibiotic-resistant bacteria – the creationist response is often “Well yes, God designed in adaptability to help life survive, but that’s only micro-evolution within species. Macro-evolution that creates new species (that are visibly and noticeably different) doesn’t and can’t happen.”

One of the quasi-scriptural notions used to support this distinction between micro- and macro-evolution is ‘baramin’. It’s not a real Hebrew word, it’s a recently-coined (well, 1941) term that (ungrammatically) combines the Hebrew words ‘bara’ (created) and ‘min’ (kind).

The scriptural creation account includes these phrases:

Genesis 1: 11-12, 20-21, 24-25 (King James version)

¹¹ Then God said, “Let the land produce vegetation: seed-bearing plants and trees on the land that bear fruit with seed in it, according to their various kinds.” And it was so. ¹² The land produced vegetation: plants bearing seed according to their kinds and trees bearing fruit with seed in it according to their kinds. And God saw that it was good.

²⁰ And God said, “Let the water teem with living creatures, and let birds fly above the earth across the vault of the sky.” ²¹ So God created the great creatures of the sea and every living thing with which the water teems and that moves about in it, according to their kinds, and every winged bird according to its kind. And God saw that it was good.

²⁴ And God said, “Let the land produce living creatures according to their kinds: the livestock, the creatures that move along the ground, and the wild animals, each according to its kind.” And it was so. ²⁵ God made the wild animals according to their kinds, the livestock according to their kinds, and all the creatures that move along the ground according to their kinds. And God saw that it was good.

The phrase ‘according to their kinds’ is interpreted to mean something roughly analogous to the notion of ‘visibly different organisms’. It doesn’t really translate neatly to any level of the biological taxonomy.

In biology, there is essentially no mechanism that would prevent successive small changes in a population accumulating to produce larger changes: for many micro-evolutions to add up to macro-evolutions. This requires many generations: more generations than occur within a human lifespan, even for small organisms with short lifespans.

That’s why evolutionary theory does not predict that we would see large visible changes from one kind of living being into another on the scale of human lives, and we don’t. The fact that we don’t does not refute evolutionary theory, because it is not a prediction that evolutionary theory makes.

The concept of transitional fossils is related, but it probably deserves its own post.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiocarbon dating
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils
Complexity – irreducible and otherwise

There are a range of arguments against evolution that rely on the notion that it is inherently so improbable as to be impossible. They date right back to William Paley, who published his ‘watchmaker argument’ in 1802, predating Darwin’s ‘Origin of Species’ by more than 50 years.

Essentially, this is the notion that the appearance of design implies the existence of a Designer. It’s also linked to the analogy of ‘a tornado in a junkyard creating a functional Boeing 747 aircraft’, and to the ‘infinite number of typing monkeys creating the complete works of Shakespeare if given an infinite amount of time’.

I’ve tried to avoid linking out to things elsewhere in this series and to make them self-contained, but this paper from 1971 in American Biology Teacher has a perfect example of the kind of thing I’m talking about, in the section entitled “How Many Genes Could Exist?”

Using the usual approach used in these kinds of arguments, that piece comes up with a probability of 1:10⁶⁰⁰ for the random evolution of all possible genes. That’s a genuinely outlandish number: to give you a sense, the number of atoms in the known universe is on the order of 10⁸⁰. If that number were correct, then indeed it would seem wildly improbable that life could evolve.

This short post is just about explaining why it is not.

First, that assumes entirely random processes without a step-wise process of natural selection. It assumes that it is necessary (to mangle a metaphor) to arrive at the Boeing 747 without passing via the Wright Flyer and successive improvements.

Second, it assumes that a specific outcome is the goal, whereas biology has a very large range of possible ways to solve the same problems. There are different kinds of wings and eyes and different types of legs and different models of fish locomotion and… Again, to play with metaphors, it’s not inevitable that the monkeys will arrive at the complete works of Shakespeare: they might end up with Stephen King or Iain M Banks or S T Colleridge instead.

These two objections may not sound like much, but together they essentially mean that the statistical and probability claims against the evolution of life do not hold water. Statistical models are only valid when they accurately model the phenomenon of interest… and these simply don’t.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiocarbon dating
Radiometric dating and deep time
Four Forces of the Universe
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils
Complexity – irreducible and otherwise

(This piece is a bit of a digression from the recent focus on evolution and its discontents, and moves back closer to my own comfort zone in physics. It is also at a high school physics level – the water gets much deeper than I’ve presented here very quickly, but this is a useful place to start.)

In discussions of the universe at the larger scale of cosmology and astrophysics – the formation and motion of stars and galaxies – I’ve recently begun encountering people who claim that ‘it’s all magnetism’, that every force in the end can be reduced to magnetism.

No doubt these voices have been around forever, and it’s just that I’ve started hearing them, but it’s a fascinating phenomenon. These people tend to be skeptics about General Relativity, and sometimes even about whether gravity exists at all. Certainly dark matter and dark energy are rejected passionately – it’s all magnetism!

I’m not sure what motivates it. Perhaps magnetism is the force that seems realest and most tangible. Most of us have played with magnets, and felt that real force, of both attraction and repulsion. It feels quite like the force of gravity holding us down – at least the attractive element does. And imagining a repulsive gravitational force is exciting! No heavy rockets needed to get to space if you’ve got anti-gravity!

As a bit of an antidote, I thought I might talk for a moment about the four fundamental forces that act in our universe. I might include a couple of equations for comparative purposes, but it should be quite easy to understand this post even if you ignore them.

The four forces are gravity, electromagnetism, the strong nuclear force and the weak nuclear force. (Newer physics links electromagnetism and the weak nuclear force together as the ‘electroweak interaction’, but that’s past where we want to go for the moment.)

The nuclear forces govern what happens inside the nucleus: the strong force is what holds the nucleus together in spite of the electrostatic repulsive forces between the protons, and the weak force governs radioactive decay. We won’t say too much more about them, except to note that the balance between the strong nuclear force and the electromagnetic force is what allows stable nuclei – and hence us – to form. Slightly different values of either would not allow matter to form. This has implications for whether divine fiddling with the speed of light or the rate of radioactive decay could happen, but that’s another story for another day.

Electromagnetism can be thought about as two things, although they are tightly tied together – electricity and magnetism.

We’ll take magnetism first. It’s fascinating, because it acts only on a moving charge. If a charged particle remains perfectly still in a magnetic field, no force acts on it. The formula is F = qvBsin(theta), where F is the force (newton), B is the magnetic field strength, q is the charge (coloumb), v is the velocity (metre per second) and theta is the angle (degrees or radians). As you can see, if v is 0, the force will be 0. The calculation is actually a ‘vector cross product’, and that tells us the direction the force will act in, but that’s also probably further than we need to go.

OK, we have enough already to reject the idea that gravity can be reduced to magnetism. We saw that if v is 0, F is 0, but also, if q – the net electrical charge on an object – is 0, the force will be 0. I don’t have a net electric charge on my body, neither do you, and neither does Earth. That means that the gravitational force holding me down on my chair as I type this is not a magnetic force.

(It’s possible the objection will be raised that the protons and electrons in my body have charge and are moving relative to those in the Earth, but again, there is not a net overall charge on an atom, and the directions of motion would all cancel one another out. And, of course, we now tend not to think of the motion of electrons in terms of the ‘orbit’ metaphor anyway…)

The other manifestation of the electromagnetic force is electrostatic attraction and repulsion, and this gets interesting. The formula is F=(kq₁q₂)/r² where F is the force, k is a constant, 9 x 10⁹ , q₁ and q₂ are the charges on the two objects and r is the distance between them.

The reason I said it gets interesting is that this has a direct mirror in the equation for gravitational force, F=(Gm₁m₂)/r² where G is a different constant, 6.67 x 10^-11 and m₁ and m₂ are the masses of two objects.

While the similarities are striking, there are also two important differences:

1. There are both attractive and repulsive electrostatic forces. Professor Paula Abdul had it right: opposites attract! And same charges repel. On the other hand, there is only an attractive force of gravity, not a repulsive one. Objects with mass always pull one another closer, never push one another away.
2. The relative strength of the forces. I haven’t included the units, but in terms of the normal SI unit conventions the constant for the gravitation force is about 1/10²⁰ or 0.00000000000000000001 times as large as that for the electrostatic force. Inducing a very small charge in a party balloon, for example, will allow it to stick to a wall in defiance of gravity.

So there you have it: a brief rundown of the four fundamental forces, and – in simple terms at least – some discussion of why we still need four, and can’t boil them all down to one.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiocarbon dating
Radiometric dating and deep time
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils
Complexity – irreducible and otherwise

If you haven’t yet read the Radiocarbon dating post, and if you’re not already au fait with the elements of half-lives and radiometric dating, it’s probably worth clicking on the link and reading that post first, then coming back to this one.

Radiocarbon dating can only take us back on the order of a few tens of thousands of years. Humans and proto-humans are believed to have been around for a couple of million years, the last dinosaurs to have become extinct about 65 million years ago, and the Cambrian to be about half a billion years ago. Earth itself is believed to be about 4.5 billion years old.

That means we need some other dating methods, and some of those also rely on radioactive decay. Carbon-14 has a half-life of 5730 years, but other radioactive elements have much, much shorter half-lives – on the order of nanoseconds or even femtoseconds – and some have much, much longer half-lives.

A few different methods and decays are used:

*This is the U-238 to Pb-206 decay, but there is also a U-235 to Pb-207 decay with a half-life of 700 million years that runs in parallel and can be used as an extra check.

The method is as for radiocarbon dating, but in most of these cases the ‘daughter nuclide’ – the second name in each of the pairs in the table, the thing that the first-name element decays into – is solid and stays around, unlike the nitrogen that is the product of radiocarbon dating. This means that the age is usually calculated in terms of the ratio of the parent and the daughter nuclide in the sample.

There are similar ‘gotcha’ examples sometimes used for these dates, but since many creationists are also proponents of a very short age of the Earth – some 6000 years in accordance with Bishop Ussher’s chronology based on the Biblical genealogies, some a little longer but not much – most would suggest that the planet¹ is younger than even the 80,000 years of a single half-life of the Uranium-Thorium decay.

That means that a common theme is “But you assume that the rates of radioactive decay has always been constant. Maybe it was different in the past.” Some suggest that at the time of Noah’s flood there was also a dramatic increase in the rate of radioactive decay.

The thing is, every radioactive decay reaction also releases heat. If there had been sufficient acceleration to fit 4.5 billion years worth of decay into 40 days and 40 nights (while it was raining (in the account)) or even a year (before the floodwaters subsided)), the heat released would have been sufficient to melt the entire planet, many times over.

The response I’ve sometimes received when raising that issue is “God has infinite power and could shield the Earth from the heat”. Well, I guess so, but that just piles ad hoc intervention on top of ad hoc intervention. If God wanted to do that, perhaps it would have been simpler just to specifically set the isotope ratios… and also do things like create the polonium halos in granite that certainly suggest radioactive decay occurred over a very long period.

My goal in these posts is really not to pick fights, but to enhance understanding of the relevant science. Occasionally, though, enhancing understanding involves addressing common misunderstandings.

1. Or life: beliefs differ, but even those who believe the planet has been around longer believe it was ‘without form and void’, so there were not features capable of being dated.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiocarbon dating
Four Forces of the Universe
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils
Complexity – irreducible and otherwise

A friend, in a discussion of the age of the Earth, recently said “I remember a study where there were some bones that were known to be only a few years old but they were carbon dated as being 8 or 9,000 years old”.

It helps to illustrate the problem: it’s someone’s recollection of something someone else told them some time ago, so there’s no citation, and few details. It’s difficult to check what actually happened. I found it then but can’t now, but there are a number of similar articles around, and we’ll get to the issues with them.

I thought today I’d talk a little bit about radiocarbon dating specifically (more on other forms of radioactive dating in coming days): how it works, what it can and cannot do, and why some of the common objections to it don’t really hold water.

Radioactive decay is a fascinating process. Unlike physical decay, it is not influenced by how hot, wet, pressured or otherwise its environment is. It is a process that appears random at the level of individual decays – it’s impossible to accurately predict when one will occur – but is highly predictable at a statistical level, when many decays are combined.

If a sample of a substance has, say, 1000 atoms of a radioactive chemical element in it, the meaning of the term ‘half-life’ is the amount of time taken for half of those atoms to undergo decay. The half-life for a particular type of decay to occur is constant. Say in our example the element has a half-life of 2 days. After 2 days, there are 500 atoms left (half the original amount). After 2 more days, there are 250 left (half as many as 2 days ago, quarter as many as were there originally, 4 days ago). After 6 days in total there are 125, after 8 days there are 62.5 (there are not really 0.5 atoms, so it would likely be 62 or 63). It will keep halving, each 2 days, until there are no atoms left.

The great majority of the carbon in our environment is carbon-12. It has 6 protons and 6 neutrons in its nucleus, for a total of 12 ‘nucleons’. Carbon-12 is stable and does not undergo radioactive decay. A very small amount of the carbon has an extra neutron for a total of 13. It’s called carbon-13 and is sometimes important in MRI scanning. Carbon-13 is also stable.

When neutrons in incoming solar radiation strike nitrogen-14 in the upper atmosphere it sometimes undergoes a tranformation into carbon-14, and carbon-14 is radioactive.

It later undergoes radioactive decay to release a beta particle and returns to being nitrogen-14. The half-life of this decay is 5730 years.

(An electron anti-neutrino is also released, and this equation isn’t properly charge balanced, and there’s an interesting reason for the minus sign for atomic number on the beta particle, but perhaps that’s too much detail for here.)

The carbon-14 in the upper atmosphere is distributed through the whole environment. Plants take it in when they use energy from sunlight to power photosynthesis, changing carbon dioxide and water into glucose and releasing oxygen. Living things either eat plants or eat things that eat plants, so all living things have carbon-14 in them. As long as they’re alive, they keep replenishing their stores of carbon-14, and so the amount in their bodies is stable. There are radioactive decays going on, but the supply is being replaced.

Once something dies, though, it stops breathing, stops eating, stops interacting with the environment. No new carbon-14 is added to its body, and what is there decays in a predictable way.

This is why radiocarbon dating can only be used on things that were formerly alive. It is not useful for dating rocks, or fossils (which are rock that’s replaced something that was formerly alive), or buildings, tools and other artifacts. Something had to be living, breathing, eating and drinking at some point in history to be able to be radiocarbon dated. There are other methods of dating other materials, that I’ll talk about in a different post.

The period of time that radiocarbon dating can stretch back is also limited. With a half-life of 5730 years, it’s very convenient for dating things that are low multiples of that, back to 25,000 years or so, but even at that point you’re 4 half-lives in and there’s only 1/16th of the original amount remaining. If you have a larger sample, so that the remnant is larger even after multiple halvings, radiocarbon dating can get you back 50,000 years or so, but not much further than that.

As a matter of perspective, there are artifacts of Aboriginal settlement in Australia that are older than that.

Radiocarbon dating is generally reliable. It makes some assumptions, but they are generally valid, or else able to be calibrated for. So, for example, if additional volcanic activity, or nuclear testing or other influences changed the amount of carbon-14 in the atmosphere at the period in which the formerly-living thing being dated was alive, that’s relevant: and can be taken into account. If additional carbon-14 has leached in or out of the sample, that’s relevant.

There are a few claims made by creationists, that are usually of the ‘gotcha’ type. They will have sent a sample to a lab with no information about what it is or where it comes from, requested dating, and then triumphantly revealed that the real known age is different. In all of these cases I have seen, including the one with which I started this piece, there is a clear, simple scientific explanation for the apparent disparity, which does not invalidate the method of radiocarbon dating for age determinations.

Often, the issue is that the organisms being dated were not in contact with the atmosphere in a ‘normal’ way. Examples include shells that grew in water from underground caves, where the carbon dissolved in the water in which they and their food grew had in many cases spent a very long period as part of limestone. The carbon-14 in it had long ago decayed already, so the carbon these shells were absorbing was depleted in carbon-14 relative to the ‘norm’ in other places. When comparing these shells to similar ones grown in fresher water, they appeared ‘older’ because they had lower levels of carbon-14.

When the science is done properly, the sample is tagged with the location where it is found, and these kinds of anomalies can be calibrated for. The ‘gotcha’ examples might give those seeking to impugn the method something to crow about, but they’re not good science.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Facts, Theories and Laws
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils
Complexity – irreducible and otherwise

(This piece is slightly modified from one originally published on the Adventist Today web page – apologies to those who have already ready it in other fora. More brand new words tomorrow!)

“Evolution is a fact” is something we tend to hear from one side in debates about origins. I’d argue that this statement reflects a misunderstanding of the roles of facts, theories and laws in science.

At the same time, from the other side of those same debates, we tend to hear “evolution is (just) a theory”, which is equally unfortunate as a way of thinking about what ‘theory’ means in science.

I want to, as clearly as I can, briefly outline the meanings in science of the terms ‘fact’, ‘theory’ and ‘law’, and to explain why a theory, no matter how well supported by evidence, never turns into a fact.

Evolution is, in some circles, a controversial theory, and therefore a bit awkward to use as an example for this discussion, since it brings in strong emotions and strongly held views on the part of readers. (And, just quietly, I’m a physics guy, not a biology guy.) So, instead, I’ll use the example of gravity.

Here is a fact about gravity: close to the surface of the earth, if any object (that has mass) is unsupported, it will accelerate toward the centre of the earth with an acceleration of about 32 feet per second per second, or about 9.8 metres per second per second. If you have an object and a stopwatch handy right now (and your phone probably has a stopwatch function), and have done a little high school physics, you can test this fact.

In science, ‘fact’ is used to refer to a single piece of data, the result of a measurement. Other facts about gravity include the fact that it decreases in strength as we move away from the centre of the earth, and that every object that has mass exerts a gravitational force on every other object that has mass. With sophisticated-enough instrumentation, all these facts can be measured and expressed in numbers.

Not all of science is physics, though, as my students often remind me. It’s a fact in chemistry that sodium chloride (table salt) has a cubic lattice structure between its atoms, and a fact in biology that living things contain DNA, and a fact in geology that most rocks contain a lot of silicon dioxide.

Let’s leave ‘theory’ on the side of our plate for the moment, because it’s the most complicated, and talk about ‘law’. In science, a law is a mathematical relationship between quantities. The most famous law in science is probably Einstein’s E = mc2, which describes the relationship between matter and energy.

The key law in gravity, which was formulated by Isaac Newton (and I do apologise for those who find equations challenging!), is F = (Gm1m2)/r2 In words, it says that if there are two masses, m1 and m2, a distance r apart, the force F between them is given by this law, where G is called the ‘universal gravitational constant’.

A law is powerful because it makes a relationship clearer. A couple of paragraphs ago I said that the force decreases with distance, but the law gives more detail. It shows that the force decreases with the square of distance: if the objects are 2 times as far apart, the force is only ¼ as great.

A theory is a human mental creation that explains facts and has withstood the test of experiment. This view of the nature of science and of theory is owed to philosopher of science Karl Popper. A theory in science has descriptive, predictive and explanatory power. That is, a theory describes the world as we see it and experience it. It allows us to reliably predict how the world will behave in future in a particular set of circumstances, and it explains why the world is as it is. If we make a prediction using a theory, and then conduct the experiment and the prediction fails – the world does not behave as the theory leads us to expect – then Popper would say the theory has been ‘falsified’ and should be discarded. The theories that make up science at any given moment are the ones that have been tested many times and have never been falsified. Einstein neatly summed up Popper’s perspective: “No amount of experimentation can ever prove me right; a single experiment can prove me wrong”.

A theory is not held to be ‘true’ in any final sense under this view: at best, it is the most powerful theory available, that explains the greatest number of facts, and has not been falsified. A new experiment may yet be conducted that will falsify it, and if that occurs the theory will need to be discarded and replaced with a better one.

The first – and longest-lived – theory used to explain our experience of gravity was proposed by Aristotle. He suggested that things in the universe have their ‘natural station’, the place where they belong. Things mostly belong on the ground – even birds – so when we lift them above the ground they are being lifted out of their natural state, and if they are not prevented from doing so, they will return to it. If we lift a book from the floor to a table, it is out of its natural place, and if the table were not there to prevent it doing so, the book would return to its natural place on the floor.

Aristotle’s theory of gravitation applied only on Earth, since he also believed that the heavens were a different domain from Earth, with different rules and processes. The contribution of the next great theorist of gravity, Isaac Newton, was to apply the same rule to objects in space like the moon and the planets that was used to explain how things move on Earth.

Johannes Kepler had created rules that described the motion of the planets in purely mathematical terms, but did not explain why the planets moved the way they did. Most times laws are derived from theories, but we could argue that Kepler’s laws were not drawn from a theory. They had descriptive and predictive power – Kepler could tell you when the next eclipse would come – but not explanatory power. Newton developed the theory that any two objects with mass exert a force on each other, and – crucially – that this is true in the heavens as well as on Earth. The same force that caused his (probably apocryphal) apple to fall from the tree to the ground explained the motions of the heavenly bodies. Newton had a theory, not just a law, because in addition to description and prediction, it was capable of explanation. Newton’s theory of gravity still works well for everything we encounter in everyday life, but for much more extreme environments, such as near the event horizon of a black hole, it breaks down. For those specialised contexts, it has been replaced by the theory of General Relativity proposed by Albert Einstein. The mathematics gets very complex very quickly, but in words, Einstein’s theory can be stated as ‘matter tells space how to curve, space tells matter how to move’. Gravity is explained, not as a force between objects, but as mass causing curvature in the local space, which then causes mass to move differently.

Einstein’s theory is considered ‘better’ than Newton’s because it is more universal – it can be applied everywhere in the universe, whereas Newton’s theory breaks down in some situations.

All three of the theories described – Aristotle’s, Newton’s and Einstein’s – explain the fact that a dropped book or apple will fall toward the ground. Aristotle’s does not have an associated law – a mathematical statement about how rapidly the apple will fall – while Newton’s theory does include a law. Einstein’s theory also includes laws, but the mathematics are too complex to go into here.

I hope these examples have helped to explain why a theory can never turn into a fact or a law, no matter how much evidence it has behind it. These are three different things with different qualities, each important in science.

I suspect that when someone says “evolution is a fact”, they are using the word ‘fact’, not as a scientist would, but in the everyday sense of ‘not fiction’. They mean that a textbook on evolutionary theory in the library would not be placed with the novels and short stories, but with the other books that contain true information about the world. It’s probably still an unfortunate usage, though, since the claim being made falls within science, so the language used ought to be the careful language of science.

Evolution is a theory. It is one that explains, not one fact, but an enormous variety of facts about the diversity and the characteristics of life on Earth. It is a theory that was proposed more than 150 years ago, and it has been tested in a wide variety of ways. The fundamental concepts have not been falsified, but significant elements have been changed and updated. Darwin did not know about genes when he wrote ‘On The Origin Of Species’, for example, or DNA. He did not have access to the vast array of data about living things that modern scientists can draw on. The modern evolutionary synthesis includes the recognition that gene transfer plays a much greater role than previously thought, for example, so that less of the ‘heavy lifting’ of generating new characteristics must be borne by mutations.

When people say “evolution is (just) a theory”, they are drawing on the common, everyday use of the word, rather than the scientific use. We say “I have a theory” when we mean a guess, a hunch, an untested brainwave. Saying “evolution is a theory” is thought of as a way of saying that it is unsupported, held without evidence, untested. These same people would tend not to say “gravity is (just) a theory”, although in scientific terms, gravity is indeed a theory. Or, at least, there are multiple theories of gravity that explain the facts of gravity, some of which provide mathematical laws, and Einstein’s is currently the best theory we have.

Theories do change, and Einstein’s theory may well be replaced by an even more powerful one in the future. There are interesting problems at the boundaries between General Relativity and quantum theory, for example, that may revolutionise our understanding in the future. But a book will still fall from a table, and an apple from a tree. A change to the theory of gravity will not enable us to suddenly, unaided by technology, safely walk off the roof of a tall building and just float. The facts of gravity will remain the same if the theory used to explain them changes.

The same is true of evolutionary theory. It has changed in the past and is likely to continue to change. Alternative candidate theories, including special creation and intelligent design, already exist, and already claim to explain the same facts. When the theory changes, the facts will not change. The DNA that forms the genetic blueprint for a jellyfish will not suddenly begin to produce a lion instead.

It’s probably a discussion for another article, but to date the alternative candidate theories – special creation and intelligent design – have not demonstrated descriptive, predictive and explanatory power in the same ways and to the same extent as the modern evolutionary synthesis. There are efforts to make these demonstrations, which will continue to be tested against the facts of biology.

I hope this brief discussion has been helped you to understand the meanings of the terms ‘fact’, ‘theory’ and ‘law’ in science, and to be aware when these terms are being used confusingly in discussions around origins as well as other scientific topics such as vaccination, genetic modification and climate change. If we can communicate clearly and accurately, and go forward together in good faith, we have more chance of finding our common ground.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Evolution and entropy
Radiocarbon dating
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils
Complexity – irreducible and otherwise

The claim is sometimes made that entropy, or the laws of thermodynamics, prohibit the possibility of evolution.

The laws of thermodynamics can be stated in a number of ways in words, and more precisely in equations, but here is one way of stating them:

1. Energy cannot be created or destroyed in an isolated system.
2. The net entropy of an isolated system always increases.
3. The entropy of a system approaches a constant value as the temperature approaches absolute zero (-273.15^o C).

A more amusing but less accurate version I have seen is:

1. You can never win, you can only break even.
2. You can only break even at absolute zero.
3. You can never reach absolute zero.

Returning to the first set of laws, the First Law obviously needs to be slightly modified in the light of General Relativity and Einstein’s famous equation E = mc² to ‘matter-energy cannot be created or destroyed’, but the bottom line remains the same.

Entropy has a technical definition, or rather a number of different technical definitions, expressed in equations, but it is often understood as the ‘disorder’ of a system. So an increase in entropy is a decrease in order, and so on. Essentially, energy tends to change from more useful forms, that can do work, to less useful forms, over time.

The claim I referenced in the first sentence – that entropy forbids evolution – relies on the notion that evolving from a single-celled organism to something like a human being (with a human brain, perhaps the most complex matter we know of) requires a considerable increase in order, and therefore a net decrease in entropy.

The answer is right there in the Second Law, though: the words ‘in an isolated system‘. A single-celled organism does not evolve into a human being if it is placed in a sealed chamber and isolated from incoming energy – in the forms of heat, light, food and air – from the environment.

Perhaps the people who make this claim want to regard the whole of Earth as an isolated system, and argue that the evolution of all lifeforms from simpler (less-ordered) lifeforms is prohibited by the Second Law of Thermodynamics?

But the answer to that involves stepping outside and looking up, even on a cloudy day. Earth is not an isolated system, because it receives vast amounts of energy from that big nuclear fusion generator in the sky, the Sun.

Local increases in order – decreases in entropy – are certainly not prohibited: a human brain is much more ordered than all the food that goes into making it.

In practical terms, no system in the universe is closed and isolated. Even the Solar System emits solar energy to the space around it. But certainly, in considering Earth, the energy coming in from the Sun is a huge part of the overall energy picture.

(As a side note, high energy, short wavelength visible light arrives with the ability to do work, including the work of photosynthesis. It passes through various processes, and then is emitted as low energy, long wavelength infrared radiation, which radiates off into space. Unless intercepted by greenhouse gases, in which case it hangs around a bit longer, warming the globe…)

And it turns out that the nuclear fusion process of hydrogen combining to form helium that produces the Sun’s energy involves a net increase in entropy – a net decrease in order. And, given that Earth receives only a tiny fraction of the energy the Sun puts out, this increase in entropy occurring in the Sun completely dwarfs the local decrease in entropy involved in evolution. So, in the local system of our Solar System, net entropy increases, in agreement with the Second Law

No rules of thermodynamics are contravened by the processes of evolution.

For ease of navigation I will include links to each of the other posts in this series at the bottom of each post.

Why I think it’s important to understand evolution
Cosmogenesis, abiogenesis and evolution
Facts, Theories and Laws
Radiocarbon dating
Radiometric dating and deep time
Four Forces of the Universe
Probability and evolution
Species and ‘baramin’, macro- and micro-evolution
Mitochondrial Eve and Y-chromosomal Adam
Transitional fossils
Complexity – irreducible and otherwise