Wednesday, September 20, 2006

Age of the Earth Series - 4

Lecture 4 - Creationist Arguments for a Young Earth

In Lecture 3, we dealt with the major creationist arguments against radiometric dating, and we showed just how poorly informed they are - and just how poorly informed they rely on their audience being to succeed. When held up to the light of scientific fact, and how radiometric dating is actually done, they are either very naive, or just plain contradictory to the facts of the matter.

I hope that are you read this lecture, and you see just how poorly informed creationist arguments for a young earth are, you start to ask yourself a very important question: how can it possibly be that they've got their science this wrong? Many of the arguments I am going to present here have been around since the writing of Henry Morris' text, "The Genesis Flood", in the 1960s. Since then, they have been formally rebutted many times - sometimes in front of such esteemed audiences and the US Supreme Court (in Mclean vs Arkansas Board of Education in 1981, for example - the landmark ruling from which can be found here - and God bless America).

Then you should ask yourselfs, given the poverty of these arguments, their factual errors and naive assumptions - and their many, varied and public rebuttals - why is it that you can go online to google and find them all on countless creationist websites? Why is it that young adults and adults alike "challenge" me with them when I tell them I believe in an old earth, even to this day?

I'm sure as you ponder these questions that you will come to the same conclusion as I have, as Judge William Overton did in 1981, that creationists are not interested in truth, or in scientific discovery, but rather have already come to their conclusions and refuse to change them no matter what the evidence says. As the judge himself put it in his concluding statements:

"The Creation Research Society employs the same unscientific approach to the issue of creationism. Its applicants for membership must subscribe to the belief that the Book of Genesis is "historically and scientifically true in all of the original autographs" (28). The Court would never criticize or discredit any person's testimony based on his or her religious beliefs. While anybody is free to approach a scientific inquiry in any fashion they choose, they cannot properly describe the methodology as scientific, if they start with the conclusion and refuse to change it regardless of the evidence developed during the course of the investigation."

I say it again, God bless the First Amendment, God bless the Lemon Test, and God bless the United States of America.

Argument 1: Salt goes into the seas and oceans from rivers every day. At the rate that salt is being added to the seas, they cannot be more than 10,000 years old.

Firstly, it's worth knowing that the seas have many different types of salts in them. For the more reactive salts, if you calculate the ammounts in the seas today, and the divide by the ammounts added per year, you get an "age" of the earth as only a few hundred years old. And other salts give an "age" of many millions of years old. Clearly this cannot be a good way of telling the age of the earth - we know it isn't really a few hundred years old.

So what is the matter with this method? The simple answer is that there is a "saline cycle". Anyone knows that if you keep adding salt to a glass of water, no matter how hard your stir, the salt will eventually precipitate at the bottom of the glass. The same happens in the sea, salt precipitates, how fast it does this depends on the reactivity of the salt. The salt and other sediment then forms layers on the sea bed - and either ends up being uplifted above sea level to form mountains and new land (creating the streams and rivers that then deposit it into the seas again) - or subducted into the earth's crust, and recycled eventually in volcanic activity - hence the high salinity of volcanic streams.

The reason we get a high discordance between salts is that we are not measuring the age of the seas, but the residence time of the salt. The more reactive salts precipitate quicker and therefore leave the seas quicker, and are recycled more often. These give very low residence times, whereas the less reactive salts give higher residence times. This argument and its rebuttal appears in Science and Creationism, by Ashley Montagu, first published in 1981 in reaction to Mclean vs Arkansas Board of Education, 3 months before I was born. If you search today, 25 years later, just as I am about to take out my first mortgage, it still appears on many creationist websites. You will find this same sad truth with all the arguments rebutted here.

Argument 2: Planets and stellar bodies collect dust as they move through space. If the moon had been around for billions of years, it would have collected hundreds of feet of dust, which would never have been moved or cleared.

This argument is very popular, and is often accompanied with a mythological account of how NASA expected their lunar lander to sink in the hundreds of feet of dust they thought they would find on the moon. It is also based on data taken in the 1950s, on earth, of how much interstellar dust we encountered. Although this measurement was taken in a remote area, and at high altitude, it was not taken in space itself, and was orders of magnitude out.

However, as you can all imagine, the ammount of dust collected in space is hugely important to NASA and other space agencies, because it affects the efficacy of satellites. And, as you can also imagine, NASA have now made direct measurements in space. In fact, they made them in the 1970s, over 30 years ago. Using these figures (please email me if you want the details of the maths) the depth of dust found on a 3.5 billion year old moon is only a few inches, which is the actual depth found.

Of course, this doesn't mean that this is an accurate way of telling the age of the moon - there is no evidence that the ammount of interstellar dust has remained the same over the years. But it is nevertheless interesting that taking accurate data, as opposed to data that is hundreds of times out from the truth, we arrive at a fairly accurate age for the moon.

Argument 3: The earth's magnetic field is decaying. Had this been occuring for billions of years, that would mean the initial field was impossibly high.

This is a classic creationist argument. Classic because, once understood in the light of scientific evidence, it actually turns into yet another evidence for an old earth, and yet more proof of antiquity of the geological record.

It is true that the earth's magnetic field is getting smaller. But it is reversing, not decaying. It's flipping over. In a few thousand years, our compasses will point south, weird as this may be, hard as it might be to believe. These reversals have occured hundreds of times during geological history.

How do we know this? Were we there to measure the field millions of years ago? The answer is no, of course, but fortunately the rocks were there to measure it for us. Many rocks and minerals contain iron - which is a magnetic material. When a rock containing iron solidifies, all the iron atoms align themselves to the direction of the earth's magnetic field at the time. The rocks becomes a "little magnet" - its iron atoms are pointing in the direction of the current magnetic field.

As we dig down the geological column, we find that all of a sudden, the direction of these rock's magnetic fields switch suddenly. Then switch again. Then again. Over and over - hundreds of these reversals of the earth's field are known throughout geological history. And we're due one, and we have the privelege of living through one now in order to study it.

We still do not know why these reversals happen - but what we can say for certain is that the so-called "decay" of the earth's magnetic field is certainly not a good way of telling the age of the earth. And we can say that the earth must be many many times older than creationists state, in order to accomodate the hundreds of known reversals of the field in geological history.

Argument 4: The moon is receding from the earth every year - it is getting further away. If the moon is billions of years old - the moon would have been touching the earth, and this is impossible.

Firstly it is important to understand that the moon is getting further from the earth, because it is having energy transferred to it from the earth's rotation and through tidal forces. The newtonian mathematics of this is beyond the scope of this discussion, but it's true that the moon is an will recede from the earth.

It is ironic though that creationists, who always accuse scientists of making "uniformitarian" assumptions - should be the ones who always assume that things now are as they were in the past. The moon is receding at 6 inches a year, giving about 2 billion years in the past before it reached the "Roche Limit", at which point it would break up (the Roche Limit is a limit for the closeness of two liquid objects before the gravity of one would destroy the other - since the moon was probably molten at the time of its creation, it must have been created beyond the Roche Limit).

Now, the moon is 3.5 billion years old - so the question is, has it always been receding at 6 inches a year. The answer is "no". As Hansen 1982 pointed out, "The present rate of tidal dissipation is anomalously high because the tidal force is close to a resonance in the response function of the oceans; a more realistic calculation shows that dissipation must have been much smaller in the past and that 4.5 billion years ago the moon was well outside the Roche limit".

In other words, more energy is being transferred to the moon now from the tides than is usually the case (for the mathematics behind the concept of "resonance" please email me). There is therefore no problem with a 3.5 billion year old moon.

Argument 5: The Moon contains considerable quantities of U-236 and Th-230, both of which are short-lived isotopes that would have expired long ago if the Moon were 4.5 billion years old.

This is one of the poorest informed creationist arguments around, worse perhaps than those that have preceeded it.

Thorium-230 is a direct decay product of Uranium-238 - which has a half life of over 4 billion years. It is therefore being constantly produced on the moon and elsewhere by long lived isotopes. Uranium-236 is also being constantly produced by neutron capture in some Uranium ores. Therefore there is no problem with the existence of either on the moon or elsewhere that long-lived forms of Uranium exists.

These are not isolated arguments. A common version these days is C-14 existing in coal samples and oil deposits. This can be found in the recent paper from the Institute for Creation Research's "RATE" team - a team set up to prove that the earth is young. The first irony of this argument is that it appeared in the same paper that hypothesised that during the flood rates of decay had been massively accelerated. We dealt with this argument in the last lecture - but isn't it funny that in the same paper - creationists should advance two mutually exclusive arguments: one that the earth is young because decay rates have been massively accelerated - and one that the earth is young because C-14 exists in coal and oil, C-14 that shouldn't exist if decay rates had been massively accelerated.

Again, the answer to this latter argument is similar - that near other radioactive sources C-14 can be generated from ordinary carbon materials.

Argument 6: The sun is shrinking at 5 feet/hour which limits the earth-sun relationship to less than 5 million years.

There are two major problems with this argument. The first is that suns do not expand and contract at the same rate throughout their stellar evolution. It's a little like watching the tide go out and concluding that the water level must have fallen at that rate since the earth began. Therefore, working backwards, much of the land must have been under water a few weeks ago! Since careful inspection shows no signs of such a flood, the earth can't be older than a few weeks!

In other words, the shrinking-sun argument rests squarely on a naive extension of a rate measured over a relatively short period of time. It's the type of blunder one might find in a high school science project. The second assumption is that there is scientific consensus as to what the change in the sun's diameter is per year. In fact, the data that creationists are using "5 feet per year" - was only ever published in abstract form, and has since been heavily discredited.

Argument 7: The rates of erosion / land formation are too high

Amazingly, both these argument appear in the same Chapter of "The Genesis Flood" by Henry Morris, father of modern creationism. The fact that my viewers have by now probably figured out that the arguments cancel out, in that erosion and land formation are competing forces, is part of the tragedy of the creationist mindset - that they cannot see what is in front of their faces because they have already drawn their conclusion.

Now, the reality is that at any one time, erosion or land formation is likely to dominate - one is likely to be higher than the other at any one measurement. Anyone who's ever played SimEarth will realise this. But the way it is today isn't necessarily the way it's always been - and both these forces oscillate to destroy land and create it in roughly equal portions over geological time.

Argument 8: Marine fossils on top of mountains proves that the geological column was created in Noah's flood.

This is another popular creationist classic. The irony here is that one of the original papers explaining this phenomenon was written by Charles Darwin himself after his Voyage on the Beagle, the nemesis of the creationist.

Darwin found from measurements of the height of mountains and geological features, that mountains were not constant features of the environment, but were constantly uplifting and down-dropping. Although Darwin didn't know it, the forces behind these uplifts and downdrops were caused by tectonic plates moving and colliding. The modern day Himilayas were formed from the Indian subcontinent crashing into Eurasia, forcing rock from both up the way, and causing Everest and its partners.

The earth is an amazing and ever changing place, where sea beds can become mountain tops, and vice versa, in the course of the millions of years of geological history. Sadly, those who believe that the earth is only a few thousand years old miss this amazing history in their reckoning, and therefore miss out on the wonder of creation. In our next lecture, we will expand on this concept, and talk about how an Old Earth and modern science deepens our understanding of the divine, and fits in with all but the most naive and literalist theology.

Sadly we have not had time to go through every creationist argument here, but I'm sure you get the idea, and if you have another you want answered, feel free to post it up in the comments section and I'll do my best.