Bad Astronomy: Misconceptions and Misuses Revealed, from Astrology to the Moon Landing "Hoax" - Philip Plait (2002)
Part IV. Artificial Intelligence
Chapter 19. In the Beginning: Creationism and Astronomy
here is a story, almost certainly apocryphal, about a scientist who was giving a public lecture on astronomy. He was describing the scale of the universe, starting with the Earth orbiting the Sun and working his way up to galaxies orbiting other galaxies, and eventually the structure of the universe as a whole. When he was done, an old lady stood up and challenged him.
"Everything you just said is wrong," she claimed. "The Earth is flat, and sits on the back of a giant turtle."
The astronomer knew immediately how to retort to that statement: "But then, dear lady, on what is that turtle standing?"
She didn't bat an eye. "You're clever, sir, very clever," she said. "But it's turtles all the way down!"
I've always liked that story. Most people think it's about a silly old woman who doesn't understand anything at all about science. But I wonder. It's not too hard to play a little role reversal. After all, is her answer any more silly than saying that the universe started out as quantum fluctuation that caused the violent expansion of space-time itself?
Okay, yes, it is sillier. But the scientific explanation of the universe, although steeped in observation and tempered through the scientific method, may sound pretty silly to someone not well versed in the subject. The philosopher Pierre Charron said, "The true science and the true study of man is man." But in a very real sense, man is a part of the universe. I think, after 400 years, we can update Charron's statement: The true science and the true study of man is the universe.
We've been asking basic questions about our existence for a long time. Why are we here? Does the universe have meaning? What is our place in it? How did it all begin? These are questions of the most fundamental nature that everyone asks at some time. People turn to all manner of oracles for answers-religion, science, friends, recreational drugs, even television, although TV usually raises more questions that it answers.
That last question is the real poser. How did the universe begin? Everything in our lives has a beginning and an end. Stories start, build, reach a climax, then finish. Pictures have borders, symphonies have first and last movements, vacations have a starting and stopping point. Of course, our lives themselves are framed by birth and death. We experience everything one second at a time, an orderly flow from early to middle to late. We expect the universe to reflect our conditioning, that it had a beginning and that it, too, will eventually end.
Of all the philosophical questions, this one may actually have some scientific meaning. The clues to the beginning are there, if we can decode them. The universe is like a giant book, and if we are smart enough, we can turn the pages and read it.
To push this analogy just a little further, the next question might be, "In what language is the universe written?" This question is at the heart of a lot of debate. It may not surprise you that I think the universe follows a set of rules-physical and natural rules. These rules are complex, they are not clear, and it is beyond doubt that we do not understand all of them, or have even imagined what they could be. Some are simpler, like the behavior of gravity. Others are complex beyond our mind's capability, like how matter can disappear down a black hole, or just why an electron has a negative charge. But no matter how simple or how complex, the language of the universe is physics and math. We learn this language better as we observe phenomena around us.
Some people, though, do not think this way. They presuppose a set of rules and try to get their observations to match what they want to believe. This isn't a great way to try to figure out the universe. You wind up having to throw out observations that don't match your beliefs, even if those observations are showing the universe's true nature.
Such is the case for a minority sect of Christianity who call themselves Young Earth Creationists. This is a vocal minority, however, and their cries are heard loudly in the United States. They believe that the Christian Bible is the inerrant Word of God, accurate in every detail and the only way to judge observations. They believe that anything that does not agree with what is written in the Bible is wrong. Moreover, the Bible is not really up for interpretation: what it says, goes.
One faction of the young-Earth crowd is the vociferous Institute for Creation Research, or ICR. They are dedicated "to see science return to its rightful God-glorifying position," and they can be considered to be as official a mouthpiece for creationism as there is.
On their web site (http://www.icr.org) is an essay about the age of the universe. In it, Dr. John Morris, the president of the ICR, says that "every honest attempt to determine the date [of creation], starting with a deep commitment to the inerrancy of God's Word, has calculated a span of just a few thousand years." The Bible thus strongly indicates that the universe is very young. The whole of creation was formed in just six days, it says, and it's possible to get a direct lineal descendency from Adam to historical figures we know existed two thousand years ago. It's difficult to get an exact figure from the Bible, but it's clear the number is far, far smaller than the figure physical science would give.
There is a vast amount of data from many different fields of science that indicate the Earth is about 4.55 billion years old. It is not in the scope of this book to detail that information; I instead refer you to any good textbook on astronomy, geology, biology, or physics. My point here is not to show that the scientific view of the age of the Earth and the universe is correct; I will take that as a given. It is the creationists' contention that the universe is young that I challenge here. I'll do more than that. I'll say it quite simply: The young-Earth creationists are wrong. Utterly and completely.
Creationists usually rely on the Bible for their evidence. They are welcome to believe the Bible is inerrant if they so desire. However, they have lately turned to actual scientific findings to support their claims. But every argument they make is incorrect or incomplete. Every single one. They misinterpret scientific data, willfully or otherwise, and in their writings they only mete out enough information to support their argument, without giving all the data needed to make an informed decision.
I have no intention of discussing their arguments based on the Bible. I leave that to experts on religion and interpreting various ancient texts. I also have no desire to insult, denigrate, or argue against anyone's religious beliefs, as long as they do not use scientific data incorrectly to support these beliefs.
Creationists like to say that they practice "creation science." But this name itself is inaccurate; what they do is not science at all. Science is a matter of observation, data, and fact. Religion is a matter of faith and belief. The creationists start with the idea that the Bible is correct, and that any observations of the universe that do not agree with it must be wrong. That is not science; that is dogma.
If some particular scientific observation supports a particular religious belief, that's fine. But when that observation is distorted or misused in some way, that is not fine. It is when creationism and science overlap that things get dicey. I won't argue with their belief, but I will happily discuss creationist arguments based on astronomical observations.
The astronomical arguments they use to support their belief in a young universe can be found in their books, religious tracts, and on many web sites. They make dozens of arguments trying to support their untenable position, far more than can be covered in a single chapter of a book. Still, a few of the most common are worth dissecting.
I want you to remember as you read this chapter: these are the challenges the ICR itself and other creationists use against science. These are not straw-man arguments I made up, ideas easy to tear down to make the creationists look bad. These are their own weapons, and evidently unbeknownst to them, they are all aimed squarely at the creationists themselves. I have quoted their arguments below, and in some cases have paraphrased them slightly to make them more clear.
The age of the earth and moon can not be as old as required [by mainstream science due to] the recession rate of the moon (quoted from http://www.icr.org/pubs/imp/imp-110.htm).
A common creationist claim is that the way the Moon's orbit is changing shows that the Moon and the Earth must be very young. Certainly, they say, the Moon is no older than about a billion years, far younger than the age mainstream science declares.
You might think the Moon keeps a constant distance from the Earth, but this turns out not to be the case. Due to the complicated dance of gravity, the Moon's distance from the Earth actually increases by about 4 centimeters (1.6 inches) or so a year (for details, take a look at chapter 7, "The Gravity of the Situation: The Moon and Tides"). This number is well determined, because the Apollo astronauts left reflectors on the lunar surface that can be used by Earthbound astronomers to measure the Moon's distance quite precisely.
If you divide that distance-400,000 kilometers-by the recession rate of 4 centimeters per year, you see it would take the Moon 10 billion years to reach its present distance, assuming it started its journey somewhere near the Earth. However, that naively assumes that the 4-centimeter-per-year rate of recession is constant. Actually, that rate decreases rapidly with distance; the farther the Moon is from the Earth, the more slowly it recedes. In other words, in the distant past the Moon was much closer to the Earth, and receded faster.
If the calculation is performed more carefully, using numbers accounting for this change in the recession rate, you get an age for the Moon of much less than 10 billion years. One creationist, Don DeYoung, found that the Moon can be no older than about 1.5 billion years, and he claims that this is an upper limit to the age. According to him, the scientists must be wrong to claim an age of 4.5 billion years for the Moon.
But, again, the creationists are wrong. DeYoung assumed that you could simply extrapolate the Moon's current recession rate backwards in time all the way to when it was formed. As usual in the universe, things are more complicated than that. The current rate is actually much higher than usual. The rate depends on how well the Moon interacts gravitationally with the Earth.
The Earth and the Moon interact like a complicated mechanical watch, full of gears; if one slows down, they are all affected. So it is with the Earth and the Moon. The Moon's gravity moves water around on the Earth, causing the tides. This water rubs against the ocean floor, generating friction. That friction takes energy away from the Earth, slowing its rotation, and gives it to the Moon in the form of orbital energy. When the orbital energy of an object is increased, it moves into a higher orbit, so the Moon moves away from the Earth. The increased distance also means the Moon's orbital speed slows.
At this point in history, the Moon's orbit and the Earth's rotation collude to generate a lot of friction with the sea floor, especially near the shorelines of the continents. An unusually large amount of energy is being taken out of the Moon's orbit, causing it to recede faster than it normally would. In a sense, the Moon's gravity has a better grip on the Earth now than it did in the past, and is better at losing its own orbital energy.
What this means is that you cannot say that the current rate of 4 centimeter per year is a good average. In the past, the rate was actually slower than this, making the Moon older. DeYoung's estimate of an upper limit to the Earth's age actually turns out in reality to be a lower limit, and in fact is perfectly in concordance with an age of the Earth and the Moon of 4.5 billion years.
Beyond our Earth, the creationists see our very system of planets itself as an indication of the Earth's relative youth.
Astronomers have a pretty good idea about how and when the solar system formed. There have been many theories over the centuries, but repeated observations have indicated that the solar system formed about 4.5 billion years ago (which dovetails nicely with the age of the Earth/Moon system as well). Initially, the solar sys tem started out as a vast cloud of gas and dust. Something caused this cloud to collapse. Perhaps it was a collision with another cloud (which happens fairly often in the Galaxy), a blast from a nearby supernova, or the wind from a red giant star that pushed on the cloud that prompted the collapse.
Whatever the initial cause, as it collapsed, the cloud flattened due to centrifugal force and friction. As the matter in the cloud formed a disk, particles of ice and dust collided, stuck together, and grew. Eventually, over some hundreds of thousands of years, the pieces grew large enough to attract material with their own gravity. When this happened, the disk particles were quickly sucked up by the forming planets. By this time, the Sun was finishing its own formation, and a super-solar wind started. This wind blew any remaining material away, leaving something that looked a lot like the solar system we see today. This theory has recently been strongly supported by many astronomical observations, including those of young solar systems by the Hubble Space Telescope.
The creationists, however, say that the solar system shows several characteristics that are not consistent with the scenario outlined above. The ICR has an educational course available through its web page called "Creation Online," available at http://www.creation online.orglintro\08\8680.htm. In it, ICR officials list several of these arguments. All of these claims are wrong. What follows are verbatim quotations from "Creation Online."
If the planets and their 63 known moons evolved from the same material, they should have many similarities. After several decades of planetary exploration, this expectation is now recognized as false.
Actually, this claim is false. The disk that formed the solar system was not homogeneous; that is, it wasn't the same throughout its extent. That would be a silly thing for a scientist to assume, since it's clear that near the center of the disk the Sun would heat the material, evaporating off the ice, while near the edge far from the Sun the ice would remain intact.
Astronomers have known for decades that the disk must have had different materials distributed along it, because the outer planets and moons are much different than the inner ones. The outer moons have more ice in their composition, for example, perfectly consistent with a disk that had a distribution of materials along it. To be generous, this argument is at best disingenuous on the part of the ICR. If the collapsed disk theory hadn't jibed with that most basic observation, it would have been thrown out before it ever got proposed.
Since about 98% of the sun is hydrogen or helium, then Earth, Mars, Venus, and Mercury should have similar compositions. Instead, much less than 1% of these planets is hydrogen or helium.
When they formed, the inner planets probably did have a much higher amount of these gases. However, the gases are very lightweight. Imagine flicking your finger on a small pebble. It goes flying! Now try that on a station wagon. The car won't move noticeably, and you may actually damage your finger. The same sort of process is going on in the Earth's atmosphere. When a molecule of nitrogen, say, smacks into a much smaller hydrogen atom, the hydrogen gets flicked pretty hard, like the pebble. It can actually pick up enough speed to get flung completely off the Earth and out into space. When the nitrogen molecule hits something heavier, like another nitrogen molecule, the second molecule picks up less speed, like the station wagon in our example. It pretty much stays put. After a long time, the lighter atoms and molecules suffer this same fate; they all get flung away from the Earth. Over the lifetime of the Earth, all of the hydrogen and helium in the atmospheres of Earth, Venus, and Mars have basically leaked away, leaving the heavier molecules behind.
Jupiter and the other outer planets retained their lighter elements for two reasons: they are colder, and they are bigger. A colder atmosphere means the collisions occur at slower speeds, so the lighter elements don't get lost to space. A bigger planet also has more gravity, which means the planet can hold on more tightly to its atmosphere. A small hot planet like Earth loses its hydrogen; a big cold one like Jupiter does not.
So the collapsing cloud theory predicts that initially the planets may have had a lot of hydrogen and helium in their air, but it's natural-and makes good scientific sense-that some don't anymore.
All planets should spin in the same direction, but Venus, Uranus, and Pluto all rotate backwards.
According to the collapsing-cloud theory, the planets should all spin in the same direction in which they orbit the Sun because the initial disk spun that way. Anything forming in that disk should spin in the same direction. However, Venus rotates backwards, and Uranus rotates on its side! How can the disk theory explain that?
Actually, the answer is simple: it doesn't. The disk theory concerns only how the planets formed and not necessarily how they look today. A lot can happen in 4.55 billion years. In this case, collisions happen.
We know for a fact that cosmic collisions occur. We had repeated graphic examples of this in July 1994, when the comet Shoemaker-Levy 9 broke into dozens of pieces and slammed repeatedly into Jupiter, releasing more energy than could humankind's entire nuclear arsenal. Had the comet hit Earth instead of Jupiter, it would have been a catastrophe of, well, biblical proportions. Humanity, along with 95% of the land animals on Earth, would almost certainly have been wiped out.
And even this collision is small potatoes. In the early past, when the disk was forming into planets, gravitational interactions would have been common. Two planets forming too closely together would affect each others' orbits, and the smaller one might actually get flung into a wildly different orbit. This orbit could have sent it on a collision course with another planet. An off-center, grazing collision could physically tilt a planet, changing the axis of rotation, in much the same way that poking a spinning top off-center causes the axis to wobble.
In the case of Uranus, a large collision is what most likely knocked it on its side. For poor Venus, whatever collided with it knocked it almost completely heels-over-head. To us it looks like Venus is upside-down and spinning backwards.
Ironically, this catastrophic view of planetary dynamics is more biblical than classically scientific. For many years, scientists avoided using catastrophes to explain events, since they were hard to reproduce, difficult to analyze statistically, and smacked of biblical events. In the end, though, science learned that catastrophes do happen, which is its strength. When presented with evidence contrary to the theory, science learns and grows.
All 63 moons in the solar system should orbit their planets in the same sense, but at least six have backward orbits. Furthermore, Jupiter, Saturn, and Neptune have moons orbiting in both directions.
This one is really easy to explain. Some of the moons of the planets formed at the same time as the planets and orbit their parent bodies in the "correct" sense, that is, in the same direction that the planet spins and orbits the Sun. However, it's possible, although generally not easy, for a planet to capture moon-sized objects. If the conditions are just right, it's not only possible but rather common that such a captured moon would orbit the planet in the opposite direction. Jupiter and Saturn both have moons that orbit backwards, or retrograde. All of these moons orbit at large distances from their planet, as is expected in a capture event as well.
Again, using this as a creationist argument is disingenuous on their part. Retrograde moons have been known about and explained for many decades.
The sun turns the slowest, the planets the next slowest, and the moons the fastest. But according to evolutionary theories, the opposite should be true. The sun should have 700 times more angular momentum than all the planets combined. Instead, the planets have 50 times more angular momentum than the sun. The sun has 99.9% of the total mass of the solar system, but 99% of the total angular momentum is concentrated in the larger planets.
According to the cloud-collapse theory, the Sun should indeed be spinning faster than any solar-system body. When a figure skater draws in her arms during a spin, she spins faster and faster. The fancy name for this is conservation of angular momentum, which just means that a big thing will spin faster if it shrinks.
This happened to our proto-solar-system cloud when it collapsed, too. It spun faster as it collapsed. Since the Sun was at the center of the cloud, it should have sped up the most. But, apparently contrary to this theory, the Sun currently spins only once a month. This is the key to the last of these creationist arguments about the solar system.
Before it formed, the solar system was basically a giant cloud of dust and gas, roughly spherical in shape. As it collapsed, it began to spin, and this caused it to flatten out. The planets formed after the collapse, which is why they all orbit the Sun in roughly the same plane.
The creationists, as usual, are oversimplifying the problem. The universe is many things, but one thing it isn't is simple. However, it usually makes sense, so if you see something that doesn't make sense, look around. The solution may be blowing right past you.
In this case, that's literally true. The Sun is constantly blowing a wind. This solar wind flows from the Sun's surface at a rate of about a thousand tons of gas per second. But the Sun is pretty big and has mass to lose. It can easily shed a few billion tons a year and hardly notice the difference.
The solar wind is made up of charged particles-electrons and protons. Left to themselves, they would blow straight out from the Sun into infinity. But they are not left to themselves. The Sun itself has a pretty hefty magnetic field, and this field rotates with the Sun. As it spins, the sun drags the particles along with it. This in turn acts like a brake on the Sun's rotation, slowing its spin.
This isn't too difficult to understand. Imagine standing in your front yard with a big trash bag in your hands. Open it up, hold it out to your side, and start spinning. The bag acts like a parachute, scooping up air and slowing you down. The exact same thing is happening to the Sun. The magnetic field is like a huge parachute, scooping up particles. The "air"-the particles in the solar windis very tenuous, and the Sun is large and heavy, but this drag (despite what the creationists might think) has had a long time in which to work. Over 4.5 billion years it has quite possibly slowed the Sun substantially to its current rather stately monthly rotation. While this theory has not been conclusively proven, it remains a leading contender to explain the angular momentum problem. There are other theories as well, such as the idea that the Sun lost most of its angular momentum very early on, as a protostar. It may have shed a lot of its mass through long episodes of a sort of supersolar wind. While astronomers are not totally sure which of these ideas is the correct solution, the fact remains that there are plenty of ideas, and they use good, solid physics.
There are not enough old supernovas to justify an old galaxy.
Of all the creationist arguments involving astronomy, this one is my favorite. Basically, it goes like this: some stars, at the ends of their lives, explode. This doesn't happen terribly often, and only stars far more massive than the Sun ever explode in this way. When they do, it's called a supernova.
The explosion is so bright that it can outshine entire galaxies and be seen clear across the universe, and it is so violent that the outer layers of the star are flung outward at an appreciable fraction of the speed of light. This rapidly expanding cloud of debris, called the ejecta, or sometimes the remnant, can glow for many tens or even hundreds of thousands of years.
You can see where this is going. Creationists take exception to the idea of old supernova remnants, of course, since according to them, none can be older than 6,000 years. As a matter of fact, a relatively new and bold claim by the creationists is that there is no supernova remnant older than at most 10,000 years. This argument has been used by noted creationist Keith Davies, and is also used by the Institute for Creation Research itself. They list it prominently at their web site, and it carries a lot of their weight. If it's wrong, then so are they.
It's wrong. Davies goes through a tremendous number of observations and calculations to show that, according to mainstream science, there should be lots of very old supernova remnants in the sky, yet none is to be found. He uses lots of math and fancy graphics to prove his point.
The funny thing is that he is missing the forest for the trees, so to speak. I could go into just as much detail showing why there really are supernova remnants older than 6,000 years, and some that are actually hundreds of thousands of years old. But I don't need to. Even if we grant that there are no remnants older than 6,000 years, it doesn't matter. Davies's whole line of attack is wrong for a very simple reason: Supernova remnants were not created at the moment the universe began.
According to the creationists, this (supposed) lack of old remnants indicates the universe is young. But remember, the remnants form when a star goes supernova at the end of its life. Stars live longer than 6,000 years-far, far longer. The absolute minimum age at which a star can blow up is roughly a million years old, so no matter how you slice it, the universe must be at least that old for us to see supernova remnants at all. So, even if we grant that the oldest remnant is 6,000 years old, the universe must be 1,006,000 years old at least for us to see it.
That's why this is one of my favorite creationist arguments. In this case, they are using a sort of sleight-of-hand, a magician's trick to distract you by using complex mathematics, when in fact the argument rests on a fatally flawed premise. You don't need to do any fancy math at all; a little logic destroys their argument.
Incidentally, as an indication of Davies's misunderstanding of all this, he has an image of a star on his web page that he has labeled as a supernova. It isn't. It's really just a plain old star that's been overexposed, a fact that is easy to verify by simply opening nearly any astronomy textbook. Ironically, the very first thing you see on his (very long) web page shows that he doesn't understand what a supernova is at all.
The creationists' attack on science is a serious issue. It goes far beyond bad astronomy. Indeed, astronomy is only the most recent of repeated attacks on mainstream science that they have initiated. Their feelings about biology are well-known in the United States. In 1999 the Kansas School Board discouraged the teaching of biological evolution in middle and high schools by removing all statewide standardized testing about it. This was accomplished because the school board had been packed with creationists in the previous election. Before the election, the creationist candidates had downplayed their religious ties. They also relied on the voters being too apathetic to research their candidates' histories. That gamble paid off, and the result was a creationist school board, a nationwide controversy, and a terrible embarrassment for the Kansas-and American-educational system.
Perhaps more frightening were the reactions of other politicians to this. Several contenders in the 2000 presidential election were sympathetic to the board's decision, without any understanding of the lack of scientific reasoning behind it.
One of my favorite phrases from the Bible is, "The truth shall set you free." Ironically, creationists don't want you to know the truth. They want you to know what they say is the truth, and sci ence isn't like that. Scientists understand that the universe is trying to show us the truth, and all we need to do is figure it out. It's clear from this short selection of astronomical topics that when it comes to science and critical thinking, creationists are selling a bill of goods. My advice: don't buy it.
A happy addendum: upon the next election, the public having learned of their true agenda, three of the creationist Kansas School Board members were voted out of office. One spent an unprecedented amount of money in advertising and was ousted, anyway. The new board quickly reinstated teaching evolution in the curriculum. Like science, sometimes even the political process is selfcorrecting.