In 2014, popular science communicator Bill Nye “debated” creationist Ken Ham in a live webcast on YouTube. The event went pretty much as expected; Nye presented levelheaded evidence that science works, that evolution is real, and the Universe is very old, while Ham used bad logic, cherry-picking, and blatant twisting of scientific claims.

At the time (and still today) I think Nye made the right decision to participate in the event. Ham runs the Answers in Genesis ministry, and also the Creation Museum in Kentucky, and is well-known for his outrageous statements. It might seem silly to elevate the debate by paying any attention at all to Ham, but that ignores the fact that polls consistently show that half of the American population believes in some form of creationism.

We ignore this at our own peril.

Debating creationists is slippery. When your opponent doesn’t have to adhere to facts or logic, it’s tricky to find traction. My friend Zach Weinersmith once wrote that it’s not that most creationists are anti-evolution, it’s that they’re anti-some distorted version of it told to them by their pastors.

He’s completely correct. That became even clearer to me when, shortly after the debate, BuzzFeed posted an article called “22 Messages From Creationists to People Who Believe in Evolution”. It was clear from the questions asked that the creationists involved had no idea about how evolution—even science itself—worked. The questions were universally based on false premises, a distortion of the science that made it actually pretty easy to answer those supposedly “gotcha” queries.

So I did answer them, in a post titled “Answers for Creationists.” I politely, but firmly, answered the questions posed, with links to expert sources if anyone wanted to dig a little deeper. It became one of my most popular articles of all time.

But as Zach pointed out, while these questions have been answered countless times, they still get asked. Why? The answer is obvious: Because the people asking those questions are still getting their information from people like Ken Ham who refuse to listen to anything science has to say and who still propagate falsehoods.

And I know this for a fact. That’s because Ham took to Twitter recently, posting a series of tweets that are not just wrong, but completely wrong, again demonstrating not just a misunderstanding of the topic, but a deep—I daresay fundamental—lack of understanding of even the most basic facts about the science he’s trying to deny.

It’s enlightening to look over what he said, because, again, a lot of people listen to him. And, like my previous post about answering creationists’ questions, I address this not to Ham, but to those who might listen to him: Perhaps you’ve heard these claims, and wondered about them. Here’s what science has to say about them.

First up: a bad Moon rising.

The recession of the moon is evidence confirming the moon cannot be 4+ billion years old--it would have touched the earth way before then — Ken Ham (@aigkenham) May 3, 2016

Like most such claims, it’s based on a kernel of truth: The Moon is in fact receding from the Earth, by a rate of about 4 centimeters per year. That’s roughly at the same rate your fingernails grow. The motion is due to the way Earth’s gravity affects the Moon, through the tidal force.

This means that, in the past, the Moon was closer to the Earth. And this is where—if you believe Ham—you run into a problem. The rate at which the Moon recedes depends very strongly on its distance from the Earth. In the past, when it was closer, it would have receded even more quickly.

According to Ham’s thinking, that means the Moon must be younger than science would say, only a billion or so years old at the most. A relatively simple calculation shows that, given the faster recession in the past, the Moon would have been touching the Earth about a billion years ago.

But this is incorrect. The real problem here is a common one with claims like this: taking a trend and simply running it backward or forward as if nothing ever changes.

In this case, there are other factors that affect the Moon’s recession rate, and Ham ignores them. For example, the shape of the continents and shorelines on Earth has a large effect as well (because the tidal interaction depends strongly on the way the water and seabed on Earth interact). It turns out that we have an anomalously high rate of recession today; many studies show that in the past the rate was actually slower.

Yes, initially, right after the Moon formed, it receded very rapidly indeed. But as it receded, other factors came into play. The numbers as we see them now easily allow a 4.5 billion year old Moon, just as scientific theory predicts.

Moving on, a little closer to home:

Earth's magnetic field is decaying--the earth couldn't be millions of years old-life couldn't have existed with a stronger field in the past — Ken Ham (@aigkenham) May 3, 2016

Again, a nugget of truth: The Earth’s magnetic field is changing. It does this all the time; it’s generated deep inside the Earth by our very hot iron core. The inner core is solid, but the outer core is liquid. The heat from the inner core causes the molten iron to rise, cool, and sink again. The iron is so hot it’s ionized (electrons are stripped from their atoms), and when an ionized fluid moves, it can generate a magnetic field. Changes in the liquid outer core change the Earth’s magnetic field, which we can see. For example, the magnetic poles of the Earth wander and the field strength changes.

If the field is decreasing now, it must have been stronger in the past. Ham’s mistake here, again, is assuming that increase in the past just keeps on going up and up. But we know that’s not true; there’s copious evidence the field cycles—waxing and waning in strength, and even reversing polarity. And even if Ham were right, he simply asserts life couldn’t exist in a stronger magnetic field but offers no reason why that might be the case.

Next, Ham ventures out into the Universe:

Spiral galaxies rotate differentially--inner region faster than outer--if universe billions of yrs old there'd be no spiral galaxies — Ken Ham (@aigkenham) May 3, 2016

When you look at the spiral of cream in your coffee cup after you stir it, the inner part does spin faster than the outer parts. But galaxies aren’t like that. The arms aren’t coherent structures that spin like cream in your mug o’ java; they’re more like traveling traffic jams.

Pity Ham hasn’t seen my episode of Crash Course Astronomy where I talk about exactly this:

By the way, scientists have known for nearly a century that spiral arms don’t and shouldn’t wind themselves up.

Now let’s see what Ham has to say about the entire Universe:

Christians who add Big Bang belief into the Bible are adding man's pagan religion to try to explain the universe without God into God's Word — Ken Ham (@aigkenham) May 3, 2016

This is a little confused. First of all, the use of the word pagan is odd. That refers to a religion that’s not one of the world’s main religions. But the Big Bang, and science at large, is not a religion. It’s not even faith-based.

But then Ham compounds his mistake:

The Big Bang is a belief (it's not a theory)--it's part of man's failed religion to try to explain the universe by natural processes — Ken Ham (@aigkenham) May 3, 2016

The Big Bang is not a belief or a religion. It’s actually a model of how the Universe began, or more accurately what happened in the teeniest tiniest fraction of a second after the Universe began. And it’s supported by a vast amount of observational and theoretical evidence. No faith is needed.

And I just happen to have covered that in Crash Course Astronomy as well!

And then we get to this statement by Ham:

The Big Bang belief (part of the evolutionary religion) conflicts with the Bible's clearing teaching the earth was created before the sun — Ken Ham (@aigkenham) May 3, 2016

(I assume he meant “clearly,” not “clearing.”)

This one is odd as well. All he’s really saying is that science contradicts a literal interpretation of the Bible. But we’ve known for a long time. If that’s his complaint, he better have a seat. Even if you just stick to Genesis, the contradictions make for a long, long list.

In this case, the Bible says the Earth was created before the Sun. Science says they actually formed around the same time, 4.56 billion years ago. The Sun may have started nuclear fusion in its core, becoming an actual star, a few million years before the Earth grew to become a planet … but it hardly matters, since Ham isn’t really trying to refute any actual scientific claim here.

Also, he is very confused about what the Big Bang model says. That’s all about how the Universe itself got its start nearly 14 billion years ago. But the Sun has nothing to do with that; it was born nearly 10 billion years later. I see this confusion by creationists quite a bit; I strongly suspect it has to do more with trying to scare believers using the term “Big Bang” than understanding what the model is actually telling us.

I could go on and on; digging back through Ham’s tweets provides endless material for this exercise. But the point is clear: Ham’s mistake here is not sticking with his religion, but instead trying to disprove science using science. Given his bias, and his basic misunderstanding of what science is and how it works, he’s doomed to fail.

I’ve said this before, but it bears repeating: I think that people have the right to believe what they want. But when that belief clearly contradicts what we know to be true due to our observations of the Universe, and someone is vocal about it, well, we’re going to have a problem.

Ham clearly feels that his religion is threatened by science. That’s true, because it is. But not all religion feels that way; in the same year Ham stood up and said all those wrong things to Bill Nye, Pope Francis stood up and declared that the Big Bang and evolution are no threat to Catholic beliefs.

Catholicism is followed by more than 1 billion people on our planet. If their leader feels science is no threat to them, then maybe there’s hope that other, more intractable religions will follow suit.

Clearly, though, Ham won’t. The fact that he’s repeating provably false statements literally decades after they’ve been shown to be wrong, and publicly displaying his profound lack of understanding of science, shows that all he will do is dig in further.

We have all the evidence we need for that.

Post script: The claims Ham made, and my rebuttals, are a drop in the bucket compared with what’s out there. If you want to read more, then I suggest checking the following sites: