Superman and the Physics of Collapsing Buildings

I saw the new Superman movie this weekend, and I liked it. But it wasn't perfect, and the thing that bothered me the most was the bad physics. I'm not talking about Superman being able to fly or the Kryptonian terraforming machine being able to increase Earth's mass. That kind of thing is expected in a superhero movie. I'm talking about more everyday physics. The most egregious example is skyscrapers falling over.

It happens multiple times in the movie. Superman throws a bad guy (or a bad guy throws Superman) through a skyscraper, part of the building is damaged, it tips and falls over like a tree. You might be wondering what's wrong with that. After all, trees fall down like that. If you build a tower out of Legos and knock it down, it falls down like that. But large buildings don't fall down like trees or Legos. They don't fall over sideways, they simply fall straight down.

So, why do large building fall down? Because gravity pulls them down. It does not pull sideways, so it doesn't tip sideways. But then why do Legos and trees fall sideways? Because there are other forces at work, namely the internal forces holding them together and in the same shape. Gravity is pulling down, but the internal forces prevent the top from simply collapsing into the bottom, so it falls sideways.

Here's a force diagram of a brick in a Lego tower tipping over. Gravity is pulling down. Normal force is pushing at the same angle the building is tipping. The total force is in blue. The vertical components mostly cancel, leaving the total force going mostly sideways.

But why don't large buildings do the same? Don't they have internal forces too? Well, yes, but they don't scale up. As the building gets bigger, it gets heavier, and gravity pulls more strongly. The internal forces of a large building will be stronger than those of a Lego building because it's made with steel rather than plastic, but it will be weaker relative to the force of gravity. The normal force will still be there, causing it to tip just a little bit, but gravity will dominate, so it will fall almost straight down. The top will simply collapse into the bottom, rather than being pushed to the side.

So why does this matter? It's just a movie, right? That's true, but understanding physics and how forces scale can be important. For example, there was a very well known case where some tall buildings fell down unexpectedly. As physics predicts, the buildings fell mostly straight down. (But not entirely. A lot of nearby buildings were hit by debris.) But a lot of people didn't understand the physics, and thought that the fact that the buildings fell down instead of over meant the buildings weren't brought down by airplanes, but rather by controlled demolition, and thus a conspiracy theory was born.

An Abortion Hypothetical

People opposed to the right to get an abortion like to make the argument that a fetus is alive, has a heartbeat, can feel pain, etc. It's obvious that these features are not sufficient to make the case. After all, cows have all those things, but the same people who complain about abortions don't usually have problems with eating meat.

But there's a related feature (well, more of a complex conglomeration of features) that isn't so obviously irrelevant. Is a fetus a person? That's a more reasonable question. But I still don't think it's relevant. Even if a fetus were undeniably a person, I'd still be in favor of the right to get an abortion. I'll illustrate with a hypothetical.

Suppose one winter's day, you accidentally leave your door unlocked. When you get home, you find that a homeless man has taken up residence. He doesn't pose any direct threat to you. He just takes up space, eats your food, and is generally inconvenient.

So, you decide to kick him out. "But", the homeless man protests, "It's freezing out there, and I have nowhere else to go! If you kick me out, I'll surely die!"

Is it morally prohibited to kick him out? Should you be required to provide him with food and shelter?

Now obviously, this hypothetical has a lot of differences from abortion. Here are the two I find most important.

One, homeless man is most definitely a person. A fetus may have a heartbeat, but this guy can talk. In the case of abortion, the status of the fetus is, at best, ambiguous.

Two, the homeless man is only taking shelter in your house, not your body. If you're allowed to decide who may or may not be in your property, surely you should be allowed to decide who may or may not be in your body.

And that's the important point of the abortion debate. It's not whether or not the fetus is a person. It's about whether women have the right to control their own bodies.

Jesus

On this day of Easter, let us not forget this important fact: Jesus did not exist.

Now, don't get me wrong. It's entirely possible, perhaps even probable, that there was a guy named Yeshua who came from Nazareth and preached in Jerusalem and was crucified for his beliefs.

But that's not the person that Christians are talking about when they talk about Jesus. They're talking about the son of God, born of a virgin, who performed miracles and rose from the dead. That Jesus never existed. And that Jesus is not the same person as Yeshua. If he is, then Santa Claus lived in Turkey in 300 AD.

And we know next to nothing about the "real" Jesus. The only writings we have that talk about Jesus and were written anywhere close to when he actually lived were written by Christians, and were talking about the miraculous version.

EDIT:
And it's entirely possible the "real" Jesus didn't exist either.

Moral Intuition

We usually judge moral theories with our intuition. We see what a moral theory says about a hypothetical scenario and see if that agrees with our intuition. People arguing for a particular moral theory frequently give examples of situations in which that moral theory gives an answer that most people's intuitions agree with. People arguing against a particular moral theory frequently give examples of situations in which that moral theory gives an answer the most people's intuitions disagree with.

But a lot of times the examples used are very unlikely situations. That's not a problem for the moral theory. A good moral theory should work in any situation, likely or unlikely. But it is a problem for our intuition.

Intuition is only useful in circumstances it evolved in.

Consider physics. Humans have pretty good intuition with regards to running, jumping, throwing and other things we've been doing for millions of years. But outside our relatively limited experience, our intuition is virtually useless. There's nothing intuitive about general relativity or quantum mechanics.

Which is why I don't think hypothetical problems like the Trolley Problem are useful in determining what makes a good moral theory (though they can be useful in helping us examine our intuitions). Because such hypothetical scenarios rarely reflect our normal experience, so our intuitions don't necessarily apply.

So then, the question is, if we can't trust our moral intuition, then how should we judge a moral theory?

Would Gay Marriage Lead to Polygamy?

An argument that opponents of gay marriage make is that legalizing gay marriage will inevitably lead to legalizing polygamy, which would be a bad thing, therefore gay marriage shouldn't be legalized.

As a syllogism, it's not invalid. If the premises are true, the conclusion is too. If gay marriage actually did lead inevitably to polygamy and polygamy actually were a bad thing then gay marriage is a bad thing. But neither premise is true, so the conclusion doesn't follow.

I don't think there's anything inherently wrong with polygamy. Past implementations of it have been sexist and bad, but then again, past implementations of regular marriage have also been sexist and bad.

And gay marriage won't lead inevitably to polygamy because they're two separate issues - and polygamy is significantly more complicated. To change straight-only marriage to include gay marriage, all you have to do is replace every instance of the word "man" and "woman" with "person" and replace every instance "husband" and "wife" with "spouse". It's not like the husband gets certain privileges the wife doesn't, at least, not anymore.

But to generalize marriage to more than two people takes more work then simply replacing "two" with "two or more", because a lot of the ways marriage currently works assumes that there are only two people involved. For example, when one spouse has a medical problem and is incapable of making a decision about what to do, the other gets to decide. How would that work if there's more than one other? What if they disagree? Also, is marriage a transitive property? That is, if A is married to B and B is married to C, does that mean that A is married to C? These are questions that never arise when marriage is restricted to pairs.

I don't have any answers to those questions, but they'll need to be answered to legalize polygamy. And legalizing gay marriage doesn't get us any closer to answering them, which is why it won't inevitably lead to polygamy.

Beware Superstimulus

All animals have evolved instincts and reactions to stimuli they ordinarily encounter. For example, birds protect things that look like eggs, because ordinarily if something looks like an egg, it is an egg. And they'll protect larger eggs rather than smaller eggs, because more resources go into creating a larger egg.

But in a scientist's lab, something that looks like an egg might not actually be an egg. And in such circumstances, birds will protect large non-eggs more than small eggs. They respond to the stimulus even when it no longer indicates what it ordinarily indicates, and the stronger the stimulus, the stronger the response.

We are just as susceptible to this as other animals. In our ancestral environment, sugar and fat were hard to come by, so when it did come by, you wanted to eat as much as you could while it lasted. So sugar and fat taste good, and they keep tasting good even when they are no longer in short supply.

Superstimuli are a large cause of today's obesity epidemic. Ice cream and cheeseburgers have more concentrated sugar and fat than anything a hunter-gatherer could get, so they trigger a stronger response.

Superstimuli apply to more than just food. Models are made-up and airbrushed to look more perfect than any real person ever could. Our modern society is inundated with superstimuli. Movies, television, computer games, the internet, porn. These all provide stronger stimuli than you could ever get otherwise. And when the stimulus becomes disconnected from the benefit it provides, the response does as well.

AlDraw on Android

I've mentioned my program AlDraw before. It's the one that lets you make cool geometrical constructions like you can see here.

Well, now I've released it as an Android app. If you have a device with Android 3.0 or higher, check it out! https://play.google.com/store/apps/details?id=strinka.aldrawandroid