The definition of "black"

Sometimes people get so technical in creating definitions that they end up defining or categorizing things in a way that flatly contradicts the colloquial definitions of those things. I think that's lame.

One example is the question of whether black is a color. Some people say that it's not because it's the "absence of color", or it's a "shade", which can be used to modify a "color". 

But, come on. "Color" is a way to describe what frequencies of light come from an object to our eyes, and which of the light receptors in our retinas react to those frequencies. We experience colors as contrasts to other colors - just try and describe how a color looks in any other way. In that sense, black is definitely a color. It's one of the ways our eyes perceive light bouncing off of things. If someone is wearing a black shirt, and you ask them what color it is, they don't go "Oh my gosh there IS no color!" They also don't try to figure out which primary or secondary color is being reflected the most and then say something like "I think it's a profoundly dark green." They say it's black. And even you developed some ultra-Vantablack shirt and there were no light coming off of it at all, zero is a valid value that something can have. But then again, there's never really zero light.

And that brings me to another point. Some people say that nothing is really black, because black means no light and everything reflects a little light (except a black hole I guess). But dude, that is NOT the definition of black. If it were, it would be totally useless. That's like saying nothing is cold because nothing has a temperature of absolute zero. There are plenty of things that we all look at and say are black. That's the definition of black. It's all relative. All colors are relative. There's no use defining a common word in such a way that it can't actually be applied to anything.

Edit: The same principle applies to magenta. If you think the definitionn of "color" is "light frequency", then magenta isn't a color either, because that's just how our brain interprets blue + red. And for that matter, brown isn't in the rainbow either. So either none of these things are colors, or "color" refers to how our brain processes light, and not just the frequency of light we see.

Flat Earth & the Alt Right

I had a bit of an epiphany today. It involves to seemingly-unrelated topics - one pretty trivial and the other very important. But they share something important in common. I'll start with the trivial one.

Debunking "Flat Earth"

A few days ago, I made the mistake of reading the comments on a Facebook post about some astronomy thing and was painfully reminded that there are a bunch of people who are convinced that the world is flat, and that all the evidence to the contrary is either forged or misunderstood. For some reason, it really, really bugs me to think that there are people who believe this. I find myself wishing that I could sit down with these people and have an honest conversation; I felt like if I could just ask them one or two questions, I could convince them to change their ways.

This begs the question: if you only had their attention for one question, which would you ask? It can't be too complex or rely too much on math, because if you have to rely on something that abstract then you've already lost the argument. I had a progression of questions that came to mind (along with some of the responses I might get):

1. Why hasn't anybody just taken a picture of the edge? That should settle the matter pretty easily. (I guess they believe the South "Pole" is the edge, and it's dangerous to get there, and your navigation gets messed up, so you're not where you think you are.)
2. If you can't get to the edge, then why not just do a trip around the edge of Antarctica, and measure the distance/time? With the globe model, the trip should be the same as a trip at a high northern latitude. But with the flat model, the trip should be much longer than it would be even at the equator.
3. My wife brought up the question of seasons - that doesn't really make sense in a flat world. (I guess a lot of people don't understand the seasons anyway.)
4. Similarly, what about the sun rising in the east? If I see the sun rise on the eastern horizon, shouldn't everyone? (I wondered if maybe they thought that horizon is just as far as you can see, so maybe they'd think that the sun on the horizon just means the sun is really far away but in the sky?)
5. Even simpler: If it's noon for me, the sun is high above. Shouldn't it be high above for everybody? Why is there no sun in the sky at all for some people?

I think question #5 should do it. The fact that some people see the sun to the east, others to the west, some straight up, and others not at all - at the same time - has to mean that the world isn't flat. And it's super simple - it relies only on a phenomenon that we experience every single day.

So, why do I care so much about people not believing this? Hold that thought for just a moment.

Debunking White Supremacy

There are people in the country right now who are convinced that white people are in danger. I'll discuss why this is wrong later, but for just a moment, let's try (I know it hurts) to understand their claims. They see all the good stuff in American history and American culture, and guess what? Most if it involves white people. These people, like all people, have problems. And they look around and see efforts to lift minorities out of what seems like very similar problems. Scholarships. Quotas in schools. Diversity efforts in companies. From these people's perspectives, these efforts can't help but displace white people and supplant their culture.

To be very clear, that's all a distortion of the truth. It's too big a topic to discuss fully, but let me give a quick example of why. Let's say you're a white guy who's applying for a job. There are ten positions open, and twenty people applying - ten white and ten black, all of them qualified. The employer is a white supremacist. Guess what? You have a 100% chance of being hired!

Now change the scenario - let's say that the employer isn't racist, and laws prohibit hiring based on race. Now your chances of getting the job have dropped to 50%! From a purely self-centered, unprincipled point of view, the change in policy has hurt you. It has taken a chance that was once yours and given it away. I guess that's why the "alt right" is worried. But of course we can see that the extra chance you had originally was unfair, and the new system is actually better. It's just not more convenient for you. And if you're a moral person, that distinction matters.

And one more thing: Since before this country was founded, you've had white people who knew that racism was hypocrisy in a nation that believed in freedom. You have also had people who were afraid that if you granted freedom to minorities (particularly black people), then they'd use that freedom to retaliate. And guess what? Those people have been wrong every time. The slaves didn't try to take over the south. When black people could vote, they didn't try to eradicate white people. Sure, you've got the occasional evil person who has advocated violence, but the fact is that white people at large have never been in danger from the people who have managed to get free of the historical oppression that has afflicted them.

Epiphany

The second point has been on my mind in the past few days due to the Charlottesville thing. And today as I was thinking about the flat earth bit, I realized why it bugs me. It's because of the mentality that leads to it - and that it's exactly the same mentality that leads to a belief in white supremacy.

Believing that the world is flat involves limiting your point of view to your own experience, ignoring the multitude of experiences that show that the world is more complex and more interconnected than you can tell from any single point. If you open yourself up to what the world is like to someone on the other side of it, you have to realize that the flat earth model is inadequate. And the same is true of white supremacy. Sure, you can find someone with darker skin who has life a little easier than you. But if you listen to just a few of the stories of this country, you'll see the obvious - that there's this big, ugly stain on American history made of racism. We have come a long way toward removing it, but there are still people suffering from it. A lot of people. We can disagree on the best way to fix it. But pretending that white people are in danger from our dark-skinned neighbors is just as wrong - and even more infuriating - than believing the world is flat.

And that leads to an important distinction: While people's belief in a flat earth doesn't really hurt anyone, the belief that white people are superior and threatened is extremely damaging. It's making that big ugly stain grow even as we're trying to wash it out. People are literally dying because of it.

I'm really not sure what the best way to fix the problem is, especially since I'm pretty much preaching to the choir as I write this. But I hope that someday I get to talk to a white supremacist. Not to yell at them or tell them how embarrassed I am to have them in my country (although that might be the gut reaction), but to sincerely talk and maybe ask them one question in an effort to force them to see the world in a new, broader way. To change their mind. I wonder what question it would take to get them to do it.

Non-stupid dragon rider travel algorithm

I'm not a fan of Eragon - see the Books page for details. One (not the largest) of my complaints involves a moment where a couple of people (or maybe three) have a horse to carry their baggage, and of course they're traveling with a dragon. Since the dragon can't carry everyone, they decide to walk from one town to a distant one.

Stupid.

Of course the most straightforward thing would be for the dragon to carry one person (or however much she can carry) in one trip, then return for the next load, and so forth. Presumably a dragon could make several trips between towns in less time than it could take a person to walk. But for some reason I found myself thinking a little harder about this - specifically, how to optimize things for the shortest possible trip.

I started with a few constraints, which may or may not be valid in the book, but that's fine. For the sake of simplicity, let's say that on a given trip the dragon can carry one human, or all of the luggage, or the horse. (Granted, the horse would weigh more than two humans, so the dragon should be able to carry them both, but maybe the humans don't feel comfortable being dangled by just one set of claws or something. Or maybe the dragon can't carry the horse, but that makes this problem less interesting.) Another possible constraint is to ensure that you don't leave the luggage or the horse unattended. If it's okay to leave the luggage alone, and if there are two humans, then we have a fairly simple way of shortening the time even more:

1. The dragon carries the luggage to the end point. At the same time, one human starts off on the horse while the other starts walking.
2. When the dragon drops off the luggage, it returns to pick up the walking human. 
3. The dragon drops the human off with the luggage and returns for the horse. (By this time, the horse and remaining human have covered a lot of distance, so the dragon doesn't have nearly as far to go.)
4. The dragon drops off the horse and goes back for the final human.

We can optimize things a little further, because at step 3, the dragon doesn't have to carry the human all the way to the luggage - just close enough that the human can reach it before the final trip is over.
It might be possible to advance things even further,  if we can assume that extra trips for the dragon are offset by less time spent with a human on foot. At step 3, the dragon drops the first human off at an even farther distance from the end. Then at step 4, the dragon carries the horse from the second person to the first, then goes back for the second person. This way, more time is spent with the slowest traveler on horseback rather than walking. Like I said, this might (depending on relative speeds and distances) offset the need for some extra partial trips for the dragon.

Things get even more complex if we add the constraint that the luggage must always be in the company of a human or dragon. (Maybe there are lots of thieves around.) In this case, the luggage becomes the limiting factor. Again, assuming two humans:

1. The dragon takes human #1 far ahead, but not quite to the goal. The human starts walking. At the same time, the other human begins walking the the laden horse.
2. The dragon takes the luggage to human #1's position. That human must now stop. But human #2 can now ride the horse and move faster.
3. The dragon takes the horse to human #1, who can now move. Human #2 continues on foot.
4. The dragon takes human #2 very near the end point
5. The dragon takes the luggage to the end point, arriving at the same time as human #2. Human #1 can now ride.
6. The dragon takes the horse to the end point. (Unfortunately, the horse's extra speed is now wasted.)
7. The dragon takes human #1 to the end point.

Again, we might be able to optimize this by having the drop-off point for the luggage at step 5 some distance from the end point. That way human #2 can continue with the horse and luggage while the dragon goes back for human #1. But this would also mean that the human is stationary in-between receiving the luggage and receiving the horse, which might offset this. Of course, adding a third person would really free things up and allow the horse to continue running right up until the end, similar to the first scenario. (Although of course that would also add additional trips.)

You'll notice that I've left the math out of this completely, which is why it's not possible to come up with a definitive optimal solution. I guess this would be a good interview question if math were relevant. Maybe someday I'll write a program to simulate the situation - it would be pretty cool to have little icons representing the different elements and let you tell the dragon which thing to pick up and when to drop off. In the meantime, though, please don't make stupid choices like walking somewhere you're in a hurry to get to when there's fast and free transportation available.

Bad commentary on space

As a public service, I want to point out some flawed space-related comments I’ve heard recently.

The first was from an Air Force ad. Now, I’m all for the Air Force. But they said they were “pioneering new paths to space.” Really? I’m pretty sure there’s just the one path: up through the atmosphere. Space travel has had lots of obstacles, but a lack of paths hasn’t been one of them.

The other was from NASA. The article below contains the following quote: “We are closer to sending humans to Mars than at any point in NASA’s history.” Well of course we’re closer. Any point in the future only gets closer, right?

http://news.yahoo.com/nasa-closer-sending-humans-mars-163300699.html

There. I feel better now.

Weird Butterfly Antics

I can’t say that I spend a lot of time thinking about butterflies. They’re fairly non-gross insects (as adults) that have a mysterious flight mechanism, and sometimes they have cool colors. That’s about it. But today I was on a field trip with my daughter, and we went into a butterfly house, and the following weird things happened:

1. A large, five-or-six-inch butterfly landed on my shirt and just hung out there for a couple of minutes.
2. After it left, a similar one (or maybe the same one) landed right on top of my head.
3. On the screen wall, there was another one of these large butterflies, with a hitchhiker. Or rather a hitch-sitter. A smaller butterfly was actually sitting there on the larger one’s wing.

This phone camera isn’t great, and the angle makes it hard to see the big butterfly, but it’s that long, light-brown line in the center:

The Chicken or the Egg?

I would like to announce that I have solved the chicken-or-the-egg problem:

An egg is a chicken.

Think about it. A fertilized egg is a single cell with complete chicken DNA. When a chick breaks out of its egg, it’s really just shedding a layer of itself, the way scorpions molt from their old skin.

(Of course, this still begs the question of whether the first chicken appeared as an egg or an adult, or something in-between. But putting it that way is not nearly as compelling.)

Equal Opportunity Dinosaur Status

Paleontologists are picky about what they call a “dinosaur.” To an extent, I get it. I don’t really care if Dimetrodon’s hips pointed out or down, but if it was cold-blooded, then it’s a different thing. Fine. But excluding pterosaurs and swimming non-fish, egg-laying vertebrates seems unreasonable. From the old-style books I read back in the day, I gathered that at least one reason for the distinction was that they figured that those things would have to be warm-blooded, while the consensus was that dinosaurs were cold-blooded. You know, reptiles. But even then I was skeptical of that. I mean, brachiosaurus having to stay in a lake just to keep themselves up?

So now that we know that dinosaurs were warm blooded, and keeping in mind that we’re okay saying that bats and whales are mammals, I think it’s time to include flying and swimming creatures in the definition of “dinosaurs.” It’s fair, it’s intuitive, and it’s probably how most people use the word anyway.

Let’s all agree to just do the right thing.

Military Feng Shui

I have this really, really great idea. As I understand it, Feng Shui is about positioning objects to channel chi in a way that is beneficial to the people it flows around. (I know the official spelling is “qi”, but I’m a fan of phonetic spelling when possible.) So what if we tried using it for purposes other than home furnishing? Imagine lining up your tanks and cannons and soldiers (and couches, if you want) in such a way that all the chi in the area flows around them and gives them a tactical advantage. Or even in a way that forces a bunch of chi forward in a concentrated beam – a chi laser! You could also trick your enemies into maneuvering into a formation that seems to give them a tactical advantage, but then all of a sudden all their equipment shuts down or falls apart. You cannot tell me that this is not a fantastic idea. (Hopefully I am not spoiling any national secrets by suggesting it.)

Flick’s Great Idea

[Spoiler alert for The Sword of Shannara]

I recently wondered whether the Mythbusters might have a problem with a scene in The Sword of Shannara. The scene is this: The company from Cullhaven have been traveling through the Wolfsktaag Mountains, and a group of Gnomes has spotted them and set fire to the forest. The group hurries forward and makes it out of the trees, but the path behind is cut off, and the Gnomes are presumably not far behind. They make their way to the Pass of Noose, where they expect to cross a rope bridge, which they could then cut and leave pursuit behind. But when they get to the pass, they find that the bridge has already been cut, on their side. It dangles from the cliff face on the far edge of a (relatively small) canyon. It looks like they’re trapped.

Suddenly, Flick has an idea – one of them can fire an arrow with a rope attached to it into the wooden planks (or ropes, or whatever) of the bridge on the far side, then haul it back into place so the group can cross. Fortunately, the shot is successful, and they haul the bridge into place, just in time to tie it off, cross, and cut the ropes on the other side.

So here are the issues that have me a little worried:

1. The rope would add weight, causing the arrow to lose altitude. In theory, you could compensate for this by aiming higher.
2. The rope would have to be fed out pretty fast, or it would pull back on the arrow as soon as the slack was gone. I supposed you could toss the coil over the edge before firing, so there would be nothing to unwind.
3. The rope would prevent the arrow from spinning, which would make it very hard to aim, not to mention the additional drag from air resistance that you’d get the moment it stopped pointing straight forward.

#3 seems like a big problem. I don’t remember exactly how wide this gap was, and I guess you might not have to be super precise – if the barbs on the arrowhead could be made to catch among some rope, that might be enough to let you pull it back up on the other side. And if the rope were thin and light enough, maybe the arrow could even spin for a while before the rope became over-wound. Let’s just tell ourselves that and call it good. After all, the group made it through, so it must be possible, somehow.

Laser Rooms and Password Screens

I’m a big fan of lasers. They look cool, they do cool stuff, and the word even sounds cool. (Did you know it’s an acronym?) Maybe that’s why it kind of bugs me when they are misused in supposedly-realistic fiction. Like in movies and TV shows, where there’s a room full of lasers protecting a room or a vault or something. Here are my complaints about that:

1. Lasers are light beams, so you can’t see them unless they hit something. If you could, you’d see sunlight coming out of the air, and you couldn’t see anything at all because of the glare. So unless there’s dust in the room, if you can see the lasers in one of those laser rooms, you already know that the movie or TV show has screwed up. (And if you can see dust without the intruders putting it there, that’s fake too – why would you want the lasers to be visible if you’re the one they’re protecting?)
2. There’s always a path through them, for someone athletic enough. Why? Given the number of lasers in these rooms, you could easily just make a dense grid, instead of spreading them out across a wide area, creating person-sized gaps.
3. When they move, that looks like added security, but it’s also totally fake. Laser sensors work because a sensor in the wall is continuously picking up the laser light. When you step in the way, the signal stops, and the alarm goes off. If the laser is moving around the room, you’d have to have the sensor moving around the room too, which you couldn’t do (and which is clearly not happening in shows that do this).
4. When the lasers cut stuff, that also feels a little off. Of course lasers can cut things, but it would take a lot of power to have them on, and of course the “sensor” on the other end would have to be absorbing the laser energy somehow. It would be a lot more efficient to have the lasers just be sensors, and then have guns mounted in the wall that fire when the sensor goes off.
5. In movies and TV, these elaborate security devices never, ever work. Have you ever seen a laser room in a show that the person trying to break in didn’t get past? I didn’t think so.

Speaking of things that never work, I just remembered something else that always happens in fiction that bugs me so much that I added it to the title: People logging on to other people’s computers. I’m not talking about someone’s house, where there’s no password at all. I’m talking about folks guessing a one-word password, or just glancing over at the screen of some employee who has been lured away from his or her desk. No self-respecting corporation lets its employees leave computers unlocked or pick passwords that are a single word from a dictionary. Sure, you could probably crack most people’s passwords with brute force software (that is, guessing thousands of times in quick succession). But a human guessing words? Not a chance. But it happens all the time in even the most “serious” tech-fiction.

There. I’ve said it. I feel better now.

Pluto

When I first heard about Pluto not being called a planet, I didn’t care much, but it did seem like an instance of scientists getting overly picky about technical terms for colloquial concepts. (This happens all the time in biology – like trying to distinguish between “true spiders” and other spiders. Like it matters – they’re all evil monsters [or as my brother would say, “pure darkness”].) But after listening to the professor in one of the introductory astronomy classes I took in college, I’m convinced. It’s not a planet. It shouldn’t be called a planet.

The beginning of the argument is that there are all sorts of icy rocks like Pluto orbiting the sun beyond Neptune (or crossing its path like Pluto does). They have weird orbits and sometimes become comets. Pluto is the biggest of these Kuiper belt objects, but that’s not really that special. What really convinced me, though, is the matter of Ceres. Have you ever heard of the planet Ceres? I didn’t think so. See, a while ago they discovered a big rock between Mars and Jupiter, roughly spherical and maybe even with some atmosphere. They named it Ceres and classified it as a planet. Then they discovered another rock. Then another one. Then another one. And pretty soon it became clear that Ceres didn’t count as a planet because it shared its orbit with all sorts of random little rocks. The fact that Ceres is bigger than the other rocks doesn’t make us want to call it a planet. It has hydrostatic equilibrium (an awesome way of saying that is has enough mass to smash itself into a sphere), but it hasn’t cleared its orbit of similarly-sized objects. So we don’t call it a planet.

The thing is, Pluto is just like Ceres, only a little bigger and a lot farther away. Yes, it has a moon, but so do some asteroids. So unless you want to lobby for calling asteroids “planets”, you pretty much have to accept that Kuiper belt objects don’t count either.