What does the Oumuamua asteroid have to do with climate change?

Yes, there is a sort of connection.  OK, it’s not connecting the asteroid and climate change—but rather these two ideas help us understand the nature of science.


I’m going to start with Oumuamua (which is fun to say out loud).  In case you aren’t familiar with it, this is the name of the recently discovered asteroid that appears to be from outside our solar system. It’s a pretty big deal.  Here’s what we know.

  • Oumuamua is from outside of our solar system and it’s not a comet (because it doesn’t have a coma).  Oh, we know it’s interstellar because of the direction it comes from as well as it’s speed (too fast to stay in the solar system).
  • The asteroid is long and skinny and rotating.  We know this based on the changing brightness as it rotates.

Now for the weird part.  If you just use the gravitational forces on the asteroid, it should move in a different path than it does.  So, why does it deviate from a purely gravitational trajectory?  We don’t know for sure.  One option is that there is a tiny force from the interaction with the sunlight that can push it.  In order for this to have a significant effect, the asteroid must either have super low density or be super thin.

Option B: the asteroid isn’t an asteroid but instead it’s an alien spaceship with thrusters.

OK, I didn’t get all the details perfect—but I think you get the idea.  It’s a weird asteroid and we don’t know everything about it.  Here, this video from Scott Manley gives a nice summary.

Oh, this article is pretty nice too (from The Verge).  But just to be clear—the motion of the asteroid COULD BE because it’s an alien.

Climate Change

I’m not going into all the details here (NASA does a nice job if you need more).  Let me just give the super simple version.

  • There is this thing called “The Sun”.  It’s in space and it radiates light in all directions.
  • Some of this light hits the surface of the Earth.
  • Some of the light that hits the Earth reflects, some gets absorbed and warms up the surface of the Earth.
  • When the surface of the Earth warms up, it radiates infrared light.
  • There is carbon dioxide in the atmosphere.  Carbon dioxide absorbs and re-radiates infrared.  This essentially makes the Earth warmer than it should be (this is good thing).  Oh, other gases do this too.
  • Humans add carbon dioxide to the atmosphere. Yes, by breathing—but we add a whole bunch more because we burn fossil fuels.  Oooops.  We added too much.

OK, that’s the short scoop.  Humans can measure the temperature of the Earth (not a trivial task) and they can measure the amount of carbon dioxide (this is a bit easier).  In the end, it seems very clear that humans add carbon dioxide and the carbon dioxide is warming the Earth and changing the climate.

Now for the Nature of Science

Science is the process of building models.  Science is NOT the process of finding The Truth.  In fact, we never know what’s absolutely true.  Here is my favorite example.

Take a ball.  Hold it out in front of you and then let go.  What will happen?  If you say “oh, it’s going to drop”—I agree.  That’s the most likely thing that will happen (since I’ve seen this like a million times).  But just because I’m very confident of the outcome doesn’t mean that it’s true.  The only way to find out if all balls fall when dropped is to drop ALL the balls ALL the times—like forever into the future.

OK, we can’t prove things are true but we can show when they are wrong.  If I have a science model that says all balls are red, I just need to find one ball that isn’t red and BOOM—I showed that was wrong.  This is just a fundamental nature of science.

Now let’s jump to publishing stuff in science.  Here, Katie Mack has a nice twitter thread on this.  Read the whole thing—it’s not long.

When scientists are writing about Oumuamua, they try to eliminate ideas.  They have collected evidence that the asteroid doesn’t move based just on the gravitational interaction, so they can eliminate that idea.

But what about aliens?  There’s not data that says it CAN’T be aliens.  Does that means it’s aliens?  Does that mean we think it’s aliens?  Does that mean that Will Smith and Jeff Goldblum need to steal an alien ship and fly into the mothership to upload a virus and save humankind?  No.

What about climate change?  Is it possible that there is something else going on other than human production of carbon dioxide?  Well, we haven’t disproven every possible idea.  Again, it’s possible that climate change is caused by aliens.  It’s possible, but unlikely—just like a released ball is just going to hover in the air when I let go of it.

When people (you know who you are) say something like this:

Oh, but only 97 percent of published papers in climate science say that humans cause climate change.  So, it could be fake.  We should burn more coal.  MORE COAL.

Well, how many published papers on Oumuamua include the possibility of aliens? Do we really think it’s aliens?

Someone needs to go through all the Oumuaua papers and calculate the percent of them that mentions aliens.





Fetch with Ruff Ruffman uses a laser to measure temperature?

I am sorry to point this out, but I can’t help it. My kids watch this show “Fetch with Ruff Ruffman”. It’s mostly an ok kids show. However, there was a problem. In one episode, some kids were in the desert and measuring temperature with (they said it several times and it was even a quiz question at the end) – a LASER. Here is the device they used:


This is an infrared thermometer with a LASER aiming system. The laser is only there to help you aim. The temperature is determined by measuring the infrared radiation from the object. You don’t even NEED the laser. Those ear thermometers work the same way, but they don’t have lasers.

I guess when a laser is involved, it just makes it so cool that it must be the most important thing. I am going to put a laser pointer on my computer – that way people can say “look, that computer runs on LASERS.”

Fun things to do with a green laser pointer

I went home for lunch today. While waiting, I saw this lizard. We have many lizards in Louisiana, I like them, really I do. So, this is what I did:

No lizards were harmed in the filming of this video.

I was really surprised. I thought for sure that I had tried this before and nothing happened. Maybe it was because of the white surface the lizard was on. Maybe it was because it was an older and wiser lizard (it was larger than normal). Maybe this is already a well known fact about lizards and laser pointers. Needless to say, this was quite entertaining and completely justifies the cost of my laser pointer.

People need to play with magnets

Question from class: *What do magnets interact with?*

Basically, everyone said “metals”. I am quite surprised. No one specifically indicated that magnets only interact with iron and steel (of the materials they would likely see). I understand that steel is a very common material they are likely to encounter, but what about aluminum? I think this points to the idea that very few of my students have actually played with magnets. This is a shame. Everyone loves magnets.

So, I propose you go out and give someone you love some magnets today.

Can you make an infinite number of playlists?

When mowing the lawn, I like to listen to podcasts. One of my favorites is [Buzz Out Loud](http://bol.cnet.com). This weekend, I was listening to episode 817 and one of the topics of discussion was MySpace and their DRM free music stuff. [Wired](http://blog.wired.com/music/2008/09/myspace-launche.html) had a description of what they were going to do. That is not my point. The point is the claim that you could make an infinite number of playlists. How about I calculate (or estimate) the number of different playlists one could make.

First, the idea behind the idea. Calculating the number of combinations is not my strong suit. I always get myself confused. So, if I make an error, feel free to point it out. [Wikipedia](http://en.wikipedia.org/wiki/Combinatorics) calls it combinatorics. Not sure if that is the real name for this stuff, but I guess it doesn’t matter.

Ok. Now for the parameters. The Wired story says that MySpace will allow playlists up to 100 songs. How many songs does one have to choose from? If it were my music collection, I have 2107 songs. I suspect that this is below average (the reason for this suspicion is that I rarely acquire new music so I figure my library is smaller than the norm). What about iTunes? How many songs are available on that? According to [wikipedia](http://en.wikipedia.org/wiki/ITunes_Store) there are 8 million songs you can pick from.

Continue reading “Can you make an infinite number of playlists?”

Computational Physics and a group of 1000 8th graders

I like computers, really I do. Computational physics is a good thing. However, there is a small problem. The problem is that there seems to be a large number of people out there that treat numerical methods and simulations as something different than theoretical calculations. You can tell who these people are because they refer to simulations as “experiments”. But what do these simulations really do in science? What is science really all about?


To me, science is all about models. Making models, testing models, upgrading models. Models. Some examples are the model of gravity. One such model is that there is a gravitational force between any two objects with mass. This force is inversely proportional the square of the distance between them. (This is Newton’s model). Is this model perfect? No. Is this model the truth? No. How did this model come about? Experimental evidence.


Well, how do you make models and what form can they take? To make a model, you collect some observations. The model should agree with these observations. This model could be a physical model (like the globe). It could be a mathematical model (like V=IR). It could be a numerical model – like a [vpython](http://vpython.org) program of a baseball trajectory with air resistance. These are all models.

**8th graders**

What does any of this have to do with 8th graders? I claim that any numerical calculation or simulation could be done with a group of 1000 8th graders rather than a computer. What does a computer do? (a computer program really) A program takes a problem and breaks it into a bunch a really small steps. It then does each of these steps and combines them together in some way. Just like a group of 8th graders with TI-89 calculators. Clearly, they are just computing something – they are not a separate type of science (other than theory and experiment).

Energy issues are like the reverse Y2K problem

There was this commercial on the radio about Trane heating and cooling units. The ad claimed that the units could use up to 50% less energy than your existing unit. This started me thinking (because before that I was in a complete state of non-thinking). Do you remember the Y2K problem? Basically, when people started writing programs back before Star Wars they had to be very conservative. The hardware of the time did not afford the programmers to have frivolous code. To conserve, they only used the last two digits to represent the year (1970 was represented as 70). Obviously this became a problem in 2000. So, for computers and programs, people started very conservative and the hardware became less conservative.

Now look at appliances. When people first started getting electricity in their house, it was a completely new thing. But how much electricity would a household use? At one point (I read somewhere) that it was projected that electricity could be so cheap it would be free. In this case, why make an efficient AC unit? Look at many of our energy uses today (including cars). They seem to have the legacy of being extremely inefficient.

To summarize: Computer programs start out being efficient and then go to not needing to be efficient (because computer processing is relatively cheap). Appliances start out being inefficient and are moving towards being more efficient. Really, that is all I wanted to say.

Significant figures what are they for and what do they have to do with uncertainty?

Suppose I am working on a problem and I wish to calculate the density of something. I measure the mass to be *m* = 24.5 grams and the volume is *V* = 10 cm3. In this case the density would be:
![Sigfig 1](http://blog.dotphys.net/wp-content/uploads/2008/09/sigfig-1.jpg)

ALERT! ALERT! ALERT! This is not a test!!!! Something is drastically wrong! Clearly I messed up. How can I have the mass measured to **3** significant figures, the volume measured to **1** significant figure, but the density calculated to **3** significant figures? Isn’t this a violation of some fundamental principle that could be worse than the Large Hardron Collider coming online and destroying the world?

No, we can all calm down. This really isn’t a big deal. Unfortunately many people (*hint* like chemists) do get all freaky about significant figures. Now calm down chemists. I am not saying significant figures are entirely stupid. They do have a purpose. What I AM saying is that they are not some fundamental rule that can not be broken.

So what is the deal with significant figures?

Continue reading “Significant figures what are they for and what do they have to do with uncertainty?”

Cat in the Hat sits on a throne of Lies!

My kids like books. Especially when they are going to bed. I let my daughter pick a book and she picked “Clam-I-am. All About the BEACH” by Trish Rabe. It is nice, it rhymes. The pictures are pretty. Then I get to this page:


So, the ocean is blue because of the sky? How do you get green oceans? How about brown (I live in Louisiana, trust me – the gulf of Mexico can be brown)? What about when you are underwater, everything looks blue. The best answer to why the ocean is blue is that that is what color does not get absorbed. All colors of light interact with the water. Reds are mostly absorbed, the blue gets scattered.

[Here is a better explanation from the Library of Congress](http://www.loc.gov/rr/scitech/mysteries/oceanblue.html).

Would it be so hard to have someone look over the science in a book? I would do it if they asked.

People in and out of a bar

So, I am still in Alabama because of lack of electricity in Louisiana (although we got power back last night – YAY!). My wife convinced me to go out and hear this band since we are staying at my parents and they said they would watch the kids. In general, I am way too old and crotchety to go out – but it appears I had no choice. Overall, it was not too bad except for staying out too late. (the band was actually pretty good – I think they were called [Fly By Radio](http://www.fly-byradio.com/) and they played 80s musics) The one thing I thought about while in the bar was the long line of people waiting to go in. At some point, the number of people inside reaches its maximum capacity. People still come in because some people leave. Here is my rough sketch of this: (I call it a bar graph – get it?)

![bar graph](http://blog.dotphys.net/wp-content/uploads/2008/09/bar-graph.jpg)

My first idea was to think of the bar as a capacitor and maybe this works. Ok, now I made something positive out of my trip.