History of Science

I’ve been learning about the History of Science courtesy of Crash Course. It’s really interesting.

I first found out that the history of science was fascinating from Connections by James Burke. This was a PBS series back in the day (the late 1970s) (and it’s not really PBS, since it came across the pond from the BBC), and each one traced a series of scientific and technological discoveries from ancient to modern times. The first episode traced the invention of the plough to modern power blackouts. While the show looks dated (hey, it’s over 40 years old!), if you can get past that, it really rewards viewing. You can watch it on YouTube here.

Anyway, the YouTube playlist for the Crash Course History of Science is 46 episodes long, so I have some watching ahead of me.

#crashcourse

4 different reading levels

Do you know how to read?

At this point, since you’re reading this, I expect so. But it turns out that there are different levels of reading, depending on your ability and what you’re trying to learn. Each level builds on the previous levell

Elementary Reading

This is the simplest level of reading, when you just want to know what this sentence says. This is what you’re doing when you’re learning a foreign language.

Inspectional Reading

This is used to find out what the book/article is about. It can be done with skimming or superficial reading.

Skimming is when you read the different headings to get a gist of the structure, then go back to the beginning and read the first few sentences in each paragraph. This will give you the overall idea of the article, but nothing like real understanding.

Superficial reading is when you just read. You read every word, one after another. This is what we usually do when reading for pleasure, so it’s probably what you’re most used to doing. But again, it isn’t really about understanding.

Analytical Reading

This is where we get into really thinking about what we’re reading, but it takes more time and effort. You ask questions about what you’re reading and organize your thoughts. You take notes on what you read; perhaps have a bit of debate with the author. You’ll understand the material much better.

But we’re still not done.

Syntopic Reading

Instead of reading just one book/article, read different ones from different points of view. You actively compare the different books, evaluating the evidence and analysis provided. This is the highest level, and the most demanding of both time and effort.

When reading in school, at least in middle school, it’s best to be doing Analytical Reading. Think about what is being said. What does it imply? Are there things that are missing or that you’re confused about? Write things down in your own words summarizing what the author said.

Terminal Velocity

Today I went skydiving with my son! First time for both of us. Until you’ve done lots of dives you have to go in tandem with an experienced skydiver. So we went to the Sussex Skydiving, and checked in. We each got hooked into one half of a tandem rig. Then we went up in the airplane to 14,000 feet (along with our instructors and the other people jumping). At that altitude the plane leveled off and pairs started jumping out.

First the instructor attaches you to their suit (the other half of the tandem rig). He tightens the straps so you’re up nice and snug, as one unit. Then we moved together to the open door, and I put my feet out. My instructor then pushed us out of the plane.

The first few seconds were somewhat disorienting, but I quickly got my bearings and started hooting and hollering. Of course, now that we were falling up to 120 mph the wind was so loud I couldn’t hear anything!

So the title of the post refers to the maximum downward velocity, in this case 120 mph. At this speed the downward pull of gravity is canceled out by the drag of falling through the air, so this is the fastest we went going down. We had about 60 seconds of free fall. Now, it turns out that in tandem jumping the instructor uses a drogue chute to stabilize the two of you. This means our drag was higher than without it, so our terminal velocity was lower. Also, two people falling in a tandem rig would have more weight for the amount of surface area, and their terminal velocity (without the drogue) would be higher. So I don’t really know what a single person’s terminal velocity would be.

Then the instructor pulled the chute and we slowed down. The chute provided much more drag, so our terminal velocity was less. Finally we landed back at the airport. For this the instructor had us dive, then level out just above the ground. We stuck our feet out in front, and hit the ground. Our forward and downward momentum was very low and we skidded for a few feet before stopping.

So Rileysci, how was it?

It was very exciting! Certainly more thrilling than large roller coasters. But I’m kind of old, and I had issues. Isome ear pain when going up in the airplane. Surprisingly, I didn’t notice any pain on the way down, but my body was overwhelmed with other things at the time and didn’t notice. While going down with the chute open I was kind of dizzy, probably from my nervous system being overwhelmed. It’s taken a while for my body to get back to equilibrium (yay homeostasis!). Overall it was something to check off my bucket list, but I won’t do this again.

My son enjoyed it much more and will definitely be doing this again before the summer ends.

#sussexskydiving

Music for Oscilloscopes

First, a story:

Many moons ago, before laser pointers were things you could get at your local convenience store for the cost of a few packs of gum, back when lasers were expensive and cool, my friend got a laser. I’m pretty sure it was discarded by some lab. It was a tube about 5 cm in diameter and about 30 cm long and had a large brick-sized power supply. It was fun to play with, but ultimately it’s just a laser making a red dot on the wall. So Phil, for that was my friend’s name, took a speaker from his stereo, and taped a small mirror to the cone. Then, with the lights out, aimed the laser at the mirror and played music. Suddenly, the music came alive on the ceiling where the laser was being reflected. We called it Philsarium, after Laserium, which had been shown in the 1970s at planetariums.

That’s it for the story. Not much of a moral, I admit, but it was more of a trip down memory-lane. Anyway, the reason I bring it up is this week I saw a certain Smarter Every Day video. This video immediately brought that experience back to mind, except this time the laser is replaced by an oscilloscope. Oh, and instead of using regular music, awesome people in Austria craft music specifically to show different things on the oscilloscope. What normally shows sine waves or square waves (or RS-232 signals that Phil and I had to reverse engineer at one point) now shows everything from Tetris blocks to Tyrannosaurus Rexes.

Like Phil’s laser, the oscilloscope also shows a dot. Normally it shows various waveforms for analysis, but really it just shows voltage visually. By splitting the music’s stereo signal into 2 lines (one for the left speaker, the other for the right) and connecting these 2 voltages to the oscilloscope’s two inputs, the oscilloscope’s dot can be moved around the screen based on what the music does. One input (say the left audio channel) controls the horizontal, and the other input controls the vertical, moving the dot around the screen. By adjusting the voltage for the two channels carefully, you can turn the oscilloscope into an Etch-a-Sketch. And by having the sound change the drawing changes, and you can move and change the image. OK, it may be a long way to go for what is today considered mere music visualization, but doing it on a ‘scope is brilliant.

Those wacky Austrians have made albums of music based on this. The music is constrained by it’s primary audience, the oscilloscope, so it sounds somewhat like raw old school synthesizer music.

There’s a lot of trigonometry involved in this, so the next time a student asks a math teacher “when will we use this”, the answer may be “when you form a band.”

No detectable alien civilizations at 60 million stars

Breakthrough Listen has been looking (listening?) for alien life in our milky way galaxy and at the 100 nearest galaxies. They’ve been specifically listening in areas of our galaxy where the stars are more closely packed: the galactic core. They examined over 60 million stars, but haven’t found anything significant.

My hypothesis

I think that we’re unlikely to find signals from alien civilizations because I think we’re looking for the wrong things. I look at it this way: we’ve been looking for the kind of signals that we put out. Stuff like radio waves. That makes sense given our history; we’ve been dumping radio waves for over 100 years. But that presumes that aliens would similarly be putting out organized electromagnetic radiation. What if the hypothetical aliens have come up with a more efficient way to send information to themselves. What if they’ve stopped using radio, etc.

Perhaps they’ve shifted to using tightbeam laser communication. That wouldn’t be sending signals all over the place, just to the destination. It’s also more energy efficient.

It’s like using listening for AM radio signals, but the people you’re listening for have switched to FM. The way of encoding information is different, and could just appear as random static.

If intelligent life out there is using some method to communicate that we haven’t thought of, then we may not be able to detect them, even if we’ve scanned their system for signals.

Of course I don’t have a solution to this problem. I know much less than the experts on what other methods intelligent life could be using to communicate; I’m just a middle school science teacher. I’d love to find evidence of alien intelligence. I just think that we’re looking for a needle in a haystack where no one is allowed to access the haystack directly.

I think that we may find extra-terrestrial life, but it won’t be intelligent life. It’ll be something like bacteria. Perhaps life is relatively common, but it doesn’t evolve to what we think of as intelligence. How would we know if there were a habitable planet within 50 light years that has life with the intelligence chimpanzees? They wouldn’t be broadcasting anything.

COVID-19 herd immunity? Not so fast.

Herd immunity (or community immunity if you like rhymes) is the point when enough of the population has been immunizes so that a disease can’t spread much. Maybe only a few people get sick, but outbreaks are stopped because there just aren’t enough vulnerable people around for the disease to spread.

And boy, would we just love to get to that point with COVID-19. But at least in the USA it doesn’t look like we’ll get there. Why? Because you need enough of the population immunized. Something around 80% is needed(it varies depending on each disease’s R number). But with about 25% of the population here refusing to get immunized, we may never reach it.

Anthony Fauci isn’t talking about getting there anymore. He’s shifted to trying to get as many people immunized as possible. Others are more explicit:

“It’s theoretically possible but we as a society have rejected that,” said Dr. Gregory Poland, director of the Mayo Clinic’s Vaccine Research Group. “There is no eradication at this point, it’s off the table. The only thing we can talk about is control.”

— Dr. Gregory Poland from an article in USA Today

Control. Not the nice kind where we’ve beaten the disease. The kind where we have to be careful for a long time. These anti-vaxers are just making things worse. It’s called a conspiracy theory for a reason: it’s like circular reasoning and non-falsifiability. i.e. not science, and not trustworthy. It’s like these people are afraid of critical thinking.

Sigh.

Let’s just hope we get there in spite of them. Maybe some parts of the US will get herd immunity while others just won’t have enough people who believe in science.

Fundamental Equations, Chaos, Fractals, and Leaky Faucets

It’s been a while since I’ve written here. Busy teaching. (I know, lame excuse).

So I go and watch some video on YouTube, and on the side is the list of suggested videos. For a while there’s been this one by Veritasium (Derek Muller). Now, Derek is a fantastic science educator, and is who I want to be when I grow up. One problem is he’s younger than me by over a decade. Hmm. Have to work on that somehow.

Anyway, the video that was just waiting for me to finally click on it was this one. It’s about an equation that will change how you see the world.

The Logistic Map

The math is very simple: x_{n+1}=r x_n(1-x_n) where r is the growth rate. This is a very simple equation with a negative feedback loop.

When you graph r by the equilibrium population, you get this:

from the Wikipedia article on the Logistic Map

What!?

Once the growth rate hits 3, the equilibrium population splits, and oscillates between two values. Then just after 3.4 it splits again. And very soon it becomes chaotic. Oh, and fractal. The chaotic nature was used for pseudorandom number generators.

The Mandelbrot set

Does mentioning fractals make you think of the Mandelbrot set? If it doesn’t, then you have some research to do.

From the Wikipedia article on the Mandelbrot Set

It’s probably the most famous fractal out there. Heck Johnathan Coulton has done a song about it.

But evidently if you somehow rotate the Mandelbrot Set along it’s real number axis, you get this:

From Physics Forum

Look familiar? At this point I started getting a headache, but it was one of those good, excited headaches that come from having your reality twisted about.

Leaky Faucets

Oh yeah, leaks. Derek then mentions that if you get your faucet going drip, drip, drip, and then increase the water pressure just right, it will start doubling: drip drip, drip drip, drip drip. Push it a little more, and you get chaotic behavior.

Of course the YouTube video is so much better than my explanation. Go watch it.

Are you Mind Blind?

How well do you visualize things you remember or imagine? Try to imagine this: You have climbed to the top of a hill. You scramble to the top of some rocks. Ahead of you, past some more hills with trees on them, is a mountain range rising above the hills. The sky is mostly blue with a few fluffy clouds, and a plane going by leaving a contrail.

How well did you visualize that? Could you see it in your mind’s eye? Or was it just a description without an image?

If you couldn’t visualize it, then you may have aphantasia, a condition that 2-5 percent of people may have. This can affect how well we can recall things, to how we can imagine the future, and even dream.

See links for more information:

  1. Being ‘mind-blind’ may make remembering, dreaming and imagining harder, study finds
  2. A cognitive profile of multi-sensory imagery, memory and dreaming in aphantasia

Happy Summer Solstice

How would you like to watch the summer solstice sunrise or sunset at Stonehenge?

The solstices are the two days when the sun is the furthest north or south from the celestial equator. The full path that the sun takes over the year is the analemma. The solstices are the furthest north and south points on the analemma.

Stonehenge is one of the most well known monuments. The ring of standing stones was built between 3000 BCE and 2000 BCE. This English Heritage website is doing/has done livestreams of sunrise and sunset from the site.