Monday, April 27, 2015

Before and After the Scientific Revolution

It's easy to take for granted how quickly modern technology develops because the scientific revolution, which began in the 16th century, has been in full force for as long as anyone can remember. To offer some perspective on just how important this is, consider the differences in technological advancement before and after the scientific revolution was in effect:
  • In a roughly 300 year span of the 13th-16th centuries, purely mechanical clocks (that is, ones that don't rely on the metering of water) went from chiming just hours to ticking seconds.
  • In a roughly 300 year span of the 17th-20th centuries, human propulsion went from the horse-drawn carriages to rockets that took us to the moon.
Both of these advancements represent the pinnacle of technological and scientific thought at the time, but things have moved notably faster since the beginning of the Scientific Revolution. In my opinion the magic behind modern technological advancement is being able to use mathematics to characterize reality. This was the key to unleashing the floodgates, and so began the rush in the 16th century which has continued to this day

Wednesday, April 22, 2015

CafeSci Boston - April 2015 "Why 60 Minutes? 5000 years of tradition and science."

Last night I spoke at CafeSci Boston for the Cambridge Science Festival. I had a great time and the audience was lovely. The title of my talk was "Why 60 Minutes? 5000 years of tradition and science."

Unfortunately official recordings don't start until next month, but my wife managed decent capture herself:

You can follow CafeSci Boston on Twitter at @CafeSciBoston

An earlier article version of this talk can be found at:
http://www.livescience.com/44964-why-60-minutes-in-an-hour.html

The talk is based on a passing mention in the following book:

Page 4:
Several centuries of continuous [Mesopotamian] observations provided an invaluable body of data for the computation of planetary periods… As it would have been an overwhelming task to convert all these data into the decimal system… the Greeks maintained the sexagesimal system for astronomical measurements… This was also adopted by the Indians as early as antiquity… Then… it reached the Muslims who in turn transmitted this notation to medieval Christian Europe. The sexagesimal division… still used today is thus a living witness to the sexagesimal base once used by the Sumerians… in prehistoric times.

Here's some books that helped me stitch the narrative together:

And more generally about the history of mathematics:

Monday, April 13, 2015

ACS Chemistry Champions

Last week I made a video for the ACS Chemistry Champions contest.

You can see the rest of the entries here.

I had fun making this, and wish all the entrants the best of luck.


The History of "Using Equations and Stuff"

As a kindergartner falling madly in love with science and science fiction, the chalkboard had a symbolic mysticism to it. It was a place where brilliant people made discoveries and had eureka moments. A person could walk up to a chalkboard knowing only a little bit about something and after writing some symbols down, “A-HA!”, walk away knowing a great deal more about that something. I wished that someday I too could wield the power of this symbolic magic, and that I too would have eureka moments. It took more than a decade for me to get my kindergartner's wish, but it did come true.

Today I want to share the history of humans wielding such magic. Let’s explore an example:

What happens to the liquid level when a floating freshwater cube melts in a glass of heavily salted water?

Your instinct might be to run to the kitchen and give it a try, but don’t; we can get an answer much faster with only a pencil and paper. I didn't know the answer to this question when I first stumbled upon it, so did what any trained scientist would do: I sat down, drew some diagrams, did some algebra, and got an answer in a few minutes.

DISCLAIMER: It’s not at all important that you understand the following bits of math. Today I'm only interested in the historical and philosophical significance.


The water level will go up. To folks trained as scientists this will be trivial, but to most folks this will be indistinguishable from sorcery.

Briefly, Δh is the height of the water level. If it’s positive, the level went up; if it’s negative, the level went down. My goal was to figure out whether Δh is greater or less than zero based on the other things I could hypothetically determine if I were actually doing the experiment. In my final evaluation, all I needed to know was that salt water is denser than freshwater and that densities, masses, and areas can’t be negative.

Let’s take a step back to think about this. I didn't know the answer when I sat down… yet I was able to figure it out with nothing more than pencil and paper. Who was the first person to solve a problem in this way? Did they live in Ancient Greece? Rome? Maybe Classical India? Perhaps the Golden Age of Islam? Or Medieval Europe? Nope, nope, nope, nope, and… nope. This achievement certainly came after 1687. Why? Because I used two of Newton’s (1642–1727) three laws of motion, and 1687 is the year these laws were published. This fashion of solving physics problems came even later because Newton actually published his work in the tradition of Ancient Greek geometry; algebraic versions came later.

Newton’s forerunners were Galileo (1564–1642) and Kepler (1571-1630). Galileo’s model was a truly (perhaps the first) theoretical model because he showed that a simple rule like “constant gravitational acceleration” manifests in an observable phenomenon; namely, the parabolic motions of projectiles. Kepler's work on the other hand, while is often referred to as his “Laws of Planetary Motion” is more correctly called an empirical model; namely that planets follow elliptical trajectories around the sun.

An empirical model falls short of a theoretical model because it only proposes that data follow some mathematical shape without offering any reason why. Seventy years after Kepler published his model, Newton determined a theoretical basis in a new theoretical model called the "Law of Universal Gravitation" (which states that the gravitational force between two bodies is directly proportional to the masses of those bodies and inversely proportional to the square of the distance between them). Galileo’s work turned out to be a subset of this law. As for why Newton’s Law of Gravitation works, scientists are still trying to figure that out.

There was no such thing as a theoretical or empirical model (at least not relating to motion) before Galileo and Kepler. Before this there were variations of Aristotlean motion such as the theory of impetus. These ideas, in addition to being outright wrong, had no mathematical basis whatsoever. There is, however, something to be said about models relating to geometry: A theoretical example is Eratosthenes’s 240 BCE determination of the circumference of the earth, and an empirical example is Bhāskara I's 629 CE method of approximating sines; neither of these models characterize motion.

That mathematical models could be used to describe reality (and motion in particular) was the key to unleashing the floodgates of the Scientific Revolution, which began in 16th-century Europe and continues to this day.

The discovery of being able to use symbolic math to characterize reality is, in my opinion, the greatest intellectual achievement ever made by humans. Virtually every technological advancement of the last 300 years owes thanks to the practice of applying algebra to the physical world.

Friday, April 10, 2015

The Wrong Answer From a Little Bit of Right

Example 1:
"I checked my odometer; it's a shorter distance to go over that big hill than around it. Going over will save gas. Don't worry about the gas us use getting to the top of the hill; you'll get all that energy back when you start going down again."

No. Unless you intend on not using your brakes all the way down the hill, the vast majority of that hill-climbing energy is converted to heat (IE wasted) as the brake pads rub against the wheels. You're right only if you're okay with driving 90 mph when you get to the bottom.

Example 2:
"Fizz keepers don't work. Solubility of CO2 is only influenced by the partial pressure of CO2 in the container. Since air has negligible amounts of CO2, pumping air into the container won't do anything at all."

No. It turns out adding pressure from an inert gas slows the speed at which CO2 leaves the soda by lowering diffusion in the gas phase. Fizz keepers work, just not indefinitely.

Example 3:
"Because of the second law of thermodynamics, larger temperature differences between fridge's interior and exterior translate to greater efficiency. Therefore, your refrigerator uses less energy when it's hot outside."

No. The rate of heat transfer across the refrigerator's walls is proportional to the temperature difference between the fridge's interior and exterior. While your refrigerator might use less energy to cool down the air inside, it has to do so more often, so more energy gets used.

---

You'll notice a theme here: each statement starts off by outlining a bit of knowledge, but still gets the wrong answer. I can only tear into these lines of logic because hindsight is 20/20. I, at one point, thought all of these were correct. 

What kills me is how much sense such statements seem to make until you know better. The real world is complicated. The only way to get good at explaining it accurately it is to make mistakes, but also recognize and correct prior mistakes as more knowledge is acquired. A little knowledge goes a long way... but if it stays little it's likely to cause damage or waste you money.

Two Kinds of "Coincidence"

Two kinds of "coincidence" that at first glance, might seem kind of similar.
  1. The moon and sun are about the same size when viewed up in the sky. This makes solar eclipses really neat to look at.
  2. The time it takes for the moon to rotate and go around the earth are the same. From this, the same side of the moon always faces the earth.
There is a huge (HUGE) difference between the nature of these two coincidences. To find out, all you have to do for each example is ask "Why?".

For the 1st example, it's just dumb luck it worked out that way. The moon can orbit the earth at any distance; there's no reason why it should appear the same size as the sun. For the 2nd example, tidal forces lock the moon's period of rotation to be the same as it's period of revolution. If you're interested in learning more about this you can watch my video here: http://www.youtube.com/watch?v=Spz_IHYeoLY

The point I want to make is the 2nd example has a much more satisfying answer than the first. "It just is" is an answer that has never satisfied anybody, but it turns out most good questions have answers that have a lot more substance. I didn't understand the significance of this difference until late in high school. Coming to understand this difference was life-changing for me at the time; it made me care about science in completely new ways.

There are real reasons for say, why a ball's trajectory traces the path of a parabola, or that a plant gets four times as much light when it's half the distance from a bulb, or that exponential functions perfectly model the decay of radioactive atoms, or a cue ball stays still when it smacks another ball straight on... none of these are dumb-luck coincidences. There are perfectly satisfying answers for "Why?" in all these cases.

I was lucky to find satisfying answers before I stopped asking "Why?". Tragically, I think most people don't. There's a lot to be gained in re-invoking people's curiosity.

The Quest for the Oracular Chalkboard

One evening I was writing a video script about ice-melt. I had to take pause because I wasn't sure if water level goes up or down when a floating freshwater cube melts in saltwater. I did what any practiced scientist would do: I made a sketch, assigned some variables, did some algebra and got an answer in a few minutes: it goes up. I've done this in my career as a scientist more times than I can count, but because I was trying to communicate this to a general audience, something hit me:“I wanted this…” For years as a child I wanted to be able to do this very thing, wondering if it was real.

As a kindergartener falling madly in love with science and science fiction, the chalkboard had a symbolic mysticism to it. It was a place where brilliant people made discoveries and had eureka moments. A person could walk up to a chalkboard knowing only a little bit about something, and after writing some symbols down, “A-HA!”, walk away knowing a great deal more about that something. I wished that someday I too could wield the power of this symbolic magic, and that I too would have eureka moments. It took more than a decade for me to get my kindergartener’s wish… but it did come true.

I remember thinking when I was eight, even though I’d been doing math for as long as I could remember, it looked nothing like the kind that scientists used. First and foremost, my math didn't have any letters in it. The matter was simple; once my math had letters, I’d start having eureka moments. To this day I can recall my sheer disappointment when the first letters came in the form of “Line PQ” and “Triangle ABC”; ten-year-old me would have to wait a while longer. The next year my teacher let us in on a secret after a week of doing the sort of problem where you have 6 oranges on one side of a balance and 2 oranges and a mystery box on the other. “This is algebra,” she explained, “just label the box as x.” I remember being excited. To say this feeling was premature would be an understatement. The wait continued.

The start of middle school set the stage for more disappointment. Letters (variables, rather) were used in formulas like the area of a triangle, the period of the wave, the quadratic equation, etc. I felt cheated that formulas "seemed to be about more math” rather than the real world. Things like finding the heights of a tree with a protractor were neat, but hardly what I was after. The other source of constant torture was my calculator. Even though it was the kind the school had told me to buy, it had all these mysterious buttons on it. Nobody could tell me what the “cosh” or the “Σ” button was for. They looked science-y and there they were… taunting me. All I could get from teachers was "just wait." Mind you, this was before Google so I was on my own.

The chapter introductions to the school math book had these interviews with people who use that chapter’s math in their line of work. In one example a policeman explained a formula that used a square root to determine a car’s cruising speed from the length of skid marks. If I’d had the words to ask at the time, they’d been along the lines of “So, is there a real reason for using a square root, or did somebody just notice that the graphs for skid marks and square roots kinda match?” Other formulas would show up in science class (such as the period of a pendulum) but since nobody would show me where these formulas came from I began to suspect that scientists created formulas just by trying different arrangements of variables until some formula just happened to match data and/or units worked out. It did occur to me that the graph of a quadratic looks exactly like a ball flying through the air, but I didn't know how to ask if this was by coincidence or for a real reason.

With high school starting I began to believe the oracular chalkboard was a myth. I remember thinking that the chalkboard scenes from “The Day the Earth Stood Still” must have been glamorized. I continued to be unimpressed by the now common formulas in geometry, algebra, trigonometry and chemistry.

When I was 16 I placed into advanced physics. I went in not expecting much, but I was in for a surprise. Just in the first week it was clear just how wrong I’d had it; the oracular chalkboard was REAL. For the first time it was clear that math describes real-world phenomena for real reasons, and because of this, anyone who knows algebra can use math to learn about the real world. I remember feeling silly for suspecting otherwise, but considering how long I waited…

My last year of public school I took advanced chemistry and calculus. My experience was much the same as that in physics, and this would continue on as a college student of chemical engineering. It was plain as day now: because math describes the natural world in profoundly effective ways, to learn from the natural world we do math.

Here’s what kills me: Most people don’t take algebra-based physics in high school or college. Most people don’t get to see firsthand how someone can walk up to a chalkboard and teach herself something without doing an experiment. If I hadn't had this opportunity before leaving high school I could have easily went the rest of my life thinking the oracular chalkboard was a myth. If the average person isn't given the tools to experience this first hand, I think they should at least be able to consider the implications. I think most people understand that algebra is a tool that scientists use all the time, but they have no idea how or why it’s used.

In my experience, the average person has some vague notion that algebra is somehow powerful and that somewhere scientists use it for… something. The average person doesn't know it can be used for everyday musings such as freshwater cubes melting in salt water. It’s as if we’re showing children the various contraptions of a helicopter year after year, but most have no idea the blasted thing can fly. Only a select few students get to the point where they understand “Yes, I just saw a machine take off into the air. Yes, this is real. Yes, I can learn how to do this myself. Yes, I can use this tool to explore the world in a whole new way.” Without this perspective, it’s no wonder many opt to abandon the machine on some rooftop to rust.

There are plenty of skills that are by no means required to succeed in life: playing music, drawing, dancing, cooking, or speaking a foreign language. To respond to xkcd’s question over why people are so proud to have not learned math: with these other skills it’s clear the sort of amazing things that can be accomplished with mastery of those skills. I think people who take pride in never having used algebra literally have no idea the kinds of amazing things that can be done with it.

My two cents. Thanks for reading.

Tuesday, April 7, 2015

What Are Quadratic Equations?

New article posted on LiveScience.com today!

If you've ever wondered where the quadratic formula came from, now you can find out.

What Are Quadratic Equations?

parabola rotation, quadratic equation
Cheers All.