Wednesday, August 30, 2017

More Science: The Universe Is Not Enough

Disclaimer: I recognize that there are important societal issues to consider when discussing overpopulation. This is a math/science post, so I'm planning to completely ignore those.

"Humans are overcrowding the planet!" is a concern that crops up at least once a generation. Up until now, I have had little patience with the doomsayers. The idea that a family's children after the first (or second or third) are a burden that the world cannot accept is disturbing and offensive to me. Yes, there are problems that come with larger populations, but I generally choose to trust in our ability to solve those problems.

For example, people have been predicting that we will run out of food at least since the industrial revolution. But the the Haber process (invented ~1910) let us create fertilizer, and was just one in a string of many important innovations that have allowed us to support more and more people. Over and over we have surpassed the supposed "upper limit" of sustainable number of humans, and in the process discovered amazing new things. Science!.

Moreover, I trust in the nature of large systems to be self correcting (i.e. parents can figure out whether they can support another child without me or an economist telling them, and those local decisions will be based on global resource allocation).

BUT! This video from Numberphile has convinced me that there is an inescapable upper bound, and that it is approaching far faster than I would have guessed. They calcualted the number of particles in the human body (~10^29), and in the observable universe (~10^80). So if there is nothing in the universe but people, we could make 10^51 of us. I think it goes without saying that that is a LOT of people.

So, no problem, right? This abstract idea is absurdly impossible, yes? NO! If you assume that the world population (now ~7 billion) continues to grow at it's current rate (a little over 1% per year), we have less than 9000 years before we run out of universe! And even though the video doesn't say this, that 9000 year cut-off applies even if we use not just the normal matter, but also the other 95% of the universe made up of dark matter and dark energy. Clearly, something will have to give before that point, and I'm not willing to bet that thing will be the universe.

Presumably there are some other obstacles in the way before we reach that point, but I think we can agree that we have established an absolute maximum, beyond which even the most optimistic would not try to push us.


And, in unrelated science coolness:

Wikipedia just taught me that the first discussion of gravitational waves (detected last year by LIGO - yay!) was by a scientist named Oliver Heaviside. Another instance of perfect naming. Good article on LIGO here.

Sierpinski's triangle (below) arises from various apparently unrelated things beyond the obvious stepwise removal of smaller triangles. You can find it from chaotic attraction, from the parity of Pascal's triangle, or from turning a line into a trapezoid iteratively. I only knew about the last one, and was surprised to learn that it shows up in other places this way.

Sierpinski's Triangle

Wednesday, June 28, 2017

Friday, June 9, 2017

Photosynthesis is Amazing!

One of my favorite scientific realizations is the idea that all of the trees and plants we see are basically solidified air. Photosynthesis is the process of using energy from light to turn air (carbon dioxide) and water into sugar, and that sugar is then used both as fuel and as a structural building block to make more plant.

I've wondered how much photosynthesis actually happens on earth, and recently looked up the answer. Current best estimate: 150-175 petagrams per year, or about 0.45 petagrams per day. A petagram is the same thing as a gigaton, but how much is that really?

The most useful comparison I found is that the mass of all living humans is 0.5 petagrams. So every day, plants and algae make enough sugar to rival the combined weight of humanity! Another way to look at it is that a cup of sugar weighs 200 grams. So 0.45 petagrams of sugar is enough to fill up Sydney harbor, or make a sugar cube half a mile on each edge.

Such comparisons aren't entirely fair, because all that sugar isn't just piling up into cubes. Plants use up about half of it as energy. And while the other half gets incorporated into new plant growth, plants are being eaten and converted back into energy just as fast. So really what we are measuring is the daily calorie intake of the planet, which is estimated at ~1% of the sunlight that reaches earth's surface. Hooray for photosynthesis!

Friday, April 28, 2017


Kelley and I were talking about space last night, partly because the Cassini probe completed a dive between Saturn and its rings, and partly because Jace has been been learning about planets. We watched this excellent video, which starts out comparing the sizes of various planets and stars, then zooms out to compare the scale of galaxies and more.

Such mind-boggling vastness can make one feel very small, so naturally we tried to counter that by thinking of the tiniest things in the universe. Here is the chart we came up with. Unfortunately, I got some things wrong, so please refer instead to the revised chart below it.

Here we have the revision with text labels and more accurate spacing. The axis is a log scale, so each step of 3 brings you to something a thousand times bigger or smaller.

A few of our observations:

  • It takes approximately the same step in size (~9 orders of magnitude=a billion* times bigger in diameter) to get from an electron to an atom, from an atom to us, and from us to the sun.
  • Two more of those steps take you from sun to observable universe, but the galaxy is well past the first of those. (This was the main error in my napkin version--the galaxy is approximately one billion solar systems across, not one billion suns.) Note: That is linear distance; our galaxy contains 100 billion stars. 
  • Two big steps in the other direction take you from an electron down to the Planck length (below which "distance" ceases to mean anything).
  • Once you contemplate the vastness of something a billion-billion-billion** times bigger than you, it is not helpful to say "Well, yes, but that's just the observable universe. The whole thing could not only be far vaster, it could truly be infinite."
For a great illustration of the bigger-than-us half of the chart, check out this xkcd image. If you want to look at an interactive zoomable chart with a lot more objects than mine, this is a good one.

*I use the American billion here. If you are feeling European today, feel free to translate to milliard.
**Octillion for Americans, or quadrilliard for the traditionalists.

Monday, April 24, 2017

Useful Tools: Books and Movies

This is the second in a series of posts recommending useful resources in various areas. These are apps or tools I use regularly. Today's topic is: Books and Entertainment.
All apps are for Android, and links will take you to the Google Play store. (website and app) is the standard portal for borrowing digital content from public libraries. I have checked out tons of ebooks this way. Reading them in the Overdrive app works fine, but when possible I get my books in kindle format, as I prefer the reading experience and features of the kindle app. I've also enjoyed many audiobooks from my library via Overdrive. (website and app) is another library content portal, with a different licensing system. If your library subscribes, this would be well worth trying out. Their book selection is much more limited, but most items are recent releases or other titles that Overdrive doesn't have. In addition, Hoopla has a broad selection of music, TV shows, and graphic novels. (It's how I listened to the Hamilton soundtrack and watched The Librarians). 

In contrast to Overdrive's model, in which a library buys a certain number of copies to lend (which results in waitlists for popular titles, and different collections available from different libraries), Hoopla's content is always available, with a limit on the number of items a patron can check out each month. So if Hoopla stocks something you want, you can get it right away!

My only complaint is that Hoopla's app does not deal well with orientation changes of your device. If you turn your phone, it will spend time loading the book again and probably lose your location. Make sure you lock your phone display into portrait if you plan to read something in the app. is the best book tracking website I've seen. I love it: for logging and reviewing books I've read, for finding and keeping track of books I want to read, and for seeing what my friends recommend. In most respects I find the app inferior to the web version, but it does have the incredibly convenient feature of adding books by scanning them. This used to be ISBN barcode-only, but a recent update added the ability to identify books from the cover. Strangely, that messed up the reliability of ISBN-scanning, but the cover-scanning feature works so well that I usually don't miss it. Adding a dozen library books at a time is fast and simple, which is great since I try to keep up with all of the picture books we check out. aspires to be Goodreads for movies. (At least, that's how I use it. I'm sure the creators have a somewhat different vision for their product, to judge from the number of features I don't use.) I use it to log and rate movies I see, but that's about it. I tried several similar websites, and this was the best one for my purposes.


Friday, April 21, 2017

Useful Tools: Commuting in Boston

This is the first in a series of posts recommending useful resources in various areas. These are apps or tools I use regularly. Today's topic is: Commuting in Boston.
Apps referenced are for Android, and links will take you to the Google Play store.
  • First, the item not specific to Boston: Shuttles operated by many universities and hospitals across the country are tracked by the TransLoc Rider app. I used this one both in Atlanta (Emory) and here in Boston (LMA/Harvard), and the real-time location data was helpful with knowing when to leave to catch the bus I needed. To find out if they have a system near you, check out their map or agency list.
  • For commuter rail in Boston, the website is the best of several tools I tried. The only feature that is missing there is upcoming departures of inbound trains. If that is something you need, this rail tracker app is the best alternative. I should also note that trains with missing location feeds appear in the app, but are absent on the website (with a notification at the bottom that the data is missing). Even so, the website's map makes it much more useful than the app. And, unless you have a monthly pass, you probably want to use the official mTicket app to buy commuter rail tickets.
  • For the city buses, I recommend BostonBusMap. This app is the best of several that I tried. There is a bit of a learning curve to figure out how to navigate the many options and views, but after that it is intuitive and full-featured. I tend to use "stops and predictions on all routes" as my default view and select the stop near me--especially since multiple routes serve my usual stops.
  • I haven't had much occasion to use any of the subway lines, so no recommendations on that front at the moment. Sorry.

Saturday, February 25, 2017


I had a wonderful time attending Boskone, the convention of the New England Science Fiction Association.

The guest of honor, and the reason I decided to go, was Brandon Sanderson. I was very excited about the opportunity to talk about his books with him and with other fans, and I was not disappointed. We got to discuss the magic systems and some of the background plotting in his books, along with his research and future plans.

You may recall a previous post in which I rewrote one of his epic fantasy series in the style of Dr. Seuss. I improved that draft and printed off a copy to give Brandon. You probably need to have read The Way of Kings to appreciate it. You can read it at the bottom of this post. I only managed to illustrate the first half of the book, but I am particularly proud of my Seuss-style illustration of Rysn, a character with ridiculously long eyebrows.

In addition to Sanderson, there were an impressive number of big-name sci-fi and fantasy authors at the convention. I signed up for a small group discussion with Jane Yolen and with Max Gladstone, and loved getting to meet both of them.

Jane has published over 350 books, including Wizard's Hall, the Commander Toad series, the Pit Dragon series, and How Does a Dinosaur Clean up His Room? The main character in Wizard's Hall was one of Sarah's primary inspirations for Shuyeh in our (still to be revised) Wanderfolk manuscript.

I particularly enjoyed meeting Max. He was clever, personable, and insightful.  Max is the author of the Craft Sequence, a series that I have described as "prequels done right." He wrote the different stories out of chronological order, with the idea that you could pick up any of them and read it as a self-contained novel. Together, they tell a story of global change across generations. In the Craft novels, magic is based on entirely on contracts, and is the lifeblood of the world economy. That means that magicians are all some flavor of lawyer, accountant, or financier. It also means that the climax often does double duty as high-powered action sequences and a dramatic courtroom showdown.

Other authors and artists who I met or listened to (but didn't chat with) include Michael Whelan, Jo Walton, and Ada Palmer. Quite a few of the presenters live here in Massachusetts, so I will be on the lookout for other opportunities to meet them at writing and fan conventions in the future.

Saturday, January 14, 2017

Monster Trucks!

Monster Jam is a traveling monster truck show, and you can try to guess which two lucky guys got tickets for Christmas. We went last night and had a blast!

My previous exposure to monster trucks was limited to the smash hit "He's a Monster" on Truck Tunes, so it was a brand new experience for both of us. Some things were expected and others were surprises.

At least a third of the audience was under six years old, and half of those were sporting cool earmuffs like Jace got to wear. It was a good idea to get those--the trucks were very loud, and you may remember that we had to leave early from a baseball game last year after the crowd cheered too much. With the "ear muffins," as he likes to call them,  Jace was enthralled.

There were 8 drivers competing in a half dozen races and stunt routines. They each drove three different vehicles: a monster truck, a four wheeler, and a speedster (basically an ATV with cab and crash bars). In addition, we got to see several loaders, forklifts, and other trucks. They all came out during an intermission to repair/reconfigure the obstacle course, and one specialty truck got to come out several times to help right an overturned truck.

As truck tunes will tell you, monster trucks do "wheelies, and donuts, and jump after jump!" The trucks are all functionally identical, with the same motors, wheels, and shocks under their fancy exteriors, so I was a little surprised that three of the drivers were consistently better at almost everything. A few of them just looked like they were bouncing over dirt mounds and turning in circles, while the better performers had impressive jumps and exciting spins. I guess I expected the truck's design or power to be the major factor, but it turns out that smashing things in a monster truck takes some actual skill.

I recorded Jace watching two of the best performances. In the second video, I miss the truck's finale, but you can hear the cheers. He balances on his front wheels for a moment, then flips up to smash the cars. (It looks like Monster Jam puts an official highlights video from each tour stop on their youtube channel. I'll update with a link when they do.)

 A big thank you to Kelley for the present so we could have an awesome boys' night out!