During the night of 11 February Physics Today's Facebook page acquired its one millionth fan (or "like" as Facebook confusingly calls fans these days). I don't know who that individual is, but thanks to the statistics that Facebook makes available to me as an administrator of the page, I can say who he is likely to be.
- • My use of "he" is justified: 75% of Physics Today's Facebook fans are male (compared with 54% for Facebook as a whole).
- • The millionth fan is 18–24 years old. Fans in that age group account for 47% of the total for the page.
- • He lives in India, where 30.1% of the page's fans reside. The country that has the next highest number of fans is the US with 12.2%. The rest of the top 10 comprises Pakistan (5.4%), Philippines (3.2%), Bangladesh (2.2%), Nepal (2.0%), Egypt (1.8%), the UK (1.6%), Brazil (1.4%), and Iran (1.2%).
- • Like 73% of fans, the language he uses on Facebook is English.
Amassing so many fans has been a mix of experience and luck. By 13 September 2013, the page had a respectable fanbase of 63 007 that was growing at the rate of about 500 new fans a week (NFW). Soon after—abruptly and without my doing anything differently—the rate shot up to 3000 NFW. It turned out that Facebook had tweaked the algorithm that determines which posts appear in users' news feeds.
The jump in fans was especially welcome because the tweaks were aimed at boosting the quality of posts. Facebook had surveyed thousands of its users to find out what makes a high-quality post. The tweaks were based on the survey's results. Evidently, the algorithm judges Physics Today's posts to be interesting, timely, engaging, and trustworthy—which is just as well: A page's fanbase grows when its existing fans share the posts with their friends, some of whom become fans themselves.
Even if you're not a fan of Physics Today's or even a Facebook user, you might be interested to learn what the page's million fans seem to like about the page. The first post of the day always commemorates the anniversary of the birth of a noted physicist or of a momentous event. Wednesday's birthday boy was Pierre Dulong. I wrote:
It's the birthday of Pierre Dulong, who was born in 1785 in Rouen, France. In 1819 he and Alexis Petit proposed a law that accounted for their experiments on heat capacity: A solid's heat capacity per mass multiplied by the substance's relative atomic weight is a constant. The constant turned out to be 3R—that is, three times the universal gas constant. Albert Einstein explained the physical origin of the Dulong–Petit law in terms of lattice vibrations in 1907.
The post, with its accompanying picture, attracted 2043 likes, 73 comments, and 445 shares.
Pierre Louis Dulong (1785–1838)
Also popular are astronomical images, which arrive in great quantities in my inbox thanks mostly to the efforts of Rick Fienberg, the press officer of the American Astronomical Society. News stories from Nature, Science, and other science media are also rich sources of posting material, as is the American Physical Society's Physics website.
I also post press releases. The news they contain is timely and interesting. The best ones, like those from John Toon and Brett Israel of Georgia Tech, do not indulge in hype or exaggeration. I'm also a fan of the press releases from the Optical Society.
Of course, I also post links to content from Physics Today, but such posts are in the minority. Physics Today simply doesn't produce content at a high enough rate to feed Facebook's appetite entirely.
Anniversaries and astronomical images aside, the most popular posts tend to be about fundamental physics. News about cosmology, quarks, or quantum weirdness can garner thousands of likes each. So far this year, the most popular post has been Zeeya Merali's news story in Nature about Stephen Hawking's recent paper on black-hole event horizons. It attracted a total of 9639 likes, comments, and shares.
The worldwide interest in physics evidenced by Physics Today's Facebook page came to me as a welcome surprise. I'm delighted that the page has, say, 21 553 fans in the country of Nepal or 12 661 fans in the city of Dhaka, Bangladesh. We even have fans in strife-torn Iraq and Syria.
The American Institute of Physics founded Physics Today in 1948 to unify a physics community that, in the words of the magazine's first editor-in-chief, David Katcher, had become compartmentalized into groups of specialists who identified with their fellow specialists and whose research had become opaque to outsiders.
Physics Today still serves that mission. And now, through its Facebook page and its fans' enthusiasm for physics, Physics Today is connecting people from different cultures and countries.