# Odd Temporal Milestones

The first Star Trek episode aired closer in time to the ratification of the 19th Amendment—guaranteeing women in the US the right to vote—than to today.

# A morbid Python script

Comics #493 and #893 involve actuarial tables, which are tables for calculating the probability that someone of a given age will die within a given amount of time.

One evening, when I was feeling morbid, I wrote a Python script to calculate death probabilities for any collection of people: actuary.py (.txt). It takes a list of ages and genders and produces various statistics. Here’s the report for the nine living people who have walked on the moon:

```~\$ python actuary.py 81m 82m 80m 81m 80m 81m 76m 78m 77m
There is a 5% chance of someone dying within 0.08 years (by 2012).
There is a 50% chance of someone dying within 1.1 years (by 2013).
There is a 95% chance of someone dying within 4.08 years (by 2016).

There is a 5% chance of everyone dying within 10.78 years (by 2023).
There is a 50% chance of everyone dying within 16.12 years (by 2028).
There is a 95% chance of everyone dying within 22.57 years (by 2035).

Probability of all dying in 1.0 year: <0.001%
Probability of a death within 1.0 year: 46.32%```

And here’s the table for four of the main stars of the original Star Wars (Harrison Ford, Carrie Fisher, Mark Hammill, James Earl Jones):

```~\$ python actuary.py 69m 55f 60m 81m 10
There is a 5%  chance of someone dying within 0.42 years (by 2012).
There is a 50% chance of someone dying within 4.74 years (by 2017).
There is a 95% chance of someone dying within 12.83 years (by 2025).

There is a 5%  chance of everyone dying within 18.17 years (by 2030).
There is a 50% chance of everyone dying within 31.28 years (by 2043).
There is a 95% chance of everyone dying within 42.62 years (by 2055).

Probability of all dying in 10.0 years:   0.272%
Probability of a death within 10.0 years: 85.94%```

Of course, these are based on average death rates based only on age and gender. Adding more specific information about the people in question will refine the calculation. For example, I’d guess former astronauts are more likely to be in good health—and have longer life expectancies—than the rest of us.

# Groundhog Day correction

A number of people have mentioned an issue with today’s comic—in the movie Groundhog Day, it’s actually implied that Phil, Bill Murray’s character, didn’t have sex with Rita. He took her home to his room, but they woke up in the same clothes they fell asleep in. I haven’t seen the movie in a number of years, but I think they’re right—and bit of Googling suggests that I’m not the only one who was confused on that point.

Groundhog Day is, like Office Space, a comedy containing a gimmick that really sticks with you, even as the rest of the story fades. Or, at least, it did with me—I’ve probably seen the movie a couple of times, but I think I’ve spent a lot more time dwelling on the time loop scenario it describes. Now that people have raised the question, I’m not even sure that I interpreted the scene this way when I was watching it.

From a sci-fi point of view, the whole idea that the time loop was broken by emotional/personal development seemed kind of cheesy, but I just chalked that up to one of those things movies do because that’s how we like stories to work. Nobody wants a movie where the climax consists of an hour of excitedly inferring and testing revisions to the standard model of physics. (Or, at least, there aren’t enough of us to support a big-budget movie.) So while drawing my comic, I remembered that the time loop ended after he took Rita back to his room, and I filled in the typical romanticized Sleeping Beauty idea that I assumed had gone with it.

I appreciate the corrections—in addition to being a reminder to double-check pop culture references, it’s driven home for me what a neat, original movie Groundhog Day really is.

And now I wonder what kind of misconceptions I have about Ghostbusters.

# I’m visiting CNU on April 4th

I’ll be in Newport News, Virginia this April 4th to give a talk at my old school, Christopher Newport University.

I’m really looking forward to it! The chaos of the past year and a half didn’t leave me with much time or energy for travel or events, so it’ll be fun to get out and meet people again. I’m also looking forward to seeing the campus, which I hear has changed substantially since I left.

The talk isn’t limited to CNU students, so if you live nearby, you’re welcome to come! Admission is free, but since space is limited, you’ll need to reserve tickets here.

Hope to see you there!

# Geohashing

Almost four years ago, I posted a comic laying out the Geohashing algorithm. The algorithm generated a set of random latitudes and longitudes each day, spread out across the globe so there was generally always one within a few dozen miles of every location. I figured they could be used for hiking destinations, sightseeing, meetups, or whatever else people came up with.

I wanted to make an algorithm that anyone could implement, which didn’t rely on a central authority or ongoing support from any one maintainer. I also wanted to make it impossible to know the locations more than a day or so in advance, so that if geohashing became popular in an area, no one could publish a list of future locations that woud give property owners, park rangers, or local police time to prepare. So each day’s coordinates are randomized using the most recent Dow Jones opening price, which isn’t known until the morning of that day—or, in the case of weekends, a day or two in advance, which helps with planning larger weekend trips.

In the days after I posted the comic, there was a flurry of geohashing activity, which quieted down as the initial novelty wore off. But it didn’t die, and for the past several years there’s been a small but vibrant community building around the Geohashing Wiki. There are numerous daily expeditions, and they’ve taken some beautiful pictures and come up with a lot of neat tools, games, and achievements.

One of the many things they did was use a tweaked version of the algorithm to come up with a globalhash, a single coordinate for the day somewhere on the planet (biased toward the areas near the poles). They’re usually over the ocean, but a few of the land ones have been reached.

Yesterday’s globalhash fell less than a kilometer from the South Pole. User Carl-Johan got in touch with the Scott-Amundsen research station, and later that day, the hash was reached by Katie Hess, Dale Mole, and Joselyn Fenstermacher of the US, Robert Schwarz of Germany, and Sven Lidström of Sweden.

Wow. Just wow. Congratulations.

If you want to look up today’s geohash for your location, you can use this online tool, or one of the others listed on the Coordinate Calculators page.

# Tsunami photos and videos

In xkcd.com/1010 (I have a hard time not reading that as “ten”) I said that before 2004, there weren’t really any photos or videos of tsunamis. This isn’t quite true—there were a handful of photos and at least one video.

When I was a kid, I was had an irrationally powerful fear of tsunamis (Etymology-Man would suggest “cymophobia”). I swam in the ocean a lot when I was very young, so waves were a big part of my world.  I would fret about tsunamis whenever I was near the coast, and to this day I have occasional nightmares about a wave coming out of nowhere and sweeping me away.

Looking back, part of what made tsunamis frightening was was that I didn’t know what they looked like, and my imagination ran wild filling in the gaps. I read what I could find about them. In particular, I remember being just old enough to work my way through this book, and carrying it around with me so I could read the tsunami section over and over. It included a grainy photo of a ship in a Japanese harbor plowing through an unimpressive-looking line of breakers. I think that’s also where I found a photo of some people running away from something (it was this photo, but the reproduction in my book was too grainy to see what they were running from).

Years later, after the rise of the web, I realized maybe I could now find a video of a tsunami, and finally see the thing that had so captivated me as a child. But my searches for videos didn’t turn up much of anything.

Then the 2004 tsunami happened. Shortly after, as YouTube and its various clones proliferated, there was more horrifying footage available than I could handle.

A year or two ago, I read an article somewhere (I have tried to find it again with no luck) which mentioned that before 2004, there hadn’t been much in the way of photographic or video records of tsunamis, and that this had contributed to a lack of understanding of their form. My childhood impression seemingly confirmed, I worked this into a comic.

It turns out I was mistaken. There are several photographs, some of which can be seen here, here, and here. There’s also a video here (sent in by Phil Plait).

I think what confused me as a child was that none of the photos showed the wave I expected—just debris, and occasionally some visible water. Now that I’ve seen horrifying videos like this, I’ve gone back to some of those old photos and realized that they did show a tsunami. It was just so unlike what I was expecting that I didn’t recognize it.

So thank you to everyone who sent in information. It’s really fascinating stuff. Oh, and anyone interested in the history of tsunamis might want to check out a Google Books advanced search for material published before 1850 containing phrases like earthquake waveearthquake tide, or earthquake water feet. There are some gripping historical accounts buried there, along with some really interesting speculation by 19th-century scientists about the mechanisms behind earthquakes and their associated waves (the consensus seemed to be hot gas moving between subterranean chambers).

xkcd.com is registered with GoDaddy. This is an artifact of my registering my own domains nearly ten years ago, back when I was completely new to making websites.

I’ve always been a little uneasy about having all my domains with them, since they’ve got a long history of screwing over domain owners, but never got around to doing anything about it. A little while back, as the SOPA thing blew up, I poked davean, the xkcd sysadmin, about whether it was time to make switching to someone more geek-friendly a priority.

He’s also wanted to switch away from GoDaddy for years (and recently met with the reddit folks to chat about SOPA stuff). He’s periodically done surveys of the alternatives, but—strange as it sounds—he’s actually had trouble finding an affordable registrar with the feature set we needed. In particular, he said he had trouble finding any that support IPv6 Glue and DNSSEC via a control system that doesn’t rely on filing and waiting on support tickets, which he says (and I quote) “freaks me out” as a means of handling registrar stuff (he’s very much an xkcd.com/705 style of administrator). The ones that did offer those features tended to be a little too high-priced for our large number of domains.

We’ve had a number of alternatives recommended in the past week or two, but none have quite satisfied davean’s criteria. If you know of any registrars that might work for us, you can email us at contact@xkcd.com and he’ll take a look.

We’re being cautious about how we handle this switch, since GoDaddy has seemingly been obstructing transfers in a way that can leave the sites trapped in limbo. But don’t worry—it’s in the works!

# Money chart

I had a huge amount of fun putting the money chart together. It was the first time in a long time that my life’s been stable enough that I’ve been able to really disappear into a project—I’d almost forgotten how enjoyable it can be.

I’ve corrected a bunch of typos and other minor errors, most of which crept into the project during the final 36-hour no-sleep marathon to integrate all the pieces together. (Those corrections, plus a few more that will be added over the next few days, will all be integrated into the printed version).

Now it’s time for me to to spend some time relaxing with family, and trying to break the habit—trained into me by the research I did for the chart—of thinking of everything in economic terms. To those of you in the US (GDP: \$15.18 trillion[1], total net worth: \$58.73 trillion[2]), have a happy Thanksgiving!

After a rough year, it’s nice to have something happy to share.

We got married!

# For the handful of hurricane geeks out there

Selections from lost NHC discussion bulletins:

```HURRICANE HUMBERTO DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 500 AM EDT THU SEP 13 2007```

```THE NATIONAL HURRICANE CENTER HAS DETERMINED...BASED ON RECON AND MODEL GUIDANCE...THAT "HUMBERTO" IS A RIDICULOUS NAME FOR A HURRICANE. THIS WILL BE THE LAST ADVISORY ISSUED CONCERNING THIS STORM...UNTIL A MORE SERIOUS NAME IS CHOSEN.```

`\$\$ FORECASTER BLYTHE`

```HURRICANE FABIAN DISCUSSION NUMBER 15 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT SUN AUG 31 2003```

```FORECASTER AVILA CONTINUES TO INSIST...DESPITE ALL RECON EVIDENCE...THAT IT WAS NOT HE WHO TOOK MY SANDWICH FROM THE NHC FRIDGE. THIS ASSERTION IS NOT SUPPORTED BY FORECASTER STEWART OR MY STATISTICAL MODELS...AND BASED ON THE TIGHT CLUSTERING OF GUIDANCE...I AM ISSUING A WARNING FOR FORECASTER AVILA...THAT HE HAD BETTER BRING HIS OWN LUNCH TOMORROW. THIS WILL BE THE LAST WARNING ISSUED FOR FORECASTER AVILA.```

`\$\$ FORECASTER JACOBS`

```HURRICANE JEANNE DISCUSSION NUMBER 5 NATIONAL WEATHER SERVICE MIAMI FL 5 PM EDT TUE SEP 22 1998```

```THIS IS JUST TO SAY...THAT THE STORM IN THE ATLANTIC...WHICH WE NAMED JEANNE...IS STRENGTHENING. IT HAS A DISTINCT EYE... LIKE A WOMAN...AND GOOD PRESENTATION ON RADAR. THIS IS ALSO TO SAY...THAT ADVISORIES MAY BE ISSUED FOR BERMUDA...WHERE A DRYING FISH...RESTS ON A BEACH...BESIDE THE COCONUT PALMS.```

`\$\$ FORECASTER CARLOS WILLIAMS`

```TROPICAL DEPRESSION IVAN DISCUSSION NUMBER 59 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 11 PM EDT THU SEP 16 2004```

```THE LOW LEVEL CENTER OF CIRCULATION OF TROPICAL DEPRESSION IVAN COULD NOT BE LOCATED BY RECON...AND THE PRESENTATION IS POOR TO ABSENT ON SATELLITE IMAGERY. IT SEEMS SAFE TO ASSUME THAT...BARRING RENEWED CONVECTION ...THE CYCLONE HAS DISSAP-- ...OH GOD...HE IS HERE...IVAN IS HERE IN THE OFFICE...EVERYONE GET DOWN OH GOD HE IS INTENSIFYLKSDJFLKHHALKJKL...```

`\$\$ FORECASTER PRESCOTT`

```HURRICANE LILI DISCUSSION NUMBER 49 NATIONAL WEATHER SERVICE MIAMI FL 11 AM EDT THU OCT 03 2002```

```HEY GUYS...I WAS JUST WONDERING...IF YOU EVER THINK ABOUT THINGS. LIKE...YOU KNOW...WHETHER IT IS ALL WORTH IT.```

`\$\$ FORECASTER FREDERICK`

```TROPICAL STORM KATRINA DISCUSSION NUMBER 30 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT TUE AUG 30 2005```

``` THE WMO HAS DETERMINED THAT...DUE TO THE EXTREME DESTRUCTION CAUSED BY THIS HURRICANE...THE NAME "NEW ORLEANS" WILL BE REMOVED FROM THE LIST OF CITY NAMES...AND NOT USED FOR ANY FUTURE AMERICAN CITY.```

`\$\$ FORECASTER SCHOEN`

```HURRICANE ISIDORE DISCUSSION NUMBER 24 NATIONAL WEATHER SERVICE MIAMI FL 11 PM EDT SAT SEP 21 2002```

```HURRICANE ISIDORE CONTINUES TO STRENGTHEN...AND MOVE TOWARD THE BAY OF CAMPECHE. HOWEVER...THE NHC WOULD LIKE TO REMIND EVERYONE IN THE AFFECTED AREA THAT THE REAL STORM...IS INSIDE US ALL.```

` \$\$ FORECASTER ANDERSON`

` `