### The upside of procrastination

I've long wondered about the problem arising at the intersection of interstellar space travel and Moore's Law. Moore's Law is an empirical rule that states that technology doubles in speed (or other metric) every 18 months. The laptop that I'm typing this post on right now will be half as fast as the next Macbook Pro 18 months from now.

I doubt I'm the first person to think about this, but imagine a large crew of space settlers at the halfway point to alpha Cen. They might be the second or third generation aboard the space craft, having known nothing but their trip to the nearest stellar system. Out comes the bubbly, but in the middle of the celebration there's an announcement: "Captain, there's something showing up on our radar, approaching fast!" As the object flies by, the crew can just make out the relativistically shortened form of a brand-spanking-new, next-generation space craft, zipping past using the latest technology on the way to alpha Cen.

So if Moore's law guarantees that there will be a better, faster, more efficient space craft if you wait a couple decades, then you should wait for the new ship rather than starting the journey with today's technology. But there must be a break-even point. The solution to traveling to the next star over can't be to just sit around twiddling our collective thumbs. Right?
 Figure from Gottbrath et al. 1999

Well, it turns out that this problem has been solved back in 1999...by astronomers (PDF here). The specific problem in their cas was whether to start a long computation with today's computer, or instead wait until Moore's Law brings along a much faster machine.

Jason said…
It's been bugging me all week, but I finally found the examples of this I was searching for:

In the Marvels comic book Guardians of the Galaxy (coming soon to a theater near you) a human on the first interstellar mission arrives at Alpha Centauri after a thousand year sleep, only to be met with a hero's welcome by the centuries-old human civilization founded by subsequent generations' faster-than-light colony ships.

Steinn Sigurdsson comes through with the original version of this: "Far Centaurus", which Wikipedia explains this way:

Far Centaurus (1944), short story by A. E. van Vogt published in the collection Destination: Universe! (1952). A crew of Terran explorers who have been hibernating through a centuries-long voyage to Alpha Centauri discover on arrival that their technology has been radically superseded; humanity has arrived at the Alphan planet Pelham via superluminal travel long before them, and has long forgotten about them and their primitive mission (compare Comics: Guardians of the Galaxy below). The travelers must overcome their childlike naÃ¯vetÃ© to cope with the near Godlike human civilization that has evolved in their absence—a good example of the "quasimessianic ... transcendental omnipotence" with which van Vogt often furnishes his protagonists in order to generate a sense of wonder in his tales.[6]
Jason said…
More Far Centaurus:

http://www.centauri-dreams.org/?p=278

### On the Height of J.J. Barea

Dallas Mavericks point guard J.J. Barea standing between two very tall people (from: Picassa user photoasisphoto).

Congrats to the Dallas Mavericks, who beat the Miami Heat tonight in game six to win the NBA championship.

Okay, with that out of the way, just how tall is the busy-footed Maverick point guard J.J. Barea? He's listed as 6-foot on NBA.com, but no one, not even the sports casters, believes that he can possibly be that tall. He looks like a super-fast Hobbit out there. But could that just be relative scaling, with him standing next to a bunch of extremely tall people? People on Yahoo! Answers think so---I know because I've been Google searching "J.J. Barea Height" for the past 15 minutes.

So I decided to find a photo and settle the issue once and for all.

I then used the basketball as my metric. Wikipedia states that an NBA basketball is 29.5 inches in circumfe…

### The Long Con

Hiding in Plain Sight

ESPN has a series of sports documentaries called 30 For 30. One of my favorites is called Broke which is about how professional athletes often make tens of millions of dollars in their careers yet retire with nothing. One of the major "leaks" turns out to be con artists, who lure athletes into elaborate real estate schemes or business ventures. This naturally raises the question: In a tightly-knit social structure that is a sports team, how can con artists operate so effectively and extensively? The answer is quite simple: very few people taken in by con artists ever tell anyone what happened. Thus, con artists can operate out in the open with little fear of consequences because they are shielded by the collective silence of their victims.
I can empathize with this. I've lost money in two different con schemes. One was when I was in college, and I received a phone call that I had won an all-expenses-paid trip to the Bahamas. All I needed to do was p…

### The GRE: A test that fails

Every Fall seniors in the US take the Graduate Records Examination (GRE), and their scores are submitted along with their applications to grad school. Many professors, particularly those in physics departments, believe that the GRE is an important predictor of future success in grad school, and as a result many admissions committees employ score cutoffs in the early stages of their selection process. However, past and recent studies have shown that there is little correlation between GRE scores and future graduate school success.
The most recent study of this type was recently published in Nature Jobs. The authors, Casey Miller and Keivan Stassun show there are strong correlations between GRE scores and race/gender, with minorities and (US) white women scoring lower than their white male (US) counterparts. They conclude, "In simple terms, the GRE is a better indicator of sex and skin colour than of ability and ultimate success."
Here's the key figure from their article: