All posts by Ben


I’m in Prague! For the first three or four days I was just around the conference hotel, which is nice but not especially Czech. But then last night I walked around Real Old Prague.


It’s … I have no knowledge of Prague or Czechia, no associations or cultural connection. All I can do is sort of boggle, and compare it to places I’ve been before. It feels kind of like the old sections of Paris but … bigger? Wider streets, bigger plazas. Maybe it’s actually not that old, just built in a very beautiful old style?

I really know nothing, but it’s pretty! And full of tourists, but I can’t very well complain about that.

Is Biology the only Von Neumann machine?

People have been talking more lately about Moon Bases. Maybe it’s because of the world’s most expensive luxury cruise, or the Google Lunar X Prize, or Newt Gingrich, or Japan. Doesn’t matter.

If you want a moon base, you probably want to build it before anyone has to live there. This creates a double bind: who builds the moon base? Someone has to show up and start shoveling, and then there’s nowhere to sleep.

What would really be great is if we could send some robots up there to build a moon base for us. Then it would be comfy when we arrive. No shoveling required.

Of course, we’re probably talking about robotic bulldozers and such, heavy stuff to launch into space. And they only work so fast; it might take a long time. We might have to send a lot of them if we wanted, say, a city on the moon, and then we’d have to keep sending them from earth when they broke down. Annoying.

What would really be nice is if we could just send up one of these things, and then tell it to build another one. You know, melt some regolith, refine some metals, grow some silicon crystals, carve out all the parts, stick them together. Now you have two lunar construction robots. Do that a few times and you could really build something big, fast.

This notion is called a Von Neumann probe, after John Von Neumann, who first considered this kind of machine in an abstract way, shortly before computers and space probes started to become real things.

Von Neumann machines, or self-replicating machines, have a remarkable property: in a convenient environment, their numbers can grow exponentially. That can be very convenient for, say, colonizing an inhospitable planet. They also have a big problem: no one’s ever figured out how to build one.

It’s easy to see why it might be hard to build such a thing. Say you start with a bulldozer. Maybe you have a plan to use computer controls to carve molds out of sand and then fill them with molten iron, which will become parts for the new bulldozer. Great. (Drexler would call this a clanking replicator.)

This process is going to be complex, so you’ll need a pretty sophisticated digital logic system to drive it — a computer, essentially. But how are you going to make a computer? Current computers are made out of silicon doped with phosphorus and boron, so you’ll have to find those elements and purify them, a step which requires additional equipment that you’ll also have to carry around. Then there’s the lithography step, which currently requires a gigantic clean-room, an army of solid-state quantum physicists, and a bunch of very carefully tuned machinery that is nigh-impossible to build.

You have to carry all of this with you, and all the equipment required to build it, and all the equipment required to build that equipment … one might wonder whether any finite-size machine can actually achieve this.

Shortly after Von Neumann wrote his mathematical treatment of this idea, showing that it was possible in principle, in a bare mathematical sense, Watson and Crick published their analysis of DNA. Within a few years, it was clear enough: Von Neumann machines really are possible, because every living creature is a Von Neumann machine.

We can start from the simplest cell. A cell consists of (1) a DNA strand encoding some information, (2) a cell membrane (made of lecithin) and (3) some other stuff like ribosomes and RNA polymerase for reading the DNA. It’s abundantly clear that this thing is a self-replicating machine. If you don’t believe me, just watch The Inner Life of the Cell.

How does the cell avoid the limitless expansion of required equipment? I like to think that it relies on the discreteness of matter. Rather than build at macroscopic scale, out of chunks of solid stuff, cells are built atom-by-atom by ultra-miniaturized construction equipment. The simplest cells start to look distinctly digital, with countable numbers of atomic-level components that can be copied or deleted as needed. The problem becomes discrete instead of continuous, and therefore finite instead of infinite.

It’s really cool.

This seems like good news for Von Neumann machine enthusiasts. We know there’s at least one kind, so maybe there are more! But are there?

The thing about Von Neumann machines is that they copy themselves, which means pretty soon you have a lot of them. On earth, we see them everywhere, and typically refer to them by subtypes, like trees, people, mildew, etc.

But we only see one kind. All of these things are Life, which is just one kind of machine. They all have the same lecithin-based membranes, and DNA-based memory units, and closely related other machinery. They all formed from a single family tree.

When we look in rocks, we don’t see little rock-machines tunneling around making copies of themselves. There are no ice-robots, magma-swimmers, solar jellyfish, or moon men. We would know if there were, because once these things get going, they don’t stop until they run out of stuff, and then they start fighting for the remaining stuff, eating each other, diversifying into predator and prey, etc.

Instead, all we see is silence.

Life as we know it formed less than a billion years after the Earth itself, and maybe a lot faster than that. The universe has been around for 13 billion years, and there are countless billions of planets and stars. Where are all the strange self-replicating things? (This is a variant of the Fermi Paradox.)

I think we should entertain a possible answer: they’re here, and we’re it. We have exactly one known type of Von Neumann Machine, and some good reason to believe that if others were possible, we would be able to spot them. We also know that all the other types we’ve tried to design have some serious problems that smell like fundamental physics.

So maybe, just maybe, the laws of physics only permit one kind of self-replicating machine, and it loves cake and hates bleach. Or to be more precise, maybe the space of physically allowed self-replicating machines is connected and fundamentally resembles Biology.

If so, scifi fans are in luck: to learn much about the universe, we really will have to build spaceships, and colonies, and all the rest. The robots won’t get to have all the fun.

The Three Musketeers

The Hudson Warehouse theater company is doing their amazing annual thing: free performances in Riverside Park all summer long. Two years ago we saw their She Stoops to Conquer; today we saw an original production of The Three Musketeers.

Some details of the plot have been excised, and perhaps slightly altered, but the main points and favorite scenes are all there, in full swashbuckling glory. The script is interesting, mixing archaic English (and a light sprinkling of French) with modern colloquialisms and the occasional anachronistic cultural reference. One character, ostensibly listing the desirable traits for a Musketeer, actually recites the (American) Boy Scout Motto.

Mostly, though, the play is an excuse for sword fights. We showed up an hour early to claim front row seats, and watched the final rehearsals of every fight, first slow, then full-speed. Some sequences (like a match between a rapier and a beer stein) took several rounds to polish, but in the performance somehow everything worked.

The actors were unamplified, performing in the open air, in a space not designed for acoustics. It’s a quiet park by New York City standards, but still a tremendous challenge to project to the back of the house. The actors more or less yelled their lines, which sounded natural in some voices and strained in others. Amplification might have helped, but seeing as the actors performed straight through a light shower, I can see why they avoided it.

All in all, I’m definitely a fan of Hudson Warehouse. They don’t take themselves too seriously, and neither did these authors and playwrights.


We live about 4 (long) blocks from Bryant Park, which shows classic movies in the summer. Last night they set up the screen, not to show some old movie, but to present a brand new TV show. It was the open-air premiere of TNT’s Will a tale of the young William Shakespeare, trying to make a career for himself.

In my view it’s … flawed.

  • It’s drenched in graphic violence, gore, and as much sex and nudity as one can get away with on network TV.
  • The costuming is so excited that it breaks any suspension of disbelief.
    The Globe’s groundlings wear clothes, makeup, and hairstyles that look more like an EDM show than Elizabethan England. At one point a major character shows up in a leopard-print bomber jacket … no.
  • Rather than struggling for his craft, apprenticing, working odd jobs and trying to get his foot in the door, Will is an impossible overnight success. Literally: he produces a full play at the Globe on his second day in London.
  • The cinematography is bizarre. At one point the frame rate drops to like 2 FPS, in a clumsy attempt to convey disorientation or something. Don’t mess with the frame rate! You’re just reminding everyone that this is a video!

It’s still interesting, though. The plot is built on the presumption that Shakespeare is a crypto-Catholic, fleeing persecution by the theocratic state. It’s a conceit used to draw parallels to persecution in our own time … mostly ham-handed, but sometimes effective.

There’s also a pretty fun Elizabethan rap battle (a “duel” of words). That’s a testament to the acting, which is pretty much uniformly great.

I don’t think I’m likely to watch the rest, not least because I don’t have a TV subscription, but I hope the show works for someone out there.


This weekend we went to a lovely wedding in the Poconos, and that meant renting a car. Everything went smoothly, even our complicated double-one-way rental arbitrage, until I tried to return the car in New York today to the Enterprise on 53rd between 5th and 6th.

It turns out that 5th Avenue was closed for the Puerto Rico Day Parade … and 53rd runs Westbound. Topologically, it was not possible to access the rental car agency.

I eventually developed a stratagem: drive all the way around the parade, then come at 6th south of 53rd, then drive up 6th, meet the officer stationed on that corner, and explain the problem to them.

It took a heck of a long time, driving through worst case scenario traffic, to make that first loop, and then it still didn’t work. Every time I tried to turn onto 6th, police were forcing everyone to go straight, no turns allowed. I have no idea why; cars were driving down 6th like No Big Deal.

On my fourth or fifth attempt, I finally managed to turn onto 6th … only to discover that 53rd had been opened, and was full of traffic. I would have to come at it from the East, assuming that they would let me make the turns required to get there. Luckily, on 54th I spotted an unlisted back entrance to the rental car agency. Thank goodness.

The whole business took 2.5 hours, during which time I subsisted on white fudge pretzels and Starburst … and drove less than 10 miles.


On Friday night, we went to Central Park at dusk to watch a showing of Potiche, part of the French Embassy’s enormously successful programme of free French movies outdoors in New York.

It’s a perfect 70s French comedy, about an aristocratic grandmother, stuck in an unfaithful and unhappy marriage, who through luck and pluck is transformed, first into a successful CEO, and then into a popular politician. Along the way her facade of conformity falls away, revealing unexpected aspects of her character.

It works incredibly well, and also feels shockingly modern. I remarked afterward how amazing, that a movie from that era could take such a critical, feminist, yet lighthearted approach.

My friends explained to me that it was released in 2010, not 1978.

Maybe I’m just not very bright. In retrospect, when Suzanne said “I’m a woman of the 80s … I’m ahead of my time”, and everyone laughed, that could have been a clue. On the other hand, maybe a lot of the cues we use to date films are in the jargon, even the accent. (The Cafe Society, Woody Allen’s recent film set in 1930s Hollywood, was notable for its strictly modern dialog.) Not speaking a word of French, I had no idea. I also don’t know any French actors, so I couldn’t use their ages to gauge.

Anyway, bravo to the cinematographers, hair, makeup, costume, and set designers of Potiche, for their convincing illusion.

Hayesy Sunday

Back in Seattle, living alone with a huge TV set, I used to watch a lot of Rachel Maddow on MSNBC. At that time, the show was dominated by the phrase “traffic problems on the George Washington Bridge”.

Oh, how the worm turns.

When Maddow was unavailable, Chris Hayes would sub in. They seemed to be cut from the same cloth: liberal commentators with an engaging, academic lecturing style and an emphasis on history and colorful anecdotes.

On Sunday, Hayes spoke at Lehman College, a CUNY site in the Bronx, and I went to listen, along with a few hundred white liberal retirees and younger Bronx locals. It was more or less part of a book tour for A Colony in a Nation, Hayes’s new book.

I haven’t read the book, but the notion seems to be that for some people — basically non-whites — their daily experience is more like living in a colony governed by a foreign power than it is like living in a self-governing democracy. It’s an interesting “frame”, a “theory” only in the philosopher’s sense. It isn’t a prescription, or even a prediction, just a metaphor supported by remarkable stories from American history.

Hayes suggested that curious audience members seek out a few video clips, which he didn’t show. One was Ronald Reagan’s 1980 visit to the South Bronx, in an area which looks more like a devastated third-world country than part of a major US city. Reagan promised to restore jobs to these blighted areas. Instead, the Reagan administration funded a city program that covered some of the broken windows in the area with decals of lovely interiors.

Hayes, a famous rich white man with a white TV audience, is perhaps not the ideal messenger for a reminder about the mistreatment of poor minorities in the US, and the prioritization of white Americans’ needs, but it turns out he’s also a Bronx native. He’s also just as eloquent in person as on his TV show.

I enjoyed the speech, a welcome reminder about the depth of the disparity between communities, deepened by overly white police forces that are accountable to the fearful voting public, not the neighborhoods they patrol. I was intrigued by his analysis of Donald Trump, who came of age at the peak of New York’s racially tinged crime wave, and now projects the dysfunction of that era out to the country at large. I even liked his distinction between policing philosophies that focus on reducing violent crime and “maintaining order”.

Sometimes I get annoyed at writers who jump to solutions, as if each problem in the world has a two sentence solution. (The Economist is particularly bad.) But after an hour soaking in the significance of the problem, some ideas on how to address it would have been a nice touch.

P.S. One other funny thing about this event was the audience’s inability, implicit in the questions they asked, to distinguish Chris Hayes and MSNBC from the Democratic Party, and especially the Bernie Sanders wing. The media’s polite veil of impartiality seems to be lost on their audience.

Green Morning

I grew up listening to Green Day. Dookie, their breakout album, was the second CD I ever owned, and I’ve more or less memorized every track, plus probably one song off of every album since, which is getting to be a lot. I could fairly be called a fan.

So it came to pass that this morning we woke up at 5 AM, put on our best punk rock* outfits, and skedaddled through Central Park to the line for … Good Morning America?

It turns out that NBC’s milquetoast morning show kills time on summer Fridays with about three songs from a different famous band each week. They could just have them in the studio, but instead they set up a stage in Central Park, and invite anyone sufficiently motivated to show up in person, for free. (Also, they like to use shots of the crowd in the live feed to convey excitement that might otherwise be lost on their heavy-lidded, bagel-focused audience.)

It was … odd. The gates opened at 7, but the show didn’t actually start until 8:30. In the mean time, there was a sound check, which looked like this. We sat on bleachers in the back, rather than stand amid the throng for two hours. This also gave us a great view of the white studio chairs where David Hasselhoff was interviewed by the anchors with hair and teeth from a bleach commercial. They smiled their wide-open laughing smile when the cameras ran, then switched to the steely expression of someone who beat 10,000 other people to get that job.

To fill time, they had a comedian chatting up the crowd, telling them when to cheer, hauling little kids on stage to sing Green Day, etc.. Then at 8:30, it was showtime.

Green Day were clearly pros. They’ve been doing this for 30 years, and still sounded great, although it’s hard to hit those high notes early in the morning, and the vocals were a little low in the mix. Still, it was odd. At a normal concert, the band might say something to the audience between songs. At this show, the band was mute, taking cues from the stage manager.

They sang three three-minute songs in half an hour, and then two more after GMA ended. We got on the subway and went to work.

They didn’t play American Idiot.

So I saw Green Day live, probably from better seats than I’d ever buy at a stadium concert, for free … but I wasn’t really the audience. I was just part of the wallpaper. The audience was in their breakfast nooks and airport lounges, listening to advertisements for white bread and stories about kids these days using their computers too much.

*Adult alternative, if you ask me.


We saw Beauty and the Beast at the upscale iPic theater, on a chaise for two that was almost right up against the screen. We could see the pixels.

After a while, though, you don’t see the pixels. You see technicolor visuals, watch beautiful but still slightly cartoonish CGI fall in love, and listen to the best (only?) ever bass aria from a Disney musical.

I do think I could improve it by excising the new pop-psych backstory that explains each character’s nature: Gaston has PTSD from The War; the Beast had no female role model, Belle is fighting gender stereotypes to become a woman engineer!

Also, surrealist Busby Berkeley numbers in CGI can really put your suspension of disbelief to the test.