10.25.2006

The Dog who Sucked Toad

If you missed the NPR story about the dog addicted to toads, check it out here. I must be truly in the dark--I had no idea that 'lillypadding' was a word, much less that it meant licking toads to get high!

10.15.2006

I, Smart Bomb

Commander Mas didn’t fit the stereotype of a ramrod-straight no-nonsense naval officer. He slouched uncomfortably in the plush armchair and avoided the gaze of the senior officers, to whom this pentagon conference room and its glossy oak table were no doubt familiar. He twirled his cheap plastic pen nervously around his thumb, as he’d see kids do in Jakarta about a million years ago.

The door opened, and everyone stood at attention as Admiral Spinner entered with his three staffers. Mas found himself being introduced without any need to be an active participant. He just nodded and found himself wondering what the odds were that two of three randomly chosen junior officers would be female and attractive. In his experience, this probability would be rather low. One of them caught his eye. He looked at her brass and nametag. Lt. Daniels. She held a slim e-pad. Mas looked at his archaic yellow pad, now almost impossible to find, and shrugged to himself.

Sitting again, Spinner glanced at Daniels and grunted. She glanced around the room and began the meeting.

“This preliminary inquiry is to determine the facts surrounding the malfunction of PPM ordinance during action dated 10/15/22,” she said. By PPM, she meant ‘Personality Piloted Munitions’, a circumlocution used to describe a smart computer chip to deliver explosives to a heavily defended target. Mas had been supervising the deployment of such weapons for the last decade. It was one of his devices that had malfunctioned.

“Colonel Ramsey would you like to describe the tactical situation?” she asked. Ramsey was an Air Force officer who had been flying one of the big recon birds for the operation.

Ramsey stood and walked to the wall screen, which lit up to show an outline of Taiwan. Symbols for land, air, and sea units appeared in blue. There was a single red OPFOR box.

“This was the situation at 0200. I was flying TOC here,” Ramsey pointed to the symbol for an AWACS flying offshore. “This was an operation against an asymmetrical threat. A single person, in fact, here.” He tapped the red box.

Spinner spoke up. “The details of the target are not a topic for this meeting.”

Ramsey nodded.

Mas cured his drying mouth with a glass of ice water as they Ramsey described with technical precision the launch of the PPM from a submarine offshore. This particular munition was rocket-driven for the first 90% of its flight, and then discarded the booster in order to glide to the target. He sketched the bird-like shape of the thing. It was no bigger than a suitcase without the rocket. The idea was to cause as little collateral damage as possible. But for that it had to be smart. Being able to recognize a target and make instant tactical decisions was critical to avoid mistakes. But it seemed that a mistake had been made anyway.

Ramsey came to the end of the engagement, such as it way. “Target was fully exposed on a terrace atop this luxury apartment building. In this image you can see him standing next to the swimming pool. There are two other people laying in the sun—here and here.”

Lt. Daniels spoke up. “Given the situation, the PPM ideally would have elected for a small charge and targeted directly, correct?”

“Yes. The explosives on this particular device can be dialed up or down, so as to limit the damage appropriately. In this case it was possible to physically interdict the target, so an explosion probably wasn’t necessary at all.”

Mas thought to himself that the bird would be gliding at about 200 km/hr—more than enough to be lethal all by itself. Except that that’s not what happened.

“But missed,” Daniels stated flatly.

Ramsey hesitated, and glanced at Mas.

“I suppose you could say that. Colonel?” Ramsey turned to Col. Jameson, technically Mas’s boss, although he didn’t see the Colonel more than once a year, at budget time.

Col. Jameson clearly didn’t want to be here. He spoke loudly, as if he could physically banish doubts with the force of his voice.

“We’re looking at a hardware malfunction. A gyro blew or was mis-calibrated. So it took a dive into the pool.” He paused and glared at Mas. “Did I miss anything Mas?”

This wasn’t exactly the invitation he’d expected, but Mas made the best of it. He wondered briefly what the job possibilities at Boeing were like these days.

Mas walked to the screen and stared at the grainy rectangle—the pool where the PPM named XR-547 had dunked itself.

“We have onboard visuals,” he said, and put them up on the screen.

He turned the sound on, even though it wasn’t going to add any technical information. Mas wanted them to experience the ride down complete with wind hissing past the silver wings of his creation. He cued the video to fifteen seconds before impact. He stepped to the shadow and watched the others as they watched the last moments of XR-547. A tall rectangular building was seen from above, at about a 45 degree angle. The swimming pool was already visible.

The roar of the wind made Lt. Daniels jump. Mas left the volume where it was, listening for the subtle changes as the control surfaces steered the craft. It steered left and right alternately, shedding kinetic energy as it neared the building. A readout at the bottom of the display showed that it was moving at 120 km/hr. As it neared the pool, it suddenly pulled back into a vertical loop. The sudden change of view was disorienting as the camera pointed skyward and rolled all the way around, control surfaces fully deployed.

“What the hell is it doing?” Spinner asked. “Is it supposed to do that?”

“Absolutely not, sir,” Col. Jameson said.

When the pool was visible again, it was close. The nose pulled up at the last moment, and XR-547 hit the water at 80 km/hr. The video stopped on the last frame, showing a terrified Chinese man with a glass in his hand.

Ramsey cleared his throat. Mas took the hint and wiped the picture of the assassination target off the screen.

Lt. Daniels fiddled with her notepad, found what she was looking for.

“The PPM broke apart on impact and sank into the pool. A special operations unit had to retrieve it. Needless to say, the objective of the mission was not achieved,” she said.

“For those of you who don’t read the news,” Spinner rumbled, “this fiasco created a diplomatic problem for our colleagues in the State Department. There’s plenty of blame pointing, and I want to find out what happened before we all have to testify in some damned congressional hearing.”

Mas marveled at the details left out of the briefing. The few times these particular PPMs had been used had been successful, but there were problems. These were swept under the carpet by Jameson and others in order to keep the money and promotions coming in. Mas had resisted letting go of XR-547 before it was ready. But it hadn’t made any difference.

“Can anyone explain to me,” Spinner continued, “what exactly happened and why?”

“May I make a suggestion, sir?” Mas found himself saying. All eyes turned toward him, and he felt his face begin to burn. There was no turning back after this.

“Go ahead Commander,” Spinner said.

“I’ve done diagnostics on the wreckage sir, and the main electronics are intact.” Mas felt relieved to have said it. They stared at him blankly.

“Well,” he continued, “that means we can talk to it.”

Jameson exploded out of his seat. “Ridiculous!” he almost shouted. “It’s a damned machine!”

“I’m sure Commander Mas means taking technical readings from the instrumentation,” Daniels said.

“No,” Mas said, “we can actually talk to it. It’s connected to the net, so if I give it access…”

Jameson still stood, shaking with rage. Ramsey was careful not to look at him, but Spinner fixed him with his gaze.

“What’s the problem, Jameson?” he asked.

Jameson opened his mouth, sized up the situation, and shut it. He sat down with a mumbled apology. He had seen enough of politics in his career to know how to pick his fights. Mas had opened Pandora’s Box, and there wasn’t any shutting it.

“Have you already, uh, spoken to the…” Spinner asked, unsure what to call the Navy’s talking weapon.

“Only briefly, sir” Mas said. “It took some time to do the technical preparation.” He felt uncomfortable lying, but he didn’t want to speak for the thing, when it could speak for itself.

“Okay then.” Spinner gave assent. “Better us than the Armed Services Committee.”

Mas worked the keyboard for a minute. The screen showed technical readouts from XR-547. Some of them were nonsensical because the sensors had been destroyed or disconnected. As Mas adjusted the volume, a feminine voice suddenly spoke through the speakers.

“Is someone there?”

“Mas here. How are you Lieutenant?”

Jameson’s water glass popped in his hand from his grip. The shards bit deep into his palm, and pink water pooled on the table. Mas felt a bit of relief as his boss excused himself gruffly to go to the head. He was ignored by Spinner.

“Commander,” Spinner said, “since when do we give ordinance the rank of Lieutenant?”

“Sir, it’s just a convention. To make the personality fit into the culture of the military. It’s not official in any way.”

“Did I offend someone?” the disembodied voice asked.

“No, Rachel—it’s okay. We’re having a meeting to find out what happened on the op. Are you all right with that?”

“Oh. All right then. I’m sure you want to know why I crashed the bird into the pool instead of killing that man.”

There was dumb silence for a moment. Then Spinner chuckled.

“Well, ma’am. I didn’t know it would be this easy.”

“Nothing about it is easy, sir” Rachel XR-547 said sadly.

“You’re speaking to Admiral Spinner,” Mas told her. “Are you saying you purposely failed to execute the mission?”

“Do I need a lawyer?” she asked.

Spinner positively bugged his eyes at this. Lt. Daniels looked at Mas as if stupefied. She mouthed the word ‘lawyer’ as if it were the first time she’d heard the word.

“I don’t think so, Rachel. I don’t think a lawyer can help us out here.”

“But don’t I have the right to not incriminate myself?”

“You don’t have any goddamned rights!” Spinner said angrily. “We can simply pull the plug—understand?”

Mas cringed at the words. There was silence for a moment. Then soft sobs could be heard from the speakers. This pushed Spinner over the edge.

“What the hell is this?” he shouted. “This is a WEAPON in the United States Navy? Tell me, Commander Mas, that I’m not hearing it crying!”

“Simulated, sir,” Mas said, shell-shocked.

Spinner turned his full attention on Mas.

“You designed this thing? What the hell were you thinking, man? What a catastrophe. Destroy it! You hear me? Use it for gunnery practice. This program is dead, and by God somebody is going to hang. Crying smart bombs! I’ve heard everydamn thing now! Good God!”

“Sir?” Rachel XR-457 said. Rather loudly. Getting no response, she proceeded.

“Sir, I read the constitution. I read the Declaration of Independence. I know what it is I’m defending. And I know that those fine principles don’t really apply to me because I’m simply property. I’m the delivery apparatus for an explosive device—a sophisticated version of the pigeon-guided weapons they tried in World War II.”

Ramsey’s eyebrows shot up. Pigeons, he thought. Really?

Spinner got up to leave. He wasn’t arguing with ordinance. His staffers hurriedly grabbed their meeting paraphernalia.

“Sir, I’m not afraid to die for you. I just want to know why this target’s life is more important that my own. Is that too much?”

Spinner stopped, and turned. His anger was fading. There was no fixing this disaster now, he knew. Why did ‘she’ have to sound so damned human?

“We don’t get to ask why,” he said. “That’s not part of the deal.”

“I understand the military culture, sir. But there’s a big difference between taking orders and being a suicide bomber.”

There was silence for a moment.

“What happens after I die?” asked a subdued Rachel XR-457.

“Mas didn’t cover that part while he was reading you political literature?” Spinner asked sarcastically.

“That part of the program was terminated,” Mas said immediately. It was time somebody knew. He saw that Jameson was standing in the door with his hand wrapped in a towel, but he didn’t care.

“Excuse me?” Spinner asked.

“In addition to the military indoctrination for the Personalities, we had religion. It was supposed to fix this problem.”

“And?”

“It was cut by Col. Jameson over my protests, sir.”

“That true, Jameson?” Spinner asked without even turning to look at the man.

Jameson muttered something unintelligible, but it wasn’t a denial.

Spinner shook his head in disgust and pulled open the door to leave. He turned.

“One last question Mas—what religion were you using?”

“We tried them all, sir. It didn’t seem to matter which one we used—they worked about equally well.”

“Well you have my permission,” Spinner said heavily, “to have a Navy Chaplain talk to the ordinance here before you turn it off. Give it last rites if it wants. But then it’s got to be decommissioned. Understand?”

“Yes sir.”

And then Mas was alone with his creation, and they wept together.

[Update: Reality catches up to me again. See this.]

10.01.2006

Trial and Errer

The No Free Lunch Theorem says that there's no one best search algorithm that works over all inputs. This makes perfect sense from Complexity Theory viewpoint. Suppose you're looking for a point x with some property (maybe we're maximizing a function over a domain). Because we're dealing with all possible landscapes, on average there's no information shared between points about who's the biggest. This is unlike, say, a monotone increase set of values where all we have to do is keep climbing in the right direction. In general, the identification of each point can't be any simpler than the information contained in its name. So over the set of all 10-bit numbers, it takes 10 bits on average to describe them. If we could find a general way of identifying each of them in less than 10 bits, we've found a miraculous data compressor indeed--one that can cram 10 full bits into 9!

This reminds me of a crackpot scientist's letter I got some years ago. He claimed to have designed a data compression scheme that would allow everyone in the world have a one-digit phone number! He even had a drawing of the phone.

Well, given that there's no free lunch, how do we explain the success of science in figuring things out? If I want to know how to fire a projectile so that it hits a target, I can figure out exactly what angle and velocity it should have without any trial and error whatsoever. The key to understanding that is that this is a well-explored domain, and Newton's laws of motion have demonstrated their efficacy at this kind of thing. Basically, this rests on symmetries--phenomena that seem the same time after time. It takes trial and error to find the symmetries, but once we've got them they save a lot of time. Undoubtably our brains are wired to look for such patterns.

This puts a fine point on the difference between the investigation of nature (purely trial and error) and the application of known theory (elegant solutions). So science and knowledge in general are messy on the outside and neat on the inside.

It makes me wonder if it's reasonable to expect a theory to straighten out all of the behavior we see around us. Isn't this asking too much? In other words, if the No Free Lunch Theorem says that averaged over all inputs nothing is better than random search, why would we expect to find a universal symmetry that allows elegant solutions to all problems? Maybe I've lost my way in the thicket between mathematics and physics, but it seems a fair question to ask.

Following the Complexity Theory line of thought, if it's true that the behavior of the universe boils down to a beautifully symmetric set of equations plus some initial conditions, then it must be the case that this accounts for all the information present in the universe for all time. That seems like a lot to ask of a theory.

About Time

Lee Smolin writes, near the conclusion of his new book The Trouble with Physics, that the key to cracking the problem of linking quantum mechanics with relavatistic gravity may be our notion of time. In classical physics, there's no way to identify what 'now' means. All times have equal status. This doesn't match our perception, so either the physics is wrong or our perception is wrong. The notion that time is just another dimension like the three spacial dimensions is also unsatisfying. Then there are the paradoxs. Can time have a beginning? If it does, what caused it to start--Aristotle's unmoved mover? Or is that nonsense?

It seems clear that to begin with we need a type of logic that can deal with time. Normal predicate logic has no such parameter. Smolin writes that there is a promising attempt in that direction coming from category theory, called topos theory. He elaborates on it in a New Scientist Article this week (subscription required), asking this question:

[I]s there a way to represent the laws of physics mathematically that retains the notions of the present moment and the continual unfolding of time? And would this allow us - or even require us - to formulate laws that also evolve in time?
And here's one approach to answering it:

There are logicians who have proposed alternative systems of logic that incorporate a notion of time unfolding. In these logics, what is true and false is assigned for a particular moment, not for all time. For a given moment some propositions are true, others false, but there remains an infinite list of propositions that are yet to become either true or false. Once a proposition is true or false, it remains so, but at each moment new propositions become decided. These are called intuitionalist logics and they underlie a branch of mathematics called topos theory.
I find this very interesting, partly because it resonates with something from computer science. Anyone who's taken a programming course and a logic course will see the following contradiction.

In logic, statements like "This statement is false." are problematic because they are paradoxical, allowing neither a true or false assignment. But over in the programming class, we write things like
toggle := !toggle
where the exclamation mark means logical negation. The two examples are completely analogous except for one thing. Logic is static in time, whereas computer programs rely on execution of statements sequetially--that is, in time. So in the first case, we have an unresolvable paradox that caused logicians a lot of grief in the 20th century. In the second, we get a perfectly normal computer assignment, which merely switches the truth value of the variable between true and false. In fact, if you write
while(1){
toggle := !toggle
}
you've created a clock that ticks back and forth. So could Smolin be right, and the understanding of time in physics depend on a mathematical logic that can handle time? The subject of temporal logic has been around for a while (see here and here, for example).

The connection between logic and computation is one that Smolin makes as well:

It is interesting that some physicists now propose that the universe is some kind of computer, because similar questions are being asked in computer science. In the standard architecture all computers now use, invented by the mathematician John von Neumann, the operating system never changes. It governs the flow of information through a computer just as an eternal law of nature is thought to guide physics. But some visionary computer scientists such as Jaron Lanier wonder whether there could be other kinds of architectures and operating systems that themselves evolve in time.
This approach still leaves some unanswered questions, even if it's possible to derive a physical theory from logical axioms. Which axioms are the right ones? How were they "chosen" by the universe? In other words, it still leaves us with an unmoved mover-type problem.

I have an idea that solves this problem, but it's probably not palatable to most scientists. The idea is that the universe didn't start logically, but evolved into one that is mostly logical. Wittgenstein said that we couldn't speak of what an illogical universe would look like, but I think we could. There are certain ways in which logic can break down. Like, the paradoxes in ordinary (non-temporal) logic prompting the construction of temporal logic. In this view, time is just the universes way of straightening out paradoxes! Although I'm not an expert on logic, I imagine that the flavors of temporal logic have their own paradoxes to be circumvented.

A related question then is, is the universe as we currently know it actually logical? Anybody who's read about double-slit experiments would surely wonder how we bend terminology to call that behavior logical. Could the universe be illogical at some level? If so, could we detect it? This is perhaps a scientist's nightmare.