Monday, December 04, 2023

Lessons in Autonomous Weapons from the Iraq War

Read a good article this AM from the Brookings Institution from back in 2022, about issues in the use of automation in weapons systems: Understanding the errors introduced by military AI applications  [Kelsey Atherton, Brookings Institution, 2022-05-06]. It's in part a case study of a shoot down of an allied aircraft by a ground-to-air missile system operating autonomously during the Iraq War. That conflict predates the development of Generative Pre-trained Transformer (GPT) algorithms. But there's a lot here that is applicable to the current discussion about the application of GPTs to autonomous weapons systems. I found three things of special note.

First, it's an example of the "Swiss cheese" model of system failures, in that multiple mechanisms that could have prevented this friendly fire accident all failed or were not present.

Second, the article cites the lack of realistic and accurate training data, not in this case for a GPT, but for testing and verification of the missile systems during its development.

Third, it cites a study that found that even when there is a human-in-the-loop, humans aren't very good at choosing to override an autonomous system.

I consider the use of full automation in weapons systems to be - unfortunately - inevitable. Part of that is a Game Theory argument: if your adversary uses autonomous weapons, you must do so as well, or you stand to be at a serious disadvantage on the battlefield. But in the specific case of incoming short-range ballistic missiles, the time intervals involved may be too short to permit humans to evaluate the data and make and execute a decision. Also, in the case in which the ballistic missile is targeted at the ground-to-air missile system itself, if the intercepting missile misses the incoming missile, the stakes of the failure are lower if the ground-to-air missile system is itself unmanned.

It was an interesting ten pages that were well worth my time.

Saturday, December 02, 2023

Time, Gravity, and the God Dial

Disclaimer: my knowledge of physics is at best at a dilettante level, even with more than a year of the topic in college, one elective course of which got me one of the only two B letter grades of both of my degrees. (Statistics similarly defeated me.)

I've read that there is no variable for time in the equations used in quantum physics, no t, because (apparently) time doesn't play a role. That's why quantum effects that are visible at the macroscopic level - even something as simple as stuff that absorbs light to glow in the dark - are random processes time-wise.

Yet time t plays a crucial role at the macroscopic level, in classical, or "Newtonian", mechanics.

Not only that, time is malleable, in the sense that it is affected by velocity and acceleration (special relativity) and gravity (general relativity), effects that are not only measurable, but stuff we depend on every day (like GPS) have to make adjustments for it.

So suppose God has a dial that controls the scale of their point of view, all the way from the smallest sub-atomic scale we know of, the Planck length, to the largest cosmological scale we know of, the observable Universe. At some point as God turns this dial on their heavenly tele/micro/scope, zooming out, out, far out, time goes from not being a factor at all to being an intrinsic factor for whatever they’re looking at.

Does this transition happen all at once? Does it happen gradually - somehow - in some kind of jittery change? What the heck is going on in this transition? What other things similarly change at this transition point? Is this the point at which particle-wave duality breaks down? Where Schrödinger's Cat definitely becomes alive or dead? Where does gravity starts to matter?

Gravity? Yeah, gravity. Because we currently have no theory of quantum gravity. Yet it seems necessary that at the quantum level gravity ought to play a role in a wave/particle. If a particle is in a super-position of states, what does that say about the gravitational attraction associated with the mass of this particle? At what point on the dial does gravity make a difference? There's a Nobel prize for sure for the first person to make significant progress on this question.

This is the kind of thing I think about while eating breakfast.

Will Optical Atomic Clocks Be Too Good?

Read a terrific popsci article this morning in Physics Today on time keeping: "Time Too Good To Be True" [Daniel Kleppner, Physics Today, 59.3, 2006-03-01]. (Disclaimer: it's from 2006, so it's likely to be out of date.)

The gist of the article is that as we make more and more precise atomic clocks by using higher and higher frequency resonators (like transitioning from cesium atomic clocks that resonate in the microwave range to elements that resonate in the optical range), in some ways they become less and less useful. Eventually we will create (or perhaps y bnow have created) clocks whose frequencies are so high that they are effected by extremely small perturbations in gravity, like tidal effects from the Sun and the Moon. Or perhaps, I wonder, as clocks get more sensitive, even smaller gravitational effects, like a black hole and a neutron star colliding 900 million light years away (which has in fact been detected).

Even today, the cesium and rubidium atomic clocks in GPS satellites have to be adjusted for special (due to the centripetal acceleration of their orbits) and general (orbital altitudes over the center of mass of the Earth) relativistic effects, where, in round numbers, an error of one nanosecond throws the ranging measurement for a single satellite off by about a foot.


(This is an NTP server I built for my home network that incorporates a chip-scale cesium atomic clock disciplined to GPS; everyone needs a stratum-0 clock of their own. Also shown: my lab assistant.)

With far more accurate/precise atomic clocks, we won't be able to compare them. Note that relativistic effects aren't just jitter issues, they affect the fundamental nature of time itself, so it's not just a measurement or equipment issue.


(This is a photograph I took in 2018 of part of an experimental ytterbium lattice optical atomic clock at the NIST laboratories in Boulder Colorado.)

One of the problems with optical atomic clocks is that to compare two of them in two locations we have to account for differences in altitude as little as one centimeter; that's how precise these clocks are, and how sensitive they are to general relativistic effects. We simply don't have, and probably can't have, a way to measure altitudes from the center of mass of the Earth that accurately. One of the ways we measure the shape of the "geoid" of the Earth is to (you knew this was coming) compare synchronized/syntonized atomic clocks. So there's definitely a chicken and egg problem.