Tag Archives: logic


Organic computing, anyone? Ars Technica reports on a paper published in Nature, wherein the authors describe the creation of bacterial colonies that can act as logic gates:

The key to the new work is stretches of DNA that act as logical OR and NOR functions. Both of them rely on small stretches of DNA called promoters that control the activity of nearby genes. In this case, the authors used promoters that activate nearby genes in response to simple chemicals (arabinose and tetracycline for these two promoters). By putting both promoters next to a reporter gene, the system acted as an OR gate: when either of the chemicals was present, the reporter was on.


the authors set up small clusters of bacterial colonies (small lumps of genetically identical cells). Each colony had a single logic gate (the authors used NOR, OR, and NOT gates). Depending on the arrangement of the colonies, each one could signal to only one or two neighbors, and each could only take input from one or two. The authors demonstrated a functional XOR gate built from four colonies, showing that all logical functions can be built from similar combinations.

The nice thing about using populations of cells is that this averages out some of the chaotic behavior typical of systems based on single cells. At a minimum, the systems they tested showed a five-fold difference between their on and off states. The downside is that, relative to a single cell, these systems are huge. The authors suggest that it might be possible to adapt their system to single cells, but it’s not clear that the same sort of performance could be maintained.

Boole meets biology. Maybe one day we’ll grow computers instead of building them from silicon slices…

Fractal levels of simulated reality, forsooth!

I’m sure I ran a story similar to this a while back, but I’m damned if I can find it in the Futurismic archives, so I’m gonna mention it anyway: it’s the one about the folk building logic-based processors within the virtual spaces of computer games, the latest example being the insanely popular (and rather lucrative) Minecraft. Find blocks of material with the right in-game properties, chain ’em together, and hey presto, you’ve got a simulated arithmetic processor made of non-existent lumps of an entirely fictional substance. Whole lotta meta, right there.

I think the reason I love these stories is because of the extrapolatory end-point: the implication is that given simulated spaces of sufficient size and complexity (and sufficient player-hours, or clever macros to obviate the need for such), one could build a computing device within that simulation which was itself capable of running a simulation within which another computing device could be simulated. Sort of like Nick Bostrom rewriting Lavie Tidhar’s “In Pacmandu”… it’s simulated turtles all the way down! Now, where’s the door back to my origin reality, please?

UFO sightings coincide with UFO movies

flying saucersVia Futurismic‘s long-term good buddy Mac Tonnies come the results of an analysis of the UK MoD’s “x-files” documents, recently released to public scrutiny; apparently UFO sightings were more common around the times at which popular films or television shows featuring alien races or spacecraft were screened. [image by eek the cat]

The obvious conclusion here is “well, skiffy movies cause alien sightings; case closed”. But as Mac points out, that’s not logically sound:

There’s doubtlessly a correlation between science fiction and UFO reports. But while pop culture’s influence on potential UFO observers is a fascinating subject with important sociological ramifications, to flaunt Clarke’s findings as a refutation of the phenomenon in general is to willfully ignore the evidence in its entirety.

UFO researchers aren’t interested in “noise” cases — the inevitable false alarms that plague efforts to study the phenomenon (whatever its origin). Indeed, scientists who have addressed the UFO problem have always been painfully aware of the disproportionately high volume of false returns.

Now, you may more skeptical than Mac regarding the causes of UFO sightings, but his point still stands – divorce the logic from the specific subject matter, and the same applies to any sort of genuine scientific enquiry. I’m pretty sure this is what they call confirmation bias at work, and it makes me wonder how often it affects us…

… although it obviously happens often enough for it to be politically useful. 😉

ZOMFG kkkonspiracy!!1

Wired has a run-down of the ten most popular conspiracy theories, which will either raise a wry chuckle out of you or fire you up into a paranoid rant-fest, depending on your personal belief systems.

I’m kind of fascinated by conspiracy theories, and when I was younger used to subscribe to quite a few (mostly the UFO-related ones, I’m ashamed to admit – a classic case of wishful thinking). Curiously, the book that completely cured the problem for me was Robert Anton Wilson and Robert Shea’s conspiracy classic, The Illuminatus! Trilogy.

It’s apparently the innate pattern-recognition functions of the human mind that create conspiracy theories wherever we find a vacuum of fact surrounded by unexplained events … how long do we have to wait until Occam’s Razor becomes hardwired, I wonder?

[tags]conspiracy, theories, psychology, philosophy, logic[/tags]