There's this very beautiful software called MMANA-GAL, that lets you model radiation patterns of antennas.

By beautiful, I very much mean that it's beautiful below the surface. Visually it looks awful, and it's not very easy to use. But it's very very good.

I've been using it to try to design a highly-directional foldable Yagi-Uda antenna, for use with a handheld #hamradio. If I can get the impedance right, MMANA-GAL says it could have around 13.3dBi of gain, which is to say that signals in the "best" direction are about 20x stronger than if you instead used a hypothetical perfectly spherical antenna.

And the design is basically made of 10 wires, sewn into a 1m square piece of fabric. I'm pretty excited about this, because if it works it should be really easy to carry around in a backpack (~as unwieldy as a t-shirt), and it will mean that you should be able to use a teeny 5W radio to communicate over really long distances (as long as you know which direction you want to talk). I've seen someone make something like this that let him use such a radio to communicate nearly 100mi! Normally these radios can communicate at most 10mi.

There is an important and intuitively obvious sense in which humanity is collectively much more powerful than any other group of animals. This sense is surprisingly difficult to make explicit.

Certainly there are some species of animal, like chickens, whose entire existence is dictated almost entirely by human whims. But are humans more powerful than rats?

Humans would like it if there were fewer rats in our cities. And we have even eliminated rats from some places: The Canadian province of Alberta has a 70-year rat control program that has been wildly successful. It is believed that there are no breeding populations of rats anywhere in the entire province. More than half a million square kilometers, rat-free.

Even so: large as it is, Alberta represents less than half a percent of the landmass of Earth. Why haven’t humans eliminated rats from other inhabited regions, assuming we’d like to?

The answer is, basically, that even though we have god-like power from the perspective of rats, our resources are limited, and we address problems based on their urgency and cost.

I don’t think many reasonable people would claim that the apex animals on our planet are rodents (in fact this is a humorous worldbuilding element in The Hitchhiker’s Guide to the Galaxy). If humanity collectively decides it wants to demolish a building, drop a nuclear weapon, or test a new drug, the rats, whose lives will be created, destroyed, uplifted, or immiserated, aren’t consulted or even much considered.

And as we go about changing the world to suit our preferences, the rats will remain unconsulted. It seems clear to me that rats will only get what they want when what they want happens to be nearly-costless to humans.

From Andres Gomez Emilsson on Facebook:

A friend of mine (Taru the Qualiaphile from Finland) made this tool to train your ability to identify and name wallpaper symmetry groups.

For example, the one I posted here is X which means that it's a symmetry group that has one "reflection" () element and one "glide element" (X). The reflection is the normal mirroring we all know and love. "Glide" mean "translation and reflection". This picture has both of those elements, and nothing else, so it is called *X. There are 17 symmetries like this (their names also pictured here).

This is a very useful skill to have to be able to report your visit to spiritual places and beautiful architecture such as temples and churches (which are full of wallpaper symmetries) as well as being able to describe the phenomenology of exotic states of consciousness. With this website you can train yourself to notice and name them quickly, and thus gain this precious skill!

Of course interacting with this tool will ultimately change how you see the world - your visual system can get better at quickly rendering scenes when there are vague hints of symmetries because it can then find the wallpaper symmetry group that best approximates it.

Play with it for 15 minutes and a "Tetris Effect" begins to happen. You might have unusually symmetrical dreams that night 🙂

taru-u.github.io/apps/symmetry…