Weekly Head Voices #183: Wave functions wearing lycra.

This, the 183d edition of the Weekly Head Voices, looks back at the week from Monday November 4 to Sunday November 10, 2019.

In this post we have a BLoM, a story about the conflict between a man and a toy and finally some great quantum mechanics visualizations for your meat-based neural network.

On the way home from a compact but enjoyable Sunday party with built-in family gathering at Skilpadvlei near Stellenbosch.

BLoM (Bullet List of Miscellany).

  • Thanks to the gentle urging of my friend the Vogon Poet, I finally got around to fixing my custom Hugo shortcode for image inclusion so that it would use full path names. This will hopefully result in RSS feeds and the subscription email correctly displaying images.
  • I forgot to mention in the previous WHV that I wrote a post explaining how you can use Emacs and Orgmode to form and maintain good habits. This has really been working quite well for me.
  • It is hard to explain how happy I am that the comments on this blog are now also self-hosted using the open-source software isso. Of all of the advantages, I think I appreciate the lower barrier to entry the most. With full markdown support, you should be able to post whole blog posts down below in the comment section! (HINT HINT)

I should really look where I’m walking.

Picture this:

On Wednesday evening, as I was walking onto the carpet in our room, feet nicely marinated and super soft thanks to the shower I had just taken, senses and planning wetware focused on three different non-floor points in the room (I was carrying two items that needed to be deposited in two different locations, and I spotted genetic relation units on the bed), I managed to step right onto the single pink plastic toy my youngest GOU had left on the floor.

Naturally I did this with the softest part of my soft foot.

The plastic shattered, and somehow my reflexive foot action only served to result in a partial retract followed by an apparently inevitable rejoining of the vertical foot-toy-mashup, which on its part served to bring more bits of shattered plastic into membrane piercing force levels of contact with the soft underside of my foot.

Are you still picturing?

Relatively-speaking large floor, unoccupied with one small exception.

Single highly shatter-friendly toy, made of pink plastic.

Man manages to angle foot just so, applies copious force, and impales said foot on lone toy, not once, but multiple times.

Anyways people, measuring by the amount of blood and other KPIs, I can in all honesty say that this is somewhat worse than stepping on a lego.

Three days later, we extracted what was hopefully the last bit of plastic from the underside of my foot.

On the bright side, the tweezer from my Gerber every day carry (EDC) micro-tool has now shown itself excellent for the purpose of light home surgery.

Also on the bright side, this will hopefully serve as powerful reminder that I should really focus better on where I put my feet down at home, at least until the volume of toys starts to diminish in a few years time.

(On Sunday, I couldn’t not, so I did squeeze in a short and careful run. I was quite happy that everything did still seem to work, albeit with some extra feeling.)

Gravitational waves on the high seas of curved spacetime.

My favourite video showing the idea of how gravity warps (curves; bends) spacetime is the one below.

For those of you who prefer not viewing YouTube videos, let me do another “picture this”.


  • The gentleman explaining the idea has a sheet of lycra stretched taut over a circular frame. He makes a funny joke about it being an old swimming costume.
  • Placing heavy bearings on the sheet stretches the lycra down into a funnel-shape, as you would expect. (that reminds me of this tangential thing I wanted to tell you at some other point: it turns out your neural network had to learn explicitly that model of material stretching as you were growing up)
  • Throwing more bearings onto the lycra, one can see how the curved surface causes them to orbit around the larger bearings!

Well, isn’t that just a fabulous image to have in your mind’s eye right now?!

This is exactly how you can visualize the warping of the gravity field in which you and I and all of our friends and the Earth and all the planets and everything in the whole universe are snugly embedded!

This more than explains the old “action at a distance” mystery.

In other words, how is it possible that the Sun is able to exert a force on the planet-formerly-knows-as-Pluto?

Well, as you can visualize now, the Sun, being the baddest mofo in this valley, warps the gravitational field (enveloping us all) the most, and this is what keeps Pluto in orbit.

Anyways, as beautiful as this is, it is probably old news to many of you.

Let’s go on to my NEW story!

During a recent Lex Fridman podcast with the CalTech theoretical physicist Sean Carroll, Carroll non-chalantly mentioned that general relativity was simply the extension to the idea of warped spacetime of a change at one point of the gravitational field not being able to propagate faster than the speed of light to another point!


I had never thought of it this way before.

When an object accelerates, it emanates a gravitational wave which travels through the gravitational field at the speed of light. (Yes, these gravitational waves have been measured.)

Going back to our lycra visualization, it made intuitive sense to me that a change in the warping of the lycra, for example due to the heaviest bearing being moved by a giant hand, would have to travel at finite speed through the lycra material for the new warped configuration to have reached all of its corners!

At that point in the podcast, as if my brain was not reeling sufficiently from these brilliant new mental images of gravitational waves rippling through curved spacetime, just like the patterns formed by small rocks skipping over water, Carroll started explaining how we are all just quantum wave functions continuously getting entangled with each other the whole time.

I think I have just convinced myself what I will have to read right after I finish with Why we sleep