Astral Codex Ten

Robert Brown

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Robert Brown

Article

Robert Brown is a recurring person in the Astral Codex Ten archive, appearing 2 times across 2 issues between November 18, 2021 and October 20, 2022. The archive places it in contexts such as “Robert Brown published a paper basically saying”; “Robert Brown, who helped discover it”; “Brown noise was named after Robert Brown, who helped discover it”. It most often appears alongside 23andme, AB, Abraham Mendelssohn.

Metadata

  • Category: People
  • Mention count: 2
  • Issue count: 2
  • First seen: November 18, 2021
  • Last seen: October 20, 2022

Appears In

Source Context

Recovered passages from the original issue text. When the raw archive preserved outbound links inside the source passage, they are listed directly under the quote.

Highlights From The Comments On Great Families
November 18, 2021 · Original source
The trouble is that this isn't how science worked, back when it worked. One person would notice something funny--not necessarily a theoretical problem; often a pure disinterested observation of just the type Popper claims is impossible, such as when Robert Brown published a paper basically saying "Microscopic particles in my tea keep jostling around as if they were alive". Another person might propose a hypothesis, as when Einstein proposed that this Brownian motion resulted from the random movements of atoms. Then a third person might propose a test, and a fourth might conduct the proposed experiment and report the results. This entire process sometimes took a century or more.
Book Review: Rhythms Of The Brain
October 20, 2022 · Original source
Did you know: White noise was named because its wave spectrum resembles white light. Pink noise was named because its wave spectrum resembles pink light. Brown noise was named after Robert Brown, who helped discover it. This is one of my least favorite facts. Lots of scientists seem tempted to wax rhapsodic about the importance of pink noise; the exact reasons were one of the parts of the book I didn’t quite understand. For our purposes, it just matters that this is the overall wave spectrum of the brain. How is this spectrum formed? This was one of the questions the book didn’t resolve for me. Are there a few hundred neurons here oscillating at 1 hertz, a few thousand there oscillating at 1.1 hertz, and so on, until we have enumerated thousands of different neuronal populations with very slightly different rhythms, and when you add them together you get the nice smooth pink noise curve? And then after a second, they all spontaneously rearrange themselves and there are a different few thousand populations and rhythms, still on the aggregate summing to pink noise? Sometimes it seems like the book is pointing to a model like this. Other times it seems like there are approximately five different rhythms in the brain, each with a name like “hippocampal theta” or “visual alpha”, and each usually involving a whole brain macroregion (eg the visual cortex). I still haven’t figured out how to reconcile these two perspectives - maybe the major rhythms are broad categories, and there are lots of subrhythms within them? In any case, these 1/n rhythms form the “background noise” of the brain. They exist at all times, whether you’re thinking hard, or in a sensory deprivation tank, or asleep (although each of those states will change which rhythm predominates). When neuroscientists want to study how the brain reacts to something, they usually measure the brain, do the thing, and subtract the pink noise spectrum from the result - again, on the grounds that it’s “background noise” which is disguising the effect of whatever their interesting intervention was. Buzsaki questions this practice and presents evidence that the state of the “background noise” matters a lot - this is the “randomness” that explains why the same person will respond to the same intervention different ways at different times. For example, he presents evidence showing that if you give someone a near-threshold stimulus (for example, a flashing light just barely bright enough that someone can detect it 50% of the time), then whether they detect it or not will depend on whether it occurs at the peak or the trough of the brain waves in the relevant area. Are Brain Waves Useful? Brain waves are kind of unavoidable. Rhythms presents a thought experiment about trying to design a brain that doesn’t fall into any natural oscillatory patterns. It’s pretty hard! Even if brain waves were useless, we would probably have them just because they’re too much trouble to avoid. Still, evolution tends to make virtues out of necessity, and Buzsaki thinks brain waves matter a lot. Again without claiming to have fully understood this, here are four things that brain waves might do: Brain waves provide “synchrony”, allowing a smallest granular unit of time and essentially converting life into a turn-based game. Suppose that a snake bites your foot. You see the snake with your eyes, and also get a pain signal from your foot. The pain signal has to travel a long way, nerves have conduction delays, and so it reaches your brain well after the visual signal. But your brain needs to be able to combine the visual and pain signals into a single story (snake bit my foot). Brain waves separate experience into short granular “turns” so that the brain can attribute both stimuli to the same “turn” and connect them. It’s also possible I’m totally misunderstanding this part, sorry.