Physics, Math, and Life

In graduate school, you are training to become an independent researcher, that's basically the whole idea. The common ideal archetype is the "multiple first-author papers grad student who never needs help nor asks questions". And while being able to lead a project to the natural conclusion of a paper is an integral skill, it's rarely done alone or entirely independently. In truth, research is typically very collaborative and it's rare to work alone.

My more recent interpretation of becoming an "independent researcher" is more about learning how to be responsible for your own work. This means taking the initiative to see it complete and correct. This can look like asking for advice from other experts, teaching collaborators so they can get up to speed, or double checking that your work is consistent with other literature/logic.

[Many college students experience introductory physics as psychologically threatening.]

I was reading one story where the apocalypse was impossibly-rising oceans. Like, water is appearing from *waves hand* the Earth's crust or something, and literally all dry surface land on Earth is going to become underwater in X years. Part of the story was about a giant research project to invent FTL to send a few hundred humans to a nearby star which might have a habitable planet. You know what they were hoping to find? A planet with liquid water. Their plan was to descend from their starship and restart civilization using just the tools they brought with them, on a world with no life and no breathable air and the wrong gravity and the wrong temperate and the wrong sunlight and the wrong day-night cycle, just because it had liquid water. You know where else has liquid water? The flooded Earth you just abandoned. Instead of researching starship technology, you could have spent that time loading up all the same civilization-restarter tools into boats.

She got the idea for the study while walking with her advisor at Stanford to discuss her thesis topic, and the paper she eventually published in the Journal of Experimental Psychology in 2014 is sharp enough that it should have ended the seated meeting on the day it came out.

She ran 4 experiments on 176 people. Same person tested twice. Once sitting, once walking. The creativity tasks were the standard ones psychologists have used for decades to measure how good a brain is at generating novel useful ideas.

81% of participants in the first experiment produced more creative ideas while walking than while sitting. In the second experiment, 88%. In the third, 100%. Every single person walked into a more creative version of themselves. On average, people generated 60% more novel useful ideas the moment their legs started moving.

The skeptical question is the obvious one. Maybe it was the fresh air. Maybe it was the scenery passing by. Maybe it was the change of environment doing the work, not the walking itself.

Oppezzo killed every one of those explanations with one experimental decision. She put people on a treadmill facing a blank wall. No scenery. No fresh air. No environmental change. Just legs moving in place while staring at white drywall. The 60% boost held.

Then she ran the experiment that closed the case completely. She took participants outside in two conditions. Half of them walked through a Stanford courtyard. The other half were pushed through the exact same courtyard in a wheelchair. Same outdoor stimulation. Same scenery passing at the same speed. The only difference was whether the legs were moving.

The walkers produced dramatically more novel high-quality ideas than the wheelchair group. The outdoors did almost nothing on its own. The walking did everything.

She also tested the opposite kind of thinking. Convergent thinking. The kind where there is one right answer and you have to narrow down to it. Word puzzles where 3 words share a hidden fourth word that connects them. The seated participants did slightly better on these. Walkers got slightly worse.

Walking is not a general intelligence enhancer. It does one specific thing. It opens up the divergent search inside your brain. The part that generates options. The part that produces unexpected connections. The part that takes a problem and finds five ways into it instead of one.

When you need to converge on the single right answer, sit down. When you need to find the answer in the first place, get up.

The mechanism is now well understood. Walking selectively activates what neuroscientists call the default mode network, the system inside your brain that runs when you are not consciously focused on anything. The DMN is where mind-wandering happens. Where memories cross-reference each other. Where ideas that have been sitting in separate folders inside your head finally bump into each other.

When you sit at a desk and force yourself to concentrate, you suppress the DMN. When you walk at a natural pace, the executive part of your brain gets just busy enough handling the walking that the DMN comes online and starts doing the work that focus was blocking.

The most useful finding in the entire paper is the one almost nobody quotes. The boost did not turn off the moment people stopped walking. Participants who walked first and then sat back down stayed elevated. Their next round of seated creativity work was still significantly better than people who had been sitting the whole time. The rest lingered for at least several minutes after the legs stopped moving.

You do not need to do creative work while walking. You need to walk before the creative work. The brain holds the state.

1. make a syllabus for yourself - books, media, places, recipes

2. complete 40% of it

fusion happens when atoms hit each other really hard, but they dont usually want to hit each other. they need to be forced into it. you can do this by getting them really hot, which makes the atoms move faster, which much like cars doing 90mph in a 65 zone increases the chance of collision

really hot atoms in a really hot gas become what's called a plasma, where all their electrons fall off so the leftover positive nuclei are floating around with negative electrons

therefore, fusion research consists of trying to get plasma hot enough to fuse.

two problems

it has to be really really really hot to fuse

really really really hot plasma is bad for nuclear reactors, humans, and everything that isnt the sun

solutions arise

plasma is electrically charged, so we can control it with magnets. magnetism and electricity happen at right angles to each other, like if an electron is moving vertically a magnet can pull it horizontally, and vice versa

if we get the plasma to whirl around in a circle, we can hold that moving plasma flow in place with magnets

behold! the tokamak

it would be nice if it worked out that neatly, but plasma is really messy and ends up drifting all over that place. it turns out that doing the spiraling helical thing in the diagram is the best way to contain it, but it's not 100%

and even trying to confine it like that needs a huge amount of energy to get a huge amount of electricity flowing through the plasma to get it magnetically active enough for the magnets to hold it in

when people speak of "nuclear fusion in ten years!" they mean that we will achieve "breakeven", when the amount of energy used to just run the thing is "worth it" because we get more energy out

but plasma remains messy, and every time it messes up it costs energy and damages the reactor. an early tokamak had a hole melted in it by what we later understood to be very similar to a literal lightning bolt

the tokamak is a somewhat brute-force approach. what if there was a more elegant method

though we don't yet understand all the messes of plasmadynamics, we understand many of the biggest ones, so we can come up with ways to cancel them out.

one of the easiest ways is rotation: if the plasma drifts left, let it get halfway and then flip it upside down so it drifts back right. or constantly keep rotating it. you can see the same idea on the helical magnetic field in the tokamak diagram from before

so in a stellarator, we've switched our focus: instead of relying on flowing plasma current to respond to the magnets holding it in place, we've reshaped the magnets to catch plasma drifting outwards and redirect it back inwards.

pros: no messy, power-hungry plasma current to force. a stellarator can operate in "steady-state": instead of constantly touching it up like pottery on the wheel, it just goes until you turn it off (or it runs out of fuel or explodes of whatever). since we're already fucking with the magnet shapes, we can also put in extra little twists to trap plasma messes, smooth out the more obvious tangles, etc.

cons: all that magnet fuckery is complicated. it's harder to calculate and design, harder to physically build, and harder to maintain. depending on the design you can make it so the magnets are movable, so for a research stellarator you can try new magnet designs a little easier, for example, but that movable magnet will never be as good as a properly fixed magnet. also the magnets have to be quite close together so there's not really space to build, like, a door into the interior for maintenance or access

and the real con: tokamaks are better. they quickly got much closer to breakeven as we just continued to refine our plasmadynamics alongside brute-forcing the plasma current

BUT

stellarators are getting better

i almost wrote that theyre getting beautiful. they are. just look at her