#i find it really hard to judge what the general level of science literacy (? is that a thing?) is

[serenpedac]

One of the things that has been on my mind as of late is The Three-Body Problem, both the recent Netflix series and Cixin Liu’s book.

This is not about some of the major things that people are probably discussing elsewhere, but just a few of my own thoughts on some details. I’m writing this down mainly for myself, but still wanted to share it somewhere, in case anyone is interested in my ramblings about astronomy and particle physics ^^

One of the things I love is the human-computer they make in the game. I'm not a computer scientist and can't comment on how realistic it is, but since computing is 1s and 0s, I can see the basics work. 

It also reminds me of an early simulation of cosmological structure formation in which they used people to act as particles. They were spread out and then given instructions about where to move, I assume based on which other person was closest, while also taking into account clusters of people would have a stronger effect than a single person. I tried to look up more details, but couldn't find anything, unfortunately, but it’s something that was briefly mentioned during a cosmology course.

The idea is similar to modern simulations, although it’s extremely simplified of course (see here for a beautiful example).

Another thing that stood out to me was the mention of Chien-Shiung Wu*. It’s a very brief mention and mainly in the context of being a woman in STEM, but I think she ties into the scientific side of the story as well.

[For this part, please bear with me and apologies if anything is not clear or incorrect. I’m not the best person to explain this as I really, really wanted to love (astro)particle physics, but that intention was rather one-sided. The few courses I took that dealt with it were a struggle.]

Early on in the story, the point is made that the results the scientists get from experiments are chaotic, they keep getting different results for their monitored particles despite having the same initial conditions. This means that “[...] the laws of physics are not invariant across time and space.”

This immediately reminded me of the breaking of symmetries in particle physics, because that also deals with particles behaving differently from what was expected according to the laws of nature known at the time. In particular the breaking of parity and time symmetry came to mind, as they are about place and time, respectively. And guess what? Wu discovered the breaking of so-called parity symmetry. Let me explain it a bit more ^^ 

Parity transformations are about flipping the sign of the coordinates (of, for example, the location of a particle). You can flip all three the coordinates (x,y,z) → (-x,-y,-z), but you can also just flip one. This ties into “mirroring”, for which you can imagine a mirror being placed on the y-axis, so that the particle’s x coordinate would be -x, as seen in the image below.

If parity symmetry holds for a particle interaction, that interaction would give the same result in a mirrored universe as it does in the “regular” universe.

Experiments showed that this symmetry held for the electromagnetic and the strong nuclear force, and it was expected to hold for all fundamental forces. Wu, however, found that this is not true for the electroweak force. She looked at radioactive decay for a form of cobalt and found that emitted electrons had a very specific preferred direction, which they wouldn't have had if parity symmetry would have held (I'm summarising and simplifying here).

Her result gave us a way of distinguishing left from right, scientifically, but also contradicted what was expected to be a general rule of physics: parity symmetry.

This had large implications for the world of particle physics and eventually led to the development of the Standard Model: a new theory that aims to describe the elementary particles and fundamental forces. (As happens so often with women who make significant contributions to science, her two male colleagues got a Nobel prize for this, while she was overlooked)

Obviously, these results are not the same as the circumstances in The Three-Body Problem—here, a new theory could explain the observed behaviour, whereas the story has unpredictable results—but both have particles that don’t follow the laws of physics that had been established before then.

So, my theory is that the mention of Wu is a nod to this breaking of a scientific paradigm. (I might be way overthinking this)

Finally, something that disappointed me was how in the chapter about the cosmic microwave background (CMB), there's this sentence "The universe itself was transparent; as long as you were sufficiently sharp-eyed, you could see as far as you liked." This is incorrect.

Right after the Big Bang, the universe consisted as a hot plasma, which was opaque. Photons were unable to get out, because the particle density was so high. They would basically be bouncing between particles all the time, never able to travel an extended distance. It is only as this plasma cools down and electrons combine with protons to form hydrogen that photons are able to escape, and these photons are what forms the CMB.

Because you look back in time as you look deeper into the universe, you would eventually encounter this "surface of last scattering", from which the CMB emerges. Beyond this point, you cannot see.

Normally, I wouldn't mind seeing the universe being called transparent for the sake of the storytelling, but to see this mistake in the same chapter that explains the CMB, when the two are tied together, irked me.

But overall, I am loving the book, although I haven't finished it yet (and there are 2 more). I prefer the way it sets up the story and how it feels more grounded than the series. Although I do like the characters from the series more than those in the book (Jin <3333 Auggie! Saul! Will!)

Kudos to anyone who has read all this!

*~*~*~*

Also, here’s a cool article that goes into finding solutions for the three-body problem. It’s by the one of the authors of a solution that is mentioned in the book.

*A confession: when reading her name, I would not have realised that Chien-Shiung Wu was the person behind the Wu experiment, but the translator’s note by Ken Liu mentioned that her work disproved the holding of parity symmetry.

All quotes are from this translation.