Hey everyone, I just thought I would post this here today since this blog post is becoming way more extensive than I originally thought. I just finished up writing the introduction, which is basically about the philosophical core of the many-body problem in condensed matter physics. I figured that it would be best to get all the philosophy out of the way first, since doing science without philosophy is just looking at numbers.
I'd really appreciate some feedback, since this is setting the tone for a lot of the piece I have so far. (I actually haven't outlined it yet, I wanted to freeball this intro.) Please let me know if there's anything you didn't get, or anything that you think needs work.
I've written a fair amount of this within the past hour, and I'm sleepy, so that may have impacted the quality quite a bit.
Everything you've ever held is buzzing—electrons, atoms, and photons are all
moving about, interacting with each other, and holding together any object
or being you've ever smelled, heard, felt, seen, or tasted. People have always
wanted to understand what they interact with, and there's a great tendency
towards what philosophers call reductionism, where scientists ask what
something is made of, what the things that create that thing are made of, so on
and so forth ad nauseum until eventually people arrive at the thing, the
most fundamental object in the universe. You can see this sort of reductionism
everywhere in physics if you know where to look—it's particularly present in
the kinds of physics you see on TV, namely high energy physics (string theory
in particular).
Reductionism has been successful to a point. We would never know about the
atom's structure if people never asked what the atom was made out of—people
would keep assuming it's an unbreakable sphere, or worse, like Ernst Mach,
nonexistent. However, we can never know how something behaves simply by knowing
what it's made of. I can look at a sandwich with condiments, vegetables, and
meat, and say "ah-ha, I know exactly how this will taste because I know what
all of its ingredients taste like!" Sure, you can know how ingredients taste,
but do you know how they'll work together? Do you know how, say, juices from
a bit of chicken will interact with some tomatoes until you take a bite? Of
course not. Even if you know about how a sandwich tastes, that's till not
giving you all the necessary information about that sandwich.1
Everything is more than what composes it.2 Take for example a living
organism, which is, technically speaking, just a bunch of cells—what makes
life possible, more than the existence of cells, are those cells interacting
with each other, and all the little chemicals inside those cells interacting
with each other. Life didn't simply start because one day a chemical decided to
do a bit—life is an emergent process, started from billions of years' worth
of chance, physics, and chemistry.
Much in that same way, it's impossible know how a material behaves simply by
knowing what it's made of. If I scream "molybdenum disulfide" are any of you
really going to know its optical or electrical properties? I'd certainly hope
not. (If you can do that, what the hell are you doing reading this?)
In order to understand anything other than the bare minimum about a material,
we need to understand how its atoms and electrons interact, how photons
interact with that material, and more—there's a lot of stuff to take
into account. If you want to learn everything there is to know about a
material, you could, hypothetically, write down a long Hamiltonian—a statement
of a system's kinetic and potential energy—and solve tons of equations
for a bunch of particles at the same time, be my guest—though be warned that
no one has done that in the past 100 years. If you want to do calculations for
a realistic system, you need to calculate the properties of at least 1023 atoms all interacting with each other.
So, there's much ado about nothing. We can't realistically know the properties
of a full system of interacting particles, but we need to know how they all
interact in order to understand the system! What are we gonna do? There's got to be a secret solution around here.
Simple, siis—work smarter, not harder. We must accept two things: first, as
lousy physicists, we must accept that what we're attempting to do is hard;
second, as discussed with sandwiches earlier, more is different.
-
Given my piece about Tears of the Kingdom, I think that food metaphors
are becoming a mainstay on here. -
I'm not just saying that to end up on someone's 2014–2019 Instagram
post.