Content note: profanity, physics
This is my second attempt to gesture flailingly at an epiphany I had a little while ago. It won’t be the last, I think.
The following conversation is inspired by a true story. Since that doesn’t actually mean anything, it’s probably best to assume it’s all fiction. Any resemblance to real persons has been exaggerated and distorted for comedic effect and bent to my own rhetorical purposes. All errors, inaccuracies, and failed attempts at humor are mine alone.
“You can’t turn shit back into a banana,” says my best friend, Mark Twain.
“Sure you can,” I say. “Just plant a banana tree.”
My other best friend–let’s call her “Tran Mawik”–jumps in.
“Sure, but then the tree needs air and water and shit, too. I mean, other shit.”
“Yeah,” says Mark. “It’s not a closed system. If you can just pump in negentropy from somewhere else, that doesn’t count. Total entropy still goes up.”
(We’re discussing the second law of thermodynamics.)
“So put the banana tree in a terrarium. Totally closed off, self-sustaining.”
“No,” says Tran, “it’s not closed off. Terrariums are made of glass. What goes through glass, dipshit?”
“Oh, yeah,” I say. “It needs sunlight. Duh.”
“Right,” says Mark. “If it really were totally closed off–no light or heat or anything getting in–it would only last until, y’know, everything had been turned into shit.”
“Microbe shit,” I say.
Tran nods.
“Still,” I continue, “it doesn’t seem like the best metaphor. Since it’s not literally true unless you add in the very conditions you’re trying to metaphor…ize.”
“Metastaphize,” suggests Tran.
“Metastaphose,” I correct.
“Metaphallate,” muses Mark.
Tran and I nod sagely.
“Maybe it’s more like…getting brownie batter out of a bowl?” I venture. “Like, it’s really easy to put all the ingredients in and mix them together and so on, but when you try to get the batter back out again you’re either left with some wasted batter still sticking to the bowl, or you have to work really hard to scrape it all out.”
“Yeah. Yeah!” says Tran. (We’re all taking physics classes, but she’s the only one actually majoring in it.) Mark considers.
“And even then,” I say, gathering steam, “you’re never gonna get it all out. The only way to get the bowl totally clean again is to wash it, which creates waste. The batter that you mix with soap and water and flush down the drain is never gonna be brownies. Or shit.”
“But you could get all the batter out, in theory“, says Tran. “It’s not physically impossible.”
“YEAH!” Mark explodes. “Yeah, motherfucker, but to actually do that would take a shit–ton of work. Scraping wouldn’t be enough, you’d need…I dunno…solvents? Edible solvents?”
“Special equipment?” says Tran.
“BATTER EXTRACTION FACILITIES,” Mark says with a manic grin.
“I mean,” I say, “if all else fails you just wave your hand and say ‘nanotechnology’ and you can turn energy into any kind of work. But I think it’s safe to assume ‘scrape the batter out with nanobots’ takes more energy than ‘dump the batter in with gravity,’ right? So it’s still a good fit, I think.”
“No, asshole, it’s a better fit!” Tran says, stabbing her finger at me in a way that would feel threatening if she didn’t do it at least three times a day. “The second law is probabilistic. It’s not physically impossible to violate it, it’s just…impossible to violate it on purpose.“
“Yes, exactly!” says Mark. “And the chances of it happening by accident are, like, infinitesimal. You’d have about the same chance of–oh, I dunno–the batter spontaneously pouring itself out of the bowl.” He pauses for effect.
“Isn’t that–” I say.
“THAT’S EXACTLY WHAT IT IS,” he enthuses, bouncing up and down in his chair. “THAT’S EXACTLY WHAT IT WOULD BE. All of the molecules in the batter just coincidentally having exactly the right configuration that the momentum they already have just…” he makes a motion with his hand like a leaping dolphin.
“Wait,” I say, “I thought the second law of thermodynamics was, y’know, a law. You’re telling me it can be violated?”
“No, NO, asshole!” Tran says, at the same time Mark starts “Yeah, but–“
The two exchange a look.
“The conditions have to be just right,” says Mark. “The circumstances are so special they basically never happen. So it is a law.”
“Motherfucker, no,” says Tran fondly. “Laws are laws, not suggestions; they don’t have exceptions.”
“I’m confused again,” I say. “Didn’t you just say it can be violated, just not on purpose?”
Tran gives me the withering glare she reserves for those occasions when I’ve just convinced her she’s wrong about something.
“YES,” she says, leaning forward so her black hair hangs over her face and makes her look like an older version of the little girl from The Ring. “YES I DID SAY THAT. AND IT WAS FUCKIN’ WRONG.”
“Okay,” I say, “so…?”
“Alright, look,” Tran says, combing back her hair with her fingers, “you can turn shit back into a banana. The second law doesn’t prohibit that. All it says is that it will take at least as much work to get your banana back as it took to make the shit. The part of the law that can sort-of-not-really be violated is the probabilistic part that says it will pretty much always take more work.”
“Ah,” I say. “So, you can get a free lunch sometimes, but you can never get paid to eat it?”
Mark starts laughing the way he only does when I’ve said something exceptionally harebrained, so I know the joke landed.
Tran is still focused on getting her point across.
“Ehh…kind of?” She sighs in frustration. “It’s not really about…paying for things. It’s more about not being able to undo things. Like, you can turn shit back into a banana, but not the same banana. Up to the limits of physics, you can do anything you want with the future, but you can’t recreate the past.“
“So…the second law prohibits time travel,” I say.
“Yes, actually!” says Mark, jumping back in. “Time travel isn’t technically impossible, all the laws of physics are CPT-symmetric–“
(I don’t know what that means, but Mark’s got too much momentum now for me to stop him and ask.)
“–so on the level of individual particles there’s nothing ruling out traveling to the past, but getting all the particles, everywhere back the same way they were can only happen by a coincidence so unlikely it might as well be impossible.”
“Yeah,” says Tran, “or you can put small pieces of the system back almost exactly the way they were, but only by messing up other pieces even more.”
“Okay…” I say. “So, you can turn shit back into a banana, but only by scraping batter out of a bowl somewhere else?”
“Exactly!” shouts Mark, throwing his hands in the air.
Tran nods in approval, probably only mostly tongue-in-cheek.
I turn to the paper in front of me. Typed at the top is our assignment: In your own words, explain the second law of thermodynamics. I start writing.
The second law of thermodynamics states that you can only turn shit back into a banana by turning something else into an equal or greater amount of shit, and the more closely you want the new banana to resemble the original, the more additional shit is required.
I turn the paper around so my friends can read it.
“Perfect,” they say in unison.
In Search of Secrets 