January 30, 2016 at 02:34AM

Today I Learned: 1) Don't empty bottles of LB-agar into a sink. You'll end up with lots of annoying chunks that are hard to clean up. Just dump it out in the trash can to begin with. It'll smell really funky, but it's not actually that messy and it ought to be totally sterile. 2) The Plank length is the fundamental unit of length in nature, and is thought to be effectively the smallest size a thing can be. ...or that's what I thought. Apparently that's a common misconception. Today I learned that there is no such thing, and it makes no real sense to talk about a "smallest size of thing" (the reason is relativity -- if you made something of the "smallest possible size", there would always be a reference frame you could come up with where that thing was smaller due to length contraction). The Plank length IS a thing, just not THAT thing. It's roughly the distance at which you have to stop ignoring quantum gravity, which is a concept I don't really understand. According to Wikipedia, which I may or may not trust on this matter, it's also roughly the smallest *measurable* distance. That's not an experimental limitation -- it's just that below that scale, traditional notions of distance aren't very useful because stuff is smeared out too much. Also according to Wiki (and I trust this fact more), a 0.1 millimeter dot (about the smallest speck you can see) is as much bigger than the Plank length as the universe is bigger than a 0.1 millimeter dot. That's a really small unit of measurement! The other cool thing about the Plank length is that it's defined entirely in terms of fundamental physical constants, so it doesn't depend on your choice of units (just your choice of universe). 3) 2 AA batteries (3 volts) is sufficient to split water with a graphite cathode and a graphite electrode. 1 AA battery (1.5 volts) is not. Slightly relatedly, volt meters apparently tend to use a special 12-volt battery that looks like a AA battery squashed down to the length of a AAA battery.