What exactly is "hot side aeration"?

The reason I ask is that I have read on the forum that you are not supposed to stir the wort vigorously while you are cooling the wort-------in my case in an ice bath. Yet, a few minutes later after transferring the cooled wort to the carboy, I am supposed to shake the carboy to provide oxygen for the yeast.

My understanding is, that there is a risk of oxidation (which is different than aeration) when the wort is hot. That being said, it’s widely considered to be a myth on a homebrew scale.

Bingo. It’s yet another one of those old rules of thumb that experience proves that you just don’t need to worry about at all because it doesn’t hurt a flea.

I use a wine degasser (mix/stir) to stir the wort as I’m cooling with my chiller. I don’t purposefully mix it hard, nor do I try to be overly gentle, but there is some splashing. This helps me cool my wort down in 10-15min tops. I have yet to have any issues with oxidation, hot side aeration, etc.

Some swear by it, I have never experienced it so don’t necessarily buy into it. I believer there must be some scientific sense behind it, but expect it’s one of those ‘not a concern on a home brew scale’ type things. But that’s just a guess.

A member of my brew club is a magician at making lagers. Either last year or the year before he won a Pilsner Urquell clone competition in NYC. Let’s just say, the guy really knows what he’s doing when it comes to lagers. His truly rival any I’ve ever had including commercial. He SWEARS by the theory of hot side aeration. We had a big discussion over stirring the mash at any point after initial mash in. Most agreed it’s not a problem, but he swore up and down to NOT do it.

Anyway, I do and don’t see a problem. This guy, who makes fantastic beer, doesn’t. So, you decide.