I remember, in my university days, having a serious argument with a lecturer over the nature of life. He stated that life existed only on the boundary of types of material, e.g. solid and gas for us. He stated that it could not exist elsewhere. I challenged him, and his basic putdown was because we hadn’t found it, it didn’t exist. Fucking idiot, but he carried the class with him. Well, it turns out I was right. Not only can life exist within one kind of material, it looks like there’s rather a lot down there: Microbial life in deep granitic rock (Science Direct)
Another lecturer in another course assured me that faster than light was impossible, and the idiot came up with the same stupid argument: because we don’t know how to do it, it can’t be done (my argument had been that because we didn’t know how to do it doesn’t mean it can’t be done). Again, it’s nice to discover he was wrong. Admittedly, the science of the Alcubierre drive is deep speculation, but the very fact this deep speculation exists shows that serious scientists don’t believe it’s impossible.
It’s satisfactory finding that someone you think is wrong is wrong, but it’d be a little nicer if it had been provable at the time! Ah well.