Some of the reactions here are a bit more negative than they need to be, given that you're fairly new to the site, so a bit more explanation is in order.
Tags are organizational concepts: they exist to classify and organize the questions that already exist on the site, and to make them easier to discover and link together. They are not magical beacons that will conjure up good questions on a given subject, regardless of whether said subject has been featured recently in Veritasium or not.
Tags are created as and when they are needed for the population of questions that already exists. As Jon Custer mentioned, there's some fifteen questions on aerogel on the site. This is not sufficient to call for the creation of a tag, I would say: it wouldn't do harm per se, but there's not really any great need for one at this stage. If you do think this is important enough (i.e. that there are enough questions, and that the subject is important enough to merit classification on its own), and you have 1000 rep, then you can create the tag yourself by taking a meaningful subject of the already-existing questions and adding the tag yourself.
(Generally speaking, the fact that the tag-creation privilege by regular users is available only at 1k+ rep is a strong nudge by SE that this is roughly the level of experience with the site and its workings that will give you a good grounding on whether the tag creation is appropriate or not.)
And just to emphasize: the lack of an aerogel tag does not mean that questions about aerogel are off-topic or that they are unwelcome here. So long as they fit the site, and there is at least one other tag on the site that describes them, then they're perfectly welcome. (If a question would be described by
aerogel but not by any other tags on the site, then it's a fair question as to whether it is actually on-topic.) So if people want to ask on-topic questions about aerogel, they already can.