"Same constraint likely applies - Bar?"

The only method the means for which are available here are door-based and require a patron to hold the door to whichever world you wish to visit.

"Are there records of other methods?"

Summoning is an example; there are others, none of which I expect to be learnable from books.

"Okay. Thanks."

I do apologize.

"We appreciate your help very much." 

"I'll take some books on summoning and on interdimensional travel in general," he says without looking up.

Bar coughs up three recommendations.

"Thank you," he says for his father, and hands him the books, and to Cam - "I want a list of priorities or something - there's multiverse stuff, there's recovering old lost magic in our world, if the notes aren't all magic themselves, there's figuring out if we have summoning and developing vaccinations to everything -"

"Vaccines are big but not even the only thing - flattening out the economy is big, electricity is big, global communication is big -"

"Flattening out the economy?"

"Making it easier to trade. Everything gets cheaper when that happens and stuff gets invented faster."

"Aaron's going to be all smug. I'm not sure it's worth waiting to repeal the Statute, actually - it'll be years -"

"It does seem like it'd be very annoying to work around in the meantime."

"The problem is that the Statute does a few good things I'd want to have other institutions in place to do, like 'not let people enslave Muggles' -"

"I believe in 1802 people are already enslaving Muggles, yes?"

"Muggles are enslaving Muggles and we are going to stop them. Wizards can much more conveniently enslave Muggles and are currently not doing that."

"I'm aware, but that's not what you actually said and if you're considering politicking among non-wizards you'll want to keep an eye on it. About how many wizards are there? How would one be caught if they decided to enslave some Muggles?"

"That's kind of the problem, Imperius isn't detectable. There're around two million wizards worldwide - we're about 1/500 -"

"...that's tiny, especially if you have any decent healing magic - are half your kids not wizards or did you just have a really early demographic transition or -?"

"Wizards' kids are almost always wizards, wizards do kind of get themselves killed a fair bit, average family size is in fact below two if that's what you mean -"

"That's what I mean. It takes birth control and a higher standard of living to get people to do that but I suppose magic gets you there sooner."

"We have birth control. I - don't actually know much about how convenient or scalable it is, or whether it's even safe for Muggles - Michael would -"

"There are very nearly perfect nonmagical options available, just not in 1802."