"I leave the diplomacy to the supreme elect; Codwin's got a good head on his shoulders, and I'm busy enough with running the university. Scrolls I can do, though you'll want to be careful with gate summoning; a scroll isn't strong enough to control anything more powerful than a Planetar safely, and you'll still need to negotiate payment separately for whatever you summon. I strongly advise anyone who isn't an experienced binder to stick to willing summons."

"That's good advice and I intend to follow it. I expect there are very few circumstances where compelled assistance is better than willing help." Also she's not particularly planning to use Gate for summoning any time soon, but she's trying to get in the habit of not telling everyone everything about her plans.

Gate scrolls for summoning are pretty expensive, what with having to use up the incredibly valuable incense and offerings during the scribing process, but discern location is significantly more reasonably priced and neither is outside of what she can afford.

Excellent.

"What is the function of the incense and so forth? Does it compensate the target plane for their intervention budget somehow?"

“No, it’s a requirement to let it target by creature instead of by location. Responding to a summons by gate is cheaper than manifesting directly, but if what you’re calling them to do isn’t something they really want to do anyway they’ll usually want compensation to make up for it.”

"Is it possible to make a cheaper version that targets a location, or does it only stabilise the one way?" It's a question that might have practical applications, but she wants to know even if she doesn't decide to explain her plans for the scroll.

"Significantly so. That one doesn't take any materials besides what you need to stabilize the spell scaffold in the scroll, but even if you have the incenses available you can't then use it to call an outsider; it's just usually worse than just plane shifting unless you can't get a tuning fork."

It's going to be obvious what she's using it for when she uses it anyway, since she'll be doing it in front of hundreds of people. "I'd actually prefer to purchase one of that type, if you have one available. I'm intending to use it to get around the limitation on number of targets for a Plane Shift."

"I don't have one prepared without, but they only take a day or two to make. How many do you think you need?"

"Just one for now."

"Then I'll get it to you by tomorrow afternoon."

They get all the way through the delivery logistics before Brenda nerd-snipes herself with a question about how gravity works in demiplanes. Surely there isn't a sufficient amount of mass hanging around for ballast?

This one is a little bubble off the ethereal plane, so it borrows the local gravity, but if you cast the 8th circle version of the spell you can change that with experimentation and a bit of tricky spellcraft. She'd normally be willing to demonstrate, but in addition to it taking two eighth circle slots to do and undo it the spell takes four hours to cast. 

Totally reasonable not to demonstrate that. Brenda hasn't learned anything with a casting time anywhere near that long, yet; is it as much mental activity as casting a short spell for the whole time or are there long periods of just waiting and watching while things proceed basically deterministically? Do wizards know about gravity being a result of space being curved? Is that even true around here?

It's a fairly intense kind of focus required - create demiplane isn't nearly as bad as what it takes to do a hallow, but it still requires a lot of attention. If you get too jostled or distracted or otherwise interrupted while casting it, the spell fails and unravels from the scaffold, but the more experience you have with casting and the more talented you are the easier it is to not screw up - concentrating on harder spells is harder, but usually by less than casters get more skilled before they can cast them. If she had a silent rod for it or was using a telepathic bond, she could carry on a conversation while casting it, but you'd probably be able to tell you didn't have her full attention and she certainly couldn't cast another spell while doing it.

"Hmm, what would it even mean for space curving to cause gravity - no, that makes sense, actually, the same way a straight line on a sphere curves. I wouldn't expect that to be be the cause, it doesn't match my intuitions from reverse gravity, but it's possible the spell is just misnamed, and uses... telekinesis, maybe, there are some similar components in the structure, though then you'd expect heavier objects to fall upwards more slowly..."

It's quite possible that gravity works differently around here than where she first learned about it! She'd need to remember and rederive a bunch of math in order to even know exactly what experiments to do. Well, in principle she could check whether light has a speed and how fast it is and whether Greater Teleport is faster, that would be suggestive. What does her experience with Reverse Gravity suggest?

(Ironically, this conversation is itself causing time dilation. Friendship!)

Reverse gravity is a seventh circle transmutation spell - one of her favorites, in fact, since it completely ignores spell resistance and most defensive abilities other than flight.You create a number of ten foot cubes of space in which things fall upwards at the same rate they would otherwise fall downwards, which if you do it indoors leaves them falling into the ceiling and outdoors just being stuck midair. Her intuition is that if it worked on bending space there would be different behavior at the edges, but instead of you make it to the top you shoot outside the zone a little, fall back down into it, and then spend a bit oscillating until about half your mass is on each side. It also doesn't do anything to obscure or lens vision.

Wow, yeah, with the kind of gravity she's familiar with she'd expect weirder behaviour at the edges. At least for a strong enough gravity field. She wonders what would happen if you cast it on a heavier or lighter planet, or in outer space--if you go to outer space you're in free fall, right?

"It's less powerful on the moon, but I've never checked on the other planets; by the time I could get to them, I was pretty much retired from adventuring. As for space... well, there's still gravity in freefall, so I expect it would work about like normal if you were close enough to the planet, but anyone who's not in orbit has some way of getting around that it wouldn't block, and if you were in an orbit you'd leave the spell behind pretty quickly."

"It's really cool that you've been to the moon! I wasn't even thinking about using it on someone, just about whether the spell would do anything noticeable if you were far from everything and not in orbit."

"I expect it would work at least a little, as long as you were near enough to the sun, but if you went out far enough past the stranger... hmm. I expect you could notice it if you were careful in measurements, but not otherwise."

"That sounds right, but what's 'the stranger'?"

"The eleventh planet in our solar system, also sometimes called Aucturn."

Odd name for a planet, but not all that much odder than fictional gods. "When you said you were retired from adventuring by the time you were able to reach other planets, did you just mean that you didn't want to travel for that long, or are they dangerous? Beyond the ordinary unbreathable air and storms and so on, I mean."

"Some of both. I run a university, which doesn't stop generating work just because I'm not there, and of course whenever I'm gone for too long my neighbors start getting ideas. The main reason, though, is that I try and avoid risks where I can, and while I'm sure there are places on other planets that would be safe enough to visit I don't know where they are."