I designed how Gojo's open barrier UV changes the effect (Discussion, lengthy, TL;DR at end)
This was made as a comment on a recent post in the sub, but someone recommended I make it into a post and turn it into a discussion.
Manga spoilers are put in the proper spoiler tags, and they are few.
How would Gojo's open barrier UV work, and if we had to design it, how would it be fair?
An Open Barrier Domain grants increased range, and an immunity to attacks against the barrier which would crumble the domain, because such a barrier simply doesn't exist; with the trade-off of an escape route for victims, and in some cases, a weaker effect.
Sukuna's domain, Malevolent Shrine, is a domain that has a specific output of slashes it throws at those in its range, and while this output is usually too great to defend against at all even from some Special Grades (Finger bearer) it is STILL a capped output with a theoretical resistance you could have being enough to withstand the slashes. Manga spoilers: >!We saw this in its inverted from, where Sukuna was weakened, instead of the main cast and raiding party on Sukuna being far stronger than a normal Special Grade, where we saw grade 1 sorcerers tanking a weakened Malevolent Shrine.!<
The method of defense was always obvious - it's a physical attack, though invisible, and you defend yourself with CE reinforcement (which you could localize if you had great reactions and saw Sukuna's slashes, but unfortunately only Yamata no Orochi and Mahoraga could ever see his slashes, and we don't know if they tried localizing CE reinforcement),
as well as Reverse Cursed Technique.
However, this is different in the case of Domains like Mahito and Gojo. UV attacks the brain in a non-physical manner, and SEoP grasps the soul. (I do not remember if reinforcing your brain with CE was ever proposed as a viable defense).
These attacks cannot be defended against with classic CE reinforcement, but they too have an output.
Mahito's Idle Transfiguration, which is the same technique embedded into his Domain minus the need for direct palm contact, found its limit when he encountered Sukuna, who exerted a greater force over maintaining the shape of his own soul, than Mahito did in transfiguring it. This wrestle over control was not even a wrestle, so Mahito's technique definitely had a limit.
To get to Gojo,
The effect of Unlimited Void is one Gojo does not have access to outside of the Domain, unlike Mahito, but this effect too has an output which was measured at 6 months of information per 0.2 seconds in its occurence in Shibuya, and not to complicate it, let's assume this is the going rate no matter how long the Domain is open for, and that UV doesn't have a warm-up (so let's assume this wasn't a reduced feat by Gojo in order to maintain control over it and be able to stop it within 0.2 seconds),
so it would equal 2.5 years per second as the standard output rate of UV.
Unfortunately, even Sukuna's Domain is something basically no one can defend themselves from, but it's a type of attack they have the tools to defend from, even though the output is insane.
But factoring in the nature of Gojo's attack, adding in the output, makes it completely unfair.
It's not just that the attack is insanely strong, it's that even if it were far weaker, no one could defend against it, so an open barrier would have to work differently in order to be made 'fair', but since the ability itself is unfair, making an open barrier UV fair to how fair MS is (somewhat, somehow barely defendable, and not an absolute overkill beyond overkill) should give it a strength of a few seconds of additional information per second of time, and depending on if that number is 3, or 20 s/s, the range could be greater or lesser than MS's 140 meters radius.
So let's get into the design of a potential open barrier UV.
I imagine an open barrier UV would work in terms best explained as 'strength of static'. If normal UV just makes your TV (mind) go full static, being further away from Gojo, or the center of the Domain, depending on how he constructs it, should disturb your mind less.
A way to make an open barrier fairwould be making it so yu're flooded with a lot of information, but not '2.5-years-per-second' type of a lot.
However, let's assume an insanely weak output of UV. If it were just 1 second per second, you're intaking twice as much at once, which should probably tire you out extremely fast,
and imagine how close to the edge of 0 effect you have to be to be inflicted with just 1 second of info per second, on top of your already 1 second of info per second you get from just living normally, and that's close to damaging you.
If we assumed the strength of the domain fades linearly from 2.5 years right in the centre to 0 at the exit, the domain would still be genuinely unfair.
Assuming a 1km effective range, but nowhere close to 2.5 years per second, you'd be hit with 10 seconds per second at less than 0.1 meters into the domain's effective range, and at that point you can probably only focus on the simplest of tasks, such as running and barely making out where the ground in front of you is, and which direction is further away from the thing causing your mental overstimulation.
When you imagine how many seconds are in 2.5 years, you slowly realize exactly how an open barrier UV HAS to work, since that amount of seconds cannot be split linearly, and since Jujutsu laws and binding vows strive for fairness.
Realistically, if the technique is to be fair, the drop off must happen either very close to where the normal barrier would be since, as we just said, even the slightest fractions of 2.5 years per second are terrible enough to incapacitate any brain;
Technically, Gojo could also lower the output of the entire technique to fit the greater range and the open escape route (a boost to his options), but even a 2 week per second everywhere in the domain is a terribly overpowered ability. Eating a day of information in less than 0.1 seconds is crushing you. It's only the fact that it lasts 0.1 seconds that it isn't putting everyone into a coma, not the fact that 1 day of information is not a lot.
Important thing to mention,
if what caused everyone to pass out in Shibuya was the fact they gained 6 months of 'memories', not 6 months of 'current, present moment' type of information of a gibberish, randomized, incoherent nature (of which I always assumed the latter was the case based on how Jogo explained it),
then 1 day of 'memory' is not that bad, because it's only a few more key points of one day appearing in your mind at once, not a Light-Yagami-in-helicopter type of moment, and the entire powerscaling of this comment in terms of information is then meaningless.
The fact there should be a drop off, and a non-linear one at that, also reminds me of Gojo's Infinity defense, which utilizes a concept from mathematics, a limit, but I didn't get an idea on how to incorporate a limit into making an open barrier UV fair.
If the mathematical limit of the strength of UV was concentrated at the outermost part of the domain, at where the effective range faded, and the strength approached 0 additional seconds of information per second, that wouldn't make a lot of sense, because just a bit closer in the Domain, you're still fucked. Actually, it also depends on which number / rate the center of the domain, the series, starts from.
But you could oppositely frame it as a series heading towards a limit which is situated in the center of the domain, where the limit approaches the value of infinite information per second, but both the starting value of the series, a1, and the shape of the graph of the function (of the series) still matter, because if it's exponential, then it's fair, but if it's logarithmic, then at halfway between then center with max infinite output and the edge of 0 effect, you're still getting absolutely destroyed by an output worse than 2.5 years per second,
but still, these are propositions instead of 2.5 years per second spread out homogenously throughout a Closed Barrier UV.
As I now conclude this section with limits, I realize it has nothing to do with limits, and could have just been a talk about functions. Silly me.
TL;DR
An open barrier UV should drop off in strength based on how far you are from the center of the domain (or from Gojo, depending on how he chooses to design it), by delivering less information per second to the victim.
Gojo's UV effect is not a physical attack like Sukuna's, and is therefore additionally undefendable from, on top of its 2.5 years per second (6 months per 0.2 seconds in Shibuya, only output rate ever explicitly given) being too strong on its own. Even in its weakest hypothetical forms of 10 seconds of information per second, victims are experiencing 11 times as much information at once, and unless reinforcing the brain with CE does anything, you can only hope to shut your information intake by killing your senses, unless UV delivers it all straight to the brain as you are inside UV's space,
so it is only manageable within tankable ranges of output (less than 5 to 10 seconds of information per second)
Because of that, the function of the rate of strength compared to distance from the edge of 0 effect towards the centre of the domain (or the distance range between farthest edge of any effect and center) cannot be linear, but must be exponential
(or better yet, superexponential, or better yet than that, just
a^(x-b)+c,
where the greater b is, the closer to the centre of UV does the effect become substantial,
and the greater c is (c>0), the stronger UV is in the part where it shouldn't be too bad).
This is done as so, because, as said, anything more than 10 seconds per second is knocking you out. That's the only way to make it cool, and fair, and have an opponent experience the 'static' of information overload and experience 'losing their mind', without having had instantly lost it.
There we could have someone experience shit like in S.T.A.L.K.E.R, where the effect is there, but hasn't taken you completely at once and turned you into a vegetable.
I also just don't see the radius growing linearly, because for 2x radius, Gojo splitting the effect's strength in half is still 15 months of information per second which is basically the same shit. He'd have to reduce it to mere seconds or minutes per second to actually be fairly granted a significant increase in range for his Domain.
so
What do you think, how should Gojo's open barrier UV's effect work, and what should the range be, given Sukuna's is 140 meters (though that one is an output of physical attacks)?