OK sorry misread, OK a trillion FPS
I already basically answered this.
I say I have a hypothetical object travelling fast enough that it crosses the visual field in 3 or 4 frames or whatever.
And I choose it to be bright enough that it trips your rods and cones to create a visible light accumulation at every frame (say, a trillion times brighter than a typical object in the scene).
Now thats less than infinite, you're claiming we can tell the difference between 1trillion and 1triilion+1 FPS!
I never claimed that we can distinguish between proportionally tiny differences in framerate.
Although, if I'm allowed to use helicopter blade aliasing, I actually
could choose very specific rotor frequencies that would alias differently between those two specific framerates. For example, a helicopter rotor spinning at exactly 1 trillion Hz would look perfectly fixed in space at 1 trillion fps, but at 1 trillion+1 fps it would have a 1Hz rotation because of the slight offsets in position at the different frame samples.
google it theres lots of ppl saying there is a limit to the hz rate humans can see, yet I could not find a single person saying there is no limit.
Those people are addressing temporal resolution. I'm talking about light accumulating at spatially-separated regions over an accumulation period.
I'm not claiming that you can directly distinguish the high framerates in a temporal sense. For example, it would be basically impossible to distinguish between the 3 ghost images that occur in your visual system when viewing the super-bright bullet in the 1 trillion fps video, and 3 (less bright since they're displayed for longer) ghost images baked into a single frame of a 500fps video.
Link to me one single paper saying a person can see a flash of an incredibly short time.
Not sure about a paper addressing that exact question, but that's because researchers sort of take it for granted. When they ask about registering minimum visibility, they phrase in ways like
"what's the least number of photons that will register a visual response." Whether those photons enter the eye over a femtosecond or a nanosecond or a microsecond isn't really relevant, as long as they all enter closely enough that the sluggish responses given by our visual receptors are all in progress simultaneously. That's not the same thing as saying we can distinguish femtoseconds; if something high-intensity happened at femtosecond 1, and something else happened at femtosecond 5, we could see both, but we wouldn't be able to distinguish which order they happened in.
Photographers in more casual context certainly think that they couldn't make their flashes so fast as to be invisible, as long as they're bright enough.
The eyes accumulate light energy over a duration. Asking whether you can make a flash so fast that it's invisible is like asking if it's there's a duration that you can physically push an object for that's so brief that it can't move said object. If you halve the duration of pushing but double the power of the push, the object still gets pushed. If a ton of photons enter your eye over a femtosecond, it'll cause your rods and cones to flare up, much as it would if the same photons entered over a millisecond.