Just watch them for a while.
I've been a cat-lover most of my life (for as long as I can recall anyway) and have spent a great amount of time serving and entertaining our moggy-overlords.
I've noticed things like when I'd rattle one of a couple of items, the cat would first glance at me - if the item was the laser pointer she'd then look at the nearest bit of ground or wall to her for the coming red dot, but if it was another item that had the same sound when rattled then she'd go to " normal mode" (ie completely ignore all humans unless providing treat or threat).
If you watch you'll see them judge distances before jumping, judge where moving objects are going to go (except those that don't act normally, like poorly made paper planes (honestly moggy, it was a mistake and not intended to confuse you!). I've even had one who would put her paw on the "hang up" button on the old school landline when I was paying more attention to the call than to her (fixed by turning the phone upside down) - watched her feel around for the button, look at the phone, realise it was out of reach so go back to sleep - I don't know how she learned that pushing that item ended the call but she did it several times each day from when she learned till I started turning the phone over - and she never put her paw near the area of the button when I didn't have the receiver in my hand) . I've watched them work out how to open a cupboard with a certain type of latch, and then use that knowledge to open a different cupboard with a similar-functioning catch..
But I don't agree that this necessarily means that they understand gravity, but more a sort of "cause and effect", which would be quite useful when hunting or stalking.
Certainly a functional understanding of some laws of physics, but maybe little more than "if I touch something hot I get hurt". They can, however, do a certain level of calculating velocity, trajectory, bounce, some levels of hardness and bendiness (see how they jump and land on cushions vs concrete vs small branch), and have effective knowledge of anatomy - like how to kill a smaller animal or just where to land on their owner to cause greatest pain/annoyance.
And they have an interesting level of logic as well. Much greater than politicians even.