Is There Any Evidence for Other Universes With Gravity?

There are some cosmologists who have made up a particular models for the multiverse, in which other universes could collide with our own. And well, people have looked for the signatures of those other universes, and they haven't found any. So to the extent that those ideas were falsifiable, they have been falsified. But there's no reason why this guesswork should be correctis just not a scientific method of producing a new model.