Possibility (there are serious scientists who consider it a likelihood):    A massive star imploded into a black hole. The result was a Big Bang and another universe began. Us. Here. And in our universe, every time a massive star implodes into a black hole, another universe starts. And they, in turn. . . .

And, of course, the universe from which our universe sprang was created the same way.

Big fleas have little fleas
Upon their backs to bite 'em;
And little fleas have littler fleas,
And so ad infinitum.

And then there is the little matter of eleven dimensions. They're right here, but we're able to perceive only three, and have a sense of the fourth.

All of which boils down to this:   hard-headed "realists" shouldn't necessarily be so phlegmatic about such things as paranormal phenomena. They might be "leakage" from other dimensions.

(Cue Twilight Zone theme.)

Don Firth