linear: "It's turtles all the way down."
Continuing to Heaven, of course.
You might remember that our word "science" is short for the classical term "natural science", which derived from the ancients' "natural philosophy", meaning: finding natural explanations for natural processes.
Science can only exist where evidence of natural processes can be seen or inferred.
But where the natural realm ends, there also ends science, and begins something else -- beyond physics is metaphysics, beyond the natural is the supernatural, beyond science is philosophy or religion.
So, our FRiends linear & Pikachu_Dad assert (in jest, presumably) that's where turtles begin, but turtles provide only meager meals for our spirits.
Far better to visualize the End of the Natural Realm as the beginning of Supernatural Heaven, the place from which the Universe was Created and into which, presumably, it will eventually evaporate.
Of course, some atheists assert there is no "end of the natural realm", just the natural order continuing to infinity.
And it's your choice which to believe -- which do you think sounds more likely?
Please do not snap.
Turtles are not to be frivolous about. You might find yourself hoist on a fence post. And then you would be in the soup.
We all know that your hair is gone. Turtles will win the race.