[Verginius Rufus]

I've never read Newton's Principia. I know that he explains how gravity works--that every bit of matter attracts every other bit of matter. But did he ever explain why? Why doesn't matter just leave other matter alone instead of messing with it?

[Red Badger]

If the entire universe consisted of just two hydrogen atoms, a billion light years apart, they would eventually come together.

Gravity depresses the fabric of ‘Space-Time’ so that they eventually collide..................

[who_would_fardels_bear]

Most Natural Philosophers (scientists) at the time of Newton rejected his theories because although they seemed to work, he had provided no reason as to why they worked.

Much science is like that these days for better, and now more often, for worse.

[sergeantdave]

“I know that he explains how gravity works—that every bit of matter attracts every other bit of matter. But did he ever explain why?”

Jimi Hendrix explained it best -

Like attracts like, creating resonance until someone messes with the amplitude and it all gets blown up in a big bang, man.