Can gravity make gravity?

Mass distorts spacetime: this distortion is gravity.
Energy equals mass time the speed of light squared.
If matter and energy are equivalent/interchangeable, then energy can create gravity, too…yes?

In this thread,
Could gravitational waves be an alternative to dark matter or dark energy? - In My Humble Opinion - Straight Dope Message Board
Chronos describe how two black holes merging released several suns’ mass worth of gravitic energy.

Is gravity borne/begat by gravitic energy a thing in General Relativity?

In the galaxy, could gravity begat by gravity explain Dark Matter?
In the massless voids between galaxies, could the lack of mass, gravity, and “begotten” gravity explain Dark Energy?

Not a physicist but IIRC it does create gravity; it’s energy and energy distorts spacetime like matter does.

But no, it’s something long known and can’t explain dark matter or dark energy. Both because it’s not a big enough effect and because it was an already known effect before those issues came up.

@Der_Trihs has the right of it. Gravity does, itself, gravitate (though as you can imagine, in any situation where this actually becomes relevant, it’s a bitch to calculate it). And this doesn’t explain dark matter nor dark energy.

Have you heard of a kugelblitz?

More fun with kugelblitzen: Imagine you’re in the center of one, as its forming. Since the incoming radiation that forms it is moving at the speed of light, you won’t know about it until it reaches you. Which is after the time at which it forms the event horizon. Which means that it’s possible to cross an event horizon without having any knowledge at all, even theoretical, of that as it’s happe

I fear the worst for @Chronos, crossing the event horizon mid sentence.

Which means that it’s possible to cross an event horizon without having any knowledge at all, even theoretical, of that as it’s happe

I see what you did there. :wink:

IANAP, but this seems to be just trivially true, since energy and mass are indeed interchangeable. It’s just that, in our everyday terms, it takes an incredibly enormous amount of energy to have any measurable mass, and conversely, very little mass to create enormous energy.

Quote from Wikipedia:

And AFAIK there never can be, as the only discernible properties of a black hole are mass, spin, and charge. By definition of an event horizon, no other properties are observable, so “origin” information is unknowable.

That’s a band name if I ever heard one.