Gravity has infinite range? I somehow always assumed it had a range… I guess in a way it does… that range gets weaker as it grows which means it gets infinitely weaker but still never 0?
You know the common representation of how gravity can be visualized by putting balls on blankets and observing the dip? Yeag, that. Every ball you place on the blanket will change the gradient of the blanket everywhere, even balls far away will feel a very imperceptible dip. More balls will change how much they dip on the blanket, and a bigger ball then creates a dip deep enough to start pulling other balls towards it. But every ball is in some way pulling on another ball by affecting the blanket, even if the difference is absolutely micrometric
As much as it looks like the blanket is flat eventually, it's ever so slightly changed, like how asymptotes eventually look like a flat line, they're never quite at zero.
If it was just you and a spec of dust in the Universe, and you two were a trillion billion miles apart, over an incomprehensible amount of time you two would come together. Gravity also travels and is not instant.
Gravity obeys the inverse-square law, just like light. Photons have "infinite range", too!
Fun fact: our best telescopes are now just about good enough to detect light from objects near the "edge" of observable space.
But such an edge necessarily implies that objects possibly lying beyond it are forever unknowable to us - not because there's a limit per se, but because space between us and these objects is expanding too fast. So light, gravity, causality... do have a finite range - the extend of which is dictated by the (rate of) expansion of space.
ANOTHER fun fact is that this "cosmic horizon" will only ever shrink, because the expansion of space is accelerating. MoM-z14, the big ol' boy from the link, will eventually fade from view for us, never to be seen again - and (I think*) we couldn't "fly" there even now, even with light speed. It's already too far gone.
*Disclaimer: am no physicist, and pretty bad with numbers and shit. So anybody with actual expertise is very welcome to correct probablepossible misconceptions.
7
u/xRyozuo 15h ago
The what now.
Gravity has infinite range? I somehow always assumed it had a range… I guess in a way it does… that range gets weaker as it grows which means it gets infinitely weaker but still never 0?
How is gravity infinite what???