It may be worth it to decide how we define ‘unstoppable force’ and ‘immovable object’.
An Immovable Object has 0 velocity:
v = 0
Acceleration is the time derivative of velocity:
a = d/dt(v(t))
a = d/dt(0)
a = 0
And we know that
a = F~net~ / m
An object with infinite mass would satisfy this equation, but an object with no net force would too. We could add a correction force that will satisfy the constraint of 0 net force.
|F~net~| = 0
∑F~i~ = 0
F~correction~ + … = 0
To satisfy Newton’s 3rd law, we would need a reaction force to our correction force somewhere, but let’s not worry about that for now.
A physics definition of ‘Unstoppable Force’ is:
|F~unstoppable~| =/= 0
In this case the gravitational force fits this description, given a few constraints
F~g~ = Gm∑ M~i~ / x~i~^2^
As long as the gravitational constant G is not 0, our object has mass, and
∑ M~i~ / x~i~^2^ =/= 0, then
|F~g~| > 0
But this does feel kinda like cheating because it’s not really what people mean by ‘unstoppable force’. the other way to define it is just immovable object in a different reference frame.
a = 0, |v| > 0
I’m gonna stop here because this is annoying to type out on mobile
ripcord@lemmy.world 1 day ago
OK, but being very massive is not the same as what was being discussed.
You can also “lift” a finitely massive black hole with anything else massive.
Cocodapuf@lemmy.world 1 day ago
Are you sure? I mean the word “heavy” was what I was going on, but there is a distinction I suppose.
Yeah, that’s true… But again, I do have to stress that there is no alternative to “finitely massive” you really can’t have an object of infinite mass in our universe.