Did Newton and his contemporaries take the fact that gravitational acceleration is the same for all masses for granted?
I mean let's pretend masses don't "generate" gravity like newton thought. If you released two metallic objects of different masses near a giant magnet they wouldn't necessaritly accelerate towards it at the same rate because their resistance to acceleration is not the same as their magnetic attraction because they're unrelated.
Why didn't they see that it's too much of a coincidence and a convenience for gravitational mass to "just happen" be the same as inertial mass unless they are the same thing?
Why did Newton introduce gravity as just another magical force like magnetism and everybody just accept it? Doesn't this go again occam's razor? What would be the probably in nature that two completely unrelated things just cancel out?
>>7725132
that's not what I meant at all. You can replace magnetism with any magical force. Just to show that having two unrelated things happily canceling out is too much of a coincidence.
Could you be a little more specific what you mean? I don't really understand what you are saying here exactly.
As far as I know Newton didn't propose that all masses feel the same acceleration in the same gravitational field.
Newton's law of gravitational force (equation A) states that 2 interacting objects feel the same FORCE much like 2 electromagnetically charged objects (equation B).
However the acceleration itself can be calculated from the Newton's second law of motion (equation C) where we see that acceleration is same with the 2 objects that feel the same acceleration only if they have the same mass:
> F = m * g <=> a = F / m
> Let there be 2 objects interacting in a way that they feel same force m1 * a1 = F = m2 * a2
> It follows that a1 = a2 only if m1 = m2.
> QED
Same way you can see that in the gravitational field of one object 2 objects can feel the same acceleration only if they have the same mass (and distance).
I'm starting to believe that you have confused gravitational constant G here (about a scale of 10^-11 and is in units of [N m^2 / kg^2]) with the free-fall acceleration (scale 9.8 [N/Kg] or [m / s^2]), which is used in the motion-equation (C) to approximate the accelereation objects get in the free-fall of the gravitational field of the earth.
To be fair they are both often marked as G.
If your question was why free-fall acceleration is often approximated with a constant even though it should depend of the mass of the falling object the answer is 'because it's easier'.
On the other hand I don't know if Newton ever made this approximation...
But if you meant something else please do correct me.
>>7725393
Me again. Had a little slip there:
>However the acceleration itself can be calculated from the Newton's second law of motion (equation C) where we see that acceleration is same with the 2 objects that feel the same FORCE only if they have the same mass
>>7725393
Newton thought of the force that pushes back when you pushed against something as "fictitious".
He didn't think of gravity that way at all.
Gravity to him was just another force that masses "generate".
Like the suction "generated" by a vacuum cleaner or the pull "generated" by a magnet or the "foo" force generated by object "bar". He wasn't particularly concerned with the mechanics of how mass generates force. It could be magic. He just assumed it does.
He thought it was an unrelated concept with the degree to which mass resists acceleration.
Why didn't it bother him that these two unrelated (as far as he thinks) things just happen to have the same numerical value as far as experiments show.
>>7725400
So you're saying that Newton didn't think gravitation as a force?
I have never heard about anything like that but the easy answer could be that it just didn't occur to him. Many things seem obvious to us today but that's because we are told them in a understantable manner from a reliable source. Someone had to be first.
I'm sorry if this isn't what you meant either. It's getting pretty late here and I have last exam before holidays tomorrow. I'm not just in a right mindset to get this right now. And I'm off to bed now.
Keep this thread alive though!
I try to return tomorrow. I hope you get your answer OP.
Is there any actual proof of gravity as a force? The widespread assumption is that it's a force transmitted by quanta as per the unified forces, but I have yet to see any actual proof of that idea.
>>7725762
I haven't seen anyone trying to proof that but wikipedia says "a force is any interaction that, when unopposed, will change the motion of an object."
I think we have just defined force in a way that gravity fits it.
And I think that "transmitted by a particle" is actually one to win if we would use occam's razor (I assume) as all the other fundamental forces are also transmitted by particles. It just seemes easier that we have same way working forces than one that's so different from others.
i think mass is a property that resembles likeliness of existence. the more massive something is, the more likely it is to exist.
gravity in that model would be the rule of motion of possibilities to add up into certainty. there is still a lot of quantum-mechanical uncertainty in massive objects, but less than in a vacuum.
Stop posting this shit thread.
>>7726358
I would agree that force particles is the best way to look at it, but unfortunately that doesn't tell us a whole lot. We know very little about the graviton.
