Gravity Help

[Deathzilla7]

Now, I've taken Physics this year, and I am fully aware that gravity is a force that works by an inverse square law.

But, I want to know, is there ANY point at which gravity doesn't have an effect? Like, would adding a pinball to the centre of Andromeda and one to the centre of the Milky Way really have any effect? If they weren't added, but rather in a plane without any other matter, the same distance as what I stated above, would they REALLY have an effect at all?

Because, if you think about space like a sheet of paper or a blanket, yeah... it would bend around the pinballs, but the effect would end almost immediately after engulfing them. So, is there a, say "terminal distance" after which gravity between 2 objects ceases?

[atomic7732]

They wouldn't REALLY have any effect, but they would over a long long period of time (billions of years).

Gravity is infinite, there is no terminal distance as far as we know.

[Deathzilla7]

Hmmm...

I see.

Thanks.

[Bla]

Gravity "moves" (if you could say that) by the speed of light, so if it were magically added to the Milky Way now, the Andromeda Galaxy wouldn't notice before in 2,5 million years.
A single atom would have an effect, it's just a question about how big it would be.

[vh]

Really? i didn't know that before. I thought gravity was instant, it is in universe sandbox at least

[Bla]

Nothing that we know of is faster than the speed of light or instant.

But yes, in Universe Sandbox, a lot of things are instant.

[vh]

I was thinking, if you had a really long stick, one end of earth and the other on the moon, you could push it a bit to send some sort of signal, and whoever was on the moon would receive it instantaneously. ?

[Joshimitsu91]

Really? i didn't know that before. I thought gravity was instant, it is in universe sandbox at least

Yes, the fastest speed is c, the speed of light. All forces have their associated "particles/waves" which "transfer" the effect of the force.

Now, I've taken Physics this year, and I am fully aware that gravity is a force that works by an inverse square law.

Yep, and no matter how big you make r (or m1/m2), F is still > 0

[Bla]

I was thinking, if you had a really long stick, one end of earth and the other on the moon, you could push it a bit to send some sort of signal, and whoever was on the moon would receive it instantaneously. ?

Nothing happens instantaneously, not even if the stick was one meter long. To you it will seem instant, because you don't notice changes over nanoseconds or other very small amounts of time.

[atomic7732]

Yeah, the stick would probably compress from the pressure from the force of pushing it forward.

[Arnstein]

I don't know anything about this kind of thing(yet), but I recommend everybody to check out Khan Academy. On that site you can see videos about physics and maths and history etc, and you can even do math exercices!

Here is the physics playlist:
http://www.khanacademy.org/#physics