If something is inbetween two objects how do the particles know there is something bigger behind the object it needs to attract to?
In: Physics
Well, particles don`t really “know” to attract to other particles. What happens is that matter bends space in such a way that makes other matter fall into it. This goes both ways of course, so objects with mass keep falling towards each other.
A great and simple way to imagine this is through this video https://www.youtube.com/watch?v=MTY1Kje0yLg
The video shows this happening in two dimension, but basically the exact same principle applies to three dimensions.
A good analogy for gravity is putting a bowling ball on the center of a trampoline
https://blakedynasty.typepad.com/.a/6a0120a6ef4079970b0120a7f14ec2970b-pi
the bowling ball sinks into the ‘sheet’ and any other balls you put on will roll towards it.
No matter where you put other balls – near to the bowling or farther away – they’ll always roll towards the bowling ball.
and also if you have lots of balls inbetween the bowling ball and the edge of the trampoline, they all still roll towards the bowling ball at the center.
so – with the huge sun at the center of our solar system, all the planets are affected by it no matter whats in between.
What we perceive as the Force of Gravity is actually a warping of Space-Time produced by the presence of “*Things*”. “Things” in this context are Matter, Energy, and *maybe* some other things we don’t know about yet. If it **occupies** Space-Time, then it warps Space-Time.
Space-Time is the Space and Time that *Things* can occupy in this universe. When Space-Time is warped by the presence of *Things*, a *bias* is introduced into how *Things* move through that warped Space-Time. Objects will move towards the *Thing* that is warping Space-Time, unless they have reason *not to*. You experience this as Gravity.
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The warping of Space-Time has some funky properties.
The Warping is at its most intense where the Thing is, and falls off relatively quickly… but never ceases to have an effect. This is the reason we have Ocean Tides on Earth. There are three sources of Gravity that are strong enough *on Earth* to affect the oceans: Earth, our Moon, and The Sun. When the Moon or the Sun is overhead, the gravitational bias changes enough that the oceans are “stirred up” by the small change in their weight.
The Warping produced by multiple *Things* located in the same place will “combine” to produce an aggregate effect larger than any one *thing* could manage. That’s why celestial bodies have Gravity Wells. The weight of any one grain of sand isn’t much, but the weight of the entire Earth and everything on it creates a Gravity Well that holds the whole thing together (and forces it to a roughly spherical shape).
> Weird Side Note: Gravity goes *weird* at the center of a Celestial Body. It you stand at the Center of Mass for a Planet… you’d probably experience something similar to Zero Gravity if it weren’t for the intense pressure of everything *else* being pulled towards you.
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With that groundwork in place, we can answer your question.
> If something is inbetween two objects how do the particles know there is something bigger behind the object it needs to attract to?
This is the weirdest thing about Gravity to wrap your head around. Every other Fundamental Force has what are known as “carrier particles” that move information around. Gravity, as far as we can tell, *does not have a Carrier Particle*.
Gravity-Related Information is not directly shared between Particles… it is instead indirectly shared through the aforementioned warping of Space-Time. The particles don’t need to communicate, because the information is stored in the medium (Space-Time) they occupy.
The only way to affect the strength of a Gravitational Field is to either shove more *Things* into a space, intensifying the aggregate warping effect of that mass; or you need to take *Things* out of a space… spreading that effect out.
You’d need something theoretical like negative-mass that pushes outward rather than inward to counteract gravity. The thing is, something like that would require a lot of energy even if we somehow had negative-mass readily available. Then you have the problem of being unable to control the direction of this mass. For example, if you wanted a hovering anti-grav car, nothing is stopping the anti-grav from pushing normal objects around it in every direction. It would be kind of like when a helicopter pushes everything away with the rush of air from its blades, but worse, because it’s also pushing up and to the sides in all directions instead of just down.
The best we can currently do is magnets, which is a different force that can locally push up against gravity. Thing is that’s limited to rails, so the future is electric maglev cars on rail unless we discover some new physics breaking technology.
The other explanations here are not really getting at the heart of your question (which isn’t any different for gravity – other forces do the same thing).
Your error is in going “this is a solid object and nothing can go through it”. But what you think of as “solid objects” are not completely impenetrable. As an everyday example, light has absolutely no trouble going through glass.
[EDITED to clarify: this part is here to explain to OP how their idea of ‘solid’ is inaccurate. It’s not directly about how forces can go through things] ~~’Solid’ objects don’t fill up all the space in the region they occupy (in fact, they’re not even *close* to filling up all the available space). They seem solid on human scales because electrons repel one another, so once two atoms get even somewhat close, they’re pushed apart by the repulsion of the electrons in each atom.~~
On an even more fundamental level, fields (like the electromagnetic field or, if you set aside some of the weirder aspects of relativity for a sec, the gravitational field) aren’t different things from the physical objects around you. Objects are “made of” these fields, in the same way that a wave in the ocean is made of water. What we think of as a particle is just a place where these fields take on different values from other parts of the field, in the same way that a wave is just a place where the water is a little bit higher. And so your question becomes, roughly, “how can water travel through a wave?”.
If this seems strange, well, it is. There’s a reason it took fifty years and some very surprising experiments for the most brilliant minds in physics to figure it out.
Gravity isn’t pulling on stuff like magnets or a vacuum.
It bends space and time. To block gravity, you’d need to bend space the other way. To do so would require an absolutely incredible scientific discovery, and is the basis for the hypothetical warp drive.
So, even though we live on Earth, and the Earth’s mass keeps us on the surface, do other bodies with a mass greater than that of the Earth (ex. the Sun) affect us as well? Even a tiny bit?
I feel like a lot of the answers are presenting great theories, that are ultimately unproven and largely are just describing how we know things act.
The truth is, we don’t fucking know. We just don’t know a lot about gravity, what it ‘is’ and how it functions.
We know it has a pulling force, it acts broadly based on size of object. And there’s theories it fits nicely into for equations and working things out by maths.
But there’s a whole lot more we don’t know about gravity…yet…
Well, depends on what you mean by blocked or dampened.
Let’s look at heat here. Heat, just like gravity, is type of energy. It behaves a bit differently when it comes to exact science, but for our purposes it works fine.
How do we dampen or stop heat? We put something between heat source and what we want to stop from getting heated up. Heat dissapear? No, it gets absorbed into the material we used as a heat shield. Same with removing heat from object. We coat it in something that has low heat and well tranfers heat itself like water. The heat dissapears, it’s just divided between more matter, so original matter has less of it.
Similarly is with gravity. We can damper it by putting a force between two object that attract themself by gravity. That’s how we achieve flight. We create enough force to stop gravity. Like heat before, gravity doesn’t dissapear, it just is counteracted.
The only major difference is that we cannot really stop creation of gravity like we can put out the fire. Cause fire is a chemical reaction that generates heat. We can stop that reaction. But gravity is generated by existance of matter itself. And removing matter from existance is way harder.
But to shortly answer your question: we can damper gravity. That’s what wings and engines on planes do. That’s what you do for a short moment when you jump. Or even when you just stand. Your legs damper gravity enough so you aren’t crushed into the earth beneath you. There’s just a lot of gravity created non-stop.
Why is it every time I visit this sub, nobody knows how to simplify it to honor the sub’s name?
[This video helps](https://youtu.be/MTY1Kje0yLg)
It’s not a complete definition of gravity, but it’ll help you understand.
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