Gravity- it’s known as the “weakest fundamental force”, but we know the “attraction” is really just objects falling along the curvature of space toward a more massive object. I don’t understand how this explanation of gravity relates to the other fundamental forces.
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A “force” is just a thing that causes an acceleration. In the EM field that thing is the exchange of photons. In gravity it’s the curve of spacetime. The underlying mechanism of a force doesn’t change that something is a force.
Ive always struggled with this too.
The best way I’ve seen this visualized is with a large rubber sheet stretched on a frame. Put two balls on the mat far enough away from eachother and nothing happens. You just have two balls on a rubber sheet making dents in the sheet.
Move the balls close enough and they will move towards eachother until they are touching and you have one larger dent in the sheet.
This is gravity in action. The mass of the two balls are now added together and their effect on the surrounding area has increased accordingly.
The dent in the rubber sheet is a representation of a gravity well, a curvature of space and time.
This however does not show the full picture, it shows gravity as existing in a single plane and implies a singular direction for the atraction. But when we look at objects in our solar system, they are not all in the same plane and we have objects that can orbit eachother at any 360 degree angle from their centre.
This is because space is 3 dimensional, and space isnt bending its stretching and compacting in all 360 degrees, and the degree of the stretch is a function of the objects mass, and the distance from the centre of the mass.
You can think of it like a weakening wave eminating from the centre, when the edges of two objects space distortions approach eachother and touch, their distortions interact much like a wave function. The degree of distortion increases at the edge as the wave functions add. That is, the space at their edges compresses and the objects become closer.
If a physicist is pedantic enough they absolutely will go out of their way to clarify that it’s not really a force.
But in all other contexts, the difference isn’t all that important. Certainly as far as the math is concerned, treating it like a force is way easier.
A lot of good answers, so I will try to summarize.
Classical (Newtonian) Physics: gravity is a force because it accelerate mass.
General Relativity: gravity is not a force. This theory very successful at explaining orbits, light bending around suns and galaxies time dilation observed on satellites around Earth.
Standard Model of Particle Physics: these guys are obsessed with particles and they want a particle for anything. Because of this, they are stubborn at insisting that gravity must be a force and we just need to find a particle (graviton) that carries that force. They also insist that it must be this way also because General Relativity doesn’t reconcile with Quantum Physics.
My understanding is that matter warps spacetime. This curvature is what we feel as gravity. However, many believe that there must be a force that bends spacetime. How exactly does matter warp space. Many believe it’s a force and the force carrier is the graviton.
It’s not. Gravity just “acts” like a force. So it’s really just an easier description for an otherwise complicated subject.
TLDR; Terry Pratchett called this concept “Lies to Children”, where adults simplify things to help kids understand, but simplify them so much they become factually wrong.
Basically, someone back in the day thought “This is too hard to teach kids” (probably because they are shit at being a teacher. Kids are way smarter than you think) and so said “Let’s just call it a force because it works like one. They can learn how it really works in middle school.” Then that looped until you only learn about it in college physics, if you take that…
This happens for almost everything, by the way. It also happens for political reasons, why is why you have grown ass adults who don’t think the US Civil War was about slavery despite the documents written by the south used to declare their independence literally saying “Fuck you, we’re doing this to keep our slaves.”
In everyday life, we still refer to gravity as a “force” because it’s a convenient way to understand its effects on objects around us. Newton’s law of universal gravitation, which describes gravity as a force of attraction between objects with mass, works very well for most everyday scenarios.
However, when we look at the universe on a larger scale or in extreme conditions, like near massive celestial bodies or at the speed of light, Einstein’s theory of General Relativity provides a more accurate description. According to General Relativity, gravity is not a force in the traditional sense but rather the curvature of spacetime caused by the presence of mass and energy. This curvature influences how objects move and interact with each other.
The other fundamental forces (electromagnetic force, strong nuclear force, and weak nuclear force) are described by quantum mechanics, and they operate differently from gravity. They have their own unique properties and are responsible for various interactions between particles at the atomic and subatomic levels.
So, while gravity is different from the other fundamental forces, we still use the term “force” colloquially to help us understand its effects on everyday objects, even though it’s more accurately described as the curvature of spacetime.
It can be both things at once. What’s the problem?
Easy, local observation, you can’t distinguish the two, so it is. This is why Quantum Physics breaks Standard Physics as well. At Human size level of observation things act one way, at Atomic size they act another and at Planetary/Galactic size, yet another.
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