You need energy to produce a force that compensates gravity. So if you apply that force for a huge amount of time, will gravity ever be depleted?
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Force is cheap. Energy isn’t. They are not the same thing. Dropping a rock from high up to a lower position in a gravity well converts potential energy into some other kind of energy (maybe one you can use). But a rock exerting pressure on a table, regardless of how much pressure or for how long, is not an energy transfer.
While gravity is not free energy, you can be smart about it. There is an electric dump-truck that never has to be plugged in. It drives uphill unloaded, gets a load of material, then drives back downhill. The use of regenerative breaks with the heavy load charges the battery more then the amount needed to drive back uphill empty.
https://www.greencarreports.com/news/1124478_world-s-largest-ev-never-has-to-be-recharged
The universe has zero sum energy. You can think of matter as positive energy and gravity as negative energy (analogy only, negative energy is hypothetical). As matter is created, a gravity well is also created. To have no gravity well means no matter.
Something I haven’t seen pointed out here yet. The effect of gravity isn’t exactly a force. It used to be considered one of the 4 fundamental forces. Not anymore. Rather, it is the bending of Spacetime caused by mass. If you shot a bullet in space, it would just keep going straight. If you do the same on earth, the bullet would still think its going “straight” and in essence it is. It’s world line just to happens to be curved from an outside observers perspective.
What you’re talking about is force. But force doesn’t to *work* unless it moves a distance. and *work* is energy. If there’s no movement, there’s no work done, and thus no *energy.*
It requires a certain amount of *energy* to move two objects in the opposite direction of their gravitational pull (pull them “apart”). If you allow those two objects to return to their original positions, they will “release” the same amount of energy which was consumed to separate them in the first place.
You’re assumption seems to be that, in order to *maintain* a force, *energy* is being *consumed (*in the same way you get tired if you push on a wall for long enough)*.* this is the disconnect. Energy *will ONLY* be consumed or released when that force begins to move, and do *work.*
In the case of your body getting tired pushing on a wall, or say, holding a book up in place, your body *is* doing work – but not on the wall, or book. This is because your muscles actually are moving on a microscopic level. you can never actually stand perfectly still, and your muscles and skeletal structure sort of “ripples”. This ends up consuming energy and rejecting it in the form of heat for the most part. There is also some chemical reactions at play where energy plays a role in the reaction but i’m not well versed enough here.
By analogy, if you had a pressurized cylinder with a piston, and allowed that piston to press on the wall with the pressure of the cylinder but the wall did not move – that piston would continue applying force forever without any additional energy input. this is also true if you replace the gas cylinder with just a spring.
Forces don’t require energy. Ever. It does however require energy to change an objects position, which requires a force.
As long as nothing changes, then there is no need for energy to be transfered.
From what I understand, energy is not a “force” it’s just a deformation of spacetime, so, there’s no “amount” of gravity to deplete.
From what i understand, gravity is the result of matter bending space and time.
The force creating gravity is therefor matter.
So planets and stars are the force that is creating gravity.
I personally do not totally believe in this exact theory myself.
Einstein came up with it.
The short answer to your question is “No.” But what’s really going to screw with you is that gravity isn’t a force – there actually is no such thing as a gravitational force (as we understand it today): [https://www.youtube.com/watch?v=Xc4xYacTu-E](https://www.youtube.com/watch?v=Xc4xYacTu-E)
Gravity, in our everyday human experience, is merely a notional model of reality. It’s a useful model, but it’s not what’s “really” happening.
So, gravity isn’t an endless energy force (actually, it’s nothing, but part of a model of behavior). When energy is expended to change an object’s position, velocity, acceleration in space-time, that energy isn’t working against or compensating for gravity.
The full explanation is a bit complex, but I will try to simplify it a bit:
I am assuming that you mean that we could, hypothetically, extract energy out of Earth’s gravity. To do this, you need an object above the surface of earth in a high place.
Let’s say you have a baseball that is placed one meter above the ground. This baseball has more gravitational energy than if it were on the ground. However, in order to extract that energy, you need to make the baseball fall down from its high place and onto the floor, and while it falls down, you need to transfer some of that energy into a motor (by colliding the ball onto a paddle that moves the motor, for example), and then transform the movement of the motor into something else (technical stuff that is not important right now). But once the baseball reaches its minimum height (the ground), then all the “gravitational energy” is already depleted, and is usually dissipated onto something else (transformed into heat, usually).
This is the basic principle of hydroelectric power plants, because water can be see as “a bunch of baseballs” that are falling down from a high place following a stream due to Earth’s gravity, and we simply use motors attached to paddles that collect a little piece of that energy.
However, in order to collect that energy, you need an object falling down from a high place (water/baseballs), and in order to get those objects back up, you need to invest energy in carrying them above the ground (you need to put the baseball on top of the shelf for it to be able to fall down), and that usually requires more energy than what you usually can harvest when if falls back down. In the case of water stream, what makes the water “rise above” is its evaporation because of the heat of the sun (and the water cycle, that later makes it rain). So in a sense, hydroelectric power is just gravitational energy harvesting powered by the sun.
So, to summarize, gravitational energy is associated with the height of an object, not the force that pulls it downwards, and it can only be harvested when the object moves downwards, so it is impossible to obtain unlimited energy from gravity.
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