What do we know about gravity? Basically, we know that everything has gravity, and a certain amount of material has a certain amount of gravity, whether it's mass, or energy. However, every single speck of dust in the universe has gravity, which affects the measurements of the gravitational pull of every other speck of dust.
This article aims to ask the question what do we really know about gravity? Answering is a different matter, because some astrophysicists think they know a lot about gravity, when in reality, they probably don't.
Everything has gravity, both mass and energy, and the amount of gravity in one kilojoule of energy is equal to the amount of gravity in one kilo of mass, divided by the speed of light squared.
Newton's law of universal gravitation states that the force of gravity exerted by two objects is proportional to the product of the two masses, and inversely proportional to the square of the distance between them.
This is called the gravitational constant, and it's used in many calculations to try to hypothesize things in astrophysics. The problem is, it can't really be used to figure out anything, and may in fact be wrong.
The reason is that every single speck of dust in the universe has it's own equation, with every other single speck of dust in the universe. We are sitting in the gravitational well of our sun, and then the galaxy, and then the universe, which affects the amount of gravitational pull that objects have on each other.
Let me be clear, the amount of gravity remains the same, but the actual amount of pulling power changes for the same amount of mass inside a gravitational well, because there is the opposing force of gravity on every side.
The escape velocity of the earth in a complete void would be much greater than it is now, because there would not be any help from the gravity of the stars, planets, space dust, dark matter, and dark energy on every side.
In order to maintain a steady orbit of the earth in a void, you would have to be much further away from it's gravity, or moving a lot faster, and the gravitational pull would decrease in a more gradual curve than it does with the earth where it is now.
The same would be true of the change in gravitational pull in large patches of space where there isn't much of anything, such as inbetween galaxies, and close to the edge of the universe.
What Do We Know About Gravity?
In order to figure out how much gravity the universe has, you would have to be able to measure all of the mass and energy in the universe.
While scientists say they have measured this accurately, it's based on calculations of the temperature they think the big bang was when it happened, and the rate at which they think the universe expanded.
I personally don't think they know enough to accurately calculate the amount of material in the universe, and even so, it isn't just gravity that affects the movement of the universe.
There is this unknown thing called dark energy that pushes the expansion of the universe, making it accelerate in it's expansion, rather than slow down, (like it should), because of gravity.
Dark energy and dark matter themselves have gravity, and there is no real way to tell how much of either there is, because one pushes, and the other one pulls, but the one that pushes also pulls at the same time, (due to gravity), and we don't know how much it pushes, as compared with how much it pulls.
Basically, we don't even know how much gravity there is in the universe, we can't see 99.99% of the universe, and the gravity of the universe affects the measurements of the gravitational pull of objects, based on how close the other objects with gravity are to it.
For example, the distance we are from the sun affects the amount of gravity on both the facing side, and the opposite side of the planet slightly, but this is mostly counteracted by the gravity of all the stars on both sides. We can see that the moon moves the ocean, and this effect is most noticeable because it's so close.
I could go on, but while gravity is infinite in it's reach, my knowledge of the subject is limited, same as everyone. What do we really know about gravity? What goes up, must come down, and that applies to everything in the universe.