Why is there Gravity?

Question

I was inspired to ask this question by JavatheHuntsman's question. He asked why we don't fall of the earth. Of course everyone then proceeded to make fun of him. But seriously, Why don't we? Sure we know about Gravity, but where does it come from? WHY is there even such a thing as Gravity? I know that Gravity supposedly can bend time, so it it a byproduct of time? Or is time a byproduct of gravity? Or are they maybe both smaller components of some other force that we don't really understand? I'm really looking forward to the day when scientists have this all figured out. It's interesting! Please add in you theories/speculations or even fact. Thanks.

Answer 1

i think since we can't precisely answer the question " why is there something rather than nothing?" we can't answer the question " why is there Gravity?" either. But where does it come from? and what is it caused by? are questions that still have no precise answers and are being researched, maybe we have to wait for large hydron collider to give us some answers.

we can talk about gravity in terms of space time curvature and we can describe the mechanism and effects of gravity but the cause and source of it are still unknown.

Answer 2

Not everyone made fun of him.  I answered the question.  

"Gravity is one of the universal forces of nature. It is an attractive force between all things. The gravitational force between two objects depends on their masses, which is why we can really only see gravity in action when at least one of the objects is very large (like the Earth)."

"Isaac Newton was the first scientist to define gravity using math. There will be a larger pull due to gravity if the objects' masses are larger and if the objects are closer together.

One thing we can do with Newton’s law is calculate an escape velocity for the Earth. That is the speed something has to go for it to escape the gravity of Earth. This number for Earth is about 11 km/s.

In general relativity, the effects of gravitation are ascribed to spacetime curvature instead of a force. The starting point for general relativity is the equivalence principle, which equates free fall with inertial motion. The issue that this creates is that free-falling objects can accelerate with respect to each other. In Newtonian physics, no such acceleration can occur unless at least one of the objects is being operated on by a force (and therefore is not moving inertially).

To deal with this difficulty, Einstein proposed that spacetime is curved by matter, and that free-falling objects are moving along locally straight paths in curved spacetime. (This type of path is called a geodesic.) More specifically, Einstein discovered the field equations of general relativity, which relate the presence of matter and the curvature of spacetime and are named after him.

Answer 3

First, your (& that guy Huntsman's question). What is meant by 'falling'? It is to move down, in the direction of gravity. You don't fall up on the ceiling; would you? Wherever you are, in space for instance when you fall, it points the direction of gravity. If you don't get 'this' right, there is no point going any further. Unless this confusion is exorcised almost all astronomy goes (like those bodies viewed in the sky) over one's scalp.

Now, Universe exists whether you exist or not. Gravity is all the time there. You exist, I exist because of it, whether we possess the intellect to acknowledge it or not. Gravity is the brick & mortar of universe. We have come from (God knows) somewhere! All humanity is a 'guest' at the tiniest corner of universe for an insignificant fleeting moment. If this little piece of realisation is unpossessed it is called 'arrogance'. That being so, who the h**l are we to ask  such questions? Accept things as they come as Mother Teresa was fond of repeating.

But curiosity is one thing! These mysteries. Humans were given limited intellect and five doors (senses) that lead to the pathways to understand nature. Anything that does not enter the 5-fold human perception needs to be inferred by a laborious process that might consume a life time even called Science. Thus, nature's mysterious ways can be unraveled in a systematic way for which a host of mental (mathematical) tools are to be mastered before interpretations are possible.

Any force has ingredients one of which is time. Gravity is one of the 4 fundamental forces and is no exception.

Answer 4

Think of a giant cannon ball at the center of a very taut trampoline and then what would happen if you rolled a marble near it.

There is a two-way interplay between mass and spacetime.

Mass warps spacetime and that warped (and even unwarped) spacetime influences the 'paths of least energy' of smaller objects respectively.

Rough model, but should help you picture it better.

Answer 5

How do we calculate time? Usually, it is are position in space. One day is the Earth's rotation, and a year is one orbit around the sun. Those things happen because of gravity. I don't think things would exist without gravity, nor would there be any gravity without objects. Hope I helped!

Answer 6

you're thinking along some good lines.. gravity can be explained mathematically by the idea of spacetime- any event has a 4D coordinate (three space and one time), and the geometry of this coordinate system is affected by matter.

This "effect" is what we call gravity.

We don't fundementally understand it, and it doesn't work too well with some other scientific theories, but it's probably because we simply don't understand the "bigger picture" yet, which will hopefully unify some of our physics.

You said "gravity can supposedly bend time", this is a manifestation in the physical world of the process called gravity - matter bending spacetime.

it's very mathematical and you probably need a good maths degree to begin to understand the quantitative side of the theory.

Answer 7

think of it this way

space-time is a giant sheet, that expands infinitely in every lateral direction... every object that sits on this sheet puts a dent in it, this dent is what is believed to be behind what we call gravity. the bigger the object, the bigger the dent and thus the stronger the gravitational effect it has on outside bodies..

this is our BEST explination and it took one of the worlds GREATEST scientist to date to even begin to put it in a way that we can comprehend it.....

his name was albert einstein.