What is Gravity ?

What is Gravity ? Everybody would say "It is the force the Earth exerts upon us so we do not go flying off into space by centrifugal force". Not scientifically good enough.

Newton's law of universal gravitation states that any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between the two bodies.

Newton`s 3rd law of motion states ;-
For every action there is an equal and opposite reaction.

Is that good enough ? No.

Why does an inert mass possess an inherent gravitational force and how is this force generated from gaseous or rocky material ? Where does the energy come from in an object which is not capable of generating a force?

After all, masses are just masses and forces have to be generated : F=MxAcceleration, so where does that leave all the many Trillions of bodies which comprise our Universe in conforming to Newtons 3rd law of motion ?

Gravity still remains one of the biggest mysteries of physics and the biggest obstacle to a universal theory that describes the functions of every interaction in the Universe accurately.

If you think you can shed some light on this, please post your comments.

[Ramrod]

It is hypothesised that the gravitational force is mediated by a massless spin-2 particle called the graviton

Originally Posted by Ramrod

It is hypothesised that the gravitational force is mediated by a massless spin-2 particle called the graviton

The graviton is a hypothetical elementary particle that Quantum Physics cannot prove even exists - it is a pure theory.

IF gravity is the result of gravitons, then it is not the answer until proven and that is a long way off. It is currently just an idea. So in that respect, it is one of sciences unknown features, hence my final posted comment concerning gravity being a mystery of modern Physics.

There is no gravity - the Earth sucks.....

[Stephen]

Dunno, but its heavy man!

[cookie_365]

As ever, Philomena Cunk has the answer

https://www.youtube.com/watch?featur...V6zRvcLuY#t=77

[Russ]

Over-rated film starring Sandra Bullock and George Clooney.

[downquark1]

Classically speaking the energy is always there. It's called gravitational potential energy.

As you lift a ball onto a table you are giving it the potential energy to fall back down. When it falls it will exhibit no more energy than what it took to lift it.

There was the view that all the potential energy in the universe would eventually cause it to end in a big crunch. But I don't think this is the favored model these days.

Originally Posted by downquark1

Classically speaking the energy is always there. It's called gravitation potential energy.

As you lift a ball onto a table you are giving it the potential energy to fall back down. When it falls it will exhibit no more energy than what it took to lift it.

There was the view that all the potential energy in the universe would eventually cause it to end in a big crunch. But I don't think this is the favored model these days.

The ball is no example, the energy is supplied by you, an energy source.

Gravitational potential energy is energy an object possesses because of its position in a gravitational field. Huh ! Catch 22 ! We are back to gravity and where does it come from. What is it ? The base question of this thread.

Inert masses are incapable of exerting or generating energy. Back to the drawing board.

[downquark1]

Originally Posted by Wittmann

The ball is no example, the energy is supplied by you, an energy source.

Gravitational potential energy is energy an object possesses because of its position in a gravitational field. Huh ! Catch 22 ! We are back to gravity and where does it come from. What is it ? The base question of this thread.

Inert masses are incapable of exerting or generating energy. Back to the drawing board.

Yes, they obtained the potential energy when they exploded away from each other from the big bang. The field is always there and the energy came from the same place all energy comes from (whereever that is, don't ask me it's a mystery). Classically energy isn't a "thing" it's "the capacity to do work", the inert object has the potential (given how gravity works) to crash into another therefore it has potential energy.

If what you are looking for is a complete ontological description of gravity and/or energy I'm afraid that will never be coming.

[qasdfdsaq]

Originally Posted by Wittmann

The ball is no example, the energy is supplied by you, an energy source.

Gravitational potential energy is energy an object possesses because of its position in a gravitational field. Huh ! Catch 22 ! We are back to gravity and where does it come from. What is it ? The base question of this thread.

Just because you weren't around to see it doesn't mean it wasn't put there by God.

Inert masses are incapable of exerting or generating energy. Back to the drawing board.

Our Almighty Lord gives them energy.

---------- Post added at 18:21 ---------- Previous post was at 18:18 ----------

Originally Posted by downquark1

There was the view that all the potential energy in the universe would eventually cause it to end in a big crunch. But I don't think this is the favored model these days.

In isolation, it would. Then they discovered the cosmological constant. And dark energy. And now realize gravity is not the predominant force acting on space-time over large astronomical scales.

[Ramrod]

Originally Posted by Wittmann

The graviton is a hypothetical elementary particle that Quantum Physics cannot prove even exists - it is a pure theory.

That's what I said

Originally Posted by downquark1

If what you are looking for is a complete ontological description of gravity and/or energy I'm afraid that will never be coming.

I know, if scientists cannot find an answer, then a chat Forum can`t. I posted it for general interest and to make people aware that gravity is not just a figure of speech, it is a scientific mystery.

[progers]

It's what makes apples fall down from trees

[Osem]

... and leads to the formulation of universal laws by victims thereof...