Gravity is... what?

 

What goes up must come down, right?

That's gravity.

 

So how does that apply to Ol' Mother Earth,

or anything else for that matter?

I mean, if you were standing at the North Pole

there would be no question as to

what was up and what was down.

Take a look at the globe.  It's obvious.

But, let''s say you were standing somewhere

in central Africa.

Maybe not so obvious then?

From your perspective, yes it would be,

but from looking at the picture of the globe

you'd be standing... sideways.

Does that mean there really is no up or down?

Sort of.

Up would be in any direction going away from the earth,

and down would be toward the center of the earth.

Always.

No matter where you are on the planet,

no up, no down.

Just away from, or toward.

Anyhow... back to "What is gravity", really?

What makes it tick?

How does it work?

Gravity is a force of attraction 

between any two things that

pulls them toward each other.

Why?

Because any object that contains mass or energy

creates a gravitational pull.

Issac Newton figured it out when that

apple fell from the tree and landed on his head.

There was an attraction between

the apple and the earth.

Both were objects, and both contained mass,

so there it was.

Pretty simple, for him at least.

I needed something more simple than that though.

Newton eventually explained it thusly.

The law of universal gravitation states that the force 

F is F=G m1m2/r2, where G is the gravitational

constant, m1 and m2 are the masses of the objects,

and r is the distance between them.

Better, right?

No freaking way...

Einstein!

Einstein had the answer.

His theory of Relativity showed that gravity

was the curvature of spacetime caused by

mass and energy, not just some

traditional force, and we, the little people,

perceive that as a gravitational pull.

See?

Nope, me neither, and guess what,

neither did they.

Everything that Newton and Einstein

came up with are actually theories.

Good ones, but theories none the less,

and there are no actual facts to back

either one up.

Truth is, nobody really knows what gravity is,

or exactly how it works.

Someday maybe someone will,

but not today.