Gravity! What is it good for?!... Absolutely nothin'! -Say it again!
Gravity! -Oh wait... no. That's 'war' I was thinking of. Yeah. No, thinking about it, gravity's actually quite useful.
So I really didn't want to have to explain this any further, what with having explained gravity away on three different levels:
And thus far you can take all the above as absolutely true, and non of it contradicts it's self. No.... Not at all. Not really. Each one is a deeper understanding of the basic principle. (Although on the face of it, Part one kind of looks like a load of bollocks, but that's not to say it definitely isn't true, and you can't prove otherwise!)
Well this section (that i imaginatively call 'Part Four' )will give the most basic underlying reason why the gravity effect happens. It is the most basic, and beautifully simplistic cause of the 'force' that we call gravity. And it only occurred to me last week:
Gravity is an effect that happens to objects because all objects in space are falling.
This may seem like a circular argument for you may think that you cannot use the effect of gravity to explain the effect of gravity. But when I say 'falling' I mean travelling in space in whatever way/direction it happens to be travelling. All objects do this. It's the law of inertia; An object will never change it's speed or direction unless it is acted upon by another object/force. So all objects are constantly falling through space... constantly.
You still with me?
Ok, so the reason these objects' trajectories are affected by other objects is all about the law of inertia. Without anything affecting it, a planet will always stay constant. ie. it will not change direction, and (if it is moving) it will not accelerate or decelerate.
Although to say it won't accelerate or decelerate is wrong... as there is no such thing as absolute space or indeed absolute speed: If one planet goes past another there is no way to say which planet is moving or which planet is static. You can't say at what speed anything is ultimately travelling at.
At this moment, you may be sat still. ...but are you really? What if you where sat on a train, you maybe travelling at 100mph. ...and the old lady walking up the train towards the buffet carriage might be moving faster (at 102mph?).
Even if you're not on a train, the earth is spinning which means you could be moving at about 1000mph. But this is just the speed you move on a daily basis, the earth spins (relative to the sun). What about the earth's orbit of the sun? You're actual travelling at a rough average of 66500mph. Except that's still only relative. You're often actually going faster than that, as the sun is travelling at immense speed around our galaxy. But then that is still only relative to the centre of our galaxy and the positions of the other galaxies. What about the speed at which all galaxies are travelling away from one another? That speed in itself is relative as we have no other point of reference. It is an assumption that galaxies are move at the same speed and this way we can backtrack and figure out the point in the universe where it all began. ...relative to our universe. I believe we're part of an omni-verse full of universes so far away that they're not nearly old enough for the light from their origin to even reach the outer edges of our universe. These other universes will no doubt be travelling at their own speed relative to our own in whatever direction, and again there's no way to determine how fast (if at all) each universe is travelling...
But I digress...
The idea behind my statement 'all objects in space are falling' is that the object don't deviate from their course. In fact relatively speaking, they don't necessarily have a course... or a speed. If you want to believe that you are the centre of the universe (as I do), then that's fine as there is no such thing as absolute space. Only relative space and relative motion exists. This ties in to the law of inertia. Objects keep their same relative position in space, and they keep their same relative speed that they're relatively moving at. ... relatively.
It's like water will always flow in the path of least resistance. Or to use an analogy that is unrelated to gravity: Light will travel in the path of least resistance, ie. the shortest route to it's destination. It's true that light goes in every direction, but if you were to obscure star a from direct view with a planet in the way, the light from the star can still bend around the planet to reach you. But obviously this only works to a certain point. If photons from a source can reach a destination, then they will have got there via the easiest route possible.
So... we're on a planet falling through the universe at an incredible relative speed to the rest of the universe. Luckily this speed is relatively diminished greatly by 1) being drawn to the large mass that is our sun, and thus making us seem relatively slower on a local level... and 2) our solar system is made relatively slower by moving approximately the same speed as lots of other solar systems that surround us in this spiralling whirlpool-like collection of solar-systems that we call the Milky Way.
This is what Gravity is. In actual fact, the universe isn't going at any great speed. There is just the relative differences from one thing to another. Mass affects and attracts other masses to a certain extent. But more so for masses that are travelling at a similar speed and/or in closer proximity. We don't float away when stood on the earth because of the size and proximity of the planet. It is our 'path of least resistance'. Even if we could float up in the air (and imagine if we were the size of an oxygen molecule for this) we wouldn't get beyond the stratosphere because we have a mass and still need to 'fall' in the path of least resistance. Such a path does not include leaving our atmosphere to go out into space that is relatively moving (it's not actually moving) a hell of a lot faster than we are. It'd be like joining a busy motorway via a T junction when everyone's going at 70mph in the slow lane, and you're driving a milk-float.
In short, a planet revolves around a sun because it does: It's either always been there, or has entered the sun's vicinity, and didn't have enough energy to continue it's original trajectory back into relatively-different-speed space. It would have altered it's course accordingly. Like if there was a fly in your car, and you're driving at 70mph. The fly isn't flying at 70mph. Then you open the window and if the fly leaves it doesn't continue at the same speed as the car. (though it probably goes a bit faster than it would normally fly in that direction for a short time).
To sum up...
You can call gravity a force if you want... but what is any force but an affect of some other phenomena? In this case it is caused by the relative difference between the speed you're travelling at, and the relative speed of your nearest local moon/planet/solar-system/galaxy/universe.*
*delete as appropriate.
