Re: Question about gravity (curved space?)

So backwards and forwards on the x- y- or z-axis, but only forwards
on the t-axis?
BTW, what does "'moving' through" mean?
Trains go along the track, not through the track... perhaps that's
why you have so much trouble measuring their velocity.

Seems that way.

--
Martin Hogbin

So backwards and forwards on the x- y- or z-axis, but only forwards
on the t-axis?
BTW, what does "'moving' through" mean?
Trains go along the track, not through the track... perhaps that's
why you have so much trouble measuring their velocity.

The t-axis ?

--
Martin Hogbin

Is that along the x, y or z axis?

Forwards.

--
Martin Hogbin

Which direction?

In spacetime you are always 'moving' through time.  In flat (non-curved)
spacetime, as you 'move' through time you do not move through space.

Gravity curves spacetime in such a way that, as you 'move' through time
you move through space.

Would you like a two dimensional example?

Yes, insofar as a heavy object will accelerate the Earth towards it.
In other words, so the relative acieration of the two bodies is greater.
However, the acceleration of the falling body relative to an inertial
frame will be the same whatever its mass (in Newtonian physics).

--
Martin Hogbin

Thanks for all the answers, but I still don't quite get it. Maybe if I
ask it differently...

How does the curved spacetime cause an object to accelerate towards an
other object?

Also wondering, I always read that objects always fall as fast on
earth no matter what their mass is (in vacuum), but shouldn't heavier
objects fall faster?
Maybe not measurable because the difference in mass is rather small
compared to the mass of earth but still, if you'd put 2 earths next to
each other they'd go twice as fast towards each other right?

Hi,

I was wondering, if gravity curves space, then why does it matter how
fast you move through this space?

If it's only curved, the speed at which something moves through it
shouldn't make a difference on it's angle should it? If it would,
wouldn't that mean there's inertia which would be strange if space
itself was curved (ie something moving through it would have to think
it's going straight).

I'm probably just missing something but couldn't find an answer.