Why does gravity pull us down and not up?

So how come you feel only the pull of gravity.

The reason gravity pulls you toward the ground is that all objects with mass, like our Earth, actually bend and curve the fabric of the universe, called spacetime.

Spacetime is exactly what it sounds like: the three dimensions of space – length, width and height – combined with the fourth dimension – time.

Using some very brilliant math, Einstein was the first person to realize that the laws of physics work in a universe where space and time are merged together.

What this means is that space and time are connected – if you move really fast through space, time slows down for you compared to someone who is moving slowly.

This is why astronauts – who are moving very fast in space – age a tiny bit more slowly than people on Earth.

Remember, gravity is the idea that objects in the universe are attracted to each other because spacetime is bent and curved.

This is very similar to how the gravity of a heavy object – like the Earth – pulls things like you and me toward it!

To make things even weirder, since space and time are connected, time is also stretched by heavy objects.

That is why really massive things in the universe – like the Sun or black holes – have stronger gravity than Earth?

So why does gravity pull you down and not push you away.

This would be a gravity hill, not a gravity well.

As far as scientists know, matter – or stuff – always makes gravity wells and not gravity hills.

Scientists can imagine things made of exotic matter or energy that would cause gravity to push you off into space, but so far, no one has found anything that could cause gravity to push you away from Earth!

Earth's atmosphere and magnetic field protect us from harmful space radiation, but passengers bound for Mars will lose that protection.