why can't sound waves travel in space?

Because there is a near-vaccum in space, and sound needs particles and molecules in order to travel. That's the medium in which sound travels.

there is no medium for them to travel through.

sound needs air to vibrate through... no air in space

because space is like a vacuum that sucks everything away. Sound won't travel in a vacuum either.

Sound is caused by particles of air that are caused to vibrate. There are no particles of air in space, so therefore there is nothing to vibrate and pass on the "sound".
This is a very basic explanation, but it sums it up.

because sound is really a pressure wave, you cant have sound where there is no pressure (a vacuum)

Because it is to loud out there.

they can, but they need a transfer medium.

No matter to vibrate means no sound.