Re: If light isn't matter how does a black hole 'suck' it in??

To answer this it is necessary to develop the notion of 'space-time'. The simplest way (although slightly inaccurate way) to conceive this is to imagine space as a rubber sheet! Any massive objects (planets, stars, large ball-bearings, etc.) will distort this sheet. See here for more details.

If you then imagine a small ball-bearing rolling on the sheet, its path will be altered as it passes the more massive bearing. This IS gravity.

It can be summed up by the quote: "Matter tells space how to bend, space tells matter how to move"

Now, one of the consequences of this is that even light (which travels at a finite speed) is affected by gravity. This effect has been observed during solar eclipses.

To now consider black holes, imagine a star getting more and more massive. The path of any light passing it will then be more and more distorted (bent towards the black hole) until it actually can't pass! See here for more details.

This is the definition of a black hole. It is a body so massive that even light can't get past it. Incidentally, there are actually two parts to a black hole. There is a 'singularity' at the centre (this is a point of infinite density) but around this is the event horizon. This is the radius from which nothing can escape. For example, if the Sun turned into a black hole this instant, the Earth would still go round it and would not be 'sucked in'.