Wouldn't gravity have no effect on something with no mass?
Bag gloves are typically smaller than you'd want a sparring glove to be, they're of a different cut, the padding is much harder for repeated abuse against the bag, and repeated bag use leaves its mark on the outside of the glove which is what comes in contact with your sparring partner's face. You wouldn't want your sparring partner wearing them right? You don't need to go for Thai gloves, I actually recommend a pair of traditional sparring gloves.
Compact disks are made up of multiple layers of materials. They have a silver surface to reflect the laser light, so that it can be 'read'. That makes the surface reflective. On the silver surface, there is a thin layer of plastic on it. The thin layer leads to interference which gives the colours (of the rainbow, the components of white light). This is similar to the colours one sees when oil is spread on water, or for a soap bubble.
The information on a CD or DVD is impressed onto the plastic disk when it is molded. (small impressions in the plastic which correspond to the 1's and 0's which the laser will read as digital information) The plastic doesn't reflct much light until it is metalized - coated with a very thin layer of shiny silver or gold. This surface is very fragile and it is followed by a coating of laquer to protect it. This clear coating on the surface bends the light (first entering the disk and again when it exits) and the reflctive metal sends the defracted light back, much the same as when you create a rainbow by misting the water from a garden hose on a bright, sunny day.
