So to start, we know the void surrounds all things and is energy. We also know that in the Golden Age humanity had antimatter technology, and since Bungie has so far stuck to their energy usages (solar energy farms on Mercury and arc energy generators elsewhere) we can assume that void is antimatter since antimatter surrounds all matter and has energy. We can convert our Light into void energy and weaponize it just like with the other two forms of energy. (Here's the theory work) Back to the void itself, it seems to be a very basic and powerful form of energy as it seems most utilized by the Traveler and Darkness. The Traveler came to our reality through the void and built its body with it. It did this because the void is supposedly what makes up what we know as the Veil, which is the boundary between our reality and others. Since the void surrounds all things in our universe it can be said that it also surrounds other realities, therefore making the void and Veil the same. We can also use Mara Sov's ability to both use void energy and her ability to peer through the Veil as a hint that these are the same, as well as the fact that Oryx and the Worms can speak to the Darkness by thinning the Veil (Oryx and the Worms are known to have great control over the Void due to their power and we know that the Darkness is on the other side of the [b]void[/b] as the Traveler once was) It should also be noted that being able to peer through the Veil can let you see through time and receive visions, most likely because the Veil surrounds [i]all[/i] of our time and space or because the other side isn't bound to our concepts of time