[quote=@Host]
<Snipped quote by souleaterfan320>

Shadows result when light is absent from an area where much light is. Plus, matter is anything that takes up space.
[/quote]
https://van.physics.illinois.edu/qa/listing.php?id=2004

There you go.

And technically, the shadows he uses are spiritual, therefore have some sort of stability, allowing them to stand on it.