Quote Originally Posted by Mechalich View Post
A lightsaber is a continual plasma stream, with particles held in place through the use of an extremely powerful energy field. 'Solid' isn't really a term that applies. For comparison, a high-powered water jet isn't solid, but it still possesses force an the ballistics of a bullet impacting such a stream are quite different from an equivalent still mass of liquid.
This would be fine if we didn't see things like Ahsoka's lightsaber acting solid in The Mandalorian, or people lodging them into rocks to catch themselves while falling in at least one of the new comics.

The density of lightsaber blades seems to be somewhat variable depending on situation.