KSarty said:
Yes, basically. We're talking about a metal that the Hulk can't even scuff.
Well, if we're going to be completely hypothetical here I'd say that I find the notion of a superconductive material to be A LOT more believable than a "lightsaber".
I've always hated lightsabres for the sole reason that there is no respect what so ever to how actual light behaves. Light doesn't conveniently "stop" at a certain length in such a manner that it can form a manageable "blade" to be used as a sword. Photons keep going the direction they are going until they collide with something that absorbs them, and the last time I checked air is pretty bad at absorbing photons (especially the amount that a supposed "lightsabre" would generate if it wishes to maintain that awesome cutting power).
And don't even get me started on how the hell they actually power those things. I mean sure, there are nanotechnological solutions to many things but maintaining a high-powered laserbeam like that with an object no bigger than your average flashlight? BAH!
So for sheer plausibility, I'd say that the adamantium wins. After all, superconductive materials actually exist (even if they have to be cooled down to extreme temperatures to actually become superconductive), and from a scientific standpoint I'd say that superconductivity in room temperature might be within the realm of possibility through nanotechnological solutions.
Also, light isn't some kind of superpower that can defeat anything like some lightsabre-fans seem to think. For instance, what do you think would happen if a lit lightsabre ended up too close to the gravitywell of a black hole? (you know, that cosmic phenomena that even sucks up LIGHT along with everything else?)