Back on Ultracold plasma, the only things I can substantiate against it's possibility (had to fact check, been a while since I've taken physics), if a lightsaber were ultracold, it would affect air around it in a noticeable way, by cooling the air around it, that air would mix with the warm, making it seem as though it were emitting a fog, with modern tech it needs to be contained, and if the blade where cold it would not make other objects emit light as it does when it cut's through things. Theoretically it could cut through things by ultracooling the atoms, which has proven to speed up some atoms faster than at room temperature (heat causes atoms to speed up, cold slows them down, typically) causing displacement, and there where cold sabers in the EU, but the mechanics were brushed over for the occurrence I'm thinking of was in a video game. A heated plasma with a significant amount of charge carriers, using an electromagnetic field to keep the blade shape (Plasma is a state of matter like gas as in it has no shape, but is strongly influenced by electromagnetic fields when it has many atoms carrying a charge) would be most logical in comparison to real world tech, as the cold plasma was suggested by that comparison. Still it I feel the blade is too well contained with all the electromagnetic fields being generated in the Star Wars Universe. Other arguments against cauterization, were Luke having the circulation cut off after his hand was cut off, which does not take place, unless referring to the device placed over his nub, but like I said, you still bandage burns. If you watch episode 5 it doesn't bleed, if lightsbers caused any bleeding Luke would have died of blood loss before he was found (was cut from the wrist 10-15 mins to bleed out), his shirt he hid his nub in would have been bloodstained, and you actually get a pretty good look at his nub while he's hanging under cloud city (which he would have passed out by then from bloodloss), where it has no blood, but also has no prosthetic on, so it looks like a healed nub. Further proof is when Leia is shot in ep. 6, her poncho starts on fire, yet to further the blood argument Han's hands are bloody from Leia's wound. I think looking at all the evidence, it's left for the director to choose to help base the tone for the scene, like how JDeck said the prequels would have been a bloodbath if everyone bled, and how the dead solders are never bloody for they want you too feel the tide of the battle, and not the tragedy of death, or massacre as the camera brushes past them. Though as an avid Star Wars fan that's read the books, including the informational ones like the Essential Guide to Alien Species cover to cover, it leaves a bitter taste being undefined, no matter how logical from a director standpoint.
