The Kestrel Minority

As I understand it, lightsabers give off no heat at all. They do "burn" through things when they cut, but they also cauterize or seal the cuts, so for example lightsaber wounds don't ever bleed.

Now in terms of clothing being set on fire by lightsabers, we have a few examples of what would happen.

Obi wan's clothes in Ep4 didn't set on fire.

Qui Gon's clothes and Darth Mauls didn't set on fire.

Clothes get burn marks when a lightsaber cuts into them, but don't burst into flames. This is because the source of the heat is the saber blade, which only touches the contact area for a split second.

It might be if a lightsaber was pushed into a massive pile of dry clothing and held there, they would burn but not from a cut or stab.

This is why the blast door in Ep1 started to melt, because the heat from the blade was held in place for a long time.

Why can't it just be up to the wielder - it is their force control that holds the blade tight - but i assume if you were good you could control the output. You would normally keep it tight and hence more effective to slash/stab rather than wasting the energy.

Just a thought to possibly explain.

If someone gets impaled by a Lightsaber , then slumps to the floor but the wielder keeps his LS where it is, will the victim vertically slice themselves in half ?

Plus Obi-Wan and Qui'Gon don't die in the traditional sense. Don't they become immortal within the netherworld of the force....? Or something along those lines.

I think because light sabers are wielded like swords, (hilts etc) people consider them to be "laser blades". But I just think they are something else, other than an extremely hot "laser". Even though they do cauterize wounds and can melt solid metal.

I'm confused

My understanding (and I am by no means an expert) is that a lightsaber is a beam of plasma circulating inside a containment field, so you have a kind of current flowing, with plasma flowing out in the center of the beam, till it hits the end of the containment field then flowing back towards the hilt along the outer part of the blade and the process repeats. While the plasma is extremely hot it's heat is completely contained by the saber, if the containment field ever broke the circuit would short and the lightsaber would sputter out.

The 'heat' from the blade is actually created by the intense electromagnetic field generated by the circulating plasma. The burns caused by the saber are more like electrical burns, the kind you'd get from touching power lines. I'm sure you've all seen those old electric heaters, with the iron bars wrapped in wire, when they switch on the current passing through heats up the bar. It's a similar effect when the lightsaber hits an object, the intense electromagnetic field induces a current which in turn generates heat. The same electromagnetic field is the reason sabers repel one another and why the charged energy from a blaster is deflected.

Sadly I don't remember where I picked up the concept that the cycling plasma generates an electromagnetic field, so I can't honestly say if it is cannon or not. But it does make sense and explains most of the sabers properties.

As for the actual thread question, it's like Doon said, the heat is only generated while the saber is in contact with something dense enough to offer resistance to a current. The reason only the immediate area is burned is that the heat doesn't transfer fast enough, the part in contact with the saber burns, but then it's gone, so no resistance and the current no longer generates heat. Maybe think of it as cutting steel with a blow torch, the whole sheet of metal doesn't heat up at the same rate, just the area under the flame?
I suppose if you stuck the saber against something highly flammable, like starship fuel or something, it'd burst into flame easily enough?

Finally I'm reminded of a line I heard once.
"When it comes to sci-fi technology, never poke the plot holes; you never know when one'll collapse into a blackhole and take the whole franchise with them"
I think it was originally in relation to something about star trek, but it seems to apply here. Sometimes you have to overlook impracticalities in sci-fi tech and just go with it and the cannon seems to be that clothe,. etc. don't burst into flame... Unless it's doused in oil, or would make a for an impressive scene

If lightsaber cuts, it can shortcut what it cuts, fire. Now can a lightsaber cut fire?

The little wooden tapers I use for my Wood Burning Stove can certainly 'cut' fire. It just comes back again, damn those ethereal flames!

Ex

I actually went and nerdered out on wookiepedia.
So heres the lightsaber info on there.

http://starwars.wikia.com/wiki/Lightsaber

And a section which relates to this thread.

"A lightsaber blade was a mass-less form that neither radiated heat nor expended energy until it came into contact with something solid. The power of the energy blade was so great that it could cut through almost anything, although the speed through which it cut depended on the density of the subject. One important note about lightsaber wounds is that they rarely bled profusely, even when a limb had been severed. This is because the energy blade cauterized the wound as it passed, and thus even a severe wound did not tend to bleed heavily.

When cutting through dense material, the immense electromagnetic field generated by the arc caused resistance rather than letting solid matter enter and interrupt the arc. This gave the blade a feeling of being solid when immersed in dense material. Rarely, some solid materials could actually pass through the electromagnetic field and short out the arc. Other electromagnetic energy fields and coherent energy were also repelled by lightsabers' arcs. These include most force fields, blaster bolts, and other lightsaber blades. "

The biggest mystery in star wars universe, why smugglers have no light knifes. It would be very effective to open doors.