How Hot Would a Light Saber Really Be?

Datagod asks: "Has anyone ever calculated the temperature you would need to be able to slice through steel like it was thin air? How hot would a light saber really need to be? Also, I am assuming that at least some of the metal would be vaporized and the expanding gas would fling bits of molten metal at the saber wielder. Wouldn't your average Jedi be horribly scarred from all this."

Re:Very hot.

[dnoyeb]

Somewhat hot.

Nanotechnology

[Travoltus]

A nanotech style light saber would be the best way to go. Nanites could burn through their target and work on a whitelist principle: a friend's DNA would be ignored.

Quite literally you could ram your nanotech light saber through a hostage taker and the nanites would decline to harm the whitelisted hostage.

I can't believe no one else thought of this. PATENT!!!!!! OMFG I am teh pwnz0r take that George Lucas!!!!!!

Mod me please?

[4D6963]

OK, since today the weirdest stuff happens out here, can I get this comment modded up? Looks like there just has to ask. Thanks alot.

Afraid

[Soulfader]

I don't know what the most frightening aspect of this topic is.

• The extraordinarily detailed answers from people who spend a lot of time thinking about this sort of thing.
• The retarded answers from people who don't spend a lot of time thinking about this sort of thing.
• The retarded jokes forthcoming about people's pulsing hot lightsabers
• The prospect of spending all day sifting through stuff like this looking for real news
• The fact that I'm rather curious about this myself.

I know very little of physics, Star Wars or other. So I shall link to the disturbing Star Wars-related musings [sigspace.net] of my friend instead.

Probably about as hot as an Ewok is deadly.

[GnoWay]

I always though it was funny that people did not buy into the success of the Ewoks in the last skirmish. They'll buy into death stars, light sabers, but then balk at the Ewoks.

Pretty Damn Hot.

[UnixRevolution]

A Lightsaber cuts pretty fast through materials like that. As for the metal bits we'll asume it propels them away from the user, somehow. As for the heat...a portable (55 amp) plasma cutter can cut 1/4" material at roughly 70 inches per minute. The plasma coming out is roughly 24,000 degrees, and is a stream traveling at 20,000 fpm. An industrial cutter can do roughly 1000 inches per minute. I wouldn't imagine its flame is any hotter than 30K degrees. a lightsaber, it seems, cuts WAY faster than that. I wouldn' t know how to estimate its temperature using the given info, but maybe someone else can.

Re:Very hot.

[RazorX90]

A friend of mine is plagued by the following question:

What happens when light sabers try to cut adamantium?

I'll spare the details / speculation and leave it open ended...

...This of course makes me wonder what a fight between Wolverine and a Jedi would be like.

Re:Your question ties into another question

[Anonymous Coward]

Emacs can create a core dump that it cannot edit.

Heard that somewhere in response to a statement like this. I thought it deserved repeating :)

Re:Probably about as hot as an Ewok is deadly.

[LouisZepher]

I could be wrong here, but I immediately see a statement being made that says "technology bad, nature good" that one would often find in some fantasy-based video games. (Many say that Final Fantasy 6 is a prime example of this.) I can't say for certain whether Lucas meant this, however...

Re:Probably about as hot as an Ewok is deadly.

[Dmala]

I think most people would have been fine with ewoks if they'd at least been carrying stolen imperial guns or something. It still would have been silly, but suspending disbelief would have been simpler.

Funny, I seem to recall hearing that in an early draft, the Ewoks were supposed to be a space-faring, semi-technologically advanced race. I think it might have even been that they were supposed to be Wookies. Then when the toy sales blew up after the first movie, Lucas re-wrote them into an excuse to sell plush dolls.

Consider oxy cutters and plasma cutters instead

[dbIII]

These things don't exists

True, and the headline shows an ignorance of basic chemistry. Any oxy-acetylene cutter doesn't have to be hot enough to melt steel - the steel oxidises and burns away - so some sort of device that ionises air would be hitting steel with a lot of hot oxygen and burning it away. An oxy torch that cuts through steel like butter has trouble getting through aluminium alloy despite it having a melting point around 1000k less.

Plasma cutters are something else again, real and possibly far more like a light saber would be if such a thing was real. Heating up a gas and making it behave a lot like a liquid to burn things away leaving nothing but a clean cut and hot dust is the way the things work - all you need is high voltage electricity, appropriate electodes and a good supply of pressurised gas.

Slashdot killed my inner nerd

[SigmaEcho]

Normally, my interest in applying practicle science to the star wars universe would be astronomical, but reading the question in pink GUI made me realize what a nerd loser I was. Thanks a lot slashdot. :-(

Re:The real question is really...

[bogjobber]

Also going off-topic, God can't renounce his omnipotence. It is part of his nature. That is, even for God there are limits and omnipotence is one of those things that just "is". So in a way, he's not completely omnipotent. Right now it's really late and it's been a while since freshman philosophy class so that's the best I can come up with.

Re:I was actually asking a serious question...

[Terminal Saint]

Well for a serious answer, take a look at model number six over yonder http://www.geocities.com/deathcommando.geo/ls.htm [geocities.com] it's my favorite possible lightsabre operational model. To sum up, according to this model, a lightsabre is a rapidly spinning charged superconducting field. Given this model, the cutting is caused not by heat, but by the shearing off of the electrons that bind atoms together, thus, heat is not a problem for the operator.

Re:Very hot.

[BakaHoushi]

I don't know about adamatium, but I do know in the SW Universe there exist metals that can withstand a Jedi's lightsaber. Cortosis, I believe it's called. Most metallic weapons in Knights of the Old Republic used them so you couldn't just mow down enemies, and Jedi Knight II had villains who made armor out of it. I don't know how, exactly, it resists a lightsaber, but it seems pretty good at it.

Re:How hot? enough to burn the user?

[matt21811]

I used to work for BHP (now Billiton) at the Slab and Plate product division. I worked in PC support and so didnt actually know much about the steel making. One day I had to visit the BOS (I stil dont know what it stands for), it was the area where they stored the slabs after they were poored. I got out of my car and was hit by a stifulling heat but I couldnt tell where it was comming from. I looked around and 40 meters away was a large slab, cooling in a neaby fenced yard. It was barely glowing red.

If a light sabre is say, twice as hot as that then I dont care how small the sureface area is you are going to notice it if its less than 1 meter from you.

Re:The real question is really...

[rgoldste]

Scott Adams wrote a book, God's Debris [andrewsmcmeel.com], that explores your question of what happens if God gives up his omnipotence. I'll let you read the free ebook yourself, but the basic idea is that God, as a perfect being, gets bored of his own existance and tries to spice things up by committing suicide. In doing so, God created the universe.

Wikipedia notes the parallels of this to Hinduism. When I read God's Debris, I was reminded of GWF Hegel's Philosophy of Religion, where God also empties himself of divinity in order to start time and create the universe because he realized that his pure existence is meaningless. Time is the progress of God, the spirit of whom is now extended in all matter, coming to 'realize' himself as God. So, in a sense, God is evolving.

These theological moves (God is extended in the world and God is realized in the future) allow for dodging some thorny questions. For example, Can God create a rock that he can't lift? The answer is, for *now*, yes. But he might be stronger tomorrow.

Answer from a welder - steel melts at approx. 2500

[koelpien]

I work in a shipyard as a welder. I can tell you that steel "melts" at approx. 2500 F. However, other metals such as aluminum and copper are welded at much higher temperatures, Of course, something like ceramic is much more "unmeltable" than metal, and we wouldn't want to think that you could fend off a lightsaber attack with a ceramic coffee cup. It's not just a matter of heat. Of course, lightsabering could be said to be more closely related to plasma cutting than welding. In simplest terms, plasma cutting is a process that uses a high velocity jet of ionized gas that is delivered from a constricting orifice. The high velocity ionized gas, that is, the plasma, conducts electricity from the torch of the plasma cutter to the work piece. The plasma heats the workpiece, melting the material. The high velocity stream of ionized gas mechanically blows the molten metal away, severing the material. Then again, welding and plasma cutting only works with conductive materials, like metal. You can't plasma-cut an arm off. The another issue is that both welding and plasma cutting require your material to be grounded, plasma cutting requires a source of compressed air, and an incredible source of electricity/ amps in a power source the same size, or smaller, than several of our "D" sized batteries. We do know, however, from watching "Empire" that they have portable welders, which they use (uselessly) to defend Hoth.

Re:I was actually asking a serious question...

[maquah]

To melt it, somewhere in the ballpart of 1515 C if it's 'mild' steel, the temperature depends on the mixture (alloy) of iron, carbon, chromium, the blood of sacrificial mice ... whatever else.
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Can you melt steel with a laser? Yes ...
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but melting it or vaporizing it [lots hotter - above the boiling point of iron], would, as a number of other people have noted here, involve huge amounts of energy, raise the temperature of the surrounding area and perhaps cook the laser-wielder, etc.
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Probably the 'light' of a light-saber is something like ionic traces from the passage-through-air of some as-yet-unknown in the here-and-now power, as it vectors (y'know how things are in Hollywood) toward the steel ... and then the power released from dematerializing the steel flows BACK to the light-saber (it would need to be a self-recharging subatomic-powered weapon: running a gaget like that on a battery pack would be unwieldy)
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Some people have considered the 'telekinesis' question, including why a person would need a light saber at all, if a master of telekinesis.
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Using telekinesis as a weapon against living beings draws a the user into dreadful depths of the dark side ... it's not worth it.

Re:I don't think it's the heat that does the cutti

[Anonymous Coward]

Really, you guys need to spend more time on weldingweb.com. They all know that to cut steel you only need to heat it to about 2200F, then you simply spray it with oxygen and it oxidizes which releases more heat and.... continues the cutting process. You don't even need heat after the initial heating to its melting point, just a steady flow of O2.