Why don't lightsabres make people explode?

[Crazedwraith]

Which is?

Maybe the one Spanky's been talking about for the entire thread?
Electron shearing?

But his interpretation of that is that the blade does it without directly heating the material. And that all of the heat comes from the atomic vibration caused by the shearing. Which it can't:

*ahem* you cannot strip electrons from an atom without supplying the necessary energy to make up the difference in electrical potential energy states. That pesky First Law of Thermodynamics again.

*shrugs* He said "widely acccepted" theory not "correct and possible" theory.

[Metrion Cascade]

Maybe the one Spanky's been talking about for the entire thread?
Electron shearing?

But his interpretation of that is that the blade does it without directly heating the material. And that all of the heat comes from the atomic vibration caused by the shearing. Which it can't:

*ahem* you cannot strip electrons from an atom without supplying the necessary energy to make up the difference in electrical potential energy states. That pesky First Law of Thermodynamics again.

*shrugs* He said "widely acccepted" theory not "correct and possible" theory.

If someone says there's already a widely accepted theory and leaves it at that, I take it to mean they agree with that theory (and are using an appeal to popularity) until they say, "but I don't agree with it."

[PainRack]

But his interpretation of that is that the blade does it without directly heating the material. And that all of the heat comes from the atomic vibration caused by the shearing. Which it can't:

No, that would be an misinterpretation of the theory. Supplying 100 MW power into metal is not equals to supplying 100 MW power into the air.

The question would be the selectivity, why the lightsabre dumps so much more energy into metal, or higher density material than into air. Its supported by canon, where the lightsabre hilt is not hot to the touch but apparently has enough energy to cause the door to melt down.

There's also a question of to what extent the lightsabre heats its surrondings. Canon suggest that it doesn't do so( TESB ice scene as well as ANH novelisation), but the EU, specifically, Corran attempts to free slaves on Belkadan suggest otherwise.

[Darth Wong]

The question would be the selectivity, why the lightsabre dumps so much more energy into metal, or higher density material than into air. Its supported by canon, where the lightsabre hilt is not hot to the touch but apparently has enough energy to cause the door to melt down.

One hardly needs to invent fanciful explanations for that. A modern laser dumps its energy into metal very effectively, but has little noticeable interaction with air. Air is, after all, an insulator.

[Howedar]

Of course, pump enough energy into the air and you start to get thermal blooming problems (at considerably less than a lightsaber's 100MW, IIRC). Not a perfect analogy.

[PainRack]

One hardly needs to invent fanciful explanations for that. A modern laser dumps its energy into metal very effectively, but has little noticeable interaction with air. Air is, after all, an insulator.

However, we do know that lightsabres do interact with air, hence, the humming sound.

[Metrion Cascade]

One hardly needs to invent fanciful explanations for that. A modern laser dumps its energy into metal very effectively, but has little noticeable interaction with air. Air is, after all, an insulator.

However, we do know that lightsabres do interact with air, hence, the humming sound.

That could be the forcefield. We know they aren't dumping the same energy into the air that they did into that Trade Fed door.

[Sarevok]

One hardly needs to invent fanciful explanations for that. A modern laser dumps its energy into metal very effectively, but has little noticeable interaction with air. Air is, after all, an insulator.

However, we do know that lightsabres do interact with air, hence, the humming sound.

That could be the forcefield. We know they aren't dumping the same energy into the air that they did into that Trade Fed door.

Wong had a good point. A modern laser dumps far less energy into air than metal. The same thing may be also true for lightsabers.

[Metrion Cascade]

However, we do know that lightsabres do interact with air, hence, the humming sound.

That could be the forcefield. We know they aren't dumping the same energy into the air that they did into that Trade Fed door.

Wong had a good point. A modern laser dumps far less energy into air than metal. The same thing may be also true for lightsabers.

Not less energy. Same amount of energy, lousier thermal conductivity. And with the amount of energy a lightsabre releases, air's lousy thermal conductivity may not make a whole lot of difference. Standing 20 ft from a blast furnace once came close to burning my skin. And that's just modern metals - steel and such. The Trade Fed door must have required far greater temperatures if the Feds have better alloys than we do, and Jedi walk around with these things on inches from their bodies with quite some frequency. They don't get burned, people and objects near them don't get burned.

EDIT - actually thermal conductivity shouldn't matter much at all. Lightsabres release their energy in radiant form, not like a hot object in contact with air. Air's effect wouldn't be one of conducting the energy - it would slow it down (negligibly). I think DW's laser analogy is off. Air barely interacts with lasers not because it's an insulator, but because unlike metal it's transparent.

[Stark]

Could the motion of the 'blade' be important to how it behaves? In TPM the blade is being yanked around pretty hard inside a (probably) dense material, whereas in combat it's used differently. There's the ROTJ skiff fight and the ESB incident with Vader's armour; perhaps whatever mechanism the blade uses is affected by the mechanics of its motion? Don't ask me, I'm not sure if it's 'affected' or 'effected'

[PainRack]

Not less energy. Same amount of energy, lousier thermal conductivity. And with the amount of energy a lightsabre releases, air's lousy thermal conductivity may not make a whole lot of difference. Standing 20 ft from a blast furnace once came close to burning my skin. And that's just modern metals - steel and such. The Trade Fed door must have required far greater temperatures if the Feds have better alloys than we do, and Jedi walk around with these things on inches from their bodies with quite some frequency. They don't get burned, people and objects near them don't get burned.

EDIT - actually thermal conductivity shouldn't matter much at all. Lightsabres release their energy in radiant form, not like a hot object in contact with air. Air's effect wouldn't be one of conducting the energy - it would slow it down (negligibly). I think DW's laser analogy is off. Air barely interacts with lasers not because it's an insulator, but because unlike metal it's transparent.

Look, for the last time, 100MW of power into metal is not = 100MW of power into air.

The Lightsabre did not dump the equivalent amount of energy into air as opposed to into metal, period. This is more than amply proven in canon where the lightsabre hilts are not hot and it did not melt the snow in Hoth. Stop thinking of the lightsabre in terms of it being a blowtorch. Its not.
The best theory for it is either the plasma forcefield, electron stripping blade. Someone once posted a theory about quantum seperation of states, stating if some "unknown" ability exists to seperate the quantum states, it might be possible to explain some of the cutting effects of the lightsabre.

But no matter what, its not a blowtorch, and it doesn't work by sending a huge energy blade into the air which by the laws of thermodynamics, will radiate heat away. Its more like an electric circuit, where the amount of electricial energy in the circuit is dependent on the potential difference.

Last but not least, air barely interacts with lasers because of the molecules. Not because it has low thermal conducivity or low transparency. MW notes about the insulator was in response to the lightsabre heating properties on its environs.

[Metrion Cascade]

Not less energy. Same amount of energy, lousier thermal conductivity. And with the amount of energy a lightsabre releases, air's lousy thermal conductivity may not make a whole lot of difference. Standing 20 ft from a blast furnace once came close to burning my skin. And that's just modern metals - steel and such. The Trade Fed door must have required far greater temperatures if the Feds have better alloys than we do, and Jedi walk around with these things on inches from their bodies with quite some frequency. They don't get burned, people and objects near them don't get burned.

EDIT - actually thermal conductivity shouldn't matter much at all. Lightsabres release their energy in radiant form, not like a hot object in contact with air. Air's effect wouldn't be one of conducting the energy - it would slow it down (negligibly). I think DW's laser analogy is off. Air barely interacts with lasers not because it's an insulator, but because unlike metal it's transparent.

Look, for the last time, 100MW of power into metal is not = 100MW of power into air.

What's the difference? Equal amounts. Dissipated differently, but there should still be some heating of surrounding objects if 100 MW of radiant energy are being released omnidirectionally.

The Lightsabre did not dump the equivalent amount of energy into air as opposed to into metal, period. This is more than amply proven in canon where the lightsabre hilts are not hot and it did not melt the snow in Hoth. Stop thinking of the lightsabre in terms of it being a blowtorch. Its not.
The best theory for it is either the plasma forcefield, electron stripping blade. Someone once posted a theory about quantum seperation of states, stating if some "unknown" ability exists to seperate the quantum states, it might be possible to explain some of the cutting effects of the lightsabre.

But no matter what, its not a blowtorch, and it doesn't work by sending a huge energy blade into the air which by the laws of thermodynamics, will radiate heat away.

I'm not saying it releases energy (other than visible light) into the air. I'm saying it's separated from the air by a forcefield that's too weak (by design) to prevent interaction with solids. It touches solids, the forcefield is breached where it touches, and energy leaves the blade and starts going into the solid.

Its more like an electric circuit, where the amount of electricial energy in the circuit is dependent on the potential difference.

That's a useful analogy if you're talking about heat moving from one object to another. Not radiant energy. Heat moves from a hotter object to a cooler one. Radiant energy moves until hindered by something non-transparent to it.

Last but not least, air barely interacts with lasers because of the molecules. Not because it has low thermal conducivity or low transparency.

What about 'the molecules' prevents lasers from interacting with air? Not that it matters - transparency is (by definition) what allows visible light to move through matter. Nor did I say that air's thermal conductivity lets lasers move through it (especially considering air has lousy thermal conductivity compared to most solids but interferes with lasers far less). A vacuum, for example, has no thermal conductivity whatsoever but is the perfect environment for light to travel through unhindered.

EDIT - fixed quote tag and changed "matter" to "solid/solids." Also elaborated on why the potential difference analogy doesn't apply to lightsabres.

[PainRack]

What's the difference? Equal amounts. Dissipated differently, but there should still be some heating of surrounding objects if 100 MW of radiant energy are being released omnidirectionally.

Let me try saying this in another way.

The lightsabre, does not automatically has 100MW of power in that blade. And no, its not a low power settings type of question. The reason why the electron stripping blade is so favoured, despite the many disadvantages and flaws in that theory to even explain canon events, is that it explains the most important feature of a lightsabre. That it is not hot. It doesn't work by using 100MW of energy in the blade to cut things. It dumps 100MW of energy into the target, but the heat was caused by the object, not by the lightsabre.

Just compare a electric circuit for a single lightbulb as opposed to a circuit with two lightbulbs in series. Which has more energy being converted to light, even though both are being run off a single 1.5V battery?

I'm not saying it releases energy (other than visible light) into the air. I'm saying it's separated from the air by a forcefield that's too weak (by design) to prevent interaction with solids. It touches solids, the forcefield is breached where it touches, and energy leaves the blade and starts going into the solid.

Then you're advocating the plasma forcefield theory. IIRC, the main flaw with that theory was dual. Where did the plasma come from, how is it stored in such a manner that can repulse lightsabres and blasters?

That's a useful analogy if you're talking about heat moving from one object to another. Not radiant energy. Heat moves from a hotter object to a cooler one. Radiant energy moves until hindered by something non-transparent to it.

How many times must I repeat that lightsabres are not hot? That's right, this the third time, and I'm not the first one to say that either.

Also, don't be an idiot. Energy is radiated until the state of the bar is at equivalence with its surrondings. It still follows the laws of thermodynamics.

What about 'the molecules' prevents lasers from interacting with air? Not that it matters - transparency is (by definition) what allows visible light to move through matter. Nor did I say that air's thermal conductivity lets lasers move through it (especially considering air has lousy thermal conductivity compared to most solids but interferes with lasers far less). A vacuum, for example, has no thermal conductivity whatsoever but is the perfect environment for light to travel through unhindered.

1. IIRC, the size, state of air molecules has the bonds being too weak to interact significantly with air, unlike solid state metals where the energy from the beam interacts through transference. Air interacts with the laser when a photon of the right energy level excites it.

[Spanky The Dolphin]

Also note that the glow surrounding the core isn't part of a magical forcefield: it's most likely air molecules reacting to proximity to the cutting core (similar to how ray sheilds glow in atmosphere). In theory the halo would not be visible if the lightsabre was activated in vacuum, but I don't know if such an occurence has ever been documented or specified in the EU.

The "plasma forcefield" theory reminds me of the commonly accepted theory for beam saber operation from Gundam: where plasma is contained inside of a shaped electromagnetic "bottle", which is surrounded by an I-field (latice of Minovsky particles, which only blocks other I-fields). The problem is that a similar theory applied to lightsabre operation contradicts Canon and EU facts and evidence.

[PainRack]

The "plasma forcefield" theory reminds me of the commonly accepted theory for beam saber operation from Gundam: where plasma is contained inside of a shaped electromagnetic "bottle", which is surrounded by an I-field (latice of Minovsky particles, which only blocks other I-fields). The problem is that a similar theory applied to lightsabre operation contradicts Canon and EU facts and evidence.

All lightsabre theories contradict canon facts alone, much less EU.

[Metrion Cascade]

What's the difference? Equal amounts. Dissipated differently, but there should still be some heating of surrounding objects if 100 MW of radiant energy are being released omnidirectionally.

Let me try saying this in another way.

The lightsabre, does not automatically has 100MW of power in that blade. And no, its not a low power settings type of question. The reason why the electron stripping blade is so favoured, despite the many disadvantages and flaws in that theory to even explain canon events, is that it explains the most important feature of a lightsabre. That it is not hot. It doesn't work by using 100MW of energy in the blade to cut things. It dumps 100MW of energy into the target, but the heat was caused by the object, not by the lightsabre. Just compare a electric circuit for a single lightbulb as opposed to a circuit with two lightbulbs in series. Which has more energy being converted to light, even though both are being run off a single 1.5V battery?

Read the topic:

*ahem* you cannot strip electrons from an atom without supplying the necessary energy to make up the difference in electrical potential energy states. That pesky First Law of Thermodynamics again.

I don't expect to hear that electron stripping shit again. At least not in reference to why objects touched by a lightsabre get hot. It has to heat them even if it's stripping electrons. And how do you propose dumping 100MW into such a wide variety of materials without directly heating any of them? What form could radiant energy take to let 100MW of it hit an object and not heat it?

I'm not saying it releases energy (other than visible light) into the air. I'm saying it's separated from the air by a forcefield that's too weak (by design) to prevent interaction with solids. It touches solids, the forcefield is breached where it touches, and energy leaves the blade and starts going into the solid.

Then you're advocating the plasma forcefield theory. IIRC, the main flaw with that theory was dual. Where did the plasma come from, how is it stored in such a manner that can repulse lightsabres and blasters?

Strawman. I never said there was any plasma in the blade. I'm saying the blade is a set of forcefields restraining pure radiant energy.

That's a useful analogy if you're talking about heat moving from one object to another. Not radiant energy. Heat moves from a hotter object to a cooler one. Radiant energy moves until hindered by something non-transparent to it.

How many times must I repeat that lightsabres are not hot? That's right, this the third time, and I'm not the first one to say that either.

And I said the same thing. Radiant energy is not heat. And even that radiant energy doesn't heat air because only the visible part leaves the blade. Until it touches a solid. Then the forcefield opens where it's touching, and the radiant energy is released into the object.

Also, don't be an idiot. Energy is radiated until the state of the bar is at equivalence with its surrondings. It still follows the laws of thermodynamics.

Wrong. There is no such thing as radiant energy potential difference. Potential difference is due to a form of energy (such as electricity or molecular KE or gravitational potential energy) that's inclined to spread according to where the lower energy state is, and is in matter capable of multiple energy states. Photons don't have multiple energy states, and there is no medium for them. A laser beam fired at the Sun won't suddenly backfire and draw the Sun's radiation back along the beam into your pointer until the pointer and the Sun are the same temperature. Why? Because no medium causes photons to interact with each other, and light isn't looking to move to a lower energy state because it can't. You're thinking of heat.

What about 'the molecules' prevents lasers from interacting with air? Not that it matters - transparency is (by definition) what allows visible light to move through matter. Nor did I say that air's thermal conductivity lets lasers move through it (especially considering air has lousy thermal conductivity compared to most solids but interferes with lasers far less). A vacuum, for example, has no thermal conductivity whatsoever but is the perfect environment for light to travel through unhindered.

1. IIRC, the size, state of air molecules has the bonds being too weak to interact significantly with air, unlike solid state metals where the energy from the beam interacts through transference. Air interacts with the laser when a photon of the right energy level excites it.

Yes, but air is sufficiently spread out that most of a beam doesn't hit its molecules. That's why we can't see it until it hits dust or something else that spreads it out more. And remember - with lasers what you see is what you get. Lasers are nothing but visible light. If the photons in the beam were hitting the air frequently enough to heat it, they'd also be hitting it enough for the beam to be visible as they scattered.

[Metrion Cascade]

More problems with the potential difference bit:

- it requires the lightsabre blade to be composed of matter. Heat and electricity can only move from matter to matter. In other words the potential difference theory is actually more consistent with the "plasma forcefield" idea than my stance is.

- it would make lightsabres useless against forcefields (which IIRC they aren't). For the potential difference bit to work, the target has to be composed of matter which is at a lower temperature than the blade or has a lower voltage. Forcefields have no matter at all, so the blade wouldn't release any energy into them if it needed a potential difference. Only the momentum of the matter in the blade hitting the forcefield would be transferred into it, along with the KE transmitted by the swing and whatever interference there is between the target forcefield and the blade's forcefield. Unless the blade's forcefield is more powerful than the target forcefield (it can't be, because the plasma has to be released on contact with solids and that requires a weak forcefield), no damage would ensue.

- the plasma (required for a potential difference mechanism) is fluid at a far higher energy state than the atmosphere. It would explode the minute the blade touched anything, killing the user along with the target.

EDIT - some clarifications about the blade/forcefield interaction. Added bit about plasma being fluid.

[PainRack]

Read the topic:

*ahem* you cannot strip electrons from an atom without supplying the necessary energy to make up the difference in electrical potential energy states. That pesky First Law of Thermodynamics again.

I don't expect to hear that electron stripping shit again. At least not in reference to why objects touched by a lightsabre get hot. It has to heat them even if it's stripping electrons. And how do you propose dumping 100MW into such a wide variety of materials without directly heating any of them? What form could radiant energy take to let 100MW of it hit an object and not heat it?

Ahem, let me correct you one more time again on your physics.

MW is replying to the suggestion that the lightsabre doesn't work in a DET, not to the suggestion that the lightsabre isn't hot.

The lightsabre has to supply energy into the matter. I never said that it doesn't have to. HOWEVER, there is nothing to say that the lightsabre is dumping out 100MW of energy at all times into every material. Indeed, canon material says it does not.

Again, heat is not equivalent to energy. Get that fact right before we continue with this basic physics lesson. Heat at most is defined by how much internal energy an object has.

Strawman. I never said there was any plasma in the blade. I'm saying the blade is a set of forcefields restraining pure radiant energy.

Energy cannot be restrained by forcefields. Please define "radiant" energy then.

And I said the same thing. Radiant energy is not heat. And even that radiant energy doesn't heat air because only the visible part leaves the blade. Until it touches a solid. Then the forcefield opens where it's touching, and the radiant energy is released into the object.

Define radiant energy . It would appear that my notion that you are talking about EM energy is clearly false.

Wrong. There is no such thing as radiant energy potential difference. Potential difference is due to a form of energy (such as electricity or molecular KE or gravitational potential energy) that's inclined to spread according to where the lower energy state is, and is in matter capable of multiple energy states. Photons don't have multiple energy states, and there is no medium for them. A laser beam fired at the Sun won't suddenly backfire and draw the Sun's radiation back along the beam into your pointer until the pointer and the Sun are the same temperature. Why? Because no medium causes photons to interact with each other, and light isn't looking to move to a lower energy state because it can't. You're thinking of heat.

1. Photons do have multiple energy states. They're defined by e=hf.

2. There is a medium. Its called an EM wave. EM energy travels along the EM wave.

3. A laser beam doesn't absorb energy because its not matter(using classical physics). I haven't heard of how to add energy to an Electromagnetic wave yet............ but that's more a limit of my knowledge than whether or not its possible or not.

Energy isn't inclined to do anything. The Greeks notion of "objects are inclined to move in circles" has been ignored for quite a long time now.

Yes, but air is sufficiently spread out that most of a beam doesn't hit its molecules. That's why we can't see it until it hits dust or something else that spreads it out more. And remember - with lasers what you see is what you get. Lasers are nothing but visible light. If the photons in the beam were hitting the air frequently enough to heat it, they'd also be hitting it enough for the beam to be visible as they scattered.

.......Duh.........

[PainRack]

Just to prevent any more misunderstanding about heat and lightsabres, just answer this following question.


When you stick your hand out under a suntan lamp, presumably, your hand will begin to feel warm after a while. Conduction is neglible, as air is an insulator. we shall assume convection is insignificant. So, the only avenue left is UV light, EM energy.

Is UV light then hot?

[Metrion Cascade]

Just to prevent any more misunderstanding about heat and lightsabres, just answer this following question.


When you stick your hand out under a suntan lamp, presumably, your hand will begin to feel warm after a while. Conduction is neglible, as air is an insulator. we shall assume convection is insignificant. So, the only avenue left is UV light, EM energy.

Is UV light then hot?

When did I say lightsabre blades are matter?

[Metrion Cascade]

I'll concede that I shouldn't have called lightsabres "hot," as even I wasn't thinking of them as matter. But they do directly release energy into what they touch, and that energy heats the target.

[Metrion Cascade]

Well, this is funny...looks like PainRack and I primarily disagree on the words "hot" and "heat" (admittedly, misnomers).

Read the topic:

*ahem* you cannot strip electrons from an atom without supplying the necessary energy to make up the difference in electrical potential energy states. That pesky First Law of Thermodynamics again.

I don't expect to hear that electron stripping shit again. At least not in reference to why objects touched by a lightsabre get hot. It has to heat them even if it's stripping electrons. And how do you propose dumping 100MW into such a wide variety of materials without directly heating any of them? What form could radiant energy take to let 100MW of it hit an object and not heat it?

Ahem, let me correct you one more time again on your physics.

MW is replying to the suggestion that the lightsabre doesn't work in a DET, not to the suggestion that the lightsabre isn't hot.

Conceded, DET doesn't mean something is "hot," since only matter can be hot relative to other matter.

The lightsabre has to supply energy into the matter. I never said that it doesn't have to. HOWEVER, there is nothing to say that the lightsabre is dumping out 100MW of energy at all times into every material. Indeed, canon material says it does not.

Agreed. Which, to me, means that (a) the energy released is proportional to how much of the blade is in contact with the target, (b) there are multiple power settings on a lightsabre, or (c) both.

Again, heat is not equivalent to energy. Get that fact right before we continue with this basic physics lesson. Heat at most is defined by how much internal energy an object has.

Strawman. I never said there was any plasma in the blade. I'm saying the blade is a set of forcefields restraining pure radiant energy.

Energy cannot be restrained by forcefields. Please define "radiant" energy then.

EM energy. And if EM energy can't be restrained by forcefields (assuming you're referring to EM energy), explain why things like lasers are stopped by sufficiently strong shields.

And I said the same thing. Radiant energy is not heat. And even that radiant energy doesn't heat air because only the visible part leaves the blade. Until it touches a solid. Then the forcefield opens where it's touching, and the radiant energy is released into the object.

Define radiant energy . It would appear that my notion that you are talking about EM energy is clearly false.

That's what I'm talking about.

Wrong. There is no such thing as radiant energy potential difference. Potential difference is due to a form of energy (such as electricity or molecular KE or gravitational potential energy) that's inclined to spread according to where the lower energy state is, and is in matter capable of multiple energy states. Photons don't have multiple energy states, and there is no medium for them. A laser beam fired at the Sun won't suddenly backfire and draw the Sun's radiation back along the beam into your pointer until the pointer and the Sun are the same temperature. Why? Because no medium causes photons to interact with each other, and light isn't looking to move to a lower energy state because it can't. You're thinking of heat.

1. Photons do have multiple energy states. They're defined by e=hf.

Photons going from having one amount of energy to having another?

2. There is a medium. Its called an EM wave. EM energy travels along the EM wave.

That wave is a particle - a quantum of energy. It isn't a medium for itself.

3. A laser beam doesn't absorb energy because its not matter(using classical physics). I haven't heard of how to add energy to an Electromagnetic wave yet............ but that's more a limit of my knowledge than whether or not its possible or not.

So photons don't have energy states in the same sense as matter, in which one particle can have more energy than another, allowing potential differences between one object and another.

[CaptainChewbacca]

In Shadows of the Empire when Luke first turned on his lightsaber, he held his hand up to it. He noted that it was good that there was no heat, since a lightsaber wasn't supposed to radiate any heat.

[Howedar]

The ANH novellization also states that there is no head radiated, IIRC.

[Spanky The Dolphin]

That's what I said back when the thread started. Though I said "generate" rather than "radiate," so that probably changed it.