Why don't lightsabres make people explode?

[Winston Blake]

I understand that this isn't the case, but why is that? What effect on the crystal's temperature does all that light have? Is the heat that's carried away by a high-powered laser's cooling system just the waste that doesn't make it from the electrical power supply to the beam?

I don't quite follow you. The power supply is the input, the laser beam is the output, 100% efficiency is impossible, and the waste heat is carried away by the cooling system. What other heat could it be carrying away?

And is there some other term besides "heat" we can use for what radiant energy does to matter?

Depends on the frequency. Radio waves can induce current, infrared heats stuff up, gamma rays ionise atoms, etc.

I guess you could just say "transfer energy to".

[Metrion Cascade]

I understand that this isn't the case, but why is that? What effect on the crystal's temperature does all that light have? Is the heat that's carried away by a high-powered laser's cooling system just the waste that doesn't make it from the electrical power supply to the beam?

I don't quite follow you. The power supply is the input, the laser beam is the output, 100% efficiency is impossible, and the waste heat is carried away by the cooling system. What other heat could it be carrying away?

I can't imagine.

And is there some other term besides "heat" we can use for what radiant energy does to matter?

Depends on the frequency. Radio waves can induce current, infrared heats stuff up, gamma rays ionise atoms, etc.

I guess you could just say "transfer energy to".

Thanks.

[Darth Wong]

It's gradually been answered, i'll summarise:

-lightsaber blades are enclosed in a weak 'forcefield'

-the forcefield pushes away gases but can't push away solids, so is broken by contact with a target

-this forcefield interacts with the air to make a humming sound

The problems are:

1. Corran attempts to free slaves on Belkadan is meant to be an example of air-heating i think. But we don't have a quote.

2. Tipoca City rain hitting Obi-Wan's lightsaber. Did it interact? If so, why didn't Qui-Gon's bodily fluids explode when he was stabbed?

3. Lightsabers working underwater.

Note: #1 and #3 are only quasi-canon, which means that they can be rejected if they make no sense whatsoever, just as we would do with an historical account that makes no sense, even if it comes from a source that seems credible.

My thoughts:

1. Eithe the blade or it's forcefield heats the air up over a long (how long was it in the novel?) period of time.

It probably does, but not quickly enough to be a hazard.

2. Perhaps Qui-Gon's fluids were vaporising on contact with Maul's blade, but the body fluid vapor was 'pushing away' other fluids as it escaped out the hole. This might limit the blade-viscera interaction, as opposed to blade-metal.

That would not solve the problem of the necessity for vapourizing material in order to create the initial hole. However, it is not immediately clear how large the hole is. If the blade's heating portion is actually much narrower than the visible region (which we might imagine is the forcefield), then it might make a very small hole, thus avoiding the problem of having to vapourize a large volume of material in milliseconds.

3. This would point to a water-repellant strength forcefield, and if Tipoca City had blade-rain interaction, we might say that the hilt has ambient pressure sensors that determine how strong to make the forcefield.

There is no such thing as a universal strength to repel water regardless of circumstance. The total force required to deflect raindrops is much lower than the force required to maintain a vacuum underwater.

[Winston Blake]

There is no such thing as a universal strength to repel water regardless of circumstance. The total force required to deflect raindrops is much lower than the force required to maintain a vacuum underwater.

I assumed that when lightsabers were used underwater, that the hilt was underwater too. Ambient pressure sensors would logically be in the hilt. When used underwater, the hilt sensors are submerged and strengthen the forcefield. The ambient pressure on the Tipoca City platform would have been air-pressure, so IF hissing occurs (i don't have AOTC) then raindrops apply enough pressure to break through an "air pressure strength" forcefield.

[PainRack]

Do you figure that a laser gun should get hot because the laser beam can heat things?

You're the one who's arguing for thermal equivalence, instead of me arguing for specific selectivity.

Perhaps it will help if we go to what hot is. I believe that the lightsabre is not "hot", as in the energy transfer involved is not mechanical/internal in nature. So, if we edge away from deltaq= ?? + ??...........

This isn't about being a "purist"; it's about not being stupid. The notion of a lightsabre having no heating effect on water is fucking stupid and makes no scientific sense whatsoever. Are you going to tell me that I'm also a "purist" because I reject the ridiculous "solar panel" literature interpretation of TIE fighter wings?

Ergo, my noting that lightsabres are selective in nature, and cannot be just a simple matter of energy transfer.

We cannot simply discard evidence because they don't fit in with our theory. Hell, that's the only reason why some people don't laugh directly in my face with the "solar panel"= energy recycler theory.