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@Baronlveagh - your 220MJ is to vapourise 25kg of human. Thats not really a fair comparison to the effects if a bullet, or even the described effects of a lasgun. Some part of the surface of the target will be vapourised but its more likely that thermal shock and differential thermal expansion would cause most damage. 6kW industrial lasers can cut through 10mm of steel at a rate of 1cm/s and they are allegedly only 15% efficient and run on a continuous beam. I see no reason why magical future tech for batteries and focussing arrays couldn't develop an effective laser rifle.

Also remember that the 747 YAL1 noted above somewhere was specified to cripple targets at a range of 300 to 600km, again a rather unfair comparison to an infantry small arm.

 BaronIveagh wrote:

 Kain wrote:
Same way that the stormraven flies probably.

I attribute that whole mess to GW's inability to make realistic minis in general.

I'd rather have a flying brick than an F22 in space.

We're still going on about how a fictional weapon from the far, FAR future fonctions on concepts that even the citizens on that far, FAR away future doesn't know as it is taboo and heretical to even look at the inner workings of any technological device?

No seriously, that is like trying to explain how a light saber from Star Wars works; it works because it does.
It does X because they wrote that it does X, not because of real SCIENCE.

Why don't we talk about how a Leman Russ engine can works on fuel composed of any or all following liquids at any time, ever.
potato oil
gasoline
Kerosene
prometium
lamp oil
pitch
whale fat boiled to liquid form
factory grease cut with water

I'm way more interested in that real life situation (dependence of gasoline is rather current event, what with the prices fluctuating every time a Saudi prince farts in the wrong direction) than how a laser rifle works.

Psienesis wrote:
Except it doesn't at all work the way that we think that it does. Lasguns are, one, not beam weapons. They are, at least in some patterns, pulse weapons. It fires a "bolt" of laser energy, not a beam. It should be noted that lasweapons are capable of burst and automatic fire (and not just the multi-barreled multilas) and also have kinetic recoil . Two, las shots are known to have kinetic force behind their heat force, as demonstrated in a number of sources that have targets knocked down, but not injured, by the las shot. Three, las weapons provide very little cauterization to the injuries caused by them. At the point of impact, certainly. Radiating out from that? Flash-cooked flesh, blood turned instantly to steam, great, gory chunks blown out of you by the rapidly-expanding gases that was the water in your flesh.

And several other sources claim they're recoiless. So we attribute that to the GW 'unreliable narrator', along with the 'great gory mess' because other authors describe it as a 'distinctive through and through wound' that bleeds very little due to the cauterization. So, we try try to find common elements Universally, they make a hole in someone, so this gives us a starting point,.

A laser 'beam' firing for 50 milliseconds would appear to be a 'pulse' or 'bolt' to the naked eye, assuming it was visible, so claiming it's not a laser beam because someone 'sees' it not being a beam does not actually mean it's not a beam.

Flinty wrote:@Baronlveagh - your 220MJ is to vapourise 25kg of human. Thats not really a fair comparison to the effects if a bullet, or even the described effects of a lasgun. Some part of the surface of the target will be vapourised but its more likely that thermal shock and differential thermal expansion would cause most damage. 6kW industrial lasers can cut through 10mm of steel at a rate of 1cm/s and they are allegedly only 15% efficient and run on a continuous beam. I see no reason why magical future tech for batteries and focussing arrays couldn't develop an effective laser rifle.

Also remember that the 747 YAL1 noted above somewhere was specified to cripple targets at a range of 300 to 600km, again a rather unfair comparison to an infantry small arm.

The industrial lasers work because they're burning through a very small amount of actual mass, and also require a much longer time to burn through that material than would be practical for a laser infantry weapon (burnign throug ha much, much thicker target in about 50 milliseconds). Remember that the extreme short duration of the shot increases the required power output to achieve the same result. (Again, the point should be mad that YAL-1 does not actually burn through anything, which is what makes it's output a poor comparison.)

While I'm sure with enough fancy focusing arrays you could compensate for atmospheric dispersion, which is the real killer for beam efficiency, you can't overcome the fact that the laser has to impart on the target enough thermal energy to reach 6k degrees kelvin. If you're not worried about penetrating bone or clothing or anything, you can get away with 0.42kJ/cm3 of target being vaporized, but since no one who's not a space marine seems to have a lasgun round deflected by their unaugmented skull, it's probably safe to assume something in the 23.1kJ/cm3 range,

Someone ran the numbers once upon a time for the energy required to vaporize a 1969 Ford Mustang, but it makes a poor comparison for lascannon fire because we don't know how much steel or iron is in a Leman Russ, though both those metals are used in it.

Inquisitor Jex wrote:
No seriously, that is like trying to explain how a light saber from Star Wars works; it works because it does.
It does X because they wrote that it does X, not because of real SCIENCE.

One second, let me break out my irony beam...

http://www.popsci.com/technology/article/2009-10/us-special-forces-field-test-plasma-knife

The only thing I've never been clear on is why they have shadows...

Inquisitor Jex wrote:
Why don't we talk about how a Leman Russ engine can works on fuel composed of any or all following liquids at any time, ever.
potato oil
gasoline
Kerosene
prometium
lamp oil
pitch
whale fat boiled to liquid form
factory grease cut with water

I'm way more interested in that real life situation (dependence of gasoline is rather current event, what with the prices fluctuating every time a Saudi prince farts in the wrong direction) than how a laser rifle works.

Well, promethium is, afaik not real, and the last three it won't burn, but a Heracles Multi fuel engine will burn a pretty broad spectrum of fuels, including, IIRC, kerosene, ethenol, heating oil, gasoline, diesel, jet fuel, and probably lamp oil, but I don't know if anyone ever tried that one.

You know to me the only reason to use lasers in the future as oppessed to more conventional weapons would be because of shields. use the lasers to take down shields then spray and pray with missiles and bullets (probally the mechwarrior in me lol) also sinse a laser beam or even a laser pulse would move at the speed of light it would be inpossible to dodge the actual shot, if you were to try to dodge it would have to be before the triggers pulled. Also i once watched on science channel about how to build your own light saber, and it is realisticly possible in the near future to build one of close faxcimily, it would be plasma based though. But the relavent part is nano technology can be used to make the power source, by making basicly millions of miniture battaries and capaciters. of course this technology currently needs 0 gravity enviroment to create, but hey they are in the future in space. But still lasers are very ineffecient weapons. I much prefer the basic troop weapons of the starcraft universe marines the inpaler rifle.

Yeah like that plasma scalpel will be a meter in length.

and I think they called it a welding torch in another field.

So it is not a light saber, not even close.

Besides, they wrote that Leman Russes work on any and all fuel types, even things that are not fuel, partially why it is the main battle tank of the Guard, despite being slow a rock. so yeah those last 3 will burn in a leman russ engine.

And several other sources claim they're recoiless. So we attribute that to the GW 'unreliable narrator', along with the 'great gory mess' because other authors describe it as a 'distinctive through and through wound' that bleeds very little due to the cauterization. So, we try try to find common elements Universally, they make a hole in someone, so this gives us a starting point,.

You could attribute it to that, but you'd be wrong to do so. You're cherry-picking data to make it conform to the idea that you can quantify how it functions while ignoring all of the additional data that doesn't fit with your hypothesis. That's simply bad science.

A laser 'beam' firing for 50 milliseconds would appear to be a 'pulse' or 'bolt' to the naked eye, assuming it was visible, so claiming it's not a laser beam because someone 'sees' it not being a beam does not actually mean it's not a beam.

Except they can and do deflect off certain metal surfaces, and are described as a ball or short rod of light bouncing around in the air, and characters can and do dodge them. Can't dodge a beam by weaving around it.

Yay! Someone else linked Project Rho...I was going to but I figured I better not for common decency's sake. I credit that website for about 75% of what I know about potential spacecraft tech. Spent an entire weekend binging on that site because I wanted to write a realistic near future sci-fi story for a creative writing class. The rest of the class absolutely hated it because of all the tech detail I put in, but there you go

Interesting to know about the YAL's method of operation. I always assumed it worked similar to the Navy proposed laser (I prefer the railgun project personally, but lasers are cool and they get funding). Good to hear they figured smaller spot size would do the job better.

Complete side note, but one of my teachers at university is actually doing a ton of research about how to account for laser distortion in turbulent air to maintain a consistent beam. I wouldn't be surprised at all to hear he had something to do with that project. Apparently the guy worked for NASA and the Air Force quite a bit over his career (he has space shuttle programs on punch cards in boxes in his basement...)

At the moment I am satisfied that some kind of personal laser weapon has the potential to exist with near future tech, but it will not be more practical than kinetic weapons without some major scientific breakthroughs, and even then it will almost certainly never work as well as a lasgun.

 Psienesis wrote:

And several other sources claim they're recoiless. So we attribute that to the GW 'unreliable narrator', along with the 'great gory mess' because other authors describe it as a 'distinctive through and through wound' that bleeds very little due to the cauterization. So, we try try to find common elements Universally, they make a hole in someone, so this gives us a starting point,.

You could attribute it to that, but you'd be wrong to do so. You're cherry-picking data to make it conform to the idea that you can quantify how it functions while ignoring all of the additional data that doesn't fit with your hypothesis. That's simply bad science.

A laser 'beam' firing for 50 milliseconds would appear to be a 'pulse' or 'bolt' to the naked eye, assuming it was visible, so claiming it's not a laser beam because someone 'sees' it not being a beam does not actually mean it's not a beam.

Except they can and do deflect off certain metal surfaces, and are described as a ball or short rod of light bouncing around in the air, and characters can and do dodge them. Can't dodge a beam by weaving around it.

But you could dodge the actual pull of the trigger giving the illusion that your dodging something that moves at the speed of light.

 Psienesis wrote:

You could attribute it to that, but you'd be wrong to do so. You're cherry-picking data to make it conform to the idea that you can quantify how it functions while ignoring all of the additional data that doesn't fit with your hypothesis. That's simply bad science.

Not really. Whether or not it has recoil is inconsistent, occasionally in the same book, if not on the same page. Science depends on consistent, reliable data, which we have very little of for this subject. What we do have that is consistent is that it will make a hole in a human being, apparently regardless of hit location. So we use the energy requirements to do that as our 'low end', since we cannot test the actual burn properties of their armor or clothing.

Further, you mention knock down, but this could also be attributed to shock, as happens with small caliber real world projectiles, where it is not the kinetic energy, but rather the body's response to the shock, that knocks the subject prone.

 Psienesis wrote:

Except they can and do deflect off certain metal surfaces, and are described as a ball or short rod of light bouncing around in the air, and characters can and do dodge them. Can't dodge a beam by weaving around it.

Characters also jump between space ships tens of thousands of kilometers apart who are not matching orbital velocities and manage to land on their target while 'eyeballing it' and weave between the fire of a HMG firing full auto, and survive orbital strikes in the gigaton range within a hundred yards of ground zero, when they would have been reduced to a carbon smear and water vapor, no matter how badass their armor is, because they were not wearing their helmets. (No amount of genetic engineering makes the bonds between your water molecules tougher, as that's not controlled by DNA...).

And since all these things are inconsistent within the setting, we go with what we know to be consistent.

 starraptor wrote:

But you could dodge the actual pull of the trigger giving the illusion that your dodging something that moves at the speed of light.

That's pretty much how you dodge bullets in real life. You don't actually dodge the bullet, you simply avoid where they're pointing the gun.

I can tell you guys that in surgery, electrocautery has two different settings: cut, and coagulate. Coag is used to quickly cauterize bleeders without doing excessive damage to surrounding tissue. The cut setting is more intense and is used like a knife to cut through tissue (muscle, fat, fascia, etc.). It does not cauterize very effectively as it's cutting.
The scalpel is typically only used to cut skin (because skin blisters under cautery and would ruin the incision, making suturing ugly.) Although, there is a more expensive alternative called a Plasma Knife which can cut skin without blistering and, in fact, does equivalent residual tissue damage to the scalpel's mechanical crush zone, while cauterizing. But as far as I've seen, surgeons still prefer the bovie for faster, more wide-spread cauterization.

What I'm saying is that despite what light sabers show us, cutting through tissue with heat is not necessarily going to effectively cauterize at the same time. Certainly not the larger blood vessels in any case.

 BaronIveagh wrote:

Flinty wrote:@Baronlveagh - your 220MJ is to vapourise 25kg of human. Thats not really a fair comparison to the effects if a bullet, or even the described effects of a lasgun. Some part of the surface of the target will be vapourised but its more likely that thermal shock and differential thermal expansion would cause most damage. 6kW industrial lasers can cut through 10mm of steel at a rate of 1cm/s and they are allegedly only 15% efficient and run on a continuous beam. I see no reason why magical future tech for batteries and focussing arrays couldn't develop an effective laser rifle.

Also remember that the 747 YAL1 noted above somewhere was specified to cripple targets at a range of 300 to 600km, again a rather unfair comparison to an infantry small arm.

The industrial lasers work because they're burning through a very small amount of actual mass, and also require a much longer time to burn through that material than would be practical for a laser infantry weapon (burnign throug ha much, much thicker target in about 50 milliseconds). Remember that the extreme short duration of the shot increases the required power output to achieve the same result. (Again, the point should be mad that YAL-1 does not actually burn through anything, which is what makes it's output a poor comparison.)

While I'm sure with enough fancy focusing arrays you could compensate for atmospheric dispersion, which is the real killer for beam efficiency, you can't overcome the fact that the laser has to impart on the target enough thermal energy to reach 6k degrees kelvin. If you're not worried about penetrating bone or clothing or anything, you can get away with 0.42kJ/cm3 of target being vaporized, but since no one who's not a space marine seems to have a lasgun round deflected by their unaugmented skull, it's probably safe to assume something in the 23.1kJ/cm3 range,

Someone ran the numbers once upon a time for the energy required to vaporize a 1969 Ford Mustang, but it makes a poor comparison for lascannon fire because we don't know how much steel or iron is in a Leman Russ, though both those metals are used in it.

I was thinking about this more last night and I still think the requirement to vaiourise the flesh is too onerous. given that we're 70-80% water, all you need to do is flash-boil the water and that would cause all sorts of explosive and thermal damage to a human target. Flash boiling a kg of water would appear to take about 2.5MJ and the 1600x expansion from water to steam would cause plenty of damage to the target. Vapourisation of smaller volumes of water would requite proortionally less energy and still likely cause sufficient damage to disable a person.

Orks are regularly described as having small arms fire bounce off their skulls.

Also to those who wonder why we're not developing laser weapons for infantry at this time, I remember reading somewhere that anti-infantry lasers contravene the Geneva Convention as they are much more likely to blind than kill. Weapons that are expressley designed to disable but not kill are banned. If you're having a war you need to at least be trying to kill the opponent's soldiers

 BaronIveagh wrote:

Inquisitor Jex wrote:
Why don't we talk about how a Leman Russ engine can works on fuel composed of any or all following liquids at any time, ever.
potato oil
gasoline
Kerosene
prometium
lamp oil
pitch
whale fat boiled to liquid form
factory grease cut with water

I'm way more interested in that real life situation (dependence of gasoline is rather current event, what with the prices fluctuating every time a Saudi prince farts in the wrong direction) than how a laser rifle works.

Well, promethium is, afaik not real, and the last three it won't burn, but a Heracles Multi fuel engine will burn a pretty broad spectrum of fuels, including, IIRC, kerosene, ethenol, heating oil, gasoline, diesel, jet fuel, and probably lamp oil, but I don't know if anyone ever tried that one.

I'm also pretty sure that a lot of modern tanks with diesel engines can burn a wide range of fuel types, down to wood spirit in an emergency. Sure it will knacker the engine, but it might just give you enough movement to be useful.

 Archonate wrote:
I can tell you guys that in surgery, electrocautery has two different settings: cut, and coagulate. Coag is used to quickly cauterize bleeders without doing excessive damage to surrounding tissue. The cut setting is more intense and is used like a knife to cut through tissue (muscle, fat, fascia, etc.). It does not cauterize very effectively as it's cutting.
The scalpel is typically only used to cut skin (because skin blisters under cautery and would ruin the incision, making suturing ugly.) Although, there is a more expensive alternative called a Plasma Knife which can cut skin without blistering and, in fact, does equivalent residual tissue damage to the scalpel's mechanical crush zone, while cauterizing. But as far as I've seen, surgeons still prefer the bovie for faster, more wide-spread cauterization.

What I'm saying is that despite what light sabers show us, cutting through tissue with heat is not necessarily going to effectively cauterize at the same time. Certainly not the larger blood vessels in any case.

Unless a light saber is basicly a handle that when turned on releases a super tough heat resistent nano carbon tube filled with plasma, then in fact it would burn and cauterize very effectivly. It would basicly make it a industrial grade blow torch in the shape of a sword.

 Flinty wrote:

I was thinking about this more last night and I still think the requirement to vaiourise the flesh is too onerous. given that we're 70-80% water, all you need to do is flash-boil the water and that would cause all sorts of explosive and thermal damage to a human target. Flash boiling a kg of water would appear to take about 2.5MJ and the 1600x expansion from water to steam would cause plenty of damage to the target. Vapourisation of smaller volumes of water would requite proortionally less energy and still likely cause sufficient damage to disable a person.

Orks are regularly described as having small arms fire bounce off their skulls.

Sadly, we can't test an ork skull to determine why that is, though the implication is that it's because of bone density, but it could be due to ork having a different chemical composition to their bone structure.

Otherwise....first, that number is for pure water. Remember that the boiling point of water changes depending on what you add to it, and the target is only 70-80% water. That remaining 20-30% will throw the numbers off. Also, I've been avoiding clothing, because we don't know what 'average' far future clothing is made of, but it would mean that even a white cotton t shirt would provide measurable protection from a lasgun (to use an example from an old IG joke) and since I can't find any examples of someone's unenhanced dungarees stopping a lasgun round..

One of the more interesting injuries from a lasgun in 40k fiction that I've been able to find is Jinxie Penlan's injury in the first CC novel. A near miss gives her a flash burn on the side of her face strong enough to give her a noticeable scar, even several years later as the series progresses. I haven't been able to find an example that contradicts this, but definitely sounds like there's a small amount of beam dispersion going on, because the shot would be too short lived for convection to cause enough heating to burn someone. We can't say for sure, because we don't know how close the shot was, but it's interesting.

 starraptor wrote:

 Archonate wrote:
I can tell you guys that in surgery, electrocautery has two different settings: cut, and coagulate. Coag is used to quickly cauterize bleeders without doing excessive damage to surrounding tissue. The cut setting is more intense and is used like a knife to cut through tissue (muscle, fat, fascia, etc.). It does not cauterize very effectively as it's cutting.
The scalpel is typically only used to cut skin (because skin blisters under cautery and would ruin the incision, making suturing ugly.) Although, there is a more expensive alternative called a Plasma Knife which can cut skin without blistering and, in fact, does equivalent residual tissue damage to the scalpel's mechanical crush zone, while cauterizing. But as far as I've seen, surgeons still prefer the bovie for faster, more wide-spread cauterization.

What I'm saying is that despite what light sabers show us, cutting through tissue with heat is not necessarily going to effectively cauterize at the same time. Certainly not the larger blood vessels in any case.

Unless a light saber is basicly a handle that when turned on releases a super tough heat resistent nano carbon tube filled with plasma, then in fact it would burn and cauterize very effectivly. It would basicly make it a industrial grade blow torch in the shape of a sword.

Your abundant use of the word 'basically' betrays the fictitious substance of your point.

Philosophical conjectures aside, I'm talking about something real as a comparison for how something hypothetical might work.

In surgery, for cutting, a continuous single frequency sine wave is often employed. Rapid tissue heating leads to explosive vaporization of interstitial fluid. If the voltage is sufficiently high (> 400 V peak-to-peak) the vapor sheath is ionized, forming conductive plasma. Electric current continues to flow from the metal electrode through the ionized gas into the tissue. Rapid overheating of tissue results in its vaporization, fragmentation and ejection of fragments, allowing for tissue cutting. The vaporization is why a hotter electrode doesn't cauterize.

For coagulation, the average power is typically reduced below the threshold of cutting. Typically, sine wave is turned on and off in a rapid succession. The overall effect is a slower heating process, which causes tissue to coagulate. (Coagulate = cauterize, btw.)

It always amused me that a guardsman can punch just as strong as his lasgun fires.

 lord of corn wrote:
It always amused me that a guardsman can punch just as strong as his lasgun fires.

It probably involves using knives and close combat type weapons.

KICK EM IN DA BALLS.

The following calc probably needs checking as I'm not a laser expert.

Coming at it from the other way, incident radiation of 150kW/sq.m has been proven to cause full depth skin burns in 4s (testing that must have been fun...). Bump the power up an order of magnitude to compress the time required for serious damage to human flesh (and for fun) and put the target at 1km (a reasonable assumption for maximum effective range for firearms).

According to the calculation method for laser safety, you would require a 12kW laser (measured at aperture) to get a target irradiance of 1.5MW/sq.m, provided the beam spread is low enough that it strikes a 0.01sq.m area of the target. This level of irradiance is more than enough to ignite solid materials and punch through clothing/armour on a target (Piloted ignition of wood, for example, only needs about 12.5kW/sq.m). Atmospheric losses would need to be taken into account.

This actually puts it inabout the right ball-park if you consider that the Tactical Airborne Laser that was tested a few years ago that is in the 100kW range and "defeated a ground target" at a range of 20km.

In terms of energy consumption, if we call our magical future laser systems 50% efficient (rather than the 25-30% efficiency in modern lasers) and call an individual shot 0.5s long (to get a similar amount of energy into the target compared to the 150kW/sq.m for 4 s), then we need 12kJ per shot. This is enough energy to flash boil approximately 5g of water. For battery storage for 100 shots we would need 1.2MJ storage compared to modern lithium ion battery energy density of 0.9 to 2.63MJ/litre.

So I'm not sure what I've proven with all of this, but it looks like if we could get a small enough and efficient enough laser then modern battery technology would be sufficient to power something that would cause harm to a person at about 1km range. Add in a few magical space materials and the effectiveness of the system goes up.

Another relevant reference is this work on pulsed energy projectile weapons. http://en.wikipedia.org/wiki/Pulsed_Energy_Projectile


Automatically Appended Next Post:

 lord of corn wrote:
It always amused me that a guardsman can punch just as strong as his lasgun fires.

This is when the rules abstractions come in again. Over a given (relatively short period of) time, a guardsman is just as likely to kill an enemy with his rifle as he is with his close combat abilities. This seems reasonable as you usually have to fire quite a lot of rifle ammunition before you get an effective hit on a target at range as opposed to stabbing them in the face.

 Flinty wrote:
The following calc probably needs checking as I'm not a laser expert.

Coming at it from the other way, incident radiation of 150kW/sq.m has been proven to cause full depth skin burns in 4s (testing that must have been fun...). Bump the power up an order of magnitude to compress the time required for serious damage to human flesh (and for fun) and put the target at 1km (a reasonable assumption for maximum effective range for firearms).

According to the calculation method for laser safety, you would require a 12kW laser (measured at aperture) to get a target irradiance of 1.5MW/sq.m, provided the beam spread is low enough that it strikes a 0.01sq.m area of the target. This level of irradiance is more than enough to ignite solid materials and punch through clothing/armour on a target (Piloted ignition of wood, for example, only needs about 12.5kW/sq.m). Atmospheric losses would need to be taken into account.

This actually puts it inabout the right ball-park if you consider that the Tactical Airborne Laser that was tested a few years ago that is in the 100kW range and "defeated a ground target" at a range of 20km.

''

You're not raising power enough to compensate for time. The time that it has to delver that energy is measured in milliseconds, because the natural movement of the human body, both at of the firer and that of the target, even at rest, will mean the laser does not stay on target long enough.

Some interesting video.




This is a 15kw laser weapon firing, so smaller by an order of magnitude. Notice how long it takes to ignite the target at range.

 Archonate wrote:

 starraptor wrote:

 Archonate wrote:
I can tell you guys that in surgery, electrocautery has two different settings: cut, and coagulate. Coag is used to quickly cauterize bleeders without doing excessive damage to surrounding tissue. The cut setting is more intense and is used like a knife to cut through tissue (muscle, fat, fascia, etc.). It does not cauterize very effectively as it's cutting.
The scalpel is typically only used to cut skin (because skin blisters under cautery and would ruin the incision, making suturing ugly.) Although, there is a more expensive alternative called a Plasma Knife which can cut skin without blistering and, in fact, does equivalent residual tissue damage to the scalpel's mechanical crush zone, while cauterizing. But as far as I've seen, surgeons still prefer the bovie for faster, more wide-spread cauterization.

What I'm saying is that despite what light sabers show us, cutting through tissue with heat is not necessarily going to effectively cauterize at the same time. Certainly not the larger blood vessels in any case.

Unless a light saber is basicly a handle that when turned on releases a super tough heat resistent nano carbon tube filled with plasma, then in fact it would burn and cauterize very effectivly. It would basicly make it a industrial grade blow torch in the shape of a sword.

Your abundant use of the word 'basically' betrays the fictitious substance of your point.

Philosophical conjectures aside, I'm talking about something real as a comparison for how something hypothetical might work.

In surgery, for cutting, a continuous single frequency sine wave is often employed. Rapid tissue heating leads to explosive vaporization of interstitial fluid. If the voltage is sufficiently high (> 400 V peak-to-peak) the vapor sheath is ionized, forming conductive plasma. Electric current continues to flow from the metal electrode through the ionized gas into the tissue. Rapid overheating of tissue results in its vaporization, fragmentation and ejection of fragments, allowing for tissue cutting. The vaporization is why a hotter electrode doesn't cauterize.

For coagulation, the average power is typically reduced below the threshold of cutting. Typically, sine wave is turned on and off in a rapid succession. The overall effect is a slower heating process, which causes tissue to coagulate. (Coagulate = cauterize, btw.)

You do relize we are all debating a fictious weapon so i dont get your point. Also I did not mean to say that was what a light saber was (a light saber is basicly a handle that when turned on releases a super tough heat resistent nano carbon tube filled with plasma) what i meant was that is my theory on how to make one with modern day materials. And that if that was how it was made then it would indeed cauterize a wound since plasma is just super heated gas.

 lord of corn wrote:
It always amused me that a guardsman can punch just as strong as his lasgun fires.

Well in Inquisitor a Space marine could kill a Guardsman by throwing a knife at him.

Through a wall.

That's because... Space Marines.

Regardless of *how* it does it, the lasgun of M41 is analogous to the modern assault rifle, in function, application and ubiquity, even though equivalents to the modern assault rifle still exist in M41. Whether firing a solid slug or a beam/bolt/bar/ball of concentrated thermo-kinetic energy, their results on the body of an average human or xeno is pretty much the same.

 Kain wrote:

 lord of corn wrote:
It always amused me that a guardsman can punch just as strong as his lasgun fires.

Well in Inquisitor a Space marine could kill a Guardsman by throwing a knife at him.

Through a wall.

A Space Marine did way more damage throwing his Bolter at someone than actually firing it.

 starraptor wrote:

 Archonate wrote:

 starraptor wrote:

 Archonate wrote:
I can tell you guys that in surgery, electrocautery has two different settings: cut, and coagulate. Coag is used to quickly cauterize bleeders without doing excessive damage to surrounding tissue. The cut setting is more intense and is used like a knife to cut through tissue (muscle, fat, fascia, etc.). It does not cauterize very effectively as it's cutting.
The scalpel is typically only used to cut skin (because skin blisters under cautery and would ruin the incision, making suturing ugly.) Although, there is a more expensive alternative called a Plasma Knife which can cut skin without blistering and, in fact, does equivalent residual tissue damage to the scalpel's mechanical crush zone, while cauterizing. But as far as I've seen, surgeons still prefer the bovie for faster, more wide-spread cauterization.

What I'm saying is that despite what light sabers show us, cutting through tissue with heat is not necessarily going to effectively cauterize at the same time. Certainly not the larger blood vessels in any case.

Unless a light saber is basicly a handle that when turned on releases a super tough heat resistent nano carbon tube filled with plasma, then in fact it would burn and cauterize very effectivly. It would basicly make it a industrial grade blow torch in the shape of a sword.

Your abundant use of the word 'basically' betrays the fictitious substance of your point.

Philosophical conjectures aside, I'm talking about something real as a comparison for how something hypothetical might work.

In surgery, for cutting, a continuous single frequency sine wave is often employed. Rapid tissue heating leads to explosive vaporization of interstitial fluid. If the voltage is sufficiently high (> 400 V peak-to-peak) the vapor sheath is ionized, forming conductive plasma. Electric current continues to flow from the metal electrode through the ionized gas into the tissue. Rapid overheating of tissue results in its vaporization, fragmentation and ejection of fragments, allowing for tissue cutting. The vaporization is why a hotter electrode doesn't cauterize.

For coagulation, the average power is typically reduced below the threshold of cutting. Typically, sine wave is turned on and off in a rapid succession. The overall effect is a slower heating process, which causes tissue to coagulate. (Coagulate = cauterize, btw.)

You do relize we are all debating a fictious weapon so i dont get your point. Also I did not mean to say that was what a light saber was (a light saber is basicly a handle that when turned on releases a super tough heat resistent nano carbon tube filled with plasma) what i meant was that is my theory on how to make one with modern day materials. And that if that was how it was made then it would indeed cauterize a wound since plasma is just super heated gas.

The lasgun is a non-existent weapon based on existing technology. A lightsaber is pure nonsense.

MY point is that cauterization occurs when you apply heat BELOW cutting threshold. Heat ABOVE cutting threshold does not cauterize, it vaporizes.

In a nutshell: If it's cutting through you, then it is not going to cauterize the wound. (This is why the bovie has 'cut' and 'coag' settings. Because you can't do both at the same time.) The same physics would apply to lightsabers if their concept were possible.

Umm pretty sure a lasgun is not based on any existing technology whatso'ever. The creaters of the concept just says its a laser, they did no reaserch on how lasers work in real life and frankly probaly did not care so they make up a few turms and says it does stuff that they think lasers should do from watching old space movies. And also you have to think about this in 40k no one realy knows what most of the tech does in the imperium. They may call it a laser but for all we know it could be concentrated microwave beames. Because they most likely dont know themselves. Than you have to think about this even in modern day earth lots of things names are actually misnomers and are not actually technicly what they are called its just eaiser sometimes to call it an apple sometimes when its really a melon.

 starraptor wrote:
They may call it a laser but for all we know it could be concentrated microwave beames.

Actually we know it's not that. Because the weapon produces light in the visible spectrum. The radiation spewing gun is a totally different weapon.

As far as the nonconstructive comments...


"Yet now that manifest experiences and necessary proofs have shown them to be well grounded, persons exist who would strip the author of his reward without so much as looking at his book, and add the shame of having him pronounced a heretic." - Galileo Galilei, from a letter to the Grand Duchess Christina of Tuscany, 1615.

 starraptor wrote:
Umm pretty sure a lasgun is not based on any existing technology whatso'ever.

The Lasgun is based on laser technology... Which exists... Right now...

It's not a science fiction term. It's an acronym. Light Amplification by Stimulated Emission of Radiation. They are used today in many forms.
We currently use lasers in surgery to burn off warts, turn kidney stones to dust, remove unwanted body hair, slice eyeballs to correct vision, etc.
Somebody even posted a video of a weaponized laser in this very thread.

Yeah, we could make a lasgun right now. It would just be the size of a Boeing 747 and require tons of power.

The laser itself is the simple part, the power source is the problem. Its neither portable nor super efficient.

That's an exaggeration. Did no one read the projectrho link I put in earlier?

 Grey Templar wrote:
Yeah, we could make a lasgun right now. It would just be the size of a Boeing 747 and require tons of power.

The laser itself is the simple part, the power source is the problem. Its neither portable nor super efficient.

If you need a laser with a 600km range, then yes you need something the size of a 747 currently. A weaponised laser effective to 20km has been demonstrated in a Hercules and the US Air Force is now looking for an effective laser small and light enough to fit to a fighter jet as a weapons pod.

If you need something effective out to 1km it doesn't have to be that big.