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 Psienesis wrote:

Water has a specific heat of 4.18J/gK so it takes over 4 Joules to heat 1 gram of water 1 degree K or C
Flesh is only mostly water and has a specific heat of 3.5 J/gk

Assuming bad things happen at boiling, and flesh starts at 30 degrees C, needing to get to 100 to boil it would take 245 Joules to vaporize one gram of flesh.
Steel has a specific heat of .466 so raising its temperature would be easier. You could however need to get it to a higher tempurature to get it to melt. dT= 1350. It requires 629 Joules to melt a gram of Steel.

Lasguns are measured in an energy unit referred to as a "megathule" (18 of them, if I remember my Uplifting Primer). What, exactly, a megathule is, though, is not provided. It is commonly believed, in threads like these, to mean a "mega-joule", but there's nothing to support that other than the fact that they sound the same.

I'm not looking at what a lasgun specifically produced. I was just going into a thought experiment about what a directed energy weapon would need to do to vaporize part of a target and then looking at the same amount of power against a steel plate. I found it interesting so I posted it.

I'm just sharing the information the studio provides to perhaps give you an idea of the technical specifications, with the added bit that there's no real-world translation for the metrics provided. Perhaps one could take average examples of what a lasgun is described as doing, and from that extrapolate how much energy it's putting out and further translate that into a joule rating or whatever.

Whoever that is, though, is going to have to be someone other than me, as I simply have ceased to give a gak.

burning/melting/vaporization as a damage mechanism for lasers is rather inefficient. A series of laser pulses delivered in a very small area (millimeters) and in a fast enough timeframe (micro to nano seconds) will cause small explosions that dig out craters in the material (The exact effect depends on the parameters of the beam and the nature of the material.) Amongst hard scifi circles this has been suggested as a means for a 'realistic' laser weapon, in fact, and it fits with the depiction of lasweapons in many sources (3rd and 6th editions, most notably) and has even been noted as being comparable energy wise to slugthrowers (although the nature of how bullets cause 'wounds' in target make actual comparisons a bit iffy, as many of the more severe damage mechanisms rely on tumbling and/or fragmentation of the bullet as much as projectile mass and velocity.)

I should note this is going to be a not very productive discussion in general unless some sort of commonalities or agreements are hammered out, as we have no real, hard information on how a hypothetical laser weapon would work (or if lasguns actually ARE lasers, which is a whole nother level of argument.) but there is lots of speculation and theory out there (and disagreement/variation on how it is regarded. Big shock amongst sci fi nerds.) So arguing 'what is' true is going to be fruitless unless there is clarification (although that leaves a whole slew of other things that can be argued over, like whether science can be applied to fiction, what sources are and aren't appropriate, divergence in interpretation of text, etc.)

you could use lasers as a heat ray, but due to poor penetration of most wavelenghts as I hear it most people would react in pain and move out of the way before your could heat up and inflict enough thermal damage (unless you use it like some sort of wide-beam laser flamethrower, at least. But most lasweapons tend to be much more localized than this and 'energy flamethrower' is more akin to a melta anyhow.)

Edit: Oh and body armor too. Very complicated as far as protection and resistance ratings and such go (shot placement matters a lot as to success and failure. and even then Manufacturers make explicit mention that no armor can guarantee perfect protection in every circumstance, so it seems very context-dependent.)

In space though, there is no where to dump your heat. Heat only propagates through a medium of matter. In a vaccuum there is not heat transfer. Hot things do radiate energy, they create light. So if you were generating lots of waste heat the only way to get rid of it would be to become a bright light.

Well space do transfer heat but very very slowly and in the form of EM radiation (that in itself might be totally invisible).
So no, people dont instant freeze if exposed to space like we see in movies, actually people or rather parts of them, boil but that is for another discussion..

Especially because we have, fairly recently, created lasers. The setting of 40k has an additional THIRTY-EIGHT THOUSAND YEARS to make them better. Think about that for a moment. Thirty-eight thousand years. That is more than four times the entire length of human civilization from its very beginnings to the modern era. We went from baking mud bricks in the sun and carving cuneiform characters on stone tablets to digital, globe-spanning communications and space exploration in only ten thousand years. Give ourselves four times that span? We're going to have some pretty nifty shiznit.

Sorry to spoil your fun but the laws of physics do not change. A laser is still a laser and will still be crappy in practical battlefield use on infantry level.

As for armour and mud well, it is highly situational. Lets say it starts to pour rain, all of a sudden the advancing infantry are shining and reflective.
Just put a reflective layer on top of your flak armour and you get the best of both worlds for practically no drawback.
If it is not practical then stuff heat absorbing ceramics into the flak and that´ll take care of laser radiation.

Excepting the fact that lasguns in 40K have both a thermal *and* a kinetic force. That mylar covering on your armor doesn't bounce the laser, it just melts as you get whacked with the white-hot baseball bat of force in the chest/shoulder/arm/leg/head/wherever you caught a round. It's not a "beam" of light, more like a bar or a bolt. It's more Star Wars blaster than Star Trek phaser... and does, also, somehow, create recoil, at least according to certain fluff.

Yes yes, twisting the laws of physics to fit your very own view and anything can be made to work.
do explain to us how it is that lasers in that future of yours are actually so slow that they are described as visible las bolts going back and forth like some starwars blaster.
I also love the "somehow" in your theory, guess you´ll use magic to explain that as well.

Lasguns are measured in an energy unit referred to as a "megathule" (18 of them, if I remember my Uplifting Primer). What, exactly, a megathule is, though, is not provided. It is commonly believed, in threads like these, to mean a "mega-joule", but there's nothing to support that other than the fact that they sound the same.

Think it said 17 or something. I also thought about this and if this indeed means mega joule then we have a problem. I would want to be anywhere near a rifle with a power pack containing that much energy, it´ll be like walking around with several bottles of high pressure gasoline strapped to your web on a battle field but I take it future lasgun packs are the absolute epitome of human technology if they can store these kind of energy levels as well as have the means of transferring it extremely fast and still be harmless if destroyed.

It also creates another problem in unreal capacitor technology but I guess they must have solved that one in the future.


I´m just glad that we are not discussing the technology and physics behind melta weapons

Sorry to spoil your fun but the laws of physics do not change. A laser is still a laser and will still be crappy in practical battlefield use on infantry level.

The laws of physics *do* change when the setting is science fiction and not functioning by any "real science" applicable in reality.

As I said previously, the Ruinous Powers say feth your physics, while they invert gravity and turn thoughts into individually sentient, malevolent beings.

Even outside of this, in 38,000 years of development, humanity may develop the metallurgy and power requirements to have a man-portable direct energy weapon that is capable of providing sustained kineto-thermal output that is lethal to a broad variety of humanoid (and otherwise) targets.

It would be the height of ignorant arrogance to pretend we know all there is to know about physics at this point in M3.

Yes yes, twisting the laws of physics to fit your very own view and anything can be made to work.
do explain to us how it is that lasers in that future of yours are actually so slow that they are described as visible las bolts going back and forth like some starwars blaster.
I also love the "somehow" in your theory, guess you´ll use magic to explain that as well.

Because that's how the books describe them as functioning. Don't like it? Take it up with Games Workshop.

I don't need to explain to you how it's done, because it's a standard in the setting that that is the manner in which they work. The "how" behind it is, frankly, irrelevant.

This isn't a discussion of making the Imperial Lasgun work IRL, but an examination of how they work in the setting.

Think it said 17 or something. I also thought about this and if this indeed means mega joule then we have a problem. I would want to be anywhere near a rifle with a power pack containing that much energy, it´ll be like walking around with several bottles of high pressure gasoline strapped to your web on a battle field but I take it future lasgun packs are the absolute epitome of human technology if they can store these kind of energy levels as well as have the means of transferring it extremely fast and still be harmless if destroyed.

The Imperium's science is just that tight.

How they did it, we'll never know. We do see, though, that they managed to do it.

I´m just glad that we are not discussing the technology and physics behind melta weapons

It's described as an energized beam of ionized particles that cause the targets to undergo rapid nuclear fusion.

 Psienesis wrote:

It's described as an energized beam of ionized particles that cause the targets to undergo rapid nuclear fusion.

Oh gak.

For the record, the reason why someone might boil in space is because boiling and freezing points (the temperature at which a material melts/solidifies, or boils/condenses), especially of materials that are liquid in room temperature, are effected by pressure. In space, there is no pressure.

This is why water boils at a lower temperature at the tops of mountains; similarly, this is how pressure cookers work, by letting water reach a higher temperature before boiling through high pressure. And of course, sublimation-- solid to gas-- requires a similar pressure/temperature trick.

Regardless, lasguns and flak armor are amazingly advanced weaponry compared to our timeframe. So meh.

 Pyriel- wrote:

In space though, there is no where to dump your heat. Heat only propagates through a medium of matter. In a vaccuum there is not heat transfer. Hot things do radiate energy, they create light. So if you were generating lots of waste heat the only way to get rid of it would be to become a bright light.

Well space do transfer heat but very very slowly and in the form of EM radiation (that in itself might be totally invisible).
So no, people dont instant freeze if exposed to space like we see in movies, actually people or rather parts of them, boil but that is for another discussion..

For me EM radiation is light, although not all is visible light.

The sun emits massive amounts of heat in the form of EM radiation. This is, obviously, a much more massive amount of radiation than the human body would produce. But it's still an example of heat being given off by an object in space.

Might as well dump this out from the 6th edition rulebook, since it is (to my knowledge) the most detailed depiction of how lasweapons work (moreso than 3rd anyhow) outside of non-GW materials (and I don't want ot bring those in because things will degenerate into arguing over whose sources are better. This discussion doesn't need more complication.

6th ed. rulebook wrote:lasweapons do not fire a projectile or slug, but instead project a brief, high-energy pulse.This beam can range greatly in strength, depending on the size of the las-weapon and the rating of its power source.
...
A las-pulse will shear through flesh producing a cauterised hole surrounded by blister-burns. when first striking flesh, a las-pulse will cause a flash-burn effect upon impact, as the heat of the discharge causes the immediate surface area of the target to be vaporised. This can, to the untrained eye, take on the same wound aspects as those produced by high density explosives, but there are major differences when it cornes to field dressing las-wounds. While the brief exploding flash of initial contact is hlghly visible, it is rarely the major concern of aid givers. It is typically the continuing projection of the las-beam boring into the body that causes the most extensive damage - the beam will puncture through any internal organs and is capable of severing limbs.

And discussion of treatment:

6th edition rulebook wrote:Do not treat until you have ensured the victim is removed from the source. Las-weapons produce a narrow amplified beam of light. Most often this is a short burst, however, should the shaft be ongoing and still present, it is dangerous to approach.
..
Identify the impact site and determine the extent of the flash burn. Lift away any clothing covering the burnt area, without pulling material over the burns. Leave in place any material that has been seared into the burn area. If the victim is wearing arrnour, be aware that some materials absorb heat, leaving the area dangerous to touch. In a hazardous environment (such as chem-zones, radsites, or other such dangerous areas) do not cut away any protective covering - apply the dressing directly over it.
...
Find the penetration level of the beam. Has the beam passed through the victim causing an exit wound? It is best to check as soon as possible. The extreme heat cauterizes the wound, leaving minimum bleeding, however, rapid swelling will begin around the area almost immediately, making later diagnosis more difficult. If the las-wound is only a glancing hit, in a limb, or shows no signs of striking a vital organ, proceed with Field Dressing Type I. If you suspect the las-wound has penetrated a vital organ, go straight to Type II.

This doesn't seem to be describing a continuous (wave) laser (EG heat ray) but more a pulsed laser of vaguely defined parameters (number of pulses, pulse energy, etc.) But there is nothing, to my knowledge, expressly wrong with the description.


This would be the only other obvious 'example' of lasguns in action (at least a quantifiable one that wasn't from novels) which was from the old Rogue Trader Compendium:

As the stones pattered to the ground, a Deathlight flashed the stunted bushes itno flame. Tarok sprang up and fired at the Brannath who had just given away his position. The man fell forward out of the bushes with a fist-wide, smoking hole punched through his body from front to back. Strange, thought Tarok, that there is no blood.

That thought almost cost him his life. He almost failed to notice the shadow sliding over the rocks behind and right of him. The rock glowed and began to melt as he dived away from the beam of the Deathlight. The Brannath was not quick enough with his second shot.

Then, on all sides of him, the air was shot through with the deadly bright rods of soldier-lightning.

...

They were watching through their magic, he knew - the same magic that made the Deathlight spit its soldier-lightning.

Whilst it doesn't explicitly say its a lasgun, I think its safe to say that its in the Imperial Army listing so its probably referring to Imperial Army lasguns. (the old ones without the stocks and with ranges worse than modern ARs by the Rogue Trader explanation provided for the in-game distances.) Do note as well that it did imply lasweapons were thermal weapons (at least enough with sustained fire to melt the rock, although the specifics are unsurprisingly vague.) rather than pulverizing it.

 Psienesis wrote:

Sorry to spoil your fun but the laws of physics do not change. A laser is still a laser and will still be crappy in practical battlefield use on infantry level.

Even outside of this, in 38,000 years of development, humanity may develop the metallurgy and power requirements to have a man-portable direct energy weapon that is capable of providing sustained kineto-thermal output that is lethal to a broad variety of humanoid (and otherwise) targets.

It would be the height of ignorant arrogance to pretend we know all there is to know about physics at this point in M3.

In the 41st millenium there are still men and one would assume that they are still just as vulnerable to projectile weapons as they are now. One would also assume they are still just heat based weapons as they are now.

The amount of energy that seems to be required to vaporize a few kilogram of flesh on a man seems to be 1,000,000 joules. Compare this to the energy in a fairly large rifle at 2,000 joules. Maybe that doesnt seem that large, only a factor of 500 but the energy of a car moving at 60mph is only 500,000 joules, so each lasgun shot is essentially twice as powerful as launching a 1500kg projectile at 60mph at someone. Yet it only vaporizes a small amount of flesh.
It seems to me if technology got better and you could harness and carry that amount of energy, you would still want to use projectiles, really big, really fast projectiles.


Additions to physics are undoubtably going to be made in the next 38,000 years yet they will be additions. It is unlikely you will be able to throw out the first law of thermodynamics. If you could, there wouldnt be much reason to have an empire or to value resources and no one want ever want for material.

Again that assumes your laser weapon is only a CW/heat ray type. Pulsed lasers can and do exist, and it seems to be possible to cause them to generate small explosions and 'drill' the target if you utilise the right parameters. Relying on mechanical damage effects drastically reduces the energy requirements to inflict injury. As I said people have proposed examples of this and posted how it would work. Which is, to my knowledge the closest we get to actual 'research' on laser weapons unless you want ot extrapolate from medical lasers and such (which is sort of relevant but not quite.)

Some sources depict them as CW/heat ray types but others seem to go with a pulsed laser.

Edit: Also I get queasy when people start doing 'comparisons' like to cars and stuff because physical collisons and projectiles are alot more complex than just the energy involved (momentum and all that.) I've had some nightmare discussions where people claim lasguns can penetrate tanks simply because the megawatt/joule lasgun calcs are equated to tank guns. :(

 Melissia wrote:
The sun emits massive amounts of heat in the form of EM radiation. This is, obviously, a much more massive amount of radiation than the human body would produce. But it's still an example of heat being given off by an object in space.

clearly we are all in agreement that energy is being transferred from the sun to earth, and many other places, by EM radiation or light. What is not happening is the matter in the sun, being hot, warming the matter on earth through convection.

The heat from guns, engines, people, most things we think of is transferred to surrounding matter and thus those things are cooled by convection. Hot things on earth do radiate, firing a machine gun for several minutes or running an engine without coolant and the metal will turn bright as it radiates energy, but most of the energy is converted by air/other matter.

A space ship has no matter around it, it is in a vaccuum. The only way it can lose heat is to radiate it away, making cooling more difficult.


Automatically Appended Next Post:

Connor MacLeod wrote:


Edit: Also I get queasy when people start doing 'comparisons' like to cars and stuff because physical collisons and projectiles are alot more complex than just the energy involved (momentum and all that.) I've had some nightmare discussions where people claim lasguns can penetrate tanks simply because the megawatt/joule lasgun calcs are equated to tank guns. :(

Sure the type of projectile, mass, and speed all make a big difference. The M1A1 kinetic energy penetrators have a muzzle energy of 20,000,000 joules. It still makes a huge difference whether they are made out of pressed tungsten(ductile) or depleted uranium(brittle)

 Selym wrote:

It could also be that lasguns have a small fragment of warp energy, that just needs to be unlocked with a continuous charge from a battery.
If that is the case, this would explain why lasguns are capable of even existing, having visible bolts, and only requiring some sun-charged battery power to run.

Connor MacLeod wrote:
Again that assumes your laser weapon is only a CW/heat ray type. Pulsed lasers can and do exist, and it seems to be possible to cause them to generate small explosions and 'drill' the target if you utilise the right parameters. Relying on mechanical damage effects drastically reduces the energy requirements to inflict injury. As I said people have proposed examples of this and posted how it would work. Which is, to my knowledge the closest we get to actual 'research' on laser weapons unless you want ot extrapolate from medical lasers and such (which is sort of relevant but not quite.)

All that pulsing the laser does is allow you to do the same damage by shooting with a less weaker laser as you could with a stronger laser. Right now getting a laser of sufficient power is extremely difficult. In 38,000 years I imagine that getting one powerful enough wouldnt be an issue. The energy requirement is going to be the same whether you are using 5 smaller pulses or 1 strong blast.


Automatically Appended Next Post:

 Selym wrote:

 Selym wrote:

It could also be that lasguns have a small fragment of warp energy, that just needs to be unlocked with a continuous charge from a battery.
If that is the case, this would explain why lasguns are capable of even existing, having visible bolts, and only requiring some sun-charged battery power to run.

so lasguns are concentrated Chaos gods. I guess we know why the Sisters of Battle don't use them.

 Exergy wrote:

A space ship has no matter around it, it is in a vaccuum. The only way it can lose heat is to radiate it away, making cooling more difficult.

Or by dumping hot material, e.g. sacrificial coolant fluid.

 Exergy wrote:

All that pulsing the laser does is allow you to do the same damage by shooting with a less weaker laser as you could with a stronger laser. Right now getting a laser of sufficient power is extremely difficult. In 38,000 years I imagine that getting one powerful enough wouldnt be an issue. The energy requirement is going to be the same whether you are using 5 smaller pulses or 1 strong blast.

Why do you say that? Timeframe has a huge impact on the effect in the context of what I am talking about because I'm mentioning explosive effects. We're literally talking the difference between TNT and gunpowder here. Deliver enough energy in a small enough volume in a fast enough timeframe, and you can make an explosion that can punch a crater in the target. Repeat it as many times as needed to make the hole you want through the target. This is impossible with current technology AFAIK (and certainly not in a man portable package like the lasgun) but it is not implausible either, because what I described is basically how chemical and nuclear explosions work.

Also: Do not assume this is a 'I'm right you're wrong' type of post. What you said re: lasers that operate mostly or purely by thermal effects is, as far as I know, more or less completely true (the sites I linked to even make similar arguments re: inefficiency of thermal laser vs bullet.) Its just a bit more complicated than 'lasers only burn through target and nothing else.' that's all. Especially since the method described is consistent with the aforementioned descriptions of lasweapons.

my old IG codex says they are armed with lasguns/autoguns.


there fore, both are equal.


in the 40k verse, las has better logistics, kinetic does more damage.
which makes me wonder why I can take auto cannons and heavy bolters in IG squads, but not multi lasers... surely the IG logistics would dictate more multi lasers if it was such an issue?

also, any battery will decrease in charge over time, where as catridages can be stored for 100's of years with little/no degredation.

I could see the focal mirrors and such being more delicate too.


personally i converted lots of my guard to have auto guns as well, mainly cause it looks cooler, and causes them to roll better!

god i wish I could still get the necromunda pattern auto gun on sprues....

 Flinty wrote:

 Exergy wrote:

A space ship has no matter around it, it is in a vaccuum. The only way it can lose heat is to radiate it away, making cooling more difficult.

Or by dumping hot material, e.g. sacrificial coolant fluid.

true!
reject a ton of heat into a reservoir with a refrigeration cycle and then dump the coolant.

Still you would then need to carry around a fair amount of coolant.

 easysauce wrote:

also, any battery will decrease in charge over time, where as catridages can be stored for 100's of years with little/no degredation.

Explosives degrade over time, while lasgun cells could easily be stored discharged and only charged when needed and issued to troops. Given they are supposed to have integrated charging circuits, they will self charge as long as they are being used so any short term storage losses will be topped up automatically.

Connor MacLeod wrote:

 Exergy wrote:

All that pulsing the laser does is allow you to do the same damage by shooting with a less weaker laser as you could with a stronger laser. Right now getting a laser of sufficient power is extremely difficult. In 38,000 years I imagine that getting one powerful enough wouldnt be an issue. The energy requirement is going to be the same whether you are using 5 smaller pulses or 1 strong blast.

Why do you say that? Timeframe has a huge impact on the effect in the context of what I am talking about because I'm mentioning explosive effects. We're literally talking the difference between TNT and gunpowder here. Deliver enough energy in a small enough volume in a fast enough timeframe, and you can make an explosion that can punch a crater in the target. Repeat it as many times as needed to make the hole you want through the target. This is impossible with current technology AFAIK (and certainly not in a man portable package like the lasgun) but it is not implausible either, because what I described is basically how chemical and nuclear explosions work.

Also: Do not assume this is a 'I'm right you're wrong' type of post. What you said re: lasers that operate mostly or purely by thermal effects is, as far as I know, more or less completely true (the sites I linked to even make similar arguments re: inefficiency of thermal laser vs bullet.) Its just a bit more complicated than 'lasers only burn through target and nothing else.' that's all. Especially since the method described is consistent with the aforementioned descriptions of lasweapons.

My understanding is you pulse the laser to keep the vaporizing material from getting in the way of the beam.

So if you have a laser of X strength you deliver it in a pulse of Y time that is sufficient to vaporize(explode if you will) a piece of material. You then wait some time between pulses to let the vapor get out of the way and then hit it again with another pulse of X strength over Y time to dig deeper.
Without the pause between the pulses the vaporization from the first pulse disrupts the light from the second pulse. So X strength over 2Y time does not work.

What I am saying is why not use a laser with 2X strength over Y time. Right now getting a laser of higher power is difficult, but one would assume that in 38,000 years they would have figured this out.

The energy required for 2X strength over Y time and X strength over 2Y time is the same.

Nothing about nuclear or chemical explosions involves pulsing. If you want more destruction it is also better to use the higher power setting rather than the lower power setting repeatedly.


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 Flinty wrote:

 easysauce wrote:

also, any battery will decrease in charge over time, where as catridages can be stored for 100's of years with little/no degredation.

Explosives degrade over time, while lasgun cells could easily be stored discharged and only charged when needed and issued to troops. Given they are supposed to have integrated charging circuits, they will self charge as long as they are being used so any short term storage losses will be topped up automatically.

Batteries degrade over time whether charged or uncharged.

I would however not venture to say in 38,000 years which would degrade faster. 40k chemical propellants or 40k chemical batteries. As there are relics in 40k that have been working since ~25k I would venture to say that the longevity of most things has gone way way up.

 Exergy wrote:

My understanding is you pulse the laser to keep the vaporizing material from getting in the way of the beam.

So if you have a laser of X strength you deliver it in a pulse of Y time that is sufficient to vaporize(explode if you will) a piece of material. You then wait some time between pulses to let the vapor get out of the way and then hit it again with another pulse of X strength over Y time to dig deeper.
Without the pause between the pulses the vaporization from the first pulse disrupts the light from the second pulse. So X strength over 2Y time does not work.

What I am saying is why not use a laser with 2X strength over Y time. Right now getting a laser of higher power is difficult, but one would assume that in 38,000 years they would have figured this out.

The energy required for 2X strength over Y time and X strength over 2Y time is the same.

Nothing about nuclear or chemical explosions involves pulsing. If you want more destruction it is also better to use the higher power setting rather than the lower power setting repeatedly.

Yes, you need a delay between pulses to let the vapor/plasma dissipate before the next pulse or it will absorb the energy of the next shot preventing further damage. But its more complicated than that. You have a total number of pulses in a 'shot', and you have a overall timeframe (to deliver all the pulses.) You also have a delay between pulses. Your 'equation' such as it is does not account for that. Moreover I have no clue what sort of assumptions regarding timeframe and how you're defining 'strength' simpyl saying 'energy' doesn't help much because its not addressing the damage mechanism.

In the case of the links I cited, you usually get tens or hundreds of pulses (although aspect ratio seems to dictate that smaller numbers of pulses are more likely to work than large numbers) delivered over a microsecond/nanosecond pulse duration (Depending on source) with something like a 1-10 microsecond delay between pulses (again depending on source). and all the pulses are delivered in a few milliseconds tops. What is described there does not even seem to remotely apply to your 'equation'. If you're assumign these 'pulses' are actually being delivered over multiple seconds... I'm confused why you would think that, since that's not what the sources I linked to even remotely describe. 'pulse' and 'shot' in that context are not even remotely the same thing.

Speaking of starships, I believe it is noted in the "Rocks Cost Money" article that the fuel of the various Imperial vessels is hydrogen peroxide (H2O2) or "dihydride dioxide" or some such spelled-out nomenclature.

Connor MacLeod wrote:

 Exergy wrote:

My understanding is you pulse the laser to keep the vaporizing material from getting in the way of the beam.

So if you have a laser of X strength you deliver it in a pulse of Y time that is sufficient to vaporize(explode if you will) a piece of material. You then wait some time between pulses to let the vapor get out of the way and then hit it again with another pulse of X strength over Y time to dig deeper.
Without the pause between the pulses the vaporization from the first pulse disrupts the light from the second pulse. So X strength over 2Y time does not work.

What I am saying is why not use a laser with 2X strength over Y time. Right now getting a laser of higher power is difficult, but one would assume that in 38,000 years they would have figured this out.

The energy required for 2X strength over Y time and X strength over 2Y time is the same.

Nothing about nuclear or chemical explosions involves pulsing. If you want more destruction it is also better to use the higher power setting rather than the lower power setting repeatedly.

Yes, you need a delay between pulses to let the vapor/plasma dissipate before the next pulse or it will absorb the energy of the next shot preventing further damage. But its more complicated than that. You have a total number of pulses in a 'shot', and you have a overall timeframe (to deliver all the pulses.) You also have a delay between pulses. Your 'equation' such as it is does not account for that. Moreover I have no clue what sort of assumptions regarding timeframe and how you're defining 'strength' simpyl saying 'energy' doesn't help much because its not addressing the damage mechanism.

In the case of the links I cited, you usually get tens or hundreds of pulses (although aspect ratio seems to dictate that smaller numbers of pulses are more likely to work than large numbers) delivered over a microsecond/nanosecond pulse duration (Depending on source) with something like a 1-10 microsecond delay between pulses (again depending on source). and all the pulses are delivered in a few milliseconds tops. What is described there does not even seem to remotely apply to your 'equation'. If you're assumign these 'pulses' are actually being delivered over multiple seconds... I'm confused why you would think that, since that's not what the sources I linked to even remotely describe. 'pulse' and 'shot' in that context are not even remotely the same thing.

I'm not thinking seconds, a total shot would need to be at least in miliseconds or things would. A nanosecond is a ludicrously small amount of time at which even light appears slow.

The amount of energy required to vaporize(you say explode) some material is still the same, regardless of what timescale you use.

If you want to boil a liter of water on the stove, it takes some amount of time based on how hot your burner is. If it is really really hot you can boil it all in a micro second. But pulsing the burner on and off is not going to boil the water faster and it certainly will not decrease the total amount of energy to boil the water.

I am will to consider a dirac laser that can switch on instantly, deliver an an immeasurably amount of energy to a target, and then turn off. They don't currently exist but one day they might. Say you have one that is capable of delivering 1,000,000 joules per nanosecond. I dont see how pulsing it into 10 bursts of 100,000 joules or 100 bursts of 10,000 joules with any wait time is going to vaporize any more material. Maybe you could drill deeper, but you still are not going to vaporize any additional material.

 Exergy wrote:

I'm not thinking seconds, a total shot would need to be at least in miliseconds or things would. A nanosecond is a ludicrously small amount of time at which even light appears slow.

So? lasers can operate on femtosecond scales (for medical use), so I don't think operating on nanosecond/microsecond timeframes is problematic. This is simply the duration in which the energy is delivered in order to simulate high explosive effects (again energy vaporizing matter in small area in very small period of time, to simulate explosion.

The amount of energy required to vaporize(you say explode) some material is still the same, regardless of what timescale you use.

Yes. But the difference is relying on other damage mechanisms than simply burning stuff.

If you want to boil a liter of water on the stove, it takes some amount of time based on how hot your burner is. If it is really really hot you can boil it all in a micro second. But pulsing the burner on and off is not going to boil the water faster and it certainly will not decrease the total amount of energy to boil the water.

But the point of the pulsing is not to boil huge quantitites of water in the pot in a short timeframe. Its to vaporize a very small portion of it very rapidly, so that it creates a fast, violent expansion of gases that we call an 'explosion'. A sufficiently violent enough explosion will do plenty of damage without being super-energetic. Again this isn't about primarily thermal damage mechanisms.

Connor MacLeod wrote:

 Exergy wrote:

I'm not thinking seconds, a total shot would need to be at least in miliseconds or things would. A nanosecond is a ludicrously small amount of time at which even light appears slow.

So? lasers can operate on femtosecond scales (for medical use), so I don't think operating on nanosecond/microsecond timeframes is problematic. This is simply the duration in which the energy is delivered in order to simulate high explosive effects (again energy vaporizing matter in small area in very small period of time, to simulate explosion.

The amount of energy required to vaporize(you say explode) some material is still the same, regardless of what timescale you use.

Yes. But the difference is relying on other damage mechanisms than simply burning stuff.

If you want to boil a liter of water on the stove, it takes some amount of time based on how hot your burner is. If it is really really hot you can boil it all in a micro second. But pulsing the burner on and off is not going to boil the water faster and it certainly will not decrease the total amount of energy to boil the water.

But the point of the pulsing is not to boil huge quantitites of water in the pot in a short timeframe. Its to vaporize a very small portion of it very rapidly, so that it creates a fast, violent expansion of gases that we call an 'explosion'. A sufficiently violent enough explosion will do plenty of damage without being super-energetic. Again this isn't about primarily thermal damage mechanisms.

I have never been arguing damage mechanism. The fluff says large hole due to vaporization, so I have been going from that.

A weapon that instead of vaporizing a large chunk instead just raises the body tempurature from 37 to 45 would incapacitate and likely kill any human. There have been a few people who have survived body temp above 45, but most die rather quickly.

The laws of physics *do* change when the setting is science fiction and not functioning by any "real science" applicable in reality.

No, then they are not laws of physics but laws of magic that you conveniently can bend and skew in order to fit your viewpoint.

Even outside of this, in 38,000 years of development, humanity may develop the metallurgy and power requirements to have a man-portable direct energy weapon that is capable of providing sustained kineto-thermal output that is lethal to a broad variety of humanoid (and otherwise) targets.

It would be the height of ignorant arrogance to pretend we know all there is to know about physics at this point in M3.

True but they would still have to follow basic laws of nature.
We can invent all we want in metallurgy etc but said inventions will still have to follow things like basic thermodynamics.

The point is either we talk about physics or this entire discussion is null and void since everyone can run of and excuse precisely whatever they want with warp and magic.
By the way, I did not know imperial tech like a lasgun and its power pack used warp sorcery to circumvent basic laws of nature.

Because that's how the books describe them as functioning. Don't like it? Take it up with Games Workshop.

I don't need to explain to you how it's done, because it's a standard in the setting that that is the manner in which they work. The "how" behind it is, frankly, irrelevant.

This isn't a discussion of making the Imperial Lasgun work IRL, but an examination of how they work in the setting.

By your own definition your argument is flawed.
The reason for that is that your so called settings are not singular. One settings lasguns are described as beams, another as visible bolts etc etc. We cant have a discussion based on "pick-your-version-of-the-magic" and thus all that remains is simple, singular laws of physics.

The question remains: Would a laser rifle or a kinetic rifle be better...nowhere does it say pick your setting or bring in warp sorcery.

The Imperium's science is just that tight.

How they did it, we'll never know. We do see, though, that they managed to do it.

lol
You really dont get what 17 megajoule means do you
And you talked about arrogance...

It's described as an energized beam of ionized particles that cause the targets to undergo rapid nuclear fusion.

...in what setting? lol
I guess there is another one where faulty ork "meltas" use ork collective psychic sorcerous thingies in order to make rusty crap work.
lol

For the record, the reason why someone might boil in space is because boiling and freezing points (the temperature at which a material melts/solidifies, or boils/condenses), especially of materials that are liquid in room temperature, are effected by pressure. In space, there is no pressure.

Shhh, dont spoil the fun. I was waiting for psiensis to barge in with some magical setting picked from just the right novel in order to excuse some weird sorcerous super technology abomination

For me EM radiation is light, although not all is visible light.

Ah, well we ought to clarify for future references then as it is an extremely broad spectra beyond "just" visible light.

Might as well dump this out from the 6th edition rulebook, since it is (to my knowledge) the most detailed depiction of how lasweapons work (moreso than 3rd anyhow) outside of non-GW materials (and I don't want ot bring those in because things will degenerate into arguing over whose sources are better. This discussion doesn't need more complication.

6th ed. rulebook wrote:
lasweapons do not fire a projectile or slug, but instead project a brief, high-energy pulse.This beam can range greatly in strength, depending on the size of the las-weapon and the rating of its power source.

lol
And there goes the slow starwars bolt theory
As said, it depends on what fluff you pick from, we have white lasers (eldar) the very same but black lasers (dark eldar) etc etc...

All that pulsing the laser does is allow you to do the same damage by shooting with a less weaker laser as you could with a stronger laser. Right now getting a laser of sufficient power is extremely difficult. In 38,000 years I imagine that getting one powerful enough wouldnt be an issue. The energy requirement is going to be the same whether you are using 5 smaller pulses or 1 strong blast.

The secret would mostly lie in the future capacitors.

in the 40k verse, las has better logistics, kinetic does more damage.
which makes me wonder why I can take auto cannons and heavy bolters in IG squads, but not multi lasers... surely the IG logistics would dictate more multi lasers if it was such an issue?

Simple: Tech degrading. They can make lasguns with ease but not multi lasers. They can make space ships but not antigrav jetbikes, they can make advanced neuro linked power armour and psychic weaponry but not a freaking auto stabilizer allowing a simple WW1 tank to shoot on the move...

It´s all so incredibly ridiculous that it borders on the laughable.

Speaking of starships, I believe it is noted in the "Rocks Cost Money" article that the fuel of the various Imperial vessels is hydrogen peroxide (H2O2) or "dihydride dioxide" or some such spelled-out nomenclature.

Could I use your own argument to disprove you by saying that in one novel they are actually using He3 as fuel?
Or am I not allowed to pick and choose my own settings to bring in magical, warp, tech, sorcery, setting?

The point is either we talk about physics or this entire discussion is null and void since everyone can run of and excuse precisely whatever they want with warp and magic.
By the way, I did not know imperial tech like a lasgun and its power pack used warp sorcery to circumvent basic laws of nature.

Yep.

Apparently it does, because that's how it works in the setting.

So, yes, discussions such as these are, as I mentioned before, possibly ITT or the last time this came up, a matter of choosing what fluff you want to go with. There's no consensus within the published materials. We didn't need you to be a condescending donkey-cave to point that out.

You really dont get what 17 megajoule means do you

It's not provided, in-setting, as a "megajoule". In-setting, we are given "mega-thule". What's a mega-thule? We don't know. It's a fictional unit of measurement.

It *could* be a mega-joule translated into a similar word... but that is not established fact.

For all we know, a thule is five mega-joules, so we have a laspack providing just insane levels of juice. We'll never know until GW explains what a mega-thule is and provides a real-world equivalent.

By your own definition your argument is flawed.
The reason for that is that your so called settings are not singular. One settings lasguns are described as beams, another as visible bolts etc etc. We cant have a discussion based on "pick-your-version-of-the-magic" and thus all that remains is simple, singular laws of physics.

The question remains: Would a laser rifle or a kinetic rifle be better...nowhere does it say pick your setting or bring in warp sorcery.

That's how it works in 40K. None of the products line up perfectly. Products from two different sources (like GW and Black Library) aren't even *intended* to line up. If you're going to try to argue physics in a sci-fantasy setting, you've already lost, because the setting, by its very nature, is neither intended nor designed to depict a scientifically-accurate reality.

So, in Gaunt's Ghosts, for example, we have lasguns that fire short blasts of "energy" that can deflect off solid, non-reflective surfaces (like the dark-brown stone walls of Hinzerhaus), strike with thermal and kinetic force (like the one that cracks Rawne's carapace breastplate and knocks him on his ass), cause recoil in the rifle (like Larkin's hot-shot lasrifle) and otherwise behave like we would expect a solid-projectile weapon to behave... except they're lasguns.

Last but not least, the stats provided in multiple sources, whether that's the BRB, Inquisition, FFG's DH or Black Crusade, etc. provide what are basically identical stats between comparable las weapons and SP weapons. The variances that *do* exist between them are situational, indicating that neither is clearly better than the other.

However, having carried an assault rifle and 1300 rounds of ammunition, if I could reduce the weight and bulk of that ammo by half? Hell, yes, I'd take the lasgun. Especially if it meant I could reload the magazine by putting it in the sun. Makes resupply *much* easier. Even if the lasgun had only half the range of the autogun, I'd still take it.

I guess there is another one where faulty ork "meltas" use ork collective psychic sorcerous thingies in order to make rusty crap work.

If you think that's how Orky Tech works, then... can't help you. That's just idiocy.

Ork Tech works because Ork Meks are competent mechanics. They're designed to be. Have been for 60+ million years. They just don't follow standard human design protocols, which is not surprising, considering that the Ork race is older than Humanity many, many times over.

The Adeptus Mechanicus is extremely humano-centric. It views the past technological developments of Humanity as the greatest things the galaxy has ever seen. Anything that doesn't match their preconceived notions of what is "viable technology" is, by its nature, incapable of functioning, and therefore *must* use Xeno sorcery to function.

It works because the AdMech doesn't understand Orkoid technology, not because the Orks simply believe it to work.

Shhh, dont spoil the fun. I was waiting for psiensis to barge in with some magical setting picked from just the right novel in order to excuse some weird sorcerous super technology abomination

Might want to pull your head out of your fourth point of contact, I wasn't involved in the discussion of what happens in space until we started talking about liquid coolants.

Me wrote:Speaking of starships, I believe it is noted in the "Rocks Cost Money" article that the fuel of the various Imperial vessels is hydrogen peroxide (H2O2) or "dihydride dioxide" or some such spelled-out nomenclature.

Could I use your own argument to disprove you by saying that in one novel they are actually using He3 as fuel?

Or am I not allowed to pick and choose my own settings to bring in magical, warp, tech, sorcery, setting?

Not at all, you're perfectly fine in pointing that out, because that indicates that none of the sources of this information we have available line up.

This is very much a "pick whichever option you like, you can't be wrong" scenario. Which is all I have been saying this entire time. Absolutely nothing in the information provided to us pertaining to the setting of 40K, specifically between las-weapons and SP weapons, indicates that one is clearly better than the other.

The DM goes with lasguns because of logistics. Makes sense from the standpoint of an organization of bean-counters that have to supply trillions of soldiers across the galaxy. The US military works on much the same principle. Effectiveness is balanced against cost and practicality. It is one of the many reasons why we don't plate every HMMWV in ceramic armorplate.

In hall that you guys are comin up with such great response's to this . Generally I think both have their distinctive advantages and disadvantages to each other but I am certainly impressed with all of the points people are bringing forth , and most Importantly thanks for being civil

 Exergy wrote:
I have never been arguing damage mechanism. The fluff says large hole due to vaporization, so I have been going from that.

Okay I think I see what is going on here. Let me quote the two bits *I* remember as to what lasguns do. I already posted 6th, but this is what third edition says and I think thats what you're going off of:

This is what third edition said about lasweapons

Cheap to manufacture and easy to use and maintain las weapons are issued in vast numbers to the Imperial Guard and are readily available on most Imperial worlds. Laser weapons emit a beam of focused light. The short duration high energy beam produces such a rapid temperature change on the target's surface that it vapourises in a small explosion. Lasguns are driven by a fast discharge generator, which comprises most of the lasgun's mechansim and stores energy for each shot.

Note it describes a rapid temperature change, on the surface, that it vapourises in a small explosion. You could describe that as 'vaporising a hole in the target', but you can just as easily say 'its vaporizing the surface to create explosive damage', since its not explicitly saying 'it vaporizes a hole through the target creating an explosion'. Heck it doesn't even specify how big an area is vaporized (which can still justify the type of pulse laser I describe.)

Further context can help, as per 2nd edition Wargear:

The laspistol or laser blaster is a pistol version of the lasgun and enjoys the same reputation for ease of manufacture and convenience of use. It is a standard weapon amongst the Imperial Guard, and one of the most common of all weapons carried by the Adeptus of Earth. It fires distinct bursts of laser energy, or laser shells, which explode when they hit their targets. Because the laser's energy is rapidly dispersed into the atmosphere shots at long range tend to be much less accurate than short range fire.

Laspistols fire energy bursts that explode on impact. We could figure that means explosive shells of course (and they aren't really lasers) or it means something akin to what is described in 2nd edition - it makes the surface vaporize explosively and blasts a crater in the target.


2nd edition Wargear again:

The lasgun or laser gun is the standard weapon of the Imperial Guard and the most popular weapon amongst most human forces. It fires an explosive energy blast with a similar effect to a bullet or small shell.

Again 'explosive' energy blast, and it has an effect akin to a projectile weapon of some kind or another (which suggests again, drilling a hole through the target, and not neccesarily a large one) The pulse lasers I have described can in fact do this, but its very hard to describe a energy weapon that could closely simulate a projectile impact (and vaporizing large portions of the target is probably going to produce something more akin to a grenade unless its over a large volume or a very large fraction of a second and thus would probably do more widespread burning than hole punching.)

Now we could continue arguing over interpretation, but I don't really see any reason to. I've believed that it meant what you do (EG lasweapons must vaporize holes through targets!) but that honestly is not the only inteprretation. I'm not saying you CAN'T interpret it that way, of course, and if you want to believe that's how it works you're free too. I'm just pointing out it does not neccesarily need to work that way and could work just as well or better other ways.

I actually like the 'pulsed lasers' because they have ludicrous penetration (vastly better than modern AP rounds.) When you consider storm bolter rounds have been described as penetrating eight inches of plasteel in Epic, and BattleZone Cityfight describes laspistols punching lasbolts through brick walls to injure targets on the other side.. well.. lasweapons seem pretty damn impressive that way. Although again even with pulsed lasers the performance can be varied depending on what you go for, so it doesn't automatically mean lasguns have awesometastic penetration either

Another advantage is that a pulse laser as the links I mentioned describe is also easier to reconcile with the ability to recharge lasguns by solar power (in presumbably reasonable timeframes), cooling and ineffifiencies (EG not melting the lasgun or its intenral components) and even battery size. Which means that you get less people arguing you're trying to spank out lasweapons (saves you migraines there, in my experience.)

A weapon that instead of vaporizing a large chunk instead just raises the body tempurature from 37 to 45 would incapacitate and likely kill any human. There have been a few people who have survived body temp above 45, but most die rather quickly.

So I have heard, but how quickly does it incapacitate or kill that way? Even if you heat the torso to that it probably is going ot take what, a megajoule? You could probably use severe flash burns (3rd-4th degree, as in nuclear explosions) to be nearly as lethal with far less energy (really severe flash burns will actually cause steam explosions in the tissues, as I recall. I'll have to dig into the Nuclear Weapons FAQ)

But I'm going to note anyhow that a weapon that raises body temp is not a weapon that is punching large, lethal holes through people or blasting off limbs.