It Takes 2.99 Gigajoules To Vaporize a Human Body 272
Have you ever wondered how much energy is needed to power a phaser set to kill? A trio of researchers at the University of Leicester did, so they ran some tests and found out it would take roughly 2.99 GJ to vaporize an average-sized adult human body. Quoting:
"First, consider the true vaporization – the complete separation of all atoms within a molecule – of water. With a simple molecular structure containing an oxygen atom bonded to two hydrogen atoms, it takes serious energy to break these bonds. In fact, it takes 460 kilojoules of energy to break just one mole of oxygen-hydrogen bonds — around the same energy that a 2,000-pound car going 70 miles per hour on the highway has in potential. And that's just 18 grams of water! So as you can see, it would take a gargantuan amount of energy to separate all the atoms in even a small glass of water — especially if that glass of water is your analog for a person. The human body is a bit more complicated than a glass of water, but it still vaporizes like one. And thanks to our spies spread across scientific organizations, we now have the energy required to turn a human into an atomic soup, to break all the atomic bonds in a body. According to the captured study, it takes around three gigajoules of death-ray to entirely vaporize a person — enough to completely melt 5,000 pounds of steel or simulate a lightning bolt."
well done (Score:2, Funny)
Just in time now that Texas can't get Sodium Thiopental.
Re:well done (Score:5, Informative)
Leicester is correctly pronounced "lay-ses-ter".
No it isn't. It's pronounced "les-ter".
Source: I've been there. Also, this [wikipedia.org].
3 GJ to vaporize? (Score:3, Interesting)
Well, another way to look at this is that the human body contains 3 GJ of constrained energy, and that if you released that energy -- like an atom bomb -- rather than trying to match energy for energy, you'd *get* 3 GJ, which you would then have to put somewhere, or you'd be vaporized along with it.
Remember: A good sized atom or fusion bomb contains (and will release) more than 3GJ of energy, but it takes one hell of a lot less than 3 GJ as a trigger to let that energy free.
And given that there are at least
Hmm (Score:5, Funny)
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It's gonna take a mighty big shark to carry around that kind of firepower . . .
Don't give the Sci-Fi -- I mean SyFy (sigh) -- channel any ideas. Sharknado [wikipedia.org] was bad enough.
Re:Hmm (Score:5, Funny)
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Topshark - 80's movie, about the American pilots who went up against those Russian Sharks.
Re:Hmm (Score:5, Funny)
SyFy (sigh)
Iy think you myght have meant (sy).
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It's gonna take a mighty big shark to carry around that kind of firepower . . .
Don't give the Sci-Fi -- I mean SyFy (sigh) -- channel any ideas. Sharknado [wikipedia.org] was bad enough.
Here's another terrible idea: Antalanche >.>
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Terrible ideas at the refresh of a page: TRHOnline.com - SyFy/Sci Fi Channel Original Movie Generator [trhonline.com]
Ma
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You must not have actually seen Sharknado before criticizing it - honestly, it was pure, ridiculous, unapologetically B movie genius.
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Dr. Emmett Brown: No, no, no, no, no, this sucker's electrical, but I need a nuclear reaction to generate the 1.21 gigawatts of electricity I need.
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Nonsense. 2.99GJ is simply 1.21GW over 2.47 seconds.
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"Nonsense. 2.99GJ is simply 1.21GW over 2.47 seconds."
But it's all irrelevant, because OP's main premise is obviously false.
If we want to take the situation even a little bit literally, then a phaser could not be "vaporizing" its target. If it did, there would be a tremendous explosion. In fact, 2.99 GJ worth of "boom".
But we don't see that. Therefore a phaser could not be a "vaporizer" at all. Nor could it be a "molecular dissociation" device because the result could be the same.
I would have to theorize that it was some kind of device to send matter
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Disintegration (Score:5, Interesting)
Phasers don't vaporise a person. They disintegrate them.
Since we don't yet know the physics behind this phenomenon we can't say how much energy it needs.
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- memory-alpha.org
Though I suspect the Star Trek phaser suffered from the same problems as the StarGate zat'n'ktel, in that the effect would be a wee bit too convenient for plot reasons - as I've rarely seen them use i
Re:Disintegration (Score:5, Insightful)
Often on TV, killing is actually easier than dealing with the bodies. The network censors really hate bloody corpses, but have less objection to the process of making them. A common solution is to introduce either mooks that conveniently diappear when dead (See Buffy, Charmed - the prefered fantasy solution) or weapons which leave no body (See half the weapons in Doctor Who or STs phasors - the prefered sci-fi solution).
The vaporisation option usually ignores the difficulty of where approximately eighty kilograms of water vapor is going to end up - boiling a human in such a short time would result in a blast of high-pressure superheated steam and organic soup.
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Often on TV, killing is actually easier than dealing with the bodies. The network censors really hate bloody corpses, but have less objection to the process of making them. A common solution is to introduce either mooks that conveniently diappear when dead...
Saves money, Saves time.
You don't have to show the blood and bodies on screen. You don't have to remove the blood and bodies on screen.
The same reasons why Star Trek and Dr. Who have teleportation. Why the TARDIS is bigger on the inside than the outside.
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I always figured that phasers had some sort of reclamation tech -- where the energy deployed in the first phase was then reclaimed, thus solving the issue of a bunch of superheated water vapor -- leaving it instead as ambient temperature water vapor, and the phaser as reusable. That was my own way of reasoning it away all those years ago, anyway.
I could never figure out how you could set a phaser to "stun" though -- does it just change the phase of some molecules while ignoring the bulk of them?
I figured it used transporter/replicator technology and this is where all the food in the galley came from...
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Sorry, I used poor phrasing :)
What I meant was - I rarely saw the Star Trek phaser used in a 'disintegrate' setting when used on living things, even though it would have been rather useful (no body to discover, e.g.)
The zat was of course used pretty much every other episode. Which is a shame - I'm partial to the staff weapon ;)
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Staff weapons are weapons of terror, not combat. I'd quote the episode, but I'm lazy. It was one of the ones were they were just starting to partner with the Jaffa, and they had O'neall talking about the MP5s they use, the staff weapon fired at a log hanging took some hits and missed, the MP5 in Sam's hands, cut the swinging target in half.
Yeah the Jaffa 'marksman' demonstrating the staff weapon took about 3 shots just to hit the swinging log and all the Jaffa cheered at his amazing prowess.
Sam cut the rope with the MP5 on full auto almost instantly and the Jaffa kind of went quiet and sheepish.
IIRC it was the episode where the Goa'uld Imhotep was posing as a Jaffa leader.
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Reintegration (Score:4, Funny)
They're called "Phasers". I like to think that they don't disintegration or vaporize people, they just phase them into another dimension, a dimension where all the other folks who got zapped are hanging out, bitching about the Federation in some kind of distributed cosmic basement...
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No, you're thinking of the Positronic Ray.
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What do disrupters do then?
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Disrupt molecular bonds, I guess.
While phasers phase molecular bonds.
In some theoretical sci-fi future, there is a difference.
Perhaps the reason they are hand-held is they actually produce the energy needed as part of their discombobulation process by capturing the existing energy of the molecular bonds and redirecting it, sort of like a nuclear chain reaction. So it only needs a little zap of energy to kickstart the process.
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Because most molecules in the human body are simply too big: the energy needed to separate them from each other is greater than the energy needed to break them apart. You can observe this behavior if you have a fireplace: a log of wood will first burn with a flame as volatiles evaporate and mix with
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Most of the molecules in the body are not too big, as most of the body's molecules are water molecules. That is why the researchers used water as the body analogue. But when you talk about vaporizing water, you are just talking about turning it into water vapor, not separating it into its atomic parts. So to really get an accurate energy estimate for a phaser set to disintegrate, you need to calculate the energy required to turn the water fraction of the body into water vapor, plus the energy required to br
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I think the most logical way a phaser on disintegrate setting could work would be some effect that neutralizes the strong nuclear force. [wikipedia.org] Then whatever you hit with it would just disintegrate to a cloud of quarks.
Vaporize or ionize? (Score:5, Informative)
Hang on a moment... TFA isn't talking about vaporizing - turning water to steam. It's talking about ionizing, which is clearly going to require a much bigger quantity of energy.
For actual vaporization, making a very rough calculation - 60kg person, 2,270 kJ/kg latent heat of vaporization of water = 136 MJ,
Sure there's specific heat to add in there too, but the vaporization of water is the dominant term, so it's at least out by an order of magnitude.
Lesson learned - don't try and be 'all sciency' and use the wrong jargon!
Re:Vaporize or ionize? (Score:5, Insightful)
the complete separation of all atoms within a molecule
And then what? You have <however> many moles of highly reactive ions in a location. What are they going to do? React again. So all you've done is apply energy to a mass, liberated a bunch of ions that will then recombine as soon as the input power goes away (or they dissipate from out of its field) and then release the energy of ionisation that they had absorbed. Result: Boom! All that 3GJ comes back at you as a chemical explosion.
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Vaporization is not the same as hydrolysis. Vaporisation means liquid turning to vapor.
Bad science (Score:5, Interesting)
Re:Bad science (Score:4, Insightful)
Even so when you go from a liquid to a gas let alone a solid to a gas you increase volume by well allot! Considering the epic calamity that is ~man sized boiler, say the type that was used to power to power stream tractors makes when it bursts; it should be clear that a phaser blast is not turning the victim into a gas or plasma. If it did that, it would be very disruptive and probably harmful to anyone in the immediate vicinity. Yet in Star Trek you can safely stand next to someone that is being disintegrated by phaser/disruptor.
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Only if you stand perfectly still while they're being shot, then don't react until just after they've disappeared ...
Re:Bad science (Score:5, Funny)
depends if you're wearing a red shirt or not
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One thing I've never understood: how do the phaser beam know when to stop vaporizing? I mean, if I'm sitting in a desk chair and get vaporized by a phaser, then the chair usually remains there, completely unharmed and pristine. How does that work? Is it just super-sensitive to boundaries of conductivity? Shouldn't my clothes be left behind, too?
Re:Bad science (Score:5, Funny)
Shouldn't my clothes be left behind, too?
That's "The Rapture," not a phaser. Different canon, so to speak.
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That's called a defabricator [youtube.com], and it's a whole lot more fun.
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I wouldn't say "safely"...
Depends on who's holding the phaser, and if he's planning to aim it at you next.
Re:Bad science (Score:5, Interesting)
You need enough energy to turn them from a solid/colloid state to a gaseous state, not the energy required to reduce the person to elemental atoms.
I can't wait to see how much energy people say the transporter requires.
I assume it is a similar principle.... except the phaser set to disintegrate just has to scramble and disperse their molecules, so that the person or thing no longer exists in a recognizable form; the transporter has to reassemble people.
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> 2013
> Not vaporizing your water with electrolysis.
> Not enjoying the rich flavor of combustion brewed tea.
At least ditch that wet drip coffee and try Fuel-Air-Coffee -- It's the bomb.
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van der Waals forces are not the main factor that keeps water molecules together - it's hydrogen bridges and dipole-dipole interactions.
In fact, in a water molecule, van der Waals forces are tiny.
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Since when did a phaser VAPORIZE its target? (Score:3)
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The phasers you remember were obviously set to Stun.
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The phasers you remember were obviously set to Stun.
Even kill didn't do anything other than make the target drop dead.
That is what disruptors do.
At some point the Enterprise hand phasers got a Disrupt-B or Maximum setting besides overload, that makes the target glow, and vanish.
You have to remember that star trek is a TV show; and the disintegration was clearly for dramatic affect. They were essentially making the phaser like alien death rays that had appeared in other television shows.
The phas
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There's always room for another setting on a prop dial!
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Self Bootstrapping Death Ray (Score:5, Interesting)
Directly providing the power to vaporize a person is not the elegant way to do it. The correct, elegant mad scientist method is to use the power contained in the vaporized mass to power the vaporization.
Consider if you develop a means to "program" a plasma such that it generates a contracting magnetic field that causes fusion inside the vaporizing object and then absorbs some of the energy from this fusion reaction to power itself.
Now you're talking! Now you've got an effect that can vaporize any object provided you can provide the initial energy requirement.
There could be variants on this. Perhaps you've got an effect that flips matter into antimatter and absorbs some of the released energy to continue the effect.
If this is an expanding effect instead of a collapsing effect you've got a world killer like the weapons in Ender's Game.
useful info (Score:3)
*turns knob up to 8*
Ready Player One...
Potential? (Score:3)
around the same energy that a 2,000-pound car going 70 miles per hour on the highway has in potential.
Wouldn't that be kinetic?
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Could be an elevated highway...
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Perhaps it is both? Speed it all relative, you really only realise that energy if you apply the breaks of hit something. So it is really just potential energy.
Going really fast is like being really high, you have easily accessible potential energy.
Now, what would 3GJ of hyper heated matter... (Score:2)
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Actually, I can answer that question. It just happens that some friends and I like to dabble in high-voltage fun. We don't have a 3GJ test, but I do have a video showing what just 800J does to a tomato:
http://birds-are-nice.me/explodium/MK8a_fruit.webm [birds-are-nice.me]
Up-one to see more things go pop.
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Slo-mo cameras cost a fortune. I could only find one remotely affordable, but it can only do 240FPS at very low resolution.
Overkill (Score:3)
Nope, just boil water and burn most other matter (Score:2)
Doesn't take gigajoules, just what is commonly done in crematoriums, but done at much faster speed for cinematic effect. I am sure most people will not mind a small puddle of calcium-based ashes, but if they do we can focus on sublimating that and still save lots of juice. For even more savings, add corrosive acid that would produce residue with lower sublimation point.
Kickstater to raise 2.99GJ to vaproize Justin Bieb (Score:3)
Ashton Kutcher
Miley Cyrus
Kate Perry
Guy from Verizon Wireless commericals
Congress
Huh, whad'ya know... (Score:2)
On things I've never wondered about, this would be pretty much right at the top of the list...now how much energy is required on the 'stun' setting?
Must be Friday the 13th or something. :)
Transporter of the future? (Score:2)
So does this also give an indication of how much energy an transporter(Star Trek like) would consume(assuming 100% efficiency of course)?
I've always wondered how much energy would be needed for transportation like that. Always wanted to see if its more/less efficient than driving your SUV to work.
Awful calculation - the real answer is almost zero (Score:4, Informative)
I'm going to do some rough calculations - the paper's computation is also pretty rough - just to get the right order of magnitude.
First of all, to vaporize water, you don't even need to boil it. Spill some water on the floor and it vaporizes pretty darn quick just from the ambient environment - it changes from liquid water at room temperature to water vapor at room temperature. The only heat that needs to be added is the "Enthalpy of vaporization" which is 2260 kJ/Kg. For the 78kg human described in the paper, if it were all water, that would only be 176 Megajoules. Given that a human is normally at about 37C and room temperature about 25C, you can also take away 4kJ/Kg*78Kg*(37-25) = 4 Megajoules that the water vapor releases as you cool it from 37C to 25C. The net result is that with 172 Megajoules, you can turn a human body's mass of water to vapor.
However, as the paper suggests, the body isn't all water - it's about 85% water and 15% "dried pork." That means 172MJ*0.7 for the water, 146MJ, and the 11.7Kg of pork releases about 4KCal/g when oxidized (4 dietary Calories/g), 1 Kcal=4.2KJ, so burning the "dried pork" releases 196MJ. Assuming the "dried pork" gets fully oxidized (i.e burned) into CO2, the result is a gas. So overall, vaporizing a human body (in the sense of turning all the body into a gas) can release more energy than you started with - about 50MJ.
The paper estimates the energy required to break every molecular bond. However, all those bonds are going to reassemble into something else, whether into H2, O2, or H2O, or including the "dried pork," CO2, releasing much of the energy back.
Secret Nazi Weapon (Score:2)
190 Megajoules (Score:2)
Suspiciously accurate (Score:2)
It is ridiculous to use "roughly" and "2.99" in the same measurement. Seriously?!? A professor informed my engineering class that adding extra decimal places implied that that level of precision was known and/or required. It is at all plausible that the variability in the "average" human body is less than a one part per thousand?
Sounds a lot like Karl Marx when he took material costs in "round numbers", "assumed" costs for spindles and rates of waste, arbitrarily "put" wear and tear at 10% and "supposed" a
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what happens when you use that at 88MPH? (Score:2)
what happens when you use that at 88MPH?
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I'd imagine you get something that looks a bit like a pink comet.
shortcut (Score:2)
They don't know anything about phasers (Score:3)
Everybody knows that when set to kill the phaser emits high energy polarized tachyons that send most of the mass into other dimensions. From the PoV of the infinite other universes a harmless burst of neutrinos occurs at several random locations. The matter that doesn't get transferred by the tachyons may remain as a dusty residue, but that's only if the phase correlator is poorly adjusted. Properly maintained phasers set to kill won't do that.
And yes, I just made all that up, and some of it is mumbo-jumbo. That's how Star Trek technology works. Dammit Jim, I'm a Slashdot poster, not a phaser technician. Why do I have to explain this?
"out of phase" or subspace? (Score:2)
The only "reasonable" explanation within the Star Trek canon (if the term applies) is that the corpses are pushed "out of phase" or into subspace or something. Otherwise, there really is no place for the mass to go.
Just the Thing for Eugenics! (Score:2)
I know where we are heading with this.
So, in this case (Score:2)
By my calculation (Score:2)
That means a fully equipped DeLorean could vaporize you in 1.35 seconds of time travel.
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*2.47 seconds. I somehow remembered it as 2.21 gigawatts.
Roughly 2.99!!! (Score:2)
OK, OK. I get the message! (Score:2)
Re:JiggaWatts (Score:4, Insightful)
Depends on how quickly you want it done.
If you wanted it done in 2.5 seconds, 1.21 gigawatts would be perfect.
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I think that's about how long it took Captain Terrell to commit suicide between the length of the phaser firing and his body disintegrating.
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2.47 s (Score:2)
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While some folks choose to pronounce giga as jigga, it always makes me cringe and think less of them. Ugh.
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indeed, let's just consider the human body a bag of water. To raise 75 kg of water 70 degrees C requires 4 kilojoules per kg for each degree, so 21 MJ. But then to vaporize water at 100 degrees C is 2.3 MJ / kg or 172 MJ. So our answer is about 200 MJ. A gallon of gasoline is about 130 MJ, so the energy in about one and a half gallons would do the job. Or if your home pulls 12.4 KWhour a day in the summer that's 44 MJ, so less than 3 days worth of summer power
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As a practical matter you need well over that amount of energy if you don't want solid pieces laying around. How much energy does it take to vaporize bone?
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gee, and I was happy with my hypothetical death ray leaving a pile of cooked bones hitting the floor with a clatter. I can't think of any better way to move things forward in multi-species negotiating session with one asshole antennaed green man holding up the discussion.
Well, medical texts on laser ablation give the poop: 320 to 560 KJ / Kg heat of vaporization, after getting to 1600 degrees C with 1.3 KJ / Kg of heating. So 10 kg (22 lbs) of bones * 1.3 * 1600 = 21 MJ to get to point of vaporiz
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Our local utility is subsidizing the replacement of inefficient incandescent death rays with the more efficient LED ones.
They tried CFL death rays, but one was better off just getting the subject to break them and inhale the mercury.