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It Takes 2.99 Gigajoules To Vaporize a Human Body
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."
Just in time now that Texas can't get Sodium Thiopental.
It's gonna take a mighty big shark to carry around that kind of firepower . . .
I read TFA and all I got was this lousy cookie
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.
Since when does "vaporization" involve breaking chemical bonds inside a molecule? When you boil water you're not turning it into hydrogen and oxygen, you're just overcoming the vanderWaals bonds keeping the liquid together and giving them enough energy to float away. Likewise if you "vaporize" someone. 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.
Seven puppies were harmed during the making of this post.
The phasers I remember just made their target clutch their chest and fall to the ground dramatically.
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.
*turns knob up to 8*
Ready Player One...
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...
Depends on how quickly you want it done.
If you wanted it done in 2.5 seconds, 1.21 gigawatts would be perfect.
upon the advice of my lawyer, i have no sig at this time
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?
systemd is Roko's Basilisk.
Jiggawatts is just jiggagoules over time.
Scientists point out problems, engineers fix them
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Vaporization isn't needed to kill. I assume that's what death rays are all about. I suppose it would take a little extra to make the remains difficult to identify. If you've gone the death ray route, using lots of power is part of the "send a message" image thing anyway. For an eco-friendly kill, it is still best to club the victim and let hungry pigs dispose of the corpse.
If successful we can work our way down list with future kickstarters:
Ashton Kutcher
Miley Cyrus
Kate Perry
Guy from Verizon Wireless commericals
Congress
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.
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!
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?
For all intensive purposes, "whom" is no longer a word. That begs the question, "who cares"?
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 those two ways to approach bounded energy release, odds are reasonable that there are others, as well. Yes, yes, fissionables sort of *like* to be let free, but that's kind of the point. Perhaps there are other mechanisms.
And therefore, I'm just going to go with "Phasers don't have to deliver 3 GJ to vaporize a Klingon."
I've fallen off your lawn, and I can't get up.
Not roughly 3 GJ, but roughly 2.99!!!!! Clearly not written by anyone who understands engineering!
Unicorn Setu. "Eagles may soar, but weasels don't get sucked into jet engines".