Let’s say I’ve invented a sort of 1920s-style death ray that works by breaking molecular bonds (and leaving them broken).
I point it at a 70kg adult human male and it causes all of the atoms in his body to instantly dissociate into their elemental form (so the Carbon becomes monoatomic powder, the Hydrogen becomes H2 in a gaseous state, etc).
The properties of the beam are such that the components of the atomised residue are prevented from reacting with one another, at least for a little while (so the monoatomic Sodium metal powder does not burn when exposed to the elemental Oxygen)
None of the atoms themselves are split or fused - and any energy surplus or debt from the molecular bonds is balanced to zero by a mechanism too complex and boring for me to describe. The products are neither chilled nor heated by this transition.
The victim explodes, for sure, because all those things that are now gases will want to behave like gases, but the question is, how big of a boom?
What is the equivalent explosive yield of a human when I detonate him with my death ray?
Given your specification of no net energy released, I’d think that there would be no boom at all, with the individual atoms simply drifting away as if they suddenly forgot what they were hanging around for.
I don’t think it’s all just going to drift. For example, our 70kg person contains 2.25 kilos of nitrogen - that wants to be 2+ cubic metres of nitrogen gas, as soon as it’s dissociated.
Running the numbers through Wolfram Alpha, gives a volume of 109440 Liters for the big three (H, N, and O) at STP. So assuming at 70 Kg person takes up about 70 liters, that’s an expansion of 1560x.
I haven o idea how much of a “whoomph” that would actually get you. Since Hydrogen and Oxygen make up the biggest percent, really it would the sames as asking what would happen if you split water all at once.
The OP has already pointed to the nitrogen that suddenly becomes 2+ cubic meters of gas. The standard claim is that a human body is about 70% water, so right away you know you’ve got 49 kg of H2 and O, which breaks down as 5.4 kg (60 m[sup]3[/sup] of H2 and 43.6 kg (30.5 m[sup]3[/sup]) of O2.
So you’ve gone from a human body with a volume of about .07 cubic meters to a collection of (mostly) gas with a volume of about 2+60+30.5 = 92.5 cubic meters.
How big a boom? Depends on how fast the transformation takes place. If do it slowly enough (like filling a balloon), it could be silent. If you did it instantly, you could generate a severe/damaging supersonic shock wave in the surrounding atmosphere, which is pretty much what a bomb does.
We’re going for instantaneous release of all the molecular bonds - I’m not sure if that makes it hard or impossible to actually calculate - I guess in detonating explosives, there is still the constraint of the speed of the shock wave front within the explosive material - we don’t even have that here.
Maybe another way to look at it would be:
If you take the volume of a human, and subtract the volume of the solid elements, then compress the gaseous elements into the remaining volume, how high is the pressure?
A kilo of nitrogen takes up a lot of space because at room temperature the molecules are moving at an average speed of 500 m/s. What speed does your ray give them? Does it add the energy required to make them gaseous? Or leave them with the speed they had in the solid, and thereby lower the temperature to … whatever the temperature would be?
Good point - I’m going to fudge it and say that the magic that destroys the molecular bond results in products that are still at human body temperature.
Yeah, but if we are dissociating all molecular bonds, we don’t end up with molecules of H2, O2, N2, etc. We end up with atomic H, O, N, C, etc. I have no idea how pure atoms would behave in this situation, but I think they would be highly unstable, and lot of energy will be released as the atoms combine to form stable molecules.
A standard compressed-gas cylinder of nitrogen might be filled to a pressure of 136 atmospheres, at which point you’d expect a density of about 136 kg/m^3. The density of a human body is more like 1000 kg/m^3, so scale up the pressure accordingly - to 1000 atmospheres, or 14,700 psi. This is a pretty coarse estimate; I only found one phase diagram for nitrogen, and at these conditions it indicates that you’re into supercritical fluid territory, so the ideal gas law goes out the window.
Anyway, picture a pressure vessel with a volume of 0.07 cubic meters (18 gallons), filled to about 15,000 psi, and imagine how big a bang you’d get if it suddenly shattered. That’s what you’re proposing.
The monatomic N would, I expect, quickly recombine into diatomic N2. You’d release some heat, but cut your moles of gas in half (back to what I imagined at first).
I don’t know what to think of a mixture of monatomic H and monatomic O. By themselves, the H would want to become H2 and the O would want to become O2. However, the monatomic O, AIUI, would be insanely reactive, which raises concerns about the mix of H and O; I’m not a chemist, but my guess is that as soon as you turn off your dissociative death ray, you’d have a massive hydrogen-oxygen detonation. So you’d have all the energy of the massively compressed gas, plus the energy of that detonation. It’d be a damn big bang.
Agreed - the only unusual thing about the products is the fact that the un-bondulator ray suppresses them immediately reacting with each other. Apart from that, they’re just elements in their normal form.
For the record, this is based on a SF short story (can’t recall the name) where some guy creates a ray that does something like this (actually I think it was a pair of beams that produce the effect where they cross). The story describes the victim as disappearing in a ‘puff’ of gas and dust. I’m trying to work out what would actually happen, within what I perceive to be the set parameters of the story - as far as I can figure, it would not be safe to be anywhere very close to the victim
Sounds kind of like the disintegrator beam(s) from Larry Niven’s known space stories. Not exactly, but close. They were supposed to work by suppressing the charge on electrons or protons, causing matter to shred itself into a monatomic fog. And sometimes both types of beam would be used at the same time, causing large currents to flow between the target regions.
If that wasn’t what you were thinking of, and you can remember what the story was, I’d be interested to read it.
If we assume the hydrogen and oxygen will remain unreacted, then yes. The ideal gas law says that if you start out at 1000 atmospheres at room temperature, and then expand your gas mix to atmospheric pressure, the final temperature will be about 18K. The ideal gas law isn’t applicable for a large portion of this expansion process, but, it’s fair to say that the final temperature will be very low.
If the H2 and O2 detonate, then the final temperature will be warmer - but maybe not much so, given that the expansion ratio is so huge. Someone else can do the math…
I think it is safe to say that if you violate (or “suppress”) a whole pile of the laws of physics, the result is going to be very hard to predict using the remaining laws of physics.
The problem is deciding how much energy (and in what form) the result of applying the death ray is. If the atoms are prevented from recombining chemically - what happened to that potential energy? Are the atoms forever prevented from reacting, or does the effect go away? How long? Just for the time the beam is on?
Hmm, let’s assume that the positive charge of the proton gets magically suppressed. Then all we have to deal with are the electrons. I seem to remember that there are about 10[sup]28[/sup] electrons in a human of average size, which we’ll call 70kg. Since humans are roughly the same density as water, we’ll estimate that the human is about 70 liters of volume. 70 liters is a sphere of about 50cm in diameter. How much energy would it take to fit 10[sup]28[/sup] electrons into a 50cm-wide sphere?
Wait - you massively decrease the entropy of the system, do not change the enthalpy… and the energy doesn’t change? Those two sentences seem to contradict each other.
The results here are entirely dependent on the balancing mechanism, therefore per the OP the answer to this question is defined as complex and boring.
I couldn’t stop wondering about this, so after refreshing myself on electrostatics and Coulomb’s law and the like, and plugging a calculation into Wolfram Alpha, I got a result of about 5.4x10[sup]28[/sup] joules of energy for 10[sup]28[/sup] electrons packed into a half-meter-wide sphere without any counterbalancing charge. Wolfram Alpha helpfully informs me that this is about 145 times the energy the sun outputs every second, so it seems like it would be pretty dangerous to use a Niven-style disintegrator on a spherical human in a vacuum.