What does human vapor smell like?

Question

We've had a few STEM questions asking for the total wattage necessary for a laser to vaporize a person. I would like to focus on the human aspects of it, specially relating to sensory experience. The reason being that in one of my tales, weapons that can vaporize people exist and are common enough that they will be used a few times. I would like to describe the experience of watching these being used to the reader.

Now, I think I've figured out most of what a bystander watching from a safe distance would perceive.

They would see a bright flash, and then the victim immediatelly exploding.
They would hear a loud bang.
They would feel a very warm draft passing over their skin.

But I still need a general idea for the smell and taste. I could maybe figure it out on my own, but since the mortician won't allow me in the closest funeral home anymore a trip to the crematorium is out of question.

So does anyone know?

I expect a lot of different notes since different tissues have different amounts of water, fat and sugars. Is that correct?

Answer 1

I don't think it would smell like much, beyond possibly "burnt" or "ash" (if that even has a smell).

Humans are mostly carbon, hydrogen, and oxygen, with the hydrogen and oxygen mostly being bound into water. This means that if you had an arbitrarily powerful laser with the beam big enough that the entire human fits inside and "vaporize" the human, you'd be left over with super-heated carbon dust and water vapor. You'd get something similar to what comes out of a crematorium, so just ash as you might find in an urn. It would be sterile, and probably rather odorless too.

Answer 2

The closest reference I can find is to burning bodies.

Accounts from those having experienced the smell of burning bodies in concentration camps says its unmistakable and sweet. I have also found this reference, which I report

The smell of a burning body is the combination of burning skin, muscle, fat, hair, organs, spinal fluid, bacteria and even, possibly, bone. That means there’s a very complex smell to burning bodies, but it is one that is completely unmistakable and once you smell it you won’t forget it.

[...] Put all of these things together and it’s fair to say that a human body doesn’t have an easy to describe aroma when it’s on fire. There is a hint of pork/beef to it but it’s also sweet and often has an underlying sickness to it too and it can be so pungent that it even seems to become a physical taste.

One thing nobody disputes though is that it’s one of the most recognizable scents in the world and once you smell it, you will never forget it.

Vaporizing a body would probably get rid of some of the intermediate aromatic molecules which form during burning, but the only vaporization events of human bodies (Hiroshima and Nagasaki nuclear bombing) hasn't left accounts of the perceived smells.

Answer 3

Instantly vaporizing a whole person with a laser is a tremendously energetic event. The heat from said event would cause a thermal explosion that would kick up all the material within a significant radius. You would not smell the person, but you would smell all the dirt kicked into the air, all the smoke from anything around the core of the vaporization spot that would have remained cold enough to more simply catch fire, and probably a significant hint of ozone.

What you smell would most closely resemble a mixture a construction site and a bonfire... but the exact mixture of these smells will depend largely on where the person was standing when they were struck.

Answer 4

Can You even smell it?

Evaporating average human give You around 7000m^3 of vapour. It is hot. If You do that in building then walls will be destroyed and dust related to this overpower smell of body. If You do that in open field then shockvave survivors will be far enough to not smell rising cloud of vapours.

Answer 5

The crematorium is not going to get you an answer because they do not vaporize a body, they oxidize it at a much slower rate.

The most pungent ions are what would prevail, even though many different smells may occur from plastics or other wearables. But as others have said, consider that the energy to do this nearly instantly will be dissociating any complex molecules, so you will have mostly elemental gasses. 80% water will become H$_2$ gas and ozone. The carbon is a given, along with some nitrogen. But none of the ions with that sweet aroma of cooked bacon will survive this laser. All you need to do for an objective answer is vaporize a flea under an industrial laser (I volunteer Goodies for this gruesome task) and you'll have an idea. They're made of the same stuff.

Another quick way to test this is to build a jacob's ladder and fry a dead bug in the arc by holding it on the end of a long plastic rod. The smaller the bug, the closer your smell will be. You're trying to use the plasma to vaporize rather than cook.

Alternately, describe the smell of the biggest bug zapper you can find when a mosquito hits it, and no one will question you.

Having said all of this, honestly you need to think more about the stuff that will actually be cooked instead of vaporized. If they are standing on stone, or an asphalt street, or a cement sidewalk, there will only be enough energy to cook these instead of vaporize them (at least at a certain depth). These ions will put off a stronger smell than the elemental vapors, and every situation could be completely different.

I have to reiterate that what you smell will be far away from the victim, as that vapor will be too hot to smell, it will sear your nostrils.

Answer 6

No smell

Q: "the total wattage necessary for a laser to vapourize a person. "

A person won't evaporate when using current day high power laser

The effect of a heavy laser would be cutting a person in two halves, or perforating a person. It will be scorched on the wound sides, I don't think there will be relevant fire, smoke or smell.. except maybe when a laser is used at point blank, indoors. My reference for this is heavy industrial laser cutting equipment..

A person sized laser beam would yield vapor and ashes

Similar, but don't try this at home.

Suppose we have a human body size laser beam with 2 million times the surface hit by a heavy industrial laser (just under 2 square meters).. you'll end up with instant water vapor + a cloud of ashes.. In that case this answer also stands, there won't be time to oxidize anything slowly, yielding fire and smoke. The target will explode, the ashes will spread and fall to the ground.

The water vapor is gone, you'll smell the ashes. According to this source, human ashes are odourless,

https://farewill.com/articles/what-are-human-ashes-like

Answer 7

Kentucky Fried Human

Seriously.

The energy required for a phazer to vaporise someone is also going to basically cook and coagulate their proteins. The "vapour" you're describing is a horrific stew of carcinogens, byproducts of combustion, various ejected fluid and solid particles.

YUM!

You can see in the video how energy applied to flesh yields vapours of various kinds. This vapour does have a characteristic odor, and it is basically the smell of cooking. It also has a taste, kind of metallic, kind of umami rich.

For your story: it is an almost delicious aroma, if the true source of it remained hidden from the olfactor; and one that, even after many years, never quite leaves the nose.

Answer 8

This happens every day in surgery

And it basically smells like burnt hair.

Surgeons use electrocautery as a device to pass current through the body. Depending on waveform the diathermy will either cut through tissues, be used to stop individual bleeding vessels, or fulgurate, which looks like a Palpatine/Thor lightning effect. This concentration of current vapourises tissues. I only use it on muscle/tendon/ligament, so the smell from other tissues may vary, but the closest smell is to light a few strands of your hair.

Try it at home (strands of hair, not diathermy) and you’ll be able to mull over all the adjectives you need. Just don’t do it indoors as it really lingers.

Informally, I tend to call diathermy the ‘lightning stick’ at work, and ‘knife and fork’ for the scalpel and forceps.

Answer 9

blood and burnt hair (and probably furniture)

The laser is directional, and it cannot have exactly the energy to "vaporize a human body". The quantity of human matter in the path of the beam will not be the same in all the points of the beam, so if the beam intensity is enough to vaporize, say, a human chest or a human leg, it will vaporize a hand and keep on vaporizing. A human-shaped laser beam with variable intensity, while theoretically possible, goes against the YAGNI rule: if you use a megabeam to kill a human, that's because you don't have anything handier. If you have a man-vaporizing beam, you can get yourself one million man-killer beams for the same effort, or a single man-killing beam with one millionth the effort.

The "vaporization" will then be either incomplete or excessive; probably both in different areas of the target body.

So, what happens? The vaporized portions will smell like burnt protein and nitrogen oxide (an acrid, dry smell, almost indistinguishable from burnt hair because, well, hair are made of protein). There will be no cooking smells because target is vaporized where it is vaporized, and explodes where it isn't. The energy will be preferentially absorbed by water, which will flash into water vapour, exploding tissues away from the incoming beam. Those tissues will be almost raw, and therefore smell of blood (or other things - for example, in the case of the bowels...).

Then, the beam's remains will continue on their path and incinerate/vaporize whatever they find, which will likely be furniture. Depending on the composition of said furniture, all sorts of smells are possible.

However, I expect that a laser hit on a human body will be almost indistinguishable from the detonation of a largish, odorless bomb kept in close contact with the body (same sound, light, smell, and side effects).