Why doesn't fire scale down?

In a past thread about the chances of a civilization of tiny people being able to prosper, somebody mentioned that because fire doesn’t scale down, it would be impossible for tiny beings to control it and limit their potential.

This question isn’t about the idea of a smurf-like civilization prospering :stuck_out_tongue: but rather the whole ‘fire scaling down’ thing. Is it true? Is it impossible to build a tiny little fire? What exactly is limiting how small a flame can get? And what is the smallest you can get it?

If you are really small, like the Incredible Shrinking Man (about one inch tall), a good sized cooking/camp fire would be about the size of one ordinary wooden match broken up into three or four “logs”. Those would burn up in about 20 seconds.

I know that had nothing to do with your question, I just like the idea of tiny people.

That’s actually an interesting point. I’d imagine that the scaling of the fire would be more dependent on the materials being burned. It seems reasonable to me that you could have a small chunk of charcoal and it could burn for a bit. However, just the size alone means that there would be a lot of surface area exposed for burning and not much volume, so it would burn quite a bit faster than a proportionally sized charcoal to a normal sized human.

Actually, nothing scales down, or up, beyond certain limits.

The giant ants in “Them” would have collapsed under their own weight. That’s why elephants are shaped differently than gazelle

The incredible shrinking man would have trouble with body chemistry down at that scale. That’s why

Filmmakers have trouble filming ocean scenes because it’s hard to show a small pool of water that behaves like the ocean. Whitecaps don’t develop, for example.

Remember that when you scale a fire down you aren’t scaling everything down. I’m talking about the molecular level. You may have tiny little logs but the cellular structure of the wood is as big as a sequoia. The viscosity of air is a factor too as airflow and convection will have an effect on how the tiny logs burn. That can be easily solved though buy burning different things. Soylent Gene correctly points out that a smurf scale log will burn out soon but a creative miniature guy could warm himself all night on a single tea candle.

Other problems crop up. Is there any reason to think a tiny human wouldn’t also have the same short lifespan as any similar sized mammal?

What if they make firewood from bonsai trees?

I found this old thread How small can a fire be? that may be of interest, but I could have sworn there was a more recent one.

Because of the characteristics of fire, it seems like technoligical advancement would be impossible for a race of tiny people (on earth or anywhere else).

If you cant build a decent fire, you’ll never forge metal or manipulate chemistry to build effective tools, weapons, and other materials. Therefore you, as an ant-sized being, you are condemned to being a hunter/gatherer wearing matted lint and spider fur clothing.

Also surface tension of water may make it impossible to drink.

I think there was an old Twilight Zone episode where some Earthling astronauts landed on a planet occupied by little beings…or vice versa.

To add a further complication, it can be supposed that the smaller you are the faster you experience time. So a grain of black powder that goes Poof in a second might seem like a cheery campfire to someone really tiny.

I’m not contradicting you, but where does your supposition arise from? I’ve heard it before but never found a cite.

Makes a lot of sense - your neural pathways are shorter; your limbs are quicker and easier to move (if a full sized human was to flail his legs back and forth at the rate that, say, a zebra spider does when running, they would simply fall apart).

While a husmurf would appear to be quicker and that may change his perception of time his matchstick campfire will need to last much longer to make it through a cold night on a not-scaled-down earth.

Sounds to me to be more likely The Phantom Planet a 1961 sci-fi film that was later MST3K-ized. An Earth astronaut (IN THE DISTANT YEAR 1980!) lands on an asteroid, for some reason breathes the “air” and is shrunk down to the six inch size of the local inhabitants. Stars Richard Kiel as the world’s tallest six inch alien.

The Twilght Z episode was humans on a planet of giants, the kicker was you thought the giant was an eathling until the end.

Life span is largely a product of cell division. Chimps are built like small humans, practically speaking, but live only 1/2 as long.

To me, that right there shows there’s no reason it couldn’t be done, but then for a little guy, you have to scale down the money too, right?

I mean how much does five gallons of paraffin cost? It doesn’t seem very cost effective.
(insert tongue in cheek smiley)

It sounds more like “Land of the Giants” to me, a 1968-1970 series. They used to show it on Sci-Fi years ago. The crew of a spaceship landed on an “Earth” where everyone was a giant (the crew members were small enough to stand in one of the giants’ hands. The earth in question was also technologically in say the late 19th or early 20th century (I don’t remember any cars.)

Actually Soylent Gene’s original point is one of the big reasons why fire doesn’t scale. Fire needs fuel oxygen and heat to propagate. Too little of any of those things and it goes out, too much and it will either become uncontrollable or go out.

The problem is that a fire can only have access to a small amount of usable fuel at any time. Too much fuel and the fire rapidly becomes bigger.

However when using a small fire we run into the second problem of surface area. A small amount of fuel will have a relatively huge amount of surface area relative to its size/energy content. Think of it as akin to having 1000 litres of ice cubes scattered on the ground on a hot day, or having one metre x metre block of ice. The ice cubes will all melt within minutes while the solid block of ice will last for days. That’s because the solid block has only a tiny amount of surface area in contact with the warm air while the ice cubes have a large amount.
So a small fire has a lot of surface area. The problem with this is that surface area also equals oxygen supply. A tiny fire will be exposed to huge amount of oxygen relative to the energy the fuel contains. As a result a small fire will burn very fast and very hot. That’s why we split kindling as small as possible, particularly when the wood is damp.

We can’t just take a normal size log and try to burn a little bit of it at a time because of the same surface are problem. One again this is why we use kindling to start fires. Apply a small fire to a log and the small fire will die before it can heat enough of the log to make it catch. And of course if it did catch the fire would become uncontrollable.
So as Soylent Gene suggested, a tiny man would need a stack of wood about a mile high just to see him through one night and he’d need to stay awake all night feeding the fire.
There are ways to make thing like the tea candle suggested above or a gas jet that produces a small, constant flame by controlling the amount of fuel available at any time. However they are all products of technology derived from fire. You couldn’t readily produce from a starting point of no fire.

Another issue is the ability to control a fire, and the rate at which a uncontrolled fire spreads.

I’d say they would be toast.