If Fire is not Solid, Liquid, Gas, Plasma, What is it?

Flame cover

Fire, that sparked the evolution of humanity, as it was the very fire that evolved early men into humans. It gave us the ability to cook our food, produce heat, and utilize it as a weapon. Prior to it, primates relied on plant life and couldn’t consume protein-rich meat essential for survival in cold climates, finally, the smashing of two stones sparked both the fire and the brains of primates. Slowly it was controlled and a whole new level of possibilities was unlocked to us. Industrialization was only possible because of fire, but do we know what it actually is?

What is the Fire’s State of Matter?

Sitting around the campfire, staring into the mesmerizing dance of the flames this question comes to mind, what is it exactly? We have been using it for centuries in one form or the other, whether it is sitting around a campfire or using it to light candles on a fancy dinner. It obviously is not solid as you can see it taking form and moving. It isn’t liquid either because it doesn’t have the consistency of a liquid and neither does it flow. Then it must be a gas right? Not exactly. Though it does resemble and mimic gaseous properties, it eventually fades away once the fuel has been exhausted or external factors such as water are applied, whereas, gases constantly remain present. Then it surely is plasma, the fourth state of matter. This isn’t it either. As plasma is created when particles are superheated, and the electrons are stripped from the atoms, Sun exists in the form of plasma, plus plasma doesn’t stably exist on Earth. While the fire is hot, it is not as hot as the Sun. So what is it?

Matter states-compressed

Representation of each state of matter.

Turns out the fire is not really a matter, it is actually a process. A process of combustion, where the gases and solids are burnt in a chemical reaction. While there are other chemical processes occurring around us as well, why fire is so impactful on us is because of its significance to our evolution. As our brain still links the fire to something that is necessary and soothing we are intrigued by it so much, also, it is a complete sensory experience for us. We see it, feel it, hear it, and smell it (whatever is being burnt).

Combustion is the result of a chemical reaction that occurs between various substances which mostly contain oxygen. This reaction is followed by the release of energy in the form of light and heat. As an example, when you try to light a matchstick, you rub it against the red strip, friction occurs and this results in a reaction on the head of a matchstick which sparks and lights it up. Now that you have a lit matchstick what would happen if you put it in campsite logs?

Matchstick burning

A matchstick burning.

Firstly, the temperature of the logs had to increase to the point where they can actually ignite, but fortunately, this happens quickly. Once that happens the cell walls of the logs start to decompose which releases sugar molecules of the wood. Here’s the fun part, though logs are dry on the outside there is still some moisture present within them, and when the log is burnt this moisture turns into vapors which try to escape into the air by expanding and cracking the surface of the wood that gives us that satisfying and calming sound of a campfire. Though flames want to expand and rise up as well, due to the gravity they stay locked to the fuel source and this gives the fire its characteristic curvy appearance. Speaking of appearance the color of the flame is due to the temperature and how much the carbon particles are being burnt. The standard yellowish-orange campfire flames burn fewer particles and are less hot comparatively, while the flames that burn blue are higher in temperature and burn efficiently.


A campfire burning.

Flames even after all these years is still as mesmerizing and fascinating as it would’ve been the very first time it was sparked. Finally, we know it is not a matter but a process. But more importantly, we still burn wood like our ancestors and to this day it gives us peace of mind.


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