Candles and spaceships
On April 6th this blog will be celebrating it’s nine year anniversary (I can't believe I've been writing here this long!). Here’s a re-tooling of one of my old posts that I like. Next up I’ll reveal the number one most read post on this blog (and it’s not one I would’ve thought would be so popular).
Candle making fits into the category of fun things I did as a kid. We filled empty food cans with paraffin wax – the stuff that comes as a opaque block about the size of a deck of cards. A few crayon stubs went into each can, to create an array of colours. The cans were partly submerged into a bath of simmering water until the wax melted.
Armed with a thick piece of cotton string, destined to be the wick, tied around a pencil the messy part could begin--that is dipping into the wax. With each dip, a layer of wax clung to what was already there, incrementally increasing the diameter of the candle-to-be. I would rotate through the colours, creating what must have been delightfully gaudy candles (and likely a huge mess on the table).
Depending on my patience for dipping, the resulting candles ranged in size to just big enough to stand on their own to bulbus blobs barely able to fit in the can of wax. When they were fully solid, the fun part began: we could light them.
A flaming match held to the exposed end of the wick has enough heat to vaporize wax within the wick and react with the oxygen in the air. Within moments a teardrop-shaped yellow flame flickers to life. The heat from the candle's flame melts the wax, and the melted wax is drawn up by the wick, sustaining the flame. At its hottest, a candle's flame can reach 1400 degrees Celsius.
Heat vaporizes the wax creating a gaseous cloud where combustion takes place. Combustion is a series of chemical reactions converting molecules into new combinations – an inefficient process resulting in heat and light. Light, along with its cousin heat, signify the release of excess energy.
Compared to an incandescent light bulb, a candle produces 100 time less light, which is probably why candles are now mostly used to set moods, conduct rituals and provide light in power outages. These days, I rarely light candles, after all they are one of the leading causes of residential fires and they put soot and chemicals into the air I breathe. But, when I do have a reason to light a candle, I enjoy watching the flickering flame – I find something about it quite mesmerizing.
In my mundane earth existence, when I light a candle the hot gases formed are less dense than the air around them, and so they rise in a process of natural convection into the familiar teardrop shape. This natural convection hinders complete combustion, so soot forms which makes the flame yellow.
Out in my funky futuristic spaceship, where there would be no gravity (unlike the spaceships on TV), natural convection wouldn't occur, resulting in a perfectly spherical blue flame. And, the flame would require ventilation or it would smother itself as its temperature would be evenly distributed. On the plus side, the combustion would be complete - so no soot.
Flickering is another response to gravity. And there is even an equation for it: the frequency squared of a flame's flickering is proportional to the force of gravity over the diameter of the candle. Meaning a candle with a smaller diameter flickers at a faster rate than one with a larger diameter. So a candle on another planet (with different gravity) would flicker at a different rate than the same candle on earth.
A candle on my spaceship wouldn't flicker at all (I would have to be mesmerized by its pretty spherical blueness instead).