Built on Facts

Weddings all around for my family this week. I’m in my hometown with some time to kill this summer before my TA duties resume in July, which gives me the opportunity to catch up with old friends - one of whom was married this weekend. My parents went to a different wedding of some friends of theirs, who had the advantage of a budget roughly an order of magnitude greater than the wedding I attended. But of course marriage is (hopefully!) about love rather than money, and I wish them all the greatest happiness.

My favorite moment of wedding drama is when the audience is asked if anyone has a reason that the couple should not be married. No one ever does, but it’s always a fun moment of suspense. Sadly this tradition is an endangered species, and was not featured at this particular wedding. Presumably few people want to take their chances, though you’d think if a person were really determined to interrupt he (and it’s always a he in the movies) would not be deterred simply by not being asked.

But there’s often another moment of drama which is wholly unintentional: the lighting of the unity candle. If you’re not familiar with this tradition, there’s two candles set alight before the ceremony for the bride and groom. At a specified moment, the bride and groom use their candles to light a larger “unity” candle. Once done, they blow out their own candles to symbolize that they are now joined as one. Or sometimes they don’t, to symbolize that they will continue to love their families. Don’t ask me, I don’t make this stuff up. Here’s what the candles look like:

The unity candle is always brand new, with the delicate equilibrium of capillary action and convection not yet established in the length and saturation of the wick. The new wick is thickly coated, making movement of liquid difficult. Reliably lighting a new candle in one attempt is difficult under the best of circumstances. But it’s a wedding. There’s often a hundred or more people densely packed into the chapel. Each produces a few hundred watts of body heat. The air conditioner is turned on, and vents are often located near the front where the candle ceremony is taking place.

I’ve been to quite a few weddings with a unity candle, and though I haven’t been bringing data notebooks to the ceremonies I’d estimate the failure rate for unity candles is at minimum around the 1 in 4 mark. The symbolism is what really kills things. To light a unity candle and blow out your own only to have the flame symbolizing your love gutter pitifully and die within seconds is always embarrassing. Doubly so when the ancient majesty of the ceremony has to be restored with a kitchen or cigarette lighter. I am at least happy to report that none of this happened at this wedding, though the unity candle dwindled down to alarming levels before rebounding to a vigorous equilibrium.

Do I have suggestions to fix this? Yes I do. Just as a successful wedding treats the people involved with respect and consideration, a successful unity candle will have to treat the physics of the situation in a realistic way.

• First, how about a statistical analysis of the first-light success rates of different brands and varities of candles in different conditions? This is impractical for a single couple, but the weddings are something like a $40 billion industry and so I’m sure somebody has the money to do some tests. Maybe one of the wedding magazines. This suggestion is just Science 101. Repeatability is exactly the thing that’s needed.
• Second, a candle relies on generating enough heat to keep a self-sustaining cycle of melting and capillary action. When it’s first being lit, there is no hot wax pool and thus the new flame hasn’t got a lot of power to waste into a turbulent atmosphere. How about stationing someone to turn off the air conditioner about a minute before the candle is to be lit?
• Third, cheat the system. Physics is just rules, and if you can make the rules work for you then you’re golden. The problem with keeping a new candle alight is almost always excessive heat loss. If you can come up with a way to artificially increase the heat produced then you’re not at as great a risk from power dissipated in air currents. Try this: drill and remove the candle wick. Remove the wick from a trick re-lighting birthday candle and replace it in the unity candle. These trick candles work by including a thin ribbon of magnesium within the wick. It’s more or less shielded from the oxygen in the atmosphere when the candle is properly burning, but when the candle is blown out the magnesium begins to combust from the heat of the remaining ember. The comparatively large amount of heat generated by these sparks is sufficient to relight the candle. I wish I could say I thought of this idea, but in fact I came across this when doing a bit of reading about unity candles for this article. I have no idea why this does not seem to be in common use since it’s a really great idea.

It’s bit off the beaten path, but as we live in nature we’re always subject to its laws and ought to know how to deal with them. For better or for worse, in sickness and in health, ’till death do us part!