Hazards in a Tea Cup
Something as simple as heating a cup of water in a microwave oven to make tea, can be hazardous. When a tea bag is added to hot water, it can suddenly boil violently and splash all over the place.
The danger arises because some of the water in the cup can become ‘superheated.’ Superheated liquids are at a temperature that is slightly above the normal boiling point, where liquid turns to gas. They can boil explosively if something is added to them, or if the cup containing them is disturbed. There have been cases reported where both the hot liquid and the container were thrown off the counter by the violence of the boiling. When any solid (such as a tea bag) is added, it provides the surface needed to form bubbles. These can form so quickly that the liquid boils explosively.
However, superheating doesn’t happen in a regular kettle because convection currents mix the liquid as it heats up, and there is usually a rougher surface, which helps bubbles to break up quickly as they are formed.
To avoid an explosively rapid rate of steam production from heating water in a microwave, you should leave the hot cup standing for a minute or two before touching the door. This will allow for some slight cooling, and for the heat to become more evenly distributed before the cup is moved or anything is added to it.
So next time you are in a big hurry, play safe and settle for cold fruit juice.
It’s deceiving to look in the microwave at a cup of superheated water and see only innocence. From our vantage point, there is no more danger here than in a cup of cold water.
Why should that be? Experience has taught us that dangerous water is moving water. A boiling kettle is hazardous. A frothy river is perilous. We learn to not see the inherent threat in still waters. We are using the wrong criteria, the wrong senses for the situation.
We need to learn about still waters that run deep or superheated water that can suddenly turn violent. Usually, this needs to be accompanied by some explanation, because on the surface, it doesn’t line up with experience. We have to imagine the picture of deadly undercurrents beneath placid rivers. We have to learn that water can be at boiling temperature without the bubbles.
There are other situations in life when our judgments and decisions are flawed because we are using the wrong benchmarks. It’s not enough to be able to assess the situation accurately, but it’s also necessary to respond appropriately.
British hedgehogs enjoyed centuries of successful adaptation to their surroundings because they responded to threatening situations by curling up into a ball. This prevented them from being identified as moving targets to predators. However, with the advent of the automobile, hedgehogs started to become road kill. They were accurate in assessing the threat, but wrong in their response to it and their numbers dwindled.
Many of the ways in which we assess our circumstances, have to do with the values we hold. Is my co-worker spontaneous or impulsive? Organized or obsessive? Funny or inappropriate? When we choose our descriptive terms, we do so against the background of our values. However, these gauges are frequently transparent to us. We don’t often reflect on our ethical system, our beliefs, our values, though we use them all the time.
Yet, we must ask if there is more to our moral system than mere survival instincts. If so, where do we look for such standards? Are human standards good enough? Is there something outside of the human sphere which anchors us beyond personal and cultural systems?
If so, who designed it or is it just a universal given?
Dr. David Humphreys and Debbie Hughes
© August 2004
