I’ve never personally seen an electron. I’ve used an electron microscope to see very small things, and I believe in electricity because motors run, lights go on, spark plugs spark, and my older brother once got me to stick my finger in a live Christmas tree bulb socket. I adore and use the rules and units handed down by the likes of Watt, Faraday, Tesla and Ohm. But, I have to accept the observations of other smart people to acknowledge that the stuff called electricity comes from moving electrons, and isn’t the smoke that leaks out when I make a mistake.
When we write and choose articles to publish in Control, we try to have some that feed the interests of PhDs, often with equations that I don’t understand, as well as articles that build directly on the basics. We think everyone should find something useful, but we can’t expect that anyone will value every article. It’s a delicate balance.
In practice, we assume some level of prior knowledge and experience, or at least the ability and interest to look up an unfamiliar concept. So, I was quite amazed when I saw a question about the mechanism of global warming in part 1 of Béla Lipták’s current series of columns.
The reader asks how global warming could be caused by human consumption of energy, when all the energy we use is only a tiny fraction of incoming solar energy.
He apparently is unfamiliar with the greenhouse effect caused by certain atmospheric gases such as CO2 and methane. At first, I felt at fault because, due to space limitations, I had cut some figures that Béla included to illustrate the greenhouse effect. I thought they were unnecessary for our audience—the text still was clear about the mechanism.
But who among Control readers would not know about the greenhouse effect, and also lack the curiosity or ability to look it up?
Then I thought perhaps the reader didn’t represent our audience—that he had wandered in via social media, with no scientific background. Maybe a high school student, or underprivileged or poorly educated person from another country, perhaps a different hemisphere.
But as you can see in his letter, this reader is obviously capable of complex thoughts and calculations, and has significant command of the English language. (His comments also are trimmed for space, there’s quite a bit more at the above URL.) A quick check on LinkedIn showed me that he is a high-level engineering manager, with a BSEE from Penn State.
Alarmed that such a person could ask such a question, and back to blaming myself, I notified Béla and offered my apology for cutting the figures. He posted the reply you can find on page 12, again edited for space and available in full at the URL.
I thought Béla would respond with information about the greenhouse effect, but although he is a nice guy and very wise, for some reason, he didn’t directly answer the reader’s question. So, I feel compelled to atone by explaining it here:
As you surmise, the earth is not significantly warmed directly by the release of energy due to human consumption. The earth’s temperature is the result of the energy balance between incoming and outgoing solar radiation. As you mention, incoming solar radiation is enormous compared to human consumption—if a significant portion of that radiation were not reflected or quickly re-radiated, we’d all be burned to crisps. Retaining a small and increasing percentage of that energy, due to the effect of greenhouse gases, is what’s raising the temperature of the earth. For more about the greenhouse effect, visit https://climatekids.nasa.gov/greenhouse-effect.
It’s a delicate balance.