People like to confuse themselves with questions. Questions arise differently and begin to torment him from early childhood: Where does Santa live? Where do children come from? What happens if you put a light bulb in your mouth? If a whale fights an elephant, who will win? Where to get money for food and mortgage? What is the meaning of life and is there life on Mars?
Recently, one of the same small and annoying questions came to me: How can the workers of the N-CKoy network of stores so incredibly accurately calculate the number of pieces of cheese, independently packaged by the store into the food film, that with the twelve-hour storage period assigned after the package, there is no shortage of it on the shelves, just as there is no mountains of cheese in garbage containers? A natural, but not a good idea has been stolen – do the shop workers repackage yesterday’s cheese at the beginning of the next day again and do not mark it again? No, it cannot be. Simply, it is somewhat strange to see that a whole shelf of appetizing cheese sectors, still lying in the evening with labels with the expiration date "Today", disappears at night, and in the morning appears on the shelf already "fresh" cheese with the fresh labels "Today". The cheese fairy? most likely.
The day tormented me this question, the second. Of course, as the lawyers say, the proof of guilt lies on the side of the accusation. But how to prove? And I remembered a book from my childhood (there was such a fun before - books to read) about Robert Williams Wood - a talented, bright and humorous physicist-scientist. This is a moment in the life of a scientist.
In the university pension for a long time among student residents there was a terrible suspicion that the morning hot is prepared from the remains of yesterday’s lunch, collected from plates. The suspicion was very natural, as the fried meat for breakfast always followed the steak the day before. But how to prove it? Wood scratched his head and said, “I think I’ll be able to prove this with the help of a Bunzen burner and a spectroscope.” He knew that lithium chloride was a completely safe substance, very similar to ordinary salt in appearance and taste. He also knew that the spectroscope could detect the smallest traces of lithium in any material if it was burned in a colorless flame. Lithium gives a known red spectral line. When the students were served a steak for lunch the next day, Rob left on his plate a few large and seductive slices dried with lithium chloride. The next morning, the breakfast particles were hidden in the pocket, taken to the laboratory and burned in front of the spectroscope. The betrayal red line of lithium appeared - weak, but clearly visible. The deception was uncovered.
But back to our cheese. Wood’s method didn’t suit me. I made it easier. Shortly before the closure of the store, I approached the shelf I was interested in, took one of the pieces in my hands, made sure that the expiration date is tonight and put it in the previous place. And the next morning, entering the store right with its opening, I within a few seconds found my yesterday’s piece and, having been reliably convinced that it was it, bought it. The cheese was “today.” You may ask, how could I be sure? And everything is very simple: on the eve of the evening, with the blade of the office knife, I made a careful undetectable piercing and inserted a small neodymium MAGNIT into a piece of cheese.
The next morning, with the usual old pioneer compass, half hidden in my palm, I had no trouble taking the cheese in my hands, literally from the second attempt to find exactly the piece that I remembered and marked the evening. At home, I was convinced that my suspicions were justified.
The risk that one of the buyers would break a tooth on the magnet was minimal, so the interval between putting and removing the magnet was minimal. The bladder and the magnet are pre-sterilized with alcohol.