Man without weight

1997/07/01 Bandres Unanue, Luis Iturria: Elhuyar aldizkaria

• Fisika

As Torricelli pointed out, “we live at the bottom of a sea of air” and if for any reason we manage to be a thousand times lighter and have less weight than the air, we should necessarily go out to the surface of that sea. We would climb a few kilometers to match the density of the air with ours. Then, our dream of living in freedom from mountains and valleys would crumble and fall, just as the house of cards falls: once liberated from the chains of gravity, it would fall under other forces, that is, under atmospheric currents.

The famous writer Wells explained to us a similar situation in a science fiction story. This will help us to better explain what we want to tell you. The subject of the story is that a fat man wanted to lose kilos in any way and it seems that the narrator had a wonderful formula for it. The chubby asked for the recipe and soon began to take it. One day the narrator passed by in front of the thick house and came up with a visit, sounding the door and seeing really surprising facts. Wells explained this.

It opened long after the door. I heard the key turn inside the lock and later heard the voice of Pyecraft (which was the thick name) saying: – Go ahead! I triggered the door trigger and opened the door. I, as is normal, expected to see Pyecraft, but... there was no one there! The room was completely upside down: the plates, both large and small, were mixed with books and writing tools; there were chairs pulling the floor, but Pyecraft wasn't! – I’m here! Close the door! said his voice. And then I found him: he was in the same upper cornice, beside the door, at the edge, as if someone had stuck against the ceiling. His face was down and reflected panic. – If something calms down, Pyecraft falls off your back and breaks your chin! I said it. This type of gymnastics is not for your age and body. But how are you tied? I realized that at that time I was not tied up and that there I was floating like a balloon full of gas. Pyecraft tried to free me from the ceiling and approach me dragging down the wall. He grabbed the frame of a picture, but began to relax and climbed back to the ceiling. He touched up and then I saw that all the outside of his body was stained with lime. This time with more attention he tried to go down the chimney again. "This medicine is too hard," said Marmarmarmarmar. I have lost almost all my weight. Then I saw everything clear. – Pyecraft I said. You needed a slimming medicine, but as always you were talking about your weight... You are a little bit and I will help you. And pulling the hand of the poor, he put it down. From the classroom he started dancing to stay. That was really curious! Strong wind One day walking I felt like I wanted to keep a candle. "That table," said Pyecraft, tired of so much dance, "is very hard and very heavy. If we could get under... That's what I did, but there it also moved like a captive globe. He did not stand still for a moment. "There's one clear thing," I said then, "that you don't have to go out into the street if you don't want it to go higher and higher. I told him that he had to adapt to the new situation and that he would easily get used to walking from the ceiling with his hands. "I can't sleep," he complained. I told him that with a tender mattress you could tie the somer, that with some chigolas we would nail clothes, sheets and blankets into the mattress. We placed a staircase in the room and placed the food on the library. We also invented a system to get down to the ground whenever we wanted to. On the top shelf we placed the Encyclopedia Britannica. Immediately the bulk picked up a couple of specimens and, with them in hand, came down. I did two days at home, with the hammer and the liver in hand, making some special gadgets, like the cable to expand the doorbell. When I was sitting next to the fireplace in his favorite corner, next to the ledge, while a Turkish carpet was nailed to the ceiling, an idea came to mind: – Hey, Peycraft! I got used to it. All this is useless! Put a lead liner on your clothes and go! Pyecraft almost cried with joy. "Buy some lead sheets and sew them inside the garments," I said. Wear shoes with lead soles, carry a lead case in your hand and forward! Here you will end up being captive, you can get out! And also, you won't be afraid of shipwrecks, if it ever happened to you, you can release the lead balloons and fly well!

All of the above seems to be in accordance with the laws of physics. However, in some passages of the story we have to show our disagreement. And the main reason not to agree is that even if the bulk loses all its weight, it would not rise from the air.

So it is, according to the principle of Archimedes. Pyecraft would rise to the ceiling if the weight of all its garments and the weight of those in its pockets was less than the volume of air that moves the circle. Calculating the weight of the air that moves the human body is not complicated, just remember that our weight is similar to the water mass of the same volume. Take, for example, a friend of 60 kilos and, therefore, the water corresponding to its volume will have the same weight. However, the density of the air around us is 770 times lower than that of water, so the weight of the air that the body moves is about 80 grams.

Therefore, although the weight of Pyecraft is 100 kilos, the weight of the air it displaces would not exceed 130 grams. Would the weight of pyecraft clothing and all things in the watch and pockets not exceed 130 grams? Of course. Therefore, the bulk would remain on the ground and, although the situation was not very stable, would not rise to the ceiling as the “captive globe”.

To be able to fly you should be completely naked. However, if he is dressed, he would behave like a doll tied to a balloon store, with a small effort or a simple jump and then, if there was no wind, he would start to go down slowly. Therefore, if we have to reward and applaud Wells certainly it is for his literary virtues, not for what he taught us about physics.