Chapter 18 Part 3 Joining the Army-2

Whenever I had free time while working in Los Alamos, I went to Albuquerque to visit my wife; she was in the hospital at the time.Albuquerque is only a few hours drive from Los Alamos. Once I went to see her, but I couldn't enter her ward immediately, so I went to the hospital library to read books. I saw an article in Science discussing scout hounds and how keen their sense of smell is.The author describes the experiments they have done, like hounds can recognize things that have been touched by people and so on.So I thought: Hounds are so powerful, don’t you know how sensitive our human sense of smell is?

When it was time to visit, I went in to visit my wife and said to her, "Let's do an experiment. Six Coke bottles over there (she left half a dozen empty Coke bottles for the cleaners to come and take away), you Haven't touched them for two days, have you?" "That's right." I lifted the empty bottles to her side, without touching them at all, and said: "Okay, now I'm going outside. After I go out, you take an empty bottle and hold it in your hand for about two minutes before putting it back. When I come back, I'll see if I can recognize which one it is."

I went out and she picked up a bottle and fiddled with it for a while - which was a long time, because I'm not a hound!According to that article, hounds can even recognize objects you just touched. I went back and looked, it was so obvious!I don't even have to smell it because it's not the same temperature as the other bottles, and it smells distinctly different. If you put your face close to it, you will feel that its moisture is heavier and warmer than other bottles.The results were so obvious that the experiment lost its intended efficacy. Then I looked at the bookshelf and said, "You haven't read those books for a long time, haven't you? This time, after I go out, take a book from the top, open it--you just open it once--and put It closes and puts it back."

After I went out, she did as I said, took a book, opened it, closed it, and put it back.When I got back, it wasn't difficult at all!You just have to smell the books.It's hard to tell because we don't usually talk about things like this, but you can tell which one it is just by putting each book up to your nose a few times - it's a little different from the others .Books that have been sitting on the shelf for a long time have a dry and monotonous smell.But if it has been touched by human hands, it has a dampness and a different taste. We did a few more experiments, and I found that hounds are great, but humans aren't as incompetent as they think they are.In fact, it's just that people's noses are too high off the ground!

At home, I've noticed that my dog ​​can sniff out my footprints and know where I've been, especially when I'm barefoot.So I also tried to do that: lying on the carpet and sniffing, see if I can tell the difference between the places I have walked and the places I have not walked?It turned out that I couldn't tell the difference at all; so in this respect, the dog is indeed much better than me. Many years later, not long after I arrived at Caltech, I went to a party at the house of Professor Robert Bacher, and many people from the school were there.Forgot how it started, but I talked to them about smelling empty bottles and smelling books.Of course they didn't believe a word of it, because I was always thought of as an expert on making things out of nothing.I had to perform in public.

We took eight or nine books off the shelves, being careful not to touch them with our hands, and I walked out.Three people each touched three books: they each picked up one of the books, opened it, closed it, and put it back. Then I ran back and smelled everyone's hands and every book—I can't remember whether I smelled the hands or the books first.I found all three books and only misidentified one person. They still didn't believe me, thinking it was some kind of magic trick, trying to figure out how I recognized books and people.In fact, many people know a similar trick: You pre-arrange a friend in the crowd, and you can get the answer according to the password he gave you.So they are trying desperately to guess who my accomplices are.

Since then, I have thought of a good poker trick.You can give the audience a deck of cards, walk into the next room, ask him to pull a card out of it and put it back, and you say, "I'm going to find that card, because I'm a bloodhound, and I just use my nose." Sniffing these cards will tell you which one you drew just now." Of course, after hearing this spell-like statement, they will never believe it, but in fact you are going to do just that! Human hands smell very differently, which is why dogs can recognize different people; you should really try it yourself!All hands have a damp smell, with the greatest difference between smoking and non-smoking hands; women's hands often smell of cosmetics.You can even smell it from someone's hands if they have some coins in their pockets and they've been handling them!