Miracle. All of it.


A small child next to us looked down at her snow-covered boots, then pointed to a duck that stood on the ice on the bank and asked her mother an extremely good question: “Why don’t his feet get cold?”…

It’s this: The bigger the temperature difference between two objects when they touch, the faster heat will flow from one to the other. Another way of putting that is to say that the more similar the temperatures of the two objects are, the more slowly heat will flow from one to the other. And that’s what really helps the ducks. As all that frantic paddling was going on, warm blood was flowing down the arteries of each duck’s legs. But those arteries were right next to the veins carrying blood back from the feet. The blood in the veins was cool. So the molecules in the warm blood jostled the blood vessel walls, which then jostled the cooler blood. The warm blood going to the feet got a bit cooler, and the blood going back into the body was warmed up a bit. Slightly farther down the duck’s leg, the arteries and the veins are both cooler overall, but the arteries are still warmer. So heat flows across from the arteries to the veins. All the way down the duck’s legs, heat that came from the duck’s body is being transferred to the blood that’s going back the other way, without going near the duck’s feet. But the blood itself goes all the way around. By the time the duck’s blood reaches its webbed feet, it’s pretty much the same temperature as the water. Because its feet aren’t much hotter than the water, they lose very little heat. And then as the blood travels back up toward the middle of the duck, it gets heated up by the blood coming down. This is called a countercurrent heat exchanger, and it’s a fantastically ingenious way of avoiding heat loss. If the duck can make sure that the heat doesn’t get to its feet, it has almost eliminated the possibility of losing energy that way.

So ducks can happily stand on the ice precisely because their feet are cold. And they don’t care.

~ Helen Czerski, from “Why Ducks Don’t Get Cold Feet” in  Storm in a Teacup: The Physics of Everyday Life



  • Image Credit: wsj.com – Agence France Presse / Getty Images
  • Inspired by Albert Einstein’s quote: “There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle.”
  • Related Posts: Miracle. All of it.


  1. Hmm…I had to read this twice to understand it. I wonder if the small child would have been happy with the answer, ’cause they’re ducks and they’re used to the cold’.😉

    Liked by 4 people

  2. Of course. Everone knows that, don’t they?

    Liked by 1 person

  3. Cool! 🦆🦆🦆

    Liked by 1 person

  4. because ducks enjoy the ice.

    Liked by 1 person

  5. roseanne333 says:

    Funny! TMI. It’s a gentle reminder that there’s so much to know and learn. And yes, every bit is a miracle. Happy weekend, David.

    Liked by 1 person

  6. I wonder if that child ever asked another question ???

    Liked by 2 people

  7. And this, my friend, is why my degrees are in art history rather than physics….

    Liked by 1 person

  8. Mimi, I miss the days when the answer “because I’m your mom and I say so” sufficed!😊

    I heard the author interviewed and she had a way of describing this complicated stuff so that it is easy to understand. I almost considered reading her book, then after having to read the passage a couple of times, decided against it. My “waiting to read” list is way too long!

    Liked by 1 person

  9. Ned Quinn says:

    Ha. Love learning little nuances like this. Aidan is loving it….

    Sent from my iPad


    Liked by 1 person

  10. The comments are cracking me up.

    Liked by 1 person

  11. Actually, I’ve always wondered about this too! And even though I did need to read it a couple times, it all makes sense! But mother nature is an incredible being. 💚

    Liked by 1 person

  12. Mmmm, good to know I guess! Don’t know if I could explain it quite so scientifically ha 😁

    Liked by 1 person

  13. Good to see I’m not the only one whose mind was blown. I’ll let you know in a week how many times i have to read it. It reminds me of this, which I think you may have posted recently. Hey David!


    Liked by 1 person

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