Make yourself feel better by learning about the physics of chicken soup

Illustration for article titled Make yourself feel better by learning about the physics of chicken soup

Some days, when you're feeling blue, it only takes a little thing to make you happy again. Today's little thing is a serious discussion about the physics behind the varying temperatures of vegetables in soup, and why tomatoes are always as hot as the inside of the sun.

Top image: Daryl Mitchell/Flickr

Human curiosity has given us explanations for the behavior of light and the evolution of the human race, and that's damn good work. But it's almost more inspiring when someone burns their mouth suddenly on their soup, looks into the bowl, and thinks, "By God, I am going to figure this out." It's even more inspiring when they write to a physicist, and the physicist answers them.


The question that burned in the mind of at least one curious person was, "If a bowl of soup is supposedly heated evenly all the way through, why do some vegetables, like green beans, seem roughly at the same temperature as the soup, but tomatoes go off like tiny nuclear bombs on your tongue?" What I like about the question was the story that has to be behind it. Sure, it started off with the person accidentally burning their tongue a few times. But before you write in to a scientists, you do a little double checking. How much deliberate, self-inflicted pain went into ascertaining that the tomatoes were hot under all kinds of conditions? We'll never know.

What we do know is the answer, because a physicist associated with the University of Illinois at Urbana-Champaign answered the question — which is proof of the inherent goodness of the world. The answer is two-fold. The first part involves physics. Tomato chunks have a thick outer wall of plant material around a watery interior. While the rest of the soup makes contact with the air or the sides of the bowl, losing heat that way, the tomato insulates its interior water, keeping it hot. It's a tiny edible thermos.

But don't a lot of vegetables keep their interiors warm? Why are tomatoes the only ones that set fire to your tongue? Well, this is where engineering comes in. Most vegetables are inefficient heat-delivery systems. They're mostly solid all the way through, which means you have to mash them up to spread that inner heat around your mouth. But a tomato's liquid interior doesn't need slow chewing and mashing. As soon as a tooth punctures it, it explodes its insides all over the interior of your mouth, flame-thrower style.

Okay, it's not the Laws of Motion. Still, the fact that someone thought of this, and pursued it, and that pursuit was ultimately successful, gives me a optimistic view of life. Maybe we will get to Mars after all.


Via Ask the Van

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Chicken soup is for noodles, kneidelach, chicken, and/or the vegetables you used to make the stock (carrot, celery, parsnip). What is this tomato nonsense?