"Goldilocks & the Three Bears" and the neutron lifetime measurements

Submitted by kl3mt on Wed, 03/23/2022 - 19:40
Goldilocks & the three bears


If you are not familiar with the story, here is a youtube video of an abbreviated version of this famous children's tale.

Like many diligent parents, I read this story many times to my kids when they were young. The story is cute and there are many different measurement quantities (sizes of the bowls, the chairs, the beds; hot vs cold; soft vs hard) that help young children to learn about the mathematical concept of comparison. However, in reading this bedtime story, I often wondered what was the moral of the story. After all, the main character, Goldilocks, committed unlawful trespassing, vandalism, and theft; she escaped the crime scene without any consequences. So I looked up the moral of this story on google and got the following answer:

Respect the privacy and property of others and how your actions hurt others


Sure, this is what parents want their kids to get out of the story, but I doubt there are many young kids coming to this conclusion on their own.

Other parenting articles provide more credible analysis:

Kids identify with Goldilock's insatiable curiosity trying out new things. They share the excitement and the sense of adventure as she wanders into the woods on her own, and they identify with the awkwardness felt by Goldilock when she breaks things as a result of their still developing motor skills. Children also appreciate the comfort of taking a nap after causing a mayhem and then being forgiven.

Hmmm... makes sense. However, it appears that the story conveys different meanings depending on the perspectives of listeners. 

Well... since this is a make-believe story, we will run with it and have some fun.

Let's take the perspectives from the three bowls of hot porridge that the Mother Bear prepared. 

The hot porridge needs to cool to the right temperature so that the bears can have their breakfast. The fast-moving water molecules escape from the open bowls at a constant rate. This evaporative cooling should proceed as nature dictates---following the laws of thermodynamics---and the porridge would be ready for the bears' consumption when they return from their morning walk. However, this cooling process is disrupted if there exist other sources of loss. In this case, Goldilocks sampled the porridge and completely consumed the little bear's portion.

This feels a lot like the neutrons in our UCNtau trap. Neutrons should disappear at their destined beta-decay rate. Any loss other than beta decay would obscure the measured decay rate and give a wrong neutron lifetime.

Now we are talking.

Next, let's consider the Bears' experience.

The bear family came back from their nice walk, only to find that their porridge had been tampered with, and the baby bear cried: "Someone has been eating my porridge, .... and it is ALL GONE."

So they did a lot of investigating work: they examined the broken chairs; they followed the tracks to their upstairs bedroom to find that all the beds were unmade; finally, they discovered the source that created all this mess and ruined their nicely planned day. The culprit was this foreign entity called Goldilocks.

Well... this very much reminds me of the job as experimentalists tasked with precision measurements. We spent much of our time doing the detective work to collect data, examine the evidence, come up with models and reason, so that we could chase after the responsible criminal by ruling out possible suspects one by one. The goal is to design an experiment free of systematic effects that would otherwise disturb the condition of the experiment and obscure the result of our measurements. We have been working hard chasing away Goldilocks who eats our nicely prepared porridge, making our neutrons disappear at a rate faster than they ought to.  

So, there you have it:

The story of the three bears is the story of the neutron lifetime measurements.

The only difference is that our story is still ongoing. We have not yet found our Goldilocks (and take our sweet revenge). We are still looking, working tirelessly to identify the culprit that is responsible for the neutron lifetime puzzle.

Or perhaps there is no Goldilocks to be found in our apparatus. We might have secured our neutron trap well enough so that there is no weakness for intruders to break in.

Perhaps it is the other experiment that has leaks.