My 7-year-old daughter, Autumn, and me were discussing how an atom is made up of mostly empty space with a small nucleus of protons and neutrons in the “center” and electrons swarming about it. During the discussion, she asked an insightful question,
“Can an atom have two cores (two nuclei)?”
At first, the answer to this question would seem to be a resounding, “No. An atom can have only one nucleus.” But not so fast: Earlier in the week Autumn and I were discussing the decay of radium into radon and alpha particles (helium ions). During this process, the radium nucleus ejects a helium ion and becomes a radon atom:
That means, for the briefest of time, there is a radon nucleus and a helium nucleus still inside the “center” of the atom, i.e., two nuclei!
This was NOT an answer to Autumn’s question, however: My physicists friends would probably point out that the helium ion is not actually considered to be a nucleus of the atom, but just a particle that was being ejected from the atom, and hence does not count as a counterexample to the statement, “An atom has only one nucleus.”
We discussed this “counterexample” and it became evident that alpha decay was not what Autumn had in mind. What she was really wondering was if there was a situation where an atom could actually have two nuclei in a relatively stable state for a period of time (a period long enough and nuclei that were predictively-stable enough to distinguish them from the general “soup” of strong forces involving protons and neutrons). This is why Autumn’s question was insightful. It was a question I did not have an answer for, and was not sure physicists did either. I told her that questions like her’s, even if they prove not to generate something new, help move science forward.
To my physicists friends: Is there already an answer to Autumn’s question? It seems to me that, as the number of protons and neutrons in a nucleus increases, there does come a point where one could imagine the electromagnetic forces may “balance” the strong forces enough for weird behavior like double nuclei to exists, at least for short periods of time in certain highly controlled situations. However, I am happy to concede that there may be a well-known fact (to physicists) that rules out such phenomena that I have just overlooked in my thinking about Autumn’s question. Please leave a comment below if you have an answer–Autumn wants to know!
p.s. If you like Autumn’s question, you should see her in action by watching her videos at the Growing up with Eureka channel.
CHANNEL: Baldridge Theorems
© 2016 Scott Baldridge