Sometimes it must be a drag to have a mom with a physics degree.

We were on the way to school this morning, a truck in front of us.

"There's a generator!" Joe announced, spotting the piece of equipment in the bed. My heart swelled a little with pride.

The sight of the generator must have set his wheels a-turning, because soon he was yammering about his new idea: In the event of a zombie apocalypse, he could take two electric generators and using them alternately to power the other one, and somehow end up with "infinite electricity." I missed a lot of the details, but as I have a good understanding of that pesky concept called the conservation of energy, I was pretty sure his idea wouldn't work.

After voicing my doubts, I asked him, "How does it create electricity? Does it use gas?"

"No."

"If it isn't using gas, how is it creating the electricity? Is there a motor, and if so, what is it powered by?"

"Electricity. It's an electric generator, Mom."

I then tried to explain to him that if one generator was using energy to power the other one, but you also needed to use that energy for other things (say, powering a light), you would lose the energy eventually- like pouring water back and forth from one glass to another while taking drinks.

He wasn't buying it, and was getting frustrated with me, because obviously, I didn't understand his genius idea.

After I dropped him off at school, I felt bad. Who was I to shoot down his ideas?

I remember not so long ago, discussing with a friend how great it would be to have wireless power. But, silly me, I thought it would never happen. But it exists. So who knows.

Sometimes, a kid can't (or won't) listen to his mom. That's okay. Someday, he'll come to understand the conservation of energy on his own. And someday, he will probably engineer something I thought would be impossible- because he dreamed big and ignored his mother's doubts.