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Ask Dr. Universe physics
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How do cats climb? – Jake, 7, Wisconsin

Dear Jake,

Sometimes, when I’m working on a tricky question, I scale the tree outside my office. It helps me focus.

I asked my friend Steve Lampa how cats like me do that. He teaches small animal anatomy in the College of Veterinary Medicine at Washington State University.

He told me it’s all about a beefy backside and razor-sharp claws.

“First cats jump and propel themselves with their rump and hind limbs,” Lampa said. “Then they anchor with their claws—which are like grappling hooks. Domestic cats actually have sharper claws than their wild counterparts.”

The jumping part of the climb involves powerful muscles, especially … » More …

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What are protons made of? – Dean, 11, Utah

Dear Dean,

There’s a pencil lying on my desk right now. It’s not much to look at, but what if I could zoom way in and see the protons and other itty-bitty stuff inside it?

My friend Ryan Corbin told me it would be like looking at a bubbling soup of fundamental particles. He’s a quantum physicist at Washington State University.

He told me that protons—along with neutrons—form the nucleus in the middle of an atom.

“Atoms make up all the stuff that we see,” Corbin said. “An atom has neutrons and protons in its nucleus. Protons have a positive electric charge. Neutrons … » More …

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Dr. Universe: Can a shadow make a shadow? – Aven, 7, Palouse, WA

Dear Aven, When we look around our world, we can find all kinds of shadows. One way we can explore the answer to your shadow question is with a little experiment. My friend Anya Rasmussen, a physics professor at Washington State University, told me all about it. First, you will need to cast your shadow on a wall. Rasmussen reminded me shadows form when an object—such as your body— blocks light and keeps the rays from reaching a surface—like a wall. Read More ...