From The Desk of...The Chief Scientist

"Great Balls of Not Fire"

Written by Paul Sutter on Monday, 05 June 2017. Posted in From The Desk of...The Chief Scientist

Some weeks ago I was chatting with a couple members of COSI's floor faculty team about meteors (they were doing a tabletop meteorite demo, so this conversations wasn't totally unwarranted), when the subject of fire came up. Meteoroids that come screaming through the Earth's atmosphere are very bright, emitting a lot of heat and light, so it naturally leads to the question: are they on fire?

When a piece of space rock intersects the orbit of the Earth at the exact wrong time, it's typically traveling at a few tens of thousands of miles per hour, and that only increases in its final moments. And even though our upper atmosphere is only a tiny fraction of the density of our surface-level air, that speed is sufficient to cause a ton of pressure and friction.

Friction from the rubbing of air against the meteor, and pressure as the rock pushes on the air directly in front of it during its passage. Both of these processes generate a lot of heat; enough heat to ionize both the air and the meteor material, ripping electrons off molecules and causing them to glow.

The air will stay ionized for a few moments after the meteoric passage, forming the familiar trail. Bits and pieces of the meteor itself will get stripped away - a process called ablation - leaving a glowing aftermath in its wake as well.

But fire is not involved here. Fire is a chemical reaction between oxygen and a fuel source, and the physics on display in a meteor shower are based on different, and far more violent, processes.

"The Dark Matters"

Written by Paul Sutter on Tuesday, 30 May 2017. Posted in From The Desk of...The Chief Scientist

An anonymous question appeared on my board recently: if most of the matter in the universe is "dark", why can't we detect it via other means, like gravitational lensing?

Indeed, we do! From our understanding of general relativity, the presence of matter and energy warp and flex spacetime like a (four dimensional) rubber sheet. And beams of light like to travel in straight lines, but the spacetime "underneath" them is warped, forcing the light to follow curving paths. This means that a massive object can bend light around it like a lens...hence, gravitational lensing.

The measurement of this effect around the sun was one of the first pieces of evidence that Einstein got it right, and now we use it routinely to study matter all around the universe, including the dark kind.

"Dark" matter is really invisible matter - it turns out that most of the matter in the universe simply doesn't interact with light. We're not exactly sure what it is yet, but tools like gravitational lensing are helping us to study it. Even when we can't see it directly, it bends the path of light around it, so we know it's there and we can learn more about it.

"Aliens in the Ground"

Written by Paul Sutter on Monday, 22 May 2017. Posted in From The Desk of...The Chief Scientist

Recently a Columbus Dispatch reporter interviewed me about the growing excitement for COSI's new dinosaur exhibit, opening this fall. He wondered why dinosaurs were so dang fascinating.

I know I was obsessed with dinosaurs (and space) growing up, and seriously considered going into paleontology. And I guess I'm not alone. So what's the attraction?

To me, thoughts of dinosaurs run parallel to thoughts of extraterrestrial life. We're constantly inquiring if we're alone in the universe, and if there is life out there, what forms and shapes it could take. But buried under our feet are the fossilized remains of fantastic - almost mythical - creatures.

Massive beasts as long as school buses, fierce killers with teeth longer than my hand, flying and swimming creatures that are almost too big to comprehend. The dinosaurs and their kin have no real living analog to compare them to. Birds are descended from them, but only a few thin lines of the full variety of dinosaurs survived the extinction event 65 million years ago.

I think dinosaurs are fascinating because a) they're so different, and b) they're dead. It's only by careful reconstruction that we can even begin to imagine what they were like in real life. To us, they might as well be aliens.

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