# "ELI5: Angular Momentum"

Written by Paul Sutter on Monday, 13 March 2017. Posted in From The Desk of...The Chief Scientist

Jarod Smith, a member of the COSI on Wheels team, asked me for help in crafting a quick-and-easy way to explain conservation of angular momentum to young kids, and more importantly sometimes to their parents.

The topic comes up in a fun and simple demo. Sit on a chair that can rotate, and hold a spinning bicycle wheel in your hands. Flip the wheel over and presto-chango you start spinning in your chair. Magic! I mean, science!

I like to think of momentum as the amount of "oomph" an object has - how much it can pack a punch if it were to hit you. A small object (like a bullet) traveling fast enough can hurt, and a big object (like a truck) can be a pain pretty much no matter how fast it's going.

Angular momentum is then oomph going in a circle. It's conserved, which means the total amount of oomph must be the same.

For very young kids, I just refer to it as spin. The bicycle wheel in your hands is spinning really fast in one direction. That's the total amount of spin that you+wheel can have. When you flip the wheel over, you're taking away the spin in that direction, so some has to be added: you yourself start spinning to compensate.

Ultimately, while we can explain what's going on as best we can, I think in some cases it's sufficient to let the demo do the talking. Kids are developing an intuitive sense of angular momentum conservation, and that's something we can build on when they're older.

# "The Great American Eclipse"

Written by Paul Sutter on Monday, 06 March 2017. Posted in From The Desk of...The Chief Scientist

Save the date: on the afternoon of Monday, August 21st, the moon will cover the face of the sun, the day will turn to night, and it's time to party!

A total solar eclipse is coming to the US, and the whole nation will get to enjoy it. Something like 95% of the population will be within range of at least 3/4 totality, including Columbus. In our city we'll get between 85-90%, so at 2:30 in the afternoon the sun will just be a thin sliver in the sky. As I type this memo, we're putting together a plan involving COSI and community partners like OSU's Department of Astronomy to make sure as many people as possible get to safely enjoy nature's spectacle.

But I won't be in Columbus on the 21st. I'll be in Nashville. The line of totality - where the sun is 100% covered by the moon and the corona becomes visible - stretches from the Oregon coast, over the Rockies via the Grand Teton National Park, through the great plains, across the Appalachians, and out through South Carolina. And Nashville is the only major city along that path.

I'll be leading a bus trip to see the total eclipse, then we'll take in the sights and sounds of Music City for a few more days. And I'd love for you to join me! We're infusing the trip with all sorts of fun COSI activities, and I'll be there during and after the eclipse to answer your burning (ha!) questions about the sun. COSI team members are more than welcome to join the fun, and you can check out cosi.org/adults for more info.

# "No Other Like Emmy Noether"

Written by Paul Sutter on Monday, 27 February 2017. Posted in From The Desk of...The Chief Scientist

Let me tell you about Emmy Noether, perhaps the most important mathematician that you've never heard of. I was prompted to share this by Chris Hurtubise, COSI's Senior Marketing Director, who asked me who was my favorite female scientist of all time. Of course some heavyweight contenders immediately came to mind - Caroline Herschel, Marie Curie, Vera Rubin, and many others - but after some thought I realized perhaps the most important woman in science wasn't a scientist at all.

Coming into prominence in the early 20th century, she faced the usual barrage of sexism and discrimination, having to fight for every educational opportunity and position. But her work was so remarkable and groundbreaking that it couldn't be ignored, and she quickly found herself supported by academic allies that helped promote her and her research.

Noether contributed to many fields of math, but one area in particular laid the groundwork for our entire - and I'm not exaggerating here - modern conception of physics. She discovered a fundamental connection between symmetries and conservation laws, and that's a big deal.

Here's an example. The COSI floor faculty rely on the fact that they can do the same demo day after day, and assuming they set it up correctly every time, they'll get the same results. Thus there is a symmetry in time for the laws of physics as applied to those demos. That symmetry, by the eponymous Noether's Theorem, leads to the principle of conversation of energy.

And the fact that you can pick up the experiment and get the same result on the opposite side of the building? That's a symmetry in space, which leads to a conservation of momentum. The equations of electromagnetism have a certain mathematical symmetry, which leads to a conserved quantity that you may know as electric charge. And on and on.

I'm barely scratching the surface of the significance of her insights. To really give Noether her due will require a whole new post. Next time...