Did you know that scientists don't know how bikes work?

Scientists don't know where the moon came from.

Science hasn't even been able to define life, and some experts will tell you it's not

possible to define it.

That's why unexplainable from Vox is one of the best science podcasts out there.

It's a show about everything we don't know, and every week they explore scientific mysteries,

unanswered questions, and all the things we learn by going right up to the edge of our

knowledge and then continuing on.

New episodes are out every Wednesday.

Find unexplainable wherever you get your podcasts.

I had it in my mind that I wanted to propose to Sean during the trip.

You know, we've been together like three and a half years, and we're going to Vegas.

What more romantic place is there?

Next June, my friend Courtney decided to propose marriage in the world capital of spontaneous

marriage proposals.

And I was like, yeah, but I don't know how I'm going to do it.

I have, you know, I have the thing with me, but I don't know when or where.

Courtney waited and waited for the right moment until it was the last night of their trip

when they were hanging out in Caesar's Palace.

We're sitting at the bar and we got a couple drinks and we were kind of just killing time

before our flight.

I reached into my bag and I pull out this small leather box that I'd been holding onto all

...