Q: Tim, I read a column on your website about rock retaining walls. I’m having a hard time believing you can build a lasting wall and not use mortar between the stones. I’d love to just build a wall ...

It's perhaps the second week of your introductory physics course. Your instructor starts talking about friction and writes the following two formulas on the board. Then there is probably some sort of ...

There's rarely time to write about every cool science-y story that comes our way. So this year, we're once again running a special Twelve Days of Christmas series of posts, highlighting one science ...

Q. Tim, I read a column on your website about rock retaining walls. I’m having a hard time believing you can build a lasting wall and not use mortar between the stones. I’d love to just build a wall ...

Question: Tim, I read a column on your website about rock retaining walls. I’m having a hard time believing you can build a lasting wall and not use mortar between the stones. I’d love to just build a ...