The most famous tunnel is the thirty mile "Chunnel" between England and France. The Chunnel is actually two separate tunnels, connected by cross passages.
When a train enters a tunnel, it compresses the air in front of it like a piston. Air in a tunnel can't be simply pushed aside--the tunnel walls are in the way.
Have you ever had a mole out in the backyard that spends all day digging tunnels through your lawn? Try to be too mad, it's just looking for food.
When you experience something new, do you know what happens to your brain? Find out on this Moment of Science.
Why don't ants drown every time it rains? Find out on this Moment of Science.
Once flour is mixed with wet ingredients, strands of gluten protein in the flour stretch out and link up with other protein molecules.