I’ve thought of a brain teaser. I think it’s original but it may have been invented by others in the past. So the two part question is to guess the answer and tell me if you’ve heard it before.
There is a mile long train tunnel with a single track running through it with no turns, side tracks, or cut-offs. A train enters from the tunnel’s eastern end and another train enters from the tunnel’s western end; both at noon on the same day. Both trains travel through the tunnel without stopping, slowing down, or reversing. The trains both safely exit without colliding. How do they do this?
The tunnel is either at the North or South Pole, where the Prime Meridian and International Date Line converge, and the concept of time and days means virtually nothing for trains running into a tunnel. How’s that?
The tunnel simply crosses the line between two time zones.
When the train entering the east-side of the tunnel goes, it’s only 11:00 AM on the west side. The train leaves the west side at, say, 11:05, and the next train enters 55 minutes later.
Situations like this are, of course, the reason why time zones were invented in the first place.
I guess I overshot the concept. But one train enters the west end of a 1/2 mile tunnel at noon on Tuesday, and another train enters the east end of the same tunnel on Wednesday at noon, both are going 45 mph, and neither stop, yet they collide head on. Polar tunnel.
