Time Travel and Trains

So my physics professor once gave an example of time travel using a train, something about the train being stretched way out and the person standing on top of the train getting really really tall. Or something. As you can see I don't quite remember

I'm wondering if this is a common example when discussing time travel, or if this is something my prof. just pulled out of his hat? And if it is something you've heard of, can you re-explain it for me? It was rather cool, if I remember correctly.

I haven't heard that before. In fact, I don't think my teacher has ever talked to me of time travel. Lol.

I'm a little rusty on the subject, but I think what your teacher was talking about may have been time travel with gravity. When you go towards the event horizon of a black hole, the pull of gravity is stronger and you spin around the black hole faster. Eventually, you get stretched out, like spaghetti. What's this have to do with time travel? Well, the faster you go, the slower time goes for you or the less of an effect it has on you (I wish I remembered exactly. I think with gravity, the less there is the less of an effect it has. Satellites have to have their clocks adjusted in such a way so their clocks match those on the Earth.

One thing I do remember clearly is that, at the moment, their is no way to go back in time past the moment any time machine was made/activated.

Ah; I think that is more or less what I was thinking of. Thanks, Perra.