Uploaded December 2018 | Updated September 2026, 12 hours ago

---

At first glance, it seems as though paradoxes, or contradictions, arise in special relativity. One of these is known as the train (or ladder) paradox and comes from the introduction of length contraction. As a train passes through a tunnel, the two reference frames (train's and tunnel's) experience very different events. If we rely on our classical intuition, it seems that two different realities unfold in the two different reference frames. But how can this be? As it turns out, we can use the Lorentz transformations to show that there is nothing wrong with special relativity, and the problem lies with our intuition.