What happens if an object which is almost travaling at the speed of light is trapped in a garage it normally wouldn't fit in?

Answer 1

Mainly obliteration of the garage doors. (That's a serious answer to the question as it's stated). But I see the point of your question. An object traveling at relativistic speeds is foreshortened along the line of its travel--the amount of foreshortening depending on how nearly its speed approaches the speed of light. As it stands, there are too many unstated conditions in your question for it to be answered, like how it wouldn't normally fit and in which dimensions, and how fast it's going (what percentage of c), and the relative motion of the garage. If it's trapped, then is the garage moving with it? If so, the realtionship between the length of the garage and the length of the object remains proportionally the same, so it still won't fit. If the garage is at rest and the object moving, it's not trapped unless the garage doors are closed, so a fairly noisy impact is imminent. The foreshortening is real, not illusory; the length of the object decreases at relativistic velocity in inverse proportion to the dilation of time at that velocity.

Answer 2

If an object is traveling at or close to the speed of light, it cannot be trapped in a garage that it wouldn't normally fit in. This is because as an object approaches the speed of light, its length contracts in the direction of motion according to the theory of relativity. Therefore, the object will fit into the garage even though it would have seemed too large when at rest.