curious

[UrbanXrisis]

is it true that if a spacecraft travled into space from Earth, it will ultimately reach the other side of the Earth (supposing it travled though the universe)?

[James R]

It might eventually if our universe is topologically closed. Consider an analogy:

The Earth's surface is a 2 dimensional topologically closed surface. If you set out in a particular direction and travel far enough, eventually you'll go right round the Earth and end up back where you started.

Similarly, it is possible that our universe is a 3 dimension topologically closed space. If that is true, then if you travel out into space in a particular direction, eventually you will "wrap around" and end up back where you started.

Recent astronomical observations seems to suggest, however, that our universe is not actually closed.

[UrbanXrisis]

What observations are those?

[HallsofIvy]

Notice by the way that it would be incorrect to think that you would arrive at the "other side of the earth". I feel sure that the time required to "circumnavigate the universe" (assuming such a thing is possible), the earth would have rotated enough that you could might well arrive at any point!