As any science fiction fan knows, one of the most menacing and mysterious things in space is a wormhole. Wormholes are a possible consequence of Einstein's Theory of General Relativity. Einstein came up with the remarkable idea that mass warps space, and the bigger the mass, the more space will be bent. This strange conjecture was proved by Arthur Eddington in 1919, when he journeyed to the Amazon forest for the solar eclipse and proved that the Moon bent light from the SunA as it crossed in front. Theoretically, a wormhole could be formed when two or more massive bodies warp space and the fabric of space collides, forming a tunnel between distant places.
The easiest way to think about this is in two dimensions rather than three. Think of space as a piece of paper, which is bent over on itself. If a weight is put on top of the paper it will sag towards the centre. If there were another weight on the opposite side, then it would also sag towards the centre, if they eventually met then a wormhole would form, joining the two regions.
Although being sucked through the fabric of space does seem pretty menacing, wormholes would offer amazing possibilities to travel through space and time. Popping through a wormhole could bring distant galaxies to your doorstep. What's more, by doing this you are effectively travelling faster than the speed of light, and so by passing through a wormhole and back you could travel into the future.
No one knows whether wormholes exist let alone what would happen if you sent a spacecraft through them. If they do exist they could be very short-lived, and may not even survive long enough for a spacecraft to reach the other side. And if the spaceship did make it, its mass might cause the wormhole to snap shut, cutting the astronauts off for good. Maybe we gonna find another way but fot the time my sis is able to explain woemholes with apples ;-). If you want to know more go to Space-Science