Given the fact that there are billions of stars like ours, it's

hard to believe that intelligent life exists only on Earth. In

fact, some scientists estimate that as many as 10,000

advanced civilizations exist in our galaxy, the Miky way.

This estimate is based on our understanding of how life

began on Earth and how Earth itself came into being.

The real issue is not the existence of life on other worlds.

The existence of an alien spacecraft requires much more.

It would mean that the aliens had the technology to travel

an enormous distance through space.

The fact that scientific theories have been wrong before

doesn't mean we can say that anything is possible. In this

case, for example, there is no evidence to indicate that

anything can travel faster than light. On the contray, all

the evidence is against faster-than-light travel. This is one

of the most fundamental laws of nature.