Lizard people that travel through space

It is the lizard person that travels through space, not the human. If the human tries faster-than-light travel, he always comes home replaced by a lizard person. You can tell the differences by getting to know them a little better.

It is an unfortunate circumstance of gravity and kinetic energy that space travel has proven fruitless to humans. If a human were to actually achieve faster-than-light speeds, a lizard person would find him or her, and replace his body with a lizard person. It is like if you through a sandwich too fast through the air, and the bread flies off in either direction, and only meat lands at the target. Except by the time the human meat lands, the lizard person has replaced the bread with scales. 

It is the lizard people that travel through space. The human can only find portals.