Hi there.Extra terrestrial life probably does exist as simple, microbial-type life which thrive in extremely inhospitable environments such as the extremophiles deep in the earths interior. Intelligent or even a more advanced form is extremely unlikely.
The silicon based life from hypothesis faces two main problems:
- When energy is released from carbon it is excreted as carbon dioxide, Silicon forms Silica or sand a solid ,making silicon based lifeforms very unlikely.
- Silicon chains are highly unstable
On the other hand maybe we just don't understand the science well enough to understand how Silicon based life would work.