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:

1. 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.
2. 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.