So, after all this time, have we ever actually found evidence of alien life on Earth? It's a question that gets to the heart of our place in the universe. For more than fifty years, we’ve been looking, and despite some tantalizing clues, the answer is still no. We don’t have a single piece of reproducible evidence. What we have is a fascinating story of discovery and disappointment, a lesson in how science separates a true signal from wishful thinking.