Dr Karl Kruszelnicki, renowned author and science commentator answers listeners questions with Phil. Today he answers a Question from Denise on "If a tree falls in the forest and nobody saw, did it happen?"

<p>Dr Karl Kruszelnicki, renowned author and science commentator answers listeners questions with Phil. Today he answers a Question from Denise on "If a tree falls in the forest and nobody saw, did it happen?"</p>

Join Phil O'Neil from midnight to 5.30am Tuesday to Friday.

<p>Join Phil O'Neil from midnight to 5.30am Tuesday to Friday.</p>