Imagine a world where infinite copies of you are playing out every storyline of your life. It sounds like a plot stolen straight from Hollywood, but far from it. This is the multiverse. Until very recently the whole idea of the multiverse was dismissed as a fantasy, but now this strangest of ideas is at the cutting edge of science. And for a growing number of scientists, the multiverse is the only way we will ever truly make sense of the world we are in. Do multiple universes exist? And if so, which one are we actually in?" Imagine a world where dinosaurs still walk the earth. A world where the Germans won World War II and you are president of the United States. Imagine a world where the laws of physics no longer apply.

Professor Jim Al-Khalili investigates the most accurate and yet perplexing scientific theory ever - quantum physics. At the beginning of the 20th century scientists were led into the hidden workings of matter, into the sub-atomic building blocks of the world around us. They discovered phenomena unlike any encountered before - a realm where things can be in many places at once, where chance and probability call the shots and where reality appears to only truly exist when we observe it. Albert Einstein hated the idea that nature, at its most fundamental level, is governed by chance. Jim reveals how, in the 1930s, Einstein thought he'd found a fatal flaw in quantum physics because it implies that sub-atomic particles can communicate faster than light in defiance of the theory of relativity. In the 1960s the scientist John Bell showed there was a way to test if Einstein was right and quantum mechanics was actually mistaken. Jim repeats this critical experiment - with shocking results.

Professor of physics Jim Al-Khalili investigates the most accurate and yet perplexing scientific theory ever - quantum physics, the perplexing theory of sub-atomic particles. Turning his attention to the world of nature, can quantum mechanics explain the greatest mysteries in biology? The European robin navigates using one of the most bizarre effects in physics - quantum entanglement, a process which seems to defy common sense. Jim finds that even the most personal of human experiences - our sense of smell - is touched by ethereal quantum vibrations. According to new experiments it seems that our quantum noses are listening to smells. Jim discovers that the most famous law of quantum physics - the uncertainty principle - is obeyed by plants and trees as they capture sunlight during the vital process of photosynthesis. Jim wonders if the strange laws of the sub-atomic world, which allow objects to tunnel through impassable barriers in defiance of common sense, could effect the mechanism by which living species evolve?

The Spirit Molecule investigates dimethyltryptamine (DMT), a naturally occurring psychoactive compound, which exists in humans, and potentially every living organism. Utilizing Dr. Rick Strassman's government-sanctioned, human DMT research as the documentary's backbone, the study's potential impact and its inconceivable revelations emerge. A closer examination of DMT's effects through two traditionally opposed concepts, science and spirituality, The Spirit Molecule unravels the connections between cutting-edge neuroscience, quantum mechanics and human spirituality.
The Spirit Molecule, a simple molecule with enormous implications. The subtle combination of science, spirituality, and philosophy results in an abundance of incredible ideas and theories that could alter the way we understand the nature of reality and our relationship to it.

Author and nuclear physicist Professor Jim Al-Khalili looks at what led to the discovery that everything is made of atoms. The programme looks at how the discovery affected the scientific world including the atomic energy theories of Albert Einstein and Werner Heisenberg and quantum mechanics

In the last in the series Professor Jim Al-Khalili explores how studying the atom forced us to rethink the nature of reality itself. He discovers that there might be parallel universes in which different versions of us exist, finds out that empty space isn't empty at all, and investigates the differences in our perception of the world in the universe and the reality.