This episodes the nature of the cosmos on the micro and atomic scales, using the Ship of the Imagination to explore these realms. Tyson describes some of the micro-organism that live within a dew drop, demonstrating parameciums and tardigrades. He proceeds to discuss how plants use photosynthesis via their chloroplasts to convert sunlight into chemical reactions that convert carbon dioxide and water into oxygen and energy-rich sugars. Tyson then discusses the nature of molecules and atoms and how they relate to the evolution of species. He uses the example set forth by Charles Darwin postulating the existence of the long-tongued Morgan's sphinx moth based on the nature of the comet orchid with pollen far within the flower. He further demonstrates that scents from flowers are used to trigger olfactory centers in the brain, stimulating the mind to threats as to aid in the survival of the species. Tyson narrates how Greek philosophers Thales and Democritus postulated that all matter was made up of combinations of atoms in a large number of configurations, and describes how carbon forms the basic building block for life on earth due to its unique chemical nature. Tyson explains on the basic atomic structure of protons, neutrons, and electrons, and the nature of nuclear fusion that occurs in most stars. He then discusses the existence of neutrinos that are created by these nuclear processes in stars, and that detecting such sub-atomic particles which normally pass through matter require subterranean facilities like the Super-Kamiokande that were used to detect neutrinos from the supernova SN 1987A in the Large Magellanic Cloud before light from the explosion were observed due to their ability to pass through matter of the dying sun. Tyson compares how neutrinos were postulated by Wolfgang Pauli to account for the conservation of energy from nuclear reactions in the same manner as Darwin's postulate on the long-tongued moth. Tyson concludes by noting that there are neutrinos from the Big Bang still existing in the universe but due to the nature of light, there is a "wall of infinity" that cannot be observed beyond.

P.U.L.S.E is a Pink Floyd concert video taken from the 20 October 1994 concert at Earls Court, London. PULSE records the great psychedelic band Pink Floyd rocking out like only they can. Renowned for their hallucinatory special effects and lighting schemes, Pink Floyd goes all out at this spectacular (and very long) concert. Twenty-one of their classics are performed, including classic rock radio staples 'Dark Side of The Moon' and 'Wish You were Here". There was considerable delay in the release of the video edition of Pulse. The cause of the delays was reputed to be the continued modifications and additions to produce a high-quality release. The previous planned release date of 22 September 2005 for the two-disc DVD set was changed to 10 July 2006 for the UK and Europe, and 11 July 2006 everywhere else.

Prepare yourself for an unparalleled sensory experience. Samsara reunites director Ron Fricke and producer Mark Magidson, whose award-winning films Baraka and Chronos were acclaimed for combining visual and musical artistry. Samsara explores the wonders of our world from the mundane to the miraculous, looking into the unfathomable reaches of humanity's spirituality and the human experience. Neither a traditional documentary nor a travelogue, Samsara takes the form of a nonverbal, guided meditation.

Fourth episode examines how plants either share environments harmoniously or compete for dominance within them. Attenborough highlights the 1987 hurricane and the devastation it caused. However, for some species, it was that opportunity for which they had lain dormant for many years. The space left by uprooted trees is soon filled by others who move relatively swiftly towards the light. The oak is one of the strongest and longest-lived, and other, lesser plants nearby must wait until the spring to flourish before the light above is extinguished by leaves. Tropical forests are green throughout the year, so brute force is needed for a successful climb to the top of the canopy: the rattan is an example that has the longest stem of any plant. As its name suggests, the strangler fig 'throttles' its host by growing around it and cutting off essential water and light. Some can take advantage of a fallen tree by setting down roots on the now horizontal trunk and getting nutriment from the surrounding moss and the fungi on the dead bark. The mountain ash (eucalyptus regnans) grows so tall, that regeneration becomes a considerable problem. It is easily flammable, so its solution is to shed its seeds during a forest fire and sacrifice itself. It therefore relies on the periodic near-destruction of its surroundings in order to survive. Attenborough observes that catastrophes such as fire and drought, while initially detrimental to wildlife, eventually allow for deserted habitats to be reborn.

Mountain biking requires endurance, core strength and balance, bike handling skills, and self-reliance. Advanced riders pursue both steep technical descents and high incline climbs. In the case of freeriding, down hilling, and dirt jumping, aerial manoeuvres are performed off both natural features and specially constructed jumps and ramps. Follows several individuals breaking out of their mundane lives and entering into the adventurous thrill-seeking world of this sport.

The State Hermitage Museum in St Petersburg is one of the largest and most visited museums in the world. Margy Kinmonth's film tells the story of its journey from imperial palace to state museum, investigating remarkable tales of dedication, devotion, ownership and ultimate sacrifice, showing how the collection came about, how it survived tumultuous revolutionary times and what makes the Hermitage unique today. Holding over three million objects and boasting more curators than any other museum, the Hermitage's story is Russia's history in microcosm and its art has lived to tell the tale