This episode explores the wave theory of light as studied by mankind, noting that light has played an important role in scientific progress, with such early experiments from over 2000 years ago involving the camera obscura by the Chinese philosopher Mozi. Tyson describes the work of the 11th century Arabic scientist Ibn al-Haytham, considered to be one of the first to postulate on the nature of light and optics leading to the concept of the telescope, as well as one of the first researchers to use the scientific method. Tyson proceeds to discuss the nature of light as discovered by mankind. Work by Isaac Newton using diffraction through prisms demonstrated that light was composed of the visible spectrum, while findings of William Herschel in the 19th century showed that light also consisted of infrared rays. Joseph von Fraunhofer would later come to discover that by magnifying the spectrum of visible light, gaps in the spectrum would be observed. These Fraunhofer lines would later be determined to be caused by the absorption of light by electrons in moving between atomic orbitals when it passed through atoms, with each atom having a characteristic signature due to the quantum nature of these orbitals. This since has led to the core of astronomical spectroscopy, allowing astronomers to make observations about the composition of stars, planets, and other stellar features through the spectral lines, as well as observing the motion and expansion of the universe, and the existence of dark matter.

An epic documentary film in which nine scientists will meet in a chain of encounters to uncover unexpected answers to some of humanity's biggest questions. How did life begin? What is time? What is consciousness? How much do we really know? By introducing researchers from diverse backgrounds for the first time, then dropping them into new, immersive field work they previously hadn't tackled, the film reveals the true potential of interdisciplinary collaboration, pushing the boundaries of how science storytelling is approached.
What emerges is a deeply human trip to the foundations of discovery and a powerful reminder that the unanswered questions are the most crucial ones to pose. The Most Unknown is an ambitious look at a side of science.

Professor Brian Cox journeys across the vastness of time and space revealing epic moments of sheer drama that changed the universe forever.
The series begins this epic exploration of the cosmos with a hymn to the great luminous bodies that bring light and warmth to the universe: the stars. It is estimated that there are two hundred trillion stars in the universe, each playing their part in an epic story of creation- a great saga that stretches from the dawn of time, with the arrival of the first star, through diverse generations until the arrival of our own star, the sun, and a civilization that has grown up in its light.

Tyson describes the discovery of cosmic rays by Victor Hess through high-altitude balloon trips. Swiss Astronomer Fritz Zwicky, in studying supernovae, postulated that these cosmic rays originated from these events instead of electromagnetic radiation. Also tells how Vera Rubin observed that the rotation of stars at the edges of observable galaxies did not follow expected rotational behavior leading to consider the existence of dark matter. This further led to the discovery of dark energy to account for the increasing rate of expansion of the universe. Tyson then describes the interstellar travel of the two Voyager probes. Tyson tells the Carl Sagan's role in the Voyager program, including creating the Voyager Golden Record to encapsulate humanity and Earth's position in the universe. Tyson concludes the series by emphasizing Sagan's message on the human condition in the vastness of the cosmos, and to encourage viewers to continue to explore and discover what else the universe has to offer.

In the concluding episode of the series, Jim encounters ever larger cosmic structures to reveal the latest breakthroughs in our understanding of the universe. For example, Jim comes face to face with our galactic home, the Milky Way, a monstrous structure sculpted by the gravitational forces of dark matter. Jim finds out from pioneering researcher Adrian Fabian about the black hole at its centre, whose strange behaviour includes emitting the lowest note that can be heard in the cosmos.
At an even greater scale, Jim encounters huge structures such as the Laniakea Supercluster, of which the Milky Way is only a tiny part. Then there’s the 'Giant Arc', a collection of galaxies that account for more than three per cent of the observable universe. Jim learns from its discoverer, British PhD student Alexia Lopez, that this gargantuan structure is forcing scientists to reassess their theory of how the universe evolves and may overturn some of the most fundamental principles in physics.

The film brings viewers all the amazing news-breaking advances in science in technology from 2021, unfolding around the globe. Shattering barriers and questioning assumptions and turning ideas on their head. Stories that take a leap into the future or follow footprints to the past.
Startling discoveries from a prehistoric nursery to a magic bullet that could contain the pandemic. Accomplishments like harnessing a star in a bottle or mapping invisible parts of the universe. Join us for an exclusive hyper-tour from earth to space.