PBS Space Time Season 2019 Episode 31 How Many Universes Are There?

In this episode of PBS Space Time, titled "How Many Universes Are There?" the hosts delve into the concept of multiple universes. With the help of guest astrophysicist Dr. Avi Loeb, they explore the theories behind the multiverse hypothesis and discuss the evidence that supports it.

The episode begins by explaining that the idea of multiple universes is not a new one, but has been a topic of debate among scientific and philosophical circles for centuries. The hosts then dive into the various interpretations of the multiverse, including the Level 1 multiverse which proposes an infinite number of universes with the same physical laws and constants as our own.

As the discussion continues, the hosts explore the idea of a Level 2 multiverse, which suggests that there may be universes with different physical laws and constants than our own. They explain that such universes could exist within the same physical space as our own, but that we are simply unable to observe them due to the limitations of our technology.

The conversation then shifts to the concept of a Level 3 multiverse, which proposes that there may be an infinite number of universes with different initial conditions. This means that each universe would have a unique set of physical laws, constants, and initial configurations. The implications of such a multiverse are vast and would require a re-evaluation of our current understanding of physics.

Throughout the episode, Dr. Loeb provides insights into some of the recent discoveries that support various multiverse theories. He explains that one possible way to detect the existence of other universes would be through the study of cosmic microwave background radiation. By mapping the variations in the radiation across the universe, scientists may be able to detect the presence of other universes which would manifest as anomalies in the data.

The hosts also discuss the controversial idea of the anthropic principle, which suggests that the reason we observe our universe to have the physical laws and constants we do is because they allow for the existence of life. Some scientists argue that this is evidence of a designer or creator who intentionally created a universe capable of sustaining life, while others see it as a natural consequence of the multiverse hypothesis.

As the episode draws to a close, the hosts delve into the philosophical implications of the multiverse, including the possibility of multiple versions of ourselves existing in different universes. They emphasize that while the idea of multiple universes may seem far-fetched, it is rooted in solid scientific theory and has the potential to revolutionize our understanding of the universe.

Overall, "How Many Universes Are There?" provides a fascinating glimpse into one of the biggest mysteries in modern physics. Through a combination of expert guest insights and clear explanations, the episode offers a compelling argument for the existence of multiple universes and the potential implications of this groundbreaking theoretical concept.