Ep 33. Do the Past and Future Exist?

PBS Space Time is an American science web series produced by PBS Digital Studios and written and hosted by astrophysicist Matt O'Dowd. In its 2020 season, the show delves deep into the mysteries of the universe, exploring topics ranging from the origins of the universe to the nature of space and time.

In episode 33 of the 2020 season, titled "Do the Past and Future Exist?", O'Dowd takes on one of the most fundamental questions in physics and philosophy - whether the past and future truly exist.

The episode begins with a brief introduction to the concept of time, from the ancient Greek philosopher Aristotle to the theories of modern physics. O'Dowd explains that while time seems like a simple concept, it is actually incredibly complex and mysterious.

He then introduces the concept of "block time", a model of the universe in which the past, present, and future all exist simultaneously as a single four-dimensional block. This model is supported by the theories of relativity, which suggest that time is not an absolute, but rather a relative concept that depends on the observer's point of view.

O'Dowd goes on to explore some of the philosophical implications of the block time model. If the past and future truly exist, does that mean that free will is an illusion, and that everything is predetermined? Or can we still make choices that shape our future, even if that future already exists?

He then discusses the concept of "presentism", the view that only the present moment truly exists, and that the past and future are nothing more than abstract concepts. This view is supported by some philosophers but is at odds with the theories of relativity.

O'Dowd then takes a closer look at the idea of causality, the belief that events in the present are caused by events in the past. He explains that while causality seems to be a fundamental feature of the universe, it is actually quite mysterious and difficult to explain.

He concludes the episode by exploring some of the current debates and research in the field of physics and philosophy. While the question of whether the past and future truly exist may never be fully answered, the journey of exploring this question is sure to lead to fascinating discoveries and insights into the nature of time and the universe.

Overall, "Do the Past and Future Exist?" is a thought-provoking and engaging episode that explores one of the most fundamental questions in science and philosophy. Whether you're a seasoned physicist or simply curious about the mysteries of the universe, this episode is sure to provide plenty of food for thought.