The Physics of Time

Time is seen as part of the fundamental grammar of the world. Yet there is little evidence proving it actually exists. With the help of quantum physicist Carlo Rovelli, this episode seeks to mop up some of the biggest misconceptions surrounding time — exploring the theories and hypotheses shaping our current scientific understanding of it.

This episode in brief

1. Absolute Newtonian time | 03:00

We often think of time as a substance that lives outside of us and flows from past to future. But while useful, there is no strong scientific evidence showing this physical view of time is actually true. This section considers the origins of a universal “true time”, popularized by Isaac Newton, and the enduring impact it has had on the concept of time.

2. The challenge of Einstein’s relativity | 05:20

Einstein’s theories of relativity completely reimagined physical time, ushering a whole new level of existentialism into the theory of time. This chapter highlights some of his biggest points — like the illusion of universal clock time and simultaneity, and the idea of a 4D block universe which fixes all events ever to occur in time.

3. Directional time and entropy | 10:40

We consider time to be a fundamental part of our universe, but there is in fact only one natural law suggesting it exists and has a direction. This section lays out the idea of entropy — the tendency towards disorder within nature — as possible proof for “moving” time, as well as its limitations. It acknowledges how even objective scientific laws are subject to intrusions by our own subjective human perspective.

4. The quantum perspective with Carlo Rovelli | 14:00

When we study the smallest physical quantities of the universe, our popular notions of time quickly lose meaning. Drawing from his latest book, The Order of Time, world-renown physicist Carlo Rovelli proposes a new model for thinking about time. He explains why the answer to time’s mystery arguably has as much to do with how humans work as with the manner of the cosmos.