The Physics of Time

07/23/19 • 21 min

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.

This episode in brief
1. Absolute Newtonian time | 03:00

Previous Episode

The Language of Time

“Time” is the most frequently used noun in the English language. But what are we actually talking about when we talk about time? This episode looks at time representations and referencing systems used by different cultures, to explore how far language can shape how we think about time.
This episode in brief:
1.The spatial language of time | 03:45

Many cultures use the graphical model of space to understand time, but there are some pretty interesting differences in how the world’s languages conceptualize time. This section explores examples from Western European and Scandinavian languages to Mandarin Chinese, Aymara, and the aboriginal language of the Pormpuraaw community in Australia.
2. Event-based time | 13:10

While countable “clock time” seems like second-nature for the West, in some cultures it doesn’t exist. Starting with the Amazonian Amondawa community, this section considers languages who use events to index and talk about time. Anthropologist Vera da Silva Sinha draws insights from her latest research on three Brazilian tribes — the Huni Kuĩ, Awetý and Kamaiurá — who don’t count age, celebrate birthdays or use spatial metaphors to speak about time.
3. Languages without tense | 21:55

English – like most European languages – is a tensed language. But many languages do not use tense at all. This section explores how “tenseless” languages like Mandarin Chinese use aspect to indicate time, as well as the conceptual limitations our own three-tensed grammar imposes on how we communicate time.

Next Episode

The Psychology of Time

Since we can’t prove that time physically exists, it must live somewhere inside the human mind. With the help of neuropsychologist Marc Wittmann, this episode takes a closer look at subjective time — the time we ‘feel’ — to see how our brains create our sense of time, and why it’s constantly speeding up and slowing down.
This episode in brief
1. How we are able to perceive time | 02:30

Time processing plays a role in almost all aspects of our cognitive function. But what exactly is happening in our brain? This episode introduces the core mechanism of time perception, from the 3-second perceptual moment, to the combined role of memory, attention and anticipation. We see that our brain is constantly throwing out predictions based on previous experience and testing them against new information in our environment.

2. How the brain keeps time | 08:45

Even though we can’t see, touch or hear time, our brains can still track its passage. We know what minutes and hour feel like, even when sat in a windowless meeting room. But how do we do this? This section explores some of the theories around how and where the brain predicts duration — both when consciously paying attention to time passing, or reconstructing a sense of it after the fact.
3. Why does time speed up and slow down? | 12:50

Unlike clock time, the time you directly experience isn’t steady and constant. It’s continually speeding up and slowing down, and as we age time seems to get faster. But what causes this flux? With the help of neuropsychologist Marc Wittmann, we explore how memory density, novelty, signpost events, attention to time, drugs affecting dopamine and emotional states all impact our perception of time. We see that perceiving time in so many ways is not a design flaw, but an essential part of our humanity.