Time and Your Brain (12 weeks)
W 2019

Description

What is time itself?  Is it possible to answer that question without considering the human brain?  Think about it.  To every person alive, time seems to flow continuously.  The present is what we see in front of us.  Or we think we see it, because our brain preprocesses every sensory input before we consciously apprehend it.  And what exactly is consciousness?

We will explore what modern neuroscience has to say about how time works inside your brain, and what modern physics can--and cannot--tell us about what time, itself, is.  This is a fascinating subject with plenty to explore and discuss, as you can see below from the topics we will cover.

Our core book was written for general readers; its explanations are clear, complete, and nonmathematical*.  We will follow it closely.  For anyone who wishes to dig deeper, it includes notes and extensive references.  

*Well, there's one equation, but there are plenty of sketches.

Weekly Topics

  1. Overviews:  Space, time, neuroscience, "presentism" vs. "eternalism", multiple meanings of time.
  2. How human brains are time machines:  Prediction, time computation, sensing of the flow of time, mental time travel, understanding cause & effect.  How neurons & synapses work, neural timing from microseconds to many seconds.
  3. Circadian clocks:  Mammalian clocks, clocks without night and day, brain clock location, clocks in plants, clocks in bacteria, clocks in other single cells, jet lag, human "morning larks" and "night owls", multiple clocks for different time scales.
  4. Subjective time:  Why prospective and retrospective time estimates differ, time compression, time dilation, time illusions, drug effects, alternative explanations of subjective-time phenomena.
  5. Patterns in time:  Speech phonetic timing, speech prosodic timing, "motherese", Morse code, interval timing experiments, why humans perceive musical beats but monkeys don't, songbird learning and production. Neuroscience timing studies in mouse and human brains.
  6. How brains measure "fast" time (milliseconds to seconds):  How one interval-tuned neuron times one event, how a large network of neurons can time multiple events at multiple intervals.  Timing patterns discovered by neuroscience. Simulations and recent results.
  7. The history and physics of time measurement:  Radiodating of prehistory using decaying atoms, development of calendars, development of mechanical clocks, development of resonant clocks (quartz-crystal electronic clocks and cesium atomic clocks), GPS.  How accurately can humans measure time?
  8. What is time itself?  Presentism and eternalism revisited, the "block universe", why physics doesn't explain the direction ("arrow") of time. How the Second Law of Thermodynamics and the concept of entropy try to explain the direction of time; the problem with that at the start of time.  The lack of answers about time from quantum mechanics.  What do we really know?
  9. Einstein's Special Relativity:  Does it specify the direction of time?  Special Relativity in English--time slows if you go really fast, simultaneity depends on your speed and where you stand.  A 4-dimensional-spacetime eternalist universe seems to fit Special Relativity, but a conflict remains between eternalism and the human perception of presentism.  Could "the flow of time" be a brain illusion?
  10. The spatialization of time in neuroscience:  Children understand time by first understanding space and speed; language uses spatial and flow terms to talk about time; human judgments of the time between events varies with the distance between them.
  11. Mental time travel:  Mentally re-experiencing life episodes and projecting oneself forward in time is a unique human cognitive ability and is the basis of human culture.  It is enabled by human brain size (measured relative to animals' sizes) and the human prefrontal cortex.
  12. Consciousness:  Perception vs. physical reality--perceived color vs. rainbow color.  What we don't see as it physically is.  We see and hear ocean waves crashing simultaneously though our eyes and ears deliver their perceptions milliseconds apart in time.  Some  observations of neuroscientists.  Since neuroscientists can know a decision by measuring a human's unconscious neuron signals before he or she implements the decision, does that mean that humans have no free will?  Additional views on consciousness.

Bibliography

Core Book: 

Dean Buonomano, Your Brain is a Time Machine: The Neuroscience and Physics of Time. Norton, 2017 (paperback).

Handout:

Susan Blackmore, "Decoding the Puzzle of Consciousness", Scientific American, September 2018, pp.49-53.