StarTalk Radio

Your Brain is a Time Machine with Dean Buonomano

January 9, 2026

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  • Unlike man-made clocks that rely on counting regular oscillations, the brain tells time across different scales (seconds to circadian rhythms) using complex neural dynamics, which are more analogous to an hourglass. 
  • The human ability for mental time travel—remembering the past and projecting the future—is a sophisticated cognitive function that distinguishes us from most other animals and is deeply linked to our awareness of mortality. 
  • In neuroscience, memory and computation are inseparable because information is stored by changing the strength of connections between neurons, contrasting with the distinct memory and processing modules found in standard computer architecture. 

Segments

Introduction and Episode Tease
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(00:01:06)
  • Key Takeaway: The episode will explore whether time is an illusion by examining how the brain remembers the past and projects the future.
  • Summary: The episode of StarTalk Radio, ‘Your Brain is a Time Machine with Dean Buonomano,’ sets out to investigate the nature of time, contrasting physics’ view with our subjective experience in the brain. The central question posed is whether time travel is possible only within the human mind. The discussion will cover how we tell time, why we need to, and the possibility of mental time travel.
Guest and Book Introduction
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(00:02:57)
  • Key Takeaway: Dean Buonomano, Professor of Neurobiology and Psychology at UCLA, authored ‘Your Brain is a Time Machine, the Neuroscience and Physics of Time.’
  • Summary: The guest is introduced as Dean Buonomano, a professor at UCLA specializing in neurobiology and psychology. His book, ‘Your Brain is a Time Machine, the Neuroscience and Physics of Time,’ is the focus of the discussion. The hosts briefly joke about the Italian meaning of his surname, ‘Buonomano.’
How the Brain Tells Time
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(00:04:23)
  • Key Takeaway: The brain’s timing mechanisms differ fundamentally from man-made clocks, relying on dynamics and patterns of activity rather than simple, repeating oscillators.
  • Summary: Man-made clocks rely on counting regular oscillations of a time base, like a pendulum or quartz crystal, and can measure vast scales of time with one device. The brain, however, uses different, specialized ‘clocks’ for different scales, such as those for seconds versus the circadian rhythm. These neural clocks often rely on the dynamics of complex systems, similar to an hourglass, rather than a fixed oscillator.
Circadian Rhythms and Entrainment
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(00:07:48)
  • Key Takeaway: The master circadian clock resides in the suprachiasmatic nucleus and is entrained by visual input to match the Earth’s 24-hour rotation.
  • Summary: The circadian clock is based on a biomolecular mechanism involving a transcription-translation autoregulatory feedback loop, resulting in an oscillation that approximates 24 hours. This clock is located in the suprachiasmatic nucleus, which is associated with vision because light input is used to ’entrain’ or synchronize the internal rhythm to the external day/night cycle. Organisms, including cyanobacteria, need this timing ability to anticipate environmental changes, such as the rising of the sun for photosynthesis.
Evolutionary Need for Timing
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(00:12:42)
  • Key Takeaway: The human need to tell time evolved because anticipating future events is crucial for survival, cooperation, and social synchronization.
  • Summary: The ability to anticipate what will happen is vital for interacting with others, catching prey, or avoiding predators. The development of cheap clocks was a key engine of the Industrial Revolution because factories required synchronizing human behavior. Cooperation inherently requires timing, as evidenced by people naturally synchronizing movements like clapping at events.
Neural Basis of Timing and Memory
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(00:19:43)
  • Key Takeaway: The brain’s perception of time flow, which implies an arrow of time, is a conscious construct that contrasts with physics interpretations suggesting past, present, and future are equally real (eternalism).
  • Summary: The brain processes sensory information, like sight and sound, within a temporal window of integration (around 200-400 milliseconds), which it adaptively fixes to align space and time, as seen in the McGurk illusion. Memory storage involves changing the strength of connections between neurons, where computation and memory are intertwined, unlike in a von Neumann computer architecture. The timing of sequences, like in Morse code or language, relies on neural dynamics forming trajectories in neural space rather than simple oscillations.
Time in Physics vs. Neuroscience
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(00:35:42)
  • Key Takeaway: Neuroscience is currently maturing to address time, similar to how geometry evolved into dynamics by incorporating time over 2,000 years after its inception.
  • Summary: Time is considered a central, complex problem linking free will, consciousness, and the nature of reality, arguably more complicated than space. Early science, like geometry, was timeless and static, requiring the work of Galileo and Newton to add dynamics (time) to space. Neuroscience is now reaching a stage where it must incorporate time to fully understand the brain, constrained by cognitive limitations that mathematics helps model.
Mental Time Travel and Future Tech
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(00:44:28)
  • Key Takeaway: The brain’s organic, non-von Neumann structure makes uploading skills like Mandarin or Kung Fu via brain-computer interfaces highly improbable based on current neuroscience.
  • Summary: The ability to engage in mental time travel, such as planning for agriculture, is a sophisticated cognitive leap that allowed humans to become aware of death. Portrayals in films like ‘Total Recall’ or by companies like Neuralink often rely on a simplistic view of the brain as a computer with separable memory and CPU modules. Because computation and memory are integrated in the brain’s dynamics, dramatically enhancing bandwidth through electrode implantation is unlikely to result in instant skill acquisition.
Conclusion on Time Travel Possibility
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(00:47:12)
  • Key Takeaway: The human brain’s mental time travel is likely the closest physics will allow to a time machine, as physical time travel is theoretically impossible according to presentist views.
  • Summary: From a presentist perspective, physical time travel, even through theoretical constructs like wormholes, is considered impossible. Stephen Hawking supported this view with his time travel prevention conjecture, suggesting a future law of physics will forbid it to prevent paradoxes. The brain’s capacity to mentally revisit the past and project the future remains the most advanced form of time manipulation available.