Your Brain is a Time Machine, with Dean Buonomano

Unlike man-made clocks that rely on counting regular oscillations (like a pendulum or quartz crystal), the brain tells time through complex neural dynamics. It's more akin to an hourglass, where the 'falling' patterns of activity across neurons represent the passage of time. Different brain clocks are responsible for different timescales (e.g., microseconds for auditory localization, circadian rhythms for daily cycles), unlike a single wrist watch.

Dean states, 'The brain does not work like that... they don't rely on an oscillator. They rely on dynamics... the brain is the most complex dynamical system we know of. And it has these patterns of activity. And these patterns of activity are what we use to tell time.' He also notes, 'The clocks in our brain that are responsible for seconds, they don't have an hour hand. And the circadian clock doesn't have a second hand.'

The human ability for 'mental time travel'—projecting into the past or future—is a defining cognitive trait. This capacity was crucial for major evolutionary leaps, such as the invention of agriculture (planting now for future benefits) and the profound awareness of death. This awareness, in turn, may have co-evolved with religion as an 'antidote' to mortality.

Dean explains, 'One thing that distinguishes us from most other animals is our ability to engage in what we'll call mental time travel... You think of something as fundamental as the invention of agriculture. Plant a seed, reap the benefits later. That was a very hard step for us to connect the temporal dots over weeks, months, and years.' He adds, 'Can you imagine what it was like for the first human to make this cognitive leap and say, 'Oh, I'm going to die.'... It's ability to engage in mental time travel that we became aware of death.'

Buonomano argues for 'presentism,' the view that only the present is real and time genuinely flows, in contrast to 'eternalism' (or the block universe) where past, present, and future are equally real, a common interpretation in physics. He posits that the brain's perception of time's flow is not merely an illusion but reflects a true aspect of the physical universe, specifically at the 'mesoscopic' scale where humans evolved to survive.

Dean states, 'Many physicists would argue that the perception of time, the flow of time... is an illusion or a mental construct... This is the debate between what we call eternalism or the block universe and presentism.' He counters, 'I've argued and that I think the brain is telling us something true about the physical universe, that it is because we evolved to survive in a universe governed by the laws of physics, in a mesoscopic part of that universe... it is really flowing and our brain creates this conscious perception of the flow because it's a real part of what we experience, end of the universe.'

The idea of 'uploading' complex skills or memories directly into the brain via interfaces (like those depicted in Total Recall or Neuralink's potential applications) is met with skepticism. This is because the brain's architecture differs fundamentally from a computer's; memory and computation are deeply intertwined, not separated like a CPU and RAM. Direct 'uploading' would require a radical modification of how brains work.

Dean states, 'I think a lot of that relies on sort of a simplistic understanding of the brain as a computer... In the brain, that distinction [between memory and computation] doesn't make as much sense because it's the activity flowing through these networks that is both the computation and the memory.' He adds, 'I'm very skeptical of those notions, because I think they don't really capture how the brain actually works.'