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Kindle Notes & Highlights
by
Max Tegmark
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December 4, 2024 - August 18, 2025
how does a brain attend to, interpret and respond to sensory input?
From my perspective, a conscious person is simply food, rearranged.
qualia,
Scott Aaronson,
“pretty hard problem” (PHP),
“even harder probl...
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“really hard proble...
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Karl Popper popularized the now widely accepted adage “If it’s not falsifiable, it’s not scientific.”
science is all about testing theories against observations: if a theory can’t be tested even in principle, then it’s logically impossible to ever falsify it, which by Popper’s definition means that it’s unscientific.
eponymous
“image classification”
“speech synthesis.”
behavioral correlates of consciousness,
the roughly 107 bits of information that enter our brain each second from our sensory organs, we can be aware only of a tiny fraction, with estimates ranging from 10 to 50 bits.
conscious information processing should be thought of as the CEO of our mind, dealing with only the most important decisions requiring complex analysis of data
Wilder Penfield
the somatosensory cortex
the motor cortex.
ECoG (electrocorticography)
animals with transparent brains—such as the C. elegans worm with its 302 neurons and the larval zebrafish with its about 100,000.
recent research suggests that the primary visual cortex is completely unconscious, together with the cerebellum and brainstem.
Christof Koch
“neural correlates of consciousness” (NCCs),
Do you see two women or a vase? If you look long enough, you’ll subjectively experience both in succession, even though the information reaching your retina remains the same. By measuring what happens in your brain during the two situations, one can tease apart what makes the difference—and
“continuous flash suppression”
if you make one of your eyes watch a complicated sequence of rapidly changing patterns, then this will distract your visual system to such an extent that you’ll be completely unaware of a still image shown to the other eye.
In summary, you can have a visual image in your retina without experiencing it, and you can (while dreaming) experience an image without it being on your retina. This proves that your two retinas don’t host you...
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your consciousness mainly resides in a “hot zone” involving the thalamus (near the middle of your brain) and the rear part of the cortex
the primary visual cortex at the very back of the head is an exception to this, being as unconscious as your eyeballs and your retinas.
it takes about a quarter of a second from when light enters your eye from a complex object until you consciously perceive seeing it
your consiousness lives in the past, with Christof Koch estimating that it lags behind the outside world by about a quarter second.
Intriguingly, you can often react to things faster than you can become conscious of them, which proves that the information processing in charge of your most rapid reactions must be unconscious.
For example, if a foreign object approaches your eye, your blink reflex can close your eyelid wit...
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it takes longer for you to analyze images than sounds because it’s more complicated—which is why Olympic races are started with a bang rather than with a visual cue.
PCCs: physical correlates of consciousness,
Giulio Tononi
If the future state of each part depends only on its own past, not on what the other part has been doing, then Φ = 0: what we called one system is really two independent systems that don’t communicate with each other at all.
Giulio had developed the most mathematically precise consciousness theory to date, integrated information theory (IIT).
the conscious system needs to be integrated into a unified whole, because if it instead consisted of two independent parts, then they’d feel like two separate conscious entities rather than one.
if a conscious part of a brain or computer can’t communicate with the rest, then the rest can’t be part of its subjective experience.
computronium,
blob
under what conditions will a blob of matter be able to do these four things? 1. remember 2. compute 3. learn 4. experience
sentronium
the most general substance that has subjective experience (is sentient).*5
summary, I think that consciousness is a physical phenomenon that feels non-physical because it’s like waves and computations: it has properties independent of its specific physical substrate.
consciousness, but here are four necessary conditions
Clive Wearing,
Scott Aaronson
Murray Shanahan
