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uncategorized:ai_safety_arguments_affected_by_chaos:chaos_in_humans [2023/04/05 21:40]
jeffreyheninger |
uncategorized:ai_safety_arguments_affected_by_chaos:chaos_in_humans [2023/04/07 20:48] (current)
jeffreyheninger |
| There are various scales on which humans might be chaotic. At the largest scales, are human societies chaotic? At the human scale, how chaotic or predictable is an individual’s behavior? At the organ scale, how chaotic is the human brain? Other organs might also exhibit chaos, but it seems less likely that chaos in the endocrine system, for example, would be as important for understanding human behavior as chaos in the brain. At the cellular scale, do individual neurons behave chaotically? At the atomic and molecular scales, thermal noise and quantum effects dominate. This is not classical chaos, but it does provide the microscopic uncertainty that might be amplified by the chaos at larger scales. | There are various scales on which humans might be chaotic. At the largest scales, are human societies chaotic? At the human scale, how chaotic or predictable is an individual’s behavior? At the organ scale, how chaotic is the human brain? Other organs might also exhibit chaos, but it seems less likely that chaos in the endocrine system, for example, would be as important for understanding human behavior as chaos in the brain. At the cellular scale, do individual neurons behave chaotically? At the atomic and molecular scales, thermal noise and quantum effects dominate. This is not classical chaos, but it does provide the microscopic uncertainty that might be amplified by the chaos at larger scales. |
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| It seems as though, at most scales, there can be either chaotic or non-chaotic behavior, and can transition between the two.((This is sometimes expressed as the Critical Brain Hypothesis: the brain, and many other biological systems, operate close to the transition between chaotic and non-chaotic motion. \\ Bak. //How Nature Works: The Science of Self-Organised Criticality.// (Copernicus Press, New York, 1996).)) This makes it difficult to determine if there is a continual chain of chaos from atomic to macroscopic scales. Even though this is hard to show, it seems likely that this would be true for at least some important sub-system of the brain in some circumstances. Chaos is a thing that a brain can do, even if not everything the brain does is chaotic. | It seems as though, at most scales, there can be either chaotic or non-chaotic behavior, and there can be transitions between the two.((This is sometimes expressed as the Critical Brain Hypothesis: the brain, and many other biological systems, operate close to the transition between chaotic and non-chaotic motion. \\ Bak. //How Nature Works: The Science of Self-Organised Criticality.// (Copernicus Press, New York, 1996).)) This makes it difficult to determine if there is a continual chain of chaos from atomic to macroscopic scales. Even though this is hard to show, it seems likely that this would be true for at least some important sub-system of the brain in some circumstances. Chaos is a thing that a brain can do, even if not everything the brain does is chaotic. |
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| Even if humans are not predictable, we might still be controllable. In order for you to control a chaotic system, it has to be possible to input a signal of the same sort as any of the sources of uncertainty that the chaos amplifies, and at a speed faster than the Lyapunov time. Whenever the trajectory starts to diverge from the path through the chaos you want it to follow, you have to input some signal to correct the path, before the divergence has gotten too large. | Even if humans are not predictable, we might still be controllable. In order for you to control a chaotic system, it has to be possible to input a signal of the same sort as any of the sources of uncertainty that the chaos amplifies, and at a speed faster than the Lyapunov time. Whenever the trajectory starts to diverge from the path through the chaos you want it to follow, you have to input some signal to correct the path, before the divergence has gotten too large. |
| Some bird species can sense the earth’s magnetic field and use it to navigate.((This is discussed some more in the blog post [[https://blog.aiimpacts.org/p/whole-bird-emulation-requires-quantum-mechanics|Whole Bird Emulation requires Quantum Mechanics]].)) The mechanism seems to involve quantum spin states of pairs of electrons.((Holland. //True navigation in birds: from quantum physics to global migration.// Journal of Zoology **293**. (2014) [[https://zslpublications.onlinelibrary.wiley.com/doi/pdfdirect/10.1111/jzo.12107]].)) In a bird’s retina, there are some pigments (cryptochromes) which absorb light and separate electrons into a radical pair. The spins of the electrons are initially pointing in opposite directions (in a singlet state), but an external magnetic field can flip them so they point in the same direction (in a triplet state). The decay products of the singlet and triplet are different. The retina can detect how the relative concentration of the decay products changes, allowing the bird to “see” the magnetic field. The energy difference between the two states is associated with a frequency of 1-100 MHz.(( One experiment found the response to be in a much narrower band from 1-3 MHz: \\ Ritz. //Quantum effects in biology: Bird navigation.// Procedia Chemistry **3**. (2011) [[https://www.sciencedirect.com/science/article/pii/S1876619611000738]].)) Exposing a bird (European robin) to a weak magnetic field oscillating at this frequency disorients it, so it is unable to navigate. This sense requires maintaining quantum coherence of the spins for at least 100 microseconds, longer than the best man-made spin states in similarly warm and wet environments.((Gauger et al. //Sustained quantum coherence and entanglement in the avian compass.// Physical Review Letters **106**. (2011) [[https://arxiv.org/pdf/0906.3725.pdf]].)) | Some bird species can sense the earth’s magnetic field and use it to navigate.((This is discussed some more in the blog post [[https://blog.aiimpacts.org/p/whole-bird-emulation-requires-quantum-mechanics|Whole Bird Emulation requires Quantum Mechanics]].)) The mechanism seems to involve quantum spin states of pairs of electrons.((Holland. //True navigation in birds: from quantum physics to global migration.// Journal of Zoology **293**. (2014) [[https://zslpublications.onlinelibrary.wiley.com/doi/pdfdirect/10.1111/jzo.12107]].)) In a bird’s retina, there are some pigments (cryptochromes) which absorb light and separate electrons into a radical pair. The spins of the electrons are initially pointing in opposite directions (in a singlet state), but an external magnetic field can flip them so they point in the same direction (in a triplet state). The decay products of the singlet and triplet are different. The retina can detect how the relative concentration of the decay products changes, allowing the bird to “see” the magnetic field. The energy difference between the two states is associated with a frequency of 1-100 MHz.(( One experiment found the response to be in a much narrower band from 1-3 MHz: \\ Ritz. //Quantum effects in biology: Bird navigation.// Procedia Chemistry **3**. (2011) [[https://www.sciencedirect.com/science/article/pii/S1876619611000738]].)) Exposing a bird (European robin) to a weak magnetic field oscillating at this frequency disorients it, so it is unable to navigate. This sense requires maintaining quantum coherence of the spins for at least 100 microseconds, longer than the best man-made spin states in similarly warm and wet environments.((Gauger et al. //Sustained quantum coherence and entanglement in the avian compass.// Physical Review Letters **106**. (2011) [[https://arxiv.org/pdf/0906.3725.pdf]].)) |
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| A few other biological quantum processes have been proposed, although they do not seem to have gained as broad of acceptance as these two. Electron transfer over tens of angstroms between redox centers in proteins might occur via tunneling,((Gray & Winkler. //Electron tunneling through proteins.// Quarterly Reviews of Biophysics **36.3**. (2003) [[https://web.archive.org/web/20050312141415id_/http://www.userwebs.pomona.edu:80/~ejc14747/Chem%20180/Gray_Winkler_QRB_et_proteins.pdf]].)) including possible interference between different paths.((Curry et al. //Pathways, Pathway Tubes, Pathway Docking, and Propagators in Electron Transfer Proteins.// Journal of Bioenergetics and Biomembranes **27.3**. (1995) [[http://www.cvri.ucsf.edu/~grabe/papers/Curry(1995).pdf]].)) Biological photoreceptors can be extremely sensitive to small amounts of light. Rods in human eyes respond to single photons,((Rieke & Baylor. //Single-photon detection by rod cells of the retina.// Reviews of Modern Physics **70.3**. (1998) [[https://www.cns.nyu.edu/csh/csh04/Articles/Rieke1998.pdf]].)) although the retina does not seem to send a single to the brain until close to 10 photons have been detected. The sense of smell might partially identify molecules by their vibrational modes excited by inelastic electron tunneling,((Turin. //A Spectroscopic Mechanism for Primary Olfactory Reception.// Chemical Senses **21.6**. (1996) p. 773-791. [[https://academic.oup.com/chemse/article/21/6/773/488342]].)) although this is disputed. | A few other biological quantum processes have been proposed, although they do not seem to have gained as broad of acceptance as these two. Electron transfer over tens of angstroms between redox centers in proteins might occur via tunneling,((Gray & Winkler. //Electron tunneling through proteins.// Quarterly Reviews of Biophysics **36.3**. (2003) [[https://web.archive.org/web/20050312141415id_/http://www.userwebs.pomona.edu:80/~ejc14747/Chem%20180/Gray_Winkler_QRB_et_proteins.pdf]].)) including possible interference between different paths.((Curry et al. //Pathways, Pathway Tubes, Pathway Docking, and Propagators in Electron Transfer Proteins.// Journal of Bioenergetics and Biomembranes **27.3**. (1995) [[http://www.cvri.ucsf.edu/~grabe/papers/Curry(1995).pdf]].)) Biological photoreceptors can be extremely sensitive to small amounts of light. Rods in human eyes respond to single photons,((Rieke & Baylor. //Single-photon detection by rod cells of the retina.// Reviews of Modern Physics **70.3**. (1998) [[https://www.cns.nyu.edu/csh/csh04/Articles/Rieke1998.pdf]].)) although the retina does not seem to send a signal to the brain until close to 10 photons have been detected. The sense of smell might partially identify molecules by their vibrational modes excited by inelastic electron tunneling,((Turin. //A Spectroscopic Mechanism for Primary Olfactory Reception.// Chemical Senses **21.6**. (1996) p. 773-791. [[https://academic.oup.com/chemse/article/21/6/773/488342]].)) although this is disputed. |
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| Biological settings are not places where you would expect quantum coherence to persist for very long. They have too high temperatures and lots of complex interactions. However, there are a few examples of quantum coherence persisting for much larger time or length scales than we would naively think is possible. Additionally, sensory organs can detect and respond to extremely small signals. | Biological settings are not places where you would expect quantum coherence to persist for very long. They have too high temperatures and lots of complex interactions. However, there are a few examples of quantum coherence persisting for much larger time or length scales than we would naively think is possible. Additionally, sensory organs can detect and respond to extremely small signals. |
| ==== Cells ==== | ==== Cells ==== |
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| Neurons are a type of cell in the brain which process information. Neurons are connected in large networks which act collectively to produce behavior. The way they are connected are through synapses, small junctions in between two neurons where neurotransmitters can be exchanged. | Neurons are a type of cell in the brain which process information. Neurons are connected in large networks which act collectively to produce behavior. The way they are connected is through synapses, small junctions in between two neurons where neurotransmitters can be exchanged. |
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| When neurotransmitters are released at synaptic junctions, they can bind to receptors embedded in the neuron's cell wall. If the receptors are activated by the neurotransmitters, they open and allow an influx of potassium and sodium ions (both positively charged) into the cell, which causes a spike in the neuron's internal voltage. If that voltage passes a threshold, an action potential is fired. An action potential then travels down the axon of a neuron, causing the synapses of that neuron to release neurotransmitters to the next neuron, and the cycle repeats (shown below). | When neurotransmitters are released at synaptic junctions, they can bind to receptors embedded in the neuron's cell wall. If the receptors are activated by the neurotransmitters, they open and allow an influx of potassium and sodium ions (both positively charged) into the cell, which causes a spike in the neuron's internal voltage. If that voltage passes a threshold, an action potential is fired. An action potential then travels down the axon of a neuron, causing the synapses of that neuron to release neurotransmitters to the next neuron, and the cycle repeats (shown below). |
| Two experiments stand out as particularly good examples of how chaos and transitions to and from chaos can play a role in the nervous system. | Two experiments stand out as particularly good examples of how chaos and transitions to and from chaos can play a role in the nervous system. |
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| When shown a flash of light, the neurons in a retina (of tiger salamander larvae or humans) exhibit a particular firing pattern, which stops shortly after the flash.((Crevier & Meister. //Synchronous Period-Doubling in Flicker of Salamander and Man.// Journal of Neurophysiology **79**. (1998) p. 1869-1878. [[https://journals.physiology.org/doi/pdf/10.1152/jn.1998.79.4.1869]].)) If the flash is shown periodically, with a frequency of less than 9 Hz, the retina’s response is periodic: each flash is followed by this particular firing pattern. When the frequency exceeds 9 Hz, there is not enough time for this pattern to complete, so every other response is different. The retina responds periodically, with a period double the period of the flashing light. When the frequency exceeds 12 Hz, the period doubles again and the retina’s response is the same only after every four flashes. When the frequency exceeds 15 Hz, the retina’s response is chaotic. The subjects say that the light appears “flickering.” This is a period doubling cascade, Feigenbaum’s classic route to chaos.((This is described in Section 9 of the accompanying report. \\ Heninger & Johnson. //Chaos and Intrinsic Unpredictability.// AI Impacts. [[http://aiimpacts.org/wp-content/uploads/2023/03/Chaos-and-Intrinsic-Unpredictability.pdf]]. \\ See also Wikipedia: [[https://en.wikipedia.org/wiki/Period-doubling_bifurcation|Period-doubling bifurcation]] or Scholarpedia: [[http://www.scholarpedia.org/article/Period_doubling|Period doubling]].)) Feigenbaum’s theory predicts that, with more precise control over the frequency of the flashing light, you could see the retina respond at 8 or 16 times the period of the flashing light, and that the period doubling bifurcations get closer together in a way characterized by Feigenbaum’s constants, before transitioning to chaos. | When shown a flash of light, the neurons in a retina (of tiger salamander larvae or humans) exhibit a particular firing pattern, which stops shortly after the flash.((Crevier & Meister. //Synchronous Period-Doubling in Flicker of Salamander and Man.// Journal of Neurophysiology **79**. (1998) p. 1869-1878. [[https://journals.physiology.org/doi/pdf/10.1152/jn.1998.79.4.1869]].)) If the flash is shown periodically, with a frequency of less than 9 Hz, the retina’s response is periodic: each flash is followed by this particular firing pattern. When the frequency exceeds 9 Hz, there is not enough time for this pattern to complete, so every other response is different. The retina responds periodically, with a period double the period of the flashing light. When the frequency exceeds 12 Hz, the period doubles again and the retina’s response is the same only after every four flashes. When the frequency exceeds 15 Hz, the retina’s response is chaotic. The subjects say that the light appears “flickering.” This is a period doubling cascade, Feigenbaum’s classic route to chaos.((This is described in Section 9 of the accompanying report. \\ Heninger & Johnson. //Chaos and Intrinsic Unpredictability.// AI Impacts. [[http://aiimpacts.org/wp-content/uploads/2023/04/Chaos-and-Intrinsic-Unpredictability.pdf]]. \\ See also Wikipedia: [[https://en.wikipedia.org/wiki/Period-doubling_bifurcation|Period-doubling bifurcation]] or Scholarpedia: [[http://www.scholarpedia.org/article/Period_doubling|Period doubling]].)) Feigenbaum’s theory predicts that, with more precise control over the frequency of the flashing light, you could see the retina respond at 8 or 16 times the period of the flashing light, and that the period doubling bifurcations get closer together in a way characterized by Feigenbaum’s constants, before transitioning to chaos. |
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| The normal firing pattern of neurons in the olfactory bulb of rabbits is chaotic.((Di Prisco & Freeman. //Odor-related bulbar EEG spatial pattern analysis during appetitive conditioning in rabbits.// Behavioral Neuroscience **99.5**. (1985) [[https://escholarship.org/content/qt7s63p7sx/qt7s63p7sx.pdf]]. \\ Freeman & Di Prisco. //Spatial patterns differences with discriminated odors manifest chaotic and limit cycles attractors in olfactory bulb of rabbits.// Brain Theory. (1986) p. 97-119.)) When exposed to a smell the rabbit has previously learned, the firing patterns cease to be chaotic and instead become periodic. The periodic motion seems to follow one of the unstable periodic orbits embedded in the original strange attractor. Each smell the rabbit has previously learned corresponds to a different periodic orbit. It seems as though the olfactory bulb is using a kind of dynamical memory storage, which allows rapid responses to learned stimuli. The smells are remembered as unstable periodic orbits within the strange attractor. | The normal firing pattern of neurons in the olfactory bulb of rabbits is chaotic.((Di Prisco & Freeman. //Odor-related bulbar EEG spatial pattern analysis during appetitive conditioning in rabbits.// Behavioral Neuroscience **99.5**. (1985) [[https://escholarship.org/content/qt7s63p7sx/qt7s63p7sx.pdf]]. \\ Freeman & Di Prisco. //Spatial patterns differences with discriminated odors manifest chaotic and limit cycles attractors in olfactory bulb of rabbits.// Brain Theory. (1986) p. 97-119.)) When exposed to a smell the rabbit has previously learned, the firing patterns cease to be chaotic and instead become periodic. The periodic motion seems to follow one of the unstable periodic orbits embedded in the original strange attractor. Each smell the rabbit has previously learned corresponds to a different periodic orbit. It seems as though the olfactory bulb is using a kind of dynamical memory storage, which allows rapid responses to learned stimuli. The smells are remembered as unstable periodic orbits within the strange attractor. |
