The Sentience Quotient concept was introduced by Robert A. Freitas Jr. in the late 1970s.1 It defines sentience as the relationship between the information processing rate (bit/s) of each individual processing unit (neuron), the weight/size of a single unit and the total number of processing units (expressed as mass). This is a nonstandard usage of the word "sentience" which in standard usage relates to an individual organism's capacity to experience sensations and emotions. (The word "sentience" is derived from the Latin "sentire" meaning "to feel" and is closely related to the word "sentiment." Intelligence or cognitive capacity is better denoted by the word "sapience" and not "sentience.") The potential and total processing capacity of a brain, based on the amount of neurons and the processing rate and mass of a single one, combined with its design (myelin coating and specialized areas and so on) and programming, lays the foundations of the brain level of the individual. Not just in humans, but in all organisms, even artificial ones such as computers (although their "brain" is not based on neurons).
DefinitionThe Sentience Quotient (SQ) of an individual is a measure of the efficiency of an individual brain, not its relative intelligence, and is defined as: where I is the information processing rate (bits/s) and M is the mass of the brain (kg). The lower (astrophysical) limit of SQ is approximately −70, while the upper (quantum) limit is about 50. Various Entities' SQAccording to this equation, humans have an SQ of +13. A human neuron has an average mass of about 10−10 kg and one neuron can process 1000-3000 bit/s, giving us an SQ rating of +13. All other animals with a nervous system (or all "neuronal sentience") from insects to mammals, cluster within several points of the human value. Plants cluster around an SQ of −2 with carnivorous plants having a SQ of +1, while computers have SQ's in the range of 6-9. The theoretical Superconducting Josephson junction electronic gates could weigh 10−12 kg and process 1011 bits/s, giving an "electronic sentience" made of these components a SQ of +23. SQ Spectrum
SQ is not limited to sentient beings so far encountered by humans, but extends to all possible sentiences, defining an expected range. The lowest SQ possible, would have just one neuron with the mass of the whole universe (1052 kg) and require a time equal to the age of the universe (1018 seconds) to process just one bit, giving a minimum SQ of -70. It has been argued that under multiverse theory, an infinitely low SQ is theoretically possible, though Freitas is not known to have commented on this possibility himself. The fundamental upper limit to intelligence is imposed by the laws of quantum mechanics: all information, to be acted upon, must be represented physically and be carried by matter-energy "markers." According to the Uncertainty Principle in quantum mechanics, the lower limit for the accuracy with which energy can be measured--the minimum measurable energy level for a marker carrying one bit–-is given by Planck's constant h divided by T, the duration of the measurement. If one energy level is used to represent one bit, then the maximum bit rate of a brain is equal to the total energy available E ( = mc02) for representing information, divided by the minimum measurable energy per bit (h/T) divided by the minimum time required for readout (T). or mc02/h = 1050 bit/s/kg. Hence the maximum possible SQ is +50. Implications for Interspecies CommunicationAccording to Freitas, an alien civilization having their consciousness running on non-biological hardware (such as quantum-mechanical circuits) could have an SQ of 23+, 10 orders of magnitude more than the Human SQ. Freitas states that such a gap in SQ "may affect our ability, and the desirability, of communicating with extraterrestrial beings...It may be that there is a minimum SQ "communication gap," an intellectual distance beyond which no two entities can meaningfully converse." 1
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Notes
ReferencesMoravec, Hans. "When will computer hardware match the human brain?" Journal of Evolution and Technology 1998, Vol. 1. Last accessed 11 April 2008. References to SQ
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