Information-Theoretic Death

A person is dead according to the information-theoretic criterion if the structures that encode memory and personality have been so disrupted that it is no longer possible in principle to recover them. If inference of the state of memory and personality are feasible in principle, and therefore restoration to an appropriate functional state is likewise feasible in principle, then the person is not dead.1

An example of information-theoretic death is a person who suffers a heart attack and is cremated.

Information-theoretic death, clinical death and legal death are three distinct concepts. A sailor lost at sea who survives on a deserted island might be declared legally dead even though he was still alive. A patient who has requested a DNR (Do Not Resuscitate) order can be pronounced clinically and legally dead on cessation of heartbeat at a point in time when he could in fact be revived. A person who was cryopreserved using "aldehyde-stabilized cryopreservation (ASC), which ... has the unique ability to combine stable long term ice-free sample storage with excellent anatomical resolution"3 would indisputably be legally and clinically dead, yet the physical structure of the brain would be preserved with such fidelity that information-theoretic death would be unlikely.16

The ability to identify synapses, neurons, and other structures critical to brain function for several hours following cessation of heart beat, blood flow and breathing suggests that information-theoretic death also does not occur for at least several hours following, for example, a massive heart attack that promptly caused legal and clinical death.18 This suggests that medical technology will eventually be able to revive individuals who have suffered multiple hours of ischemia. This idea is gaining traction in today's medical community. 20

Information-theoretic death is a concept defined within the standard Western scientific framework of thought. First, a mind can be defined by a particular instance of a brain (or an artificial brain, if and when such a thing becomes possible 22, 23, 24). Second, the brain is a physical object governed by physical law. Third, a physical object of bounded size can be specified by a sufficiently accurate description, that is, by a sufficient number of bits.2 As a consequence of these three facts, the human mind can be fully described by an appropriate digital description, much as any piece of music can be described by an MP3 file and any image can be described by a JPG file. 17, 19, 25, 26

The claim that information-theoretic death can never be reversed by any technology, no matter how advanced, must be based on a theoretical understanding of the ultimate limits of technology. That is, the claim that information-theoretic death is irreversible is based on theoretical projections of what is technologically possible within the framework of standard Western scientific theories of physical law. Should those theories or our understanding of what they allow change, then the claim would likewise need to be revisited and possibly changed. For example, if certain types of time travel should in fact prove feasible, then information-theoretic death (as presently understood) could be reversed.

What is "death"?

death \'deth\ n [ME deeth, fr. OE death; akin to ON dauthi death, deyja to die -- more at DIE] 1: a permanent cessation of all vital functions : the end of life

Webster's New Collegiate Dictionary

Determining when "a permanent cessation of all vital functions" has occurred is not always easy. Historically, premature declarations of death and subsequent burial alive have been a significant problem.

Person crawling from coffin In the seventh century, Celsus wrote "... Democritus, a man of well merited celebrity, has asserted that there are in reality, no characteristics of death sufficiently certain for physicians to rely upon."5, page 166.

"Researchers estimate that many who were buried before embalming was common were bured alive, giving credence to horror stores of claw marks found inside caskets. In 1742, John Bruier documented 52 examples of premature burial and 72 mistaken diagnoses of death and proposed that an "inspector of the dead" be appointed. In 1895, Franz Hartmann included in his book Premature Burial more than 700 cases and narrow escapes. T. M. Montgomery surveyed the burials made in Fort Randall Cemetary when it was moved in 1896 and found that nearly 2 percent of those exhumed had been victims of suspended animation. In a similar book published in 1905, William Tebb and Edward Vollum collected accounts of 219 narrow escapes, 149 premature burials, 10 cases of dissected alive, 3 almost dissected alive, and 2 who revived while being embalmed. In the early 1900s, a case of premature burial was discovered an average of once a week."21.

New Criteria

Current criteria of "death" are sufficient to ensure that spontaneous recovery in the mortuary or later is a rare, but not unheard of, occurrence.13, 14 When examined closely, current criteria are simply a codified summary of symptoms that have proven resistant to treatment by available techniques. Historically, they derive from the fear that the patient will spontaneously recover in the morgue or crypt. There is no underlying theoretical structure to support them, only a continued accumulation of ad hoc rules supported by empirical evidence. "We are left with rather unsatisfying results. Most of the data do not quite show that persons meeting a given set of criteria have, in fact, irreversibly lost brain function. They show that patients lose heart function soon, or that they do not 'recover.'" 4 In short, current criteria are adequate to determine if current medical technology is likely to fail to revive a patient, but are silent on the capabilities of future medical technology.

An example from computer technology is in order. If a computer is fully functional then its memory and "personality" are completely intact. If it fell out the seventh floor window to the concrete below, it would rapidly cease to function. However, its memory and "personality" would still be present in the pattern of magnetizations on the disk. With sufficient effort, we could completely repair the computer with its memory and "personality" intact.

In a similar fashion, as long as the structures that encode the memory and personality of a person12 have not been irretrievably obliterated then restoration to a fully functional state with memory and personality intact is likewise feasible in principle.

On the flip side of the coin, if the structures encoding memory and personality have suffered sufficient damage to obliterate them beyond recognition, then death by the information-theoretic criterion has occurred. An effective method of ensuring such destruction is to burn the structure and stir the ashes. This is commonly employed to ensure the destruction of classified documents. Under the name of "cremation" it is also employed on human beings and is sufficient to ensure that death by the information-theoretic criterion takes place.

The Social Purpose of "Death"

By definition, "death" is the point where the moral obligation to look after a patient ends, where what was once a person becomes a "dead body", a "corpse", or "remains" that can be disposed of in accordance with an entirely different set of social, legal and moral conventions.

The problem is that "death" is usually based only in part on the physical condition of the patient. Whether or not someone is "dead" is also determined by the patient's wishes, the attending physician's views, whether another patient with a better prognosis requires resources, whether the patient is donating an organ, the available equipment, and a variety of other factors. In the case of the sailor lost at sea, the dependence on the physical condition of the patient is entirely lost.

"Death" is not a change in the patient, but in their standing within the group.

As a practical matter, modern medicine is exacerbating the fundamental ambiguity in the definition of "death", a fact that is sometimes expressed by saying that the line between "life" and "death" is become increasingly blurred.7, 8, 9, 27 If your heart stops, are you dead? Or merely in need of more advanced medical treatment? The answer depends on where you are and who's asking.

When changing technology collides with deeply entrenched traditions and prejudices the results can be intensely emotional and deeply unsettling. We already see this happening today with our existing medical technology, and we can anticipate greater change in the future.

The most disorienting collision between tradition and advancing medical technology occurs with cryonics, where it is literally the case that the medical care of the patient today depends on the medical technology that we anticipate will be feasible a century or more from now.10 If a cryopreserved patient can be resuscitated in the year 2100, then it makes sense to cryopreserve that patient today if contemporary medicine can no longer sustain them.

Patients who would traditionally be declared "dead" are not considered "dead" by the new criteria. Continuing their care creates confusion, cognitive dissonance, and sometimes hostility from those still using the traditional criteria. Ethically, however, it seems inappropriate to prevent a terminally ill patient from paying their own money to pursue their favored treatment option, 15  especially when there is a plausible chance of success.11

Further references are available in an earlier version of the Wikipedia page on this topic. 28

1. The original definition, as published, was "A person is dead according to the information-theoretic criterion if their memories, personality, hopes, dreams, etc. have been destroyed in the information-theoretic sense. If the structures in the brain that encode memory and personality have been so disrupted that it is no longer possible in principle to recover them, then the person is dead. If they are sufficiently intact that inference of the state of memory and personality are feasible in principle, and therefore restoration to an appropriate functional state is likewise feasible in principle, then the person is not dead."

Merkle, R (1992). The technical feasibility of cryonics, Medical Hypotheses (Elsevier) 39 (1): 6–16. doi:10.1016/0306-9877(92)90133-W.

2. All physical objects can be described in perfect detail by a sufficient number of bits, as a consequence of the Bekenstein bound."In physics, the Bekenstein bound is an upper limit on the entropy S, or information I, that can be contained within a given finite region of space which has a finite amount of energy—or conversely, the maximum amount of information required to perfectly describe a given physical system down to the quantum level. It implies that the information of a physical system, or the information necessary to perfectly describe that system, must be finite if the region of space and the energy is finite." Wikipedia,

Vastly fewer bits than the limit given by the Bekenstein bound are required to describe a brain in sufficient detail to capture all aspects of a particular person's memory and personality. 17

3. "We describe here a new cryobiological and neurobiological technique, aldehyde-stabilized cryopreservation (ASC), which ... has the unique ability to combine stable long term ice-free sample storage with excellent anatomical resolution. ... we perfuse-fixed rabbit and pig brains with a glutaraldehyde-based fixative, then slowly perfused increasing concentrations of ethylene glycol over several hours in a manner similar to techniques used for whole organ cryopreservation. Once 65% w/v ethylene glycol was reached, we vitrified brains at −135 °C for indefinite long-term storage."

Aldehyde-stabilized cryopreservation, by Robert L. McIntyre and Gregory M. Fahy, Cryobiology Volume 71, Issue 3, December 2015, pages 448–458.

See also: 21st Century Medicine’s Aldehyde-Stabilized Cryopreservation,"

4. Death, Dying, and the Biological Revolution, revised edition, by Robert M. Veatch, Yale University Press 1989.

5. Cerebral Death by A. Earl Walker, Second Edition, Urban and Schwarzenberg 1981.

6. Wowk, B (2014). "The future of death". Journal of Critical Care (Elsevier) 29 (6): 1111–1113. doi:10.1016/j.jcrc.2014.08.006.

7. "The practice of cryopreserving people immediately after they have been pronounced medico-legally dead is called cryonics. A physician will pronounce a patient using cardio-respiratory criteria, whereupon the patient is legally dead, and the rules pertaining to procedures that can be performed change radically, since the individual is no longer a living patient but declared a corpse. In the initial cryopreservation protocol, the subject is intubated and mechanically ventilated, and a highly efficient mechanical cardiopulmonary resuscitation device reestablishes circulation, thus calling into question the prior declaration of death using the cardio-respiratory standard. In some cases, the subject begins to show ‘signs of life’, including pupillary reaction and spontaneous motion. This raises crucial questions, such as are such persons alive again, or were these subjects ever really dead?"

Whetstine, L; Streat, S; Darwin, M; Crippen, D (2005). "Pro/con ethics debate: When is dead really dead?". Critical Care (BioMed Central) 9(6): 538–542. doi:10.1186/cc3894.

8. Crippen, DW; Whetstine, L (2007). "Ethics review: Dark angels – the problem of death in intensive care". Critical Care (BioMed Central) 11 (1): 202. doi:10.1186/cc5138.

9. The Observer, April 6th, 2013: "Sam Parnia – the man who could bring you back from the dead" – '"The longest I know of is a Japanese girl I mention in the book," Parnia says. "She had been dead for more than three hours. ... Afterwards, she returned to life perfectly fine and has, I have been told, recently had a baby."' "One of the stranger things you realise in reading Parnia's book is the idea that we might be in thrall to historical perceptions of life and death and that these ultimate constants have lately become vaguer than most of us would allow."

10. Wowk, B. (2004). Medical Time Travel, from The Scientific Conquest of Death, 2004, ISBN: 9875611352.

11. PBS, November 18, 2015, "The Brain with David Eagleman: Episode 6 | Cryonic Preservation of the Brain and Body"

12. Synapses and Memory Storage by Mayford M, Siegelbaum SA, and Kandel ER. Cold Spring Harbor Perspectives in Biology, April 10, 2012.

13. Premature burial, Wikipedia.

14. 15 Dead People Who Came Back To Life, Youtube, Jun 24, 2014 Also see

15. "Each patient is a free agent entitled to full explanation and full decision-making authority with regard to his medical care. John Stuart Mill expressed it as: "Over himself, his own body and mind, the individual is sovereign." The legal counterpart of patient autonomy is self-determination. Both principles deny legitimacy to paternalism by stating unequivocally that, in the last analysis, the patient determines what is right for him."

"If the [terminally ill] patient is a mentally competent adult, he has the legal right to accept or refuse any form of treatment, and his wishes must be recognized and honored by his physician."

American College of Physicians Ethics Manual. Part II: Research, Other Ethical Issues. Recommended Reading; The Ad Hoc Committee on Medical Ethics, American College of Physicians; Annals of Internal Medicine, July 1984; Vol. 101 No. 2, pages 263-267.

16. ”While the preserved brain was dead tissue, all of its synaptic connections — or the junctions of nerve cells — were maintained, Robert McIntyre, a scientist at company 21st Century Medicine who led the research, told The Huffington Post. “This research is a first because it works on whole brains and preserves all of the synaptic details,” he said. “Previous techniques, such as resin embedding, are only able to preserve detailed synaptic information in small brain slices.” ” Cryogenically Frozen Rabbit Brain Hailed As Scientific First, February 11, 2016, Huffington Post,

17. How many bytes in human memory?, by Ralph C. Merkle, Foresight Update No. 4, October 1988.

18. "Postmortem" Changes in the Human Brain, from Molecular Repair of the Brain, by Ralph C. Merkle.

19. Nanoconnectomic upper bound on the variability of synaptic plasticity by Thomas M Bartol Jr., Cailey Bromer, Justin Kinney, Michael A Chirillo, Jennifer N Bourne, Kristen M Harris, and Terrence J Sejnowski; November 30, 2015, eLife 2015;4:e10778. DOI:

20. Newsweek, May 7, 2007: Docs Change the Way They Think About Death, ""After one hour," he says, "we couldn't see evidence the cells had died. We thought we'd done something wrong." In fact, cells cut off from their blood supply died only hours later."

21. Christine Quigley, The Corpse: A History (1996) McFarland & Company. See also Taphophobia,

22. "An `artificial brain' is not possible at present, but a walking, talking, thinking individual who had one would certainly be considered living." Death, Dying, and the Biological Revolution, revised edition, by Robert M. Veatch, Yale University Press 1989, page 23.

23. "If machines do come to simulate all of our internal cognitive activities, to the last computational detail, to deny them the status of genuine persons would be nothing but a new form of racism." Matter and Consciousness: A Contemporary Introduction to the Philosophy of Mind, by Paul Churchland, second edition, 1988, the MIT press, page 120.

24. "Body-identity assumes that a person is defined by the stuff of which a human body is made. Only by maintaining continuity of body stuff can we preserve an individual person. Pattern-identity, conversely, defines the essence of a person, say myself, as the pattern and the process going on in my head and body, not the machinery supporting that process. If the process is preserved, I am preserved. The rest is mere jelly." Mind Children by Hans Moravec, Harvard University Press, 1988. page 117

25. Your Brain’s Technical Specs: How many megabytes of data can the human mind hold? By Forrest Wickman, Slate,

26. If your brain were a computer, how much storage space would it have? by Robbie Gonzalez, io9, May 24 2013.

27. Newsweek, July 22, 2007: Back to Life: The Science of Reviving the Dead. Ralph Merkle "has used this idea to popularize a fourth definition of death: "information-theoretic" death, the point at which the brain has succumbed to the pull of entropy and the mind can no longer be reconstituted. Only then, he says, are you really and truly dead."

28. Wikipedia, June 10 2016: Information-theoretic death,