Immortality

==Physical immortality==
Physical immortality is a state of life that allows a person to avoid death and maintain conscious thought. It can mean the unending existence of a person from a physical source other than organic life, such as a computer.

Pursuit of physical immortality before the advent of modern science included [[alchemy|alchemists]], who sought to create the [[Philosopher's stone|Philosopher's Stone]],<ref name="Paracelsus">Theophrastus Paracelsus. ''The Book of the Revelation of Hermes''. 16th century</ref> and various cultures' legends such as the [[Fountain of Youth]] or the [[Peaches of Immortality]] inspiring attempts at discovering an [[elixir of life]].{{sfn|Zorea|2017|pp=35–39}}{{sfn|Endsjø|2023|pp=88–100}}

Modern scientific trends, such as [[cryonics]], [[digital immortality]], breakthroughs in [[rejuvenation (aging)|rejuvenation]], or predictions of an impending [[technological singularity]], to achieve genuine human physical immortality, must still overcome all causes of death to succeed.{{sfn|Alexander|2003|pp=45-57}}{{sfn|Bolonkin|2010|pp=72-83}}

===Causes of death===
{{Main|Death}}
There are three main causes of death: [[aging|natural aging]], [[disease]], and [[physical trauma|injury]].<ref>{{cite journal |last=Hayflick |first=L. |year=2007 |title=Biological aging is no longer an unsolved problem |journal=Annals of the New York Academy of Sciences |volume=1100 |issue=1 |pages=1–13 |doi=10.1196/annals.1395.001 |pmid=17460161 |bibcode=2007NYASA1100....1H |s2cid=14685889}}{{dead link|date=December 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Such issues can be resolved with the solutions provided in research to any end providing such alternate theories at present that require unification.

====Aging====
[[Aubrey de Grey]], a leading researcher in the field,<ref name="Garreau">{{cite news |first=Joel |last=Garreau |author-link=Joel Garreau |date=31 October 2007 |title=The Invincible Man |newspaper=[[The Washington Post]] |page=C‑01 |url=https://www.washingtonpost.com/wp-dyn/content/article/2007/10/30/AR2007103002222_pf.html}}</ref> defines [[aging]] as "a collection of cumulative changes to the [[molecular]] and [[cell (biology)|cellular]] structure of an adult [[organism]], which result in essential [[metabolic]] processes, but which also, once they progress far enough, increasingly disrupt metabolism, resulting in [[pathology]] and death." The current causes of aging in humans are cell loss (without replacement), [[DNA damage theory of aging|DNA damage]], [[oncology|oncogenic]] [[cell nucleus|nuclear]] [[mutation]]s and [[epimutation]]s, cell [[senescence]], [[mitochondria]]l mutations, [[lysosomal]] aggregates, extracellular aggregates, random extracellular cross-linking, [[immune system]] decline, and [[endocrine]] changes. Eliminating aging would require finding a solution to each of these causes, a program de Grey calls [[Strategies for engineered negligible senescence|engineered negligible senescence]]. There is also a huge body of knowledge indicating that change is characterized by the loss of molecular fidelity.<ref>{{cite book |last1=Bernstein |first1=C. |last2=Bernstein |first2=H. |year=1991 |title=Aging, Sex, and DNA Repair |publisher=Academic Press |place=San Diego, CA |isbn=978-0120928606}} {{ISBN|0120928604}}</ref>

====Disease====
Disease is theoretically surmountable by technology. In short, it is an abnormal condition affecting the body of an organism, something the body should not typically have to deal with its natural make up.<ref>{{cite web |title=Classification of diseases functioning and disability |date=23 July 2021 |url=https://www.cdc.gov/nchs/icd.htm}}</ref> Human understanding of [[genetics]] is leading to cures and treatments for a myriad of previously incurable diseases. The mechanisms by which other diseases do damage are becoming better understood. Sophisticated methods of detecting diseases early are being developed. [[Preventative medicine]] is becoming better understood. Neurodegenerative diseases like [[Parkinson's disease|Parkinson's]] and [[Alzheimer's disease|Alzheimer's]] may soon be curable with the use of [[stem cells]]. Breakthroughs in [[cell biology]] and [[telomere]] research are leading to treatments for cancer. [[Vaccine]]s are being researched for AIDS and [[tuberculosis]]. Genes associated with [[type 1 diabetes]] and certain types of cancer have been discovered, allowing for new therapies to be developed. Artificial devices attached directly to the [[nervous system]] may restore sight to the blind. Drugs are being developed to treat a myriad of other diseases and ailments.

====Trauma====
[[Physical trauma]] would remain as a threat to perpetual physical life, as an otherwise immortal person would still be subject to unforeseen accidents or catastrophes. The speed and quality of [[paramedic]] [[disaster relief operation|response]] remains a determining factor in surviving severe trauma.<ref name=walker>{{cite book |last=Walker |first=Peter |date=1991 |title=International Search and Rescue Teams |series=League Discussion Paper |publisher=[[IFRC|League of the Red Cross and Red Crescent Societies]] |place=Geneva, CH}}</ref> A body that could automatically repair itself from severe trauma, such as speculated uses for [[nanotechnology]], would mitigate this factor. The brain cannot be risked to trauma if a continuous physical life is to be maintained. This aversion to trauma risk to the brain would naturally result in significant behavioral changes that would render physical immortality undesirable for some people.

====Environmental change====
{{Unreferenced section|date=November 2022}}
Organisms otherwise unaffected by these causes of death would still face the problem of obtaining sustenance (whether from currently available agricultural processes or from hypothetical future technological processes) in the face of changing availability of suitable resources as environmental conditions change. After avoiding aging, disease, and trauma, death through resource limitation is still possible, such as [[Hypoxia (medical)|hypoxia]] or [[starvation]].

If there is no limitation on the degree of gradual mitigation of risk then it is possible that the [[cumulative probability]] of death over an infinite horizon is less than [[certainty]], even when the risk of fatal trauma [[Hazard rate|in any finite period]] is greater than zero. Mathematically, this is an aspect of achieving [[Indefinite lifespan#Actuarial escape velocity|'actuarial escape velocity']].

===Biological immortality===
[[File:Telomere caps.gif|thumb|right|Human [[chromosome]]s (grey) capped by telomeres (white)]]
{{Main|Biological immortality}}

Biological immortality is an absence of aging. Specifically it is the absence of a sustained increase in [[rate of mortality]] as a function of chronological age. A cell or organism that does not experience aging, or ceases to age at some point, is biologically immortal.<ref>{{cite web|url=http://www.immortality.foundation/aging|title=What is Aging?|access-date=6 November 2020}}</ref>

[[Biologist]]s have chosen the word "immortal" to designate cells that are not limited by the [[Hayflick limit]], where cells no longer divide because of [[DNA repair|DNA damage]] or shortened [[telomere]]s. The first and still most widely used immortal cell line is [[HeLa]], developed from cells taken from the malignant cervical tumor of [[Henrietta Lacks]] without her consent in 1951. Prior to the 1961 work of [[Leonard Hayflick]], there was the erroneous belief fostered by [[Alexis Carrel]] that all normal [[Somatic (biology)|somatic]] cells are immortal. By preventing cells from reaching senescence one can achieve biological immortality; telomeres, a "cap" at the end of DNA, are thought to be the cause of cell aging. Every time a cell divides the telomere becomes a bit shorter; when it is finally worn down, the cell is unable to split and dies. [[Telomerase]] is an enzyme which rebuilds the telomeres in stem cells and cancer cells, allowing them to replicate an infinite number of times.<ref name="LinKahWai">{{cite journal |author=Lin Kah Wai |author-link=Lin Kah Wai |title=Telomeres, Telomerase, and Tumorigenesis – A Review |journal=MedGenMed |date=18 April 2004 |volume=6 |issue=3 |page=19 |pmid=15520642 |pmc=1435592}}</ref> No definitive work has yet demonstrated that telomerase can be used in human somatic cells to prevent healthy tissues from aging. On the other hand, scientists hope to be able to grow organs with the help of stem cells, allowing organ transplants without the risk of rejection, another step in extending human life expectancy. These technologies are the subject of ongoing research, and are not yet realized.<ref>{{cite news|url=https://www.nytimes.com/2017/01/26/science/chimera-stemcells-organs.html|title=New Prospects for Growing Human Replacement Organs in Animals|website=[[The New York Times]]|date=26 January 2017 |access-date=3 March 2018|last1=Wade |first1=Nicholas }}</ref>

====Biologically immortal species====
{{see also|List of longest-living organisms}}

Life defined as biologically immortal is still susceptible to causes of death besides aging, including disease and trauma, as defined above. Notable immortal species include:
* ''Bacteria'' – Bacteria reproduce through [[Fission (biology)|binary fission]]. A parent bacterium splits itself into two identical daughter cells which eventually then split themselves in half. This process repeats, thus making the bacterium essentially immortal. A 2005 [[PLoS Biology]] paper<ref>{{cite web|url= http://hal.archives-ouvertes.fr/docs/00/08/01/54/PDF/stewart_Plos.pdf|title= Aging and Death in an Organism That Reproduces by Morphologically Symmetric Division}}</ref> suggests that after each division the daughter cells can be identified as the older and the younger, and the older is slightly smaller, weaker, and more likely to die than the younger.<ref>{{cite web |url=https://www.newscientist.com/channel/health/mg18524855.800-bacteria-death-reduces-human-hopes-of-immortality.html |title=Bacteria Death Reduces Human Hopes of Immortality |date=5 February 2005 |website=New Scientist magazine, issue 2485| page= 19 |access-date=2 April 2007}}</ref>
* ''[[Turritopsis dohrnii]]'', a jellyfish (phylum [[Cnidaria]], class [[Hydrozoa]], order [[Anthoathecata]]), after becoming a sexually mature adult, can transform itself back into a [[polyp (zoology)|polyp]] using the cell conversion process of [[transdifferentiation]].<ref name="CheatingDeath">{{cite web|url=http://10e.devbio.com/article.php?ch=2&id=6|title=Cheating Death: The Immortal Life Cycle of Turritopsis|last=Gilbert|first=Scott F.|date=2006|access-date=14 June 2009|url-status=dead|archive-url=https://web.archive.org/web/20151121052612/http://10e.devbio.com/article.php?ch=2&id=6|archive-date=21 November 2015}}</ref> ''Turritopsis dohrnii'' repeats this cycle, meaning that it may have an [[indefinite lifespan]].<ref name="CheatingDeath" /> Its immortal adaptation has allowed it to spread from its original habitat in the Caribbean to "all over the world".<ref name="Telegraph-immortal-jellyfish">{{cite news |url=https://www.telegraph.co.uk/earth/wildlife/4357829/Immortal-jellyfish-swarming-across-the-world.html |archive-url=https://web.archive.org/web/20090130115250/http://www.telegraph.co.uk/earth/wildlife/4357829/Immortal-jellyfish-swarming-across-the-world.html |url-status=dead |archive-date=30 January 2009 |title={{-'}}Immortal' jellyfish swarming across the world |date=30 January 2009 |publisher=[[Telegraph Media Group]] |access-date= 14 June 2009 |location=London}}</ref><ref>{{cite web|url=http://news.nationalgeographic.com/news/2009/01/090130-immortal-jellyfish-swarm.html|archive-url=https://web.archive.org/web/20090202063305/http://news.nationalgeographic.com/news/2009/01/090130-immortal-jellyfish-swarm.html|url-status=dead|archive-date=2 February 2009|title="Immortal" Jellyfish Swarm World's Oceans|website=news.nationalgeographic.com|date=29 January 2009|access-date=19 August 2017}}</ref>
* ''[[Hydra (genus)|Hydra]]'' is a [[genus]] belonging to the phylum [[Cnidaria]], the class [[Hydrozoa]] and the order [[Anthomedusae]]. They are simple fresh-water [[predatory]] animals possessing [[symmetry (biology)#Radial symmetry|radial symmetry]].<ref>Gilberson, Lance, ''Zoology Lab Manual'', 4th edition. Primis Custom Publishing. 1999.</ref><ref>{{Cite news|url=https://www.livescience.com/53178-hydra-may-live-forever.html|title=Hail the Hydra, an Animal That May Be Immortal|work=Live Science|access-date=19 August 2017}}</ref>

====Evolution of aging====
{{Main|Evolution of aging}}<!--that's how they spell aging in England ... and in that article-->
As the existence of biologically immortal species demonstrates, there is no [[second law of thermodynamics|thermodynamic]] necessity for senescence: a defining feature of life is that it takes in [[Gibbs free energy|free energy]] from the environment and unloads its [[entropy]] as waste. Living systems can even build themselves up from seed, and routinely repair themselves. Aging is therefore presumed to be a byproduct of [[evolution]], but why mortality should be selected for remains a subject of research and debate. Programmed cell death and the telomere "end replication problem" are found even in the earliest and simplest of organisms.<ref>Clark, W.R. 1999. ''A Means to an End: The biological basis of aging and death.'' New York: Oxford University Press. {{cite web |url=http://wrclarkbooks.com/means_to_an_end.html |title=A Means to an End - Why do we age? Is aging inevitable? Questions and Answers are available here by downloading a sample chapter of WR Clark's book. The WRClark Site also features a chat room for you to ask your questions about aging |access-date=25 May 2008 |url-status=dead |archive-url=https://web.archive.org/web/20080511212036/http://www.wrclarkbooks.com/means_to_an_end.html |archive-date=11 May 2008 }} About telomeres and programmed cell death.</ref> This may be a tradeoff between selecting for cancer and selecting for aging.<ref>Harrison, ''Principles of Internal Medicine'', Ch. 69, "Cancer cell biology and angiogenesis", Robert G. Fenton and Dan L. Longo, p. 454.</ref>

Modern theories on the evolution of aging include the following:
* Mutation accumulation is a theory formulated by [[Peter Medawar]] in 1952 to explain how evolution would select for aging. Essentially, aging is never selected against, as organisms have offspring before the mortal mutations surface in an individual.
* [[Pleiotropy|Antagonistic pleiotropy]] is a theory proposed as an alternative by [[George C. Williams (biologist)|George C. Williams]], a critic of Medawar, in 1957. In antagonistic pleiotropy, genes carry effects that are both beneficial and detrimental. In essence this refers to genes that offer benefits early in life, but exact a cost later on, i.e. decline and death.<ref>Williams, G.C. 1957. Pleiotropy, natural selection and the evolution of senescence. ''Evolution'', '''11''':398–411. {{cite web|url=http://www.telomere.org/Downloads/Williams_searchable.pdf |title=Archived copy |access-date=23 July 2006 |url-status=dead |archive-url=https://web.archive.org/web/20060713071204/http://www.telomere.org/Downloads/Williams_searchable.pdf |archive-date=13 July 2006 }} Paper in which Williams describes his theory of antagonistic pleiotropy.</ref>
* The disposable soma theory was proposed in 1977 by [[Tom Kirkwood|Thomas Kirkwood]], which states that an individual body must allocate energy for metabolism, reproduction, and maintenance, and must compromise when there is food scarcity. Compromise in allocating energy to the repair function is what causes the body gradually to deteriorate with age, according to Kirkwood.<ref>Kirkwood, T.B.L. 1977. Evolution of aging. ''Nature'', '''270''': 301–304. [http://www.nature.com/nature/journal/v270/n5635/abs/270301a0.html] Origin of the disposable soma theory.</ref>

====Immortality of the germline====

Individual organisms ordinarily age and die, while the germlines which connect successive generations are potentially immortal. The basis for this difference is a fundamental problem in biology.   The Russian biologist and historian [[Zhores A. Medvedev]]<ref name="Medvedev1981">{{cite journal |last=Medvedev |first=Zhores A. |title=On the immortality of the germ line: Genetic and biochemical mechanisms. A review |journal=Mechanisms of Ageing and Development |volume=17 |issue=4 |year=1981 |pages=331–359 |issn=0047-6374 |doi=10.1016/0047-6374(81)90052-X|pmid=6173551 |s2cid=35719466 }}</ref> considered that the accuracy of [[genome]] replicative and other synthetic systems alone cannot explain the immortality of [[germline]]s. Rather Medvedev thought that known features of the biochemistry and genetics of [[sexual reproduction]] indicate the presence of unique information maintenance and restoration processes at the different stages of [[gametogenesis]]. In particular, Medvedev considered that the most important opportunities for information maintenance of [[germ cell]]s are created by [[genetic recombination|recombination during meiosis]] and [[DNA repair]]; he saw these as processes within the germ cells that were capable of restoring the integrity of [[DNA]] and [[chromosome]]s from the types of damage that cause irreversible aging in [[somatic cell]]s.

===Prospects for human biological immortality===

====Life-extending substances====
Some{{who|date=July 2021}} scientists believe that boosting the amount or proportion of [[telomerase]] in the body, a naturally forming enzyme that helps maintain the protective caps at the ends of [[chromosome]]s, could prevent cells from dying and so may ultimately lead to extended, healthier lifespans. A team of researchers at the Spanish National Cancer Centre ([[Madrid]]) tested the hypothesis on mice. It was found that those mice which were "[[genetic engineering|genetically engineered]] to produce 10 times the normal levels of telomerase lived 50% longer than normal mice".<ref>{{cite news |url=https://www.telegraph.co.uk/health/healthnews/3489881/Scientists-take-a-step-closer-to-an-elixir-of-youth.html |archive-url=https://web.archive.org/web/20081201081233/http://www.telegraph.co.uk/health/healthnews/3489881/Scientists-take-a-step-closer-to-an-elixir-of-youth.html |url-status=dead |archive-date=1 December 2008 |work=The Daily Telegraph |location=London |title=Scientists take a step closer to an elixir of youth |first=Richard |last=Alleyne |date=20 November 2008 |access-date=5 May 2010}}</ref>

In normal circumstances, without the presence of telomerase, if a cell divides repeatedly, at some point all the progeny will reach their [[Hayflick limit]]. With the presence of telomerase, each dividing cell can replace the lost bit of [[DNA]], and any single cell can then divide unbounded. While this unbounded growth property has excited many researchers, caution is warranted in exploiting this property, as exactly this same unbounded growth is a crucial step in enabling cancerous growth. If an organism can replicate its body cells faster, then it would theoretically stop aging.

[[Embryonic stem cells]] express telomerase, which allows them to divide repeatedly and form the individual. In adults, telomerase is highly expressed in cells that need to divide regularly (e.g., in the immune system), whereas most [[Somatic (biology)|somatic]] cells express it only at very low levels in a cell-cycle dependent manner.

====Technological immortality, biological machines, and  "swallowing the doctor"====
{{Main|Molecular machine}}

Technological immortality is the prospect for much longer life spans made possible by scientific advances in a variety of fields: nanotechnology, emergency room procedures, genetics, [[biological engineering]], [[regenerative medicine]], [[microbiology]], and others. Contemporary life spans in the advanced industrial societies are already markedly longer than those of the past because of better nutrition, availability of health care, standard of living and bio-medical scientific advances.{{citation needed|date=October 2021}} Technological immortality predicts further progress for the same reasons over the near term. An important aspect of current scientific thinking about immortality is that some combination of [[human cloning]], cryonics or nanotechnology will play an essential role in extreme life extension. [[Robert Freitas]], a nanorobotics theorist, suggests tiny medical [[nanorobot]]s could be created to go through human bloodstreams, find dangerous things like cancer cells and bacteria, and destroy them.<ref>Robert A. Freitas Jr., ''Microbivores: Artificial Mechanical Phagocytes using Digest and Discharge Protocol'', self-published, 2001 [http://www.rfreitas.com/Nano/Microbivores.htm]</ref> Freitas anticipates that gene-therapies and nanotechnology will eventually make the human body effectively self-sustainable and capable of living indefinitely in empty space, short of severe brain trauma. This supports the theory that we will be able to continually create biological or synthetic replacement parts to replace damaged or dying ones. Future advances in [[nanomedicine]] could give rise to [[life extension#Nanotechnology|life extension]] through the repair of many processes thought to be responsible for aging. [[K. Eric Drexler]], one of the founders of [[nanotechnology]], postulated cell repair devices, including ones operating within cells and using as yet hypothetical [[biological machine]]s, in his 1986 book [[Engines of Creation]]. [[Raymond Kurzweil]], a [[futurist]] and [[transhumanist]], stated in his book ''[[The Singularity Is Near]]'' that he believes that advanced medical [[nanorobotics]] could completely remedy the effects of aging by 2030.<ref>{{Cite book |first=Ray |last=Kurzweil |author-link=Raymond Kurzweil |year=2005 |title=The Singularity Is Near |publisher=[[Viking Press]] |location=New York City |isbn=978-0-670-03384-3 |oclc=57201348|title-link=The Singularity Is Near }}{{Page needed|date=September 2010}}</ref> According to [[Richard Feynman]], it was his former graduate student and collaborator [[Albert Hibbs]] who originally suggested to him (circa 1959) the idea of a ''medical'' use for Feynman's theoretical micromachines (see [[biological machine]]). Hibbs suggested that certain repair machines might one day be reduced in size to the point that it would, in theory, be possible to (as Feynman put it) "swallow the doctor". The idea was incorporated into Feynman's 1959 essay ''[[There's Plenty of Room at the Bottom]].''<ref>{{cite web
 |url=http://www.its.caltech.edu/~feynman/plenty.html
 |title=There's Plenty of Room at the Bottom
 |author=Richard P. Feynman
 |date=December 1959
 |access-date=1 March 2010
|url-status=dead
 |archive-url=https://web.archive.org/web/20100211190050/http://www.its.caltech.edu/~feynman/plenty.html
 |archive-date=11 February 2010
}}</ref>

====Cryonics====
{{Unreferenced section|date=November 2022}}
{{Main|Cryonics}}

[[Cryonics]], the practice of preserving organisms (either intact specimens or only their brains) for possible future revival by storing them at cryogenic temperatures where metabolism and decay are almost completely stopped, can be used to 'pause' for those who believe that life extension technologies will not develop sufficiently within their lifetime. Ideally, cryonics would allow clinically dead people to be brought back in the future after cures to the patients' diseases have been discovered and [[rejuvenation (aging)|aging is reversible]]. Modern cryonics procedures use a process called [[Cryopreservation#Vitrification|vitrification]] which creates a glass-like state rather than [[freezing]] as the body is brought to low temperatures. This process reduces the risk of ice crystals damaging the cell-structure, which would be especially detrimental to cell structures in the brain, as their minute adjustment evokes the individual's mind.

====Mind-to-computer uploading====
{{Main|Mind uploading}}

One idea that has been advanced involves [[Mind uploading|uploading]] an individual's habits and memories via [[direct mind-computer interface]]. The individual's memory may be loaded to a computer or to a new organic body. [[Extropian]] [[futures studies|futurists]] like Moravec and [[Ray Kurzweil|Kurzweil]] have proposed that, thanks to [[exponential growth|exponentially growing]] computing power, it will someday be possible to [[mind uploading|upload human consciousness]] onto a computer system, and exist indefinitely in a virtual environment.

This could be accomplished via advanced cybernetics, where computer hardware would initially be installed in the brain to help sort memory or accelerate thought processes. Components would be added gradually until the person's entire brain functions were handled by artificial devices, avoiding sharp transitions that would lead to issues of [[identity (social science)|identity]], thus running the risk of the person to be declared dead and thus not be a legitimate owner of his or her property. After this point, the human body could be treated as an optional accessory and the program implementing the person could be transferred to any sufficiently powerful computer.

Another possible mechanism for mind upload is to perform a detailed scan of an individual's original, organic brain and simulate the entire structure in a computer. What level of detail such scans and simulations would need to achieve to emulate awareness, and whether the scanning process would destroy the brain, is still to be determined.{{efn|
The basic idea is to take a particular brain, scan its structure in detail, and construct a software model of it that is so faithful to the original that, when run on appropriate hardware, it will behave in essentially the same way as the original brain.
::: — Sandberg & Boström (2008)<ref name=Sandberg-Boström-2008-Roadmap>
{{cite book
 |last1=Sandberg |first1= Anders
 |last2=Boström  |first2=Nick 
 |year=2008
 |title=Whole Brain Emulation: A roadmap
 |series=Technical Report
 |volume=#2008-3
 |publisher=Oxford University
 |department=Future of Humanity Institute
 |url=http://www.fhi.ox.ac.uk/Reports/2008-3.pdf
 |access-date=5 April 2009
}}
</ref>
}}

It is suggested that achieving immortality through this mechanism would require specific consideration to be given to the role of [[consciousness]] in the functions of the [[mind]]. An uploaded mind would only be a copy of the original mind, and not the conscious mind of the living entity associated in such a transfer. Without a simultaneous upload of consciousness, the original living entity remains mortal, thus not achieving true immortality.<ref>
{{cite web
 |last=Ruparel |first=Bhavik
 |date=30 July 2018
 |title=On achieving immortality
 |website=Iva.to
 |url=https://medium.com/iva-to/on-achieving-immortality-3ed1d567f7a2
 |access-date=10 September 2018
}}
</ref>
Research on [[neural correlates of consciousness]] is yet inconclusive on this issue. Whatever the route to mind upload, persons in this state could then be considered essentially immortal, short of loss or traumatic destruction of the machines that maintained them.{{clarify|date=October 2015}}{{citation needed|date=September 2021}}

====Cybernetics====
{{Unreferenced section|date=November 2022}}
{{Main|Cyborg}}

Transforming a human into a [[cyborg]] can include [[brain implants]] or extracting a human processing unit and placing it in a robotic life-support system.<ref>{{cite web |last1=Melbourne |first1=Dr Alan Lai, University of |title=Part human, part robot: The future of medical implantables |url=https://pursuit.unimelb.edu.au/articles/part-human-part-robot-the-future-of-medical-implantables |website=Pursuit |access-date=2 January 2024 |language=en |date=12 September 2017}}</ref> Even replacing biological organs with robotic ones could increase life span (e.g. pace makers) and depending on the definition, many technological upgrades to the body, like genetic modifications or the addition of nanobots would qualify an individual as a cyborg. Some people believe that such modifications would make one impervious to aging and disease and theoretically immortal unless killed or destroyed.{{citation needed|date=January 2021}}

====Digital immortality====
{{Main|Digital immortality}}