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Illustration by James O'Brien

The Science of Immortality

Investigations into the biology, philosophy, and theology of immortality research

Illustration credit: James O’Brien

Cover image of a research paper on the science and theory of immortality research

Cover image of a research paper on the science and theory of immortality research.

In the Greek myth of Tithonus, the goddess of the dawn falls in love with a Trojan prince and asks Zeus to render him immortal so that the lovers could spend eternity together. However, she neglects to request that Tithonus be granted eternal youth in addition to eternal life. As a result, the immortal Tithonus suffers from the painful decay and degradation of his body over time, eventually shriveling down into a cricket.

The prospect of living forever has fascinated human beings for millennia, but it is not a concept without its challenges: the physical body breaks down, the soul is mysterious, and the prospect of infinite time raise philosophical puzzles about what it would be like to exist eternally — and whether it would even be pleasant to do so.

Questions of the plausibility, nature, desirability and implications of various possible versions of immortality were at the forefront of the recently completed Immortality Project, a three-year, $5.1 million research initiative headed by University of California, Riverside philosopher John Martin Fischer and funded by the John Templeton Foundation. Using a competitive international evaluation system, the project funded 34 projects related to scientific, philosophical, and theological questions that touch on immortality, enabling the production of books and articles by scientists and humanists, popular writings, documentary films, and even works of science fiction. As a follow-up to the project, the Templeton Foundation recently commissioned a research review summarizing the current state of thinking on the scientific, philosophical, and theological intricacies of immortality, showing where the Immortality Project has moved the discussion forward — and highlighting areas ripe for future work.


A person thinking about immortality and the possibility of life after death.

Illustration created by James O’Brien

Much of the Immortality Project’s research addresses the chances of technological or medical breakthroughs that might greatly extend human lifespan and investigating non-human species that have atypical lifespans or aging. This research is directly relevant to the physiological or ‘staying alive’ conception of immortality. Project grantee Jon Cohen published “Death–defying experiments,” an article in Science cataloguing recent experiments in non-human species, including cases where mice and insects have achieved impressive ages. One particular mouse, GHR-KO 11C, lived nearly five years (about twice the normal mouse lifespan) thanks to the removal of a gene for a growth hormone receptor. Other insects and worms, such as the Caenorhabditis elegans, can have extended lives because of gene mutations. The biological champion of non-aging is the freshwater hydra, Hydra vulgaris, a tiny relative of corals and jellyfish that is the only species that doesn’t seem to age. In one case hydras were observed for ten years without signs of decay. Such studies suggest how anti-aging technologies might be developed for humans, although the journey from a hydra to a human would likely be a long one.

Other grants under the Immortality Project looked at the scientific evidence stemming from near-death and out-of-body experiences — and what it tells us both about the possibility that human existence might continue independent of our physical bodies and about the psychological importance of near-death experiences. Under the grant, physician Sam Parnia published the book-length Erasing Death, focusing on the biology of near-death experiences in specific patients, and ending with a call for greater investment in resuscitation science.

In a separate book, Near Death Experiences: Understanding Visions of the Afterlife, Fischer and Immortality Project postdoc Benjamin Mitchell-Yellin examine how supernaturalists have used near death experiences to bolster their arguments, although the authors conclude that such experiences do not provide particularly strong evidence that an immaterial soul that can become immortal.


Why is the idea of immortality so fascinating across so many human cultures? One common explanation for the prevalence of belief in some form of immortality is that it offers an alternative to the “existential terror” engendered by  contemplating potential non-existence after death for ourselves or other people. Several grantees under the project took up the contention of the Epicurean philosopher Lucretius that it is no more rational to worry about one’s non-existence after death than to worry about one’s non-existence prior to birth. Ben Bradley of Syracuse University examines several potential defenses of the idea that not existing is categorically bad — for instance, because it may deprive us of potential good we might have experienced by living longer — but finds them them unconvincing. As part of a multi-part subgrant examining “Time Bias and Immortality,” Notre Dame philosopher Meghan Sullivan suggests that Lucretius was not correct to argue that rationality requires we have symmetrical feelings about pre-life and post-life non-existence.

Sullivan’s work on this so-called ‘time bias’ also touched on another set of common philosophical questions on whether individual immortality could be either possible or good: for instance, would an immortal afterlife entail abrupt or gradual changes such that at some point an individual would fully cease to be themselves? And if they have ceased to be themselves, do they truly live on?

Another classic objection to the desirability of immortality is that over infinite time it would eventually become tedious. In Fischer and Mitchell-Yellin’s “Immortality and Boredom,” the project leaders argue that this objection is not well founded. Even if an immortal person were to exhaust all previously known experiences, new ones might still be created, and familiar ones could still be enjoyed.

Not all conceptions of immortality need to involve the persistence of a physical body or even a soul — one can talk about achieving immortality by having one’s work or values persist after death. In one grant-funded article, “The Immortals in Our Midst,” political philosophers Ajume Wingo and Dan Demetriou suggest that leaders who establish legacies of democratic values achieve a kind of “civic immortality” that may be the best method for bringing democratic values to countries that are not comfortable with western approaches to politics.

The Immortality Project also provided funding for U.C. Riverside philosopher Eric Schwitzgebel to publish several works of short fiction that used narrative to elaborate on the sort of spare thought experiments more typical in the philosophy of immortality. In “Reinstalling Eden: Happiness on a Hard Drive” and “Out of the Jar,” Schwitzgebel explores the ideas of simulated universes, full-body replication and pervasive artificial intelligence relate to the possible natures of immortality.


Many religions, and Christianity in particular, hold that believers will come experience some form of ‘eternal life.’ This is usually understood in terms of living on forever after death — often in the bliss of heaven or the torments of hell. However, Mikel Burley, a professor of religion and philosophy at the University of Leeds, argues that the eternal life promised to Christians need not exist only in the hereafter. Instead, eternal life may be realized during a believer’s lifetime on earth. Burley proposes that eternal life may be enjoyed as a “present possession,” appealing to four-dimensionalist metaphysics, which understands time as a fourth dimension akin to the three spatial dimensions. According to four-dimensionalism, ‘parts’ of time are as real as ‘parts’ of space, so that all times — past, present, and future — are equally real and exist eternally, just as all locations defined by the three spatial dimensions (height, width, and depth) also coexist. On Burley’s model, partaking of eternal life requires more than us simply existing eternally within time slices of our own past, present, and future: it requires that believers undergo a moral transformation wherein they come to participate in the life of God.

Christina Van Dyke of Calvin College used an Immortality Project subgrant to investigate the concept of sempiternity —a state of changeless duration without end — as described by Thomas Aquinas. She examines whether shifting to such a radically different temporal framework would necessarily change what it means to be human — or whether it would be an extension of already-known types of human experience, including the “timelessness” aspect of some mystical experiences, or the way perception of time changes for people engaged in creative “flow.”

Whatever temporal form eternity takes, should believers expect to spend it all in one (very good or very bad) place? Two grant-funded articles take up the belief in the intermediate and temporary eternal states of limbo or purgatory, which are most famously expounded in Catholic theology. Kevin Timpe’s “An Argument for Limbo” explores the concept as a state as an opportunity for individuals never given sufficient opportunity to accept God’s offer of redemption during their terrestrial life, including the cognitively disabled lacking the intellectual capacities, to be reconciled to God. Meanwhile, Joshua Thurow’s “Atoning in Purgatory” suggests that an omnibenevolent being such as God would want to bring about the most good and thus save the most amount of people; so giving people a chance in purgatory to right their wrongs so that they could enter heaven is in keeping with that goal.


Befitting a subject that touches on the neverending, the aggregate work produced by the Immortality Project identified many questions ripe for future exploration. Biological investigations quickly turn up profound ethical questions about how and to whom life-extending treatments might be made available — and how society might be altered if death became optional for some of its members. These ethical discussions involve the contemplation of thought experiments and imagined scenarios, raising additional meta-questions for investigation: Are such methods reliable ways to attain knowledge about immortality? Might fiction be more effective in this regard than abstract philosophizing, as Schwitzgebel suggests? What role do non-physical sciences such as psychology, sociology, anthropology, economics, or history have in helping us understand immortality?

One of the important collective outputs of the Immortality Project has been as a model of ways that interdisciplinary approaches can serve as a case study in scientific and scholarly communication. With a topic as emotionally and ethically vexatious as immortality, the chances of immortality research being misunderstood or misappropriated seem high, making it a perennial challenge for scholars and scholarly communities to better communicate their conclusions for a fascinated public.


Project researchers also helped advance our understanding of whether immortality is possible, and if so, under what conditions or scenarios.

Cohen, “Death Defying Experiments”

The possibility of extending biological lifespans has been the subject of many recent experiments in nonhuman species. In “Death-Defying Experiments” (2015), Jon Cohen writes about a variety of cases where mice and insects have achieved long lives. One tried and true method for extending lifespan is to limit animals’ food intake. One particular mouse, GHR-KO 11C, lived nearly five years (about twice the normal mouse lifespan) thanks to the removal of a gene for growth hormone receptor. Other insects and worms, such as the Caenorhabditis elegans, can have extended lives because of gene mutations. Yet despite these achievements in prolonged aging, Hydra vulgaris is the only species that shows no sign of aging. Unlike the other cases, Hydra has a unique ability to regenerate its stem cells through a gene called FoxO and after 10 years of observation there is no sign of decay or aging. Such studies suggest how anti-aging technologies might be developed for humans, technologies that could increase our lifespan many times over and perhaps even confer upon us a form of medical immortality.

Davis, “Four Ways Life Extension Will Change Our Relationship with Death”

Although genuine immortality—a condition in which it is actually impossible for us to die from any cause—seems farfetched, a time may come in the not-too-distant future when advances in biology and medicine allow us to extend our lives far beyond our current life expectancy by either slowing or halting our aging process. That means “we will remain youthful longer.” John Davis, in “Four Ways Life Extension Will Change Our Relationship with Death” (2016), articulates the ways that such 19 “radical” life extension will change our relationship with death. According to Davis, life extension will most likely be made possible by pharmacological interventions that affect our “cellular and molecularlevel processes.” Moreover, such interventions will not be a one-time occurrence but will require regular intake of drugs; that is, once we go off our anti-aging medications, our aging process would resume.

Davis considers the implications of radical life extension for four different populations. The first, group one, are those who have undergone life extension. According to Davis, group one’s condition would have five surprising consequences:

(1) Aging and death would be elective.

(2) They could forgo medications if they want to resume aging.

(3) Their deaths “will be unscheduled.”

(4) Their “life expectancy will always be the same.”

(5) Death would deprive them of more life than it would those that had the former, shorter lifespans.

In group two are those whose deaths might be made worse by the fact that they cannot get life extension. And death is worse for them because in a world in which life extension exists, they would be missing out on a great many years of life. Davis calls this the “death burden” argument. In the third group are those who “can get life extension but turn it down.” Their death benefits of “aging normally and dying on a normal biological schedule will be reduced somewhat even if, by turning down life extension, they age and die normally.” One benefit that aging affords us is allowing us to come to terms with our death. Life extension, however, takes that away from us since we would not age. Or in the case of group three, the mere fact that they could change their mind and get life extension means that they might not take their mortality as seriously as when life extension was not available. The fourth group consists of those “who can get life extension but prefer not to have it.” The members of the fourth group see themselves in a dilemma between choosing an unwanted life extension and what “they consider an immoral kind of suicide.” Davis’s research illustrates how even significant increases in lifespan that fall well short of immortality as it has traditionally been conceived would nevertheless greatly alter our relationship with our inevitable mortality and the significance of death itself.

Parnia and Young, “Erasing Death”

In “Erasing Death” (2013), Sam Parnia outlines an amazing story about Joe Tiralosi and his experience with death after suffering cardiopulmonary arrest. A specialized medical team provided Tiralosi with chest compressions, and after several minutes, doctors “hit Tiralosi’s body with an electric shock,” which continued for ten minutes. However, after ten minutes without a heartbeat, damage to the brain from a lack of oxygen starts to become permanent, and “without a properly functioning brain, Joe Tiralosi would no longer be Joe Tiralosi at all.” Nevertheless, doctors persisted in attempting 20 to resuscitate Tiralosi. Remarkably, the resuscitation continued for forty minutes, at which point the doctors and nurses unexpectedly detected Tiralosi’s pulse. Doctors discovered that Tiralosi had “a number of blockages in the vessels to his heart” after his second death, which lasted for fifteen minutes, and treated him with a common balloon procedure. Joe Tiralosi recovered well and returned home to his family and continued to live a normal, happy life. Parnia’s research concerned “optimal cardiac arrest care—the kind of medical science that saved Tiralosi—and into the experiences of consciousness people report bringing back from the other side of death after their hearts have been restarted.” While his heart had stopped, Tiralosi underwent what could be classified as a near-death or out-of-body experience. Tiralosi reported seeing a luminous being that made him feel fearless about death. For Parnia, Tiralosi’s case highlights the advancements that resuscitation science has made and raises philosophical and personal questions about our deaths. Parnia believes that resuscitation science could be the answer to reversing death.

Fischer and Mitchell-Yellin, “Near-Death Experiences: Understanding Visions of the Afterlife”

From the standpoint of debates about immortality, near-death experiences are significant because many take them to be decisive evidence in favor of both dualism (that human beings have immaterial souls as well as bodies) and a supernatural realm for which human beings are destined after death. Near-death experiences are thus a central point of contention between physicalist and supernaturalist conceptions of human nature and of the universe. John Martin Fischer and Benjamin Mitchell-Yellin (2016) carefully consider how supernaturalists have used near-death experiences to bolster their case. They conclude that such experiences do not provide particularly strong evidence for supernaturalism or for an immaterial soul that can survive death and become immortal. Fischer and Mitchell-Yellin argue that most all the common features of near-death experiences (a sensation of floating away, encounters with God and with deceased loved ones, recollections of events while the individuals were unconscious, etc.) either do or could have naturalistic explanations, and the testimony of near-death experiences is also subject to significant confirmation bias. Cholbi’s review of Fischer and MitchellYellin (2017) argues that the cultural congruence of the details of near-death experiences (bright lights, etc.), along with the absence of negative or frightening near-death experiences, suggest that the testimony of near-death experiencers, while sincere, is likely to be unreliable and highly influenced by culturally specific tropes and expectations. Cholbi also notes that some of the most high-profile neardeath narratives were later recanted or cast into doubt thanks to credibility issues on the part of the narrators. In the end, Fischer and Mitchell-Yellin deny that near-death experience is metaphysically significant, but they affirm that it is ethically significant, inasmuch as such experiences are often life transforming and offer inspiring utopian visions of social harmony and peace.


Together, Near-Death Experiences and Cholbi’s review offer an evenhanded investigation of a set of experiences that have been the subject of intense popular interest. They invite readers to be skeptical of the more extravagant or unexamined claims put forth by near-death experience enthusiasts while approaching the phenomenon with a seriousness that those with a dismissive attitude toward neardeath experiences often do not display. In this respect, this research exemplifies the critical scrutiny of immortality that the Project was meant to encourage. 21

Schwitzgebel, “Reinstalling Eden: Happiness on a Hard Drive” and “Out of the Jar”

Given that mortality is a central feature of the human condition, it is hardly surprising that immortality, its conditions, and its consequences have been an enduring theme in imaginative literature. In his short stories “Reinstalling Eden: Happiness on a Hard Drive” and “Out of the Jar,” Eric Schwitzgebel considers the prospect that we humans live in an elaborate simulation. “Out of the Jar” imagines the interactions between a suburban professor who is part of a video game–like computer simulation run by an angry God-like teenager. The professor appears in various scenes as a psychopathic killer, a policeman, and a dinosaur. “Out of the Jar” seems to envision a kind of digitized immortality in which a bored, irritable deity treats humanity as its playthings. Likewise, in “Reinstalling Eden,” Schwitzgebel describes a scientist creating conscious versions of Adam and Eve in a computer. Schwitzgebel believes that fiction and novels can have greater impact on popular thinking about subjects such as immortality than more conventional academic scholarship. His own stories, which investigate artificial intelligence, identity, and other metaphysical questions related to survival and immortality, offer an alternative, and perhaps more accessible, path into these questions.


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