Immortality



Immortality (or eternal life) is the concept of living in physical or spiritual form for an infinite length of time As immortality is the negation of mortality—not dying or not being subject to death—it has been a subject of the greatest fascination to mankind since at least the beginning of history. The Epic of Gilgamesh, one of the first literary works, dating back at least to the 22nd century BC, is primarily a quest of a hero seeking to become immortal. What form an unending human life would take, or whether the soul exists and possesses immortality, has been a fundamental point of focus of philosophy and religion, as well as the subject of speculation, fantasy, and debate.

As of May 2008, human physical immortality is not known to be an achievable possibility. Biological forms have inherent limitations in their design — for example, their fragility and slow adaptability to changing environments. Michael Shermer believes there is no significant scientific evidence for the proposed methods of achieving physical immortality, and says of them, "All have some basis in science, but none has achieved anything like scientific confirmation." Jacques-Yves Cousteau, in the preface to his book The Ocean World, expressed his meditations on physical immortality, as a part of life and its adaptive processes: "Death is fundamental to evolution," and "evolution is fundamental to survival." Cousteau concludes that, biologically speaking, "immortality does not present a possible means to avoid death... Mortal or immortal, an [organism] must die."

A timeless existence is also not known for certain to be achievable, or even definable, despite millennia of arguments for eternity. Wittgenstein, in a notably non-theological interpretation of eternal life, writes in the Tractatus that, "If we take eternity to mean not infinite temporal duration but timelessness, then eternal life belongs to those who live in the present."

Spiritual

 * The belief in an afterlife experienced by an immortal soul is a dogma of many branches of Christianity, Zoroastrianism, Hinduism, Islam, and Judaism. This belief is related to the philosophy of dualism.

Christian belief is that [spirits] never die only our bodies and souls go to the grave and will be raised in God own order. Eternal life or eternal damnation is the choice that mankind will have to make.

Hypothetical

 * Fame itself has been described as a method to "achieve immortality", if only semantically, so that the name or works of a famous individual would "live on" after his or her death. This view of immortality places value on how one will be remembered by generations to come. For example, in Homer's Iliad, Achilles is already nigh-invincible, so his primary motive for fighting in the Trojan War is recognition and everlasting fame.
 * Mystic approaches to immortality include those of the ancient Chinese Taoists and European medieval alchemists, seeking an elixir of life.
 * Should metaphysical universals and abstract phenomena have an eternal existence, and if they can be interacted with by human beings, then a person might obtain a degree of immortality by interacting with them.
 * Quantum immortality is not widely regarded by the scientific community as being a verifiable or even necessarily correct offshoot of the many worlds interpretation. In the many worlds interpretation of quantum mechanics, the wavefunction never collapses, and thus all possible outcomes of a quantum event exist simultaneously, with each event apparently spawning an entirely new universe in which a single possible outcome exists. In this theory, a person could hypothetically live forever as there might exist a string of possible quantum outcomes in which that individual never dies.

Physical

 * The persistence of life itself across time is a form of immortality, insofar as leaving surviving offspring or genetic material is a means of defeating death. Sociobiology and Richard Dawkins' theory of the selfish gene are related to this understanding of immortality.
 * Life extension technologies promise a path to complete rejuvenation. Cryonics holds out the hope that the dead can be revived in the future, following sufficient medical advancements.
 * Mind uploading is the concept of transference of consciousness from a human brain to an alternative media providing the same functionality. Assuming the process to be possible and repeatable, this would provide immortality to the consciousness, as predicted by futurists such as Ray Kurzweil.

Physical immortality
Physical immortality is a state of life that allows a person to avoid death and maintain conscious thought, though it can mean the unending existence of a person from a physical source other than organic life, such as a computer. In the early 21st century, physical immortality remains a goal rather than a current reality. Active pursuit of physical immortality can either be based on scientific trends, such as predictions of an impending technological singularity, or because of a spiritual belief, such as those held by Rastafarians or Rebirthers.

Causes of death
By definition, all causes of death must be overcome or avoided for physical immortality to be achieved. There are three main causes of death: aging, disease and trauma.

Aging
Aubrey de Grey, a leading researcher in the field, defines aging as follows: “a collection of cumulative changes to the molecular and 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), oncogenic nuclear mutations and epimutations, cell senescence, mitochondrial 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.

Disease
Disease is theoretically surmountable via technology. Human understanding of genetics is leading to cures and treatments of a myriad of previously incurable diseases. The mechanisms by which other diseases do their 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 and 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. Vaccines 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 myriad other diseases and ailments.

Trauma
Physical trauma would remain as a threat to perpetual physical life, even if the problems of aging and disease were overcome, as an otherwise immortal person would still be subject to unforeseen accidents or catastrophes. Ideally, any methods to achieve physical immortality would mitigate the risk of encountering trauma. Taking preventative measures by engineering inherent resistance to injury is thus relevant in addition to entirely reactive measures more closely associated with the paradigm of medical treatment.

The speed and quality of paramedic response remains a determining factor in surviving severe trauma. A body that could automatically treat itself from severe trauma, such as speculated uses for nanotechnology, would mitigate this factor.

Being the seat of consciousness, the brain cannot be risked to trauma if a continuous physical life is to be maintained. Therefore, it cannot be replaced or repaired in the same way other organs can. A method of transferring consciousness would be required for an individual to survive trauma to the brain, and this transfer would have to anticipate and precede the damage itself.

Biological immortality


Biological immortality is an absence of aging, specifically 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.

Biologists have chosen the word immortal to designate cells that are not limited by the Hayflick limit, where cells no longer divide because of DNA damage or shortened telomeres. Prior to the work of Leonard Hayflick there was the erroneous belief fostered by Alexis Carrel that all normal 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. 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.

Biologically immortal species
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:

Recent research, however, suggests that even bacteria as a colony may eventually die since each succeeding generation is slightly smaller, weaker, and more likely to die than the previous.
 * Bacteria (as a colony) — Bacteria reproduce through cell division. A parent bacterium splits itself into two identical daughter cells. These daughter cells then split themselves in half. This process repeats, thus making the bacterium colony essentially immortal.
 * Hydra can be considered biologically immortal as they do not undergo senescence or aging.
 * Turritopsis nutricula, a jellyfish, after becoming a sexually mature adult, can transform itself back into a child (the polyp stage) using the cell conversion process of transdifferentiation. Turritopsis nutricula repeats this cycle, meaning that it may have an indefinite lifespan.
 * Bristlecone Pines are speculated to be potentially immortal; the oldest known living specimen is over 4800 years old.

Evolution of aging
As the existence of biologically immortal species demonstrates, there is no thermodynamic necessity for senescence: a defining feature of life is that it takes in 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 teleomere "end replication problem" are found even the earliest and simplest of organisms. This may be a tradeoff between selecting for cancer and selecting for aging.

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.

Antagonistic pleiotropy is a theory proposed as an alternative by 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.

The disposable soma theory was proposed in 1977 by 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.

Technological immortality


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. 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 nanorobots could be created to go through human bloodstreams, find dangerous things like cancer cells and bacteria, and destroy them. Freitas anticipates that gene-therapies and nanotechnology will eventually make the human body effectively self-sustainable and capable of living indefinitely, short of severe trauma. This supports the theory that we will be able to continually create biological or synthetic replacement parts to replace damaged or dying ones.

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, is the answer for those who believe that nanotechnology or nanorobots 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 aging is reversible. Modern cryonics procedures use a process called 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 brain structure. Many people who wish to become physically immortal think of cryonics as a backup plan in case the emerging life extension technologies don't develop rapidly enough.

Mind-to-computer uploading
One interesting possibility involves uploading the personality and memories via direct mind-computer interface. Extropian futurists have proposed that, thanks to exponentially growing computing power, it will someday be possible to upload human consciousness onto a computer system, and live 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. Gradually more and more components would be added until the person's entire brain functions were handled by artificial devices, without any sharp transitions that would lead to some identity issues mentioned below. At this point, the human body would become only an accessory and the mind could be transferred to any sufficiently powerful computer. A person in this state would then be essentially immortal, short of cataclysmic destruction of the entire civilization and their computers.

However, other futurists argue that it is impossible to truly move one's consciousness from one body to another; it could be duplicated, but the original would still exist, creating two independent consciousnesses. Uploading is still only a hypothesis and has no scientific backing or proof that it is possible.

Cyborgology
Transforming a human into a cyborg can include brain implants or extracting a human mind and placing it in a robotic life-support system. Even replacing biological organs with robotic ones could increase life span (ie 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. Such modifications would make one impervious to aging and disease and theoretically immortal unless killed or destroyed.

Mystical and religious pursuits of physical immortality
Many Indian fables and tales include instances of metempsychosis — the ability to jump into another body — performed by advanced Yogis in order to live a longer life. There are also entire Hindu sects devoted to the attainment of physical immortality by various methods, namely the Naths and the Aghoras.

Long before modern science made such speculation feasible, people wishing to escape death turned to the supernatural world for answers. Examples include Chinese Taoists and the medieval alchemists and their search for the Philosopher's Stone, or more modern religious mystics such as Sri Aurobindo, who believed in the possibility of achieving physical immortality through spiritual transformation. In 18th century France, a man who called himself the Comte de Saint-Germain claimed to be centuries old; people who adhere to the Ascended Master Teachings are convinced of his physical immortality.

Rastafarians believe in physical immortality as a part of their religious doctrines. They believe that after God has called the Day of Judgment they will go to what they describe as Mount Zion in Africa to live in freedom for ever. They avoid the term "everlasting life"' and deliberately use "ever-living" instead.

Another group that believes in physical immortality are the Rebirthers, who believe that by following the connected breathing process of rebirthing they can physically live forever.

Religious traditions
Until the late 20th century, there were no creditable scientific forecasts that physical immortality was obtainable. As late as 1952, the editorial staff of the Syntopicon found that in their compilation of the Great Books of the Western World, "The philosophical issue concerning immortality cannot be separated from issues concerning the existence and nature of man's soul." Thus, the vast majority of speculation regarding immortality before the 21st century was regarding the nature of the afterlife.

Spiritual immortality, also known as the immortality of the soul, is the unending existence of a person from a nonphysical source, or in a nonphysical state, such as a soul.

It is a belief that is expressed in nearly every religious tradition. In both Western and Eastern religions, the spirit is an energy or force that transcends the mortal body, and returns to: (1) the spirit realm whether to enjoy heavenly bliss or suffer eternal torment in hell, or; (2) the cycle of life, directly or indirectly depending on the tradition.

The world's major religions hold a number of perspectives on spiritual immortality.

Hinduism
Hindus believe in an immortal soul which is reincarnated after death. According to Hinduism, people repeat a process of life, death, and rebirth in a cycle called samsara. If they live their life well, their karma improves and their station in the next life will be higher, and conversely lower if they live their life poorly. Eventually after many life times of perfecting its karma, the soul is freed from the cycle and lives in perpetual bliss. There is no eternal torment in Hinduism, temporal existence being harsh enough, although if a soul consistently lives very evil lives, it could work its way down to the very bottom of the cycle.

Shintoism
Shintoists claim that except for those who choose or are dispatched to the underground world of Yomi, every living and non-living being may lose its body, but not its soul (tamashii), and that they live together with mortal souls as an immortal being called Kami. Shinto allows anything to attain Kami status regardless of its existence before becoming Kami. Therefore, even those that do not believe in Shinto may choose to become Kami, as well as things like a rock, a tree, or even a robot. Some may be reincarnated for various reasons.

Zoroastrianism
Zoroastrians believe that on the fourth day after death, the human soul leaves the body and the body remains as an empty shell. Souls would go heaven or hell; these concepts of the afterlife in Zoroastrianism may have influenced Abrahamic religions.

Buddhism
Buddhists believe that there is a cycle of birth, death, and rebirth and that the process is according to the qualities of their actions. This constant process of becoming ceases at the fruition of Bodhi (enlightenment) at which a being is no longer subject to causation (karma) but enters into a state that the Buddha called amata (deathlessness).

According to the philosophical premise of the Buddha, the initiate to Buddhism who is to be "shown the way to Immortality (amata)", wherein liberation of the mind (cittavimutta) is effectuated through the expansion of wisdom and the meditative practices of sati and samādhi, must first be educated away from his former ignorance-based (avijja) materialistic proclivities in that he "saw any of these forms, feelings, or this body, to be my Self, to be that which I am by nature".

Thus, desiring a soul or ego (ātman) to be permanent is a prime consequence of ignorance, itself the cause of all misery and the foundation of the cycle of reincarnation (saṃsāra). Form and consciousness being two of the five skandhas, or aggregates of ignorance, Buddhists believe that physical immortality is neither a path to enlightenment, nor an attainable goal: even the gods which can live for eons eventually die. Upon enlightenment, the "karmic seeds" (saṅkhāras or sanskaras) for all future becoming and rebirth are exhausted. After biological death an arhat, or buddha, enters into parinirvana, an everlasting state of transcendental happiness.

Judaism
Judaism claims that the righteous dead will be resurrected in the Messianic age with the coming of the messiah. They will then be granted immortality in a perfect world. The wicked dead, on the other hand, will not be resurrected at all. This is not the only Jewish belief about the afterlife. The Tanakh is not specific about the afterlife, so there are wide differences in views and explanations among believers.

The Hebrew Bible speaks about sheol (שאול), the underworld to which the souls of the dead depart. The doctrine of resurrection is mentioned explicitly only in although it may be implied in several other texts. Later Judaism accepted that there would be a resurrection of all men (cf. ) and the intertestamental literature describes in more detail what the dead experience in sheol. By the second century BC, Jews who accepted the Oral Torah had come to believe that those in sheol awaited the resurrection either in comfort (in the bosom of Abraham) or in torment.

Christianity
Christian theology holds that Adam and Eve lost physical immortality for themselves and all their descendants in the Fall of Man, though this initial "imperishability of the bodily frame of man" was "a preternatural condition."

According to the book of Enoch, the righteous and wicked await the resurrection in separate divisions of sheol, a teaching which may have influenced Jesus' parable of Lazarus and Dives. Christians believe that every person that believes in Christ will be resurrected; Bible passages are interpreted as teaching that the resurrected body will, like the present body, be both physical (but a renewed and non-decaying physical body) and spiritual.

Specific imagery of resurrection into immortal form is found in the Pauline letters:

Behold, I shew you a mystery; We shall not all sleep, but we shall all be changed,

In a moment, in the twinkling of an eye, at the last trump: for the trumpet shall sound, and the dead shall be raised incorruptible, and we shall be changed.

For this corruptible must put on incorruption, and this mortal must put on immortality.

So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory.

O death, where is thy sting? O grave, where is thy victory?

The sting of death is sin; and the strength of sin is the law.

But thanks be to God, which giveth us the victory through our Lord Jesus Christ.

Therefore, my beloved brethren, be ye stedfast, unmoveable, always abounding in the work of the Lord, forasmuch as ye know that your labour is not in vain in the Lord. —

In Romans 2:6-7 Paul declares that God "will render to every man according to his deeds: To them who by patient continuance in well doing seek for glory and honour and immortality, eternal life", but then in Romans 3 warns that no one will ever meet this standard.

After the Last Judgment, those who have been born again will live forever in the presence of God, and those who were never born again will be abandoned to never-ending consciousness of guilt, separation from God, and punishment for sin. Eternal death is depicted in the Bible as a realm of constant physical and spiritual anguish in a lake of fire, and a realm of darkness away from God. Some see the fires of Hell as a theological metaphor, representing the inescapable presence of God endured in absence of love for God; others suggest that Hell represents complete destruction of both the physical body and of spiritual existence.

Roman Catholicism
Roman Catholic dogmatic theology also used to teach that there is a supernatural realm called Purgatory where souls who have died in a state of grace but have yet to expiate venial sins or temporal punishments due to past sins are cleansed before they are admitted into Heaven.

Jehovah's Witnesses
Jehovah's Witnesses believe the word soul (nephesh or psykhe) as used in the Bible is a person, an animal, or the life a person or animal enjoys. Hence, the soul is not part of man, but is the whole man — man as a living being. Hence, when a person or animal dies, the soul dies, and death is a state of non-existence, based on Ezekiel 18:4. Hell (hades or sheol) is not a place of fiery torment, but rather the common grave of humankind, a place of unconsciousness.

After the final judgment, it is expected that the righteous will receive eternal life and live forever in an earth turned into a paradise. Another group referenced as "the little flock" of 144,000 people will receive immortality and go to heaven to rule as Kings and Priests. Jehovah's Witnesses make the distinction that those with 'eternal life' can die though they do not succumb to disease or old age, whereas immortal ones cannot die by any cause. They teach that Jesus was the first to be rewarded with heavenly immortality, but that Revelation 7:4 and Revelation 14:1, 3 refer to a literal number (144,000) of additional people who will become "self-sustaining," that is, not needing anything outside themselves (food, sunlight, etc.) to maintain their own life.

Mormonism
In Mormon theology, there are three degrees of glory which are the ultimate, eternal dwelling place for nearly all who lived on earth. Joseph Smith, Jr., the founder of the Latter Day Saint movement, provided a description of the afterlife based upon a vision he reportedly received, recorded within the Mormon canonical writings entitled Doctrine and Covenants. According to this section of LDS scripture, the afterlife consists of three degrees or kingdoms of glory, called the Celestial Kingdom, the Terrestrial Kingdom, and the Telestial Kingdom. The few who do not inherit any degree of glory (though they are resurrected) reside in a state called outer darkness, which, though not a degree of glory, is often discussed in this context. The only ones who go there are known as "Sons of Perdition".

Critics of the Latter Day Saint Movement argue that Joseph Smith used the ideas of Emanuel Swedenborg to formulate the theology surrounding the three degrees of glory.

Other Christian beliefs
The doctrine of conditional immortality states the human soul is naturally mortal, and that immortality is granted by God as a gift. The doctrine is a "significant minority evangelical view" that has "grown within evangelicalism in recent years".

Some sects who hold to the doctrine of baptismal regeneration also believe in a third realm called Limbo, which is the final destination of souls who have not been baptised, but who have been innocent of mortal sin. Souls in Limbo include unbaptised infants and those who lived virtuously but were never exposed to Christianity in their lifetimes. Christian Scientists believe that sin brought death, and that death will be overcome with the overcoming of sin.

Islam
Muslims believe that everyone has an immortal soul which will live on after death. A soul undergoes correction in Hell if it has led an evil life, but once this correction is over, the soul is admitted to Heaven. Souls that commit unforgivable evil will never leave hell. Some souls will therefore never taste Heaven.

Ethics of immortality
The possibility of clinical immortality raises a host of medical, philosophical, and religious issues and ethical questions. These include persistent vegetative states, the nature of personality over time, technology to mimic or copy the mind or its processes, social and economic disparities created by longevity, and survival of the heat death of the universe.

Undesirability of immortality
Essential to many of the world's religions is a doctrine of an eternal afterlife. Narratives from Christianity and Islam assert that eternal afterlife is not desirable to the unfaithful:

"The rich man also died, and was buried; And in hell he lift up his eyes, being in torments, and seeth Abraham afar off, and Lazarus in his bosom. And he cried and said, Father Abraham, have mercy on me, and send Lazarus, that he may dip the tip of his finger in water, and cool my tongue; for I am tormented in this flame. But Abraham said, Son, remember that thou in thy lifetime receivedst thy good things, and likewise Lazarus evil things: but now he is comforted, and thou art tormented. And beside all this, between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence."

- Luke 16:22-26 King James Bible Translation

"Those who are wretched shall be in the Fire: There will be for them therein (nothing but) the heaving of sighs and sobs: They will dwell therein for all the time that the heavens and the earth endure, except as thy Lord willeth: for thy Lord is the (sure) accomplisher of what He planneth. And those who are blessed shall be in the Garden: They will dwell therein for all the time that the heavens and the earth endure, except as thy Lord willeth: a gift without break."

- The Qur'an, 11:106-108

Instances from other religions include the Buddhist concept of eternal rebirth, which considers that rebirth is caused by ignorance, an essentially undesirable condition that is to be overcome.

Physical immortality has also been imagined as a form of eternal torment, as in Mary Shelley's short story "The Mortal Immortal", the protagonist of which witnesses everyone he cares about dying around him. Jorge Luis Borges explored the idea that life gets its meaning from death in the short story "'The Immortal"; an entire society having achieved immortality, they found time becoming infinite, and so found no motivation for any action.

Desirablity of immortality
Many religions promise their faithful an eternal paradise in an afterlife. These presume perfection, as they are part of a divine plan, and are categorically desirable.

Physical immortality is considered desirable over its counterpart, death, which to date has been inevitable for all human beings. This presumes tolerable living conditions as an incentive for perpetual life, as the prevalence of suicide demonstrates.

Symbols
There are numerous symbols representing immortality. Pictured here is an Egyptian symbol of life that holds connotations of immortality when depicted in the hands of the gods and pharaohs who were seen as having control over the journey of life, the ankh (left). The Möbius strip in the shape of a trefoil knot is another symbol of immortality. Most symbolic representations of infinity or the life cycle are often used to represent immortality depending on the context they are placed in. Other examples include the Ouroboros, the Chinese fungus of longevity, the ten kanji, the phoenix, and the colors amaranth (in Western culture) and peach (in Chinese culture).

Fiction
Immortal beings and species abound in fiction, especially fantasy fiction.