Which is more feasible, digital immortality or biological immortality?

Before answering this question, we need to figure out -

Why is there a limited lifespan for human beings?

Until the 60s of the 20th century, it was believed that vertebrate cells had the ability to divide indefinitely. It wasn't until 1961 that the discovery of American microbiologist Leonardo Haverick shattered people's illusions.

Through experimental observation, Hayflick found that there is an upper limit of 40~60 times for the number of divisions of normal cells in vitro. This upper limit is also known as the Hayfrick limit [1].

In the 70s of the 20th century, scientist Elizabeth Blackburn and others discovered the telomere structure located at the end of chromosomes.

Human telomeres

Telomeres protect chromosomes and ensure the stability of genes during replication, but telomeres lose some of them each time they replicate. When the lost telomeres reach their limit, the cell no longer divides [2].

The discovery of telomeres perfectly explains the Hayfrick limit.

Elizabeth Blackburn and others have also discovered telomerase, which repairs telomeres.

Telomerase molecular structure

The order in which telomeres are made by telomerase and DNA polymerase

The length of the Hayfrick limit in different cells is limited by the length of the telomeres of the cells, as well as the ability to repair. The Hyflick limit for pancreatic islet cells is only more than 10 times, while the Hayfrick limit for hematopoietic stem cells can reach more than 100 times.

After entering the 21st century, the study of telomeres has become a popular field of biology. In 2009, Elizabeth Blackburn et al. were awarded the Nobel Prize in Physiology or Medicine [3].

Can telomeres repaired with telomerase break the Hayfrick limit?

The reason why embryonic stem cells and germ cells can divide indefinitely is because of the repair of telomeres with telomerase. However, in normal cells, if telomerase is too active, it can lead to the development of cancer. The reason why cancer cells can divide indefinitely is also because of the infinite repair of telomeres by telomerase.

Is it possible to break through the Hyfrick limit without increasing the incidence of cancer?

This is possible, around 2000, researchers introduced exogenous telomerase to repair (ectopic expression) of cell chromosomal telomeres [4] [5], creating immortal cell lines without cancer. The ectopic expression of telomerase has a broad application prospect and may even provide a solid foundation for human immortality technology in the future.

In the distant future, it is not impossible to use the ectopic expression of telomerase to achieve immortality.

For example, among invertebrates, many animals have an infinite theoretical lifespan, such as hydras, lobsters, etc., and lobsters are typical of having the ability to repair telomeres indefinitely.

But it's not just telomeres that limit eternal life.

In 2013, an article titled "The hallmarks of aging" was published in the journal Cell, which provided a series of classic summaries of human aging research [6].

In addition to telomere loss, genomic instability, epigenetic changes, protein homeostasis imbalance, nutrient induction dysregulation, mitochondrial dysfunction, cellular senescence, stem cell depletion, and altered cell-to-cell communication are enumerated.

Nine factors influence each other and together determine the aging of the human body, but it is the genetic level that plays a decisive role.

But fundamentally speaking, it is actually the irreversible accumulation of damage/damage from the microscopic level of cells and molecules over the past few decades.

Human cells reach 100 trillion, and 330 billion are updated every day, and it is an astronomical amount to repair at the cellular and molecular level, not to mention the difficulty, in terms of total workload.

The fundamental problem of immortality technology is like a moat in front of mankind.

It is also under this premise that many people regard digital immortality as an alternative to biological immortality.

Can digital immortality really be achieved as an alternative to biological immortality?

The premise of digital immortality in the true sense of the word (not just electronic data backup) is to be able to achieve true consciousness uploading.

However, before consciousness can be uploaded, one must face a question that cannot be fully answered today:

What exactly is consciousness?

Higher-order theories (HOTs), global workspace theories (GWT), information integration theory (IIT), and re-entry and predictive processing theories are the four main theories that explain consciousness, but embarrassingly, none of these theories can be truly verified at present.

Even because there are too many people who believe it, the Information Integration Theory (IIT) has been "blindly" labeled as "pseudoscience" by 124 scientists [7].

But in fact, we can also ignore the controversy over the theory of consciousness, at least in the 100 years since the development of neuroscience, there are some basic consensus:

Consciousness is generally regarded as a material and physiological function of the brain.

While we don't quite figure out what consciousness actually is, some experiments have at least shown that consciousness cannot be separated from the material basis of the brain.

As early as the 80s of the 20th century, psychologist Benjamin Libett conducted a famous experiment [8] [9].

They sat 5 left-handed college students on a recliner and told them to relax their head, neck, and forearm muscles for 1~2 seconds. But before they decide to do this one, they need to move a finger or wrist suddenly and quickly. When they move their fingers, don't have any pre-planned or deliberate attention, repeat 40 times randomly.

When these college students performed these movements, the researchers measured three variables:

1. Stick the electrodes on the forearm and record the time when the finger action begins.

2. Electrodes attached to the scalp to test the brain's preparatory potential at the beginning of the movement.

3. When you feel the impulse to act (want to move your fingers), shout out the "time" of the clock on the screen, so as to measure the moment of decision.

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After hundreds of experiments, Libett finally discovered that the moment of decision came after the brain's preparatory potential.

The average time interval is 350ms.

In other words, 1/3 of a second before we decide to do something, the brain is already initiating.

Therefore, some researchers are pessimistic that human beings do not have free will.

However, in a further experiment, Libett asked the college students to veto the behavior after making a decision.

Although the brain had a preparatory action potential, it eventually stopped the action and the potential in the hand was not detected. In recent years, studies have further shown that the success rate of veto can be greatly reduced when the brain action potential appears within a certain period of time, but when it is close enough to the action time [10].

This shows that whether human beings have free will or not, they have the freedom to veto for a certain period of time.

For 40 years, there has been a great deal of research to support the results of Libett's experiments in which consciousness is determined by the effects of brain action. The delay time can be as short as hundreds of milliseconds and as long as more than 10 seconds [11] [12] [13].

In one experiment, transcranial magnetic stimulation altered the subject's left and right hand habits, and the subject still believed that his choice was made by free will [14]. Under some experimental designs, subjects may also assume that their own decision-making behavior occurs when unconscious judgment or impulsive behavior occurs [15].

Direct stimulation of the higher cortex may result in incorrect conscious judgments. For example, they may think they are doing something but it didn't happen [16].

This seems to reinforce the affirmation that human beings do not have free will.

However, in the last 10 years or so, some researchers have made further discoveries, and some researchers have rejected the idea that human beings do not have free will.

In 2009, someone modified Libett's classic experiment to play an audio clip and then asked volunteers to decide whether to hit a key. The study found that regardless of whether the volunteers actually chose to tap, there was the same brain preparation potential in both cases.

This suggests that the brain preparation potential does not indicate that a decision has been made.

Of course, when the volunteers immediately decided whether to use their left or right hand to press the buttons, there was no difference in the early action potentials of the brain, suggesting that the early action potentials produced by the brain may be noticing signals or pre-processing information.

In recent years, there have been more and more precise methods to prove that conscious decisions do not occur instantaneously, but are built up gradually. Therefore, some researchers have suggested that the early neural markers of decision-making outcomes are not unconscious, but simply reflect the conscious goal assessment stages, which are not yet final, and that the decision can be terminated or changed before the final conscious activity is reached [17].

In short, the fact that an action may have started before our "consciousness" realizes it does not mean that our consciousness cannot approve, modify or cancel the action.

These experiments allow us to make the following judgments without talking about specific theories of consciousness:

Consciousness is the product of the brain's neural activity, it has no prerequisites, and it cannot exist alone. There is no single piece of information (or even a quantum state of consciousness/soul) that can be used to upload consciousness.

To achieve true consciousness uploading, it is essentially necessary to maintain the continuity of consciousness.

The good news is that the continuity of consciousness can be maintained through the continuity of matter.

The substance of our brain, as we grow up, is itself a process of continuous change, and the microstructure is constantly replaced. Our autobiographical memories maintain a continuous stream of changes in our consciousness and self-awareness, allowing us to consciously experience and experience ourselves.

And this continuously changing information, which is the thousands of electrochemical processes, can be replicated or replaced by electronic hardware.

In other words, in order to achieve true consciousness uploading, then it is necessary to create truly replaceable electronic neurons, and then gradually replace the neurons as a person grows up to maintain the continuity of autobiographical memory, so that consciousness can be truly uploaded.

In other words, digital immortality in the true sense of the word requires equivalent replacement at the cellular level, which requires human molecular nanorobotics technology to reach an extremely high level.

As mentioned earlier, at the biological level, the reason why human beings cannot live forever is that the nine reasons mentioned above (genomic instability, epigenetic changes, imbalance in protein homeostasis, dysregulation of nutrient induction, abnormal mitochondrial function, cellular senescence, and stem cell depletion) are essentially reflected in a kind of accumulation of destruction.

With such a high level of nanorobotics technology, it is fully capable of repairing damage at the molecular level, anytime, anywhere.

Not only can people live forever, but even can truly maintain eternal youth, so that the biological age is maintained in a constant situation.

In other words, it is quite possible that true digital immortality is based on the premise that biological immortality has already been achieved.

Naturally, it loses its vicarious meaning when the immortality of living beings is impossible. Like the digital man in the movie "The Wandering Earth 2", I would rather call it an electronic replicant than a digital immortal in the true sense.

When you achieve biological immortality, there are a large number of controllable nanobots in your body at all times.

Human cells reach 100 trillion, even 1% is 1 trillion nanorobots.

The precise control of all nanorobots requires at least one supercomputer to maintain, and requires excellent artificial intelligence algorithms that match the human body that does not exist today.

This comes at a very high cost to the continued maintenance of any person's eternal life.

And in order to better match the machine, human body modification is inevitable. Coupled with the fact that the maintenance cost of machines is likely to be lower than that of organisms, more people may choose to replace their bodies with machines in the future.

With the development of the times, quantitative change to qualitative change. The boundaries between biological and digital immortality are likely to become increasingly blurred, and eventually lead to the same end.

In this case, the morphology of the organism can even be designed freely.

So, at the end of the day, can we come up with a hypothesis like this:

Regardless of how life/civilization originated, the ultimate life forms in the universe will have very little difference in matter. The biggest difference may simply be in cultural differences, individual/group preferences for the appearance of life.

The above parts that go beyond the existing theories are all personal opinions.

Feel free to discuss in the comment section.

reference

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2. ^Blackburn E H. Switching and signaling at the telomere[J]. Cell, 2001, 106(6): 661-673.
3. ^https://www.nobelprize.org/prizes/medicine/2009/summary/
4. ^Counter C M, Meyerson M, Eaton E N, et al. Telomerase activity is restored in human cells by ectopic expression of hTERT (hEST2), the catalytic subunit of telomerase[J]. Oncogene, 1998, 16(9): 1217-1222.
5. ^Hooijberg E, Ruizendaal J J, Snijders P J F, et al. Immortalization of human CD8+ T cell clones by ectopic expression of telomerase reverse transcriptase[J]. The Journal of Immunology, 2000, 165(8): 4239-4245.
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