Immortality
We often speak of “...our immortal soul..”. This gives rise to the question of what “immortality” means. We cannot know how long the Universe will continue in existence, so a definition of “immortality” that makes reference to infinite time does not seem to make sense. A better definition of immortality would refer to the idea that the thing which is immortal could exist with no degradation in its essential characteristics so long as its environmental parameters remained reasonable. If the Sun becomes a supernova, then things on Earth that had been immortal up to that point then might cease to exist. Those things transferred to another region of space, with a more stable star system, could certainly survive the end of the Earth. If the Big Crunch occurs and the Universe collapses back to an atom like object of very high density, then it seems likely that all things thought to be immortal up to that point, would then lose their existence. Within those constraints, we can explore the concept of immortality.
What we know is that high energy, in the forms of high temperatures, high energy particle collisions, massive (meteoric) collisions and strong force fields such as electrical or gravitational tend to act in ways that limit the mechanical stability of things made of atoms. As a result, things made of atoms can only be expected to be immortal under benign environmental conditions. However, some parts of the Earth have been reasonably benign for billions of years. Thus a carefully designed, subterranean networked computer complex, that was geographically distributed, perhaps partly in lunar caverns, could expect to continue to function for billions of years. Massive volcanic activity such as that which produced the Deccan Traps in India, could wipe out all computer facilities in that area, but when something bad is happening somewhere, there have always been other parts of the Earth safe from disaster. Thus, it is reasonable to assume that some future generation should be able to find ways to implement computer systems able to operate autonomously with very long expected lifetimes, despite damage do to various local disasters and other sources of degradations. This might involve having computer systems that can make and geographically distribute additional computer systems. The Moon might be the ideal local for such futuristic systems.
Atoms come in two kinds, intrinsically stable and unstable. By stable, we mean that the expected lifetime is very long compared to the age of the universe. A good example would be an He3 (Helium 3) atom. On the other hand, an H3 (Hydrogen 3 or Tritium) atom is not stable, it decays with a half life of about 15 years. Atoms are little machines that are always working but never wear out. No matter how old an atom is, it is indistinguishable from every other atom with the same atomic number, weight and state. Stable atoms are near perfect examples of non-trivial machines that are immortal in the sense of never growing old and never wearing out. If one is desirous of creating an immortal thing out of ordinary matter, then it should be made up of stable atoms. When we combine atoms into molecules, then the energy needed to break apart such structures is very much less than that needed to break apart an atom. Thus, the environmental conditions required by immortal molecular structures is very much more constrained then that required by atoms. Subatomic particles are even more resistant to environmental conditions than are atoms. Neutrons can survive under conditions of great pressure where atoms cannot. However, a neutron cannot survive for long when it is isolated. The half life of an isolated neutron is about 15 minutes!
An example of an apparently immortal living thing is a one celled bacterium that divides as a means of reproduction. One could claim that a species is immortal since, despite the fact that every individual member of the species dies at the end of its lifetime, the species has no intrinsic limit on its lifetime. While it is easy to contemplate ordinary matter as components of an immortal being, there is a problem concerned with the motion of the parts of such a being. While a rock may be very much the same as it was 4 billion years ago, it is doubtful that a diesel engine will be the same after 4 billion years of operation. The reason is that local components, internal to the engine, have from time to time energies sufficient to break molecular bonds and thus to alter the system in ways that must be thought of as decay.
On the other hand, a computer may have no moving parts other than electrons or photons, and all operations may take place at energies so low as to allow for billions of years of operations with little chance of internally caused decay. Such a machine could have ways to minimize, compensate for and correct errors introduced by such external events as cosmic rays. It is possible and practical to build such a computer, powered by starlight, or by the decay of some Uranium U238 which has a half life of 4 billion years. Such a computer, launched into interstellar space, could have an expected lifetime of billions of years. It could be the host of a soul or of millions of souls, all of whom could then be said to be immortal.
There is one kind of mechanism that never has any necessary wear, decay or energy dissipation and that is an informational process. Just as the continual workings and motions of an atom are not dependent upon a continual supply of energy which must be dissipated, the workings of an informational process similarly are not necessarily dependant on a supply of energy which must be dissipated.
A properly designed computer, once put into operation, could continue to compute for billions of years, just as the solar system, once put into motion, could continue in motion for billions of years. In the case of a solar system, we know that there are various mechanisms slowly robbing it of energy, such as tidal effects or gravitational radiation. These effects can be so small as to allow a solar system to exist and function for many times the current age of the universe.
There is a methodology for designing computers, whose operation is very similar to modern computers, but where the necessary energy dissipation is reduced arbitrarily close to zero. This is much like the fact that we can build wires out of superconductors where the necessary energy dissipation due to the resistance of wires is reduced to zero. Such computers can be designed using Conservative Logic. There are two charming myths about reversible computers: first, that such computers, after finishing a computation, must be put into reverse to run the entire computation backwards to the beginning in order to not dissipate any energy and second, that such computers must run very slowly. These myths originate from a seminal paper by Charles Bennett where he showed that one could make a mechanical Turing Machine dissipate zero energy by such processes. He pointed out that his approach was sufficient but he never suggested that his approach was necessary! Andrew Ressler, gave an example of the detailed logic design of a dissipationless computer that was in every essential way very similar to ordinary computers, and it certainly did not have to run itself backwards from the end of the computation back to the beginning in order to not dissipate energy. On the contrary, one must be sure that the computer could, in principle, run backwards from the end of the computation back to the beginning as a form of proof that it is properly designed. There is, however, no necessity to run the whole computation backwards in order to have the system completely dissipationless.
If such a computer is effectively insulated from external energetic processes, it is not clear that there is any impediment to its continual operation based on the laws of physics; so long as its environment is reasonably benign. In addition, a complex computer system can have many mechanisms at work that allow for the correction of minor errors. Each such correction might best involve the dissipation of a very small amount of energy. In a well designed reversible computer, a few pounds of radioactive matter could provide all the power needed for billions of years of correcting whatever errors might occur. This means that errors introduced by, for example, an energetic cosmic ray, would not lead to a growth in erroneous computation, but rather the consequent errors would be detected and corrected without ever affecting the overall computational process other than by delaying things for a tiny amount of time.
Thus a soul could be essentially immortal. Since a soul is an informational construct, it has no parts to wear out or to get old. It is easy to see how a static soul can be immortal; it is written out on some permanent media, such as a future kind of CD-ROM and then stored in a safe place. A dynamic soul requires a host, but it can also exist as a static soul sequestered in some safe place. Just as one does a backup of a hard drive, so that after a catastrophic loss of a hard-drive one can buy and install a new hard drive and recover most of the data from the old hard-drive
For a soul to be immortal, it must either be resident in an immortal host, or it must be able to survive the mortality of each member of a sequence of hosts. Since the soul is an informational construct…. ….Of course, it all depends on the temperature….
To be continued and finished sometime soon… Ed Fredkin
