Cryonics:
The preservation of the human brain after death—with a view to subsequent revival—involves the freezing process and long-term storage. Both must protect against structural degradation caused by ice formation, residual molecular motion, and background radiation—any of which could compromise the recipient's identity.
Exists today, albeit using relatively new technology.
If freezing techniques could be perfected and storage conditions improved—approaching absolute zero and shielding against radiation—then indefinite preservation may become viable.
What's possible?
Artificial Intelligence:
Systems capable of general intelligence—able to learn and adapt across any task—are widely considered achievable, perhaps even inevitable. However, intelligence does not imply self-awareness or the capacity for emotion. A system may learn, reason, and even appear creative, without any underlying subjective experience.
Exists today, and progress is rapid.
The next step—creating systems with genuine sapience and sentience—is far more uncertain. Increasing computational power may be necessary for such systems, but is not known whether this is sufficient.
Revival of a preserved brain:
This process requires repairing any damage caused during preservation, reactivating metabolic processes, and re-establishing circulation and neural activity. Crucially, this must be achieved without modifying the fine structure of the brain, as even small changes may irreversibly affect memory, personality, and continuity of identity.
Not currently achievable in any meaningful form.
While none of these challenges are fundamentally prohibited by the laws of physics, they require a level of precision far beyond current medical capability.
Cloning is the creation of a genetically identical copy of a living organism. It reproduces biology, not the mind.
Already performed in animals, including primates, demonstrating that the process is viable.
In principle, extending this to humans is not a question of possibility, but of refinement—improving success rates, reducing abnormalities, and ensuring safe development to term.
Human cloning:
The surgical removal of a human brain and its implantation into another body, with the aim of restoring full function and preserving identity. This would require the precise integration of millions of neural connections within the spinal cord and peripheral nervous system.
Not currently achievable in any meaningful form.
While none of these challenges are fundamentally prohibited by the laws of physics, they demand a level of precision far beyond current medical capability. Achieving this would likely require entirely new approaches such as nanotechnology or guided biological repair.
Brain transplantation:
The ability of machines to independently replicate themselves from available raw materials—often referred to as von Neumann probes—requires advanced robotics, resource extraction, and manufacturing capabilities.
Not currently achievable in any meaningful form due to the complexity of fully autonomous manufacturing.
None of the underlying challenges are inherently impossible, but with sufficient energy, raw materials, and control systems, such processes could scale exponentially—eventually transforming entire environments.
Machine self-replication:
The controlled confinement of plasma at extremely high temperatures to enable continuous nuclear fusion, producing vast amounts of energy from minimal fuel.
Fusion reactions have been achieved experimentally, but stable containment and sustained, net-positive output remain unresolved.
None of the underlying challenges are prohibited by the laws of physics, but they require precise control of extreme conditions and highly advanced materials. If achieved, fusion would provide a near-limitless, scalable energy source.
Fusion containment: