Mind uploading, also known as whole brain emulation, mind transfer, or simply "uploading" (never "downloading") is the hypothetical act of simulating someone's brain in a computer so well that the simulation possesses all the same intelligence, memories, personality, identity, and consciousness of the original person. If successful, this could allow human beings to live for an extremely long time, as it would be much easier to heal health problems and the effects of aging if it required little more than changing a few lines of code. The ethical implications of mind uploading have been explored at some length in science fiction and in certain branches of philosophy.
Some people strongly object to the notion that mind uploading is even possible, as the qualities of human intelligence are often considered inseparable from their biological substrate. However, the concept of uploading is entirely compatible with causal functionalist philosophies of mind, popular among brain scientists, which assert that the brain is only defined by the causal interactions and functions of its components, rather than the material of which they are made. The popular opinion towards the concept of mind uploading is difficult to gauge, as few people have even heard of the concept, much less given it serious thought.
Mind uploading is beyond the capabilities of our present-day technology, but not by as much as many people think. Portions of a mouse brain have been simulated at very high resolution inside computers. The required equipment for a successful mind upload session would include:
1) High-resolution scanners, such as an electron microscope or nanomachines.
2) A computer with large amounts of memory storage and processing power, for storing the data as it comes in and implementing it as a program once the scanning is completed.
3) A virtual environment for the upload to live within once the uploading process is complete. This might resemble a much more advanced version of an MMORPG (massively multiplayer online role-playing game), such as SecondLife or World of Warcraft.
In destructive uploading, the subject's brain would be frozen in liquid nitrogen, then sliced into small segments, which would be scanned. The scan would then be built into a running program which would be implemented on an advanced computer. Estimates for the necessary processing power of such a computer range between about 1013 (10 trillion) to 1017 (100,000 trillion) operations per second. For comparison, the fastest computer in 2007, Blue Gene/L, operates at about 500 trillion operations per second.
Alternatives to destructive uploading include non-destructive uploading, where neurons are scanned using blood-borne nanomachines rather than destructive slicing, or cyborgization, where parts of the brain are progressively replaced with cybernetic components until the entire thing becomes a computer.
For now, mind uploading remains in science fiction, but it's only a matter of time until the technology becomes available, and people start attempting the procedure outlined above.