Virtualization and virtual machines have been getting a lot of attention lately. This is mainly due to the increased availability and reliability of commercial virtual machine software from VMware and Microsoft. There is nothing new under the sun, though. Gerald J. Popek and Robert P. Goldberg's seminal 1974 paper, "Formal Requirements for Virtualizable Third Generation Architecture," pretty much defined the playing field for virtual machines, even though the field they were playing on was big iron. We may be heading down the road of esoterica today–my spell checker doesn't even recognize the word virtualizable.

So, What Is Reality?

Just what do we mean when we use the term virtual? It generally is applied to something that is not conceived of or perceived as real but yet acts like a real thing. Then what is reality? Ren? Descartes' greatest contribution to Western culture was his work in mathematics, but he still is best known for his contention that his reality was defined by his ability to think or reason–cogito ergo sum. His ideas provided the basis of Western rational philosophy, which in turn was opposed by empiricism. The Irish philosopher Bishop George Berkeley took the idea to its extreme by asserting the only real existence of anything is the perception we have of that thing in our mind. Thus, nothing is real beyond its perception–and you know what that means for trees falling in the forest. Dr. Samuel Johnson, the 18th century poet, essayist, and biographer, was particularly frustrated with Bishop Berkeley's theories and is reputed to have kicked a heavy stone, saying, "Thus, I refute him."