It isn't possible to pinpoint exactly who is most responsible for humankind's best invention of all time. I am, of course, talking about science—the process that lets us test our assumptions, gather evidence and analyze the results. That process has propelled advances in basic research and practical applications for everything from extending our lives to expanding our physical and mental horizons.

Around the third century b.c. Aristotle and other ancient Greek philosophers put us on the right track, employing measurement to help learn about the world. Muslim scholars later pioneered the basics of testing and observation, the foundations of the scientific method, perhaps more than 1,000 years ago. Among the others who helped to refine the process were Roger Bacon, who fostered the use of inductive reasoning in the 1200s; Galileo, who put Bacon's ideas into practice in the late 1500s and early 1600s; and René Descartes, Francis Bacon and Isaac Newton, who built on the method shortly before and during the Enlightenment of the 1700s—to name a mere handful.

In our single-topic issue, “Beyond the Limits of Science,” we celebrate just how far we have come as a species using that rational system. A series of apparent barriers now stands before us in our current life span: the physical body's performance, individual intellectual capacity, engineering capabilities and even collective knowledge. How will we move past them? In this special edition, we promise a mind-expanding armchair journey, with leading scientists and expert journalists as guides, to the edges—and beyond—of what is and will be possible.

For instance, in “Can We Keep Getting Smarter?” journalist Tim Folger writes about the Flynn effect, a kind of Moore's law for measures of intelligence. In a world that prizes logic and abstraction, a positive feedback loop has led to our continuous progress in mental adaptation and the invention of new technologies. “How We All Will Live to Be 100,” by staff editor Katherine Harmon, examines efforts to lead longer, healthier lives by attacking our ancient enemies of illness and decrepitude. Casting aside the idea of mortality altogether, contributing editor Davide Castelvecchi describes “Questions for the Next Million Years”—research we could do if an individual's career or life span were no obstacle.

As Newton famously put it: “If I have seen further, it is by standing on the shoulders of giants.” Following his model, we can use the process of science to exceed today's boundaries. Perhaps our only true limit is the human imagination itself.