“People like us, who believe in physics, know that the distinction between past, present, and future is only a stubbornly persistent illusion.”
~ Albert Einstein
From a human perspective, physics has a problem with time. We have no difficulty defining a special moment called “now” that is distinct from the past and the future, but our theories cannot capture the essence of the moment. The laws of nature deal only with what happens between certain time intervals.
David Mermin of Cornell University claims to have solved this problem using a principle similar to the one he and others have applied to quantum theory (see main story). We should simply abandon the notion that an objectively determinable space-time exists.
Instead of forming a series of slices or layers that from some viewpoint correspond to a “now” or “then”, Mermin’s space-time is a mesh of intersecting filaments relating to the experiences of different people (arxiv.org/abs/1312.7825). “Why promote space-time from a 4D diagram, which is a useful conceptual device, to a real essence?” he asks. “By identifying my abstract system with an objective reality, I fool myself into regarding it as the arena in which I live my life.”
Things such as an interval of time or the dimensionality of space, after all, are not stamped on nature for us to read off; a newborn baby has no conception of them. They are merely useful abstractions we develop to account for what clocks and rulers do. Some of these high-level abstractions we construct for ourselves as we grow up, others were constructed by geniuses and have been passed on to us in school or in books, says Mermin. “And some of them, like quantum states, most of us never learn at all.”
Matthew Chalmers is a freelance writer based in Bristol, UK, From issue 2968 of New Scientist magazine, page 32-35.
Below is a clip of Brian Greene, Professor of Physics and Mathematics at Columbia University, presents interesting information about the nature of space-time, including an explanation of how past, present, and future all exist in the now.
A brief video with David Eagleman who explains how the human brain understands time, and why it may not always be as it seems.
