In 1908 John McTaggart wrote The Unreality of Time, and using his A and B series of time he argued that our perception of time is an illusion. Of the A series, he argues this:
"If time exists it must be explained by the A series, which is how we normally think about time. This is a tensed series, as in past, present, and future. A cup of coffee was hot in the past, is lukewarm in the present, and cold in the future. The United States was created in the past, exists in the present, and will no longer exist in the future. In this series are three distinct instances."
McTaggart juxtaposes a B series against the A series. This series is relational, or durational. One way to think of it is as events before the now and after the now. A cup of coffee had hot temperature, is colder temperature in the present, and colder after the present. Put in another way to think about it, the United States was founded in the past, exists after its founding, and will no longer exist after its founding. From both perspectives the instances are not distinct, but relational, enduring from one into another. The B series can be likened to space. The wall is there, and a window elsewhere. They are spatially related. The B series as relational is not inherently separate (distinct) from other time-moments, just as space has no difference in it. As the wall is there, the window elsewhere, so events in the B series can be located as before and after.
Many rich and profound complications arise from thinking about the two series but the central point is that they are contradictory. One is tensed, the other tenseless. The A series depends on personal experience and perspective. "I am drinking hot coffee today." The B series does not. The experience and perspective are not there. "I recall drinking hot coffee today."
Because they are contradictory, McTaggart says time is not real. His legacy is that he left A theorists and B theorists debating which kind of time is true, continuing a discussion traced back to Parmenides (reality is timeless, unchanging) and Heraclitus ("You can't step into the same river twice").
So what is time? If nobody asks, I know. If they ask and I try to explain, I do not know. (St Augustine, Bishop of Hippo, 354-430.)
In his book, The End of Time: The Next Revolution in Physics, Julian "Barbour asserts that time simply doesn't exist." Barbour starts with the notion that time is just a way of describing change. He means that to measure time you have to have something that moves. How long does it take to get from point A to Point B?
~ "There's only change, not time. Things move around; time may just be a way of noting that. But Barbour goes further. He says there's no such thing as motion either. Instead, Barbour sees a universe filled with static instants -- instants that contain 'records' that fool any conscious beings who happen to find themselves encased in one into believing that things have moved and time has passed."
~"This common-sense view was one of many forever altered by Einstein's theories. We see time this way, he made clear, only because we move so slowly. If you could peddle your bicycle at something almost in the neighborhood of the speed of light, relative to an observer, your watch and your aging process would appear -- to that observer -- to slow. (From your own perspective, time, unfortunately, would still keep chugging along at its usual dispiriting pace, which makes it unlikely that anyone will figure out how to turn this phenomenon into a wrinkle cream.)"
~"Relativity found time a home as one of the four dimensions in something called spacetime. But it hardly settled the question of what time is. And the idea that time slows down in certain circumstances made it easier to imagine that time was just a construct of us observers, not itself a fact of nature."
~"What if, Barbour wonders, we just imagine a kingfisher to be flying? After all, it isn't exactly the same bird at perch A and perch B: Its molecules constantly change; its atoms constantly change. What if our brain has captured a few snapshots of kingfisher-in-flight that it plays -- movie-like -- in such a way that we think we see continuous motion?"
~"What if the instants we inhabit somehow happen to be filled with 'records' -- images of kingfishers with their wings spread, tread marks, 'memories,' fossils -- that manage to delude us into thinking that birds fly, cars lurch, species become extinct; 'records' that manage to delude us into thinking that we are scurrying along some sort of path from the past to the future? Isn't it true that all we know now about the past or the future comes from thoughts or objects we experience now -- in the present?"
~"What if, Barbour then asks, we're always trapped in one moment or another and everything else -- your sense, for example that X number of minutes ago you moved your hand and clicked on FEED -- is a kind of illusion, somehow evoked by the structure of this particular, all-encompassing moment? What if, in other words, our whole sense that things move is an illusion, as -- in another context -- our sense that the earth does not move proved to be an illusion."
~"This is, if it helps any, quite similar to the view of time presented in Kurt Vonnegut's 1969 novel Slaughterhouse Five, which Barbour has not yet read. ('I know,' he says. 'People keep telling me I should look at it.') Vonnegut describes most earthlings as trapped in moments like 'bugs in amber.' Billy Pilgrim, the book's main character, however, repeatedly comes 'unstuck in time': He jumps, in no particular order (though in accordance with the needs of Vonnegut's narrative), from one point in his life to another. Moreover, on the planet Tralfamadore, which Pilgrim visits, 'all time' is visible at once, as we 'might see a stretch of the Rocky Mountains. It does not change. It simply is.' That Rocky Mountain-like view of all time is remarkably similar to Barbour's Platonia."
The above comments are excerpts from a review of his book published in the now defunct Feed Magazine on July 14, 2000 by Mitchell Stephens. I wanted to link you to the review but the link is dead. More of the review is below. Or click her for a Nature article on why time is an illusion according to classical physics.
