By Zeeya Merali
George Ellis is not afraid to rock the establishment. In his youth in South Africa, his target was a recognizably corrupt and racist government. Now a cosmologist at the University of Cape Town, Ellis has set his sights on something more abstract: the flow of time itself.
First developed by Albert Einstein early in the 20th century, the orthodox view holds that the passage of time is an illusion. There is no difference between the past and the future — both are set in stone. Yet for Ellis, the philosophical implications of this mainstream theory do not simply run counter to our intuitions; he considers them dangerous because they rob us of free will and moral accountability. Ellis’ scientific goal, motivated by his ethical views, is to put time back into physics, allowing the cosmos to create its fate and giving us the ability to change our destiny.
Origin of a Cosmologist
Ellis refined his new theory of reality, in which time exists and the future remains unwritten, while on sabbatical at the University of Cambridge, the institution that during the 17th century boasted Isaac Newton, first as a student and later a professor.
In Newton’s Principia Mathematica, the British physicist formulated a notion of time that fits with our everyday experiences. He pictured a universal stopwatch whose ticks beat out the steady passage of seconds, minutes and hours across the cosmos. No matter where you are or how you are moving, in Newton’s view, you would agree that Ellis takes exactly 10 minutes to sip his coffee on a bench in a leafy quadrangle of Trinity College before placing his cup down beside him. Every 15 minutes, he hears the bell of Trinity’s ornate clock tower — set in place half a century before the young Newton ever set foot on college grounds — punctuating the forward march of time.
Ellis’ own march began in Johannesburg in 1939, when he was born to an English immigrant father. The family moved to Cape Town after Ellis turned 12, and he was placed in a boarding school. There he became fascinated with tinkering with model trains, breaking them apart and then putting them back together to learn how they worked.
But what might have been idyllic formative years were tainted by the 1948 institutionalization of apartheid, a set of laws that enforced white supremacist rule over those categorized as “blacks,” “coloreds” and “Asians.” As a white South African, Ellis admits, “it would have been easy to be totally isolated from this,” were it not for his parents. Both were vocal opponents to the regime, using the newspaper his father edited to criticize the government’s racism.
As an undergraduate, Ellis studied architecture for a year and then switched to physics and math. He laughs that while he “did not have the imagination to come up with designs for buildings,” he was attracted to discovering the blueprints of the larger universe. Like all physics students in the 1960s, he learned that these blueprints mostly had been laid out by Einstein. That’s when time started getting complicated for Ellis.
On The Block
In 1905, Einstein overturned Newton’s harmonious picture of a standard universal time. He replaced it with a discordant, relative view in which different people could disagree about the duration of events, and even the order in which they happened. The young Einstein came to the remarkable realization that time was, in fact, a fourth dimension, alongside the three dimensions of space that we see around us, creating what has become known as the “block universe” picture of reality.
To explain what a block universe looks like, imagine taking successive photographs of a location, says Ellis, such as a series of snapshots of anxious Cambridge students hurrying across the Trinity quadrangle, books in hands, on their way to exams. If you projected the photos one after another, you would make a movie through which time appeared to pass, corresponding to our intuitive view of time’s flow. But if you stack the images on top of each other, you would see the students’ entire journeys across the quadrangle mapped out in front of you, all at once. The second example is similar to the block universe view, where past, present and future all coexist simultaneously, and the passage of time has no meaning; all events coexist side by side.
Of course, a set of photographs captures only two dimensions of space mapped out along the time dimension. Extend this to three spatial dimensions and across the whole cosmos, encompassing both its entire history and all future events yet to come, and you have Einstein’s four-dimensional block universe — a static record that spans all that ever has happened, and all that ever will happen.
What’s most disarming about the block universe, remarks Ellis, is that unlike a movie that plays through a series of successive instants, there is no special point in time that all inhabitants would agree on as “now” — no unique marker that separates the fixed past from the open future. Just as two students seated in different corners of the quadrangle may disagree over the length of the shadow cast by the Trinity College clock tower, based on their perspective, so might it be with time: Einstein realized that since time is just another dimension in the block universe, then depending on where two people are in space-time, they could also disagree on the duration of events. Some would, completely accurately, argue that it took Ellis longer than 10 minutes to drink his coffee.
There’s more. Just as the students would disagree on whether the clock tower was to Ellis’ right or left, depending on where they stood, two people in Einstein’s block universe could even argue over the order in which events occurred. To one person, the Trinity clock might strike 2 p.m. before Ellis finished his last sip, and to another, the bell chimed only after he was done. These discrepancies are based purely on the speed and direction the people are traveling in the block universe, because this affects the time it takes light from those events to reach them. These time differences are imperceptible at human speeds, but they have been verified in experiments involving the International Space Station as well as extra-fast airplanes.
In the block universe, then, what someone perceives as the future is what someone else saw as the past, depending on the person’s position and motion. Events that have yet to happen for one person, it appears, have already happened for another. The future, though it remains unknown to you, seems to be written already. Einstein himself described it thus: “People like us, who believe in physics, know that the distinction between past, present and future is only a stubbornly persistent illusion.”
Most physicists have learned to accept that the direction of time chosen as “forward” is arbitrary in Einstein’s conception of the universe and the fundamental equations governing our cosmos, but Ellis’ gut told him to look deeper. “This is where I come back to trying to have a realistic feel for things,” he says.
Part 2 to follow
