Society says time is money; but ANU physicist Peter Riggs says aspects of time might not even be real at all.

Article by: Elaine Obran, ANU Reporter

Time is largely a mystery.

It stretches and shrinks, slows down, then speeds up unexpectedly. Disappears at one place and then re-emerges at the next. The kettle won’t boil and the traffic won’t budge and yet it’s hard to recall what exactly happened in the past six months.

Over the past century, philosophers and physicists have debated the conundrum of time and whether its passage exists as part of the fabric of our reality or is merely a social construct that allows us to organise our daily lives.

Peter Riggs, a physicist and philosopher from the Research School of Physics at The Australian National University (ANU), is one of those people.

As one of Australia’s leading researchers on the nature of time, Riggs is familiar with both the science that can provide answers and the questions that remain.

“It may come as a surprise that the laws of physics do not contain any term corresponding to a passage of time. We only have a conscious [subjective] experience of time passing,” says Riggs.

He adds, “some philosophers have concluded that although time is real, the passage of time is an illusion. Most physicists also accept that there is no objective passage of time.”

In the absence of scientific evidence to quantify each passing moment, poets, artists, and writers offer their own meaning.

 As one of Australia’s leading researchers on the nature of time, Riggs is familiar with both the science that can provide answers and the questions that remain. Illustration: Crystal Li/ANU
Even Riggs finds artistic takes on time helpful.

“Do you know that Johnny Cash song called Folsom Prison Blues?”, he asks me in our interview, hitting pause on physics for a moment.

“ ‘I’m stuck in Folsom prison, and time keeps draggin’ on,’ that line sticks with me as a reference for how life can affect our perceptions of time.”

Outside of language, nature makes its own case. Seasons change. The sun makes its daily arc across the sky. Our circadian rhythms are in sync with the Earth’s orbit – or are they?

“It could appear that way,” Riggs admits.

“It could come down to the fact that the way our perceptions work is different from how we think they do.

“The apparent speed that time seems to pass arises from both our perception of the order of events and our perception of duration. This means that we do not have continuous awareness of how fast or slow time seems to pass; we are only aware in hindsight, even for events we have just witnessed.

“This experienced speed of the passage of time varies with emotional states, age, mood, and the activity being undertaken. Due to these factors, people witnessing the same events regularly judge the ‘speed’ to be different.”

The psychological pull of time can be so strong that on rare occasions it can seem to almost stand completely still.

“The phenomenon of time slowing down in the case of a life-altering event (such as a car accident) is something that has puzzled people for quite some time – excuse the pun,” Riggs says.

“It’s because when you’re in that event, your brain is recording everything in much more detail than normal, and the consequences of that create the illusion that you were perceiving time to slow down.”

But if our mind can shape the passage of time, where does that leave a ticking clock?

“Clocks don’t measure the passage of time. That’s a myth. They measure time intervals,” says Riggs.

“This leads most physicists to think that the passage of time is our consciousness being transferred from one moment to the next to the next, in a way that we don’t understand – which is hard getting your head around sometimes.”

As confusing as it is to understand, Riggs says our relationship with time is one we can’t live without.

“You simply can’t get away from it because there’s no physical existence without time. It’s an intrinsic part of the physical world. You couldn’t have life, and the universe simply couldn’t function without time.”

Like we said, time is largely a mystery.