Scientists solve the mystery of the arrow of time

arrow of time

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The passage of time from past to future is a central feature of our experience of the world. But precisely how this phenomenon, known as the arrow of time, arises from microscopic interactions between particles and cells is a mystery that researchers at the CUNY Graduate Center Initiative for the Theoretical Sciences (ITS) are helping to solve with the publication of a new article in the magazine Physical examination letters. The results could have important implications in various disciplines, including physics, neuroscience and biology.

Basically, the arrow of time stems from the second law of thermodynamics: the principle that the microscopic arrangements of physical systems tend to increase randomly from order to disorder. The more disordered a system becomes, the more difficult it is for it to find its way back to an ordered state, and the stronger the arrow of time. In short, the universe’s tendency toward disorder is the fundamental reason we experience time flowing in one direction.

“The two questions our team asked were: if we looked at a particular system, would we be able to quantify the strength of its arrow of time, and would we be able to determine how it emerges from the microscale, where cells and neurons interact, to the whole system?” said Christopher Lynn, first author of the paper and postdoctoral fellow in the ITS program. “Our findings are the first step to understanding how the arrow of time we experience in daily life emerges from these more microscopic details.”

To begin to answer these questions, the researchers explored how the arrow of time could be broken down by looking at specific parts of a system and the interactions between them. The parts, for example, could be the neurons that function in a retina. Looking at a single moment, they showed that the arrow of time can be broken down into different pieces: those produced by parts working individually, in pairs, in triplets, or in more complicated configurations.

Armed with this way of breaking down the arrow of time, the researchers analyzed existing experiments on the response of neurons in a salamander retina to different movies. In a movie, a single object moved randomly across the screen while another depicted all the intricacy of the scenes found in nature. In both films, the researchers found that the arrow of time emerged from simple interactions between pairs of neurons, not large, complicated groups. Surprisingly, the team also observed that the retina showed a stronger temporal arrow when observing random motion than a natural scene. Lynn said this latest finding raises questions about how our internal perception of the arrow of time aligns with the outside world.

“These findings may be of particular interest to neuroscience researchers,” Lynn said. “They could, for example, lead to answers about whether the arrow of time works differently in neuroatypical brains.”

“Chris’s decomposition of local irreversibility – also known as the arrow of time – is an elegant general framework that can provide a new perspective for exploring many high-dimensional non-equilibrium systems,” said Professor David Schwab. of Physics and Biology at the Graduate Center and the principal investigator of the study.


Characterizing the “arrow of time” in open quantum systems


More information:
Break down the local arrow of time into interacting systems, Physical examination letters (2022). journals.aps.org/prl/accepted/ … 6a8ee4316350b055c80c , On Arxiv: arxiv.org/abs/2112.14721v1

Provided by Graduate Center, CUNY

Quote: Scientists Unravel Mystery of the Arrow of Time (2022, August 22) Retrieved August 22, 2022 from https://phys.org/news/2022-08-scientists-unraveling-mystery-arrow.html

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