Scientists are unraveling the mystery of the arrow of time

There is a flow of time from the past to the future. The CUNY Graduate Center Initiative for the Theoretical Sciences is helping to uncover the mystery of how the arrow of time arises by publishing a new paper in the journal Physical Review Letters. Implications in a variety of disciplines are possible from the findings.

The arrow of time can be traced back to the second law of thermodynamics, which states that random arrangements of physical systems tend to move from order to order. The stronger the arrow of time, the harder it is for a system to return to an ordered state. Time flowing in one direction is due to the universe's tendency towards disorder.

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 sort out how it emerges from the micro scale? The first step in understanding the arrow of time that we experience in daily life is provided by our findings.

To answer these questions, the researchers looked at how the arrow of time could be broken down by observing certain parts of a system. It's possible that the parts are the cells that function in the eye. Looking at a single moment, they showed that the arrow of time can be broken down into different pieces.

The researchers used this method of decomposing the arrow of time to analyze existing experiments on the response of salamanders to different movies. One movie showed a single object moving across the screen while another showed the full complexity of the scene. The arrow of time came from the simple interactions between pairs of neurons. The team found that the retina showed a stronger arrow of time when watching random motion. Lynn raised questions about how our internal perception of the arrow of time becomes aligned with the outside world.

Lynn said that the results may be of interest to neuroscience researchers. They could lead to questions about the function of the arrow of time in brains that are atypical.

"Chris' decomposition of local irreversibility, also known as the arrow of time, is an elegant, general framework that may provide a novel perspective for exploring many high-dimensional, nonequilibrium systems."

More information: Decomposing the local arrow of time in interacting systems, Physical Review Letters (2022). journals.aps.org/prl/accepted/ … 6a8ee4316350b055c80c , On Arxiv: arxiv.org/abs/2112.14721v1 Journal information: Physical Review Letters , arXiv