Time

Arrows of Time

A project by Quanta Magazine. Text by Dan Falk. Design and illustrations by Eleanor Lutz and Olena Shmahalo.

The human mind has long grappled with the elusive nature of time: what it is, how to record it, how it regulates life, and whether it exists as a fundamental building block of the universe. This timeline traces our evolving understanding of time through a history of observations in CULTURE, PHYSICS, TIMEKEEPING & BIOLOGY.
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COSMOLOGY(2016)   A Debate Over the Physics of Time By DAN FALK Our best theories suggest that the universe is fixed and time only appears to pass. Yet some physicists hope to replace this “block universe” with a physical theory of time. Read the article ******************************* UNIVERSALITY(2019)   The Universal Law That Aims Time’s Arrow By NATALIE WOLCHOVER A new look at a ubiquitous phenomenon has uncovered unexpected fractal behavior that could give us clues about the early universe and the arrow of time. Read the article

Time: History

A revolution in time

Once local and irregular, time-keeping became universal and linear in 311 BCE. History would never be the same again

Paul J Kosmin

is John L Loeb associate professor of the humanities, specialising in the history of the Ancient Greek world, at Harvard University in Massachusetts. His most recent book is Time and Its Adversaries in the Seleucid Empire (2018).

2,900 words

Edited by Sam Dresser

What year is it? It’s 2019, obviously. An easy question. Last year was 2018. Next year will be 2020. We are confident that a century ago it was 1919, and in 1,000 years it will be 3019, if there is anyone left to name it. All of us are fluent with these years; we, and most of the world, use them without thinking. They are ubiquitous. As a child I used to line up my pennies by year of minting, and now I carefully note dates of publication in my scholarly articles. 

Now, imagine inhabiting a world without such a numbered timeline for ordering current events, memories and future hopes. For from earliest recorded history right up to the years after Alexander the Great’s conquests in the late 4th century BCE, historical time – the public and annual marking of the passage of years – could be measured only in three ways: by unique events, by annual offices, or by royal lifecycles./

Time

(Illustration by Stephan Schmitz)

The illusion of time There is no such thing as time, says theoretical physicist Carlo Rovelli — reality is just a complex network of events onto which we project sequences of past, present and future. Cosmologist Andrew Jaffe enjoys the exploration of modern physics’ big ideas in Rovelli’s compact and elegant new book — but he doesn’t buy into all of Rovelli’s conclusions. Nature | 4 min read