According to Wikipedia, the arrow of time is a term coined by British astronomer Arthur Eddington to distinguish between two types of physical processes:
Physical processes at the microscopic level are believed to be either entirely or mostly time symmetric, meaning that the theoretical statements that describe them remain true if the direction of time is reversed; yet when we describe things at the macroscopic level it often appears that this is not the case: there is an obvious direction (or flow) of time. An arrow of time is anything that exhibits such time-asymmetry.
Put another way:
Any process that happens regularly in the forward direction of time but rarely or never in the opposite direction, such as entropy increasing in an isolated system, defines what physicists call an arrow of time in nature.
There are also some helpful rules about the arrow of time:
1) It is vividly recognized by consciousness.
2) It is equally insisted on by our reasoning faculty, which tells us that a reversal of the arrow would render the external world nonsensical.
3) It makes no appearance in physical science except in the study of organization of a number of individuals.
More on the arrow of time, including a great interview with Caltech theoretical physicist Sean Carroll, here at The Long Now Blog.
“You’re in a chair, in the sky!” I needed a laugh today and found one thanks to this great clip of Louis CK from Conan O’Brian via Kevin Kelly. (Also: a little free wisdom from Conan here via 37signals—I thought the same thing when I read this article in NYT.)
It’s 2050, and you have amassed a library of some three million PDF documents. Ten years earlier, amid bad management and shareholder uproar, Adobe was forced out of business, and a new format has emerged as the portable document standard. With support for PDFs dwindling each year, where do you turn to access your information? The Format Exchange, built by the visionary Long Now Foundation, is “a central repository and discussion space for file format conversion to aid in knowledge transfer. The goal is to build a community and tool to help allow the information we are all now creating digitally to move into the future.” Brilliant. Update: Scott wrote in to share a few more thoughts on this: “You may want to check out Library of Congress MARC/XML and PDF/A formats. They are great archival digital formats that forward thinking people are working hard at. But note that even though the formats may be accessible, big businesses don’t often implement the standards. […] The latest Wired magazine also displays the exponential decline of our data storages life expectancy. Stone tablets have been found up to 7,000 years old and the CDs we burn last about 5 years.”
“FOR IMMEDIATE RELEASE … SEPTEMBER 22, 2019 … Humans have 23 years to go … Global Extinction Awareness System starts the countdown for Homo sapiens. PALO ALTO, CA: Based on the results of a year-long supercomputer simulation, the Global Extinction Awareness System (GEAS) has reset the ‘survival horizon’ for Homo sapiens—the human race—from ‘indefinite’ to 23 years.” So begins The Institute for the Future’s game Superstruct, with a press release 11 years in the future.
Clarke’s Three Laws from “Profiles of the Future” (1962): “1) When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong. 2) The only way of discovering the limits of the possible is to venture a little way past them into the impossible. 3) Any sufficiently advanced technology is indistinguishable from magic.” Arthur C. Clarke passed away this Wednesday. He will be missed.
“In 2002, [Desert Space Foundation Director Josh] Abbey created a design competition to find a permanent warning sign for the proposed nuclear waste site [in Yucca Mountain, Nevada]. The purpose of the competition, he says, is to find a universal warning sign which conveys that the deposit is highly dangerous. One caveat: the symbols have to work even if language or communication breaks down in the future. And the design has to last at least 10,000 years.” Wow. That’s quite a challenge. Read on in this thoughtful NPR piece on Yucca Mountain.