Chris Aldrich | Chris Aldrich

🔖 Irreversibility and Heat Generation in the Computing Process by R. Landauer

Bookmarked Irreversibility and Heat Generation in the Computing Process (ieeexplore.ieee.org)

It is argued that computing machines inevitably involve devices which perform logical functions that do not have a single-valued inverse. This logical irreversibility is associated with physical irreversibility and requires a minimal heat generation, per machine cycle, typically of the order of kT for each irreversible function. This dissipation serves the purpose of standardizing signals and making them independent of their exact logical history. Two simple, but representative, models of bistable devices are subjected to a more detailed analysis of switching kinetics to yield the relationship between speed and energy dissipation, and to estimate the effects of errors induced by thermal fluctuations.

A classical paper in the history of entropy.

🔖 Why Boltzmann Brains Are Bad by Sean M. Carroll

Bookmarked Why Boltzmann Brains Are Bad (arxiv.org)

Some modern cosmological models predict the appearance of Boltzmann Brains: observers who randomly fluctuate out of a thermal bath rather than naturally evolving from a low-entropy Big Bang. A theory in which most observers are of the Boltzmann Brain type is generally thought to be unacceptable, although opinions differ. I argue that such theories are indeed unacceptable: the real problem is with fluctuations into observers who are locally identical to ordinary observers, and their existence cannot be swept under the rug by a choice of probability distributions over observers. The issue is not that the existence of such observers is ruled out by data, but that the theories that predict them are cognitively unstable: they cannot simultaneously be true and justifiably believed.

Covering Trump the Reuters Way | Reuters

Read Covering Trump the Reuters Way by Steve Adler (Reuters)

In a message to staff today, Reuters Editor-in-Chief Steve Adler wrote about covering President Trump the Reuters way.

🎧 The Personality Myth | Invisibilia (NPR)

Listened to The Personality Myth from Invisibilia | NPR.org

We like to think of our own personalities - and those of our spouses, children and friends - as predictable and constant over time. But what if they aren't? In this episode, Alix Spiegel visits a prison to explore whether there is such a thing as a stable personality. And Lulu Miller asks whether scientists can point to a single thing about a person that doesn't change over time. The answer might surprise you.

Not explicitly said, but this episode points out the heavy nurture side of the nature/nurture question in relation to the stability of one’s personality over time. In some sense, you are who those around you expect you to be. This also makes me think I ought to go back to working for a larger company with more people around me.

Yet another great episode, though to me not as intriguing as some of their other prior efforts. Still overall, a stellar podcast series.

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🔖 Energy flow and the organization of life | Complexity

Bookmarked Energy flow and the organization of life (Complexity, September 2007)

Understanding the emergence and robustness of life requires accounting for both chemical specificity and statistical generality. We argue that the reverse of a common observation—that life requires a source of free energy to persist—provides an appropriate principle to understand the emergence, organization, and persistence of life on earth. Life, and in particular core biochemistry, has many properties of a relaxation channel that was driven into existence by free energy stresses from the earth's geochemistry. Like lightning or convective storms, the carbon, nitrogen, and phosphorus fluxes through core anabolic pathways make sense as the order parameters in a phase transition from an abiotic to a living state of the geosphere. Interpreting core pathways as order parameters would both explain their stability over billions of years, and perhaps predict the uniqueness of specific optimal chemical pathways.

Download .pdf copy

[1]

H. Morowitz and E. Smith, “Energy flow and the organization of life,” Complexity, vol. 13, no. 1. Wiley-Blackwell, pp. 51–59, 2007 [Online]. Available: http://dx.doi.org/10.1002/cplx.20191