Mastodawn

jetstream Apr 28, 2023

Robert McNees Apr 27, 2023

A neat bit of physics history.

Lord Kelvin delivered the lecture "Nineteenth-Century Clouds over the Dynamical Theory of Heat and Light” to the Royal Institution of Great Britain #OTD in 1900. He spelled out two major problems that 19th century physics seemed unable to address.

Fixing these problems required radical new ideas, and eventually lead to the pillars of 20th century physics: special relativity and quantum mechanics.

You can read the lecture here: https://archive.org/details/londonedinburgh621901lond/page/n4/mode/2up

The London, Edinburgh and Dublin philosophical magazine and journal of science : Free Download, Borrow, and Streaming : Internet Archive

Title from cover

Internet Archive

jetstream Apr 27, 2023

Corey S Powell Apr 27, 2023

I did a double take when I read the title of the paper: "Ultrafast reversible self-assembly of living tangled matter"
Then I did another (a triple take?) when I saw the video. https://arxiv.org/abs/2210.03384
#Biology #LifeFindsAWay

Ultrafast reversible self-assembly of living tangled matter

Tangled active filaments are ubiquitous in nature, from chromosomal DNA and cilia carpets to root networks and worm blobs. How activity and elasticity facilitate collective topological transformations in living tangled matter is not well understood. Here, we report an experimental and theoretical study of California blackworms (Lumbriculus variegatus), which slowly form tangles over minutes but can untangle in milliseconds. Combining ultrasound imaging, theoretical analysis and simulations, we develop and validate a mechanistic model that explains how the kinematics of individual active filaments determines their emergent collective topological dynamics. The model reveals that resonantly alternating helical waves enable both tangle formation and ultrafast untangling. By identifying generic dynamical principles of topological self-transformations, our results can provide guidance for designing new classes of topologically tunable active materials.

arXiv.org

jetstream Apr 26, 2023

Ken White Apr 25, 2023

Kid2’s boyfriend — a very nice young man - recognized the computer game I was playing (a ludicrously overcomplicated strategy game called Europa Universalis IV) and we had a brief conversation about it and I could see her dying a little inside.

jetstream Apr 14, 2023

Girl on the Net Apr 13, 2023

Do you believe in love at first sight? My instinctive answer is always 'lol no', but then I remember my grandparents...

My Grandad met my Granny just before he had to head off for two years of military service. Time he hated, which he felt was thoroughly wasted.

There was an event on at the church the night before he got shipped off, and he went along. Ran into this beautiful, vivacious, funny woman who took his breath away. They spent all evening chatting, forgetting about everyone else. 🧵

jetstream Apr 1, 2023