org:inst   36

Stability of the Solar System - Wikipedia
The stability of the Solar System is a subject of much inquiry in astronomy. Though the planets have been stable when historically observed, and will be in the short term, their weak gravitational effects on one another can add up in unpredictable ways. For this reason (among others) the Solar System is chaotic,[1] and even the most precise long-term models for the orbital motion of the Solar System are not valid over more than a few tens of millions of years.[2]

The Solar System is stable in human terms, and far beyond, given that it is unlikely any of the planets will collide with each other or be ejected from the system in the next few billion years,[3] and the Earth's orbit will be relatively stable.[4]

Since Newton's law of gravitation (1687), mathematicians and astronomers (such as Laplace, Lagrange, Gauss, Poincaré, Kolmogorov, Vladimir Arnold and Jürgen Moser) have searched for evidence for the stability of the planetary motions, and this quest led to many mathematical developments, and several successive 'proofs' of stability of the Solar System.[5]


The planets' orbits are chaotic over longer timescales, such that the whole Solar System possesses a Lyapunov time in the range of 2–230 million years.[3] In all cases this means that the position of a planet along its orbit ultimately becomes impossible to predict with any certainty (so, for example, the timing of winter and summer become uncertain), but in some cases the orbits themselves may change dramatically. Such chaos manifests most strongly as changes in eccentricity, with some planets' orbits becoming significantly more—or less—elliptical.[7]

Is the Solar System Stable?:

Is the Solar System Stable?:
nibble  wiki  reference  article  physics  mechanics  space  gravity  flux-stasis  uncertainty  robust  perturbation  math  dynamical  math.DS  volo-avolo  multi  org:edu  org:inst  papers  preprint  time  data  org:mat 
november 2017 by nhaliday
Controversial New Theory Suggests Life Wasn't a Fluke of Biology—It Was Physics | WIRED
First Support for a Physics Theory of Life:
Take chemistry, add energy, get life. The first tests of Jeremy England’s provocative origin-of-life hypothesis are in, and they appear to show how order can arise from nothing.
news  org:mag  profile  popsci  bio  xenobio  deep-materialism  roots  eden  physics  interdisciplinary  applications  ideas  thermo  complex-systems  cybernetics  entropy-like  order-disorder  arrows  phys-energy  emergent  empirical  org:sci  org:inst  nibble  chemistry  fixed-point  wild-ideas 
august 2017 by nhaliday
Extended spider cognition | SpringerLink
Spiders do not seem to be cognitively limited, displaying a large diversity of learning processes, from habituation to contextual learning, including a sense of numerosity. To tease apart the central from the extended cognition, we apply the mutual manipulability criterion, testing the existence of reciprocal causal links between the putative elements of the system. We conclude that the web threads and configurations are integral parts of the cognitive systems. The extension of cognition to the web helps to explain some puzzling features of spider behaviour and seems to promote evolvability within the group, enhancing innovation through cognitive connectivity to variable habitat features. Graded changes in relative brain size could also be explained by outsourcing information processing to environmental features. More generally, niche-constructed structures emerge as prime candidates for extending animal cognition, generating the selective pressures that help to shape the evolving cognitive system.
study  cocktail  bio  nature  neuro  eden  evolution  intelligence  exocortex  retrofit  deep-materialism  quantitative-qualitative  multi  org:mag  org:sci  popsci  summary  nibble  org:inst 
april 2017 by nhaliday
Evolution Runs Faster on Short Timescales | Quanta Magazine
But if more splashes of paint appear on a wall, they will gradually conceal some of the original color beneath new layers. Similarly, evolution and natural selection write over the initial mutations that appear over short timescales. Over millions of years, an A in the DNA may become a T, but in the intervening time it may be a C or a G for a while. Ho believes that this mutational saturation is a major cause of what he calls the time-dependent rate phenomenon.

“Think of it like the stock market,” he said. Look at the hourly or daily fluctuations of Standard & Poor’s 500 index, and it will appear wildly unstable, swinging this way and that. Zoom out, however, and the market appears much more stable as the daily shifts start to average out. In the same way, the forces of natural selection weed out the less advantageous and more deleterious mutations over time.
news  org:mag  org:sci  evolution  bio  nature  mutation  selection  time  methodology  stylized-facts  genetics  population-genetics  genomics  speed  pigeonhole-markov  bits  nibble  org:inst 
march 2017 by nhaliday
How Humans Evolved Supersize Brains | Quanta Magazine
Based on her studies, Herculano-Houzel has concluded that primates evolved a way to pack far more neurons into the cerebral cortex than other mammals did. The great apes are tiny compared to elephants and whales, yet their cortices are far denser: Orangutans and gorillas have 9 billion cortical neurons, and chimps have 6 billion. Of all the great apes, we have the largest brains, so we come out on top with our 16 billion neurons in the cortex. In fact, humans appear to have the most cortical neurons of any species on Earth. “That’s the clearest difference between human and nonhuman brains,” Herculano-Houzel says. It’s all about the architecture, not just size.
news  org:mag  org:sci  popsci  evolution  sapiens  neuro  eden  density  comparison  nature  data  scale  nibble  org:inst 
march 2017 by nhaliday
A Unified Theory of Randomness | Quanta Magazine
Beyond the one-dimensional random walk, there are many other kinds of random shapes. There are varieties of random paths, random two-dimensional surfaces, random growth models that approximate, for example, the way a lichen spreads on a rock. All of these shapes emerge naturally in the physical world, yet until recently they’ve existed beyond the boundaries of rigorous mathematical thought. Given a large collection of random paths or random two-dimensional shapes, mathematicians would have been at a loss to say much about what these random objects shared in common.

Yet in work over the past few years, Sheffield and his frequent collaborator, Jason Miller, a professor at the University of Cambridge, have shown that these random shapes can be categorized into various classes, that these classes have distinct properties of their own, and that some kinds of random objects have surprisingly clear connections with other kinds of random objects. Their work forms the beginning of a unified theory of geometric randomness.
news  org:mag  org:sci  math  research  probability  profile  structure  geometry  random  popsci  nibble  emergent  org:inst 
february 2017 by nhaliday

related tags

aaronson  abstraction  academia  accretion  acm  acmtariat  adversarial  ai  algorithms  amt  analysis  announcement  applications  approximation  arrows  article  asia  automation  bandits  ben-recht  berkeley  biases  big-picture  big-surf  bio  biotech  bits  blog  career  cartoons  chemistry  cocktail  comparison  complex-systems  complexity  computation  concept  conceptual-vocab  constraint-satisfaction  convexity-curvature  cooperate-defect  course  crispr  critique  cs  culture  current-events  curvature  cybernetics  data-science  data  database  debate  deep-learning  deep-materialism  deepgoog  definition  density  differential  discrete  distribution  dynamical  eden  egt  embodied  emergent  empirical  entropy-like  essay  estimate  ethical-algorithms  events  evolution  exocortex  expanders  expert-experience  expert  exposition  feynman  fixed-point  flux-stasis  formal-methods  games  genetics  genomics  geoengineering  geography  geometry  giants  government  gowers  gradient-descent  graph-theory  graphs  gravity  ground-up  hardness  higher-ed  hmm  ideas  impact  intelligence  interdisciplinary  intersection-connectedness  intersection  interview  iteration-recursion  iterative-methods  kernels  korea  lattice  law  learning-theory  lecture-notes  lectures  lens  liner-notes  list  logic  lower-bounds  machine-learning  maps  markov  math.ds  math.nt  math  measure  mechanics  metabuch  methodology  michael-nielsen  moments  mrtz  multi  mutation  nature  neuro  news  nibble  online-learning  open-problems  optimization  order-disorder  org:bleg  org:edu  org:mag  org:mat  org:nat  org:sci  organization  overflow  p:**  p:whenever  papers  parasites-microbiome  pdf  people  perturbation  phys-energy  physics  pigeonhole-markov  policy  polisci  politics  polynomials  popsci  population-genetics  preprint  presentation  princeton  probabilistic-method  probability  profile  proofs  puzzles  q-n-a  quantitative-qualitative  quantum-info  quantum  questions  quixotic  rand-approx  random  red-queen  reference  research-program  research  retrofit  rhetoric  rigor  risk  robust  roots  ryan-odonnell  sapiens  scale  science  sdp  sebastien-bubeck  selection  selfish-gene  social-choice  space  spatial  speed  speedometer  state-of-art  stats  stories  stream  strings  structure  study  stylized-facts  summary  survey  synthesis  talks  tcs  tcstariat  technology  thermo  threat-modeling  tim-roughgarden  time  toolkit  topology  ugc  uncertainty  unintended-consequences  unit  usa  vague  valiant  video  visuo  volo-avolo  wigderson  wiki  wild-ideas  workshop  xenobio  yoga  🌞  🎓  👳  🔬 

Copy this bookmark: