street-fighting   141

« earlier    

Lindy effect - Wikipedia
The Lindy effect is a theory that the future life expectancy of some non-perishable things like a technology or an idea is proportional to their current age, so that every additional period of survival implies a longer remaining life expectancy.[1] Where the Lindy effect applies, mortality rate decreases with time. In contrast, living creatures and mechanical things follow a bathtub curve where, after "childhood", the mortality rate increases with time. Because life expectancy is probabilistically derived, a thing may become extinct before its "expected" survival. In other words, one needs to gauge both the age and "health" of the thing to determine continued survival.
wiki  reference  concept  metabuch  ideas  street-fighting  planning  comparison  time  distribution  flux-stasis  history  measure  correlation  arrows  branches  pro-rata  manifolds  aging  stylized-facts  age-generation  robust  technology  thinking  cost-benefit  conceptual-vocab  methodology  threat-modeling  efficiency  neurons  tools  track-record 
3 days ago by nhaliday
Theory of Self-Reproducing Automata - John von Neumann
Fourth Lecture: THE ROLE OF HIGH AND OF EXTREMELY HIGH COMPLICATION

Comparisons between computing machines and the nervous systems. Estimates of size for computing machines, present and near future.

Estimates for size for the human central nervous system. Excursus about the “mixed” character of living organisms. Analog and digital elements. Observations about the “mixed” character of all componentry, artificial as well as natural. Interpretation of the position to be taken with respect to these.

Evaluation of the discrepancy in size between artificial and natural automata. Interpretation of this discrepancy in terms of physical factors. Nature of the materials used.

The probability of the presence of other intellectual factors. The role of complication and the theoretical penetration that it requires.

Questions of reliability and errors reconsidered. Probability of individual errors and length of procedure. Typical lengths of procedure for computing machines and for living organisms--that is, for artificial and for natural automata. Upper limits on acceptable probability of error in individual operations. Compensation by checking and self-correcting features.

Differences of principle in the way in which errors are dealt with in artificial and in natural automata. The “single error” principle in artificial automata. Crudeness of our approach in this case, due to the lack of adequate theory. More sophisticated treatment of this problem in natural automata: The role of the autonomy of parts. Connections between this autonomy and evolution.

- 10^10 neurons in brain, 10^4 vacuum tubes in largest computer at time
- machines faster: 5 ms from neuron potential to neuron potential, 10^-3 ms for vacuum tubes

https://en.wikipedia.org/wiki/John_von_Neumann#Computing
pdf  article  papers  essay  nibble  math  cs  computation  bio  neuro  neuro-nitgrit  scale  magnitude  comparison  acm  von-neumann  giants  thermo  phys-energy  speed  performance  time  density  frequency  hardware  ems  efficiency  dirty-hands  street-fighting  fermi  estimate  retention  physics  interdisciplinary  multi  wiki  links  people  🔬  atoms  automata  duplication  iteration-recursion  turing  complexity  measure  nature  technology  complex-systems  bits  information-theory  circuits  robust  structure  composition-decomposition  evolution  mutation  axioms  analogy  thinking  input-output  hi-order-bits  coding-theory  flexibility  rigidity 
april 2018 by nhaliday
The rate of return on everything - Marginal REVOLUTION
Here is what I learned from the paper itself:

1. Risky assets such as equities and residential real estate average about 7% gains per year in real terms.  Housing outperformed equity before WWII, vice versa after WWII.  In any case it is a puzzle that housing returns are less volatile but about at the same level as equity returns over a broader time span.
2. Equity and housing gains have a relatively low covariance.  Buy both!
3. Equity returns across countries have become increasingly correlated, housing returns not.
4. The return on real safe assets is much more volatile than you might think.
5. The equity premium is volatile too.
6. The authors find support for Piketty’s r > g, except near periods of war.  Furthermore, the gap between r and g does not seem to be correlated with the growth rate of the economy.

I found this to be one of the best and most interesting papers of the year.
econotariat  marginal-rev  commentary  study  summary  economics  macro  investing  ORFE  securities  data  street-fighting  objektbuch  scale  time-preference  cost-benefit  outcome-risk  housing  money  monetary-fiscal  debt  history  mostly-modern  world-war  trends  correlation  moments  growth-econ  inequality  piketty  stylized-facts  war  meta:war 
december 2017 by nhaliday
Autoignition temperature - Wikipedia
The autoignition temperature or kindling point of a substance is the lowest temperature at which it spontaneously ignites in normal atmosphere without an external source of ignition, such as a flame or spark. This temperature is required to supply the activation energy needed for combustion. The temperature at which a chemical ignites decreases as the pressure or oxygen concentration increases. It is usually applied to a combustible fuel mixture.

The time {\displaystyle t_{\text{ig}}} {\displaystyle t_{\text{ig}}} it takes for a material to reach its autoignition temperature {\displaystyle T_{\text{ig}}} {\displaystyle T_{\text{ig}}} when exposed to a heat flux {\displaystyle q''} {\displaystyle q''} is given by the following equation:
nibble  wiki  reference  concept  metrics  identity  physics  thermo  temperature  time  stock-flow  phys-energy  chemistry  article  street-fighting  fire  magnitude  data  list 
november 2017 by nhaliday
I can throw a baseball a lot further than a ping pong ball. I cannot throw a bowling ball nearly as far as a baseball. Is there an "optimal" weight for a ball to throw it as far as possible? : answers
If there are two balls with the same size, they will have the same drag force when traveling at the same speed.
Smaller balls will have less wetted area, and therefore less drag force acting on them
A ball with more mass will decelerate less given the same amount of drag.
The human hand has difficulty holding objects that are too large or too small.
I think that a human's throw is limited by the speed of the hand at the moment of release -- the object can't move faster than your hand when it's released.
A ball with more mass will also be more difficult for a human to throw. Thier arm will rotate slower and the object will have less velocity.
As such, you want the smallest ball that a human can comfortably hold, that is heavy for its size but still light with respect to a human's perspective. Bonus points for drag reduction tech.
Golf balls are surprisingly heavy given their size, and the dimples are designed to convert a laminar boundary layer into a turbulent one. Turbulent boundary layers grip the surface better, delaying flow separation, which is likely the most significant contribution to parasitic drag.
TL; DR: probably a golf ball.
nibble  reddit  social  discussion  q-n-a  physics  mechanics  fluid  street-fighting  biomechanics  extrema  optimization  atmosphere  curiosity  explanation 
september 2017 by nhaliday
Reynolds number - Wikipedia
The Reynolds number is the ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities, in what is known as a boundary layer in the case of a bounding surface such as the interior of a pipe. A similar effect is created by the introduction of a stream of higher velocity fluid, such as the hot gases from a flame in air. This relative movement generates fluid friction, which is a factor in developing turbulent flow. Counteracting this effect is the viscosity of the fluid, which as it increases, progressively inhibits turbulence, as more kinetic energy is absorbed by a more viscous fluid. The Reynolds number quantifies the relative importance of these two types of forces for given flow conditions, and is a guide to when turbulent flow will occur in a particular situation.[6]

Re = ρuL/μ

(inertial forces)/(viscous forces)
= (mass)(acceleration) / (dynamic viscosity)(velocity/distance)(area)
= (ρL^3)(v/t) / μ(v/L)L^2
= Re

NB: viscous force/area ~ μ du/dy is definition of viscosity
nibble  concept  metrics  definition  physics  mechanics  fluid  street-fighting  wiki  reference  atoms  history  early-modern  europe  the-great-west-whale  britain  science  the-trenches  experiment 
september 2017 by nhaliday
Europa, Enceladus, Moon Miranda | West Hunter
A lot of ice moons seem to have interior oceans, warmed by tidal flexing and possibly radioactivity.  But they’re lousy candidates for life, because you need free energy; and there’s very little in the interior oceans of such system.

It is possible that NASA is institutionally poor at pointing this out.
west-hunter  scitariat  discussion  ideas  rant  speculation  prediction  government  dirty-hands  space  xenobio  oceans  fluid  thermo  phys-energy  temperature  no-go  volo-avolo  physics  equilibrium  street-fighting  nibble  error  track-record  usa  bio  eden  cybernetics  complex-systems 
september 2017 by nhaliday
diffusion - Surviving under water in air bubble - Physics Stack Exchange
I get d≈400md≈400m.

It's interesting to note that this is independent of pressure: I've neglected pressure dependence of DD and human resilience to carbon dioxide, and the maximum safe concentration of carbon dioxide is independent of pressure, just derived from measurements at STP.

Finally, a bubble this large will probably rapidly break up due to buoyancy and Plateau-Rayleigh instabilities.
nibble  q-n-a  overflow  physics  mechanics  h2o  safety  short-circuit  tidbits  gedanken  fluid  street-fighting 
august 2017 by nhaliday
Historically significant lunar eclipses - Wikipedia
On 30 June 1503, Christopher Columbus beached his two last caravels and was stranded in Jamaica. The indigenous people of the island welcomed Columbus and his crew and fed them, but Columbus' sailors cheated and stole from the natives. After six months, the natives halted the food supply.[8]

Columbus had on board an almanac authored by Regiomontanus of astronomical tables covering the years 1475–1506; upon consulting the book, he noticed the date and the time of an upcoming lunar eclipse. He was able to use this information to his advantage. He requested a meeting for that day with the Cacique, the leader, and told him that his god was angry with the local people's treatment of Columbus and his men. Columbus said his god would provide a clear sign of his displeasure by making the rising full Moon appear "inflamed with wrath".

The lunar eclipse and the red moon appeared on schedule, and the indigenous people were impressed and frightened. The son of Columbus, Ferdinand, wrote that the people:

“ with great howling and lamentation came running from every direction to the ships laden with provisions, praying to the Admiral to intercede with his god on their behalf... ”
Columbus timed the eclipse with his hourglass, and shortly before the totality ended after 48 minutes, he told the frightened indigenous people that they were going to be forgiven.[8] When the moon started to reappear from the shadow of the Earth, he told them that his god had pardoned them.[9]
history  age-of-discovery  medieval  early-modern  europe  the-great-west-whale  conquest-empire  civilization  farmers-and-foragers  stories  cocktail  trivia  big-peeps  impro  persuasion  dark-arts  wiki  reference  space  nibble  leadership  sky  earth  cycles  navigation  street-fighting 
august 2017 by nhaliday
rotational dynamics - Why do non-rigid bodies try to increase their moment of inertia? - Physics Stack Exchange
This happens to isolated rotating system that is not a rigid body.

Inside such a body (for example, steel chain in free fall) the parts move relatively to each other and there is internal friction that dissipates kinetic energy of the system, while angular momentum is conserved. The dissipation goes on until the parts stop moving with respect to each other, so body rotates as a rigid body, even if it is not rigid by constitution.

The rotating state of the body that has the lowest kinetic energy for given angular momentum is that in which the body has the greatest moment of inertia (with respect to center of mass). For example, a long chain thrown into free fall will twist and turn until it is all straight and rotating as rigid body.

...

If LL is constant (net torque of external forces acting on the system is zero) and the constitution and initial conditions allow it, the system's dissipation will work to diminish energy until it has the minimum value, which happens for maximum IaIa possible.
nibble  q-n-a  overflow  physics  mechanics  tidbits  spatial  rigidity  flexibility  invariance  direction  stylized-facts  dynamical  volo-avolo  street-fighting  yoga 
august 2017 by nhaliday
Introduction to Scaling Laws
https://betadecay.wordpress.com/2009/10/02/the-physics-of-scaling-laws-and-dimensional-analysis/
http://galileo.phys.virginia.edu/classes/304/scaling.pdf

Galileo’s Discovery of Scaling Laws: https://www.mtholyoke.edu/~mpeterso/classes/galileo/scaling8.pdf
Days 1 and 2 of Two New Sciences

An example of such an insight is “the surface of a small solid is comparatively greater than that of a large one” because the surface goes like the square of a linear dimension, but the volume goes like the cube.5 Thus as one scales down macroscopic objects, forces on their surfaces like viscous drag become relatively more important, and bulk forces like weight become relatively less important. Galileo uses this idea on the First Day in the context of resistance in free fall, as an explanation for why similar objects of different size do not fall exactly together, but the smaller one lags behind.
nibble  org:junk  exposition  lecture-notes  physics  mechanics  street-fighting  problem-solving  scale  magnitude  estimate  fermi  mental-math  calculation  nitty-gritty  multi  scitariat  org:bleg  lens  tutorial  guide  ground-up  tricki  skeleton  list  cheatsheet  identity  levers  hi-order-bits  yoga  metabuch  pdf  article  essay  history  early-modern  europe  the-great-west-whale  science  the-trenches  discovery  fluid  architecture  oceans  giants  tidbits  elegance 
august 2017 by nhaliday

« earlier    

related tags

2014  2016-election  2016  80000-hours  ability-competence  academia  accuracy  acm  acmtariat  additive  adna  advice  africa  age-generation  age-of-discovery  aging  agri-mindset  agriculture  ai-control  ai  algorithms  alien-character  alignment  allodium  alt-inst  altruism  ama  amt  analogy  analysis  analytical-holistic  anglosphere  anthropic  anthropology  antiquity  aphorism  apollonian-dionysian  applications  arbitrage  archaeology  archaics  architecture  arms  arrows  article  asia  assortative-mating  atmosphere  atoms  automata  automation  axioms  backup  behavioral-gen  being-becoming  being-right  best-practices  better-explained  betting  biases  big-peeps  big-picture  bio  biodet  biomechanics  biophysical-econ  bits  boaz-barak  books  bostrom  bounded-cognition  branches  brands  britain  broad-econ  business  c:*  calculation  caltech  candidate-gene  capital  capitalism  causation  chart  cheatsheet  checklists  chemistry  china  circuits  civic  civilization  clarity  class  clever-rats  cliometrics  coalitions  cocktail  coding-theory  cog-psych  coming-apart  commentary  communication  comparison  compensation  competition  complement-substitute  complex-systems  complexity  composition-decomposition  computation  concentration-of-measure  concept  conceptual-vocab  concrete  confidence  confounding  conquest-empire  consilience  context  contracts  contrarianism  cool  cooperate-defect  core-rats  correlation  cost-benefit  counterexample  critique  crooked  cs  culture-war  culture  curiosity  current-events  cybernetics  cycles  dark-arts  data-science  data  database  dataset  dataviz  death  debt  decision-making  decision-theory  deep-materialism  defense  definite-planning  definition  demographics  density  dependence-independence  descriptive  detail-architecture  developing-world  differential  dimensionality  direction  dirty-hands  discovery  discrimination  discussion  distribution  divergence  drugs  duplication  dynamic  dynamical  dysgenics  early-modern  earth  econ-metrics  econometrics  economics  econotariat  eden  education  effect-size  effective-altruism  efficiency  elections  electromag  elegance  elite  embedded-cognition  embodied-pack  embodied  empirical  ems  endo-exo  endogenous-exogenous  energy-resources  engineering  enhancement  environment  epistemic  equilibrium  error  essay  essence-existence  estimate  ethanol  ethics  europe  evidence-based  evolution  examples  existence  expansionism  expectancy  experiment  expert-experience  expert  explanans  explanation  exposition  extrema  faq  farmers-and-foragers  fermi  feynman  fighting  finance  fire  fisher  flexibility  fluid  flux-stasis  flynn  food  foreign-policy  formal-values  fourier  frequency  frontier  futurism  gallic  game-theory  games  garett-jones  gavisti  gedanken  gelman  gender-diff  gender  gene-drift  gene-flow  genetic-load  genetics  genomics  geography  geometry  geopolitics  germanic  giants  gilens-page  gnon  gnxp  google  gotchas  government  gowers  gravity  gray-econ  great-powers  gregory-clark  ground-up  growth-econ  guide  gwas  gwern  h2o  haidt  hanson  hardware  hari-seldon  healthcare  heavy-industry  heuristic  hi-order-bits  higher-ed  history  hmm  homo-hetero  housing  howto  hsu  huge-data-the-biggest  human-capital  hypothesis-testing  ideas  identity  ieee  iidness  impact  impetus  impro  incentives  india  individualism-collectivism  industrial-revolution  inequality  info-dynamics  info-econ  info-foraging  infographic  information-theory  init  input-output  insight  instinct  integral  intelligence  interdisciplinary  interests  intersection-connectedness  intersection  intervention  intricacy  intuition  invariance  investing  iq  iron-age  iteration-recursion  japan  journos-pundits  judgement  knowledge  kumbaya-kult  labor  language  latent-variables  latin-america  law  leadership  lecture-notes  left-wing  len:long  len:short  lens  lesswrong  let-me-see  levers  lexical  limits  linear-models  liner-notes  links  list  local-global  lol  long-short-run  long-term  longevity  low-hanging  macro  magnitude  malthus  manifolds  maps  marginal-rev  marginal  markets  math.ca  math.co  math.cv  math  mathtariat  matrix-factorization  measure  measurement  mechanics  media  medicine  medieval  mediterranean  mena  mental-math  meta:medicine  meta:prediction  meta:rhetoric  meta:science  meta:war  metabuch  metameta  methodology  metric-space  metrics  micro  microfoundations  military  minimum-viable  mobility  models  modernity  moments  monetary-fiscal  money  morality  mostly-modern  multi  multiplicative  mutation  natural-experiment  nature  navigation  near-far  network-structure  neuro-nitgrit  neuro  neurons  new-religion  news  nibble  nihil  nitty-gritty  no-go  noise-structure  nonlinearity  nuclear  null-result  nutrition  objektbuch  oceans  old-anglo  opioids  optimization  order-disorder  orfe  org:biz  org:bleg  org:bv  org:data  org:foreign  org:junk  org:lite  org:mag  org:mat  org:ngo  org:popup  org:rec  org:sci  oscillation  outcome-risk  outliers  overflow  oxbridge  papers  paradox  parenting  pareto  parsimony  path-dependence  paying-rent  pdf  peace-violence  people  performance  personal-finance  persuasion  pharma  phys-energy  physics  pic  piketty  planning  plots  poast  policy  polisci  politics  poll  pop-diff  pop-structure  popsci  population-genetics  population  positivity  power-law  power  pragmatic  pre-2013  pre-ww2  prediction-markets  prediction  prepping  prioritizing  priors-posteriors  pro-rata  probability  problem-solving  project  proofs  properties  proposal  psychology  publishing  puzzles  q-n-a  qra  qtl  quality  quantitative-qualitative  questions  quotes  race  random-networks  random  ranking  rant  rat-pack  rationality  ratty  realness  realpolitik  recent-selection  reddit  reference  reflection  regression-to-mean  regression  regularizer  relativity  replication  retention  review  rhetoric  rhythm  rigidity  risk  robust  roots  russia  s:**  s:*  safety  sampling-bias  sapiens  scale  scaling-tech  scaling-up  scholar  science  scitariat  search  securities  selection  series  sex  shift  short-circuit  signal-noise  signaling  signum  similarity  simulation  singularity  sinosphere  skeleton  skunkworks  sky  sleuthin  social-choice  social-psych  social-science  social  society  sociology  space  spatial  speaking  spearhead  speculation  speed  speedometer  spock  spreading  ssc  stagnation  stats  status  stereotypes  stock-flow  stories  strategy  structure  study  stylized-facts  success  summary  supply-demand  symmetry  systematic-ad-hoc  tactics  tails  tcs  tcstariat  teaching  technocracy  technology  techtariat  temperature  tetlock  the-bones  the-classics  the-great-west-whale  the-trenches  the-west  the-world-is-just-atoms  theory-practice  thermo  thick-thin  thinking  threat-modeling  thucydides  tidbits  time-preference  time  todo  tools  top-n  track-record  trade  trees  trends  tricki  tricks  trivia  troll  truth  turing  tutorial  twitter  uncertainty  unit  urban-rural  urban  usa  vampire-squid  variance-components  visual-understanding  visualization  volo-avolo  von-neumann  vulgar  war  waves  wealth-of-nations  wealth  west-hunter  white-paper  wiki  wild-ideas  winner-take-all  wire-guided  wonkish  world-war  world  writing  xenobio  yoga  yvain  🌞  🎩  🔬  🖥  🤖 

Copy this bookmark:



description:


tags: