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The liar paradox

A favourite of our kids is to play opposites day. It usually starts with something simple like where we say “No, they can’t have chocolate for breakfast,” and they then announce that it’s opposites day so that means they can have chocolate for breakfast. Then I say, but if it’s opposites day then that means you just said it’s not opposites day. Then they say, if it’s not opposites day then what they said is true so it is opposites day. After a while we end up being late for school. This is a version of the liar paradox, also known as the Epimenides paradox after a chap from Crete who is supposed to have announced that all Cretans are liars. There are a bunch of versions of the paradox including the simpler one: this sentence is a lie. Some other paradoxes: Jevon’s paradox the coastline paradox the Abilene paradox…A favourite of our kids is to play opposites day. It usually starts with something simple like where we say “No, they can’t have chocolate for breakfast,” and they then announce that it’s opposites day so that means they can have chocolate for breakfast. Then I say, but if it’s opposites day then that means you just said it’s not opposites day. Then they say, if it’s not opposites day then what they said is true so it is opposites day. After a while we end up being late for school. This is a version of the liar paradox, also known as the Epimenides paradox after a chap from Crete who is supposed to have announced that all Cretans are liars. There are a bunch of versions of the paradox including the simpler one: this sentence is a lie. Some other paradoxes: Jevon’s paradox the coastline paradox the Abilene paradox

11 Apr 2020

The Bullwhip Effect

How small changes in customer demand can produce considerable disruption upstream in the supply chain. For instance, a sudden surge in the buying of toilet paper may cause retailers to put in larger orders to make sure they can keep up with demand. Manufacturers, in turn, may put in even larger orders for raw materials to make sure they don’t get caught out. In the meantime, customers had bought all the toilet paper they ever needed and demand suddenly dropped causing retailers to cancel all their orders, manufacturers to halt production and suppliers to be left with big stockpiles of unwanted raw materials. I learned about the bullwhip effect from Tomas Tunguz where he considers economic effects of the coronavirus. He explains it with a brewery example in his article on proxy metrics for startups.…How small changes in customer demand can produce considerable disruption upstream in the supply chain. For instance, a sudden surge in the buying of toilet paper may cause retailers to put in larger orders to make sure they can keep up with demand. Manufacturers, in turn, may put in even larger orders for raw materials to make sure they don’t get caught out. In the meantime, customers had bought all the toilet paper they ever needed and demand suddenly dropped causing retailers to cancel all their orders, manufacturers to halt production and suppliers to be left with big stockpiles of unwanted raw materials. I learned about the bullwhip effect from Tomas Tunguz where he considers economic effects of the coronavirus. He explains it with a brewery example in his article on proxy metrics for startups.

5 Apr 2020

What is the scale of solar system distances explained: show how big is the solar system, what is an astronomical unit and the distances between planets

Solar system planets: how big is the solar system?

It’s pretty hard to get to grips with the scale of the solar system. It's really, really, really big. To help process the vast distances within our system, astronomers use Astronomical Units where 1 AU is the distance of Earth from the Sun. If you see Venus in the night sky, our closest neighbour just 0.7 AU from the sun, it looks impossibly far away. But the further out you go, the more the distances multiply. Earth and Venus are practically on top of each other compared to Uranus and Neptune. Neptune is a full 30 times the distance between Earth and the Sun. Now think about the fact that our little solar system is over 250,000 AUs from our nearest star, which is, in turn, just one of many tucked away in a small corner of the Milky Way, which is only one of many galaxies that make up the known universe. It might be time to sit down. James O'Donoghue has made some brilliant videos about the solar system that explain this and more. This sketch, and plenty more in the Starry-eyed Surprises section, features in my book Big Ideas Little Pictures The original sketch of solar system sizes is on a paper background. Prints of the Paper background solar system sizes sketch Dark sky background solar system sizes sketch…It’s pretty hard to get to grips with the scale of the solar system. It's really, really, really big. To help process the vast distances within our system, astronomers use Astronomical Units where 1 AU is the distance of Earth from the Sun. If you see Venus in the night sky, our closest neighbour just 0.7 AU from the sun, it looks impossibly far away. But the further out you go, the more the distances multiply. Earth and Venus are practically on top of each other compared to Uranus and Neptune. Neptune is a full 30 times the distance between Earth and the Sun. Now think about the fact that our little solar system is over 250,000 AUs from our nearest star, which is, in turn, just one of many tucked away in a small corner of the Milky Way, which is only one of many galaxies that make up the known universe. It might be time to sit down. James O'Donoghue has made some brilliant videos about the solar system that explain this and more. This sketch, and plenty more in the Starry-eyed Surprises section, features in my book Big Ideas Little Pictures The original sketch of solar system sizes is on a paper background. Prints of the Paper background solar system sizes sketch Dark sky background solar system sizes sketch

28 Mar 2020

Equinox

On the equinox there is nearly exactly 12 hours of daylight and night — the day and night are perfectly balanced. On these days the sun rises almost due East and sets due West. The Spring equinox and Fall equinox are the transition between the seasons of Winter to Spring or Summer to Fall, depending on if your days are getting longer or shorter. The other seasons transition at the solstices. Technically, the equinox is the instant “the plane of Earth’s equator passes through the center of the Sun.” (wikipedia) This usually happens around the 20 March and 23 September. The equinox exists due to the tilt of the Earth. Also see: Seasons Solstice…On the equinox there is nearly exactly 12 hours of daylight and night — the day and night are perfectly balanced. On these days the sun rises almost due East and sets due West. The Spring equinox and Fall equinox are the transition between the seasons of Winter to Spring or Summer to Fall, depending on if your days are getting longer or shorter. The other seasons transition at the solstices. Technically, the equinox is the instant “the plane of Earth’s equator passes through the center of the Sun.” (wikipedia) This usually happens around the 20 March and 23 September. The equinox exists due to the tilt of the Earth. Also see: Seasons Solstice

21 Mar 2020

Flatten the Curve illustration: 4 different containment strategies for a contagion outbreak and their expected effect on the number of cases detected over time are shown through a series of distribution curves.

Flatten the curve of an outbreak

Writing this in the middle(?) of the coronavirus outbreak I thought it might be interesting to share these charts, created from the simulations in the excellent Washington Post article “Why outbreaks like the coronavirus spread exponentially, and how to ‘flatten the curve’” by Harry Stevens. The charts represent different strategies for containment and mitigation of the effects of a contagious outbreak. Trying to quarantine an area — where it is difficult to attain complete quarantine — delays the effect of an outbreak somewhat, but once released the impact is still significant with a potentially high peak of cases. Social-distancing — staying away from each other to reduce the chance of infecting others if you are infected and minimise the chance of infecting yourself — in both the bottom scenarios in the simulation manages to both delay the onset of an outbreak and reduce the peak. Not included in this simple simulation is that reducing peak infections in particular helps the healthcare system effectively treat and care for those who are infected, and look after its healthcare workers. When healthcare is not overwhelmed this further minimises both the spread of a disease and fatality rate. Read the article, run your own simulations, and maybe consider supporting the Washington Post, here: “Why outbreaks like the coronavirus spread exponentially, and how to 'flatten the curve’”. Disclaimer: I am not a public health professional. These charts are from my results of the simulations in the article and the simulations represent a simplified, though instructive I think, view of an outbreak and these containment methods. HT: Slava Kremerman…Writing this in the middle(?) of the coronavirus outbreak I thought it might be interesting to share these charts, created from the simulations in the excellent Washington Post article “Why outbreaks like the coronavirus spread exponentially, and how to ‘flatten the curve’” by Harry Stevens. The charts represent different strategies for containment and mitigation of the effects of a contagious outbreak. Trying to quarantine an area — where it is difficult to attain complete quarantine — delays the effect of an outbreak somewhat, but once released the impact is still significant with a potentially high peak of cases. Social-distancing — staying away from each other to reduce the chance of infecting others if you are infected and minimise the chance of infecting yourself — in both the bottom scenarios in the simulation manages to both delay the onset of an outbreak and reduce the peak. Not included in this simple simulation is that reducing peak infections in particular helps the healthcare system effectively treat and care for those who are infected, and look after its healthcare workers. When healthcare is not overwhelmed this further minimises both the spread of a disease and fatality rate. Read the article, run your own simulations, and maybe consider supporting the Washington Post, here: “Why outbreaks like the coronavirus spread exponentially, and how to 'flatten the curve’”. Disclaimer: I am not a public health professional. These charts are from my results of the simulations in the article and the simulations represent a simplified, though instructive I think, view of an outbreak and these containment methods. HT: Slava Kremerman

15 Mar 2020

Chindogu

Chindogu are inventions that are not really useful yet are not completely without use. They make sense, but you’d never use them. They are also, as a result, often really funny. This chindogu article gives some great examples while also sharing the 10 tenets of what makes chindogu, chindogu. Things like: there must be the spirit of anarchy — they represent freedom of thought and action. And they must exist — just the idea isn’t enough; they must be made. Apparently, the selfie stick was invented as chindogu but failed as people evidently actually found it useful — though you can still see why it might have started as chindogu. Also see: affordance, forcing function, and more genius from the Japanese: Tsundoku…Chindogu are inventions that are not really useful yet are not completely without use. They make sense, but you’d never use them. They are also, as a result, often really funny. This chindogu article gives some great examples while also sharing the 10 tenets of what makes chindogu, chindogu. Things like: there must be the spirit of anarchy — they represent freedom of thought and action. And they must exist — just the idea isn’t enough; they must be made. Apparently, the selfie stick was invented as chindogu but failed as people evidently actually found it useful — though you can still see why it might have started as chindogu. Also see: affordance, forcing function, and more genius from the Japanese: Tsundoku

7 Mar 2020

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