2016-01-31 (Sunday)

Today, I learned that:

Astronomers in Babylon used mathematical methods already during centuries before the start of the Christian era to track movements of Jupiter. In order to do so, they were taking the first steps from geometry toward calculus to figure out the distance it moved across the sky. Such methods with trapezoides were only used much later in Europe, during the 14th century AD.

Babylon

Babylonian clay tablet. Photo: Trustees of the British Museum/Mathieu Ossendrijver

The proof for this can be found in four small clay tablets, which have been stored in the British museum for quite some time. However, it was only recently that Mathieu Ossendrijver from Humboldt University in Berlin was able to decypher their contents.

The interesting story can be found in the two references below.

… That’s what I learned in school!

Refs.:

1: Babylonians Were Using Geometry Centuries Earlier Than Thought

2: Babylonierna räknade också med grafer

+: What did you learn in school today ?

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2016-01-30 (Lördag)

Idag har jag lärt mig, att:

Snart kan man tjäna pengar utan att behöva jobba. I Finland diskuterar man sedan ett tag tillbaka att inrätta ett system med garanterad minimilön till sina innevånare. Det rör sig inte om så mycket pengar, men om man inte är statusjägare kanske det är tillräckligt.

Exempel på liknande, men mycket mer begränsade, system finns i Holland och Tyskland.

Allt detta kan ni höra mer om på SR P4 Världen idag. Där finns bl.a. också ett reportage från Colombia om hur man har börjat ännu ett krig, denna gång inte mot FARC-gerillan, utan Aedes aegypti, zika-myggan jag berättade om i torsdags, 2016-01-28.

Se en länk till programmet nedan.

… Tack för idag, slut för idag!

(This post in Swedish deals with getting paid without having to do anything in return.)

Refs.:

1: Få en lön utan att jobba

+: What did you learn in school today ?

2016-01-29 (Friday)

Today, I learned that:

There exists one more evidence of the negative consequencies of the American obsession to defend having a firearm for “personal protection”, instigated by the National Rifle Association. Here are excerpts from a podcast by Scientific American early this morning, stated by David Hemenway, director of the Harvard Injury Control Research Center:

hemenway

David Hemenway, photo by Harvard School of Public Health

“One of the things we know for sure in the United States is that a gun in the home increases the likelihood that someone in the home will die a violent death—from gun accidents, from a woman being murdered by a man in an intimate partner violence situation and particularly by suicide.

The gun violence discussion often seems to give short shrift to suicide, even though more than 60 percent of the approximately 32,000 annual U.S. firearms deaths are suicides.

The evidence is overwhelming, from case control studies and ecological studies. For example, why do we have very different suicide rates across cities, across states, across regions in the United States. To explain the differences in suicide rates across states, turns out it’s not well explained at all by differences in mental health, it’s not well explained at all by differences in the number of psychiatrists, it’s not even explained by differences in suicide ideation among the population or even suicide attempts. What really explains the difference in the United States across the populations is the number of guns. Because it’s gun suicide which is so different.

And someone who commits suicide with a gun very likely would not have either attempted or succeeded if the gun were not available. For example, a 2013 Swiss study tracked men after the size of the army was cut in half, effectively removing guns from half that group. The overall suicide rate went down, and the researchers estimated that only 22 percent of all the men who would have killed themselves with a gun if it had been available wound up committing the act by other means. The presence of the gun just makes it significantly easier to take your own life impulsively.”

Please see references below for complete coverage.

… That’s what I learned in school!

Refs.:

1: http://www.scientificamerican.com/podcast/episode/suicide-differences-by-region-related-to-gun-availability/

2: https://theforum.sph.harvard.edu/events/preventing-gun-violence/

+: https://www.youtube.com/watch?v=VucczIg98Gw

2016-01-28 (Torsdag)

Idag har jag lärt mig, att:

Ett virus som sprids med en mygga är ett stort problem som diskuteras idag på Världshälsoorganisationen. Zikaviruset framkallar zikafeber och myggan, som kallas Aedes aegypti, är också skyldig till att sprida andra febersjukdomar, såsom dengue feber, chikungunya och den välkända gula febern.

Här i Brasilien, där vi sedan några år tillbaka har sett en utbredning av dengue feber i många storstadsregioner börjar man nu också att misstänka att de många fallen av mikrocefali, där foster bara utvecklar förkrympta hjärnor, kan förorsakas av zikaviruset.

Bertolazzi

Don’t complain about the crisis. Work. Be creative. Do like Aedes aegypti, who started small and today is well succeeded with 3 products in the market

Dagens Vetandets Värld i SR P1 behandlade just zikaviruset under titeln “Zikaviruset utmanar Brasiliens forskare”. Jag rekommenderar varmt att de som är intresserade lyssnar på programmet, där man också tar upp frågorna om det kan vara farligt att resa till Brasilien under karnevalen och sommar-OS. Se referens 4 nedan.

Uppdatering 2016-01-30: Lotten Collin, SRs Latinamerikakorrespondent, rapporterar om kriget mot myggorna i Colombia. Se referens 5 nedan.

Uppdatering 2016-01-31: Statsepidemiolog Anders Tegnell på Folkhälsomyndigheten tillfogar fakta om historik och nuläge i dagens program av SR P1 Godmorgon, världen. Se referens 6 nedan.

Flamingos+

Flamingos in Parque das Aves, Foz de Iguaçu, PR, Brazil

Ytterligare en intressant iakttagelse, gjord av SR P1 Vetenskapsradions nyheter i morse, referens 7 nedan: Varför är en del flamingos skära? Jo, det beror på att deras föda är rik på karotenoider. I annat fall skulle de bara se slätstruket grå ut, och det skulle ju göra bilden på flamingona ovan bra mycket tristare.

Allra sist: Som du kan se av undertiteln till min blogg så har jag nu registrerat internetadressen “Medieborgaren.se”. Skriv in den adressen i din webbläsare och du kommer automatiskt att hamna i denna blogg.

… Slut för idag, tack för idag!

(This post deals with the zika virus that is spreading fast now, and which has led to an emergency at WHO. The Swedish radio program in reference 4 below contains quite some material in English.)

Refs.:

1: https://en.wikipedia.org/wiki/Zika_virus

2: https://en.wikipedia.org/wiki/Aedes_aegypti

3: https://en.wikipedia.org/wiki/Microcephaly

4: http://sverigesradio.se/sida/avsnitt/668073?programid=412

5: http://sverigesradio.se/sida/avsnitt/667807?programid=4734

6: http://sverigesradio.se/sida/artikel.aspx?programid=438&artikel=6357340

7: http://sverigesradio.se/sida/avsnitt/668053?programid=406

+: https://www.youtube.com/watch?v=VucczIg98Gw

2016-01-27 (Onsdag)

Idag lärde jag mig, att:

Idag är det många som intresserat följer med vad som händer i vårt kosmos. Många känner till Stephen Hawking och hans teorier om svarta hål, men visste ni att det redan i början på 1900-talet fanns en svensk som hörde till de stora inom astronomin?

Han hette Knut Lundmark, föddes i Älvsbyn i Norrbotten år 1889, och studerade vid Uppsala universitet, där han dokterade i astrofysik, på en avhandling om Andromedagalaxen. Han blev så småningom professor vid Lunds universitet, där han också var flitigt engagerad i olika populärvetenskapliga sammanhang. Under långa tider verkade han också vid olika observatorier i USA.

Hans största bidrag till astronomin, publicerat redan 1930, men avslöjat först under 2015, var att det i universum fanns mycken “mörk materia” som vi inte kunde förklara då, och det gäller faktiskt fortfarande. Och det var Knut som först postulerade att universum befinner sig i expansion, fem år innan Edwin Hubble.

KBL

Knut och Birgitta Lundmark. Foto: Norrbottens Museum

Knut och hans fru Birgitta brevväxlade mycket och ömsint under alla år som de var åtskilda av hans forskningsarbeten, och i radioprogrammet Släktband som sändes den 25 januari omtalas deras brevsamling, se referens 4 nedan, väl värt att lyssna på! Karin Tjernström på Norrbottens Museum rekommenderar också ett SR-program från 1948, där Harry Martinsson och Knut Lundmark samtalar om universum, referens 5 nedan.

… Slut för idag, tack för idag!

(This post in Swedish deals with the Swedish astronomer Knut Lundmark, the first scientist to propose the existence of dark materia and that the universe is expanding.)

Refs.:

1: Knut Lundmark på Wikipedia

2: Astronomiska Sällskapet Tycho Brahe om Knut Lundmark

3: Lundaprofessorn som upptäckte den mörka materian

4: Kärleksbrev i våra arkiv

5: Samtal om universum med Harry Martinson

+: What did you learn in school today ?

2016-01-26 (Tuesday)

Today, I learned that:

The custom of numbering the houses on a street, in order to facilitate visits, delivery of mail and parcels, etc., is said to have started in 1512, when there was built a new bridge in Paris, Pont Notre-Dame. On the bridge were built 68 equal houses and in order to distinguish one from another, they were given golden numbers on the outside, with odd numbers on one side and even numbers on the other side of the bridge. Initially, the purpose of this numbering was not so much to find the house for a visit, but sort of registration of property.

Pont Notre-Dame

La Joute des mariniers entre le Pont-Notre-Dame et le Pont-au-Change, painted by Nicolas-Jean-Baptiste Raguenet in 1752.

Today, practically all towns and cities have a numbering system, although there are differences. The article in Wikipedia, referenced below, deals with the numbering in most parts of the world, so I will not repeat it, but recommend it if you are interested in knowing further details. Here, I will only give some bullet points and also complement that article with some interesting pieces of information.

The basic rule is that the numbering starts in some place with high importance to the city, e.g. City hall, Main cathedral, etc. So the point of the street that is closest to this reference point receives the lowest number and the numbering then increases when you move away from the reference point. It is also very common that one side of the street, normally the left side, receives odd numbers and the other (right) side gets even numbers, just like in Paris in 1512. However, there are exceptions, where the odd numbers are used on the right side and even numbers on the left side.

The distribution of the numbers can be either sequential or by distance. The traditional, sequential distribution, such as 1, 3, 5, 7, 9, 11, … only indicates the relative position of a certain building compared to the reference point and other buildings on the same side of the street, but does not necessarily include information about the distances involved. This type of distribution is prevalent in Europe and many of its former colonies.

However, a different number distribution is very common in USA and Canada. It is basically the same as for sequential distribution, but usually all numbers are not present. The increase in the number used on a building, when compared to its neighbour located closer to the reference point, signifies roughly the distance (in yards) between the two. This distribution system goes hand in hand with the distribution of houses in blocks, and where each new block starts with a multiple of 100. Of course this means that it is easier to know how big is the distance still to be covered to the desired building, merely subtracting one number from the other.

Yesterday, I wrote about São Paulo, and since Brazil is not covered in this Wikipedia article, let me complement it with some information also from Brazil. The predominant system here is similar to the one used in North America, except that the distance is measured in meters, since Brazil uses the SI system. However, there are some Brazilian cities that use the sequential distribution, e.g. Santos, which celebrates its birthday today, being founded on January 26, 1546. However, the 8-year younger city, São Paulo, uses the distribution by distance, where most of the streets rely on Praça da Sé, the city center, as the reference point. However, in the Southern Zone of São Paulo, that until 1935 was the autonomous city of Santo Amaro, the numbering starts at the Cathedral of Santo Amaro.

… That’s what I learned in school!

Refs.:

1: House numbering

+: What did you learn in school today ?

2016-01-25 (Monday)

Today, I learned that:

There may still be hope for humanity. Even if there is big doubt if we will be able to slow down the global warming sufficiently, at least it seems that we are starting to take control over the growth in population. Let me start my reasoning in São Paulo, the biggest city in South America:

São Paulo celebrates it 462nd anniversary today with a local holiday. It was founded on January 25, 1554, under the name of São Paulo dos Campos de Piratininga, by a college of twelve Portuguese jesuit priests, the most well known being Manuel da Nóbrega and José de Anchieta. In 1560, It was renamed Vila de São Paulo, belonging to the Captaincy of São Vicente, whose main village was Brazil’s first one, founded in 1532. The coming centuries did not contribute much to history, but in 1711 São Paulo was converted from town to city. However, there were still few people living in the city. In 1872, there is an information that the population amounted to only 31.385 inhabitants. But from that point on has been a steep slope upward, with the current official number being 11.316.149 inhabitants (2011), and an estimate from the national statistics agency IBGE of 11.967.825 inhabitants in 2015.

In order for us to see the evolution of São Paulo from a village to one of the biggest cities in the world, let us look at the following table, which compares the growth of the population of São Paulo and the entirely world:

growthrate

As you can see, the current population growth rates are the lowest recorded during the last two centuries, so I believe it is a good sign that the world population will be able to take care of itself for quite some time yet.

Paulista++

Avenida Paulista, São Paulo, October 14, 1990

Returning to São Paulo, where I lived during 19 years old, and where both of my children were born: What can be more typical than characterizing them as “paulistas” (from the state of São Paulo), “paulistanos” (from the city of São Paulo), born on the biggest street Avenida Paulista (which also serves as a background to the photo above of my parents, taken in 1990), and, hopefully, also “são paulinos” (fans of São Paulo Football Club).

Finally, today is also the birthday of my sister-in-law Sônia, お誕生日おめでとう!

… That’s what I learned in school.

Refs.:

1: São Paulo on Wikipedia

2: São Paulo no IBGE

3: Population growth

4: World population

5: São Paulo FC

+: What did you learn in school today ?

2016-01-24 (Sunday)

Today, I learned that:

The largest prime number ever found was announced last Wednesday, January 20, 2016. So, what is a prime number and what is it good for?

A prime number is defined as a natural number (a positive integer) greather than 1, which cannot be evenly divided by any other natural number than 1 and itself. Examples of such numbers are 2, 3, 5, 7, 11, etc. It has been proven that there are an infinite quantity of prime numbers.

Prime numbers have been known for a long time, e.g. Euclid’s Elements (300 years BC) already mentions them, and in the beginning of the 17th century, a French monk named Marin Mersenne devised a formula, of the form 2p – 1, where p=1 is a prime number, to be used to check for unknown prime numbers. In fact, the largest prime number, which is exactly 274.207.281 − 1, consists of more than 22 million digits, and the search for bigger numbers continue. Please see the three references below for more information about prime numbers in general and also about the discovery of the currently biggest prime number, including an interview with Curtis Cooper, the leader of the project that discovered it.

One of the practical usages of prime numbers is in public-key cryptography, where two large prime numbers are multiplied to obtain a product that it is extremely difficult to factorize and thus break the code. But the search for these very big numbers does not seem to have any major practical use today, although they are very well fitted to test the speed performance of computer hardware.

And speaking about cryptography, having means of obtaining secure data streams is of course essential when we want to communicate data from one point to another. The current standard for data communication in the world is based upon what is called fourth-generation (4G) technology, and although it offers very fast rates of data communication, there are applications that demand even faster data transmission speeds. Examples of such applications are some components of the ‘Internet of Things’ (e.g. driver-less cars), and also in remote surgery, when the patient is in a hospital somewhere in the world, and at the same time the head surgeon is in a totally different place, performing the surgery via advanced, fast video and manipulation technologies.

For that and other purposes, last Friday, January 22, 2016, TeliaSonera and Ericsson announced that in 2018, they will start 5G networks in Stockholm and Tallinn. The rest of Sweden should see 5G in use in 2020.

Update on 2016-01-27: Today’s program of ‘Vetenskapens värld’ on Radio Sweden’s domestic channel P1 penetrates into the 5G technology. It will be a standard mostly used for machine to machine communication, and there are good hopes that one standard will be used everywhere on Earth, with speeds 100 times higher than the current 4G standard. See reference 7 below.

… That’s what I learned in school!

Refs.:

1: https://en.wikipedia.org/wiki/Prime_number

2: http://www.mersenne.org/primes/?press=M74207281

3: https://www.youtube.com/watch?v=q5ozBnrd5Zc

4: https://en.wikipedia.org/wiki/Public-key_cryptography

5: http://news.err.ee/v/scitech/fd66b9ee-1a44-4d13-aa6c-1f687812b2b8/

6: https://en.wikipedia.org/wiki/List_of_mobile_phone_generations

7: http://sverigesradio.se/sida/avsnitt/668029?programid=412

+: https://www.youtube.com/watch?v=VucczIg98Gw

2016-01-23 (Lördag)

Idag har jag åter lärt mig, att:

Dagens huvudämne är naturligtvis att fira vår Emilia på hennes namnsdag. Såsom gammal Emil, benämning på manliga teknologer på Chalmers, kan jag naturligtvis inte acceptera att man tog bort hennes egna namnsdag den 23 januari under år 2000. Inte för att jag har något emot att fira oss båda den 14 november, men visst är det bättre med två gasquer än en, inte sant?

I vilket fall som helst, idag vill jag fira Emilia med något som jag vet att hon tycker mycket om, nämligen choklad. Så vad ska jag välja, ljus eller mörk choklad, med eller utan fyllning, … ? För att klara av detta svåra val så tog jag hjälp av två nutida Emilior, som vet allt om choklad, nämligen Anna Högberg och Sandra Granberg. Läs och njut av lördagsmyset i referens 2 nedan.

… Tack för idag, slut för idag!

(This article in Swedish explains how to choose among all the types of chocolate.)

Refs.:

1: Emilias namnsdag 1975

2: Konsten att välja choklad

+: What did you learn in school today ?

2016-01-22 (Friday)

Today, I learned that:

Space lovers are having a week that is nothing else but fabulous. We already saw the first flower grown in zero gravity. And now, going from plant to planet, here comes other equally exciting news.

Astronomers at California Institute of Technology suggest that our solar system has a ninth planet. By measuring dwarf plants in the Kuiper Belt, farther away from us than Pluto, they suggest that their irregular movements may be due to influence by another, still unknown planet, that they call Planet Nine. If that is true, this planet is 5 to 10 times bigger than Earth and has an orbit around the Sun that takes 10.000 to 20.000 years to complete.

This reminds me of how Pluto was once discovered. In the 1840s, Urban Le Verrier predicted the position of Neptune by how Uranus had its orbit disturbed by another celestial object, and once Neptune had been discovered, there was a similar discussion about yet another planet, beyond Neptune. In 1909, Percival Lowell and William H. Pickering suggested the position of such a Planet X, until finally Pluto was confirmed by Clyde Tombaugh in 1930.

And speaking about planets, the coming two weeks will give us a festival of planets, when all five planets March, Venus, Jupiter, Mercury and Saturn will be aligned in the early morning sky and visible with naked eye! The reference below gives more details about that, and thanks also to Cecilia for the hint!

… That’s what I learned in school!

Refs.:

1: Astronomers may have found the Solar System’s 9th planet

2: Evidence for a distant giant planet in the solar system

3: Pluto

4: See all five naked-eye planets gathered in the morning sky

+: What did you learn in school today ?