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u/lpetrich

r/EndFPTP r/latin r/IndoEuropean r/Metric r/linguisticshumor r/VintageApple r/BigFive r/Spaceexploration r/exoplanets
▲ 12 r/exoplanets

The Earth observed like an Exoplanet

What can one learn by observing the light curve of an exoplanet? Especially in several spectral bands. Here is some research on that, using the Earth as an example.

The DSCOVR satellite observes the Earth from Earth-Sun L1, about 1.5 million kilometers (gigameters) toward the Sun. It can take pictures in several wavelength bands, not just RGB, at wavelengths 317.5, 325, 340, 388, 443, 551, 680, 688, 764, and 779.5 nanometers: the visible range with some nearby ultraviolet and infrared. For simulated observations as an exoplanet, one integrates over the surface of the Earth.

The papers show pictures of the Earth in these different wavelengths. By comparing those pictures, one can recognize different kinds of features.

The first paper calculates for infrequent observations the likelihood of finding our planet's rotation rate. It's close to 1 for more frequent than 3 times a day, and declines to a small amount for one observation each 1.5 days.

The second paper finds the typical spectra of ocean, vegetation, desert, snow/ice, low clouds, and high clouds, and also does principal components analysis, a common data-mining technique, on observations. The first component is mainly for low clouds, the second component for ocean, vegetation, and desert, and the third and fourth components for high clouds. Snow/ice is like a mixture of low clouds and high clouds.

The third paper has a reconstructed surface map, though I could not follow how one gets from one dimension to two dimensions.

The fourth paper discusses an Earth Spectrum Simulator.

This kind of work should be extended to other Solar System celestial bodies, since we now have a good idea of the surfaces of most of the larger ones.

Simulations of Light Curves from Earth-like Exoplanets - Planetary Habitability Laboratory @ UPR Arecibo at the Internet Archive. I could not find any published version, but I verified the results with my own calculations. The simulations were done with RGB color bands, the most readily available sort of multiple wavelength bands.

The Earth is usually bluish, but when the Sahara Desert is well-illuminated and in good view, the Earth's color is neutral. So one can see that feature across interstellar space. Or more properly, a super Sahara, with that desert, the Arabian Desert, and to some extent, deserts in Iran and Central Asia.

Looking at other planetary-mass objects (planemos) or geophysical planets, the clouded-over ones - Venus, Jupiter, Saturn, Uranus, Neptune, and Titan - have little or no noticeable variation. Jupiter's Great Red Spot and Neptune's Great Dark Spot barely show up.

The solid-surface ones vary from Mercury, with very little variation, to Iapetus, with very strong variation. In between are Mars, the Moon, and the Earth.

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u/lpetrich — 4 days ago
▲ 18 r/IndoEuropean

Indo-European Population Expansion from Drinking Milk?

Language Dispersal Beyond Farming - Chapter 13, Milk and the Indo-Europeans, by Romain Garnier, Laurent Sagart and Benoît Sagot

Abstract:

>Recent evidence from archaeology and ancient DNA converge to indicate that the Yamnaya culture, often regarded as the bearer of the Proto-Indo-European language, underwent a strong population expansion in the late 4th and early 3rd millennia BCE. It suggests that the underlying reason for that expansion might be the then unique capacity to digest animal milk in adulthood. We examine the early Indo-European milk-related vocabulary to confirm the special role of animal milk in Indo-European expansions. We show that Proto-Indo-European did not have a specialized root for ‘to milk’ and argue that the IE root *h2melg̑- ‘to milk’ is secondary and post-Anatolian. We take this innovation as an indication of the novelty of animal milking in early Indo-European society. Together with a detailed study of language-specific innovations in this semantic field, we conclude that the ability to digest milk played an important role in boosting Proto-Indo-European demography.

An earlier thread here: Milk fueled Bronze Age expansion of ‘eastern cowboys’ into Europe | Science : r/IndoEuropean noting Milk fueled Bronze Age expansion of ‘eastern cowboys’ into Europe | Science | AAAS

The root *Hmelg- is present as a verb in Tocharian, Celtic, Italic, Germanic, Balto-Slavic, Albanian, and Greek, and as a noun in Tocharian, Celtic, Italic, and Germanic. The authors derive Latin lac(t-) from *Hmelg-, and also propose an etymology for that root: *h2emH- + *leg-

The first root they state to mean "to pour, collect", but Wiktionary states "to mow, reap", with English "to mow" as a descendant.

The second root is *leg- "to gather"

In Indo-Iranian, however, the root was replaced, because it sounded too similar to another root meaning "to rub". Also, for the noun, Greek has gala(kt-) and Armenian kat'n, both of obscure origin, and Lithuanian has pienas, from PIE *peyh2- "to swell, fat (n.)" Slavic *melko is either borrowed from Germanic or inherited.

Hittite has some odd difficulties, Its surviving documents all use the Sumerogram (Sumerian word) GA for "milk (n.)" and it had no word for "to milk", instead using some verb like lâ- "to let, make flow" with the noun -- "to make milk flow".

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u/lpetrich — 10 days ago
▲ 21 r/linguisticshumor

Hebrew is Greek? (WARNING: Total Crackpottery)

We've all seen hypotheses of language relationships from the well-supported to the absurd, but this one goes farther than every other one that I've seen:

Hebrew Is Greek By Joseph Yahuda : Joseph Yahuda : Free Download, Borrow, and Streaming : Internet Archive On pages 631-34 he states

>So that Hebrew is Greek, albeit somewhat altered Greek — Asiatic or Continental Greek, as distinct from European Greek — and it altered as to sound and form in an unparalleled manner, resulting in a differentiation which is peculiar and defies comparison.

In short, Hebrew is a dialect of Greek.

Which is totally absurd, since most dialects of languages closely resemble each other, and are often mutually intelligible. Hebrew and Greek are far too different from each other for that.

I remember an advocate of this theory who would get annoyed when I compared Greek to English and Hebrew to Arabic, because English and Arabic have homelands some distance from the Mediterranean Sea. He liked to point to Greek and Phoenician colonies in the Mediterranean and Black Seas around 2,500 years ago, as if that had anything to do with language relationship. Also parallel parts of the Bible from Masoretic Hebrew and Septuagint Greek, saying that the two were essentially the same language.

u/lpetrich — 16 days ago
▲ 5 r/BigFive

Subtraits of the Big Five

Is there any consensus on subtraits of the Big Five traits? Aspects, facets, ...

I've found some lists of them:

Here they are:

  • Extraversion
    • Aspects: Enthusiasm, Assertiveness
    • Facets 1: Positive Emotions, Excitement-Seeking, Activity Level, Assertiveness, Gregariousness, Warmth
    • Facets 2: Gregarious (sociable), Warm, Assertive, Active, Excitement-seeking, Positive emotionality
  • Openness/Intellect
    • Aspects: Openness, Intellect
    • Facets 1: Fantasy, Aesthetic Interest, Emotional Orientation, Experimentation, Intellectualism, Diversity-Tolerance
    • Facets 2: Fantasy prone, Open to feelings, Open to diverse behaviors, Open to new and different ideas, Open to various values and beliefs
  • Conscientiousness
    • Aspects: Industriousness, Orderliness
    • Facets 1: Self-Assurance, Orderliness, Dutifulness, Achievement-Striving, Self-Discipline, Prudence
    • Facets 2: Competent, Orderly, Dutiful, Achievement oriented, Self-disciplined, Deliberate
  • Agreeableness
    • Aspects: Compassion, Politeness
    • Facets 1: Trust, Earnestness, Altruism, Cooperation-Compliance, Modesty, Sympathy-Compassion
    • Facets 2: Trusting, Straightforward, Altruistic, Compliant, Modest, Tender-minded
  • Neuroticism
    • Aspects: Volatility, Withdrawal
    • Facets 1: Angst, Irritability, Immoderation, Self-Consciousness, Depressivity, Vulnerability
    • Facets 2: Anxious, Angry, Depressed, Self-conscious, Impulsive, Vulnerable

I used "angst" because a related a-word triggers a Rule 4 warning

Most of the two sets of facets can be matched onto each other, with only a few exceptions, and most of these facets are subtraits of some aspect.

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u/lpetrich — 2 months ago
▲ 1 r/Spaceexploration

Artificial Gravity: the Gravitron

We are adapted to our homeworld pulling down on us, to the point that lack of that pull causes trouble for us.

A solution is artificial gravity, and that takes the form of centrifugal force, from spinning all or part of a spacecraft or space station.

But can we do anything similar on the surface of a celestial body? There is an amusement-park ride that demonstrates a solution:

Gravitron - Wikipedia with a variety of names.

It has a cone segment that its riders get inside of with their backs against that segment, and this segment is made to rotate. When it rotates fast enough, the riders feel pulled directly downward relative to the nearby segment surface, from centrifugal force being strong enough for that.

The math:

  • Acceleration of gravity = g
  • Centrifugal acceleration c = r*w^2 at distance r from the spin axis with angular velocity w = (2*pi)/(period)

One needs a slope relative to horizontal of c/g or relative to vertical of g/c.

One can calculate the ideal shape of a Gravitron with some calculus and geometry:

(1/2)*r^2*w^2 = g*h for height h -- a paraboloid, a parabola rotated around its symmetry axis

The acceleration at each surface point is sqrt(g^2 + c^2).

One can make approximately constant acceleration by using a tower of multiple segments, and connecting them with ladders or staircases.

One will have to keep it safe for if the tower stops rotating, like have bulkheads.

Has anyone else thought of this idea?

Let's look at some numbers: Gravitational acceleration - Wikipedia relative to the Earth at 9.80665 m/s^2 (nominal value):

  • Earth 1, Moon 0.1655
  • Mercury 0.3770, Venus 0.9032, Mars 0.3895, Ceres 0.029
  • Jupiter* 2.640, Io 0.182, Europa 0.134, Ganymede 0.145, Callisto 0.126
  • Saturn* 1.139, Titan 0.138
  • Uranus* 0.917, Titania 0.039, Oberon 0.035
  • Neptune* 1.148, Triton 0.079
  • Pluto 0.0621, Eris 0.0814

The * is for cloud tops of places that are not very feasible for us to visit: the four outer planets.

On most of the worlds other than the outer planets, this stack of cone or paraboloid segments would be close to a cylinder. The exceptions:

  • Mars: vertical-relative slope 2/5
  • Venus: unnecessary, since its gravity is not much less than the Earth's
  • Earth: unnecessary
u/lpetrich — 2 months ago
▲ 11 r/latin

Using Adjectives for Genitive ("of") Relations

That seems to be common in Latin. Here are some examples:

Tusculanae Disputationes "Tusculan Disputations" by Cicero, instead of Disputationes in Tusculo "Disputations in Tusculum" or Disputationes Tusculi "Disputations of Tusculum".

Commodus named numerous things after himself, using the adjective Commodianus, like the renaming day, Dies Commodianus Commodus - Wikipedia Which he did instead of genitive Commodi, like Dies Commodi "Commodus's Day".

Ars "art, technique" was often used with an adjective, like (my translation) Ars Pactina "Art of the Deal", though a strict translation would be Ars Pacti.

u/lpetrich — 2 months ago
▲ 17 r/VintageApple

Gershwin, Copland's successor: what survives on it?

Copland (operating system) - Wikipedia linking to OS Directions: Marconi, Copland, and Gershwin - TidBITS I can find a lot on Apple's failed OS project Copland, but not much on its intended successor Gershwin.

From what I gather, Gershwin was to have full-scale preemptive multitasking and protected memory, with each GUI app having its own kernel process and running in its own memory space. That makes Gershwin on the level of NextStep and its successors, other Unix flavors like Linux and xBSD, and Windows NT and its successors.

A big problem is how to handle MacOS Classic apps. Copland did that by creating a virtual machine, the Blue Box, for MacOS Classic and its apps to run in. Any hint on what Gershwin was to do?

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u/lpetrich — 2 months ago
▲ 40 r/VintageApple

Taligent hopelessly unusable?

Taligent - Wikipedia started in the early 1990's, when Apple engineers were deciding on what features to implement in future versions of the MacOS. Easy but simple ones went onto blue index cards, while ambitious but difficult ones went onto pink ones. That led to "Pink" and then "Taligent" (talent + intelligent), a joint project with IBM. It was originally supposed to be an operating system, but there was not much interest in creating a new one, so it was reduced to an application shell, much like how NextStep ended up reduced to OpenStep. But even then, it did not get much interest.

Aaron Hillegass in his book "Cocoa Programming for Mac OS X" has this anecdote (p. 47):

>Once upon a time, there was a company called Taligent. Taligent was created by IBM and Apple to develop a set of tools and libraries like Cocoa. About the time Taligent reached the peak of its mindshare, I met one of its engineers at a trade show. I asked him to create a simple application for me: A window would appear with a button, and when that button was clicked, the words "Hello, World!" would appear in a text field. The engineer created a project and started subclassing madly: subclassing the window and the button and the event handler. Then he started generating code: dozens of lines to get the button and the text field on the window. After 45 minutes, I had to leave. The app still did not work. That day, I knew that the company was doomed. A couple of years later, Taligent quietly closed its doors forever.

Suggesting that Taligent was hopelessly unusable. Pointing in that direction is A Beginner's Guide to Developing with the Taligent Application Frameworks

>The conclusions of a three months learnability and usability study of Taligent Application frameworks are presented in terms of a preparatory guide for a novice user. It has been known that learnability of large object-oriented systems poses a serious obstacle to adoption of object-oriented technology. Taligent frameworks face this obstacle in particular. This paper was written to help you plan your learning path.

Noting that Taligent has 1940 object classes while NextStep has 128 and the Microsoft Foundation Classes 131. NextStep eventually became MacOS X.

I myself once tried that GUI "Hello, World" construction with several GUI toolkits:

  • MacOS Cocoa
  • Java
  • Python/TK
  • HTML/CSS/JavaScript

It took several minutes on each, though much of the time was in reading the documentation. I'm sure that someone with a lot of experience could do that much faster. For setup of the GUI widgets, I used Xcode's GUI builder for Cocoa, and did the other ones programmatically.

u/lpetrich — 2 months ago
▲ 10 r/VintageApple

Font demo text: "The quick brown fox jumps over the lazy dog 1234567890 times"

Something I recall from a 1990's version of the MacOS, most likely: this demo text for fonts in some font utility:

The quick brown fox jumps over the lazy dog 1234567890 times.

This is a "pangram", a phrase with at least one of every letter in it. The Apple version had a count added to it to demonstrate the decimal digits.

I also half-recall another MacOS font-demo pangram: "How razor-backed hogs..." but I don't recall all of it. Did anyone ever collect such demo texts?

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u/lpetrich — 2 months ago
▲ 9 r/Metric

Non-SI Units of the Very Small: Molecules, Atoms, Nuclei, Particles

Turning to the very small, we find non-SI units there also.

The angstrom (Å, A circle) is 10^(-10) m = 0.1 nm, and most elements' atoms have radii within a factor of 2 of an angstrom.

The fermi (fm) is 10^(-15) m, a femtometer, so "fermi" is another name for a SI unit, like "metric ton" or "tonne" for a megagram. It's around the radius of a nucleon; a proton and a neutron.

The barn is 10^(-28) m^2 or 100 fm^2. Reaction cross sections are often expressed in barns, often with SI prefixes.

The atomic mass unit or dalton (Da) is roughly the average mass per nucleon of light elements' atoms, like carbon or oxygen. It is currently defined as 1/12 the mass of a carbon-12 atom. "Dalton" is often given SI prefixes, and masses of biomolecules, like proteins and nucleic acids (DNA, RNA), are often reported in kilodaltons (kDa) or megadaltons (MDa).

The electron volt (eV) is the energy that an electron will gain when dropping through an electric-potential difference of 1 volt. It's not just an electron; it's anything with elementary charge 1, like a proton.

It is often given SI prefixes, and it is often used in atomic, nuclear, and particle physics. With the help of Einstein's famous equation, it is also used as a mass unit. Electrons have mass 511 kiloelectron volts (keV), protons have mass 938.3 megaelectron volts (MeV), (neutrons 939.6 MeV, dalton 931.5 MeV), top quarks have mass 173 gigaelectron volts (GeV), and the Large Hadron Collider can accelerate protons to energies around 6.8 teraelectron volts (TeV).

I am following the usual custom of omitting the Einstein mass-energy factor, (1/c^2).

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u/lpetrich — 3 months ago
▲ 12 r/EndFPTP

UK: Single Transferable Vote for English and Welsh Local Councils?

One of the United Kingdom's four countries, Scotland, has single transferable vote in its local councils: Single Transferable Vote (STV) – The City of Edinburgh Council

According to Single transferable vote - Wikipedia this dates back to 2007. Northern Ireland's local councils also use STV, along with NI's Parliament.

Local councils in the remaining two countries, England and Wales, continue to use FPTP, however, and Why we need to change the way we elect our councillors in England and Wales – Electoral Reform Society – ERS proposes changing that to STV.

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u/lpetrich — 3 months ago
▲ 1 r/Metric

Astronomers' Non-SI Units

Astronomers continue to use several non-SI units, though they have decided on SI values for nominal values of these units.

Sources:

Units:

  • Angle:
    • degree = (pi/180) radians
    • arcminute = (1/60) degrees
    • arcsecond = (1/60) arcminutes
  • Time:
    • minute = 60 SI second
    • hour = 60 minutes
    • day = 24 hours (~ Earth solar day)
    • year = 365.25 days (Julian year, ~ Earth year)
  • Distance:
    • astronomical unit (AU) = 149597870700 meters (~ Earth-Sun distance)
    • parsec (parallax second: pc) = (astronomical unit) / (arcsecond/radian)
  • Sun:
    • radius = 6.957*10^8 m
    • light flux at 1 AU = 1361 W/m^2
    • luminosity = 3.828*10^(26) W
    • temperature = 5770 K
    • G*mass = 1.3271244*10^(20) m^3/s^2
  • Earth:
    • equatorial radius = 6.3781*10^6 m
    • polar radius = 6.3568*10^6 m
    • G*mass = 3.986004*10^(14) m^3/s^2
  • Jupiter:
    • equatorial radius = 7.1492*10^7 m
    • polar radius = 6.6854*10^7 m
    • G*mass = 1.2668653*10^(17) m^3/s^2

The G in these definitions is the Newtonian gravitational constant. It is combined with the masses because this combination is sometimes measured to much greater accuracy than G itself.

Also, of planet radii, the equatorial radius is used unless specified otherwise.

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u/lpetrich — 3 months ago
▲ 1 r/BigFive

Between facets and domains: 10 aspects of the Big Five (2007) with a PDF copy on coauthor Jordan Peterson's page

The ten aspects, two for each factor, were found using principal components analysis on personality facets. Most facets had the highest loadings on their expected factors, and the exceptions had second highest loadings on these factors.

Each factor has two aspects:

  • Openness/Intellect: Openness, Intellect
  • Extraversion: Assertiveness, Enthusiasm
  • Conscientiousness: Industriousness, Orderliness
  • Agreeableness: Compassion, Politeness
  • Neuroticism: Volatility, Withdrawal

For each factor, its aspects have significant correlation, and its facets usually have significant loadings on at least one aspect.

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u/lpetrich — 4 months ago