cleanup the calendar events source; added a little text too

1 files changed, 454 insertions, 427 deletions

diff --git a/CosmicCalendarEvents.hs b/CosmicCalendarEvents.hs
index 224fbe8..90b5848 100644
--- a/CosmicCalendarEvents.hs
+++ b/CosmicCalendarEvents.hs
@@ -10,21 +10,67 @@ import NeatInterpolation
 
 import CosmicCalendar
 
+theYear, yearsBeforeCommonEra :: Integer -> NominalDiffTime
+theYear = yearsAgo . toRational . (currentYear -)
+yearsBeforeCommonEra = yearsAgo . toRational . ((+) (currentYear - 1))
+
 theCalendar :: Map NominalDiffTime CalendarEntry
 theCalendar = buildCalendar $
   [
-    CalendarEntry 0 Nothing "The Big Bang" "The universe begins" "" "",
+    CalendarEntry 0
+    Nothing
+    "The Big Bang"
+    "The universe begins"
+    ""
+    "",
+
     CalendarEntry (370 & thousandYears & afterBigBang)
-                  Nothing
-                  "Recombination"
-                  "The universe becomes transparent"
-                  recombinationDescription
-                  recombinationReferences,
+    Nothing
+    "Recombination"
+    "The universe becomes transparent"
+    [text|
+    At about 370,000 years,[3][4][5][6] neutral hydrogen atoms finish forming
+    ("recombination"), and as a result the universe also became transparent for
+    the first time. The newly formed atoms—mainly hydrogen and helium with
+    traces of lithium—quickly reach their lowest energy state (ground state) by
+    releasing photons ("photon decoupling"), and these photons can still be
+    detected today as the cosmic microwave background (CMB). This is the oldest
+    direct observation we currently have of the universe.
+    |]
+    [text|
+    https://en.wikipedia.org/wiki/Chronology_of_the_universe#The_very_early_universe
+
+    3. Tanabashi, M. 2018, p. 358, chpt. 21.4.1: "Big-Bang Cosmology" (Revised
+    September 2017) by Keith A. Olive and John A. Peacock.
+
+    4. Notes: Edward L. Wright's Javascript Cosmology Calculator (last modified
+    23 July 2018). With a default H 0 {\displaystyle H_{0}} H_{0} = 69.6 (based
+    on WMAP9+SPT+ACT+6dFGS+BOSS/DR11+H0/Riess) parameters, the calculated age of
+    the universe with a redshift of z = 1100 is in agreement with Olive and
+    Peacock (about 370,000 years).
+
+    5. Hinshaw, Weiland & Hill 2009. See PDF: page 45, Table 7, Age at
+    decoupling, last column. Based on WMAP+BAO+SN parameters, the age of
+    decoupling occurred 376971+3162−3167 years after the Big Bang.
+
+    6. Ryden 2006, pp. 194–195. "Without going into the details of the
+    non-equilibrium physics, let's content ourselves by saying, in round
+    numbers, zdec ≈ 1100, corresponding to a temperature Tdec ≈ 3000 K, when the
+    age of the universe was tdec ≈ 350,000 yr in the Benchmark Model. (...) The
+    relevant times of various events around the time of recombination are shown
+    in Table 9.1. (...) Note that all these times are approximate, and are
+    dependent on the cosmological model you choose. (I have chosen the Benchmark
+    Model in calculating these numbers.)"
+
+    https://en.wikipedia.org/wiki/Recombination_(cosmology)#cite_note-2
+    |],
+
     CalendarEntry (13.4 & billionYearsAgo) Nothing
     "The first observed star"
     ""
     "First Light Viewed Through the Rich Cluster Abell 2218"
     "https://sites.astro.caltech.edu/~rse/firstlight/",
+
     CalendarEntry (4.6 & billionYearsAgo) Nothing
     "Formation of the Sun"
     "The formation of the solar system begins"
@@ -36,291 +82,41 @@ theCalendar = buildCalendar $
     asteroids, and other small Solar System bodies formed.
     |]
     "https://en.wikipedia.org/wiki/Formation_and_evolution_of_the_Solar_System",
+
     CalendarEntry (4.54 & billionYearsAgo) Nothing
     "Formation of Earth"
     ""
-    earthDescription
-    "https://en.wikipedia.org/wiki/History_of_Earth#Solar_System_formation",
-
-    CalendarEntry (2.6 & millionYearsAgo) Nothing
-    "First Stone Tools"
-    "Mode I: The Oldowan Industry"
-    [text|
-    (Stones with sharp edges.)
-
-    The earliest known Oldowan tools yet found date from 2.6 million years ago,
-    during the Lower Palaeolithic period, and have been uncovered at Gona in
-    Ethiopia.[16] After this date, the Oldowan Industry subsequently spread
-    throughout much of Africa, although archaeologists are currently unsure
-    which Hominan species first developed them, with some speculating that it
-    was Australopithecus garhi, and others believing that it was in fact Homo
-    habilis.[17]
-
-    Homo habilis was the hominin who used the tools for most of the Oldowan in
-    Africa, but at about 1.9-1.8 million years ago Homo erectus inherited them.
-    The Industry flourished in southern and eastern Africa between 2.6 and 1.7
-    million years ago, but was also spread out of Africa and into Eurasia by
-    travelling bands of H. erectus, who took it as far east as Java by 1.8
-    million years ago and Northern China by 1.6 million years ago.
-    |]
-    "",
-
-    CalendarEntry (1.8 & millionYearsAgo) Nothing
-    "First major transition in stone tool technology"
-    "Mode II: The Acheulean Industry"
-    [text|
-    From the Konso Formation of Ethiopia, Acheulean hand-axes are dated to about
-    1.5 million years ago using radiometric dating of deposits containing
-    volcanic ashes.[6] Acheulean tools in South Asia have also been found to be
-    dated as far as 1.5 million years ago.[7] However, the earliest accepted
-    examples of the Acheulean currently known come from the West Turkana region
-    of Kenya and were first described by a French-led archaeology team.[8] These
-    particular Acheulean tools were recently dated through the method of
-    magnetostratigraphy to about 1.76 million years ago, making them the oldest
-    not only in Africa but the world.[9] The earliest user of Acheulean tools
-    was Homo ergaster, who first appeared about 1.8 million years ago. Not all
-    researchers use this formal name, and instead prefer to call these users
-    early Homo erectus.[3]
-    |]
-    "",
-
-    CalendarEntry (160 & thousandYearsAgo) Nothing
-    "Second major transition in stone tool technology"
-    "Mode III: The Levallois technique; The Mousterian Industry"
-    [text|
-    (Stone scrapers, knives, and projectile points)
-
-    The technique is first found in the Lower Palaeolithic but is most commonly
-    associated with the Neanderthal Mousterian industries of the Middle
-    Palaeolithic. In the Levant, the Levallois technique was also used by
-    anatomically modern humans during the Middle Stone Age. In North Africa, the
-    Levallois technique was used in the Middle Stone Age, most notably in the
-    Aterian industry to produce very small projectile points. While Levallois
-    cores do display some variability in their platforms, their flake production
-    surfaces show remarkable uniformity. As the Levallois technique is
-    counterintuitive, teaching the process is necessary and thus language is a
-    prerequisite for such technology.[2]
-
-    The Mousterian (or Mode III) is a techno-complex (archaeological industry)
-    of stone tools, associated primarily with the Neanderthals in Europe, and to
-    a lesser extent the earliest anatomically modern humans in North Africa and
-    West Asia. The Mousterian largely defines the latter part of the Middle
-    Paleolithic, the middle of the West Eurasian Old Stone Age. It lasted
-    roughly from 160,000 to 40,000 BP. If its predecessor, known as Levallois or
-    Levallois-Mousterian, is included, the range is extended to as early as c.
-    300,000–200,000 BP.[2] The main following period is the Aurignacian (c.
-    43,000–28,000 BP) of Homo sapiens.
-    |]
-    "",
-
-    CalendarEntry (115 & thousandYearsAgo) (Just $ 11.7 & thousandYearsAgo)
-    "The Ice Age begins"
-    "The Last Glacial Period"
-    [text|
-    The Last Glacial Period (LGP), also known colloquially as the last ice age
-    or simply ice age,[1] occurred from the end of the Eemian to the end of the
-    Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago. The
-    LGP is part of a larger sequence of glacial and interglacial periods known
-    as the Quaternary glaciation which started around 2,588,000 years ago and is
-    ongoing.[2] The definition of the Quaternary as beginning 2.58 million years
-    ago (Mya) is based on the formation of the Arctic ice cap. The Antarctic ice
-    sheet began to form earlier, at about 34 Mya, in the mid-Cenozoic
-    (Eocene–Oligocene extinction event). The term Late Cenozoic Ice Age is used
-    to include this early phase.[3]
-    |]
-    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
-
-    CalendarEntry (50 & thousandYearsAgo) Nothing
-    "Third major transition in stone tool technology"
-    "Mode IV: The Aurignacian Industry"
-    [text|
-    The widespread use of long blades (rather than flakes) of the Upper
-    Palaeolithic Mode 4 industries appeared during the Upper Palaeolithic
-    between 50,000 and 10,000 years ago, although blades were produced in small
-    quantities much earlier by Neanderthals.[20] The Aurignacian culture seems
-    to have been the first to rely largely on blades.[21] The use of blades
-    exponentially increases the efficiency of core usage compared to the
-    Levallois flake technique, which had a similar advantage over Acheulean
-    technology which was worked from cores.
-    |]
-    "https://en.wikipedia.org/wiki/Stone_tool#Mode_IV:_The_Aurignacian_Industry",
-
-    CalendarEntry (35 & thousandYearsAgo) Nothing
-    "Last major transition in stone tool technology"
-    "Mode V: The Microlithic Industries"
-    [text|
-    Mode 5 stone tools involve the production of microliths, which were
-    used in composite tools, mainly fastened to a shaft.[22] Examples include
-    the Magdalenian culture. Such a technology makes much more efficient use of
-    available materials like flint, although required greater skill in
-    manufacturing the small flakes. Mounting sharp flint edges in a wood or bone
-    handle is the key innovation in microliths, essentially because the handle
-    gives the user protection against the flint and also improves leverage of
-    the device.
-    |]
-    "https://en.wikipedia.org/wiki/Stone_tool#Mode_V:_The_Microlithic_Industries"
-    ,
-
-    CalendarEntry (12 & thousandYearsAgo) Nothing
-    "Agriculture leads to permanent settlements"
-    "Neolithic age (\"new stone age\")"
-    [text|
-    Wild grains were collected and eaten from at least 105,000 years ago.[2]
-    However, domestication did not occur until much later. The earliest evidence
-    of small-scale cultivation of edible grasses is from around 21,000 BC with
-    the Ohalo II people on the shores of the Sea of Galilee.[3] By around 9500
-    BC, the eight Neolithic founder crops – emmer wheat, einkorn wheat, hulled
-    barley, peas, lentils, bitter vetch, chickpeas, and flax – were cultivated
-    in the Levant.[4] Rye may have been cultivated earlier, but this claim
-    remains controversial.[5] Rice was domesticated in China by 6200 BC[6] with
-    earliest known cultivation from 5700 BC, followed by mung, soy and azuki
-    beans. Rice was also independently domesticated in West Africa and
-    cultivated by 1000 BC.[7][8] Pigs were domesticated in Mesopotamia around
-    11,000 years ago, followed by sheep. Cattle were domesticated from the wild
-    aurochs in the areas of modern Turkey and India around 8500 BC. Camels were
-    domesticated late, perhaps around 3000 BC.
-    |]
-    "https://en.wikipedia.org/wiki/History_of_agriculture",
-
-    CalendarEntry (6.5 & thousandYearsAgo) Nothing
-    "First copper tools"
-    ""
-    ""
-    "",
-
-    CalendarEntry (5.3 & thousandYearsAgo) Nothing
-    "First bronze tools, first written language"
-    "The Bronze Age"
-    ""
-    "",
-
-    CalendarEntry (3000 & yearsBeforeCommonEra) (Just $ 2350 & yearsBeforeCommonEra)
-    "Corded Ware culture"
-    "Indo-European languages spread across Europe and Asia"
-    [text|
-    The Corded Ware culture comprises a broad archaeological horizon of Europe
-    between ca. 3000 BCE – 2350 BCE, thus from the late Neolithic, through the
-    Copper Age, and ending in the early Bronze Age.[2] Corded Ware culture
-    encompassed a vast area, from the contact zone between the Yamnaya culture
-    and the Corded Ware culture in south Central Europe, to the Rhine on the
-    west and the Volga in the east, occupying parts of Northern Europe, Central
-    Europe and Eastern Europe.[2][3] The Corded Ware culture is thought to have
-    originated from the westward migration of Yamnaya-related people from the
-    steppe-forest zone into the territory of late Neolithic European cultures
-    such as the Globular Amphora and Funnelbeaker cultures,[4][5][6] and is
-    considered to be a likely vector for the spread of many of the Indo-European
-    languages in Europe and Asia.[1][7][8][9]
-
-    Corded Ware encompassed most of continental northern Europe from the Rhine
-    on the west to the Volga in the east, including most of modern-day Germany,
-    the Netherlands, Denmark, Poland, Lithuania, Latvia, Estonia, Belarus, Czech
-    Republic, Austria, Hungary, Slovakia, Switzerland, northwestern Romania,
-    northern Ukraine, and the European part of Russia, as well as coastal Norway
-    and the southern portions of Sweden and Finland.[2] In the Late
-    Eneolithic/Early Bronze Age, it encompassed the territory of nearly the
-    entire Balkan Peninsula, where Corded Ware mixed with other steppe
-    elements.[11]
-
-    Archaeologists note that Corded Ware was not a "unified culture," as Corded
-    Ware groups inhabiting a vast geographical area from the Rhine to Volga seem
-    to have regionally specific subsistence strategies and economies.[2]: 226 
-    There are differences in the material culture and in settlements and
-    society.[2] At the same time, they had several shared elements that are
-    characteristic of all Corded Ware groups, such as their burial practices,
-    pottery with "cord" decoration and unique stone-axes.[2]
-    |]
-    "",
-
-    CalendarEntry (2800 & yearsBeforeCommonEra) (Just $ 1800 & yearsBeforeCommonEra)
-    "Bell Beaker culture"
-    [text|
-    copper daggers, v-perforated buttons, stone wrist-guards
-    copper, bronze, and gold working
-    long-distance exchange networks, archery
-    social stratification and the emergence of regional elites
-    |]
-    [text|
-    The Bell Beaker culture (also described as the Bell Beaker complex or Bell
-    Beaker phenomenon) is an archaeological culture named after the
-    inverted-bell beaker drinking vessel used at the very beginning of the
-    European Bronze Age. Arising from around 2800 BC, it lasted in Britain until
-    as late as 1800 BC[1][2] but in continental Europe only until 2300 BC, when
-    it was succeeded by the Unetice culture. The culture was widely dispersed
-    throughout Western Europe, being present in many regions of Iberia and
-    stretching eastward to the Danubian plains, and northward to the islands of
-    Great Britain and Ireland, and was also present in the islands of Sicily and
-    Sardinia and some small coastal areas in north-western Africa. The Bell
-    Beaker phenomenon shows substantial regional variation, and a study[3] from
-    2018 found that it was associated with genetically diverse populations.
-
-    In its mature phase, the Bell Beaker culture is understood as not only a
-    collection of characteristic artefact types, but a complex cultural
-    phenomenon involving metalwork in copper and gold, long-distance exchange
-    networks, archery, specific types of ornamentation, and (presumably) shared
-    ideological, cultural and religious ideas, as well as social stratification
-    and the emergence of regional elites.[6][7] A wide range of regional
-    diversity persists within the widespread late Beaker culture, particularly
-    in local burial styles (including incidences of cremation rather than
-    burial), housing styles, economic profile, and local ceramic wares
-    (Begleitkeramik). Nonetheless, according to Lemercier (2018) the mature
-    phase of the Beaker culture represents "the appearance of a kind of Bell
-    Beaker civilization of continental scale."[8]
-
-    Bell Beaker people took advantage of transport by sea and rivers, creating a
-    cultural spread extending from Ireland to the Carpathian Basin and south
-    along the Atlantic coast and along the Rhône valley to Portugal, North
-    Africa, and Sicily, even penetrating northern and central Italy.[50] Its
-    remains have been found in what is now Portugal, Spain, France (excluding
-    the central massif), Ireland and Great Britain, the Low Countries and
-    Germany between the Elbe and Rhine, with an extension along the upper Danube
-    into the Vienna Basin (Austria), Hungary and the Czech Republic, with
-    Mediterranean outposts on Sardinia and Sicily; there is less certain
-    evidence for direct penetration in the east.
-    |]
-    "https://en.wikipedia.org/wiki/Bell_Beaker_culture",
-
-    CalendarEntry (11.7 & thousandYearsAgo) Nothing
-    "Ice Age ends"
-    ""
-    ""
-    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
-
-    CalendarEntry (1600 & yearsBeforeCommonEra) Nothing
-    "Dynastic China"
-    "History begins"
     [text|
-    The earliest known written records of the history of China date from as
-    early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the king
-    Wu Ding's reign
+    The standard model for the formation of the Solar System (including the
+    Earth) is the solar nebula hypothesis.[23] In this model, the Solar System
+    formed from a large, rotating cloud of interstellar dust and gas called the
+    solar nebula. It was composed of hydrogen and helium created shortly after
+    the Big Bang 13.8 Ga (billion years ago) and heavier elements ejected by
+    supernovae. About 4.5 Ga, the nebula began a contraction that may have been
+    triggered by the shock wave from a nearby supernova.[24] A shock wave would
+    have also made the nebula rotate. As the cloud began to accelerate, its
+    angular momentum, gravity, and inertia flattened it into a protoplanetary
+    disk perpendicular to its axis of rotation. Small perturbations due to
+    collisions and the angular momentum of other large debris created the means
+    by which kilometer-sized protoplanets began to form, orbiting the nebular
+    center.[25]
 
-    The state-sponsored Xia–Shang–Zhou Chronology Project dated them from c.
-    1600 to 1046 BC based on the carbon 14 dates of the Erligang site.
+    The center of the nebula, not having much angular momentum, collapsed
+    rapidly, the compression heating it until nuclear fusion of hydrogen into
+    helium began. After more contraction, a T Tauri star ignited and evolved
+    into the Sun. Meanwhile, in the outer part of the nebula gravity caused
+    matter to condense around density perturbations and dust particles, and the
+    rest of the protoplanetary disk began separating into rings. In a process
+    known as runaway accretion, successively larger fragments of dust and debris
+    clumped together to form planets.[25] Earth formed in this manner about 4.54
+    billion years ago (with an uncertainty of 1%)[26][27][4] and was largely
+    completed within 10–20 million years.[28] The solar wind of the newly formed
+    T Tauri star cleared out most of the material in the disk that had not
+    already condensed into larger bodies. The same process is expected to
+    produce accretion disks around virtually all newly forming stars in the
+    universe, some of which yield planets.[29]
     |]
-    "",
-
-    CalendarEntry (theYear 1492) Nothing
-    "Columbus arrives in America"
-    ""
-    ""
-    "",
-
-    CalendarEntry (theYear 570) Nothing
-    "Muhammad born"
-    ""
-    ""
-    "",
-
-    CalendarEntry (6 & yearsBeforeCommonEra) Nothing
-    "Christ born"
-    ""
-    ""
-    "",
-
-    CalendarEntry (480 & yearsBeforeCommonEra) Nothing
-    "Old Testament, Buddha"
-    ""
-    ""
-    "",
+    "https://en.wikipedia.org/wiki/History_of_Earth#Solar_System_formation",
 
     CalendarEntry (8.8 & billionYearsAgo) Nothing
     "Thin disk of the Milky Way Galaxy"
@@ -338,6 +134,67 @@ theCalendar = buildCalendar $
     |]
     "",
 
+    CalendarEntry (4.4 & billionYearsAgo) Nothing
+    "Formation of the moon"
+    "A collision of the planet Theia with Earth creates the moon"
+    [text|
+    Astronomers think the collision between Earth and Theia happened at about
+    4.4 to 4.45 bya; about 0.1 billion years after the Solar System began to
+    form.[15][16] In astronomical terms, the impact would have been of moderate
+    velocity. Theia is thought to have struck Earth at an oblique angle when
+    Earth was nearly fully formed. Computer simulations of this "late-impact"
+    scenario suggest an initial impactor velocity at infinity below 4 kilometres
+    per second (2.5 mi/s), increasing as it fell to over 9.3 km/s (5.8 mi/s) at
+    impact, and an impact angle of about 45°.[17] However, oxygen isotope
+    abundance in lunar rock suggests "vigorous mixing" of Theia and Earth,
+    indicating a steep impact angle.[3][18] Theia's iron core would have sunk
+    into the young Earth's core, and most of Theia's mantle accreted onto
+    Earth's mantle. However, a significant portion of the mantle material from
+    both Theia and Earth would have been ejected into orbit around Earth (if
+    ejected with velocities between orbital velocity and escape velocity) or
+    into individual orbits around the Sun (if ejected at higher velocities).
+    Modelling[19] has hypothesised that material in orbit around Earth may have
+    accreted to form the Moon in three consecutive phases; accreting first from
+    the bodies initially present outside Earth's Roche limit, which acted to
+    confine the inner disk material within the Roche limit. The inner disk
+    slowly and viscously spread back out to Earth's Roche limit, pushing along
+    outer bodies via resonant interactions. After several tens of years, the
+    disk spread beyond the Roche limit, and started producing new objects that
+    continued the growth of the Moon, until the inner disk was depleted in mass
+    after several hundreds of years.
+    |]
+    [text|
+    https://en.wikipedia.org/wiki/Giant-impact_hypothesis#Basic_model
+    https://www.psi.edu/epo/moon/moon.html
+    |],
+
+    CalendarEntry (3.77 & billionYearsAgo) Nothing
+    "Life on Earth"
+    ""
+    [text|
+    The earliest time for the origin of life on Earth is at least 3.77 billion
+    years ago, possibly as early as 4.28 billion years,[2] or even 4.41 billion
+    years[4][5]—not long after the oceans formed 4.5 billion years ago, and
+    after the formation of the Earth 4.54 billion years ago.[2][3][6][7]
+    |]
+    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
+
+    CalendarEntry (3.42 & billionYearsAgo) Nothing
+    "Earliest known life on Earth"
+    "The fossil record begins"
+    [text|
+    The earliest known life forms on Earth are putative fossilized
+    microorganisms found in hydrothermal vent precipitates, considered to be
+    about 3.42 billion years old.[1][2] The earliest time for the origin of life
+    on Earth is at least 3.77 billion years ago, possibly as early as 4.28
+    billion years,[2] or even 4.41 billion years[4][5]—not long after the oceans
+    formed 4.5 billion years ago, and after the formation of the Earth 4.54
+    billion years ago.[2][3][6][7] The earliest direct evidence of life on Earth
+    is from microfossils of microorganisms permineralized in
+    3.465-billion-year-old Australian Apex chert rocks.[8][9]
+    |]
+    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
+
     CalendarEntry (3.4 & billionYearsAgo) Nothing
     "First photosynthetic bacteria"
     "(Still no Oxygen)"
@@ -408,6 +265,27 @@ theCalendar = buildCalendar $
     https://en.wikipedia.org/wiki/Great_Oxidation_Event
     |],
 
+    CalendarEntry (2.05 & billionYearsAgo) Nothing
+    "Eukaryotic cells"
+    "Cells with nucleus (inner membrane holding DNA)"
+    [text|
+    Eukaryotes (/juːˈkærioʊts, -əts/) are organisms whose cells have a nucleus
+    enclosed within a nuclear envelope.[1][2][3] They belong to the group of
+    organisms Eukaryota or Eukarya; their name comes from the Greek εὖ (eu,
+    "well" or "good") and κάρυον (karyon, "nut" or "kernel").[4] The domain
+    Eukaryota makes up one of the three domains of life; bacteria and archaea
+    (both prokaryotes) make up the other two domains.[5][6] The eukaryotes are
+    usually now regarded as having emerged in the Archaea or as a sister of the
+    Asgard archaea.[7][8] This implies that there are only two domains of life,
+    Bacteria and Archaea, with eukaryotes incorporated among archaea.[9][10]
+    Eukaryotes represent a small minority of the number of organisms;[11]
+    however, due to their generally much larger size, their collective global
+    biomass is estimated to be about equal to that of prokaryotes.[11]
+    Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the
+    Proterozoic eon, likely as flagellated phagotrophs.[12][13]
+    |]
+    "https://en.wikipedia.org/wiki/Eukaryote",
+
     CalendarEntry (1.2 & billionYearsAgo) Nothing
     "Red and brown algae"
     ""
@@ -446,54 +324,6 @@ theCalendar = buildCalendar $
     |]
     "https://www.scientificamerican.com/article/timeline-of-photosynthesis-on-earth/",
 
-    CalendarEntry (2.05 & billionYearsAgo) Nothing
-    "Eukaryotic cells"
-    "Cells with nucleus (inner membrane holding DNA)"
-    [text|
-    Eukaryotes (/juːˈkærioʊts, -əts/) are organisms whose cells have a nucleus
-    enclosed within a nuclear envelope.[1][2][3] They belong to the group of
-    organisms Eukaryota or Eukarya; their name comes from the Greek εὖ (eu,
-    "well" or "good") and κάρυον (karyon, "nut" or "kernel").[4] The domain
-    Eukaryota makes up one of the three domains of life; bacteria and archaea
-    (both prokaryotes) make up the other two domains.[5][6] The eukaryotes are
-    usually now regarded as having emerged in the Archaea or as a sister of the
-    Asgard archaea.[7][8] This implies that there are only two domains of life,
-    Bacteria and Archaea, with eukaryotes incorporated among archaea.[9][10]
-    Eukaryotes represent a small minority of the number of organisms;[11]
-    however, due to their generally much larger size, their collective global
-    biomass is estimated to be about equal to that of prokaryotes.[11]
-    Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the
-    Proterozoic eon, likely as flagellated phagotrophs.[12][13]
-    |]
-    "https://en.wikipedia.org/wiki/Eukaryote",
-
-    CalendarEntry (3.77 & billionYearsAgo) Nothing
-    "Life on Earth"
-    ""
-    [text|
-    The earliest time for the origin of life on Earth is at least 3.77 billion
-    years ago, possibly as early as 4.28 billion years,[2] or even 4.41 billion
-    years[4][5]—not long after the oceans formed 4.5 billion years ago, and
-    after the formation of the Earth 4.54 billion years ago.[2][3][6][7]
-    |]
-    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
-
-    CalendarEntry (3.42 & billionYearsAgo) Nothing
-    "Earliest known life on Earth"
-    ""
-    [text|
-    The earliest known life forms on Earth are putative fossilized
-    microorganisms found in hydrothermal vent precipitates, considered to be
-    about 3.42 billion years old.[1][2] The earliest time for the origin of life
-    on Earth is at least 3.77 billion years ago, possibly as early as 4.28
-    billion years,[2] or even 4.41 billion years[4][5]—not long after the oceans
-    formed 4.5 billion years ago, and after the formation of the Earth 4.54
-    billion years ago.[2][3][6][7] The earliest direct evidence of life on Earth
-    is from microfossils of microorganisms permineralized in
-    3.465-billion-year-old Australian Apex chert rocks.[8][9]
-    |]
-    "https://en.wikipedia.org/wiki/Earliest_known_life_forms",
-
     CalendarEntry (750 & millionYearsAgo) Nothing
     "Bones and shells"
     ""
@@ -872,114 +702,311 @@ theCalendar = buildCalendar $
     https://www.khanacademy.org/humanities/world-history/world-history-beginnings/origin-humans-early-societies/a/where-did-humans-come-from
     |],
 
-    CalendarEntry (4.4 & billionYearsAgo) Nothing
-    "Formation of the moon"
-    "A collision of the planet Theia with Earth creates the moon"
+    CalendarEntry (600 & millionYearsAgo) Nothing
+    "Multicellular life"
+    ""
     [text|
-    Astronomers think the collision between Earth and Theia happened at about
-    4.4 to 4.45 bya; about 0.1 billion years after the Solar System began to
-    form.[15][16] In astronomical terms, the impact would have been of moderate
-    velocity. Theia is thought to have struck Earth at an oblique angle when
-    Earth was nearly fully formed. Computer simulations of this "late-impact"
-    scenario suggest an initial impactor velocity at infinity below 4 kilometres
-    per second (2.5 mi/s), increasing as it fell to over 9.3 km/s (5.8 mi/s) at
-    impact, and an impact angle of about 45°.[17] However, oxygen isotope
-    abundance in lunar rock suggests "vigorous mixing" of Theia and Earth,
-    indicating a steep impact angle.[3][18] Theia's iron core would have sunk
-    into the young Earth's core, and most of Theia's mantle accreted onto
-    Earth's mantle. However, a significant portion of the mantle material from
-    both Theia and Earth would have been ejected into orbit around Earth (if
-    ejected with velocities between orbital velocity and escape velocity) or
-    into individual orbits around the Sun (if ejected at higher velocities).
-    Modelling[19] has hypothesised that material in orbit around Earth may have
-    accreted to form the Moon in three consecutive phases; accreting first from
-    the bodies initially present outside Earth's Roche limit, which acted to
-    confine the inner disk material within the Roche limit. The inner disk
-    slowly and viscously spread back out to Earth's Roche limit, pushing along
-    outer bodies via resonant interactions. After several tens of years, the
-    disk spread beyond the Roche limit, and started producing new objects that
-    continued the growth of the Moon, until the inner disk was depleted in mass
-    after several hundreds of years.
     |]
+    "",
+
+    CalendarEntry (2.6 & millionYearsAgo) Nothing
+    "First Stone Tools"
     [text|
-    https://en.wikipedia.org/wiki/Giant-impact_hypothesis#Basic_model
-    https://www.psi.edu/epo/moon/moon.html
-    |],
+    Mode I: The Oldowan Industry
+    Stone flakes with sharp edges for cutting
+    |]
+    [text|
+    The earliest known Oldowan tools yet found date from 2.6 million years ago,
+    during the Lower Palaeolithic period, and have been uncovered at Gona in
+    Ethiopia.[16] After this date, the Oldowan Industry subsequently spread
+    throughout much of Africa, although archaeologists are currently unsure
+    which Hominan species first developed them, with some speculating that it
+    was Australopithecus garhi, and others believing that it was in fact Homo
+    habilis.[17]
 
-    CalendarEntry (600 & millionYearsAgo) Nothing
-    "Multicellular life"
-    ""
+    Homo habilis was the hominin who used the tools for most of the Oldowan in
+    Africa, but at about 1.9-1.8 million years ago Homo erectus inherited them.
+    The Industry flourished in southern and eastern Africa between 2.6 and 1.7
+    million years ago, but was also spread out of Africa and into Eurasia by
+    travelling bands of H. erectus, who took it as far east as Java by 1.8
+    million years ago and Northern China by 1.6 million years ago.
+    |]
+    "",
+
+    CalendarEntry (1.8 & millionYearsAgo) Nothing
+    "First major transition in stone tool technology"
+    [text|
+    Mode II: The Acheulean Industry
+    Stone hand-axes shaped symmetrically from two sides
+    |]
+    [text|
+    From the Konso Formation of Ethiopia, Acheulean hand-axes are dated to about
+    1.5 million years ago using radiometric dating of deposits containing
+    volcanic ashes.[6] Acheulean tools in South Asia have also been found to be
+    dated as far as 1.5 million years ago.[7] However, the earliest accepted
+    examples of the Acheulean currently known come from the West Turkana region
+    of Kenya and were first described by a French-led archaeology team.[8] These
+    particular Acheulean tools were recently dated through the method of
+    magnetostratigraphy to about 1.76 million years ago, making them the oldest
+    not only in Africa but the world.[9] The earliest user of Acheulean tools
+    was Homo ergaster, who first appeared about 1.8 million years ago. Not all
+    researchers use this formal name, and instead prefer to call these users
+    early Homo erectus.[3]
+    |]
+    "",
+
+    CalendarEntry (160 & thousandYearsAgo) Nothing
+    "Second major transition in stone tool technology"
+    [text|
+    Mode III: The Levallois technique; The Mousterian Industry
+    Stone scrapers, knives, and projectile points
+    |]
+    [text|
+    Levallois is a "prepared-core" technique: one face of a stone core is fully
+    shaped by knapping in perparation. Then a large sharp flake is created by
+    cracking off the entire prepared face in one final stroke.
+
+    The technique is first found in the Lower Palaeolithic but is most commonly
+    associated with the Neanderthal Mousterian industries of the Middle
+    Palaeolithic. In the Levant, the Levallois technique was also used by
+    anatomically modern humans during the Middle Stone Age. In North Africa, the
+    Levallois technique was used in the Middle Stone Age, most notably in the
+    Aterian industry to produce very small projectile points. While Levallois
+    cores do display some variability in their platforms, their flake production
+    surfaces show remarkable uniformity. As the Levallois technique is
+    counterintuitive, teaching the process is necessary and thus language is a
+    prerequisite for such technology.[2]
+
+    The Mousterian (or Mode III) is a techno-complex (archaeological industry)
+    of stone tools, associated primarily with the Neanderthals in Europe, and to
+    a lesser extent the earliest anatomically modern humans in North Africa and
+    West Asia. The Mousterian largely defines the latter part of the Middle
+    Paleolithic, the middle of the West Eurasian Old Stone Age. It lasted
+    roughly from 160,000 to 40,000 BP. If its predecessor, known as Levallois or
+    Levallois-Mousterian, is included, the range is extended to as early as c.
+    300,000–200,000 BP.[2] The main following period is the Aurignacian (c.
+    43,000–28,000 BP) of Homo sapiens.
+    |]
+    "",
+
+    CalendarEntry (115 & thousandYearsAgo) (Just $ 11.7 & thousandYearsAgo)
+    "The Ice Age begins"
+    "Glaciers cover most land on Earth, joining Asia to North America"
+    [text|
+    The Last Glacial Period (LGP), also known colloquially as the last ice age
+    or simply ice age,[1] occurred from the end of the Eemian to the end of the
+    Younger Dryas, encompassing the period c. 115,000 – c. 11,700 years ago. The
+    LGP is part of a larger sequence of glacial and interglacial periods known
+    as the Quaternary glaciation which started around 2,588,000 years ago and is
+    ongoing.[2] The definition of the Quaternary as beginning 2.58 million years
+    ago (Mya) is based on the formation of the Arctic ice cap. The Antarctic ice
+    sheet began to form earlier, at about 34 Mya, in the mid-Cenozoic
+    (Eocene–Oligocene extinction event). The term Late Cenozoic Ice Age is used
+    to include this early phase.[3]
+    |]
+    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
+
+    CalendarEntry (50 & thousandYearsAgo) Nothing
+    "Third major transition in stone tool technology"
+    [text|
+    Mode IV: The Aurignacian Industry
+    Long stone blades
+    |]
+    [text|
+    The widespread use of long blades (rather than flakes) of the Upper
+    Palaeolithic Mode 4 industries appeared during the Upper Palaeolithic
+    between 50,000 and 10,000 years ago, although blades were produced in small
+    quantities much earlier by Neanderthals.[20] The Aurignacian culture seems
+    to have been the first to rely largely on blades.[21] The use of blades
+    exponentially increases the efficiency of core usage compared to the
+    Levallois flake technique, which had a similar advantage over Acheulean
+    technology which was worked from cores.
+    |]
+    "https://en.wikipedia.org/wiki/Stone_tool#Mode_IV:_The_Aurignacian_Industry",
+
+    CalendarEntry (35 & thousandYearsAgo) Nothing
+    "Last major transition in stone tool technology"
+    [text|
+    Mode V: The Microlithic Industries
+    Stone blades fastened to wood or bone handles
+    |]
+    [text|
+    Mode 5 stone tools involve the production of microliths, which were
+    used in composite tools, mainly fastened to a shaft.[22] Examples include
+    the Magdalenian culture. Such a technology makes much more efficient use of
+    available materials like flint, although required greater skill in
+    manufacturing the small flakes. Mounting sharp flint edges in a wood or bone
+    handle is the key innovation in microliths, essentially because the handle
+    gives the user protection against the flint and also improves leverage of
+    the device.
+    |]
+    "https://en.wikipedia.org/wiki/Stone_tool#Mode_V:_The_Microlithic_Industries"
+    ,
+
+    CalendarEntry (12 & thousandYearsAgo) Nothing
+    "Agriculture leads to permanent settlements"
+    "Neolithic age (\"new stone age\")"
     [text|
+    Wild grains were collected and eaten from at least 105,000 years ago.[2]
+    However, domestication did not occur until much later. The earliest evidence
+    of small-scale cultivation of edible grasses is from around 21,000 BC with
+    the Ohalo II people on the shores of the Sea of Galilee.[3] By around 9500
+    BC, the eight Neolithic founder crops – emmer wheat, einkorn wheat, hulled
+    barley, peas, lentils, bitter vetch, chickpeas, and flax – were cultivated
+    in the Levant.[4] Rye may have been cultivated earlier, but this claim
+    remains controversial.[5] Rice was domesticated in China by 6200 BC[6] with
+    earliest known cultivation from 5700 BC, followed by mung, soy and azuki
+    beans. Rice was also independently domesticated in West Africa and
+    cultivated by 1000 BC.[7][8] Pigs were domesticated in Mesopotamia around
+    11,000 years ago, followed by sheep. Cattle were domesticated from the wild
+    aurochs in the areas of modern Turkey and India around 8500 BC. Camels were
+    domesticated late, perhaps around 3000 BC.
     |]
+    "https://en.wikipedia.org/wiki/History_of_agriculture",
+
+    CalendarEntry (6.5 & thousandYearsAgo) Nothing
+    "First copper tools"
     ""
-    ]
+    ""
+    "",
 
-  where
-    theYear = yearsAgo . toRational . (currentYear -)
-    yearsBeforeCommonEra = yearsAgo . toRational . ((+) (currentYear - 1))
-    earthDescription = [text|
-    The standard model for the formation of the Solar System (including the
-    Earth) is the solar nebula hypothesis.[23] In this model, the Solar System
-    formed from a large, rotating cloud of interstellar dust and gas called the
-    solar nebula. It was composed of hydrogen and helium created shortly after
-    the Big Bang 13.8 Ga (billion years ago) and heavier elements ejected by
-    supernovae. About 4.5 Ga, the nebula began a contraction that may have been
-    triggered by the shock wave from a nearby supernova.[24] A shock wave would
-    have also made the nebula rotate. As the cloud began to accelerate, its
-    angular momentum, gravity, and inertia flattened it into a protoplanetary
-    disk perpendicular to its axis of rotation. Small perturbations due to
-    collisions and the angular momentum of other large debris created the means
-    by which kilometer-sized protoplanets began to form, orbiting the nebular
-    center.[25]
+    CalendarEntry (5.3 & thousandYearsAgo) Nothing
+    "First bronze tools, first written language"
+    "The Bronze Age"
+    ""
+    "",
 
-    The center of the nebula, not having much angular momentum, collapsed
-    rapidly, the compression heating it until nuclear fusion of hydrogen into
-    helium began. After more contraction, a T Tauri star ignited and evolved
-    into the Sun. Meanwhile, in the outer part of the nebula gravity caused
-    matter to condense around density perturbations and dust particles, and the
-    rest of the protoplanetary disk began separating into rings. In a process
-    known as runaway accretion, successively larger fragments of dust and debris
-    clumped together to form planets.[25] Earth formed in this manner about 4.54
-    billion years ago (with an uncertainty of 1%)[26][27][4] and was largely
-    completed within 10–20 million years.[28] The solar wind of the newly formed
-    T Tauri star cleared out most of the material in the disk that had not
-    already condensed into larger bodies. The same process is expected to
-    produce accretion disks around virtually all newly forming stars in the
-    universe, some of which yield planets.[29]
+    CalendarEntry (3000 & yearsBeforeCommonEra) (Just $ 2350 & yearsBeforeCommonEra)
+    "Corded Ware culture"
+    "Indo-European languages spread across Europe and Asia"
+    [text|
+    The Corded Ware culture comprises a broad archaeological horizon of Europe
+    between ca. 3000 BCE – 2350 BCE, thus from the late Neolithic, through the
+    Copper Age, and ending in the early Bronze Age.[2] Corded Ware culture
+    encompassed a vast area, from the contact zone between the Yamnaya culture
+    and the Corded Ware culture in south Central Europe, to the Rhine on the
+    west and the Volga in the east, occupying parts of Northern Europe, Central
+    Europe and Eastern Europe.[2][3] The Corded Ware culture is thought to have
+    originated from the westward migration of Yamnaya-related people from the
+    steppe-forest zone into the territory of late Neolithic European cultures
+    such as the Globular Amphora and Funnelbeaker cultures,[4][5][6] and is
+    considered to be a likely vector for the spread of many of the Indo-European
+    languages in Europe and Asia.[1][7][8][9]
+
+    Corded Ware encompassed most of continental northern Europe from the Rhine
+    on the west to the Volga in the east, including most of modern-day Germany,
+    the Netherlands, Denmark, Poland, Lithuania, Latvia, Estonia, Belarus, Czech
+    Republic, Austria, Hungary, Slovakia, Switzerland, northwestern Romania,
+    northern Ukraine, and the European part of Russia, as well as coastal Norway
+    and the southern portions of Sweden and Finland.[2] In the Late
+    Eneolithic/Early Bronze Age, it encompassed the territory of nearly the
+    entire Balkan Peninsula, where Corded Ware mixed with other steppe
+    elements.[11]
+
+    Archaeologists note that Corded Ware was not a "unified culture," as Corded
+    Ware groups inhabiting a vast geographical area from the Rhine to Volga seem
+    to have regionally specific subsistence strategies and economies.[2]: 226 
+    There are differences in the material culture and in settlements and
+    society.[2] At the same time, they had several shared elements that are
+    characteristic of all Corded Ware groups, such as their burial practices,
+    pottery with "cord" decoration and unique stone-axes.[2]
     |]
-    recombinationDescription = [text|
-    At about 370,000 years,[3][4][5][6] neutral hydrogen atoms finish forming
-    ("recombination"), and as a result the universe also became transparent for
-    the first time. The newly formed atoms—mainly hydrogen and helium with
-    traces of lithium—quickly reach their lowest energy state (ground state) by
-    releasing photons ("photon decoupling"), and these photons can still be
-    detected today as the cosmic microwave background (CMB). This is the oldest
-    direct observation we currently have of the universe.
+    "",
+
+    CalendarEntry (2800 & yearsBeforeCommonEra) (Just $ 1800 & yearsBeforeCommonEra)
+    "Bell Beaker culture"
+    [text|
+    copper daggers, v-perforated buttons, stone wrist-guards
+    copper, bronze, and gold working
+    long-distance exchange networks, archery
+    social stratification and the emergence of regional elites
     |]
-    recombinationReferences = [text|
-    https://en.wikipedia.org/wiki/Chronology_of_the_universe#The_very_early_universe
+    [text|
+    The Bell Beaker culture (also described as the Bell Beaker complex or Bell
+    Beaker phenomenon) is an archaeological culture named after the
+    inverted-bell beaker drinking vessel used at the very beginning of the
+    European Bronze Age. Arising from around 2800 BC, it lasted in Britain until
+    as late as 1800 BC[1][2] but in continental Europe only until 2300 BC, when
+    it was succeeded by the Unetice culture. The culture was widely dispersed
+    throughout Western Europe, being present in many regions of Iberia and
+    stretching eastward to the Danubian plains, and northward to the islands of
+    Great Britain and Ireland, and was also present in the islands of Sicily and
+    Sardinia and some small coastal areas in north-western Africa. The Bell
+    Beaker phenomenon shows substantial regional variation, and a study[3] from
+    2018 found that it was associated with genetically diverse populations.
 
-    3. Tanabashi, M. 2018, p. 358, chpt. 21.4.1: "Big-Bang Cosmology" (Revised
-    September 2017) by Keith A. Olive and John A. Peacock.
+    In its mature phase, the Bell Beaker culture is understood as not only a
+    collection of characteristic artefact types, but a complex cultural
+    phenomenon involving metalwork in copper and gold, long-distance exchange
+    networks, archery, specific types of ornamentation, and (presumably) shared
+    ideological, cultural and religious ideas, as well as social stratification
+    and the emergence of regional elites.[6][7] A wide range of regional
+    diversity persists within the widespread late Beaker culture, particularly
+    in local burial styles (including incidences of cremation rather than
+    burial), housing styles, economic profile, and local ceramic wares
+    (Begleitkeramik). Nonetheless, according to Lemercier (2018) the mature
+    phase of the Beaker culture represents "the appearance of a kind of Bell
+    Beaker civilization of continental scale."[8]
 
-    4. Notes: Edward L. Wright's Javascript Cosmology Calculator (last modified
-    23 July 2018). With a default H 0 {\displaystyle H_{0}} H_{0} = 69.6 (based
-    on WMAP9+SPT+ACT+6dFGS+BOSS/DR11+H0/Riess) parameters, the calculated age of
-    the universe with a redshift of z = 1100 is in agreement with Olive and
-    Peacock (about 370,000 years).
+    Bell Beaker people took advantage of transport by sea and rivers, creating a
+    cultural spread extending from Ireland to the Carpathian Basin and south
+    along the Atlantic coast and along the Rhône valley to Portugal, North
+    Africa, and Sicily, even penetrating northern and central Italy.[50] Its
+    remains have been found in what is now Portugal, Spain, France (excluding
+    the central massif), Ireland and Great Britain, the Low Countries and
+    Germany between the Elbe and Rhine, with an extension along the upper Danube
+    into the Vienna Basin (Austria), Hungary and the Czech Republic, with
+    Mediterranean outposts on Sardinia and Sicily; there is less certain
+    evidence for direct penetration in the east.
+    |]
+    "https://en.wikipedia.org/wiki/Bell_Beaker_culture",
 
-    5. Hinshaw, Weiland & Hill 2009. See PDF: page 45, Table 7, Age at
-    decoupling, last column. Based on WMAP+BAO+SN parameters, the age of
-    decoupling occurred 376971+3162−3167 years after the Big Bang.
+    CalendarEntry (11.7 & thousandYearsAgo) Nothing
+    "Ice Age ends"
+    ""
+    ""
+    "https://en.wikipedia.org/wiki/Last_Glacial_Period",
 
-    6. Ryden 2006, pp. 194–195. "Without going into the details of the
-    non-equilibrium physics, let's content ourselves by saying, in round
-    numbers, zdec ≈ 1100, corresponding to a temperature Tdec ≈ 3000 K, when the
-    age of the universe was tdec ≈ 350,000 yr in the Benchmark Model. (...) The
-    relevant times of various events around the time of recombination are shown
-    in Table 9.1. (...) Note that all these times are approximate, and are
-    dependent on the cosmological model you choose. (I have chosen the Benchmark
-    Model in calculating these numbers.)"
+    CalendarEntry (1600 & yearsBeforeCommonEra) Nothing
+    "Dynastic China"
+    "History begins"
+    [text|
+    The earliest known written records of the history of China date from as
+    early as 1250 BC, from the Shang dynasty (c. 1600–1046 BC), during the king
+    Wu Ding's reign
 
-    https://en.wikipedia.org/wiki/Recombination_(cosmology)#cite_note-2
+    The state-sponsored Xia–Shang–Zhou Chronology Project dated them from c.
+    1600 to 1046 BC based on the carbon 14 dates of the Erligang site.
     |]
+    "",
+
+    CalendarEntry (480 & yearsBeforeCommonEra) Nothing
+    "Old Testament, Buddha"
+    ""
+    ""
+    "",
+
+    CalendarEntry (6 & yearsBeforeCommonEra) Nothing
+    "Christ born"
+    ""
+    ""
+    "",
+
+    -- CalendarEntry (300 & yearsBeforeCommonEra) Nothing
+    -- "Eratosthenes calculates the circumference of Earth"
+    -- ""
+    -- ""
+    -- "",
+
+    CalendarEntry (theYear 570) Nothing
+    "Muhammad born"
+    ""
+    ""
+    "",
+
+    CalendarEntry (theYear 1492) Nothing
+    "Columbus arrives in America"
+    ""
+    ""
+    ""
+  ]