Monthly Archives: September 2013

Subject-Verb-Object

Sentences have three main parts: the subject of the sentence, the object of the sentence, and a verb that links the two together.

In English, sentences follow the SVO (subject-verb-object) order, for example in the sentence “She loves him”, “She” is the subject, “loves” is the verb and “him” is the object. Other languages that follow the SVO order include Chinese, French and Russian, but SVO is not the most common arrangement.

The most common arrangement is SOV (subject-object-verb), which is found in 45% of languages (as opposed to the 42% of languages which use SVO) and in this case, our example sentence becomes “She him loves”. This arrangement is found in Japanese, Korean and Pashto.

The remaining 13% of languages use the other four possible arrangements:

  • VSO (“Loves she him”) is found in 9% of languages, including Arabic, Hebrew and Gaelic. (i.e. it is found in the semitic and celtic languages.
  • VOS (“Loves him she”) is found in 3% of languages, including Malagasy, Tagalog and Fijian.
  • OVS (“Him loves she”) and OSV (“Him she loves”) make up the remaining 1% of languages, with OSV being present in only one known case: Warao, spoken by around 28 000 people in Venezuela, Guyana and Suriname.

Just because a sentence doesn’t follow the SOV arrangement doesn’t mean that it won’t be understandable to English speakers. One of the most famous sentences in the English language “With this ring, I thee wed.” follows the SOV arrangement.

Where did all the elements come from?

Matter is made up of atoms, and each atom is one of (currently) 118 elements. But where did those elements come from?

Note: Each element has a different atomic number (represented by the symbol Z (from the German Zahl for number) which represents the number of protons in the element’s nucleus.

Hydrogen, Helium and Lithium (Z=1 to Z=3)

Hydrogen, helium and lithium were formed in the Big Bang, by a process called Big Bang nucleosynthesis. Unstable radioactive isotopes of beryllium were also formed, but those would quickly decay into other elements or fuse with other stable atoms.

Big Bang nucleosynthesis occurred from about one-tenth of a second to one thousand seconds after the Big Bang and involved the creation of protons and neutrons from the quark-gluon plasma that existed before it, and then the creation of hydrogen, helium and lithium from these protons and neutrons.

Beryllium to Iron (Z=4 to Z=26)

A process called stellar nucleosynthesis, where lighter elements are fused into heavier ones with the release of energy (i.e. an exothermic fusion reaction) is responsible for the creation of the elements from beryllium to nickel. Some nickel-56 and zinc-60 is also produced, but these are unstable and decay quickly to form iron-56 and copper-60. It is the decay of nickel-56 into iron-56 which is responsible for the high amount of iron-56 found in meteorites and planetary cores. (For example, both the Earth’s solid inner core and liquid outer core are composed primarily of an iron-nickel alloy.)

There are a variety of stellar nucleosynthesis processes responsible for the formation of these elements: the alpha and triple-alpha processes and the “burning” of lithium, carbon, neon, oxygen and silicon formed in earlier stages. Stellar nucleosynthesis is also responsible for the creation of more helium via the “burning” of deuterium, the proton-proton chain, and the carbon-nitrogen-oxygen cycle.

Cobalt to Californium (Z=27 to Z=98)

There are three processes responsible for the creation of elements heavier than iron: the S-process, the R-process and the Rp-process (sometimes called the P-process). The S-process (slow neutron capture) occurs in low- to medium-mass stars and is when neutrons emitted by fusion reactions between lighter elements are absorbed by heavy nuclei like iron; this process forms about half of the elements heavier than iron.

The R-process (rapid neutron capture) probably occurs in the core of core-collapse supernovae when electrons are forced back “inside” protons to produce an extremely high flux of neutrons which are rapidly absorbed (hence the name) by heavy nuclei like iron. The R-process forms about half of the elements heavier than iron, and most if not all of the heaviest elements like uranium.

A minority of the heavier elements are formed by the Rp-process (rapid proton capture), and these are all lighter elements (evidence suggests it cannot form elements heavier than tellurium (Z=52). It occurs in very high-temperature hydrogen-rich environments like the outer layers of a star undergoing a core-collapse supernova.

Trace amounts of heavier-than-iron elements with atomic numbers 92 to 99 were, and are, also produced naturally on Earth by radioactive decay processes.

Einsteinium to Ununoctium (Z=99 to Z=118)

Small amounts of the lightest of these elements may be produced as outlined above by the S-, R- and Rp-processes, but the majority of them have only ever been produced artificially, in laboratories, by humans. They are all extremely radioactive and have very short half-lives so only exist for tiny fractions of a second when they are created (e.g. element 118, ununoctium has a half life of about 0.9 milliseconds).

The processes by which these heaviest of the elements are created vary. Einsteinium was first detected as a by-product of the first fusion bomb (H-bomb) test, fermium is formed by bombarding lighter lanthanides with neutrons, and mendelevium by the bombardment of californium by alpha particles. The remaining elements have all been created by smashing together two larger nuclei: for example, ununoctium was first produced by colliding krypton-86 and lead-208.

Tons and Tonnes

Every time I see the word “ton” or “tonne” used to describe mass or weight I have to go back and check exactly what the terms mean, so for my sanity and your reference, here is an explanation of the differences.

ton-tonne-comparison

The long ton is an outdated unit, equivalent to 1016 kilograms, still sometimes used in the UK and in other countries that previously used the Imperial system of measurements.

The short ton is one of the US customary units, equivalent to 907 kilograms. For certain types of measurements (e.g. the tonnage of Navy ships) the long ton is used instead.

The tonne is 1000 kilograms, and is part of the International System of Units, which is why it it often referred to as a metric tonne.

A long ton is 12% larger than a short ton, and 1.6% larger than a tonne. A short ton is 9.3% smaller than a tonne and 11% smaller than a long ton. A tonne is 1.6% smaller than a long ton and 10% larger than a short ton. And if you read that out loud you’ll realise how dangerous using the ton/tonne can be.