Helium-4

Helium-4 (4
2He or 4He) is a non-radioactive isotope of the element helium. It is by far the most abundant of the two naturally occurring isotopes of helium, making up about 99.99986% of the helium on Earth. Its nucleus is identical to an alpha particle, and consists of two protons and two neutrons.

Alpha decay of heavy elements in the Earth's crust is the source of most naturally occurring helium-4 on Earth. While it is also produced by nuclear fusion in stars, most helium-4 in the Sun and in the universe is thought to have been produced by the Big Bang, and is referred to as "primordial helium". However, primordial helium-4 is largely absent from the Earth, having escaped during the high-temperature phase of Earth's formation. Radioactive decay from other elements is the source of most of the helium-4 found on Earth, produced after the planet cooled and solidified.

Helium-4 makes up about one quarter of the ordinary matter in the universe by mass, with almost all of the rest being hydrogen.

Helium

Helium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table. Its boiling and melting points are the lowest among all the elements.

Helium is the second lightest element and is the second most abundant element in the observable universe, being present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this figure in the Sun and in Jupiter. This is due to the very high nuclear binding energy (per nucleon) of helium-4 with respect to the next three elements after helium. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. Most helium in the universe is helium-4, and is believed to have been formed during the Big Bang. Large amounts of new helium are being created by nuclear fusion of hydrogen in stars.

Helium is named for the Greek god of the Sun, Helios. It was first detected as an unknown yellow spectral line signature in sunlight during a solar eclipse in 1868 by French astronomer Jules Janssen. Janssen is jointly credited with detecting the element along with Norman Lockyer. Jannsen observed during the solar eclipse of 1868 while Lockyer observed from Britain. Lockyer was the first to propose that the line was due to a new element, which he named. The formal discovery of the element was made in 1895 by two Swedish chemists, Per Teodor Cleve and Nils Abraham Langlet, who found helium emanating from the uranium ore cleveite. In 1903, large reserves of helium were found in natural gas fields in parts of the United States, which is by far the largest supplier of the gas today.

Helium (film)

Helium is an Oscar-winning 2014 short film by Danish film maker Anders Walter.

Plot

Alfred is a young boy staying in a hospital who suffers from an undisclosed terminal illness. Enzo, a janitor at the hospital, meets Alfred while working and the two develop a friendship. Enzo tells Alfred of Helium, an attractive alternative to Heaven, because Alfred imagines Heaven is very boring. Enzo tells Alfred that to get to Helium, he will fly in an airship that will know to pick him up because of his red balloon dog, which Enzo has made for him.

Alfred's illness worsens, and he is moved to a unit to which Enzo doesn’t have access. Enzo sneaks onto the unit, but is caught by the head nurse and barred from seeing Alfred. As Alfred's condition worsens, Enzo wonders if he is making it worse for the boy. He voices these concerns to a nurse saying, “I’m feeding him lies.” She disagrees and tells Enzo “you’re giving him hope.”

Alfred gets worse, and having no access to him, Enzo writes out “the end of the story” to have the nurse read to him. As the nurse is about to read the ending to a dying Alfred, she changes her mind and, instead, sneaks Enzo onto the unit to tell the rest himself.

Helium (Haskell)

Helium is a compiler and a dialect of the functional programming language Haskell. It has been designed to make learning Haskell easier by giving clearer error messages. It is being developed at Utrecht University, Netherlands, primarily by Arjan van IJzendoorn, Daan Leijen, Bastiaan Heeren and Rijk-Jan van Haaften.

Certain language features of Haskell have not been included to create more specific error messages. For this reason, it (currently) lacks type classes, rendering it incompatible with many Haskell programs.

It also includes Hint, an interpreter written in Java with a graphical user interface.

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