Helium

Helium

Colorless noble gas. It is the second most abundant element (after hydrogen) in the universe. It was isolated by the Englishman William Ramsay in 1895 and named after the  Greek god of the sun, helios, because of the presence of helium in the sunlight spectrum. It does not combine with other elements, except  in unstable compounds with tungsten, iodine, fluorine, sulfur and phosphorus.

At temperatures below –270.97 °C, i.e. near the lowest possible temperature, it forms a special liquid called a “superfluid” that goes up or down along the edges of a container with velocities of up to 30 cm/s. In such a fluid, heat propagates in waves, as if it were sound, and these waves continue to move for some  distance after removing the heat source. Such a transport of heat is  called the “second sound” [1] and also occurs in solid helium [2].

If someone speaks in a helium atmosphere, the voice sounds like that of Donald Duck. In fact, this effect was used in the first cartoons, and occurs because helium is lighter than air, which results in a faster vibration, i.e. a higher frequency [3]. In the gas supply for a diver’s breath, nitrogen from the air is replaced by helium, since nitrogen dissolves in the blood at low pressure forming dangerous bubbles.

Helium airships, carrying video equipment, have several applications: detecting illegal immigration in coastal regions, studying the biology of treetops in the jungle, and – at much greater heights – studying ozone depletion. It is assumed that the occurance of ice ages had to do with instabilities of helium in the sun, implying changes in solar radiation [4].

[1] C.T. Laue et al., Phys. Rev. 1947, 71, 600–605. DOI: 10.1103/PhysRev.71.600

[2] B. Bertman and D.J. Sandifor, Scientific American 1970, 222(5), 92–101. DOI: 10.1038/scientificamerican0570-92

[3] C. Montgomery, Scientific American 2004, 291(3), 102–122. DOI: 10.1038/scientificamerican0904-102

[4] E. Bard and M. Frank, Earth and Planetray Science Letters 2006,
248, 1–14. DOI: 10.1016/j.epsl.2006.06.016

The noble clown
has no one to play with.
But in his circus,
playing with his audience,
he is never
lonely.

No one tempts
and no one burns him.
And yet: the show on his stage,
the garden
at the world’s edge,
keeps him away
from loneliness.
The actor Helium
crawls up and down
the walls of his stage.
A touch of heat
passes through his body
turns into sound
and keeps on flowing,
recalling the warmth
that’s there no more.

Let us play with helium.
Let us scream
with the voices
of birds.
Let him take us
to the crowns
of trees
and skies,
to hot or icy
ages
of the Earth.