Blogs de Ciência

Text in English (PARA O TEXTO EM PORTUGUES, LEIA MAIS ABAIXO)

Literally speaking, the atoms present in the galaxies spread out all over the universe talk to us using their own language: Like our vocal apparatus or any musical instrument such as violins containing strings and resonant cavities for sound waves, the atoms work as (spherical or other shapes) resonant cavities holding standing material waves. The equivalence to the standing waves in vibrating strings, as in violins, is played by material deBroglie electron standing waves. As the timbre of any musical instrument, each of the ninety two stable elements has a multiplicity of typical tunes. Similarly, like the bow exciting the violin strings to produce typical sounds, thermal excitations promote electronic transitions to emit specific spectra of frequencies of (not sound but) electromagnetic radiation, in a large range such as infra-red, light, X-rays, etc.

We give two examples to enlighten why each of the ninety two elements has its own radiance spectrum, or signature:

Hydrogen has a spherical potential (or resonant cavity) centered in the nucleus which is composed by a single proton. Using quantum mechanics tools it is aesthetically easy to understand that such a symmetric “box” fits electron-standing-waves of specific wavelengths associated to specific energies. Figure 1 shows two waves around the nucleus; the first one is a standing wave with exactly 4.0 wavelengths; the second contains a non integer number (7.3) of wavelengths. The first configuration fits the “resonant cavity” and corresponds to a specific harmonic to the hydrogen atom. The second does not, so it does no subsist! On the other hand, if it was 7.0 or 8.0, it would match another specific harmonic to fit the “cavity” and would be a potential resonant condition. When thermally excited, hydrogen emits light in many distinct frequencies consequent from electron transitions between existing harmonic states. The three most intense emissions are in the light frequencies of 457, 617 and 691 THz producing the red, blue and purple components of hydrogen emission spectrum (or signature).

Helium, the second element in the periodical table, has a nucleus containing two protons and two neutrons. This corresponds to a distinct “resonant cavity” for electron-waves, when compared with hydrogen, and the characteristic emission spectrum has the three most intense frequencies are 424, 449 and 598 THz (dark red, yellow and light green), a signature completely different from that of hydrogen.

Text in English (para o texto em Portugues, leia abaixo)

The year 2009 has been declared by the UN General Assembly the “International Year of Astronomy”. Four hundred years ago, in 1609, Johannes Kepler published “Astronomia Nova” containing two of his three famous laws (the firs Law regarding the elyptical planetary orbits and the second, the “Areas Law”). In the same year -1609- Galileo Galilei pointed for the first time his refractor telescope out to the sky. The findings of Kepler and Galileo, four hundred years ago changed radically the history and position of humanity in the Universe, influencing Isaac Newton to propose 60 years latter the “Universal Law of Gravitation”

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Em 2009 a humanidade comemorará 400 anos da publicação da “Astronomia Nova“, a obra de Johannes Kepler que, divulgando duas de suas três famosas leis (a primeira, sobre as órbitas planetárias elípticas e a segunda, conhecida como a lei das áreas) mudou radicalmente a nossa posição e história no Universo. O ano de 1609 foi também importante para a astonomia pois celebraremos o quarto-centenário das primeiras observações astronômicas por Galileu Galilei, que apontou sua luneta para o céu.  Por estas fortes razões, o ano de 2009 foi declarado pela ONU o “Ano Internacional da Astronomia“. Ambas as descobertas impulsionaram de modo definitivo a Física Clássica ao levar Isaac Newton a propor a Lei de Gravitação Universal, apenas seis décadas depois.