Constant variables variable variables

2001/08/17 Astobiza, Amaia

• Fisika
• Astronomia

The constant of the fine structure is the constant that relates the speed of light, the charge of the electron and the constant of Planck. The combination of these three allows to obtain the value of the force of interaction between light and matter, for example, the force that binds the electron to the atom. In other words, this constant determines the organization of the universe. Currently it is assumed that the value of the constant is approximately 1/37. Being constant, it seems reasonable to think that the universe has had the same value since its creation. But the latest research indicates that it has not always been so.

This is the question that astronomers have had around the years: Have the values of constants been fixed at the beginning of the universe or have they been changing little by little? To answer this question, astronomer John Webb of the University of New South Wales in Sydney and collaborators of Australia, England and the United States have analyzed the wavelength of light emitted by quasars and the results obtained will be published in the journal Physical Review Letters of 27 August. The research was conducted with a powerful telescope at the Keck Observatory, located in Hawaii.

The quasars are the most distant objects we can see (up to 1010 light years) and present a clear glide in their spectrum towards the red. As they are so far away, the light they emit takes a long time to reach us. That is why we can see the universe as it was when it just created.

On the way to earth, the light emitted by the quasars crosses the interstellar gas. This gas is formed by magnesium, iron, nickel and other atoms that absorb radiation of certain wavelengths. Consequently, in the spectrum of quasars appear dark lines indicating this absorption. The fine structure constant allows to determine the relative positions of these lines, since the absorption of light depends on the interaction between the electron and the atom.

Analyzing the light absorption lines of the 72 quasars, it seems that thousands of millions of years ago the value of the fine structure constant was 0.001% lower than the current one. If this conclusion is correct, some basic convictions of physics would be suspended.

However, many scientists do not agree with the results obtained. Lennox Cowie, of the Institute of Astronomy of Hawaii, for example, considers that the composition of the clouds that absorb light is variable, so it is normal that changes occur in the lines of the spectrum. However, researchers say they have taken this effect into account. However, they believe that another group of researchers should repeat the observation to confirm the results obtained and also convince the most skeptical.

Meanwhile, we are waiting for these new results to decide whether or not to change the constants we have saved in the calculator's memory.

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