CONSTANT CONSTANTS? SHEDDING LIGHT ON THE ANSWER

CONSTANT CONSTANTS? SHEDDING LIGHT ON THE ANSWER

Scientists are delvinga as far into the past as possible to establish whether the constants of nautre have changed at any time during the existence of the universe. For this they are analysing the light from the quasars.

Lightwaves from the quasars began their journey shortly afther evolution of the cosmos and have now reached the earth. while they were on their way, the universe expanded and in the process their wavelengths stretched and their colour shifted towards the red end of the spectrum. The extent of this 'redshift' indicates the time taken for the light to travel. On its journey, whenever the light passed through gas clouds, atoms in these clouds absorbed specific wavelengths of the light. this meant that electrons were catapulted to a higher orbit, the position of which depends on the fine structure constant alpha. If alpha had a different value earlier, other wavelenths would have been absorbed than those present in gas clouds today.

Such clouds are simulated in the laboratory in order to compare the light that passes through them with the light from the cosmic objects. Since absorption by atoms imprints a kind of barcode on the light, the comparison of 'old' barcodes with 'new' ones should establish whether the fundamental constant alpha has changed or not