Beh, in effetti Marcopie non parlava di effetti biologici, francamente sarebbe interessante approfondire il discorso sui raggi cosmici che a quanto pare influenzano il nostro mondo più di quanto normalmenente si pensi (parlo per me).
Leggevo che i raggi cosmici interagendo nell'alta atmosfera con il nitrogeno forma il C14 un isotopo di cui troviamo traccia nel legno, tanto che il metodo è usato per rilevare le tracce della passata attività solare:
"Recent studies have demonstrated that the production of radiocarbon (14C) also is related to solar activity.
Radiocarbon is produced in the upper atmosphere by bombardment of atmospheric nitrogen (14N) with neutrons from outer space (cosmic rays).
An increase in solar activity (more sunspots) is accompanied by an increase in the “solar wind,” which is an outflow of ionized particles, mostly protons and electrons, from the sun. The solar wind reflects cosmic rays and reduces 14C production.
Therefore, the 14C concentration of the atmosphere is lower during sunspot maxima and higher during sunspot minima.
The 14C concentration of the atmosphere is recorded in the wood of trees.
By measuring the 14C content of wood from trees that are precisely dated by counting the annual tree rings, a relation between 14C and age can be constructed, and commonly is expressed as ∆14C (for example, Stuiver and Pearson, 1986; fig. 2A), where ∆14C is the radiocarbon activity
of the wood relative to mid-19th century wood. Such a reconstruction has been done for the last 11,000 years based on bi-decadal and decadal wood samples (for example, Damon and Sonnett, 1991).
This reconstruction shows that 14C production was much greater during the mid-Holocene
(approximately 7,000 years ago), and steadily decreased until about 1,000 years ago.
When this long-term secular variation trend in ∆14C is removed, the residual values show distinct cycles with periods of about 2,000 years (Hallstadtzeit Cycle; fig. 2B). "
Home
Iscriviti
La Bacheca
F.A.Q.
Login/Logout
