Download Generalization of the concept

Is cosmic radiation dangerous?
Observation
The main exhibition in Heureka features a stand where you can observe traces left by cosmic
radiation in a fog chamber. There is a constant sparkling of rays,
which leave impressive traces in the liquid that is in the chamber.
Since man is also mostly made of water, a frightful question
inevitably comes to mind: Is cosmic radiation dangerous?
Video clip presenting the Cosmic radiation display in Heureka:
http://www.youtube.com/watch?v=1UJKz6wSXgcExploration
Exploration
Cosmic radiation cannot be perceived by human senses. It can’t be felt, heard or seen, nor does it
have any smell or taste. It can only be observed indirectly, when reacting to the liquid in the fog
chamber – or up on the sky, as aurora borealis. Thus in exploring cosmic radiation it is best to rely
principally on materials available in books and online.
However, some calculations about the degree of harmfulness of cosmic radiation can be made:
http://en.wikipedia.org/wiki/Radiation_poisoning
Concept introduction
The human brain has about 100 milliard nerve cells, neurons. Their destruction would without doubt
have a fateful effect on a human being, as they are unrenewable cells. Most of the cosmic radiation
that enters the human head goes straight through it without interacting in any way with the cells.
This part of the radiation is, of course, completely harmless.
In the device on display in Heureka, it seems that radiation and matter interact about once a second.
Since the device is about the same size as a human brain, one can assume that cosmic radiation
affects the brain cells approximately once a second. If we assume that radiation destroys one brain
cell a second, a human being living up to 100 years would have 60*60*24*365*100 = circa 3 milliard
cells destroyed. That would be 3% of a human being’s brain capacity, which probably would already
make its effect felt.
Fortunately there is a slight error in the calculation here, to the advantage of the brain. The human
brain has approximately a milliard milliard, i. e. a billion support cells apart from the brain cells. As
the radiation does not choose its target according to the importance of the cell to the human brain,
one can assume that it affects only about 0.3% of a human being’s brain cells during a person’s life
span. What is more, not nearly every interaction causes a cell to be destroyed, so on the basis of this
calculation it’s safe to assume that cosmic radiation is not very dangerous to man.
Another point of view to the matter would be comparing the amount of cosmic radiation to all other
radiation. The amount of natural radiation in Finland is approximately 3.7 mSv a year. The amount
varies quite significantly from area to area, as the most important single factor is radon, the amount
of which is largely dependant on the soil. The amount of cosmic radiation is 0.3 mSv a year and it
cannot be protected from. However, this amount is so small that the risk of it causing cancer, for
example, is negligible in comparison with other factors.
http://en.wikipedia.org/wiki/Ionizing_radiation
Generalization of the concept
Most, though not all, of cosmic radiation comes from the sun. The word “radiation” is somewhat
misleading, as we are really dealing with particles. 99% of the radiation consists of alpha particles
and 1% of beta particles. Both of them have an electric charge, a property that is essential for
organisms on Earth. The charged particles are affected by the Earth’s magnetic field, which prevents
most of the particles from entering Earth. Some of them it turns away altogether, while others are
directed towards the poles of the Earth, where they become visible as auroras. Without the Earth’s
magnetic field cosmic radiation would be fatal to the organisms. When admiring the auroras that are
visible from time to time on the Northern sky, one can derive additional pleasure from the fact that
a large part of the lethal power of cosmic radiation is ”wasted” on exciting oxygen and hydrogen
molecules just before it arrives on Earth. It is the eruption of these excited states that we perceive as
the auroras' light, which for its part is completely harmless.
http://en.wikipedia.org/wiki/Aurora_(astronomy)
For cosmology, cosmic background radiation constitutes one of the most important observations.
Thanks to it, scientists have been able to deduce a lot about the birth of the Universe.
http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation