Neutrino
A type of particle which has no charge and an extremely small mass. It is a Fermion, and is extremely difficult to stop or to detect. Nonetheless, they are produced in large numbers. The Sun, for example, sends 30 million neutrinos through every square inch of the Earth every single second. They are so hard to stop, however, that if a neutrino were sent through a solid light year of lead, it would still have a 50:50 chance of flying right through without stopping.
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Four Areas of Science
Inspiration
Go, wond'rous creature!
Mount where Science guides,
Go, measure earth, weigh air,
and state the tides;
Instruct the planets in
what orbs to run,
Correct old Time,
and regulate the Sun.