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It seems like the universe is always serving up some mysterious new form of energy for scientists to ponder. In the late ’90s, for example, two teams discovered dark energy — a mysterious force that’s making the universe expand faster as it ages. The discovery won the teams this year’s Nobel Prize for physics.
Decades earlier, it was another mysterious form of energy, known today as cosmic rays. That discovery also merited a Nobel, which went to Victor Hess 75 years ago this month.
Scientists had found that air inside special experimental chambers always became electrically charged, no matter how the chambers were sealed. They first thought the charge was caused by radioactive elements in Earth’s crust. But raising the chambers to greater heights only increased the effect.
To Hess, that meant the charge must come from above the ground. So he built better instruments than anyone else was using, then carried them up in balloons. Starting in 1911 he made a total of 10 flights, at altitudes of up to three miles. The higher he went, the stronger the radiation. He concluded that the source was beyond Earth. Another scientist later called this radiation “cosmic rays.”
It took decades more for scientists to figure out much about cosmic rays, though. They’re electrically charged particles — some from the Sun and other stars, and some from outside the Milky Way galaxy. But the exact source of the powerful cosmic rays from outside the galaxy remains a mystery.
Script by Damond Benningfield, Copyright 2011
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