Infrared Spectroscopy


Cosmology is the study of the origin and evolution of the Universe. It is a field of astronomy that deals with questions like: How old is the Universe? How did it begin? Will it continue expanding or slow down and collapse? How did the chemical elements which make up our Universe form? Infrared spectroscopy offers clues which may lead to answers for many of these questions.

If the Universe did begin as a hot "Big Bang", there should still be a general background of radiation, now at an extremely low temperature, which is the remnant heat from the Big Bang itself. This radiation, called the cosmic background radiation, was originally detected by radio astronomers in the 1960's. In 1993, data from a far-infrared spectrometer aboard NASA's COBE was used to make the most accurate measure yet of this background radiation and showed that it is extremely close to that of a perfect blackbody at 2.726 K.

The plot to the right is a comparison of the predicted energy spectrum for the cosmic background radiation (from the Big Bang theory) compared with the actual data taken with COBE's infrared spectrometers. The error bars are so small that the two curves match up almost exactly - appearing as one curve in this plot. This result was an important test of the accuracy of the Big Bang theory.

ISO measures deuterium in Orion and confirms that the normal matter in the universe is not enough to cause the "Big Crunch".
One key to determining whether the Universe will continue expanding or eventually slow down and start collapsing is the amount of deuterium present in the Universe. Deuterium (sometimes called "heavy hydrogen") is a hydrogen atom which has both a proton and a neutron in its nucleus instead of just a proton as in the hydrogen atom. Most of the deuterium in the Universe is thought to have been created by the Big Bang itself. Since deuterium is directly related to the total amount of matter in the Universe, its accurate measure is an important way to determine whether the Universe will continue expanding or eventually collapse under it's own weight. Infrared spectral studies using data from the ISO satellite have shown that there is not enough deuterium present in space to indicate that the Universe will eventually collapse.

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