Slightly noisy
Using the Cobe satellite, the two American astrophysicists John Mather and George Smoot unraveled universal properties of the universe in the truest sense.
In the past, when the television stations stopped operating at night and didn't broadcast the umpteenth repetition of the most popular programs around the clock, as they do today, you could let yourself be gently lulled to sleep by the steady noise of the picture tube. What many people don't know: the birth cry of the universe is hidden in the trickling snow on the screen: part of the noise comes from the depths of space and rains down on us quite uniformly from all directions. This phenomenon was discovered by the two US physicists Arno Penzias and Robert Woodrow Wilson when they wanted to build a perfect antenna in 1964. But they just couldn't get rid of the last damn whisper, no matter what they did.
They found out why this is so some time later when they heard about the so-called Big Bang theory at a conference. According to this, our universe is said to have emerged from a massive explosion a good 14 billion years ago. A well-known representative of this idea was the Russian-born physicist George Gamow. Since then, according to his ideas, the universe has been expanding and cooling down.
According to the astrophysicists, the first particles, such as electrons, as well as protons, gradually formed in the then extremely hot primordial soup. Because of the high temperatures, however, they could not combine to form stable hydrogen atoms. It was not until a good 400,000 years after the Big Bang that the universe, with a temperature of around 3000 Kelvin, was "cold" enough to give in to the tendencies of the oppositely charged particles. They combined to form neutral atoms. At the same time, the universe became transparent. It's similar to the sun. With its average temperature of 6000 Kelvin, it also prevents the formation of hydrogen atoms. Light that hits our central star becomes a plaything for the protons and electrons whizzing around freely in this glowing ball and is therefore swallowed up mercilessly. That's why you can't see through the sun.
A good 400 millennia after the Big Bang ignited, photons – the particles of light and other electromagnetic radiation – were finally able to shake off the chains of matter and have been flying around freely ever since. According to calculations by Gamow, the reverberations of this act of liberation are still noticeable today - as an average temperature prevailing everywhere. It must have dropped to about minus 270 degrees Celsius by now and is causing this uniform noise that drove Penzias and Wilson almost to despair. The disappointment gave way to euphoria at the latest in 1978, when the two antenna builders were awarded the Nobel Prize in Physics for their work.
Now again two Americans have been honored with the highest scientific award. The two US astrophysicists John C. Mather from Nasa Goddard Space FlightCenter and George F. Smoot from the University of California in Berkeley were able to prove that this primal scream of the universe, now known among experts as cosmic background radiation, almost perfectly resembles a so-called black body and – which is perhaps even more important – that it has the smallest irregularities. They got their data from the Cobe mission, to the success of which they made a significant contribution. Cobe is short for the Cosmic Background Explorer satellite, which was launched into orbit around the Earth on November 18, 1989. He measured the properties of the background radiation with a previously unknown precision.
Black body radiators and …
Nasa expert Mather coordinated the entire project. At the same time, he was responsible for an experiment that was intended to show whether the residual radiation in the universe resembles that of a black body. Physicists understand this to mean a body that is characterized by a characteristic emission of energy, whose electromagnetic spectrum is independent of the material and depends only on its temperature. This finding goes back to the German physicist Max Planck and dates the beginning of modern quantum physics. However, the name was chosen somewhat unhappily: it emphasizes another property of physical objects, also known as "black bodies", with which they completely absorb any incident radiation. A glowing hot plate or our sun are examples of this - and the universe, which Cobe was able to determine just nine minutes after starting his observation.
… universal inequalities
Smoot, on the other hand, was recognized by the Nobel Prize Committee for the insights gained from the data from the detection devices on the Cobe satellite. They showed that the temperature in the universe is not the same everywhere, but differs locally - even if in some cases only by a few hundred-thousandths of a degree. According to the astrophysicists, the somewhat colder spots are due to so-called (quantum) fluctuations in the primordial soup and formed the germ cells for today's galaxies, for example. In addition, the scientists can use the distribution of the temperature differences to deduce the proportion of dark matter in the universe. According to current theory, most of the matter is invisible to our eyes - hence the name. Only about four percent of the gravity in space can be traced back to the existence of galaxies and the stars and accumulations of dust they contain. What the rest is made of is one of humanity's great unanswered mysteries.
In addition, the data obtained with Cobe can be used to determine whether our universe is flat as a sheet of paper, or whether the existing mass is sufficient to cover the universe - in accordance with the ideas of Albert Einstein's general theory of relativity bend so that it is self-contained. This question cannot yet be decided with absolute certainty by the experimenters. However, the results obtained with Cobe and its successor - the Wilkinson Microwave Anisotropy Probe WMAP - point to a flat, Euclidean space. In one of these, two parallel rays of light never cross, even at great distances, and disappear side by side, never to be seen again, in the endless expanses.
