VLT (Very Large Telescope) - an array of four telescopes placed on one of the peaks of the Andes mountains in Chile and together constitute the largest telescope in the world. With its help, researchers were able to measure the temperature of cosmic radiation more than 10 billion years ago
By: Avishai Gal-Yam
According to the theory currently accepted by the vast majority of cosmologists, the beginning of the universe was a massive cosmic explosion known as the "Big Bang". Immediately after its creation, the dimensions of the universe were infinitely small, and all existing matter was kept under conditions of enormous density and extremely high heat. From the Big Bang to the present day, the universe continues to expand, while the temperature and density of matter steadily decrease.
The Big Bang theory was developed in the middle of the 1929th century by a group of researchers led by the Russian-American cosmologist George Gamov, and it explains many fundamental observations in astronomy - first and foremost the fact that the universe is expanding, a discovery by the great American astronomer Edwin Hubble in 1964. Gamov and his colleagues predicted, among other things, that if a "big bang" did occur, it should have left behind a remnant in the form of cosmic electromagnetic radiation, the intensity of which should be approximately uniform everywhere in the universe. However, only about twenty years later, in XNUMX, the cosmic background radiation was discovered by chance by two researchers from Bell Laboratories in the United States, Arno Panzias and Robert Wilson.
If the origin of the cosmic background radiation is indeed in the big bang, the theory predicts that this radiation was extremely energetic shortly after the big bang and that it gradually fades away as the universe expands. One of the ways in which it is possible to characterize the properties of the background radiation is through its temperature. Hot bodies emit radiation whose properties depend on their temperature. Bleached iron, for example, emits a white-yellow light when it is very hot. As the iron cools, the light emitted from it becomes redder. Since, according to the theory, the background radiation was very energetic after the big bang and is fading away, it is commonly thought that the temperature of the background radiation was very high immediately after the big bang and that it has been decreasing ever since. Very precise measurements made by the COBE satellite, launched by NASA in 1989, determined that the temperature of the background radiation today is approximately minus 270 degrees Celsius, or 2.73 degrees above absolute zero.
The properties of the cosmic background radiation, as measured in recent years, correspond to the prediction of the Big Bang theory. However, the Big Bang theory also predicts that this radiation was hotter in the past. Can we check this? Apparently, this is an absurd idea, because in order to measure the background radiation temperature in the past, you have to go back in time. However, in the article published today in the journal "Nature", a group of researchers led by the astronomer R. Sriyanand from the University of Pune in India presents a measurement of the temperature of the background radiation in the past, which they performed without going on a time trip.
The scientists made use of a state-of-the-art detector that was installed not long ago in the largest telescope in the world today, known as the VLT (Very Large Telescope). VLT is an array of four large telescopes (the diameter of the main mirror in each of the units is about 8 meters), placed on one of the peaks of the Andes mountains in Chile and operated by the European Observatory, ESO. The quality and power of the VLT allowed researchers to measure with unprecedented precision the characteristics of the light reaching us from a distant cloud of cold gas. This cloud is at such a great distance from the Earth that the light emitted from it takes more than ten billion years to reach it. This means that the observations we make today reflect the conditions in the gas cloud as they were more than ten billion years ago.
The astronomers measured with great precision the light emitted by atoms and molecules of various types found in the distant gas cloud, and deduced from this what the physical conditions that prevailed in the cloud were. The large amount of information that can be obtained from measuring the light emitted from atoms and molecules has allowed researchers to separate the effects of various processes that affect the gas atoms - collisions with other particles, ultraviolet radiation from the gas's immediate environment, and the cosmic background radiation. Since they were able to isolate the effect of the cosmic background radiation, the researchers were able to measure for the first time the temperature of this radiation as it was more than ten billion years ago, when the light received by the telescope began its long journey across the universe.
The temperature measured by the researchers is between 6 and 14 degrees above absolute zero: at least twice the background radiation temperature today. For the first time, it was directly proven that the cosmic background radiation was hotter in the past, and the measured temperature corresponds to the predictions of the accepted big bang theory. These results are another significant reinforcement of the experimental evidence for the Big Bang theory, and they pose a difficult challenge to alternative cosmological theories.
In this context, it is interesting to note that the method used by Sriyanand and his team to measure the light emitted from a very distant gas cloud can also be used to measure the light of much closer gas clouds located in our galaxy. Such observations make it possible to distinguish the existence of the cosmic background radiation and to measure its temperature today. It turns out that such observations were indeed made about 60 years ago. The researchers who made them actually discovered the cosmic background radiation and measured its temperature, 24 years before its discovery by Penzias Wilson and eight years before its existence was predicted by Gamov. However, although the researchers correctly analyzed the data and concluded that there is an unknown source of radiation affecting gas clouds in the galaxy, they did not understand the far-reaching consequences of their results, neither at the time of their publication nor after the publication of the Big Bang theory by Gamov. In doing so, they missed one of the sensational discoveries in astronomy; A discovery that won, thirty years later, Penzias Wilson the Nobel Prize.
{Appeared in Haaretz newspaper, 20/12/2000}
The interstellar deuterium provided confirmation for the big bang theory
A certain isotope of deuterium had to be formed in the big bang and not inside the stars
6.7.2000
By: David Isshachari, Director of the Vala Science Forum
Another piece of evidence to confirm the "big bang" theory was found through a new measurement of deuterium, a relatively common isotope of hydrogen that contains one proton and one neutron, the measured amount corresponds to an "primordial model", that is, in the big bang (Mg), and not in later galaxies or stars relatively.
A group of astronomers in the United Kingdom used a 12-meter radio telescope to scan a huge molecular cloud located close to the center of our galaxy "only" 30 light-years away, literally KLB. In particular, they focused on the spectrum of the hydrogen cyanide HCN and its isotopic partner the deuterium cyanide. DCN in general, stars are producers of deuterium and not its producers, this means that the deuterium is consumed in the helium production processes, which release the energy of the stars.
The center of the galaxy is a hub of bustling activity. Gas jets, eruptions, X and gamma sources, massive black holes, hot filaments, arcs and other spectacular phenomena that create matter.
From analyzing the spectrum, researchers Don Lubowich, Jay Pasachoff, Tom Balonek, and Tom Millar learned that the element H/D is higher than what is observed in the absence of a primary source of unprocessed material (higher in D, lower in heavier elements). This fact indicates that material rich in D is sprayed from the cloud into the plane of the galaxy (see continuous demonstration). This fact indicates, according to the researchers, that D is not formed in stars and therefore it is
Created in MG.
Also, from the rate of creation of D in quasars and comparing it to that measured in the cloud, it seems that our galaxy did not contain a quasar for at least a billion years, and probably not for 4 billion years.
The original article:
(Lubowich et al., Nature, June 29
2000)
