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Nobel laureate Prof. Peebles revealed the secrets behind cosmic radiation

Nobel laureate in physics for 2019 James Peebles took it upon himself to face the entire universe, for all the billions of galaxies and clusters of galaxies within it. The theoretical framework he developed over two decades is the basis for his modern understanding of the history of the universe, starting with the Big Bang and ending with the present day, the members of the prize committee write. In this article we will expand on the importance of Prof. Peebles' discovery

The 2019 Nobel Prize in Physics is being awarded for new insights into the structure and history of the universe, and for the first-ever discovery of the holiday planet around a sun-like star outside our solar system. These discoveries forever changed our understanding of the world we live in.

Nobel laureate in physics for 2019 James Peebles took it upon himself to face the entire universe, for all the billions of galaxies and clusters of galaxies within it. The theoretical framework he developed over two decades forms the basis

For his modern understanding of the history of the universe, beginning with the Big Bang and ending with the present day.

The Genesis of Big Bang Cosmology

The last five decades constitute the golden age of the world of cosmology, the study of the creation and development of our universe. In the 1971s, the groundwork was laid that would shift the field of cosmology from mere speculation to solid science. The key researcher in this change was James Peebles, whose proven discoveries put the field of cosmology on the scientific map, while enriching the entire field of research. The first book he published, Physical Cosmology (XNUMX), inspired an entire generation of physicists who continued to contribute to the development of the field, not only through theoretical hypotheses but also based on observations and measurements. Science, and only it, will be able to give answers to the basic questions regarding the source of our origin and the place to which we are progressing; The field of cosmology has freed itself from human ideas such as faith and existential meaning. This development echoes the words of Albert Einstein from the beginning of the last century who stated that the mystery of the world is its complete understanding.
The story of the universe, a scientific narrative of the evolution of the world, has only become familiar during the last hundred years. Earlier, the universe was seen as a stationary and eternal structure, but in the XNUMXs astronomers discovered that all galaxies are moving away from each other and from our galaxy. The universe is expanding. We now know that the present universe is different from yesterday's and will be different from tomorrow's as well.
What the astronomers saw in the sky was already predicted by Albert Einstein in the framework of the theory of relativity back in 1916, the theory that today forms the basis of all large-scale calculations of the universe. When Einstein discovered that his theory leads to the conclusion that the universe is expanding, he added a proviso to his equations (the cosmic constant) which would balance the effects of gravity and without it the universe would become a stagnant universe. Over the next decade, once the expansion of the universe was clearly observed, this caveat was no longer required. Einstein referred to this caveat as the greatest conceptualization of his life. He had no idea that the cosmological constant would return to the forefront of the scientific field of cosmology in the XNUMXs, thanks in no small part to the research contributions of James Peebles.

In this map, built on the basis of the observations of the Planck spacecraft launched by the European Space Agency, you can see the cosmic microwave background radiation (CMB), the earliest observable light of the universe, and it gives us the best picture ever of the universe in its early childhood. The blue areas in the sky represent points where the temperature of the background radiation, and in any case also of the early universe, is lower, and the red areas reflect warmer places. Proponents of the inflationary theory, which holds that the universe expanded rapidly in its early moments, argue that the pattern of hot and cold spots is consistent with this idea. However, the theory can actually produce any pattern, and in most of its versions it produces larger temperature differences than this map shows. Moreover, if inflation did occur, the background radiation should include evidence for cosmic gravitational waves, ripples in spacetime caused by the primordial stretch, but it does not. Instead, the Planck data reveal that the true story of our universe's history is still far from over. Source: ESA and the Planck Collaboration.
A childhood picture of the universe
In this map, built on the basis of the observations of the Planck spacecraft launched by the European Space Agency, you can see the cosmic microwave background radiation (CMB), the earliest observable light of the universe, and it gives us the best picture ever of the universe in its early childhood. The blue areas in the sky represent points where the temperature of the background radiation, and in any case also of the early universe, is lower, and the red areas reflect warmer places. Proponents of the inflationary theory, which holds that the universe expanded rapidly in its early moments, argue that the pattern of hot and cold spots is consistent with this idea. However, the theory can actually produce any pattern, and in most of its versions it produces larger temperature differences than this map shows. Moreover, if inflation did occur, the background radiation should include evidence for cosmic gravitational waves, ripples in spacetime caused by the primordial stretch, but it does not. Instead, the Planck data reveal that the true story of our universe's history is still far from over. Source: ESA and the Planck Collaboration.

The first rays of the universe reveal all

The expansion of the universe means that in the past it was much more dense and hot. In the middle of the XNUMXth century, the beginning of the universe was given the name 'The Big Bang'. No one really knows what happened in the beginning, but the primordial universe was full of a dense, fiery and dim collection of particles, which, when exposed to them, the light particles, protons, simply scattered around.

It took almost four hundred thousand years of expansion for this primordial assemblage to cool to several thousand degrees Celsius. The original particles could join together, creating a transparent gas composed mostly of hydrogen and helium atoms. Only now could the photons move freely so that light could pass through space. These first rays still fill the universe. The expansion of space resulted in the expansion of waves in the visible light range so that they became waves in the invisible microwave range, with a wavelength of a few millimeters.

The glow from the creation of the universe was captured for the first time by chance, in 1964, by two American astronomers: 1978 Nobel laureates Robert Wilson and Arno Penzias. They failed to measure the constant noise that their antenna picked up from space, so they tried to find an answer in the research of others, including the research of James Peebles, who formulated theoretical calculations of this background radiation. After almost fourteen million years, its temperature has dropped to near absolute zero (minus 273 degrees Celsius). The significant breakthrough came when Peebles realized that the radiation temperature could provide information regarding the amount of matter created at the moment of the Big Bang, and realized that this amount could determine how much matter could later form the galaxies and clusters of galaxies that are in the universe today.

The discovery of microwave radiation ushered in the new age of modern cosmology. The primordial radiation from the creation of the universe has become a gold mine that hides within it the answers to almost all the questions that cosmologists want to answer - how old is the universe? What will be his fate? What is the amount of matter and energy present in it?

Scientists are able to measure traces of the universe's earliest moments with this primordial glow, tiny changes that travel like sound waves through this primordial assembly. Without these tiny changes, the universes would cool from a hot ball of fire into a uniform frozen chaos. We know today that this event did not happen, and that space is full of galaxies, which are usually gathered into galaxy clusters. The background radiation is smooth and uniform, similar to the surface of the ocean water; The waves are revealed up close, ripples that reveal the tiny changes that have happened since the early universe.

Study after study, James Peebles led the interpretation of these primordial traces dating back to the earliest ages of the universe. With incredible precision, cosmologists have been able to provide predictions regarding changes in background radiation and show how they affect matter and energy in the universe.

The first breakthrough in terms of observation came in April 1992, when principal researchers in the American COBE satellite project published an image of the first rays ever in the universe (the Nobel Prize in Physics for 2006 was awarded to the two researchers John Cromwell Mather and George Smoot). Other satellites (the American WMAP and the Planck Space Telescope) gradually increased the resolution of the images from the young universe. Just as predicted, the change in background radiation temperature was measured as thousandths of a degree Celsius. With the improvement in the level of accuracy, the theoretical calculations of the matter and energy included in the universe have become precise measurements, with ninety-five percent of this amount hidden from us.

See also an interview with Prof. Peebles' colleague, Prof. Yoel Rafali from Tel Aviv University: "Nobel winner Jim Peebles led theoretical research in cosmology for decades"

and information about the win:The discoverers of the first planet outside the solar system and the key to the cosmological theory were jointly awarded the Nobel Prize in Physics

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