May God protect you and fulfill your wish that you do for another and it is for your sake that you touch every star and climb every step that you stay young forever "May you stay young forever" Words and music: Bob Dylan Translation: Yair Lapid Performance of the Hebrew version: Rami Kleinstein
The Institute
Mapping the cosmic rip radiation in the universe as performed by the WAMP research satellite in 2003. This experiment confirmed the data obtained in two previous experiments in which Prof. Hanani participated: Archeeops whose data (published in 2002) are described in the upper defined field; and MAXIMA, which was performed with increased resolution and sensitivity, and its data (published in 2002) appear in the square defined in the center
If the universe, which started about 15 billion years ago with a big bang, will come to an end with a thin whimper, as Robert Frost's well-known poem says? The answer to this question depends not a little on the nature and amount of matter in the universe. Prof. Shaul Hanani, from the University of Minnesota in the USA, who recently served as a visiting professor at the institute, focuses on studies designed to shed light on this mystery through observations, measurements and analyzes of the cosmic background radiation, which is the residual radiation from the first moments of the Big Bang.
As we know, the prevailing view of cosmologists says that about 15 billion years ago the entire universe, with its matter and energy, was confined in a very small area, hot and immeasurably compressed. Then, at some point, for some unknown reason (perhaps as a result of someone, or something, saying "let there be light"), the universe began to rapidly expand. This is the "big bang". In the process of the expansion of the young universe, the matter spread everywhere, creating a kind of hot and dense primordial soup.
One of the questions that occupied cosmologists for a long time was the question of the organization of separate blocks of matter. If the "soup" was indeed completely uniform, then there would be no reason for the spontaneous organization of lumps of matter within it. In other words, if the "soup" was indeed uniform, then today's universe would still appear to be a kind of uniform "soup" that has neither galaxies, nor stars, nor planets, nor beings that can ask any questions about the nature of the "soup".
Prof. Shaul Hanani. looking back
The fact that the universe known to us is organized as it is organized led to the raising of a hypothesis, according to which the "Genesis soup" was not so uniform, and that, in fact, different areas of it differed from each other with tiny differences, a kind of "ripples" or "wrinkles", in the density of the material. Over time and under the influence of gravity, the differences between the different regions grew stronger, and caused the separation of lumps of matter from the "primitive soup". In areas that were slightly denser, the galaxies and galaxy clusters that we see today were formed, and less dense areas became vast voids. The crystallization process in which galaxies were formed, in which the stars were formed around which the planets were formed, and on one of which (at least) life was formed that enables - among other things - the occupation of the question of the creation of the universe, took about 15 billion years.
In April 1992, this hypothesis was confirmed, when the COBE research satellite was able to look back in time and pick up the background radiation of the universe as it was only about 30,000 years after the Big Bang. The cosmic background radiation, first discovered by Arnaud Panzias and Robert Wilson in 1965 (who won Thus in the Nobel Prize for Physics in 1978), is the residual radiation of the Big Bang.
COBE's measurements showed that the background radiation spectrum corresponds to that of black body radiation; That is, the intensity of the radiation
at some point corresponds in a certain ratio to the densities of matter and energy that existed at that point in the young universe. This was an important proof of the correctness of the "Big Bang" model, since this model predicted that the background radiation would be characterized by the properties of black body radiation. The COBE satellite also found tiny differences in the background radiation coming from different points in the universe. These differences were the buds from which the structures that make up the universe as we know it today grew and developed: galaxy clusters, galaxies, and more.
At its peak intensity, the cosmic background radiation reaches a wavelength of one millimeter. Unfortunately, the atmosphere absorbs the radiation at this wavelength and prevents it from reaching the earth's surface, so measuring facilities placed on Earth cannot pick it up. Therefore, scientists who want to measure this radiation are forced to use satellites, or special research balloons.
Prof. Hanani's research focuses on the effort to understand the nature of the intensity differences in the background radiation coming from different places in the sky. In this way, the scientists aim to reveal the characteristics of the ancient universe, something that may teach us, among other things, about its future, and even about the nature of the end of the universe. Prof. Hanani: "In the very young universe, the radiation was adjacent to the matter in the universe, and only in the process of expansion and cooling did the radiation separate from the matter. But, their shared past means that the radiation differences we measure today accurately describe the differences in matter and energy density that existed in those places in the early universe. In this sense, measuring the cosmic background radiation is the only tool that allows us to observe the early universe."
In this sense, the cosmic background radiation appears to be the music of the eternally young universe. Prof. Hanani: "This is the closest direct measurement to the formation of the universe that we are able to perform. Beyond the limit of this measurement (300,000 years after the Big Bang), we can only infer, and build different models, but not receive direct evidence." Since the first measurement of the COBE research satellite, additional measurements and experiments have been performed, which provide improvements in the resolution level of the measurement.
One of the most accurate mappings of the cosmic background radiation was achieved in two experiments in which Prof. Hanani participates. Both experiments were carried out using research balloons, one of which was sent and landed in the USA, and the other - in Northern Europe. The results of the experiments allowed Hanani and his partners to deduce the density of matter in the universe. Using these results and other astrophysical measurements, Hanani and his partners also calculated the densities of the different types of matter. The experiment revealed that the universe is characterized by a flat structure, and that the normal matter we all know, the one made for example of protons, neutrons and electrons, constitutes only five percent of all the matter in the universe. All the other 95% of matter consists of two types of matter whose characteristics and nature we do not properly understand. The results were included in the list of the ten most important scientific discoveries of the year 2000, as chosen by the editors of the scientific journal "Science".
The first type of unknown matter, which makes up about 30% of the matter in the universe, is "dark matter" which we cannot see with any electromagnetic observation means (including visible light), but we can sense and measure its gravitational effect. The second type of unknown matter, which makes up about 65% of the matter in the universe, is also dark and we cannot observe it in any way, but its gravitational effect is also different. All "normal" types of matter exert a gravitational force, that is, they attract other matter clusters to them, which slows down the expansion of the universe. But this unknown and incomprehensible matter, which as mentioned makes up most of the matter in the universe, causes the expansion of the universe to accelerate. In a certain sense, it seems that this unknown substance activates "negative gravity" out of nowhere that works (with great success) against normal gravity.
If the phenomenon is recovered, then it is expected that the rate of expansion of the universe will continuously accelerate, and this will result in the distances separating the galaxies in the universe expanding and decreasing. And so, in a few tens of billions of years, the earth and our galaxy, the "Milky Way", will be found in a state of unglamorous loneliness, alone in the expanses of the universe, when all the other galaxies will move away from us to vast distances and disappear from sight. Prof. Hanani and his research partners are now tracing the polarization properties of the cosmic background radiation, which may allow them to obtain information about the early universe as it was a tiny fraction of a second after the "big bang". Prof. Hanani: "It will be a rare experience to learn about the state of the universe as it existed so close to the moment of its birth in the Big Bang."
Astrophysics connoisseur - the universe
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