A balloon launched outside the atmosphere reveals the appearance of the universe when it was only 300 thousand years old * Findings of three new experiments on the background radiation * Three new studies on the cosmic background radiation provided quantitative data, regarding the amount of matter in the universe, the proportion of dark matter and dark energy
In the picture: the universe in its beginnings from "Boomerang". The different colors indicate differences in the temperature of the radiation in the image: using such a balloon sent to the heights of the South Pole continent, disturbances in the intensity of radiation of matter in the universe were measured: the "Boomerang" experiment
Three teams of scientists (and among them - as in the study reported above there was an Israeli researcher) have now provided numerical data on the amount of matter in the universe and quantitative estimates regarding the proportion of dark matter and dark energy. There is no consensus on all the data presented at the American Physical Society conference held last month. But from the three works it appears that the proportion of ordinary matter in the universe is only 5 percent. The proportion of dark matter was calculated to be 30 percent and the proportion of dark energy to 65 percent.
The scientists who reported this were measuring the background radiation in the universe. Their works supported the theory dealing with the ancient "inflationary universe" and shed light for the first time on the development of tiny disturbances that occurred in the density of the ancient universe until the formation of the largest structures we know today.
Results of two experiments on this subject were obtained from prolonged flights of balloons; The third experiment was carried out in a ground instrument operating at the American research station in the South Pole. The cosmic background radiation was released from its coupling, the primordial matter - hundreds of thousands of years after the "big bang". The unique event in which the universe was created - happened about 13-12.5 billion years ago.
In its initial moments - this is how the scientists describe it - the universe was just a turbulent sea of particles and radiation that mixed with each other, creating new particles and canceling them out.
The radiation was close to the material, due to the absorption of photons (light particles). Pairs of a particle and an antiparticle were created, and photons were released - in accidental encounters of such pairs. Only when the electrons joined the nuclei - created in the first three minutes of the universe - could the photons propagate, unhindered. Today, they can be picked up with measuring devices.
The matter and energy mixed in the early universe created an almost uniform "background". The fate of density disturbances was somewhat similar to the sound waves propagating in the air: which develop and disappear. When the disturbance is greater, they develop.
After a certain period, a disturbance that does not disappear and only increases over time - may cause a piece of matter to detach from everything else - and shrink due to its own gravity.
From these first disturbances were born, after hundreds of millions of years, the initial galaxy clusters, which are seen today as a collection of thousands of galaxies concentrated in a defined place, in space.
If one wants to investigate the state of disturbances in the primordial universe, one must look for them in the slight changes that occur in the intensity of the radiation, between one region and another, in the sky. This slight change is a signature of local agglomerations of the matter of the early universe.
The "Kobe" spacecraft studied the cosmic background radiation and measured the temperature of the region from which it was emitted. She was unable to characterize the changes that occurred in the radiation intensity, due to the angular separation in the detectors. These took a blurry picture of the area from which the radiation was emitted. Only with the help of newer tools, developed for this purpose, was this research deepened.
The new tools for this mission were hung on balloons, which sail high above the Antarctic continent.
The first results of one of these experiments-the machine
"Boomerang" - were published about a year ago and generally confirmed the assumptions that had accumulated, including a photo, regarding the aforementioned first disorders. The conclusion: most of the disturbances occurred at an angular distance between disturbance and disturbance. This distance is all on the order of 1 degree (which means: twice the size of the full moon).
These were the biggest disturbances in the radiation that was released from the matter, at the second of the universe's formation. The discovery confirmed the theory of the inflationary universe and also the assumption that the universe is "flat" and expanding forever.
The entire study was defined as the "discovery of the year". Measuring the smallest perturbations that occurred in the intensity of the radiation—corresponding to smaller perturbations than those that formed the large clusters of galaxies.
At the conference, the "Boomerang" project team reported on the smaller disturbances found in the experiment - following a reprocessing of the entirety of the data captured in its balloon. At the same time, the results of the ground experiment, which was carried out from the South Pole, were presented. They matched those of "Boomerang". This is also the case with another experiment called "Maxima" in which the Israeli partner Dr. Shaul Hanani (now at the University of Minnesota in the USA) was involved.
The data not only confirm the picture of the inflationary universe - also make it possible to determine which part of the universe's content is in the form of ordinary matter (not radiation and exotic particles, or free energy). This part is calculated to be about 5% of the contents of the universe.
On the other hand, the numbers dealing with the amount of dark matter and dark energy are less certain. We now see that 30% of the contents of the universe is dark matter (particles whose nature is currently unknown) and about 65% of the universe is dark energy, which resides in particles that are born and immediately die everywhere in the universe.
An international team of cosmologists published yesterday the clearest picture of the early universe, from the time when there were no stars yet, and space was full of hot, compressed gas. To an untrained observer, the photographs look like a collection of meaningless blobs.
This is a project in which a balloon known as a "boomerang" is launched into the atmosphere. The data collected by the instruments on the balloon provide cosmologists with unprecedented confirmation of some of the most important theories about the nature of the universe and how it evolved.
The new study appears to be the most accurate and detailed verification yet of the Big Bang theory. According to the theory, the universe in the beginning was made of highly compressed gas. At some point there was a huge explosion, known as the "Big Bang", and the universe began to expand. Over time, differences began to arise in the density of the material in it. Indeed, the analysis of the microwave rays revealed a similar picture of a homogeneous universe with very small deviations in the degree of compactness of matter.
The "boomerang" picks up microwave rays, which cosmologists call the "cosmic background radiation", which reach the earth from the far reaches of the universe. Since the microwave rays advance at a constant speed (the speed of light), some of the rays that reach the earth today started their way when the universe was only 300,000 years old (the age of the universe today is about 15-12 billion years).
The spots in the photographs actually reflect temperature differences in the microwave radiation reaching the earth from all directions in the sky. The temperature differences of the microwave radiation reflect the universe at its beginning: places where the temperature of the radiation is relatively high, indicate a high density of matter; Places where the temperature is relatively low indicate that the material is less dense.
"The Big Bang theory has now passed a very important test," says astrophysicist Prof. Avishai Dekel, head of the Rakach Institute for Physics at the Hebrew University. "The new results confirm the standard cosmological model of a big bang, followed by inflationary expansion."
The study published yesterday in the scientific journal "Nature" has already aroused great excitement among cosmologists who have been waiting for its results for a long time. Another important result confirms theoretical models according to which the universe is "flat", or in astronomical terms: two parallel rays of light will never meet. This is in contrast to other possibilities, raised in Einstein's theory of general relativity, according to which space can be "curved" in different ways, so that parallel lines can meet.
However, the photographs also surprised some cosmologists in what they did not show: according to most theoretical models, "Boomerang" should have noticed even the smallest temperature differences of the microwave radiation. "Boomerang" did not notice them, and the researchers are trying to find out today why.
{Appeared in Haaretz newspaper, 28/4/2000{
What is the age of the universe?
For many years astronomers struggled to calculate the age of the universe. Their estimates ranged from 10 to 20 billion years, a frustrating field in terms of its space. These debates continued until the launch of the Hubble Space Telescope, named after the astronomer who began 70 years ago to investigate the age of the universe.
Edwin Hubble discovered that the rate at which galaxies are receding from each other is proportional to their distance. The expansion rate Hubble's constant is the key to calculating the age and size of the universe. But to identify the constant unequivocally, precise measurements of the distant galaxies must be made.
In May 1999, a team led by Wendy Freeman from the Carnegie Institution in Washington, DC, published the results of the measurements they made with the Hubble telescope during the eight years that Hubble had been making observations until then.
The universe is expanding at a rate of 21 kilometers per second per million light years. Hence the approximate age of the universe is 12 billion years, roughly the age of the oldest stars. The new number relieves scientists of an embarrassing mystery: earlier estimates suggested that the universe is younger than the age of its elderly stars.
"Finally, after all these years," says Freeman, "we have entered the era of precise cosmology. From now on we can turn to the broader picture of the origin of the universe, its development and its future." Is the new number really the last word? not exactly. In June 1999, astronomers using an extensive array of radio telescopes reported measurements for a distant galaxy that "rejuvenates" the universe by 15 percent compared to Hubble's results.
By: Tamara Traubman * The Hidan site was until 2002 part of the IOL portal from the Haaretz group
