In the foreseeable part of the Universe, 10-20 times more galaxies than previously thought
Hubble telescope image (Source: NASA / ESA)
The Hubble telescope helped astronomers make an interesting discovery that could affect the entire future of astronomical science. As it turned out, in the foreseeable part of the Universe there are 10-20 times more galaxies than scientists previously thought. This conclusion was made after analyzing a large number of deep space photographs sent to Earth by the Hubble telescope. In the course of their work, scientists also studied other images taken by astronomers at observatories on Earth.
The conclusion that there are more galaxies in the Universe than people thought so far has been madescientists from the University of Nottingham led by Christopher Conselice. Most of these galaxies (approximately 90%) are relatively small and dim, so it's not so easy to spot them. According to scientists, such galaxies are similar to the satellites of the Milky Way. “We missed the vast majority of galaxies because they are too dim and very far away,” says Professor Conselis.
“The real number of galaxies in the Universe is one of the fundamental questions in astronomy, and the fact that more than 90% of the galaxies have not yet been studied is scary. Who knows what interesting properties of these objects we will find when we begin to study galaxies with the help of new generation telescopes? ”The scientist asks.
The video posted above is Carl Sagan's speech at the school, where he explains to the students the vastness of the universe. “In total here (in the foreseeable part of the Universe) there are about 100 billion other galaxies, each of which has about 100 billion stars. Imagine how many stars, planets and life forms can be in this huge and amazing Universe, ” says Sagan.
The Hubble Orbital Telescope helps specialists study the visible part of the universe. It has been working for about 20 years, and for all this time, Earth scientists have received a huge amount of critical information, including data on the number of galaxies in the universe. It was previously believed that in the foreseeable part of the Universe there are 100-200 billion galaxies. But it seems that this number can be safely multiplied by 10 or even 20.
Counting galaxies in the universe is not an easy task. Firstly, as already mentioned above, we do not see most of these objects because of their dullness and small size. The problem, in fact, is not in the galaxies, but that the equipment used by man to observe them is imperfect. Secondly, so far we are able to study only a small fraction of the space that is available for observation. Hubble Deep Field images are just a millionth of what a person could observe. Here's an animation that shows how tiny the area of space that Hubble is watching.
Scientists from the University of Nottingham made their conclusionsafter working on a Hubble snapshot analysis of 15 years. The work was started by graduate student Aaron Wilkinson, who received a large grant for a galaxy counting project. The data he received served as the basis for a much larger study conducted by Professor Conselis with colleagues from the University of Edinburgh and Leiden. They used Wilkinson data, images taken by Hubble, as well as images from other observatories from around the world. Mathematical analysis showed that the density of the "population" of the Universe is higher than it was believed.
In addition, scientists tried to calculate the number of galaxies in the ancient Universe, billions of years ago. In their opinion, in the past there were even more galaxies than now - at least ten times.
“We know that from the moment of their appearance, galaxies developed, merged with other objects, increased in size. The fact that there were more galaxies in the past indicates a very active evolutionary process, which led to the merger of many systems, ”the scientists said in a statement. This evolutionary process is the merging of smaller galaxies into larger objects. New data will help scientists form a more accurate model of the evolution of the universe than ever.
Scientists, talking about a large number of galaxies in the Universe, remembered the Olbers paradox. This is one of the paradoxes of prerelativistic cosmology, which consists in the fact that in a stationary universe uniformly filled with stars (as it was then thought), the brightness of the sky (including the night) should be approximately equal to the brightness of the solar disk. In theory, in the cosmological model of the Big Bang, this paradox is completely resolved by taking into account the finiteness of the speed of light and the finiteness of the age of the Universe.
Why is our sky at night dark and not glowing? We could observe approximately the same picture if the Universe were static (source: Wikipedia)
This point of view is also supported by specialists from the University of Nottingham. They believe that with such a density of galaxies in the Universe, a galaxy can be observed anywhere in the sky of the Earth. But the light from these objects does not reach us for a number of reasons - the expansion of the Universe, clouds of cosmic dust and gas, and other factors.
As for the number of galaxies in the universe, the calculations are still ongoing. This work is not easy to do, so astronomers will need a lot of time to build a more accurate model of the universe.