Exactly 100 years ago, our concept of the Universe was very different from today’s. People knew about the stars in the milky Way and knew the distances to them, but what no one knew. The universe believed static, spirals and ellipses in the sky thought objects in our own galaxy. Newtonian gravity has not yet been surpassed by a new theory of Einstein, and scientific ideas like the Big Bang, dark matter and the dark matter was not at the hearing. But then, literally from every decade, began to happen; breakouts for breakouts, and so on until today. Before you chronicle Ethan Siegel Medium.com of how to change our view of the Universe in the last hundred years.
The results of the expedition of Eddington in 1919 showed that the General theory of relativity describes the bending of star light near massive objects
1910 years: Einstein’s theory was confirmed. General relativity became known, which gave predictions that could not give the theory of Newton: the precession of mercury’s orbit around the Sun. But for scientific theories was not enough just to explain something that we have seen; she had to make predictions about what we haven’t seen yet. Although in the last hundred years there were lots of gravitational time dilation, strong and weak lensing, gravitational red shift and so on — the first was the bending of starlight during a total solar Eclipse that was observed by Eddington and his colleagues in 1919. A measure of the curvature of light around the Sun was incompatible with Einstein’s predictions and were not correlated with the theory of Newton. Since then, our understanding of the Universe changed forever.
Discovery Hubble Cepheid variable in the Andromeda galaxy, M31, has opened our Universe
1920-e years. We do not yet know that beyond the milky Way is the universe, but that all changed in the 1920s with the work of Edwin Hubble. Watching some of the spiral nebulae in the sky, he was able to pinpoint the individual variable stars of the same type that was known in the milky Way. Only the brightness was so low that it is directly pointed to the millions of light years that lies between us, placing it far outside our galaxy. The Hubble did not stop there. He measured the speed of recession and distance to dozens of galaxies, significantly expanding the boundaries of the known Universe.
Two bright and large galaxy in the center of the Coma cluster, NGC 4889 (left) and a little smaller NGC 4874 (right), each more than a million light years in size. Through the cluster, as suggested, is a huge dark matter halo
1930. For a long time it was believed that if you could measure the whole mass contained in the stars, and possibly add gas and dust, you would be able to count all the matter in the Universe. However, observing galaxies in a dense cluster (like Coma cluster), Fritz Zwicky showed that stars and so-called “normal matter” (atoms) is not sufficient to explain the internal motion of the clusters. He called the new matter dark matter (dunkle materie), and up to the 1970’s, his observations were largely ignored. Then ordinary matter studied better and it turned out that dark matter contains quite a lot of separate rotating galaxies. Now we know that dark matter mass exceeds the usual 5 times.
1940. Although most of the experimental and observational resources left reconnaissance satellites, missile engineering and development of nuclear technology, theoretical physicists continued to work tirelessly. In 1945, George Gamow developed a full extrapolation of expanding Universe: if the universe expands and cools once in the past, it should have been denser and hotter. Therefore, once in the past there was a time when the universe was too hot and neutral atoms couldn’t form, and before that atomic nuclei could not form. If so, then before the formation of any stars matter of the Universe began with the lightest elements, and nowadays it is possible to observe the afterglow temperature in all directions — only a few degrees above absolute zero. Today this theory is known as the Big Bang theory, and in 1940-ies did not even know how great it is.
1950. The competing idea of the Big Bang hypothesis was stationary model of the Universe proposed by Fred Hoyle and others. Tellingly, both sides claimed that all the heavy elements present on Earth today was created in the early Universe. Hoyle and his colleagues claimed that they were not made in the early, hot, dense state, but rather in previous generations of stars. Hoyle, together with his colleagues, Willie Fowler and Margaret Burbidge, explained in detail, as elements to build the periodic table in the process of nuclear fusion in stars. Interestingly enough, they predicted the synthesis of carbon from helium in a process that we had never before observed: the triple alpha process, which requires the existence of a new state of carbon. This condition was discovered by Fowler a few years after the original forecast Hoyle and is today known as the Hoyle state of carbon. So, we found out that all the heavy elements existing on Earth have their origin in all previous generations of stars.
If we could see microwave light, the night sky would look like a green oval with a temperature of 2.7 Kelvin, with the “noise” in the center, made hot by the contributions of our galactic plane. This uniform radiation with cerotelium range indicates the afterglow of the Big Bang is the cosmic microwave background
1960s. After 20 years of discussions, the key observation which would determine the history of the Universe was made: the discovery of the predicted afterglow from the Big Bang, or cosmic microwave background. This uniform radiation with a temperature of 2,725 Kelvin was discovered in 1965 by Arno Penzias and Bob Wilson, none of whom realized immediately that came. Only with time ternately spectrum of this radiation and its fluctuations were measured and showed that our universe began with “explosion”.
The earliest stage of the Universe before the Big Bang, laid all the initial conditions for all that we see today. It was a great idea Alan Guth: cosmic inflation
1970. At the end of the 1979 young scientist hatched his idea. Alan Guth was looking for a way to resolve some of the unexplained problems of the Big Bang — why the universe is so flat space, why is it the same temperature in all directions and why are there no relics of the higher energies — and came to the idea of cosmic inflation. According to this idea, before the universe came in a hot dense state, was a state of exponential expansion, when all the energy was inherent in the fabric of space. It took several improvements of the original ideas of ghouta, to form the modern theory of inflation, but subsequent observations — including fluctuations in the cosmic microwave background, confirmed her prediction. The universe not only began with the explosion, but she had other special status, even before there was this Big Explosion.
The remains of supernova 1987a located in the Large Magellanic cloud, 165 000 light-years from us. Over three hundred centuries, it was the closest observed supernova to Earth
1980. It may seem that was nothing serious, but in 1987 from the Ground observed the closest supernova. This happens once in a hundred years. It was also the first supernova that happened when we had the detectors are able to find neutrinos, born in the course of such events. Although we have seen many supernovae in other galaxies, we have never observed them so close to witness the neutrino from them. These neutrinos 20 or so marked the beginning of neutrino astronomy and the subsequent developments that led to the oscillations neutrinos, the discovery of neutrino masses and neutrinos from supernovae that occur in galaxies millions of light-years from us. If modern our detectors were functioning at the right time, the next supernova would catch hundreds of thousands of neutrinos.
Four possible fates of the Universe, the last of which best fits the data: the universe is dark energy. It was first discovered through observations of distant supernovae
1990. If you thought that dark matter and opening of the beginning of the Universe was a major discovery, imagine what a shock was in 1998, when he discovered that the Universe is waiting for the end. Historically, we imagined three possible fates:
- The expansion of the Universe will be insufficient to overcome the gravitational pull of everything, and the universe will shrink again in the Great Compression
- The expansion of the Universe will be too much, and all of the combined gravity will scatter, and the universe will freeze
- Or we will find ourselves on the border of these two outcomes and the rate of expansion will asymptotically tend to zero, but will never attain: a Critical universe
Instead, however, of distant supernovae showed that the expansion of the Universe is accelerating and that as of the expiration time of a distant galaxy faster move away from each other. The universe doesn’t just freeze, but all galaxies that are not bound to one another, ultimately disappears over our cosmic horizon. In addition to the galaxies in our local group, no milky Way galaxy will not meet, and our fate is cold and lonely. In 100 billion years we will not see any galaxies besides our own.
2000. Our measurements of the fluctuations (or imperfections) of the afterglow of the Big Bang has taught us incredible: we learned exactly what the universe is made. Data from COBE data is replaced with WMAP, which, in turn, improved plank. All together, the data of large-scale structures from large surveys of galaxies (like 2dF and SDSS) and data for distant supernovae have given us the modern picture of the Universe:
- 0.01% of the radiation in the form of photons
- 0.1% of neutrinos, which make a light contribution to the gravitational halos surrounding galaxies and clusters,
- 4.9% of ordinary matter, which includes all composed of atomic particles,
- 27% of dark matter or the mysterious, non-interacting (except for gravity) particles, which provide the structure of the Universe that we observe,
- 68% dark energy, which is inherent to the space.
2010-e. This decade is not over yet, but we already found our first potentially habitable planet similar to Earth (though very remotely), among the thousands and thousands of new exoplanets discovered by the mission “Kepler” NASA. It may not be the biggest discovery of the decade, because the direct detection of gravitational waves LIGO is made, confirmed the picture painted by Einstein in 1915. After more than a century after Einstein’s theory was first challenged Newton, General relativity has passed through all the trials and tests that have been proposed.
Scientific history is still being written and there is much in the Universe to be discovered. But these 11 steps that brought us out of the Universe of unknown age, no bigger than our galaxy, consisting mostly of stars in an expanding, cooling Universe governed by dark matter, dark energy and our ordinary matter. There are many potentially habitable planets, it is 13.8 billion years old, and it started with the Big Bang, which itself emerged from the cosmic inflation. We learned about the origin of the Universe, her fate, the appearance, structure and size — all in 100 years. Perhaps the next 100 years will be full of surprises that we can’t even imagine.
11 scientific achievements of the last 100 years that gave us the Universe
Ilya Hel