Presentation of the evolution of the universe for 13.77 billion years. The far left depicts the earliest moment we can now explore, when a period of “inflation” caused a burst of exponential growth in the universe. (The size is shown by the vertical size of the lattice in this graph.) Over the next few billion years, the expansion of the universe gradually slowed as matter in the universe was pulled by gravity. More recently, expansion has begun to accelerate again, as the repulsive effects of dark energy have begun to dominate the expansion of the universe. Credit: NASA’s Goddard Space Flight Center
Three decades of space telescope observations approach the exact value of the Hubble constant
The history of science will record that the search for the speed of expansion of the universe is the great Holy Grail of 20th century cosmology. Without any observational evidence of expansion, contraction, or stagnation of space, we would have no idea whether the universe was coming or going. Besides, we wouldn’t have any idea of his age — or, in fact, if the universe were eternal.
The first action of this revelation happened when a century ago the American astronomer Edwin Hubble discovered countless galaxies outside our native galaxy, the Milky Way. And the galaxies did not stand still. Hubble found that the farther a galaxy was, the faster it seemed to move away from us. This can be interpreted as an even expansion of space. Hubble even said that he studied galaxies simply as “markers of space.” However, he was never completely convinced of the idea of a steadily expanding universe. He suspected that his measurements might be evidence of something more strange happening in the universe.
“You get the most accurate measure of the rate of expansion of the universe from the gold standard of telescopes and space mile markers.” – Nobel Laureate Adam Rhys
For decades after Hubble, astronomers have worked to determine the rate of expansion that would lead to a true age for the universe. This requires the construction of a series of space ladders for distance, assembled from sources in which astronomers have reasonable confidence in their inherent brightness. The brightest and therefore the most distant markers for cute poles are the type Ia supernovae.
When the Hubble Space Telescope was launched in 1990, the rate of expansion of the universe was so uncertain that it could be only 8 billion years or even 20 billion years old.
After 30 years of meticulous work with the extraordinary observational power of the Hubble Space Telescope, many teams of astronomers have narrowed the degree of expansion to an accuracy of just over 1%. This can be used to predict that the universe will double in size in 10 billion years.
The measurement is about eight times more accurate than Hubble’s expected ability. But this has become more than just refining the number to cosmologists. Meanwhile, the mystery of the dark energy that pushes the universe apart has been revealed. To complicate matters further, the current rate of expansion is different than expected, as the universe appeared shortly after the Big Bang.
You think this would disappoint astronomers, but instead it opens the door to discovering new physics and asking unexpected questions about the basic mechanisms of the universe. Finally, to remind us that we still have a lot to learn among the stars.
This collection of 36 images from NASA’s Hubble Space Telescope includes galaxies that host both Cepheid variables and supernovae. These two celestial phenomena are both important tools used by astronomers to determine astronomical distance, and have been used to refine our measurement of the Hubble constant, the rate of expansion of the universe. The galaxies shown in this image (top row, bottom left row, right row) are: NGC 7541, NGC 3021, NGC 5643, NGC 3254, NGC 3147, NGC 105, NGC 2608, NGC 3583, NGC 3147, Mrk 1337, NGC 1357, NGC161, NGC 19, NGC 135, NGC 135, NGC 131, NGC 19, NGC 135, NGC 19, NGC, NGC 7678, NGC 2442, NGC 5468, NGC 5917, NGC 4639, NGC 3972, Antennae Galaxies, NGC 5584 , M106, NGC 7250, NGC 3370, NGC 3370, NGC 3170, NGC 3370, NGC 3370 4680, M101, NGC 1365, NGC 7329 and NGC 3447. Credit: NASA, ESA, Adam G. Rice (STScI, JHU)
Hubble reaches a new stage in the mystery of the speed of expansion of the universe
NASA’s Hubble Space Telescope has completed a nearly 30-year marathon, calibrating more than 40 “mileage markers” of space and time to allow scientists to accurately calculate the speed of space expansion – a reversal mission.
The pursuit of the rate of expansion of the universe began in the 1920s with measurements by astronomers Edwin P. Hubble and Georges Lemaître. In 1998, this led to the discovery of “dark energy”, a mysterious repulsive force that accelerates the expansion of the universe. In recent years, thanks to data from Hubble and other telescopes, astronomers have discovered another strange twist: a mismatch between the rate of expansion measured in the local universe, compared to independent observations from just after the Big Bang that predict different values of expansion.
The reason for this discrepancy remains a mystery. But Hubble’s data, covering various space objects that serve as distance markers, supports the idea that something strange is happening, possibly involving brand new physics.
“You get the most accurate measure of the rate of expansion of the universe from the gold standard of telescopes and space mile markers,” said Nobel laureate Adam Rees of the Space Telescope Institute (STScI) and Johns Hopkins University in Baltimore, Maryland. .
Riess is leading a scientific collaboration to study the rate of expansion of the universe, called SHOES, which means Supernova, H0, for the equation of state of dark energy. “That’s why the Hubble Space Telescope was created, using the best techniques we know to do it. This is probably Hubble’s greatest work, because it will take another 30 years of Hubble’s life to double even that sample size, “said Rhys.
The Riess team’s paper, which will be published in The Astrophysical Journal’s Special Focus, announces the completion of the largest and probably last major update to the Hubble constant. The new results more than double the previous sample of space distance markers. His team is also re-analyzing all previous data, with the entire dataset already including more than 1,000 Hubble orbits.
When NASA designed a large space telescope in the 1970s, one of the main justifications for the cost and extraordinary technical effort was to be able to solve the Cepheids, stars that shine and darken periodically observed in our Milky Way and outer galaxies. Cepheids have long been the gold standard for cosmic mile markers since their usefulness was discovered by astronomer Henrietta Swan Liavit in 1912. Astronomers use exploding stars called Type Ia supernovae to calculate much greater distances.
Combined, these objects built the “space ladder” in the universe and are essential for measuring the rate of expansion of the universe, called the Hubble constant after Edwin Hubble. This value is crucial in estimating the age of the universe and provides a basic test of our understanding of the universe.
Beginning immediately after Hubble’s launch in 1990, the first set of observations of Cepheid stars to refine Hubble’s constant was made by two teams: the HST Key Project, led by Wendy Friedman, Robert Kenick and Jeremy Mold, Mark Aaronson, and others. by Alan Sandage and co-workers who used the Cepheids as markers for miles to refine the distance to nearby galaxies. By the early 2000s, the teams had declared “mission accomplished,” reaching an accuracy of 10 percent for the Hubble constant, 72 plus or minus 8 kilometers per second per megaparsec.
In 2005 and again in 2009, the addition of powerful new cameras aboard the Hubble Space Telescope launched Generation 2 of Hubble’s ongoing research, as teams set out to refine the value to an accuracy of just one percent. This was discovered by the SHOES program. Several teams of astronomers using Hubble, including SHOES, have come close to a Hubble constant of 73 plus or minus 1 kilometer per second per megaparsec. While other approaches have been used to study the question of the Hubble constant, different teams have come up with values close to the same number.
The SHOES team includes longtime leaders Dr. Wenlong Yuan of Johns Hopkins University, Dr. Lucas Macri of Texas A&M University, Dr. Stefano Casertano of STScI and Dr. Dan Skolnik of Duke University. The project is designed to unite the universe by comparing the precision of the Hubble constant derived from the study of cosmic microwave background radiation left over from the dawn of the universe.
“Hubble’s constant is a very special number. It can be used to insert a needle from the past to the present to test the end to end of our understanding of the universe. It took phenomenally very detailed work, “said Dr. Lisia Verde, a cosmologist at ICREA and ICC-University of Barcelona, speaking about the work of the SHOES team.
The team measured 42 of the markers per mile on the Hubble supernova. Since they appear to explode at a rate of about one per year, Hubble, for all practical purposes, has registered as many supernovae as possible to measure the expansion of the universe. Rhys said: “We have a complete sample of all the supernovae available for the Hubble Space Telescope in the last 40 years.” Like the lyrics to the Kansas City song from the Oklahoma Broadway musical, “Hubble is so missing!”
Strange physics?
The rate of expansion of the universe is thought to be slower than what Hubble actually sees. By combining the Standard Cosmological Model of the Universe and measurements from the Planck mission of the European Space Agency (which monitors the relic space microwave background from 13.8.
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