Ever since humans began looking at stars, the biggest question remains how big the universe is out there. It was Edwin Hubble, who in the 1920s showed that the universe was not fixed and was rather expanding. Nearly a century after his discovery, his namesake, the Hubble Space Telescope, has made a new prediction. The Hubble Space Telescope has reached a new milestone in its work to find out how quickly the universe is expanding – and it supports the idea that something strange is happening in our universe. The pursuit of the universe’s expansion rate 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 accelerating the universe’s expansion. In recent years, thanks to data from Hubble and other telescopes, astronomers found another twist: a discrepancy between the expansion rate as measured in the local universe compared to independent observations from right after the big bang, which predict a different expansion value.
Talk about #GalaxiesGalore!— Hubble (@NASAHubble) May 18, 2022
This sonification of the 2014 Hubble Ultra Deep Field plays a single note for each galaxy in the image. The later the note plays in this musical piece, the farther away the galaxy is!
Listen to more: https://t.co/D9OsucjCUP pic.twitter.com/9Xxno9Ybbg
The cause of this discrepancy remains a mystery. But Hubble data, encompassing a variety of cosmic objects that serve as distance markers, support the idea that something weird is going on, possibly involving brand new physics. Combined, these objects built a “cosmic distance ladder” across the universe and are essential to measuring the expansion rate of the universe, called the Hubble constant after Edwin Hubble. That value is critical to estimating the age of the universe and provides a basic test of our understanding of the universe.
In 2005 and again in 2009, the addition of powerful new cameras on board the Hubble telescope launched “Generation 2” of the Hubble constant research as teams set out to refine the value to an accuracy of just one percent. This was inaugurated by the SH0ES program. Several teams of astronomers using Hubble, including SH0ES, have converged on a Hubble constant value of 73 plus or minus 1 kilometer per second per megaparsec.
While other approaches have been used to investigate the Hubble constant question, different teams have come up with values close to the same number. The project was designed to bracket the universe by matching the precision of the Hubble constant inferred from studying the cosmic microwave background radiation left over from the dawn of the universe.
The team measured 42 of the supernova milepost markers with Hubble. Because they are seen exploding at a rate of about one per year, Hubble has, for all practical purposes, logged as many supernovae as possible for measuring the universe’s expansion.
The search for a precise measure of how fast space was expanding came when American astronomer Edwin Hubble that galaxies outside of ours appeared to be moving away from us – and doing so faster the further away from us they are. Scientists have been hunting for a better understanding of that expansion ever since. When the space telescope started gathering information about the universe’s expansion, however, it turned out to be quicker than models had predicted. Astronomers predict that it should be about 67.5 kilometers per second per megaparsec, give or take 0.5 – but observations show it is around 73.
There is only a one-in-a-million chance that astronomers have got it wrong. Instead, it suggests the universe’s evolution and expansion are more complicated than we had realized, and that there is more to learn about how the universe is changing.
Who was Edwin Hubble?
Edwin Hubble was born on the 20th of November in 1889. The name is beared by the Hubble space telescope. His work helped define our modern cosmology: our idea of the universe as a whole. He was a multi-talented man, with an interest in science he was an undergraduate from the University of Chicago. To keep his father’s wish he studied law. He was also an amateur heavyweight boxer.
Shortly before his death, Hubble became the first astronomer to use the newly completed, famous Hale Telescope at the Palomar Observatory near San Diego, California. At the time, the 200-inch (5.1-meter) was among the largest in the world. Hubble helped astronomers see that we live in an expanding universe, where every galaxy is moving away from every other. This discovery was known as Hubble’s law for many years. At its simplest, the law states that the more distant the galaxy, the faster it is moving away from us. This is at the heart of our modern cosmology. The entire universe – space, time, and matter – is thought to have been born in a Big Bang.
In the 1920s, Hubble was among the first to recognize that there is a universe of galaxies beyond the boundaries of our Milky Way. Edwin Hubble observed stars in a hazy patch of light that at the time was known as the Andromeda nebula. Hubble observed variable stars, those that change in brightness. He measured the period of how long a star took to dim and brighten. From the period of brightening, he calculated the star’s intrinsic brightness. From that, he could calculate the distance. That’s when he realized that the stars in this nebula were so far away that they couldn’t exist within our own galaxy. At the time, many astronomers believed that the Andromeda nebula was a forming solar system, within the Milky Way’s boundaries. Hubble showed that this patch of light was really a separate galaxy. Thanks to Hubble, we know it today as the Andromeda galaxy. It is the nearest large spiral galaxy beyond the Milky Way.
A galaxy in Andromeda:
The Andromeda galaxy is about 2.5 million light-years beyond our Milky Way. We also know that other galaxies extend around us in space for many billions of light-years. To people in the 1920s, though, this was a revelation. As soon as astronomers learned that spiral nebulae like the one in Andromeda are separate galaxies, the known universe got much bigger.
Is the huge Universe stationary or expanding or contracting?
The answer involved the light of galaxies as a whole. Astronomers observed shifts toward the red end of the spectrum in distant galaxies’ light. They interpreted this redshift as a sign that the galaxies are moving away from us. Hubble and his colleagues compared the distance estimates to other galaxies’ with their redshifts. On March 15, 1929 – Hubble published his observation that the farthest galaxies are moving away faster than the closest ones. This insight is initially known as Hubble’s Law.
When Hubble presented his evidence of the expansion of the universe, Einstein embraced the idea. He called his adherence to the old idea his “greatest blunder.” Einstein’s Theory of Relativity implied that the universe must either be expanding or contracting which he himself rejected further. He favored that the universe is stationary and existed always.
The observations have been going on since Hubble got into orbit, and they were enhanced in 2005 and again in 2009 after the addition of powerful new cameras onboard the Hubble telescope. Nobel Laureate Adam Riess of the Space Telescope Science Institute (STScI) and Johns Hopkins University led the scientific collaboration investigating the universe’s expansion rate called SH0ES or Supernova, H0, for the Equation of State of Dark Energy. Scientists are hopeful that the James Webb telescope will further refine these observations and give an even more precise calculation of the expansion rate.
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