One of the mysteries of the universe has to do with the expansion of the universe. This is fundamental to understanding the evolution and end of the universe. Scientists now confirm that the universe is indeed expanding, but why is it expanding? Or what the true rate of its expansion is remains a question without a clear answer.
As for the expansion rate, scientists have many ways to measure it, but there are two widely accepted methods. It is the standard candle method and the standard ruler method
1. Standard Candle Method (Standard Candles) This method uses the Hubble Space Telescope to create the so-called “Cosmic Distance Ladder” It is a method used by astronomers to measure the relative distances of objects in the universe, depending on the object being observed. The reason it is called a staircase is because each step depends on the results of the previous step that was surveyed. What is used to measure relative distance is the light in the universe. This light comes from Cepheid variable stars and LA-type supernovae, and astronomers use brightness and scintillation at a fixed frequency as the basis for measurement. To calculate distances in space in this way, scientists estimate that our universe is expanding at a speed of about 73 kilometers per second per megaparsec, and (parsec) is an astronomical unit of measurement. To measure the vast distance between galaxies, one parsec is equal to 3.26 light-years, so 1 megaparsec equals 3.26 million light-years.) This means that for every 1 megaparsec of the universe's size, the universe is expanding at a rate of 73 kilometers per second.
2. Standard ruler method This method measures the expansion of the universe using signals from the early universe, namely the cosmic microwave background (CMB), the first light to shine through the universe. They occurred about 380,000 years after the Big Bang and another signal is Baryon Acoustic Oscillations (BAO), which are sound waves from the early universe. Using this method, scientists found an expansion rate of about 67 kilometers per second per megaparsec.
As you can see, the two measurement methods give inconsistent values for the expansion speed of the universe. No matter how many times scientists have estimated the expansion rate of the universe, these two methods have inconsistent results. This is called “Hubble tension” This will affect information about the age of the universe and how it evolved. This raises many questions: “Is Hubble's data collection accurate? Or do we have to evolve and look for new physics approaches? To further understand the expansion of the universe. Or are the results of these two methods for estimating the expansion of the universe the result of errors?”
But recently the SH0ES (SH0ES or Supernova H0 for dark energy equation of state) team has been searching for a new way to observe and estimate the expansion rate of the universe. With the Hubble Telescope and the James Webb Space Telescope working together, the results are accurate. And reduce errors, led by Adam Ries, a physicist from Johns Hopkins University, who won the Nobel Prize for co-inventing the theory that the expansion of the universe is accelerating. It is the result of a mysterious phenomenon now called “dark energy”
There has been a long-standing problem of measuring the light of Cepheid variable stars, and usually when scanning on the first rung of the ladder, there is no major problem. But as you explore deeper into the universe or if the survey moves further along the second step, the measurement accuracy will be lower. This is the result of light from stars merging together, causing interference in the measurements, and Hubble's images of Cepheid variable stars appear to be more clustered together. It interferes with nearby stars so that it is difficult to separate them, in addition to the fact that there may be dust that changes the accuracy of the measurement.
But Chu's team brought along the James Space Telescope. Webb joined the study. Because the James Webb Space Telescope is able to perform sharper surveys than Hubble at infrared wavelengths. This helps eliminate two major problems: 1. Being able to look through the dust and explore and 2. Ability to clearly separate variable stars from stars. The results help confirm the accuracy of Hubble's observations and data collection. There has been little expected movement in 34 years, according to the European Space Agency.
What matters now. Even with this new measurement method, scientists still cannot solve the problem. Hubble tension That it still has unequal values begs the question that there may be something woven into the fabric of space that we don't yet understand. As Adam Rhys said “Once we eliminate errors in measuring the expansion rate of the universe, we will find the truth about the universe. It is exciting to think that we might be wrong about the universe.
Scientists are now using Hubble's James Webb Camera to take definitive measurements that may reveal other possible ways the universe affects its expansion rate. In addition to measurement errors, the latest survey includes five galaxies hosting eight Type Ia supernovae, and a total of 1,000 Cephid variable star swarms, extending to NGC 5468, the most distant galaxy. It is located 130 million light-years from Earth, covering the entire range measured by Hubble, said Gagandeep Anand, co-author of the study and curator of the James Telescope. NASA's Webb and Hubble said this “represents the second end of the cosmic distance scale,” suggesting that… Hubble has pushed the limits of observation as far as possible. Which can make reliable measurements using current technologies.
Adam Rees added: “James Webb and Hubble have collaborated and are giving us even better results. We have now expanded the total range observed by Hubble. We have been able to rule out measurement error as a cause of Hubble jitter, and we have very high confidence.”
In summary That is, this research has devised a new way to measure the expansion rate of the universe using the standard candle method. Using the Hubble Telescope and the James Webb Space Telescope, it was possible to measure the exact distance of the Cepheid variable star and reach the end of the second step of the cosmic distance ladder, but the expansion rate of the universe's body still does not correspond to the value obtained using the standard ruler method. Therefore, researchers noticed that there may be structures in the universe that we humans do not understand or have not yet discovered, and we are currently using the Hubble and James telescopes. Webb takes the final measurements. We still can't say when we will get the answer. The numbers for the expansion rate of the universe may be different from what we previously knew.
It is considered another advance in our human cosmology. We may soon be able to solve the Hubble tensor problem, making it possible to know the true expansion rate of the universe. At the same time you may discover new structures woven throughout the universe. It is uncertain whether our original understanding of the universe was wrong. It may be necessary to renew our understanding of the universe. But above all, it will advance humanity. Because humans will push their abilities to the limits. In developing more advanced technology than before to find the answer that is still controversial and ambiguous.
The discovery was published in the February 6, 2024 issue of The Astrophysical Journal Letters.
Data source NASA, Futurism, space, Science Alert, European Space Agency
Image source NASA
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