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# The Mystery of the Universe: Exploring the Expansion Rate with Hubble and James Webb Telescopes

One of the mysteries of the universe It is about 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 its true rate of expansion is remains a question with no clear answer.

For the rate of expansion Scientists have many methods for measuring it, but two are widely accepted. is the standard candle method and standard ruler method

1. Standard Candle Method (Standard Candles) This method uses the Hubble Space Telescope to create what is called a “Cosmic Distance Ladder” It is a method that astronomers use to measure the relative distances of objects in the universe, depending on the object being observed. The reason why it is called a staircase Because each step depends on the results of the previous step that has been surveyed. What is used to measure relative distance is The light that exists in the universe This light comes from Cepheid variable stars and LA-type supernovae, and astronomers use the brightness and flickering of light at a constant frequency as a basis for measuring it. Using this method to calculate distances in space, scientists estimate that our universe is expanding at a speed of about 73 kilometers per second per megaparsec. (Parsec) is an astronomical unit of measurement. To measure the vast distance between galaxies, 1 parsec is 3.26 light years, so 1 megaparsec is 3.26 million light years.) This means that for every 1 megaparsec of the volume of the universe, the universe expands at a rate of 73 kilometers every second.

2. Standard Rulers Method This method measures the expansion of the universe using signals from the early universe, namely the Cosmic Microwave Background (CMB) radiation, which is the first light that shines through the universe. Occurred approximately 380,000 years after the Big Bang (Big Bang) and another signal is the sound vibration of Baryon (Baryon Acoustic Oscillations: BAO), which is 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 rate of expansion of the universe, these two methods have inconsistent results. This is called “Hubble Tension” This will affect information about how old the universe is and how it has evolved. That raises many questions: “Is Hubble’s data collection accurate? Or do we have to develop and look for new physics approaches? To further understand the expansion of the universe. Or are the results of these two methods of estimating the expansion of the universe due to errors?”

But recently the SH0ES (SH0ES or Supernova H0 for the Equation of State of Dark Energy) team has been looking for a new way to monitor and estimate the rate of expansion of the universe. Using the Hubble Telescope and the James Webb Space Telescope working together, the results are accurate. and reduce errors, led by Adam Riess, 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 that is now called “Dark Energy”

For measuring the light of Cepheid variable stars, there has been a long-standing problem. Normally, when surveying on the first step of the staircase, there is not much of a problem. But when you explore deeper into the universe or the survey moves further along the second step, the measurement accuracy will be less. That’s a result of the light from the stars merging together, causing interference with the measurement. Hubble images of Cephid variable stars appear to cluster together more. and overlaps with nearby stars Until it is difficult to separate them. In addition, there may be dust that is a variable in the measurement accuracy.

But the Chus team brought the James Space Telescope. Webb joined in the study. Because of the James Space Telescope Webb is able to survey sharper than Hubble in infrared wavelengths. This helps eliminate two main problems: 1. being able to look through the dust and explore and 2. being able to clearly separate variable stars from stars. And the results help confirm that Hubble’s observations and data collection were accurate. There has been little expected movement for 34 years, according to the European Space Agency.

The important thing is now. Even with this new measurement method But scientists still can’t solve the problem. Hubble Tension that still have unequal values It begs the question that there might be something woven into the fabric of space that we don’t yet understand. Like Adam Rees said “Once errors in the measurement of the universe’s expansion rate are eliminated, We will find the reality of the universe. And it’s exciting to think that we might be wrong about the universe.”

Scientists are now using the James camera Webb and Hubble combined to take Definitive Measurements that may reveal other possible ways the universe is influencing its expansion rate. In addition to measurement errors The latest survey includes five galaxies that host eight Type Ia supernovae, a total of 1,000 Cephid variable star swarms, and extends to NGC 5468, the most distant galaxy. Cepheid was measured. Located 130 million light-years from Earth, it covers the entire range measured by Hubble. Gagandeep Anand, co-author of the study and curator of the James Telescope, said: Webb and Hubble for NASA said it “marked the second end of the cosmic distance ladder,” suggesting that Hubble had pushed the boundaries of observation as far as possible. which can make reliable measurements using existing techniques.

Adam Reese added: “The collaboration of James Webb and Hubble Giving us better results Now we’ve expanded the total range Hubble observed. We were able to rule out measurement error as the cause of the Hubble Tension, and we have very high confidence.”

In summary That is, this research has devised a new way to measure the rate of expansion of the universe using the standard candle method. By using the Hubble Telescope and the James Webb Space Telescope, it was possible to measure the precise distance of the Cephid variable star and reach the end of the second step of the cosmic distance ladder. But the expansion rate The body of the universe It still doesn’t correspond to the value obtained using the standard ruler method. Therefore, the researchers noted that There may be structures in the universe that we humans don’t yet understand or have yet to discover. Right now we’re using the Hubble and James telescopes. Webb takes final measurements. And we still can’t say when we’ll get the answer. The numbers for the expansion rate of the universe may be different from what we previously knew.

It is considered another advancement in our human cosmology. Soon we may be able to solve the problem of Hubble Tension, making it possible to know the true expansion rate of the universe. At the same time may discover new structures woven throughout the universe It is uncertain if our original understanding of the universe was wrong. It may be necessary to renew our understanding of the universe. But above all, they will lead to the progress of humanity. Because humans will push their abilities to the limit. in developing technology that is more advanced than before To find the answer that is still debated and mysterious.

The discovery is published in the February 6, 2024 issue of The Astrophysical Journal Letters.

Data source NASA, Futurism, Space, ScienceAlert, ESA

Image source NASA

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