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The mystery of our Universe


Wait long enough to start saying that the universe is big when we look in both directions; the most visible region in the universe is estimated to be 46 billion light-years away. It has a diameter of 540.6 billion miles (or 54, followed by 22 zeros). However, that is actually our best guess — no one knows exactly how big the world is.


This is because we can only see light (or, more accurately, microwave radiation from the Big bang) that has passed since the beginning of the universe. The universe has been expanding since it exploded about 13.8 billion years ago. However, since we do not know the exact age of the universe, it is hard to determine how far beyond the limits we see.


However, one feature astronomers are trying to use to help them do so is a number called the Hubble Constant.


“This is a measure of the current rate of universe expansion,” says Wendy Friedman, an astrophysicist at the University of Chicago. “The Hubble constant determines the size of the universe including its size and age.


It helps to think of the world as if a balloon has exploded. When stars and galaxies move as dots on the surface of balloons, the faster they move between them, the greater the distance between them. From our point of view, that means that the farther a galaxy is from us, the faster it retreats.

Unfortunately, whatever astronomers measure this number; they seem to ignore predictions based on our understanding of the universe. One way to measure, directly gives us some value, while the other direct measurement method based on our understanding of other parameters of the universe, which represents something different. Either the measurements are wrong or we think our world is going down.


However, scientists now believe they are close to the answer, thanks in large part to new experiments and observations aimed at figuring out Hubble’s constant.


“As cosmologists, we face an engineering challenge: how do we measure this number as accurately and accurately as possible?” says Princeton University astronomer Rachel Beaton. To meet this challenge, he says, it is not only necessary to obtain data to measure it, but also compare the results as much as possible. “From my perspective as a scientist, it’s more like joining a puzzle than an Agatha Christie-style puzzle.


In 1929, astronomers first measured the Hubble constant, called Edwin Hubble, at speeds of 500 kilometers (km/s/mpc) or 310 miles per hour per mega per second. This value means that for every second megaparsec (a unit 3.26 million light-years away), you look farther than Earth, and you see galaxies 500 kilometers per second (310 miles per second) faster than that megaparsec.

Since Hubble first estimated the speed of the universe’s expansion, this number has revised repeatedly. Today’s estimate is between 67 and 74 km/s/Mpc (42-46 mph/s/Mpc).

Part of the issue is that the Hubble constant may vary depending on how it is measured.


Most descriptions of Hubble’s constant differences say there are two ways to measure its value: one by observing how fast nearby galaxies leave us, and the other with the Cosmic Microwave Background (WBC), the first light that escaped after the Big Bang.


We can still see this light today, but as distant parts of the universe approach us, light extends into the radio waves. These radio signals were first discovered by chance in the 1960s, which could give us an early understanding of what the universe looks like.


Two competing forces – gravity pull and external radiation drift – caused a cosmic tug of war with the universe at an early age, causing interference and still seeing small temperature differences at the bottom of the microwave cosmic.


With these disturbances, you can measure the extent of the universe’s expansion shortly after the Big Bang, which can then applied to standard cosmological models to infer the current rate of expansion. This standard model is one of our best explanations of how the world starts, what it’s made of, and what we see around us today.


Problem Facing

However, there is a problem. Astronomers got a different number when they tried to measure the Hubble constant by looking at how far close galaxies are from us.


“If the (standard) model is correct, then you can imagine these two values: the values you measure locally today, and the values you infer from the initial observations, will agree,” Friedman says.


When the European Space Agency’s (ESA) Plank satellite measured the differences in CMB, first in 2014 and then again in 2018, the Hubble constant was worth 67.4 kilometers (41.9 miles)/s/Mpc. However, that is about 9 percent less than astronomers like Friedman measured when they looked at nearby galaxies.


CMB will further measure in 2020 using the Atacama Cosmology Telescope, which relates to plank data. “This helps to rule out the possibility that Mr. Trump has systemic problems at various sources,” Beaton says, “if the CMB measurements are correct, leave one of two possibilities: either the technology that uses light from nearby galaxies is turned off or the standard cosmological model needs to be changed.


Friedman and his colleagues used techniques that used a particular type of star called the hofoid variable. About 100 years ago, an astronomer named Henrietta Levitt discovered these stars, whose glow changes and becomes weaker and brighter in a few days or weeks. Levitt discovered that the brighter the star, the longer it darkens, then darkens, and then lights up again. Astronomers can now accurately determine the brightness of stars by studying the brightness of these pulses. By measuring how bright we see ourselves on Earth and seeing that dim light is a function of distance, it provides an accurate way to measure the distance of stars. (Read more about how Henrietta Levitt changed the way we view the world.)


Freedman and his team were the first to measure the Hubble telescope’s constants using the white variable in a neighboring galaxy. They measured 72 kilometers (45 miles)/s/Mpc in 2001.


Since then the value of studying native galaxies has floated in the same spot. Another team used the same type of star from the Hubble Space Telescope to reach 74 kilometers (46 miles)/s/Mpc in 2019. Just a few months later, another group of astrophysicists used a different technique that included storied light to gain a value of 73 kilometers (45 miles)/s/mpc.


If these measurements are correct, they suggest that the universe may expand faster than the standard cosmological model allows. This could mean that the model – and our best efforts to describe the basic nature of the world – needs updating. For now, the answer is unclear, but if you do, the consequences could be profound.


“It probably tells us that we think our standard model has missed something,” Freedman says, “We still don’t know why it happened, but it’s an opportunity to explore.


If the standard model is wrong, it may mean that the model of what our universe is shaping, the relative amount of spikes or “normal” matter, dark matter, dark energy, and radiation, is not entirely true. If the world expands faster than we think do, it could be much younger than the 13.8 billion years accepted now.

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