Dark energy ut astronomers take us closer to understanding the greatest mystery in physics the daily texan que gases componen el aire y su porcentaje


Modern science understands a lot about the universe. Astronomers know how planets and stars move from Newton’s laws, and physicists understand how gravity works from Einstein’s theory of relativity. But in 1929, astronomer Edwin Hubble discovered that the universe expands at an increasing rate, something no modern theory can explain.

Dark energy is a term astronomers use to refer to the mechanism behind the continual expansion of the universe. They don’t know exactly what causes it. It could be energy associated with empty space, according to Gebhardt. It could be that our laws of gravity are wrong or that dark matter adds extra mass to galaxies.

“Dark energy has to do with our gross misunderstanding of the way the universe is expanding,” Gebhardt said. “It may not be dark, and it may not be energy. That is the term we use to represent our ignorance. It is a placeholder for what’s going on.”

As the space between the Milky Way galaxy and distant galaxies grows due to expansion, the light that reaches Earth gets stretched out. Yellow light turns orange, purple turns blue. Essentially, the colors are shifted toward the red side of the color spectrum. By measuring the redshift, astronomers can measure the expansion.

“(We are) trying to explore these huge mysteries,” Gebhardt said. “That is one of the biggest mysteries out there. Why is the universe expanding the way it is? What is dark energy? (Astronomers) go after the most fundamental questions there are. Where does matter come from? Where does the universe come from? Why does gravity work?”

Systems engineer Jim Fowler works at HET. Fowler is part of a team of electrical engineers, mechanics, programmers and software engineers that ensures that the telescope remains operational. They handle the dirty work to make sure the team of scientists working on the dark energy project get the data they need to measure expansion.

His team worked hard to install Visible Integral-Field Replicable Unit Spectrographs, or VIRUS instruments. These form an array of instruments that collect spectral data from the light of distant galaxies in order to measure their position and velocity.

Light bounces off the telescope’s mirror and enters fiber cables. These cables feed the data into spectrographs located in black casings on either side of the mirror. The spectrographs reduce raw information, the wavelengths of light from every point in the sky, from the cables into a usable spectral data.

Research scientists use this data to measure the relative positions and velocities of faint, ancient galaxies. The fainter and further the light, the older the galaxy. If something is ten billion light years away, that means the light comes from a galaxy that is ten billion years old.

“We want to measure the expansion rate of the universe 10 billion years ago and compare it to the rate 4 billion years ago. The difference will allow us to better understand the physics behind it,” Gebhardt said. “That’s the fundamentals of HETDEX.”

“We are trying to find specific points in the data where there are star-forming galaxies,” Cooper said. “They are easy to spot, and we know the wavelengths well. So it’s easy to measure the redshift. That redshift can be translated to distances.”

The team needs millions of data points to produce a full map. Data scientists have to come up with ways to isolate spectral data that correlates to these star-forming galaxies. Basically, they need the computer to do what a person couldn’t and observe millions of galaxies and determine if they are useful.

“We are going to build the largest spectrograph that takes largest amount of data by a factor of 100,” said Gebhardt. “We’re taking one of the largest surveys in terms of time. And we’re using one of the most powerful computers (at the Texas Advanced Computing Center) on the planet. All those things separate are pretty profound, when you put them together it is kind of insane.”