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UT Experiment Grapples With Essence of Gravity

Beset by the threat of natural disasters and potential funding difficulties, the Hobby-Eberly Telescope Dark Energy Experiment at the University of Texas' McDonald Observatory could turn gravity’s time-honored laws on their head.

By Michael Hoinski
Blue sky reflects in the primary mirror of the Hobby-Eberly Telescope at McDonald Observatory in this aerial view. The mirror is made of 91 individual segments. A dark instrument platform, which sits at the top of the telescope, partially obscures the mirror.

We have all experienced gravity, but even to the brightest minds in science, it remains largely a mystery. Gary J. Hill, an astronomer at the University of Texas at Austin, is trying to change that.

“We don’t know why there’s gravity,” said Hill, one of the lead astronomers on the Hobby-Eberly Telescope Dark Energy Experiment, or HETDEX, which could turn gravity’s time-honored laws on their head. “We have a pretty good theory of it. It may be that our observations could have a bearing on finally formulating why gravity exists.”

Hill has teamed with Karl Gebhardt, an astronomy professor at UT, on the $36 million project, which has prevailed despite the threat of natural disasters, potential lack of financing and all the kinks that can throw off a long-term project. The experiment’s goal is to analyze our understanding of how the universe is expanding — with ramifications on gravity, the Big Bang theory and the fate of the universe.

“Not only is the universe expanding, but it’s accelerating,” Gebhardt said. “And so that’s what we call dark energy — the existence of the acceleration. And that’s the huge thing that no one can explain.”

Granted, in a time of high unemployment, crazy gas prices and water shortages, studying the swelling of the universe might seem out of touch. But when asked about its importance, Steven Weinberg, a Nobel Prize-winning physicist at UT, said, “Do you really need a sermon on why settling questions about the fundamental laws of nature are worth pursuing?”

For Hill, 48, and Gebhardt, 46, even to be in position of rewriting the books is fortunate. The McDonald Observatory — where the dark-energy observations, made with the third-largest telescope in the world, are set to begin next spring after nearly 10 years of development — is about 425 miles west of Austin, in Fort Davis. In April, the Rock House Fire, which started 35 miles south of there, in Marfa, scorched the Davis Mountains surrounding the state-of-the-art observatory, putting it perilously close to going up in flames.

Mother Nature has not been the only threat. Lack of financing for an abstract experiment with little or no immediate pay-off has stymied several similar projects that sprang from the discovery of dark energy in 1998. Now, only a handful of those remain, and none have the proprietary will of HETDEX — a testament to the ego of the state of Texas.

Nearly a third of the money raised for HETDEX, which includes a one-of-its-kind $16 million spectrograph created by Hill called Virus (Visible Integral-Field Replicable Unit Spectrograph), came from private in-state sources. The largest donor, Harold Simmons, a Dallas investor and UT alumnus whom Forbes magazine ranked as the 55th-richest person in the United States, gave two gifts totaling $6.5 million. (Simmons’ family foundation is a major donor to The Texas Tribune.)

“I could see that figuring out the nature of dark energy would be of historic importance, not just in astronomy but for all science, and for all humankind,” Simmons said in an email. “As a proud Texan, I wanted a Texas-based, Texas-led project to be first.”

Meanwhile, broader debate has recently emerged over the role of academic research in state universities, with some conservatives calling for a greater emphasis on teaching to improve efficiency. But many in the higher education community have argued that the benefits of research extend beyond universities’ bottom lines.

“This is helping us train the next generation of engineers and leaders in these fields of technology,” Gebhardt said of HETDEX, which derives about a quarter of its financing from UT and a $6 million special biennial line item in the state budget. “And that’s important because we don’t have a lot of that in the country.”

The impact on education goes even deeper, Hill said, explaining: “Kids, when they’re 5 or 6 or 7, these are the ones who get interested in science through fields like paleontology and astronomy. These are exciting areas.”

Where the education system falls short, Hill added, “is failing to take that excitement and actually train them so they remain excited through college.”

The McDonald Observatory’s history also provides a valuable lesson in collaboration.

On a recent tour, Thomas Barnes, the observatory’s superintendent, said UT did not even have an astronomy department in 1926, when William Johnson McDonald, a banker from Paris, Texas, bequeathed his $1.1 million fortune to start an observatory. UT enlisted the University of Chicago to design and build the operation under the direction of Otto Struve, a Russian-born, fourth-generation astronomer who operated the McDonald Observatory for 30 years, ushering it into the UT-led era.

“Better a foreigner than a damn Yankee,” one of the UT regents at the time said of Struve’s appointment, according to Barnes.

And now the UT astronomy department has a chance to enhance its history.

“There will only be one time when we figure out what is in the universe, and then it gets placed in the textbooks,” Gebhardt said. “We are basically living through that time now.”

Michael Hoinski is a regular contributor to The New York Times and

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