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Making History: Karl Gebhardt

History Makers

University of Texas astrophysics professor Karl Gebhardt addresses some big issues in his work. Big, as in galactic. Most of his career has focused on understanding the role that black holes play in the formation of a galaxy. Now he is helping lead a new scientific revolution: the quest to understand dark energy, a mysterious force that makes up 70 percent of the matter and energy in the universe.

Scientist and UT Austin Professor Karl Gebhardt made history with a dark energy experiment that created the largest map of the universe.

Scientist and UT Austin Professor Karl Gebhardt is studying dark energy and how it affects the expansion of the universe.

Gravity: Do we have it all wrong?

Somehow, dark energy is defying what we think we know about gravity — instead of slowing down as it expands ever outward, the universe appears to be speeding up. Using the world’s third largest telescope at UT’s McDonald Observatory, Gebhardt and his collaborators will soon know more about this phenomenon.

Dark energy can be thought of as our ignorance of what’s going on in the universe, Gebhardt says. “We think we have an idea of how the universe is supposed to expand,” he says, but when the expansion rate is measured given those assumptions, things don’t add up. “It’s actually expanding faster than we think it should be. And that is what we call dark energy. What I always like to say is it’s only a phrase. Don’t get hung up on the word ‘dark,’ or on ‘energy.’ The solution of what it is may not be dark, and it may not be energy.” What it is, in other words, is an unanswered question.

The McDonald Observatory initiative, called HETDEX — the Hobby-Eberly Telescope Dark Energy Experiment — is the first major effort to answer that question. By revealing new details about the Big Bang, HETDEX will probe dark energy and tell us whether the laws of gravity are correct or if they need to be amended.

How you can help rewrite the laws of physics

So, what if Sir Isaac Newton was wrong? With your support, we can continue researching the origins of the universe to discover if the laws of physics should be updated. Your gift will help astronomers:

  • Study exploding stars
  • Map millions of galaxies
  • Probe conditions near the time of the big bang

The result of your support for scientific research? Scientists tweak their models of how the universe began, how it has aged, and how it will end. Help us make history and make your gift today.

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Related links:

Karl Gebhardt profile

HETDEX: Leading the Revolution

UT Department of Astronomy

UT McDonald Observatory

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