Black holes are known to gobble up everything around them, but the knowledge they share is changing research in fields besides astronomy.
Several Penn State programs, like the Chandra X-ray Observatory and the Swift Gamma-Ray Burst Explorer satellite, already study the physical aspects of black holes, which remain largely a mystery to astronomers. Researchers are also interested, however, in the theoretical and practical uses of studying these phenomena.
"Are black holes exactly what we think they are?" said Akhlesh Lakhtakia, professor of engineering science and mechanics. "An understanding of black holes could bring about a better understanding of current physics or a completely new physics."
The gravity around a rotating black hole acts in a way that is similar to material that has a negative phase velocity (NPV), he said.
This material, or a strong gravitational field in a vacuum, causes a beam of light to be refracted differently than if the beam were passing through a material with a positive index of refraction, like water, Lakhtakia said.
When a beam of light hits water, it bends downward slightly. However, when a beam passed through the NPV material, it will bend down but also in the opposite direction, he added.
Black holes allow researchers to study this concept, called negative refraction. This could bring about a new design of optical lenses that are virtually distortion-free, Lakhtakia said.
However, this idea of negative refraction adds uncertainty to our understanding of the night sky, he said.
Penn State's Institute for Gravitational Physics and Geometry (IGPG) works on projects in three different fields involving black holes, one of which is fundamental physics.
In this area, the IGPG works outside of EinsteinĂRs constraints and makes theoretical challenges that could extend or even change what is known about physics, said Abhay Ashtekar, professor of physics and director of the IGPG.
The theories posed by researchers that are based on known physics are then passed on to astrophysicists and astronomers to better guide their observations, Ashtekar said.
For example, the information-loss paradox questions whether things that enter a black hole can be recovered. Currently, the general belief is that the information is lost, Ashtekar said, but a few researchers believe it can be recovered.
The IGPG is also involved with gravitational wave research, with black holes as the source. Gravitational waves are disturbances in spacetime caused by the motion of matter.
To study these huge waves, the Laser Interferometer Gravitational-Wave Observatory uses three satellites to detect the waves, which have incredibly long wavelengths, Ashtekar said.
Other satellites Penn State is involved with are focusing on studying black holes at much shorter wavelengths. The Chandra X-ray Observatory records detailed images of X-rays given off by the accretion disk around a black hole, said Niel Brandt, professor of astronomy.
The observatory is able to study these emissions from distant galaxies because X-rays are very penetrating and are able to travel through the dust, allowing researchers to view images that would otherwise be obscured, Brandt said.
Observers therefore are able to learn how black holes develop, he said.
A black hole has still not been directly viewed, so researchers can't be exactly sure what they are, Lakhtakia said.
"It's disconcerting to realize that our understanding of the universe could be mucked up," he said.
