Light bending by a black hole may offer proof of extra dimensions

Nov 18, 2010

(PhysOrg.com) -- Researchers at the University of Pennsylvania report that a new test for measuring the ability of gravity to bend light seen from distant stars around large objects like black holes may offer proof of the existence of extra dimensions in the universe.

Most of the work by astrophysicists studying the effects of , or light bending, relates to and galaxy clusters. New research from Penn makes use of the believed to exist at the center of the galaxy.

The analysis was carried out by Amitai Y. Bin-Nun, a theoretical astrophysics and cosmology graduate student at Penn, with guidance from Justin Khoury, assistant professor, and Ravi K. Sheth, professor, both in the Physics and Astronomy Department in Penn’s School of Arts and Sciences. The article appears in the journal Physical Review D.

“We found that, if our universe is described by a theory incorporating extra dimensions, light near the black hole at the center of our galaxy may appear brighter than it would if we live in a universe without extra dimensions,” Bin-Nun said. “Detecting images at the brighter intensity would represent evidence of and would be an incredibly important development.”

Bin-Nun studied the effect of gravitational lensing on the stars orbiting Sagittarius A*, or Sgr A*, a radio source in the center of the Milky Way. Sgr A* was chosen because it hosts the supermassive black hole hypothesized to exist at the center of the Milky Way. The strong gravitational pull of the black hole distorts the light from Sgr A* before it reaches Earth, creating the illusion of multiple images of the same star.

Bin-Nun simulated the orbits of stars near the black hole and treated each star as a source lensed by the black hole, solving for the location and brightness of the “secondary” image which appears near the black hole. For each individual star, Bin-Nun found that the brightness of the secondary image would change over time and would peak in brightness when the star is nearly aligned with Sgr A*.

Next, he repeated the lensing analysis assuming the black hole was described by a metric coming from the theoretical Randall-Sundrum II braneworld scenario, which prescribes an extra fifth dimension. If that description of the black hole is correct, then the seconday image of the star S2 will be up to 44 percent brighter in early 2018 when it reaches its peak brightness, providing evidence for the presence of a fifth dimension where gravity is severely diluted. If not, then the four dimensional description of the black hole should be seen as more accurate.

Even if the exact universe is not five dimensional, or this analysis breaks down at other points, “we have shown alternative gravity theories have the possibility of creating a large gravitational lensing effect and we should look into lensing as a test for gravity theories,” Bin-Nun said.

The findings come with several caveats.

Certain assumptions on the form of the black hole were made as the shape of space around a five dimensional black hole is not known. Researchers did not take into account the spin of the black hole, which confounds the analysis. It’s also highly probable that, because the image is so close to the black hole and resolution of available ground-based telescopes are limited, the light from larger, nearby objects could obscure the image of the star, meaning observers won’t be able to isolate the effects of this particular iamge.

“These findings illustrate how the opportunities provided by the Penn physics Ph.D. program and its new Center for Particle Cosmology allow its students to make important contributions at the cutting edge of discovery,” Sheth said.

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User comments : 12

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Glenn_Spiczak
not rated yet Nov 18, 2010
What's the effect of an extra six (or seven) compactified dimensions? Is the effect proportional to the number or to the size of the extra dimensions?
Modernmystic
1 / 5 (1) Nov 18, 2010
What's the effect of an extra six (or seven) compactified dimensions? Is the effect proportional to the number or to the size of the extra dimensions?


I could be wrong Glen, but I think (for the moment at least) it's relevancy would mainly be tied to theroetical and acedemic issues. Such as since we see "x" dimensions of space this theory is not ruled out while that one over there is...
KwasniczJ
1 / 5 (9) Nov 18, 2010
Light bending itself is actually a manifestation of extradimensions - strictly 3D space is transparent and perfectly flat.
jdbertron
3 / 5 (2) Nov 18, 2010
Link to the article please.
frajo
1 / 5 (1) Nov 18, 2010
What's the effect of an extra six (or seven) compactified dimensions? Is the effect proportional to the number or to the size of the extra dimensions?
Their calculations are based on the RS2 model which has ("only") 5 dimensions.
KwasniczJ
1 / 5 (9) Nov 18, 2010
IMO as the qualitative evidence of fourth dimension can serve the fact, the remote image of single star fragments into odd number of images after the gravitational lens. As the qualitative evidence of fifth dimension would serve the situation, when each of images separated after the lens would split into group of another ones in fractal way.

http://www.kk.org...ring.jpg
am_Unition
not rated yet Nov 18, 2010
This is an excellent demonstration of scientific reasoning by Bin-Nun... Science begs us to find opportunities to pit different theoretically possible models against each other to find out which is the correct (or at least the more likely to be correct) reality.
KwasniczJ
1 / 5 (5) Nov 19, 2010
..this is an excellent demonstration of scientific reasoning by Bin-Nun...
Here are many models of dark matter, for example. If the gravitational lensing will be larger, then the general relativity predict, how Bin-Nun can be sure, it's manifestation of extradimensions - and not the dark matter, for example?
VK1
1 / 5 (5) Nov 19, 2010
@Glenn_Spiczak

The effect of an extradimension is that the space you see as empty is actually occupied and yet all of your senses that are tuned to interpret the space are unable to detect the occupant. You cannot see it smell it hear it taste it or touch it.

The singularity event horizon (blackhole shwarzchild sphere) can be viewed as an extradimensional portal (all information on the inside of the sphere is isolated from the 4D space-time outside of the sphere). We cannot know any of physical properties of the blackhole, it is dimensionally separated from our reality, we can only measure its influence on surrounding space. The blackhole sits in superposition, it is both there (we can witness its influence) and not there (we cannot see it).

@frajo
4D+6D=string, 4D+7D=M-theory/I believe that's what Glenn was implying.
genastropsychicallst
1 / 5 (4) Nov 19, 2010
Fermion (up)z subattomair warper (down)z organs Z twistor h-boson, Albert.
vidyunmaya
1 / 5 (3) Nov 20, 2010
SUB: LIGHT BEND PRINCIPLE
Plasma occupies the shape of the body
Universal Plasma Energy Model-1991-ICOPS- my paper.
Here I indicated Spirals and more phenomena.
Light bend principle- I put this question to a distinguished Nobel Laureate at Hyderabad-2007.He did not appreciate my quest. I suggested even Van Allen Belts !
How one grows against gravity if one does not understand the Light-Interactions on the Human Plane ?
Cosmology Vedas Interlinks provides next dimensional Science
Vidyardhi Nanduri
Tuxford
1.8 / 5 (5) Nov 20, 2010
Or, instead of concocting wild theory about extra dimensions, the data might provide direct evidence of genic energy production inside stars (photon blue-shifting predicted by LaViolette), in nonlinear proportion to the local gravity field. Luminosity would be expected to increase as a star orbits closer to the mother star at the galactic center, being closer to the intense gravity of the central object. Remember the Pioneer Effect! Sometimes the simple explanation is the right explanation. Or, be happy, and just remain confused.