Could gravitational lensing provide evidence for extra dimensions in the universe?

[Jim__]

At least one physicist thinks so:

In Einstein's theory, warped spacetime even affects light. When light from a star passes near a galaxy, for example, its path bends, changing where the star appears in the sky—the so-called gravitational lensing effect. If a star is just behind a gravitational lens such as a black hole, the effect can produce multiple images of a star or even a so-called Einstein ring that encircles the lens. Just like a telescope does, gravitational lensing also makes stars appear larger and hence brighter.

Now, physicist Amitai Bin-Nun of the University of Pennsylvania argues that gravitational lensing around Sagittarius A*, the supermassive black hole thought to be at the center of the Milky Way, might provide a way to search for extra dimensions. In one version of the extra-dimensions scenario, gravity is much stronger near the black hole than it would be without the extra dimensions, so that images of the stars appear larger and brighter than they otherwise would. Bin-Nun used numerical simulations to show that, in a world with extra dimensions compared with one without, a star known as S2 could be as much as 44% brighter when it reaches its peak brightness in 2018. If S2 were that bright, it could be evidence for extra dimensions or at least evidence that our understanding of gravity should be modified.

Bin-Nun says that the approach, published in Physical Review D, could be a good way to probe black hole properties, but he acknowledges practical and theoretical concerns. Using gravitational lensing to search for extra dimensions "depends on a telescope being able to see a very faint object" at the galactic center, he says, which may be impractical given current technology. Still, if astrophysicists observed the brightness Bin-Nun predicts, it could be a sign that some of those extra dimensions are coiled loosely enough to have a detectable effect.

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[Vincardog]

1. COOL K&R

[mdmc]

2. r

[somone]

3. They're still playing with string theory?

We're having enough problems with 4 dimensions.

[laconicsax]

4. Oh yeah. Here's a summary of the advances that have been made recently.

[somone]

5. 40 years and still not one verifiable prediction

but hundreds of people got tenure. Such a freakin' cult.

[laconicsax]

6. Now, now...