This is cool. Scientists have developed a mathematical framework that should allow them to test a 5-dimensional theory of gravity. Their theory predicts the existence of tiny black holes in our solar system that Einstein's theory wouldn't allow. We'll hear more in a few years.
3 hours of related info. Nova program about string theory, based on Brian Greene's The Elegant Universe.
4 comments:
This does seem quite interesting, as it would would provide the first speck of evidence that string theory might actually hold water.
I'm somewhat skeptical that GLAST (the new telescope) would be able to find and detect gravitational lensing by a black hole the mass of a very small asteroid, since it is the mass of the black hole that matters, not the "size." This means that the degree of gravitational lensing on incoming EM is about equal to that caused by a small asteroid's mass, which is very small in magnitude. Though, the higher energy a photon of EM, the more it is able to bend, gamma rays are very energetic.
I don't know what to tell you, other than "I doubt it."
For something the mass of an asteroid to be a black hole, it would have to be super-small. Wouldn't the tiny size curve space a lot more severely than an asteroid? Then you'd just need to find a gamma ray the passed through the tiny but severe distortion.
Or am I way off?
Black hoels are points, so they do not have radius or "size" in a sense. Their mass determines the their gravitational strength as well as their event horizon, or at what point beyond the center of the black hole the escape velocity equals the speed of light.
As most understand it, black holes do not form for any mass less than 1.44 solar masses; this is called the Chandrasekhar limit (for whom the Chandra X-ray telescope is named).
String theory predicts these smaller black holes, perhaps as a function of the extra spatial dimension, such as this asteroid-mass one they're looking for.
Gravitational lenses are not easy to detect, and usually require massive objects like supermassive black holes, quasars, etc. On a smaller scale, one experiment was done using the sun as a gravitational lens, which worked.
The mass of a tiny asteroid is quite tiny, and it's gravitational force is not particularly strong even when compressed to a point. Then again, I am thinking in relativistic mechanics, not string theory, so perhaps my estimations are off.
Albeit, I'm still skeptical.
Even using Einstein's framework (and adding that it would allow black holes with the mass of an asteroid), wouldn't the distortion of spatial fabric be different for a point-sized black hole and an asteroid of the same mass?
A crude analogy I can think of is imagine 2 swimming pools that hold the same volume of water. The first is 5 feet deep and fairly small, and the other is only 6 inches deep, but covers 10X more area. Then the experiment is to have someone stand in each pool and see who gets more wet.
Right?
Also, under string theory black holes are definitely not points. But I'm not sure if black holes of varying masses have different sizes under string theory.
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