Thursday, March 01, 2007

Dialogues of Eide

A high-energy proton (yellow line) flung into a lower-energy proton in the hydrogen gas cloud. The green arrow represents the high-energy gamma ray that results from the proton collision. -Artwork by Sarah Ballantyne

In 2004 scientists were startled when they discovered that the center of our galaxy is emitting gamma rays.

Astrophysicists at The University of Arizona, Los Alamos National Laboratory and the University of Adelaide (Australia) have discovered a mechanism that might produce these high-energy gamma rays. The black hole at the center of our Milky Way could be working like a cosmic particle accelerator, revving up protons that smash at incredible speeds into lower energy protons and creating high-energy gamma rays, they report.

When complete, the Large Hadron Collider in Switzerland will be able to accelerate protons to seven trillion electronvolts. Our galaxy's black hole whips protons to energies as much as 100 trillion electronvolts, according to the team's new study. That's all the more impressive because "Our black hole is pretty inactive compared to massive black holes sitting in other galaxies," Ballantyne noted.

Even though the protons move close to the speed of light, their motion is so random that it takes several thousand years for the particles to travel beyond 10 light years of the black hole. After the high-energy protons escape the black hole environment, they fly off into the interstellar medium, where they collide with low-energy protons (hydrogen gas) in a smash-up so energetic that particles called 'pions' form. These particles of matter quickly decay into high-energy gamma rays that, like other radiation, travel in all directions.

"Ironically, even though our galaxy's central black hole does not itself abundantly eject hyper-relativistic plasma into the surrounding medium, this discovery may indirectly explain how the most powerful black holes in the universe, including quasars, produce their enormous jets extending over intergalactic proportions. The same particle slinging almost certainly occurs in all black-hole systems, though with much greater power earlier in the universe," Melia said.

A Particle Accelerator at Galactic Center? from Centauri Dreams
Milky Way Black Hole Is a Natural Particle Accelerator from Universe Today
Milky Way Black Hole May Be A Colossal 'Particle Accelerator' from Science Daily

Searching for Extra Dimensions
Possible extra-dimensional effect observable at collides.
A graviton leaves our 3-dimensional world for a short moment of time, just to come back and decay into a pair of photons.

The search for extra dimensions is not over yet. In fact, it has only just started. We are looking for the effects of extra dimensions in collisions that produce different types of particles, such as quarks. We are also looking for events where gravitons are produced in the collisions and then leave our three-dimensional world, possibly travelling off into one of the other dimensions. This would cause an apparent non-conservation of energy from the point of view of our three dimensional world.

We very well might see them in the next generation collider.
The LHC, that has been built at CERN (near Geneva, Switzerland) will allow us to ultimately probe the theory of large extra dimensions and either find them or show that the idea is actually wrong. But we will have to wait a little longer, before we learn that.

Where are my keys - Searching for Extra Dimensions
from Plato @ Dialogues of Eide.


In physics, a wormhole is a hypothetical topological feature of spacetime that is essentially a 'shortcut' through space and time. A wormhole has at least two mouths which are connected to a single throat. If the wormhole is traversable, matter can 'travel' from one mouth to the other by passing through the throat. While there is no observational evidence for wormholes, spacetimes containing wormholes are known to be valid solutions in general relativity.

I am inclined to 'believe' there is an arrow of Time.
That we cannot rewind Time (like on film, video or DVD) and, it would be peculiar to see people and cars moving backwards or rain pouring skyward.

We probably cannot 'travel' back in Time, after all even if we could travel at the speed of light and lived for a 163,000 years - it is unlikely that Supernova 1987A would have stood still waiting for us. We would still arrive there in 163,000 years Time or 326,000 years after the event took place. (unless there are shortcuts)
Evaporating micro-black-holes from Bee @ Backreaction.
The Principle of finite imagination-ii by B @ Backreaction.
LHC detector performs first test of fundamental forces by JoAnne.

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