Thursday, November 03, 2005

Edging Towards the Black

Astronomers are edging closer to seeing the dark hole at the center of the Milky Way galaxy.
Astronomers are reporting today that they have moved a notch closer to seeing the unseeable.

Using a worldwide array of radio telescopes to obtain the most detailed look yet at the center of the Milky Way, they said they had determined that the diameter of a mysterious fountain of energy there was less than half that of Earth's orbit about the Sun...

It also leaves astronomers on the verge of seeing the black hole itself as a small dark shadow ringed with light, in the blaze of radiation that marks the galaxy's center.

Until now, the existence of black holes - objects so dense that not even light can escape them- has been surmised by indirect measurements, say of stars or gas swirling in their grip. Seeing the black hole's shadow would require the ability to see about twice as much detail as can now be discerned...

"We're getting tantalizingly close to being able to see an unmistakable signature that would provide the first concrete proof of a supermassive black hole at a galaxy's center," [said] Shen Zhiqiang of the Shanghai Astronomical Observatory....

Astronomers have identified thousands of probable black holes. The candidates include objects billions of times as massive as the Sun at the centers of galaxies, where, it is theorized, gas and dust swirling toward their doom are heated and erupt with jets of X-rays and radio energy.

But the putative holes are too far away for astronomers to discern what would be their signature feature: a point of no return called the event horizon, in effect an edge of the observable universe, from which nothing can return. Instead, the evidence for black holes rests mainly on the inference that too much invisible mass resides in too small a space to be anything else...
Which is fascinating as it suggests a physical boundary to the universe, that it is not infinite in all directions. Although on the other side of the black, who knows what resides?
...The center of the Milky Way is about 26,000 light-years away, in the direction of Sagittarius. The new observations conclude that at the center of the galaxy an amount of invisible matter equal to the mass of four million Suns is crammed into a region no more than 90 million miles across. That small size, the radio astronomers said, eliminates the most likely alternative explanation of the fireworks at the galaxy's center: a cluster of stars. Such a dense cluster would collapse in 100 years.

Even more conclusive proof would come from the observation of the black hole's shadow, which would be about five times the size of the event horizon and appear about as big as a tennis ball on the Moon as seen from Earth...
Any Jewish mystics out there or kabbalistically educated physicists who want to opine on the relation of the kabbalistic theory of tsimtsum to black holes?

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