Yet another black hole question....

[alokmohan]

Same post thrice.Plese delete two.

 

[alokmohan]

In univesrse it is the opposite of black hole.Matter spreads out and concentrated.It is example of white hole.

 

[serak_the_preparer]

<i>Not going to reply since my guess is as good as anyone elses just reading along.</i><br /><br />Some gentlemen at Princeton yesterday announced success in taking some of the guesswork out:<br /><br />Princeton physicists connect string theory with established physics by Chad Boutin (Princeton University)<br /><br />May 1, 2007<br /><br /><i>. . . The theory has been highly praised by some physicists for its potential to forge the long-sought link between gravity and the forces that dominate within the atomic nucleus. But the theory -- which posits that all subatomic particles are actually tiny "strings" that vibrate in different ways -- has also drawn criticism for being untestable in the laboratory, and perhaps impossible to connect with real-world phenomena. <br /><br />However, the Princeton researchers have found new mathematical evidence that some of string theory's predictions mesh closely with those of a well-respected body of physics called "gauge theory," which has been demonstrated to underlie the interactions among quarks and gluons....<br /><br />String theory, for all its mathematical beauty, once again seemed too difficult to test -- until Niklas Beisert, an assistant professor of physics at Princeton, published a paper in late October of last year containing an equation that turned out to be a crucial piece of the puzzle. <br /><br />"Beisert and his collaborators made an inspired guess based on sophisticated notions of gauge theory behavior," said Curtis Callan, the James S. McDonnell Distinguished University Professor of Physics at Princeton. "Their equation allowed Igor and his colleagues to work out the 'transition' between the two regimes. They demonstrated that it exactly matched string theory's predictions at the strong interaction limit. That was the hard part...."</i><br /><br />Exciting mathematics? This time around, yes. This stuff is all of a piece. The gra

 

[alokmohan]

Gauge theory is latest addition.

 

[alokmohan]

Spullberg says same thing thrice.What he means?He is worshipper of white hole?

 

[dragon04]

AN interesting question that I've always wondered about myself.<br /><br />If the laws of gravity as we understand them prohibit the escape of mass from even an 8 stellar mass BH, it seems intuitive to me that size truly wouldn't matter.<br /><br />Galaxies don't explode because billion solar mass central massive black holes somehow defy gravity, so how could any singularity, no matter how massive and dense achieve this, and even if they could, based on observation, when or how could they become "small enough" where gravity kicks back in and stops the process?<br /><br />I think this is a good argument for greater forces acting from outside of 4 dimensional space-time. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[alokmohan]

The rules of physics aruond singularity are not yet well known .Wheeler called it fierry marriage of quantum mechanics and gravity.

 

[serak_the_preparer]

<i>The possibility exists that other relics from the early universe may eventually be discovered.</i><br /><br />More on that:<br /><br />Is the evidence for 'alien' universes all around us? by Zeeya Merali (New Scientist)<br /><br />09 May 2007<br /><br /><i>. . . Yet when Alex Vilenkin of Tufts University in Medford, Massachusetts, and his colleagues recently calculated the probability of such lethal collisions </i>[between universes]<i>, they found it to be very low. Aguirre has now considered the chances of benign collisions that leave our universe more or less intact, such as when another universe partially infiltrates ours. If the cosmological parameters in the second universe are not too different from our own, such a collision would not necessarily destroy life, Aguirre says. Another possibility is that the wall of our universe could expand into another, destroying its inhabitants but leaving our universe unscathed.<br /><br />Aguirre and his colleagues Matthew Johnson and Assaf Shomer calculated the probability of such benign collisions and their observable repercussions (www.arxiv.org/abs/0704.3473). "What was surprising to me is not only that the signs would be there, but that they should be huge enough for us to observe," says Aguirre. What's more, such collisions could have occurred during the history of the universe, they found.<br /><br />Signs would be visible as large-scale anomalies in the distribution of hot and cold spots in the CMB. "I probably shouldn't speculate, but observational cosmologists have spotted signs of a strange alignment in the CMB that could be compatible with this picture," says Aguirre. This large-scale pattern seems to be aligned along what is often called the "axis of evil", though the finding remains controversial (New Scientist, 13 April, p 10).<br /><br />Carlo Contaldi, an expert on the CMB at Imperia</i>

 

[serak_the_preparer]

<i>The reason why we are wondering what will happen when we would near and go into a black hole, seems to be the 'magic' attributed to a singularity.</i><br /><br />True. Philip Ball tries to dispel some of the magic:<br /><br />How to survive in a black hole by Philip Ball (Nature)<br /><br />18 May 2007<br /><br /><i>. . . Falling into a black hole is a strange affair. Because the hole's gravity distorts space-time, a far-off observer watching an object crossing the event horizon sees time for that object appear to slow down — a clock falling into a black hole would appear, from the outside, to tick ever slower. At the horizon itself, time stops, and the object stays frozen there for the remaining lifetime of the Universe.<br /><br />But this isn't how things seem to the in-falling object itself. Indeed, if the black hole is big enough, nothing noticeable happens when a spaceship crosses its event horizon — you could stray inside without realizing. Yet once inside, nothing can save you from being crushed by the hole's gravity sooner or later.<br /><br />Clearly, an astronaut in that situation might prefer it to be later. For a supermassive black hole such as that thought to exist at the Galactic Centre, the survival time could be hours. To stretch it out for as long as possible, the astronaut might be tempted to turn on rocket thrusters and try to head outwards, away from the hole's fatal 'singularity' at the centre....<br /><br /></i>[Geraint Lewis]<i> adds that "even Einstein had a very hard time attempting to fathom just what is going on as things fall into a black hole."</i><br /><br />For the rest of the article, there's the link (which will work for awhile before expiring). The scientists cited in the article - Geraint Lewis and Juliana Kwan of the University of Sydney - debunk the myth that firing thrusters in a black hole is useless in slowing one's descent.