09-08-2008, 07:43
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חבר מתאריך: 28.01.08
הודעות: 6,768
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Black hole wandering through our Solar System
Stellar-mass black holes travel through the Milky Way just like stars Consequently, they may collide with the Solar System or another planetary system in the galaxy, although the probability of this happening is very small. Significant gravitational interactions between the Sun and any other star in the Milky Way (including a black hole) are expected to occur approximately once every 1019 years.[64] For comparison, the Sun has an age of only 5 × 109 years, and is expected to become a red giant about 5 × 109 years from now, incinerating the surface of the Earth.[38] Hence it is extremely unlikely that a black hole will pass through the Solar System before the Sun exterminates life on Earth.
Micro black hole escaping from a particle accelerato
There is a theoretical possibility that a micro black hole might be created inside a particle accelerator.[65] Formation of black holes under these conditions (below the Planck energy) requires non-standard assumptions, such as large extra dimensions.
However, many particle collisions that naturally occur as the cosmic rays hit the edge of our atmosphere are often far more energetic than any collisions created by man. If micro black holes can be created by current or next-generation particle accelerators, they have probably been created by cosmic rays every day throughout most of Earth's history, i.e. for billions of years, evidently without earth-destroying effects. However, such natural micro black holes would be relativistic relative to earth, and should zip safely through our planet in 1/4 second or less at 99.99+% c. Collider produced micro black holes would be relatively "at rest" where they could become gravitationally bound, affording repeated opportunity to interact and grow larger, travelling at a tiny fraction of c, if Hawking Radiation is not real. This distinction between nature-made and man-made micro black holes has not yet been addressed in any of the safety studies on potential collider production of micro black holes.[citation needed]
If two protons at the Large Hadron Collider could merge to create a micro black hole, this black hole would be unstable, and would evaporate due to Hawking radiation before it had a chance to propagate. For a 14 TeV black hole (the center-of-mass energy at the Large Hadron Collider), the Hawking radiation formula indicates that it would evaporate in 10-100 seconds.
The European Organization for Nuclear Research (CERN) conducted a study assessing the risk of producing dangerous objects such as black holes at the Large Hadron Collider, and concluded that there is "no basis for any conceivable threat."[66] However, due to renewed concerns about both potential negative strangelet production, and LHC micro black holes that are "at rest" compared to natural micro black holes that are relativistic, CERN commissioned another study in 2007, with the results to be published in early 2008. Essentially, the concern is that due to their tiny size, a relativistic micro black hole would barely interact while traversing earth, being very similar to a neutrino in having a low cross-section for interaction, and therefore harmless. Conversely, the relatively slow speed of collider-produced micro black holes and their gravitational binding to earth would allow for repeated opportunity to interact with matter, eventually allowing such micro black hole to grow larger. Those speculative scenarios also require that theoretical Hawking Radiation is not real.
נערך לאחרונה ע"י -TsAcHi - בתאריך 09-08-2008 בשעה 08:08.
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