White Hole: the opposite of a black hole.

Since a black hole is a region of space from which nothing can escape, the time-reversed version of a black hole is a region of space into which nothing can fall. In fact, just as a black hole can only suck things in, a white hole can only spit things out.

White holes are a perfectly valid mathematical solution to the equations of general relativity, but that doesn't mean that they actually exist in nature. In fact, they almost certainly do not exist, since there's no way to produce one. (Producing a white hole is just as impossible as destroying a black hole, since the two processes are time-reversals of each other, or so they theorize)

A white hole is now a fairly accepted theory. What happens is when a super massive black hole (around the order of 10^15 solar masses) evaporates the evaportation accelerates. This evaporation is caused by virtual particle pairs and is explained in Hawking Radiation. The accelerating evaporation causes the black hole to start emitting more and more matter. As it reaches its death throes it starts to emit huge amouts of matter. This is the white hole. The only time a white hole of any magnitude would come to be is in a marginally bounded universe. This corresponds to the q0 term of Hubble's law being between 0 and 1/2. (This is assuming a cosmological constant of 0) Then afer all the mass in a galaxy collects into a super massive black hole some 10^31 years from now it is large enough to produce a white hole upon evaporation. A black hole this large would take something like 10^100 years to evaporate. Thus white holes can, and possibly do, exist but the time scale is far beyond the lifetime of the human race.

White holes fit mathematically as being opposites of black holes. Just as black hole suck matter in, white holes spit matter out, both holes are connected by worm hole. Therefore it follows new theory suggesting big bang theory was caused by white hole. Additionally, it could help answer one of the most perplexing questions: Where did all that matter from the big bang come from? Currently, more observed evidence exists to the reality of black holes than the reality of white holes or worm holes.

Multiverse is a continuing popular debate among quantum physicists. Combined Multiverse make up the Universe. The birth of one Mutliverse through big bang (white hole) is the death of another Mutliverse by means of crunches (black holes). This model is imagined and makes sense mathematically but no concrete evidence exist to satisfy the skeptics.

Scheduled in 2008, NASA will launch LISA (Laser Interferometer Space Antenna). The primary mission of the triple satellite is to detect gravitational waves caused by black holes by means of lasers arranged as a triangle between the three satellites. In addition to its primary mission, LISA will search for gravitational waves from the early big bang. LISA uses complicated elimination techniques to filter out the Earth and Sun gravitational fields to detect gravitational waves caused by black holes swallowing massive stars and other smaller black holes.

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http://lisa.nasa.gov