Black holes white holes and other things
December 1st 2007 08:32
The supernova remnant RCW 86 Photo: Max-Planck-Institut für extraterrestrische Physik
There are many popular misconceptions concerning black holes, many of them orchestrated by Hollywood. Television, movies have portrayed them as time-traveling tunnels to another dimension, cosmic vacuum cleaners devouring everything in sight. It can be said that black holes are really just the evolutionary life cycle of massive stars that have used up all their fuel.
What constitutes a black hole?
Essentially a black hole is the remnant of a dead star with a mass of at least 10 to 15 times the size of our Sun. If a star that massive or larger undergoes a supernova explosion, it may leave behind a fairly massive burned out stellar shroud. With no outward forces to oppose gravitational forces, the remnant will collapse in on itself thus becoming a very powerful entity with enormous gravitational forces.
the same supernova remnant RCW 86 deep field view taken by the Chandra space telescope
The influence of a black hole can be seen on other stars being obscured by nature of a black hole not letting light behind it to pass through.
When a star’s reaches the end of its life cycle it does not mean that it will explode and become a black hole. When our Sun runs out of fuel it may continue as a dwarf star having been compressed to a mass a few hundred kilometers in diameter.
In 1987 we were treated to a comic event when a star suddenly exploded and created a bright light that was seen here on Earth the light emitted outshine the planet Venus. The even t may have occurred perhaps tens of thousands of years ago.
The characteristics of an exploding star are it suddenly brightens for a few weeks and then dims to a point that it cannot be seen without a telescope. Star explosion (nove` ) have been well documented over centuries. The supernova remnant RCW 86 most likely comes from the explosion of a star observed by Chinese astronomers in AD 185. Known previously, this event is the first Galactic supernova taken from ancient written records.
Watch an animation of a black hole.
What about white holes?
White holes are highly hypothetical. According to the laws of astrophysics, a white hole is the time reversal of a black hole. While a black hole acts as an absorber for any matter that crosses the event horizon, a White Hole acts as a source that spews matter from its event horizon. The sign of the acceleration is invariant under time reversal, so both black and white holes attract matter. The only potential difference between them is in the behavior at the event horizon.
Hawking argued that white holes are the same as black holes, once quantum mechanics is taken into account.
What about wormholes?
Unfortunately, worm holes are more to do with science fiction than they are science fact. A wormhole is a theoretical opening in space-time that one could use to travel to far away galaxies very quickly. The wormhole itself consists of two copies of the black hole geometry connected by a tunnel the tunnel, or passageway, is referred to as an Einstein-Rosen bridge. It has never been proved that worm holes exist and there is no experimental evidence for them, but it is interesting to think about the possibilities their existence might create.
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Comment by Damo
For the Sake of Argument
My Apologetics
I read em but rarley comment.
I guess I am a bit slack.
I remember reading in one book about the sizes of the magic circle that black whole would make from someting the size of the Earth. The author used the full stop at the end of the sentence. Science makes science fiction look conservative and dull.
Comment by CarlCan
Astroearth
Your comments are always welcome. I wouldn't say your are slack. I think comments are valid if one needs to put accross different points of view or share an opinion and not make comments for the sake of making a comment.
Science fiction has a place in the real science if it makes a challenge or inspires some one to make a real scientific discovery by using science fiction as a catalyist in forming new ideas.
I thank you for yours at least I know someone is reading my "ramblings" :0)