Science fiction belongs to a genre of writing called speculative fiction, which also includes fantasy. Perhaps the easiest way to define Speculative Fiction is all stories that take place in a setting contrary to known reality (Card 17). Which include:

1. Any story set in the future, beings future technologies cannot be known.

2. Alternate world stories, or stories set in a past that contradicts historical fact.

4. Stories set on earth before recorded history.

5. Stories that contradict a known or supposed law of nature.

Stories set in worlds that follow our rules are Sci-fi. If it is set in an universe that doesn't follow our rules it's fantasy.

Many sci-fi stories fall into several of the above categories. Star Wars for example takes place in an alternate world. It also has elements that contradict laws of nature, such

Time Travel is another common theme that has been with Science Fiction throughout it's evolution. Beings known scientific laws make time travel virtually impossible it falls into fifth category mentioned above. Depending on were the author takes the story it could also fall into the first, second or forth category as well. H.G. Wells 1895 novel The Time Machine was among the first works to highlight this aspect of sf. Since then thousands of novels, novellas and short stories have been published that are based on the principles of Time Travel. The technological thriller Terminator, in which a robot is sent to the past to change the future, is an example of time travel in modern movies. Which brings us to another common theme in science fiction, artificial intelligence.

2. A robot must obey all orders given to it by human beings except where such orders would conflict with the First Law.

With the every growing technology of the 21st century who knows what doors will be open for science fiction? What new speculations will writers have for the decades to come?

The most common and generally accepted form of sf is those set in the future or that speculate future technologies. Visions of future in these stories do not have to be correct and often times are not. Take Orson Wells novel 1984, its grim vison of the eighties was far from the truth. This does not make his novel wrong, because most authors don't pretend that what they are writing will ha

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