The other day I watched a movie called A Sound Of Thunder.  It was a sci-fi movie based on Robert Heinlein's short story of the same name.  Unfortunately, there was a lot wrong with the movie that didn't need to be.

1) The special effects mostly sucked!
These were the worst special effects I've seen in a movie in a long time...  the computer graphics representing a city in 2050 were no more special than what you would expect on an expensive television advertisement.  They weren't much better than a computer game's graphics.  Pathetic.  The creature effects weren't much different, although they were marginally better than the environment graphics.

2) The machinations of time travel sucked!
There was an explanatioin that changes in the past resulted in 'ripple effects', where those changes went travelled forward in time and changed everything in the future as a result of the change that occurred in the past.  *coughbullshitcough*  These changes occurred a bit at a time, where first the weather changed, then the plant life changed, and then the animal life changed, and then the humans would change.  *coughbullshitcough*  This is one of the most ridiculous things I've ever heard. 

The original short story (frack knows why they didn't just stick to the original concept!) had the changes occur like this...  You go back in time and change something.  You return to where you came from.  You find that the world you remember is now different, because of the change you made. 

I'm sure that the reason the movie screwed this up was so that they could have Jurassic Park-like effects, with strange creatures chasing people around in the present day, without having the people change until the last moments.

3) The theory of time travel sucked!
Due to the ripple effects within the movie, they discovered that they couldn't travel back beyond the time location of the next approaching ripple.  So they instead theorised that if they travel back to hundreds of years before the change occurred, they could then 'slingshot' forward to where the change occurred.  *coughbullshitcough*  If they could travel back to hundreds of years before the change, they could frackin' travel back to where the change occurred! 

Ludicrous bullshit that made no sense, on top of bad special effects, made this movie a waste of time.  Which was a real pity, because the story and the concept were excellent. 

I'll take this opportunity to say that the theory of time travel behind this story is one that I absolutely don't believe is possible.  This theory of time travel is such that you could go back and kill your mother before you were born, therefore preventing you from going back and killing your mother before you were born....  A paradox without resolution.

The only theory that makes sense is the 'alternate reality' theory.  This is the one where if you go back in time to kill your mother before you were born, then a new reality branches off from that point which doesn't include your birth.  This reality is then that much different without you having an effect on it.  You would exist in it only as the time traveller who went back in time to prevent yourself being born.  Since you now exist in a reality where you were never born, which is different to the reality you came from, you can never return to your own reality.

Any attempt to go back in time to change the past, or even to leave behind evidence of your presence, would immediately create a new reality where such things happened.  If we, in our reality, ever find evidence of time travel to the past, then it could only mean that our reality is the result of that change.

I don't think the evidence of time travel will ever be found in our reality.  I also don't think that any time travel experiments will be successful.  I believe the only success will be when they can work out how to detect and travel to the alternate realities.  That will be the only way they can monitor the results of changes to reality, by making the change and then detecting the reality that resulted from that change, and seeing how things turned out.

I can also imagine that it would lead to exploitation.  If you have the ability to change reality and then see the results of that change in a reality that's not your own, you can experiment with anything you like.  You can create realities based entirely on your desire to see the results of chemical, biological or nuclear warfare or experimentation.  The possibilities are endless, as there is no limit to the number of realities that can exist, and the number of possibilities to explore.

Technology like this would be hundreds, if not thousands of years in the future.  It would make humanity 'gods', able to monitor a reality and manipulate events within it, with each manipulation creating new realities.

How do we know that 'God' wasn't actually a highly advanced race or being that technologically manipulated our own race, and the result is legends of God that we have today.

Anyway... A Sound of Thunder wasn't worth watching.  Don't see it, you won't miss anything.