Chaos Theory: Is 'The Butterfly Effect' metaphorical or can a butterfly in Amazon actually cause a hurricane in Texas merely by the flap of its wings?

Yes, Chaos can; that's if he really puts his mind to it. It's because Chaos like to cause mischief, read Abigail and the Time Thief by Roy L Balcombe published on Amazon Kindle.

I read this in the book: http://www.amazon.com/The-Trouble-With-Physics-Science/dp/061891868X There was this great guy: I forgot the name, so lets call him [math]x[/math]. He was a really great mathematician, and was working for some organisation. His job was to model the weather in terms of deterministic equations, and simulate it on a supercomputer. Now, back in the days when [math]x[/math] was working, the computers used to be gigantic machines, that produced unbearable heat and lots of noise. They were also, miserably slow. [math]x[/math] and his team, having made this really cool model of the weather, and having written this great program for their humungous computer, were the best at predicting weather. They could accurately predict weather a whole day in advance (imagine that! No, its not sarcasm, being able to predict weather a day in advance, accurately, is really difficult) One fine day, [math]x[/math] started the simulation, as usual and waited for the results. Now since the computer was slow, the results usually took 6 hours of computer time. After around 4 hours, [math]x[/math] had this sudden urge to go somewhere, so he stopped the simulation mid way, got the partial result on a piece of paper, and went away. He came back sometime later, fed the partial result back into the simulator, and let the simulation continue. To his utter surprise, the computer predicted that there was gonna be a storm the next day! And not just any storm, a storm which hasn't been experienced in over ten thousand years! And this was surprising, because the weather had been perfectly calm for over a month, a slight breeze or two maybe, but not anything like a storm. So, he re-ran the entire simulation again, from the beginning to end, and lo! there it was, the computer predicted calm weather! He immediately realized, that the problem would have occurred at the moment he paused the simulation, and took the partial result. So, he reran the experiment, paused it exactly where he had done the last time, took the partial result, fed it into the simulator, and resumed the simulation. HE got the same storm again. What actually happened was (as [math]x[/math] successfully figured out), the computer used an internal floating point number, which had an accuracy of 6 decimal places. However, when the computer gave an output, it had an accuracy of 4 decimal places. So, by feeding the partial results into the simulator to resume the simulation, [math]x[/math] had introduced an error of around 0.0001 units into the simulation. And 0.0001 units, when converted from the simulation units to real life units, was around the same amount of disturbance that a butterfly would make by flapping its wings! (Hence the name). So, A butterfly flapping its wings to cause a storm really did happen (in the simulation atleast) However:If you want to see this in real life, think as follows. A photon comes from somewhere, and falls onto your retina. The cells on your retina, due to some physical and chemical processes, send out an electrochemical signal through your optic nerve. The electrochemical signal, sent by one cell on your retina, gets passes through hundreds of cells, reaching you brain, where a super complex neuron, with thousands of connections, fires another electric signal, which passes across, in a totally chaotic manner, through billions of other neurons. Then somehow, via that huge chaos of random neuron firing, a nerve cell gets triggered, which immediately passes down the electrochemical signal to its adjacent cells, all the way down to your finger, and you end up pressing the "Enter" key. As soon as you press the enter key, a message gets sent across continents to your friend via an equally complicated process. That is a very good way of showing the butterfly effect, and the domino effect. Something as small as a photon could cause your huge finger (in comparison) to move. Infact, the butterfly effect is in everything that occurs around us. All you have to do, is to move from the scale of "Butterfly - Storm" to the scale of "10 cm - nanometers" PS: please ignore any errors I made.

Theoretically yes. Practically might be possible but we can never attribute to attach causality of a hurricane to a butterfly flap. Causality can attached to a measurable phenomenon which is seen have a drastic effect on the end results which we observe. In the case of a hurricane,or any chaotic system, any small perturbation can in fact bring about drastic change but the cause of it will be in system parameters like earths rotation, temperature, humidity, wind patterns etc.