I can prove that time travel is impossible.

It's pretty simple really. You don't need any Einsteinian equations or light cones to prove it. Just simple logic.

See, everything that humans invent becomes a commodity eventually. It's just a matter of how long it takes to get the cost down enough. Look at computers. Back in the seventies, computer engineers were dismissing the idea of personal computers as nonsense, yet how many families don't have one today? There are even efforts to get computers into developing countries to aid in education. “One laptop per child?” Who would have believed it even early in my lifetime?

Everything becomes a commodity eventually. There is no force on earth that can stop this.

So, if time travel is possible, once it's invented, it's only a matter of time before it is available to everyone.

Now, there are lots of stupid people in the world. Some of them have money. As a result, if time travel were invented, it would eventually be available for stupid people to do stupid things with.

So toss away your ridiculous Star Trek rules about not going back into the past because it might affect your future. Somebody is going to try it. In fact, once time travel becomes cheap and easy, lots of people are going to go back in time. Someone will want to prevent the Kennedy assassination. Someone will think they can prevent Hitler from being elected. Someone will go back to September 10, 2001 and invest a bunch of money in cell phone companies.

In other words, if time travel were to be possible, we would have met time travelers by now. Period. We're talking about the future here. There are an unlimited number of years ahead of us, and if time travel ever became possible, someone would have dropped in by now.

Period.

In bringing up this point, I've had several arguments come to light, and I will quickly dismiss the most common:

• The government will regulate it: Right, like they regulate illicit drugs? Perhaps with the same efficiency that they protect music from being pirated on the Internet? The average government is completely unable to regulate anything.
• What if the power requirements are too high for the average person? Well, then wait a few years. In the 1930s, the average automobile had less then 20 horsepower. Nowadays you can't get one with less than 80, and they even get better gas mileage. Compare the cell phone battery of today to the cell phone battery of just a few years ago. Our ability to generate power just keeps getting better.
• People will be smarter in the future and won't risk problems by going back in time: That's just too laughable to respond to. Maybe the society as a whole will be smarter, but there will still be idiots around who can get their hands on the technology and use it stupidly.

So, the inescapable conclusion is that time travel is impossible. Because if it were possible, someone would invent it. And if someone invents it, it will eventually be a commodity. And since there has never been a time traveler in the history of the world, that means that nobody has even traveled back in time.

So time travel isn't possible.

Period.

But I'm still going to write a story about it.