I think his point is that this is like having a debate about how hyperspace works in Star Wars, or how phasers work in Star Trek. The tech is a plot device best assumed to be far outside the reach of today's science.

Part of that assumption is that the current version of physics we understand is incomplete and at worst wrong. There is little use quoting a source proven wrong within the world of the story.

Besides, I came from the future to write this comment, so the article is prima facie wrong.

There is a class of things it's possible to be very sure of.

For example, I feel very sure there's no such thing as blue weight. The expression "blue weight" is syntactically legal, but that doesn't mean it refers to anything. "Time travel" appears to be in the same category. Syntactically legal, but you find that if you try to express precisely what you mean by it, you can't. It's effectively a type error, like asking for the square root of a stream.

Incoherence as a concept is a different sort of impossible from mere technological "impossibility," like e.g. a pill you could take that would let you survive in outer space without a suit. You can say what that means, even if you can't do it. I have never heard a coherent explanation of what "time travel" could even refer to.

We're travelling through time right now, and not even at a fixed velocity given relativity. That makes the question whether you can control your velocity, not whether you can travel.

So we can change the velocity at which we travel through time? To what, 2 seconds per second?

Yes, you can travel two seconds forward in time for what appears to be one second to you. It depends on reference frames and velocities.

If you could travel back in time (not saying anything about forward), would we not have seen evidence of it by now? If you can travel back to a different "time stream" of sorts, then I'd argue its not really the same "time", but rather another one that happens to mirror the one you intended to travel back to (except that you're there when you shouldn't be and any changes you make).

RTFA

> 2) You can't visit any time before your time machine was built.

I think this is a very strange assertion to make. I find it more likely that one of the following is true:

1) Time travel is not possible

2) We'll wipe ourselves our before we discover it

No, the article is retarded. It compares fiction with fact and then goes on about why the fiction is wrong - its fiction! Its not meant to be right. Also, we don't KNOW that what he said is actually how time travel would work, were it possible. So its stupid.