Special Relativity

[Dave Bagwill]

Ok - this is pushing the 'shoot the breeze' category but I'm desperate. In a non-desperate sort of way.

Confession: I never did completely work through all the math in the Special Theory of Relativity.
Confession: I never worked through ANY of it. I'm pretty much a guy who can work out "If a train leaves Boston at 35 mph, and at the same time a train leaves French Lick, Indiana at 45 mph...etc" - you know the kind.
I have read a bit about the theories but this passage has me stumped. It's from a very fine 'hard-science' fiction novel 'Redemption Ark' by Alistair Reynolds. Good epic space opera, lots of science, good characters etc.
Here's the passage, with the stump-Dave section underlined. Can you explain it?
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"Six weeks out from Yellowstone, over thirteen hundred AU. We've been maintaining two gees for most of that time, which means that we've already reached one-quarter of light-speed. A conventional ship would be struggling to reach an eighth of the speed of light by now. But we can do better than this if we have to."

Which was true, Skade knew, but there would be little practical advantage in accelerating harder. Relativity ensured that. Arbitrarily high acceleration would compress the subjective duration of their journey to Resurgam, but it would make almost no difference to the objective time that the journey consumed. And it was that objective time which was the only relevant factor in the wider picture: it would still take the same amount of time to reach Resurgam as measured by external obervers.

[John Parchem]

It is bullshit science. If they doubled the acceleration they would reach their destination much faster. They are close to the speed of light and it is true that they could not accelerate past the speed of light but they have a ways to go. Relativity would mean that they would experience the time slower. For example if it was a 2 way trip there and back they would be younger than those left behind when they returned. The slowing down of experiencing time is measurable and is used as part of GPS calculations.

[Dave Bagwill]

I'm thinking that perhaps the author (an astrophysicist) wrote a sloppy paragraph.
Of course, if you go faster, you'll get there sooner. I think he was trying to point out that the subjective experience of the relative dilation of time does not matter to the objective observer. If that's what he meant, he did not put it well.

[Dave Bagwill]

Since I'm on a 'science' kick, here some technology news - the end of the car - coming soon?

http://www.autonews.com/apps/pbcs.dll/a ... d-bob-lutz

[John Link]

The end of the car is not coming any time soon. One of the easiest ways to say something spectacular is to make it in the future, where there are no facts to get in the way. Futuristic statements are most plausible when they predict that a major trend will continue. Even then they often don't come true. Driverless cars are not yet a reality, much less a trend of any kind. With all due respect to Google, of course.