If it were, the time that Louis Wu spent there would have seemed very short, but would have actually been years. Was this ever addressed?

2 Answers 2


Well, it really depends on how long he was there, and the exact speed of the Fleet. Time dilation increases way faster as you approach the speed of light.

Time dilation formula

Time dilation factor

At 0.9c the dilation factor is about 2.29; at 0.95c about 3.20; at 0.97c about 4.11; at 0.99c about 7.09; at 0.999c is about 22.37; and at 0.9999c it's about 70.71.

Even if the Fleet was travelling at 0.9999c, staying there for one day would only mean 70 days to the outside world, which is a difference small enough to be ignored. At slower speeds the differences get meaningless pretty fast. They just took a short walk across a few stepping discs and spent some time discussing with Chiron. I think one day is a very generous upper bound on that.

Of course, if they were going just slightly faster than that, the differences would be more much pronounceable.

  • One thing to remember about time dilation is that the acceleration slows down the closer you approximate c. It's perfectly reasonable that they might just stop accelerating after a while, it would cause more headaches and not really be speeding them up any. Apr 25, 2011 at 18:20
  • Also, see my answer (scifi.stackexchange.com/questions/3019/…) to see what the speed likely was, around 0.7-0.8c, not quite enough to have a serious affect, but close enough to say that one is approaching light speed. Apr 26, 2011 at 2:14

Remember, from the Fleet's point of view, the rest of the galaxy is what's moving and experiencing time dilation. The impossibility of reconciling these two points of view when someone visits the Fleet in a hyperdrive ship is basically the reason why ftl travel isn't actually possible. So if you're on Earth, the puppeteers appear to experience about 0.6 days for every day that you experience (the Fleet is travelling at 0.8c), but if you're with the Fleet, then Earth experiences 0.6 days for every day that you experience.

  • 3
    No, that is not how time dilation works. Time dilation is very real, hyperphysics.phy-astr.gsu.edu/hbase/relativ/airtim.html Apr 25, 2011 at 20:55
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    Yes, time dilation is absolutely real. But it depends on your inertial frame of reference -- there's a reason why relativity is called relativity. It really is true that the answer to "What's the difference in time dilation between the Earth and the Fleet of Worlds" depends on whether you're currently on the Earth or on the Fleet of Worlds.
    – Mike Scott
    Apr 26, 2011 at 6:32
  • the thing is, if the fleet has been accelerated with respect to earth, that is discernible from the case of the earth being accelerated with respect to the fleet; it was the fleet that was accelerated, so it is on the fleet worlds where time would dilate, and not vice versa.
    – JustJeff
    Apr 26, 2011 at 20:52
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    No, it doesn't work that way either. The answer really does depend on your inertial frame.
    – Mike Scott
    Apr 27, 2011 at 6:18
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    The viewpoints would get reconciled if you travelled from the Fleet of Worlds to Earth in normal space, but if you use hyperdrive then all bets are off, you can't say what will happen (unless you're the author).
    – Mike Scott
    Jul 31, 2011 at 6:29

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