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*To*: stevev@efn.org*Subject*: Re: (Re:)^4 starship-design: The Size of the Problem*From*: T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)*Date*: Mon, 30 Sep 1996 18:39:52 +0100

Hi Steve, A while ago (August 19th) you sent this letter to SD. >While I haven't had time to do a more complete write-up, I thought I >would also mention an interesting corollary to Rex's analysis of the >energy requirements of beaming power to accelerate a relativistic >spacecraft. Not only is a large amount of power required, but the >beaming equipment must be capable of (typically) output at a rate that >can be over two orders of magnitude larger than is needed to accelerate >the spacecraft at the start of the trip. > >I'm going to present some of the math without proof or demonstration at >this time, but I'm sure it will be interesting fodder for discussion >(either because Timothy or Rex will find any mistakes I might have made >or because it shows another facet of difficulty to the problem of >beaming power). > >I've recently been working on the physics of light signals between a >"stationary" object and an object undergoing relativistic acceleration >relative to it. Consider an object undergoing uniform accleration >relative to itself; its frame position at its proper time t1 is: > >[ t x ] = [ 1/a * sinh(a * t1) > 1/a * cosh(a * t1) ] Do you still have a copy of that letter? For some reason I only have the first part of it, the rest seems to have been deleted by unknown forces. I'd like to have a complete letter once more, if you still have it, would you be so kind to sent it to me? (Note that I did get the complete letter originally.) Timothy

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