Re: relativistic acceleration stuff

[Kevin C Houston <hous0042@maroon.tc.umn.edu>]

Steve, I was going through my old E-mail, when I re-read this one from 
you and I think I have some newer (to me anyway) thoughts on them.

On Sat, 29 Apr 1995, Steve VanDevender wrote:


> required is 3.701E16 joules; therefore you have to receive beamed
> power of 3.701E16 W in order to maintain a rate of 0.011645 kg of
> reaction mass accelerated to 0.9996 c every second.
> 
> This is complicated further by redshifting; as you reach higher
> and higher velocities the effective power from the beam
> decreases.  In order for the ship to maintain a consistent 10
> m/s^2 acceleration in its frame, the beamer has to continually
> increase its power.
> 
This can be kept to an order of two magnitude. Beamer stays constant.


> If you really could maintain 1 g acceleration in the ship frame,
> you run into an even worse problem with getting beamed power --
> during the first year of acceleration, you watch the beam
> decrease in power to effectively 0!  

But at the same (well I was gonna say time but that would lead to 
confusion) in the same way, the rate of change of everything on the ship 
decreases.  It's just like going into a kind of hibernation. Thus the 
beamer sends out an energy pulse of about 2 L.Y. long.  
The crew then use the first L.Y.'s worth of energy to approach c to four 
or five decimals.  The ship then nearly "keeps pace" with it's energy 
supply, and uses hardly any at all.  This is possible because with very 
long time parameters, very little energy is needed to effect change, so 
that the crew "feels" awake, the clocks and other (mechanical/electrical/ 
chemical/bio-chemical) systems behave normally within the frame of the 
ship itself.

                                          > If you continue the
> acceleration using stored fuel on the ship, the beamer is
> completely inaccessible to you -- your velocity approaches an
> asymptote with slope c that intersects the origin at about t = 1
> yr.  You are completely unable to receive anything from the other
> side of that asymptote, or in other words power transmitted after
> about the first year of beamer (Earth) time; it's very much like
> a black hole event horizon opens up 1 lyr behind you.  Of course,
> in reality maintaining continuous acceleration indefinitely is
> pretty much impossible, but you are going to have to expect that
> you won't get much beamed power once you get very close to c.

No, I won't get much beamed _energy_ , I'll have plenty of power tho' 
because each of my seconds becomes worth hundreds of beamer seconds.  So 
when I absorb one seconds worth of energy, it suffices me for 
nearly two minutes beamer time because my demand for energy (in any form) 
has decreased.

Kevin