<html><head></head><body><div><span data-mailaddress="kanzure@gmail.com" data-contactname="Bryan Bishop" class="clickable"><span title="kanzure@gmail.com">Bryan Bishop</span><span class="detail"> <kanzure@gmail.com></span></span> , 26/1/2015 9:03 PM:<br><blockquote class="mori" style="margin:0 0 0 .8ex;border-left:2px blue solid;padding-left:1ex;"><div class="mcntgmail_extra"><div class="mcntgmail_quote">On Mon, Jan 26, 2015 at 1:48 PM, BillK <span><<a href="mailto:pharos@gmail.com" target="_blank" title="mailto:pharos@gmail.com" class="mailto">pharos@gmail.com</a>></span> wrote:<br><blockquote class="mcntgmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div id="mcnt:g0k" class="mcnta3s" style="overflow:hidden;">It would only take a few million years to spread Neumann probes<br>
throughout our galaxy. So advanced ET either hasn't appeared in our<br></div></blockquote></div><br>I saw math somewhere about relative speed-ups and head-starts by just having a single year of a head start, versus 10 years, and versus 100 years. So in the absence of having a working von Neumann probe, perhaps using literally anything else secures victory, especially if it will take you millions of years to make anything better. (Hopefully, kinematic self-replication will not take us more than 100 years to figure out.)<br><div></div></div></blockquote></div><div><br></div><div>Over long distances speed tends to win over start time.</div><div><br></div><div>If you start at time t, at time T you will have reached distance D=v(T-t). So dD/dv = (T-t), dD/dt = -v. D = D0 + (T-t)*dv - v*dt+.... So if the delay in making faster probes is less than (T-t)/v they are worth it. Now, if T is small you might want to rush with whatever you have. But if T is billions of years, then waiting may be rational. </div><div><br></div><div>For Stuart's and mine intergalactic spamming paper we found that million-year waits for making super ultrarelativistic probes would be worth it. </div><div><br></div><div>If you are worried about pre-emption the situation changes; it introduces a penalty term for larger t, giving some optimum time to wait and develop the tech. </div><br><br>Anders Sandberg, Future of Humanity Institute Philosophy Faculty of Oxford University</body></html>