[ExI] Reinventing SETI: Why Our Alien-Hunting Playbook Needs an Upgrade

[Keith Henson]

2000 ly in diameter, radius 1000 ly.

The nearest blinker is 511 ly.

Keith

On Mon, Sep 29, 2025 at 12:03 PM Adrian Tymes via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
>
> Wouldn't a 2,000 ly radius over 3,000 years be 2/3 c, not 1/3?
>
> On Mon, Sep 29, 2025, 2:53 PM Keith Henson via extropy-chat <extropy-chat at lists.extropy.org> wrote:
>>
>> I make the case that we have seen aliens.
>>
>> Of course, I could be wrong. I was, for a number of years, among the
>> people who thought the blinking of Tabby's star had to be natural.
>> But finding a couple of dozen blinking stars in a 2000 ly radius
>> around that star convinced me that it is not natural.  Assuming it is
>> aliens, you can conclude a few things, like FTL does not exist, or
>> they would be here.
>>
>> The AIs say they have been in space for 3000 years; if so, they have
>> spread out at around 1/3 of c.
>>
>> Independent of what we are looking at, it seems that our long-term
>> fate is to exist as uploads in data centers out in the computational
>> zone, far out from the habitable zone where the cold makes computing
>> less error-prone.
>>
>> YMMV
>> Best wishes,
>>
>> Keith
>>
>> On Mon, Sep 29, 2025 at 7:00 AM BillK via extropy-chat
>> <extropy-chat at lists.extropy.org> wrote:
>> >
>> > On Mon, 29 Sept 2025 at 12:55, spike jones via extropy-chat
>> > <extropy-chat at lists.extropy.org> wrote:
>> > >
>> > > Disagree.  Our first good strong radio signals are only about a century old.  A hundred year radius sphere is not that big, about ten thousand stars in that range, and even then, only those 50 years out (a coupla thousand) would have had time to return a possibly malignant signal.  We can’t dismiss the Dark Forest notion yet.
>> > >
>> > >  <big snip>
>> > >
>> > > spike
>> > > _______________________________________________
>> >
>> >
>> > The author mentions that the whole galaxy could already have 'watcher'
>> > robots in every system.
>> > Even at sub-light speeds, in theory, Von Neumann replicating probes
>> > could be everywhere within a few million years.
>> > The 'watching' could be for contact or destruction.
>> > Thinking on that scale however, I have to wonder about the problem of
>> > keeping the robot programming up-to-date. The originating civilization
>> > could be so far away and may no longer exist. Even if it still exists,
>> > it may have changed its mind about the Von Neumann robot objectives or
>> > technology. That is a huge problem to try to fix!
>> >
>> >
>> > BillK
>> >
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