From spike at rainier66.com  Wed Apr  1 01:24:21 2026
From: spike at rainier66.com (spike at rainier66.com)
Date: Tue, 31 Mar 2026 18:24:21 -0700
Subject: [ExI] Fwd: announcement for talk "Storing Sunlight in
 Waste-derived Syngas"
In-Reply-To: <CAPiwVB73crbwqj8cLuuWtTVMT2YcUcdQ8DxX+JPkjiO51ii6GA@mail.gmail.com>
References: <4CM24AAR0c-jMQ7VLLuuJy7jYl-Ic-64zr5Bf1j58y2wxv1mcq2mL7RI0nwBnpypJsgy26V2uA6CEU52OQ1Ly7gk9diAVurZyOYK40GCX0c=@proton.me>
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Message-ID: <005f01dcc176$45152e70$cf3f8b50$@rainier66.com>



-----Original Message-----
From: Keith Henson <hkeithhenson at gmail.com> 
...
>>... Consumers will not tolerate intermittence in power either.  The 1999-2001 era rolling blackouts made that very clear.  The message was sent to politicians and the power company to make sure there will be no rolling blackouts, regardless of economic impact or what endangered species must be brutally extinguished.

>...That was Enron playing games by shutting down power plants for maintenance when the power demand was highest to get a premium price for power...

Well it worked.  We have been paying premium prices for power ever since.

>>... The power must keep coming.  Result: the local peaker plant, which 
> turned out to be unnecessary and is now being prepared to run a data center.

>...That's interesting.  That's the Metcalf 605 MW plant.  

I heard it was called the Los Esteros Energy Center, a 300 MW facility, so we might be talking about two different plants.

>...I remember when it was built.  It is a seriously large combined cycle plant with (I
think) two gas turbines... Keith

It is exciting to see the data center go in.  It is yuuuuuge.  There was a big homeless community out there a year ago.  They exported them to South San Jose; now the new data center takes up most of what used to be McCarthy Ranch.  Fun aside: you may recall Alviso used to be the wrong side of the tracks.  Well, it isn't that way now.  A prole can go walking down there and no need to worry.

Now with that big data center there, Alviso will likely be the happening place to live.

spike




From hkeithhenson at gmail.com  Wed Apr  1 02:51:13 2026
From: hkeithhenson at gmail.com (Keith Henson)
Date: Tue, 31 Mar 2026 19:51:13 -0700
Subject: [ExI] Fwd: announcement for talk "Storing Sunlight in
 Waste-derived Syngas"
In-Reply-To: <005f01dcc176$45152e70$cf3f8b50$@rainier66.com>
References: <4CM24AAR0c-jMQ7VLLuuJy7jYl-Ic-64zr5Bf1j58y2wxv1mcq2mL7RI0nwBnpypJsgy26V2uA6CEU52OQ1Ly7gk9diAVurZyOYK40GCX0c=@proton.me>
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Message-ID: <CAPiwVB4w92LxK0VJT_Jx5P7yR_rc-6frTLR2MJTayckcLEY0PQ@mail.gmail.com>

On Tue, Mar 31, 2026 at 6:24?PM <spike at rainier66.com> wrote:

snip
>
> Now with that big data center there, Alviso will likely be the happening place to live.

Perhaps, but I really doubt it.  Data centers occupy a chunk of land,
draw a lot of power, and evaporate a lot of water for cooling, but
they employ very few people once they are up and running.

Keith

> spike
>
>


From avant at sollegro.com  Wed Apr  1 06:18:30 2026
From: avant at sollegro.com (Stuart LaForge)
Date: Tue, 31 Mar 2026 23:18:30 -0700
Subject: [ExI] Monkeys in Space
In-Reply-To: <R6F1VKETcDFUYhS61ygjpohpksaI4kBXKWeHd4AOabdfZz2X0aTFl9hg0LhoMs95YogByy_NPNL1Eu5OR7EXPFOJuZRPQw-Yq6Y2nrwnSyc=@proton.me>
References: <R6F1VKETcDFUYhS61ygjpohpksaI4kBXKWeHd4AOabdfZz2X0aTFl9hg0LhoMs95YogByy_NPNL1Eu5OR7EXPFOJuZRPQw-Yq6Y2nrwnSyc=@proton.me>
Message-ID: <9b74d20ac0292ed5fba3eb15d2f8cd94@sollegro.com>

On 2026-03-30 02:33, Ben Zaiboc via extropy-chat wrote:

> Yes, I think that habitats in orbit make more sense than colonies on 
> planets. That would certainly solve the gravity problem, but it still 
> leaves radiation shielding (there are ways to generate artificial 
> magnetospheres, but you still need to replicate the effect of a couple 
> of hundred miles of atmosphere, for shielding against high-energy 
> neutral particles), which means a lot of extra mass, and the simple 
> fact that we need a hell of a lot of oxygen, water, and food, as well 
> as all the myriad other requirements of biological organisms, which 
> contrasts very starkly with the probable requirements of uploads.
--------

NASA is already working on that. They have tested radiotrophic fungi 
aboard the ISS and got good results. You could use the space between 
inner and outer hulls and bulk heads to store water and culture 
radiotrophic fungi (c.f. Cladosporium sphaerospermum) to act as a form 
of living radiation shield, allowing it to convert ionizing radiation 
into biomass that can then be processed into food or chemical fuel for 
the people in the colony. Turning radiation from a hazard into an energy 
source. Turning obstacles into opportunities is exactly how humanity 
will colonize space.
-------
> 
> In practice, I think that if biological humans ever do live in space in 
> any numbers, it will have to be preceded by upload colonisation and the 
> creation of a lot of infrastructure, and the question remains: would it 
> be worth the bother and expense? Especially when an uploading solution 
> exists. You'd also have to haul tons and tons of fragile flesh up our 
> steep gravity well, which is very expensive no matter how it's done, 
> vs. a few watts of electricity to transmit some data. more I think 
> about it, the less I think that 'monkeys in space' is a viable 
> scenario.
------------

I think there will be be people in space before uploads become a viable 
technology. The difficulty lies in a large set engineering problems 
encompassing various disciplines. But the problems are finite and 
solvable. For example, we already roughly sketched out a viable 
Interplanetary Transport Network and these routes could be calculated 
and optimized on the fly by computers. We are close to developing fusion 
rocket engines that  use Helium-3 as fuel. Helium-3 is abundant on the 
moon and lunar helium mining could become a space-based industry.

I, for one, have high hopes humanity's future in space.

Stuart LaForge

From benzaiboc at proton.me  Wed Apr  1 08:53:05 2026
From: benzaiboc at proton.me (Ben Zaiboc)
Date: Wed, 01 Apr 2026 08:53:05 +0000
Subject: [ExI] Reversible computing (Was: Re: ET Emergence (Was Re: Uploads
 as a group of AI agents))
Message-ID: <XBy1M0fRi5NCViVNT76o1xZJNX8qGhBBqQokYV-Xxuk8C9kl40y0Ni-UrkcNGY9yGHbzS8gt3tjePsU2w2LEG2Muyzi9v9DGYg_UZMFF6Po=@proton.me>

Isn't reversible computing a bit like the Casimir Effect, a theoretical thing that /in theory/ could produce amazing benefits, but in practice, we will probably never be able to use?

Has anyone ever actually done any reversible computing? (in a practical sense, not in the 'a glass of water' sense).

What are the practical difficulties we'd have to overcome in order to do it in any kind of useful way?

-- 
Ben


From benzaiboc at proton.me  Wed Apr  1 10:48:47 2026
From: benzaiboc at proton.me (Ben Zaiboc)
Date: Wed, 01 Apr 2026 10:48:47 +0000
Subject: [ExI] Monkeys in Space
In-Reply-To: <9b74d20ac0292ed5fba3eb15d2f8cd94@sollegro.com>
References: <R6F1VKETcDFUYhS61ygjpohpksaI4kBXKWeHd4AOabdfZz2X0aTFl9hg0LhoMs95YogByy_NPNL1Eu5OR7EXPFOJuZRPQw-Yq6Y2nrwnSyc=@proton.me>
 <9b74d20ac0292ed5fba3eb15d2f8cd94@sollegro.com>
Message-ID: <770o7m0ZLQV5FT1brdo_MHElU9gz6fG7ka1UfrFDLQOyiWJ9RfFsuSqqGmnDj2DDm-rTjztDWlWJH12faMo_35Z7BnwNfCC24UN23VS-Zcw=@proton.me>

On Wednesday, 1 April 2026 at 07:18, Stuart LaForge <avant at sollegro.com> wrote:

> On 2026-03-30 02:33, Ben Zaiboc via extropy-chat wrote:
> 
> > Yes, I think that habitats in orbit make more sense than colonies on
> > planets. That would certainly solve the gravity problem, but it still
> > leaves radiation shielding (there are ways to generate artificial
> > magnetospheres, but you still need to replicate the effect of a couple
> > of hundred miles of atmosphere, for shielding against high-energy
> > neutral particles), which means a lot of extra mass, and the simple
> > fact that we need a hell of a lot of oxygen, water, and food, as well
> > as all the myriad other requirements of biological organisms, which
> > contrasts very starkly with the probable requirements of uploads.
> --------
> 
> NASA is already working on that. They have tested radiotrophic fungi
> aboard the ISS and got good results. You could use the space between
> inner and outer hulls and bulk heads to store water and culture
> radiotrophic fungi (c.f. Cladosporium sphaerospermum) to act as a form
> of living radiation shield, allowing it to convert ionizing radiation
> into biomass that can then be processed into food or chemical fuel for
> the people in the colony. Turning radiation from a hazard into an energy
> source. Turning obstacles into opportunities is exactly how humanity
> will colonize space.
> -------
> >
> > In practice, I think that if biological humans ever do live in space in
> > any numbers, it will have to be preceded by upload colonisation and the
> > creation of a lot of infrastructure, and the question remains: would it
> > be worth the bother and expense? Especially when an uploading solution
> > exists. You'd also have to haul tons and tons of fragile flesh up our
> > steep gravity well, which is very expensive no matter how it's done,
> > vs. a few watts of electricity to transmit some data. more I think
> > about it, the less I think that 'monkeys in space' is a viable
> > scenario.
> ------------
> 
> I think there will be be people in space before uploads become a viable
> technology. The difficulty lies in a large set engineering problems
> encompassing various disciplines. But the problems are finite and
> solvable. For example, we already roughly sketched out a viable
> Interplanetary Transport Network and these routes could be calculated
> and optimized on the fly by computers. We are close to developing fusion
> rocket engines that  use Helium-3 as fuel. Helium-3 is abundant on the
> moon and lunar helium mining could become a space-based industry.
> 
> I, for one, have high hopes humanity's future in space.



I too have (very) high hopes for humanity's future in space, I just don't think those humans will be biological, or at least not most of them.

We already have humans in space, and have had for over 50 years, but I'm not talking about a few individuals, I'm talking about a substantial population, millions of individuals at least, able to do useful things (as well as happily and comfortably (and safely!) live), all over the solar system.

Consider for example, asteroid mining. Just about all of the useful asteroids are at least twice as far from the Earth as Mars is. Biological asteroid miners would need to carry with them a huge amount of stuff, go in a large spacecraft with a rotating section producing more than 0.6g (I think it was 0.8g) for them to spend most of their time in, lots of radiation shielding, a way for them to grow and recycle food and oxygen for a long time, be restricted in its acceleration and keep them sane and functional for how long? I don't know, certainly months and maybe years. All these problems are indeed solvable in theory, but I don't know if they would be in practice, or scalable to a useful degree.

Compare this with uploaded asteroid miners.
They'd need reliable power, some radiation shielding (although probably less than biological people would need), they could reduce their clock speed during long boring voyages to make them go by quicker, take large libraries of entertainment and virtual environments with them, withstand much higher accelerations, not need to be kept at physiological temperatures, not need food or oxygen or waste recycling, and their spacecraft could be orders of magnitude smaller. Many more of them could be built and launched much more cheaply and quickly.

You could also pack many more uploads into your spacecraft. Considering the distances, and the possibility for uploads to run at many times the thinking speed of biologicals, you'd probably want a much larger collection of people in your expedition, maybe equivalent to a town or even city, and the spacecraft would be their home, as opposed to a small team of biological people on a hazardous trip millions of miles away from their home, friends and family for a limited (but long) time, in less-than-ideal conditions, both physically and psychologically.

The issue of actually mining an asteroid once you're there would probably be fairly similar in both cases, except for the need for biological humans to wear spacesuits in order to work outside (but maybe remotely-operated robots would work fine for this).

The problems of each scenario are finite and solvable, but it seems to me that solving the relatively small set of problems involved in creating human uploads is closer to becoming reality than the much larger set of problems involved in supporting biological humans indefinitely in space. Just the single constraint of needing to be in a substantial gravity field for most of the time is a huge problem. That might be solvable with drugs of some kind at some future point, but that's just speculation, we have no real idea what might be involved in avoiding this problem. For uploads, zero-gravity will be an asset, not a problem, and we already know how to build computers and transmit radio signals. We don't yet know how to build large rotating habitats and launch large numbers of biological humans safely into orbit.

Another factor is what happens when things go wrong. For biological humans, almost anything going wrong in space a couple of hundred million miles from earth would mean certain death. Permanent death,  most likely.
For uploads, if anything goes wrong (that doesn't result in the destruction of the spacecraft, at least), they could as a last resort, just shut down and wait to be rescued. It wouldn't matter how long the rescue took.
But apart from this, there would simply be much less /to/ go wrong. Depressurisation, running out of air, water or food, wouldn't be problems, medical problems wouldn't exist, physical damage would be to robotic manipulators, not flesh-and-blood limbs, etc.

About the only real problems would be physical destruction of the spacecraft and massive doses of radiation from a solar storm or something equivalent (and seeing as it would be just sensible for everyone to have their minds backed-up in robust media, or even in a remote location, even these things would be survivable).

You see what I mean when I say "the more I think about it..."?

Large-scale space colonisation is not going to happen quickly (or perhaps at all) with biological humans, but with uploads, it could happen in a much shorter time. We're probably talking about months or years vs. decades or centuries.

---
Ben


From johnkclark at gmail.com  Wed Apr  1 12:09:33 2026
From: johnkclark at gmail.com (John Clark)
Date: Wed, 1 Apr 2026 08:09:33 -0400
Subject: [ExI] Reversible computing (Was: Re: ET Emergence (Was Re:
 Uploads as a group of AI agents))
In-Reply-To: <XBy1M0fRi5NCViVNT76o1xZJNX8qGhBBqQokYV-Xxuk8C9kl40y0Ni-UrkcNGY9yGHbzS8gt3tjePsU2w2LEG2Muyzi9v9DGYg_UZMFF6Po=@proton.me>
References: <XBy1M0fRi5NCViVNT76o1xZJNX8qGhBBqQokYV-Xxuk8C9kl40y0Ni-UrkcNGY9yGHbzS8gt3tjePsU2w2LEG2Muyzi9v9DGYg_UZMFF6Po=@proton.me>
Message-ID: <CAJPayv2LmW63QTqEqdxwaYoW2yzrYTFHXS1jRt9S3ubQPbU0Qw@mail.gmail.com>

On Wed, Apr 1, 2026 at 4:54?AM Ben Zaiboc via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

*> Isn't reversible computing a bit like the Casimir Effect, a theoretical
> thing that /in theory/ could produce amazing benefits, but in practice, we
> will probably never be able to use?*
>

*Very small circuits that use logically reversible gates have been built
that operate on just a few bits of information, but it was enough to prove
that the theory is correct because they beat any irreversible computer when
it comes to energy usage because they didn't need to erase any information,
Landauer?s Limit says that the minimum amount of energy needed to erase one
bit of information is  kT ln 2. The downside of those experimental
reversible computers is that although they use less energy they also
require more complex circuitry and they are much slower than conventional
computers. *

*A perfect quantum computer would be a reversible computer but such a thing
is probably impossible, a real quantum computer would need error correction
and that is irreversible. Drexler style Nanomachines can also be reversible
but when designing them you need to take the Casimir Effect into account
because it can be a problem; the force of attraction is inversely
proportional to the distance to the fourth power so it grabs on fast as the
distance between parts shrinks. Casimir attraction can also be helpful if
you want a part in your nanomachine to have something that behaves like a
spring.  *

*With careful design the Casimir force can be shaped, for example if you
use a dielectric material instead of a conductive metal the attraction is
greatly reduced,  and if you put a fluid with carefully designed dielectric
properties between the plates you can even get a force of repulsion instead
of attraction. You could use Casimir to keep two parts in your nanomachine
precisely aligned without contact, and then you could make a no contact no
wear bearing that would operate similar to the way magnetic levitation does
but by using quantum vacuum forces instead of magnetism.*


*John K Clark*


>
>
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From atymes at gmail.com  Wed Apr  1 12:58:56 2026
From: atymes at gmail.com (Adrian Tymes)
Date: Wed, 1 Apr 2026 08:58:56 -0400
Subject: [ExI] Reversible computing (Was: Re: ET Emergence (Was Re:
 Uploads as a group of AI agents))
In-Reply-To: <CAJPayv2LmW63QTqEqdxwaYoW2yzrYTFHXS1jRt9S3ubQPbU0Qw@mail.gmail.com>
References: <XBy1M0fRi5NCViVNT76o1xZJNX8qGhBBqQokYV-Xxuk8C9kl40y0Ni-UrkcNGY9yGHbzS8gt3tjePsU2w2LEG2Muyzi9v9DGYg_UZMFF6Po=@proton.me>
 <CAJPayv2LmW63QTqEqdxwaYoW2yzrYTFHXS1jRt9S3ubQPbU0Qw@mail.gmail.com>
Message-ID: <CALAdGNSoukqh=W-n_kR0EUvA+OjmwQhpEsfgZ86aR8dz0c=wCQ@mail.gmail.com>

On Wed, Apr 1, 2026 at 8:11?AM John Clark via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
> With careful design the Casimir force can be shaped, for example if you use a dielectric material instead of a conductive metal the attraction is greatly reduced,  and if you put a fluid with carefully designed dielectric properties between the plates you can even get a force of repulsion instead of attraction. You could use Casimir to keep two parts in your nanomachine precisely aligned without contact, and then you could make a no contact no wear bearing that would operate similar to the way magnetic levitation does but by using quantum vacuum forces instead of magnetism.

How would this work?  If you just had two surfaces near each other,
they would attract.  If you had a part balanced between two others, if
it got out of alignment, it would be exponentially more attracted
toward the one it was nearer - but for alignment, wouldn't you need it
to be more attracted to the one it is further away from, so it is most
(net) attracted to the equilibrium point?


From atymes at gmail.com  Wed Apr  1 13:03:30 2026
From: atymes at gmail.com (Adrian Tymes)
Date: Wed, 1 Apr 2026 09:03:30 -0400
Subject: [ExI] Monkeys in Space
In-Reply-To: <770o7m0ZLQV5FT1brdo_MHElU9gz6fG7ka1UfrFDLQOyiWJ9RfFsuSqqGmnDj2DDm-rTjztDWlWJH12faMo_35Z7BnwNfCC24UN23VS-Zcw=@proton.me>
References: <R6F1VKETcDFUYhS61ygjpohpksaI4kBXKWeHd4AOabdfZz2X0aTFl9hg0LhoMs95YogByy_NPNL1Eu5OR7EXPFOJuZRPQw-Yq6Y2nrwnSyc=@proton.me>
 <9b74d20ac0292ed5fba3eb15d2f8cd94@sollegro.com>
 <770o7m0ZLQV5FT1brdo_MHElU9gz6fG7ka1UfrFDLQOyiWJ9RfFsuSqqGmnDj2DDm-rTjztDWlWJH12faMo_35Z7BnwNfCC24UN23VS-Zcw=@proton.me>
Message-ID: <CALAdGNQ3YrV7DK3WcNy-D4-zpBdxzoJOTfOrtcRzgdCtdMP2Bw@mail.gmail.com>

On Wed, Apr 1, 2026 at 6:49?AM Ben Zaiboc via extropy-chat
<extropy-chat at lists.extropy.org> wrote:
> Large-scale space colonisation is not going to happen quickly (or perhaps at all) with biological humans, but with uploads, it could happen in a much shorter time. We're probably talking about months or years vs. decades or centuries.

Even uploads have to wait for the hardware to travel, and even uploads
would have multiple stages of "scout hardware arrives first, surveys,
transmits results back, if they're good then first colonization
hardware is launched, eventually upgrade hardware is launched".  Being
non-biological might reduce the amount at later stages, but not the
need for multiple waves - and low-thrust travel will always be more
efficient, so the fact that uploads can tolerate higher Gs won't
eliminate low-thrust trips.  It'll be decades or centuries still, even
if perfect mind uploading was invented tomorrow.


From johnkclark at gmail.com  Wed Apr  1 17:31:22 2026
From: johnkclark at gmail.com (John Clark)
Date: Wed, 1 Apr 2026 13:31:22 -0400
Subject: [ExI] =?utf-8?q?Google=E2=80=99s_New_AI_Just_Broke_My_Brain?=
Message-ID: <CAJPayv28NFKVk5bHh5RebyaMcH+9BCOQ7e_RDOTQAPthVM4GJA@mail.gmail.com>

*Google?s New AI Just Broke My Brain*
<https://www.youtube.com/watch?v=7YVrb3-ABYE&list=WL&index=1>

*John K Clark    See what's on my list at  Extropolis
<https://groups.google.com/g/extropolis>*
94e
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From johnkclark at gmail.com  Thu Apr  2 11:49:23 2026
From: johnkclark at gmail.com (John Clark)
Date: Thu, 2 Apr 2026 07:49:23 -0400
Subject: [ExI] Reversible computing (Was: Re: ET Emergence (Was Re:
 Uploads as a group of AI agents))
In-Reply-To: <CALAdGNSoukqh=W-n_kR0EUvA+OjmwQhpEsfgZ86aR8dz0c=wCQ@mail.gmail.com>
References: <XBy1M0fRi5NCViVNT76o1xZJNX8qGhBBqQokYV-Xxuk8C9kl40y0Ni-UrkcNGY9yGHbzS8gt3tjePsU2w2LEG2Muyzi9v9DGYg_UZMFF6Po=@proton.me>
 <CAJPayv2LmW63QTqEqdxwaYoW2yzrYTFHXS1jRt9S3ubQPbU0Qw@mail.gmail.com>
 <CALAdGNSoukqh=W-n_kR0EUvA+OjmwQhpEsfgZ86aR8dz0c=wCQ@mail.gmail.com>
Message-ID: <CAJPayv06K924B7=NiTZVJRJmjPss-euiR7+DDz8cw6xv1W4RQA@mail.gmail.com>

On Wed, Apr 1, 2026 at 9:00?AM Adrian Tymes via extropy-chat <
extropy-chat at lists.extropy.org> wrote:

* >> With careful design the Casimir force can be shaped, for example if
>> you use a dielectric material instead of a conductive metal the attraction
>> is greatly reduced,  and if you put a fluid with carefully designed
>> dielectric properties between the plates you can even get a force of
>> repulsion instead of attraction. You could use Casimir to keep two parts in
>> your nanomachine precisely aligned without contact, and then you could make
>> a no contact no wear bearing that would operate similar to the way magnetic
>> levitation does but by using quantum vacuum forces instead of magnetism.*
>
>
>
>
>
>
>
> * > How would this work?  If you just had two surfaces near each other,
> they would attract.  If you had a part balanced between two others, if it
> got out of alignment, it would be exponentially more attracted toward the
> one it was nearer - but for alignment, wouldn't you need it to be more
> attracted to the one it is further away from, so it is most (net) attracted
> to the equilibrium point?*


*First of all I should emphasize that a reversible perfectly frictionless
Casimir Bearing would be nice to have but would not be absolutely necessary
for Drexler style Nanotechnology, instead you could use something that
works in a way similar to the way a bacterial flagellar motor works, it
would be robust reliable and much easier to build, but it would not be as
efficient or be reversible because it would not be perfectly frictionless.
But it works well enough to do a lot of interesting things as bacteria can
attest.  *

*Purely attractive forces in 3-D will always be unstable, but if you
pattern the surface in just the right way you can cause the Casimir force
to depend on lateral alignment and even become repulsive. The pattering
creates a metamaterial that produces a periodic vacuum energy landscape
with preferred angular positions. The  teeth of a gear also produce
preferred angular positions  but metamaterials can  do it without any
physical contact, all they need is a vacuum. *

*I asked Mr.GPT to give me a design for a **Casimir Force Bearing and this
is what he came up with: *
*===*

*A **repulsive Casimir bearing is the closest thing to a true ?quantum
levitation? device at the nanoscale. I?ll give you a concrete design, then
walk through the physics and numbers so you can see how it could actually
work.*
------------------------------
Concept: a levitated cylindrical rotor

*We want to reverse the usual attractive Casimir effect so that:*

   - * The rotor is pushed away from the stator *
   - * A stable equilibrium gap forms (say ~50 nm) *
   - * The rotor ?floats? without contact *

The key trick: a three-material system

*Repulsive Casimir forces don?t normally occur in vacuum between two
solids. But they can occur if you insert a medium with the right optical
properties.*
Lifshitz condition (qualitative)

*You can get repulsion if, over relevant frequencies:*
*?1 <?medium <?2 *

*So the design is:*

   - * Rotor: high-permittivity material *
   - * Gap: carefully chosen fluid *
   - * Stator: lower-permittivity material*

A concrete design Geometry

   - * Rotor radius: R=1 ?m *
   - * Length: L=10 ?m *
   - * Target gap: d=50 nm *

------------------------------
Materials (example set)

   - * Rotor: gold (high permittivity at relevant frequencies) *
   - * Medium: bromobenzene (commonly used in experiments) *
   - * Stator: silica (SiO?) *

*This combination has actually been shown experimentally to produce
repulsive Casimir forces.*
What the force looks like

*The pressure still scales roughly like:*

*P?d41 *

*But now it?s positive (repulsive instead of attractive).*

*At ~50 nm:*

   - * Typical magnitude: on the order of 1?10 Pa *

*So very similar strength as before?but reversed.*
------------------------------
Levitation behavior

*Now the key difference:*
Inward vs outward balance

   - * If the rotor gets too close to the stator ? repulsion increases
   sharply *
   - * If it moves away ? repulsion drops rapidly *

*This creates a stable equilibrium gap*
------------------------------
Effective stiffness

*Using the same geometry as before:*

*Surface area:*

*A?6?10?11 m2 *

*Force:*

*F?(1?10)Pa?A?10?10 to 10?9 N *

*Effective spring constant:*

*k?dF?10?3 to 10?2 N/m *

*So:*

   - * Nanometer displacements ? piconewton restoring forces *
   - * Enough for stable confinement *

------------------------------
Why this is *much* better than the attractive case

*In the previous (attractive) design:*

   - * Any instability ? collapse ? sticking *

*Here:*

   - * Instability ? increased repulsion ? self-correction *

*So this behaves like:*

*A true non-contact bearing with a restoring gap*

Rotation and friction

*The rotor can spin because:*

   - * The Casimir force is mostly normal (radial) *
   - * It does not strongly oppose tangential motion *

*Remaining losses come from:*

   - * Fluid viscosity (important!) *
   - * Fluctuation-induced electromagnetic drag (tiny) *

*So the dominant dissipation is actually:*

*the fluid you needed to create repulsion*

------------------------------
The big tradeoff

*This design solves one problem but introduces another:*
Pros

   - * Stable levitation *
   - * No stiction *
   - * Passive centering *
   - * Potentially reversible (low dissipation) *

Cons

   - * Requires a liquid medium, not vacuum *
   - * Fluid introduces: *
      - * Viscous drag *
      - * Thermal noise *
      - * Possible chemical complications *

------------------------------

Where metamaterials could improve this

*Metamaterials could, in principle:*

   - * Reproduce the ?effective medium? condition without a liquid *
   - * Create: *
      - * Vacuum-compatible repulsion *
      - * Tunable equilibrium gaps *
      - * Reduced dissipation *

*That?s still mostly experimental, but it?s a major research direction.*
------------------------------
Stability check (important insight)

*This system is stable because:*

   - * The Casimir force is strongly distance-dependent *
   - * Repulsion increases faster than any destabilizing drift *

*So you get:*

*A potential well centered at a finite gap, not at contact*

*That?s exactly what you want for a bearing.*
------------------------------
Intuition

*The rotor isn?t ?floating freely? like in air.*

*It?s more like:*

*Sitting in a very steep, invisible cushion of quantum pressure that keeps
it from touching the walls.*


*How far are we?*

*We already have:*


   - * Measurements of Casimir forces in structured geometries *
   - * Demonstrations of lateral Casimir forces and torques *
   - * Early work on Casimir engineering with metamaterials *

*But we do not yet have:*


   - * A fully repulsive vacuum Casimir system *
   - * A working Casimir bearing*

------------------------------
Bottom line

*A repulsive Casimir bearing using a fluid medium:*

   - *Can genuinely levitate a nanoscale rotor *
   - * Provides passive, stable confinement *
   - * Allows low-friction rotation *

*But:*


   - * It trades vacuum operation for fluid damping *
   - * And requires very careful material selection*


*=========*
*John K Clark*
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From johnkclark at gmail.com  Thu Apr  2 13:04:41 2026
From: johnkclark at gmail.com (John Clark)
Date: Thu, 2 Apr 2026 09:04:41 -0400
Subject: [ExI] Two very recent Quantum Computing bombshells
Message-ID: <CAJPayv2ap9BywqqcfcGHJyA2sUrPfu2j4dTW4fHejVYO1NoK=g@mail.gmail.com>

*Two big developments occurred in the field of quantum computing yesterday,
and one of them may be of particular interest to members of this group
because it concerns 256 bit elliptical encryption, the sort that Bitcoin
uses. A year or even a week ago most people thought you'd need a quantum
computer with several million physical Qubits to break Bitcoin's encryption
in a reasonable length of time, but yesterday Google announced they have
found a far more efficient algorithm which if used on a quantum computer
with just 25,000 physical Qubits could break bitcoin in only 10 days.
Interestingly Google decided not to publish the algorithm, instead they
proved they have access to such an algorithm by publishing a cryptographic
zero-knowledge proof. They said they did this after consulting with the US
government. Google issue the following statement:*

*"The escalating risk that detailed cryptanalytic blueprints could be
weaponized by adversarial actors necessitates a shift in disclosure
practices. Accordingly, we believe it is now a matter of public
responsibility to share refined resource estimates while withholding the
precise mechanics of the underlying attacks. Progress in quantum computing
has reached the stage where it is prudent to stop publishing details of
improved quantum cryptanalysis to avoid misuse."*

*Quantum computing bombshells that are not April fools jokes*
<https://scottaaronson.blog/>

*John K Clark    See what's on my list at  Extropolis
<https://groups.google.com/g/extropolis>*
naf
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From atymes at gmail.com  Thu Apr  2 14:18:20 2026
From: atymes at gmail.com (Adrian Tymes)
Date: Thu, 2 Apr 2026 10:18:20 -0400
Subject: [ExI] Reversible computing (Was: Re: ET Emergence (Was Re:
 Uploads as a group of AI agents))
In-Reply-To: <CAJPayv06K924B7=NiTZVJRJmjPss-euiR7+DDz8cw6xv1W4RQA@mail.gmail.com>
References: <XBy1M0fRi5NCViVNT76o1xZJNX8qGhBBqQokYV-Xxuk8C9kl40y0Ni-UrkcNGY9yGHbzS8gt3tjePsU2w2LEG2Muyzi9v9DGYg_UZMFF6Po=@proton.me>
 <CAJPayv2LmW63QTqEqdxwaYoW2yzrYTFHXS1jRt9S3ubQPbU0Qw@mail.gmail.com>
 <CALAdGNSoukqh=W-n_kR0EUvA+OjmwQhpEsfgZ86aR8dz0c=wCQ@mail.gmail.com>
 <CAJPayv06K924B7=NiTZVJRJmjPss-euiR7+DDz8cw6xv1W4RQA@mail.gmail.com>
Message-ID: <CALAdGNS7gLy-gNRy8fmEEx66yGZAdfscMoMKouq3pN4j-VQzow@mail.gmail.com>

Ah, I missed the "liquid medium to change the refractive index" bit.  Thanks.

Though I have had trouble getting labs to make stuff with 50 nm (or
smaller) features.

On Thu, Apr 2, 2026 at 7:50?AM John Clark <johnkclark at gmail.com> wrote:
>
> On Wed, Apr 1, 2026 at 9:00?AM Adrian Tymes via extropy-chat <extropy-chat at lists.extropy.org> wrote:
>
>>> >> With careful design the Casimir force can be shaped, for example if you use a dielectric material instead of a conductive metal the attraction is greatly reduced,  and if you put a fluid with carefully designed dielectric properties between the plates you can even get a force of repulsion instead of attraction. You could use Casimir to keep two parts in your nanomachine precisely aligned without contact, and then you could make a no contact no wear bearing that would operate similar to the way magnetic levitation does but by using quantum vacuum forces instead of magnetism.
>>
>>
>> > How would this work?  If you just had two surfaces near each other,
>> they would attract.  If you had a part balanced between two others, if
>> it got out of alignment, it would be exponentially more attracted
>> toward the one it was nearer - but for alignment, wouldn't you need it
>> to be more attracted to the one it is further away from, so it is most
>> (net) attracted to the equilibrium point?
>
>
> First of all I should emphasize that a reversible perfectly frictionless Casimir Bearing would be nice to have but would not be absolutely necessary for Drexler style Nanotechnology, instead you could use something that works in a way similar to the way a bacterial flagellar motor works, it would be robust reliable and much easier to build, but it would not be as efficient or be reversible because it would not be perfectly frictionless. But it works well enough to do a lot of interesting things as bacteria can attest.
>
> Purely attractive forces in 3-D will always be unstable, but if you pattern the surface in just the right way you can cause the Casimir force to depend on lateral alignment and even become repulsive. The pattering creates a metamaterial that produces a periodic vacuum energy landscape with preferred angular positions. The  teeth of a gear also produce preferred angular positions  but metamaterials can  do it without any physical contact, all they need is a vacuum.
>
> I asked Mr.GPT to give me a design for a Casimir Force Bearing and this is what he came up with:
> ===
>
> A repulsive Casimir bearing is the closest thing to a true ?quantum levitation? device at the nanoscale. I?ll give you a concrete design, then walk through the physics and numbers so you can see how it could actually work.
>
> ________________________________
>
> Concept: a levitated cylindrical rotor
>
> We want to reverse the usual attractive Casimir effect so that:
>
> The rotor is pushed away from the stator
> A stable equilibrium gap forms (say ~50 nm)
> The rotor ?floats? without contact
>
> The key trick: a three-material system
>
> Repulsive Casimir forces don?t normally occur in vacuum between two solids. But they can occur if you insert a medium with the right optical properties.
>
> Lifshitz condition (qualitative)
>
> You can get repulsion if, over relevant frequencies:
>
> ?1 <?medium <?2
>
> So the design is:
>
> Rotor: high-permittivity material
> Gap: carefully chosen fluid
> Stator: lower-permittivity material
>
> A concrete design
>
> Geometry
>
> Rotor radius: R=1 ?m
> Length: L=10 ?m
> Target gap: d=50 nm
>
> ________________________________
>
> Materials (example set)
>
> Rotor: gold (high permittivity at relevant frequencies)
> Medium: bromobenzene (commonly used in experiments)
> Stator: silica (SiO?)
>
> This combination has actually been shown experimentally to produce repulsive Casimir forces.
>
> What the force looks like
>
> The pressure still scales roughly like:
>
> P?d41
>
> But now it?s positive (repulsive instead of attractive).
>
> At ~50 nm:
>
> Typical magnitude: on the order of 1?10 Pa
>
> So very similar strength as before?but reversed.
>
> ________________________________
>
> Levitation behavior
>
> Now the key difference:
>
> Inward vs outward balance
>
> If the rotor gets too close to the stator ? repulsion increases sharply
> If it moves away ? repulsion drops rapidly
>
> This creates a stable equilibrium gap
>
> ________________________________
>
> Effective stiffness
>
> Using the same geometry as before:
>
> Surface area:
>
> A?6?10?11 m2
>
> Force:
>
> F?(1?10)Pa?A?10?10 to 10?9 N
>
> Effective spring constant:
>
> k?dF?10?3 to 10?2 N/m
>
> So:
>
> Nanometer displacements ? piconewton restoring forces
> Enough for stable confinement
>
> ________________________________
>
> Why this is much better than the attractive case
>
> In the previous (attractive) design:
>
> Any instability ? collapse ? sticking
>
> Here:
>
> Instability ? increased repulsion ? self-correction
>
> So this behaves like:
>
> A true non-contact bearing with a restoring gap
>
> Rotation and friction
>
> The rotor can spin because:
>
> The Casimir force is mostly normal (radial)
> It does not strongly oppose tangential motion
>
> Remaining losses come from:
>
> Fluid viscosity (important!)
> Fluctuation-induced electromagnetic drag (tiny)
>
> So the dominant dissipation is actually:
>
> the fluid you needed to create repulsion
>
> ________________________________
>
> The big tradeoff
>
> This design solves one problem but introduces another:
>
> Pros
>
> Stable levitation
> No stiction
> Passive centering
> Potentially reversible (low dissipation)
>
> Cons
>
> Requires a liquid medium, not vacuum
> Fluid introduces:
>
> Viscous drag
> Thermal noise
> Possible chemical complications
>
> ________________________________
>
> Where metamaterials could improve this
>
> Metamaterials could, in principle:
>
> Reproduce the ?effective medium? condition without a liquid
> Create:
>
> Vacuum-compatible repulsion
> Tunable equilibrium gaps
> Reduced dissipation
>
> That?s still mostly experimental, but it?s a major research direction.
>
> ________________________________
>
> Stability check (important insight)
>
> This system is stable because:
>
> The Casimir force is strongly distance-dependent
> Repulsion increases faster than any destabilizing drift
>
> So you get:
>
> A potential well centered at a finite gap, not at contact
>
> That?s exactly what you want for a bearing.
>
> ________________________________
>
> Intuition
>
> The rotor isn?t ?floating freely? like in air.
>
> It?s more like:
>
> Sitting in a very steep, invisible cushion of quantum pressure that keeps it from touching the walls.
>
> How far are we?
>
> We already have:
>
> Measurements of Casimir forces in structured geometries
> Demonstrations of lateral Casimir forces and torques
> Early work on Casimir engineering with metamaterials
>
> But we do not yet have:
>
> A fully repulsive vacuum Casimir system
> A working Casimir bearing
>
> ________________________________
>
> Bottom line
>
> A repulsive Casimir bearing using a fluid medium:
>
> Can genuinely levitate a nanoscale rotor
> Provides passive, stable confinement
> Allows low-friction rotation
>
> But:
>
> It trades vacuum operation for fluid damping
> And requires very careful material selection
>
>
> =========
> John K Clark
>


From spike at rainier66.com  Thu Apr  2 17:43:47 2026
From: spike at rainier66.com (spike at rainier66.com)
Date: Thu, 2 Apr 2026 10:43:47 -0700
Subject: [ExI] epic april fools joke
Message-ID: <00e201dcc2c8$42716e10$c7544a30$@rainier66.com>

 

 

NASA Plays Incredible April Fools' Joke Of Once Again Pretending To Go To
The Moon | Babylon Bee
<https://babylonbee.com/news/nasa-plays-incredible-april-fools-joke-of-once-
again-pretending-to-go-to-the-moon> 

 

 

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