We're making something that's called a thermopoltaic device.
It's an alternative way to make power that doesn't use steam or turbines.
It uses the fact that you can shape and scale the amount of energy that comes
out of a flame uh as light and tune the PV cells that can absorb that
light uh and turn it into electricity. And so people always ask, you know, how does
this scale? you know, does it work well when it is really small?
Does it work well when it's really big? And the crazy thing about it is it
seems that the the physics does scale across like all the way down from a single
sodium atom to uh imaginable Dyson sphere around Sagittarius uh a the super massive
black hole in the center of our galaxy. So how does this work?
Um so basically uh I I say that uh you can define a Dyson sphere as
like you have a luminous object that has energy that is that is surrounded by
hopefully an insulated set of solar cells or or a PV cells that photovoltaic cells
rather that convert that light energy into useful electricity so you can do work
and you start with the atom. So, this is actually a uh real time Schrodinger
evolved. Let me see if I where's my where's my cursor?
There it is. All right. This is actually a real time uh Schroinger equation for the
sodium atom. And it's basically I had never seen this.
This was not this was not available when I was a physicist physics student.
Um but uh it's running in the browser. It can work in your phone.
Uh all this stuff is going to be up on Dyson Sphere.
FYI fyi. Um and uh basically sodium and all the alkali atoms are special because
they have essentially they've got a full shell uh and the nucleus and that's all
tight together and doesn't interact much you know full molecule and then on the
outside you have an easily excited I like to call it an incel electron which can
easily be knocked around and it turns out they're rather single-minded so they can
very rapidly um they basically work as a dipole.
The electron moves back and forth and then u and then the much heavier nucleus with
all the cells has an opposite charge and so it moves back and forth and not
only is it an extremely strong and so it emits this incredibly bright yellow light
yellow jacket yellow light. This is this yellow uh sodium discharge.
Uh it also they they work together. So we think that this is actually pushing into
what's extremely interesting for me. Um you know people are like oh a lot of
quantum things require low temperature. Uh so some of the there were a bunch of
Nobel prizes won for Bose Einstein con condensates is extremely low temperature um
which used this kind of atom an alkali atom and particularly sodium uh in order to
show that there's collective effects. And this is the same as two subwoofers that
are in a in a building in phase with each other.
They couple together and they they they output more power and there's a it's not
quite lazing, but it's something called super radiance, super absorption and super
transfer that ends up dominating the radiation.
Anyway, it's getting a little complicated.
The point being, the sodium atom is incredibly bright.
If you calculate out just how much energy once you've excited it, the rate of power
that it can that it can put out, it's extreme.
Like you can end up with megawws in a liter.
And but what happens is it doesn't just go straight out.
It also absorbs. It has a high resonance.
It's like a really really really imagine the best possible acoustic resonator that
might have a Q factor of like 20. This has a Q factor of thousands and
thousands. So it it it also absorbs. So the radiation is trapped and so the
question is how does it scale? Does it scale in a way that is good?
So um starting from the sodium atom we can scale to what we've done in the
lab. So um this is a the world's highest temperature type heat exchanger.
Uh and we've developed it. It uses ceramic that is 3D printed in a kind of
a a photo resin that uh you make into this kind of compound arch shape.
It's called a triply periodic minimal surface.
And what that means is because it has all this curvature, it's able to maintain the
incredible temperature differences across um you know from from here where it's air
coming in less than 100° to over here where the exhaust is coming out where it's
it's it's nearly 1400° the boiling point of salt and salt is how we get this
the the sodium in. So it's actually in a chemical loop.
So it goes um salt first becomes mo molten and then it has a high surface
tension and it wicks around all of the surfaces including uh the tube um and
including all of the different uh surfaces inside the heat exchanger and that
allows it to be continuously refreshed and act as a resonator while not being
itself consumed. And the reason this works is because the sodium chloride has the
strongest bond. It's the strongest bond energy because the one's on the left side
of the periodic table, one's on the right side of the periodic table.
This one's an extreme in cell. This one's extremely well, the molecule needs
another member, and they connect. I They should teach chemistry this way.
Anyway, um so, uh what that allows you to do is convert almost all of the
energy into this single uh wavelength, almost this single wave.
And what you get is if you can compare it.
So this is wavelength and this is the amount of energy uh per and this is
a log chart. So almost all of the energy is showing up uh right here.
It's actually um this is actually uh measured uh from from our system.
Um and the there are two kinds of silicon cells plotted here.
This is the internal quantum efficiency of a silicon cell.
And this is internal quantum efficiency of indium gallium phosphide, which is the
the highest efficiency cell to match that yellow.
And as you can see, we're much closer. So, so the way that solar cells work
is um it's called the photoelectric effect.
Not the only thing Einstein won the Nobel Prize for, but sure.
Oh, sorry. Okay. Sure. Uh little closer.
Hopefully some of the earlier can be fixed in post.
Um so the amount of energy um that light transfers comes in discrete packets
quantum mechanics photons. Uh if you have more energy than what's called the band
gap of a PB cell that extra energy is wasted.
If you have less energy then it can't absorb it at all.
So ideally you want your PV cells to have a band gap that is like just
underneath the uh exhausted power and that's that's here.
So this is a much better light source than just a sing a sun.
So as we scale the system however we can actually change it.
It's a little fiddly here. We can actually change it and as uh hopefully this
works. Uh so is it changing? No, it's not.
All right. Unfortunately, uh my claude must have busted this.
Uh immediately before, uh the fable was so great.
Anyway, uh so all right. So, so what is yeah set back we have setback science
by one week. Uh so um what happens when you have an increasing amount of power
is because of this trapping you get an increased amount of energy in the excited
states. And those excited states uh can still leak out energy in different ways to
other uh luminous uh lines. And one in particular when you have two excited states
and they collide they can do what's called a pooling reaction.
get one of them up to an even higher state and then when that jumps down
that's a near infrared which is right here.
So what should it be happening when I'm scaling this uh is it will go up
yeah go up a lot. So um and it actually the first thing that happens there
is um yeah first thing that I don't know why it's fiddly uh but um actually
it it it again this is logarithmic so there's quite a lot here but then this
a secondary can be added in which you can convert um that excitation into uh even
more infrared and even better match for silicon.
Why is this relevant? Silicon is like by far the cheapest source of energy in the
world. It's just only available when the sun is around.
So if you can tap into this with this light source, you can produce power
continuously. Um so what are the kind of scales that we're talking about?
Well, we can first start talking about like the first thing that we kind of want
to make is something that can power a Starlink Mini and your Mac Mini and so
on. But um as a uh as you get larger and larger uh it starts to
get more more and more interesting. So uh friend of mine uh makes private jet says
you need about 1 megawatt to fly. Uh a lot of people are like hey Danielle
how quickly can you produce 100 megawws forgetting how much it will cost um because
we desperately need it. um can it scale to that?
And uh one thing I find I found very useful to convince Claude about this uh
because it would keep making simplifying assumptions that was less extreme.
It's like well one of the things that's the highest power that we ever run is
like a um a rocket launch. So, if you have a Starship Superheavy launch or a
static fire when it stays on on the ground, the amount of power out is 330
uh gawatt, which is an enormous amount of power.
But if you've ever I don't know if you you've ever looked next time there's a
rocket launch, notice how it's yellow when it's on the ground, when it's close to
the ground, and then it turns white. Why does it do that?
The reason is the tiny amount of trace sodium that's just from the sea salt comes
out and lights up the whole thing. You you also saw the same thing when the
Blue Origin rocket exploded. So what if you actually use this tech technique to
make a system that can actually uh produce an enormous amount of of power in a
single installation. So if you calculate it out uh the amount of total power that
you're generating from from that amount of of of fuel you know which is like
methane you know liquid natural gas and oxygen which you can just condense from the
air um that is if you converted it approximately the amount of energy about 100
amount of power about 100 gawatts of power in a single installation which is about
the amount that is added to the electrical grid in the United States in a single
So uh completely different kind of uh power plant.
So extremely interesting. So what about building a Dyson sphere at an even greater
scale? So there are kind of two branches here.
Um one thing is in a a for an earth shade.
So one thing people talk about is as you increase the amount of power that goes
to AI even if it's green it increases the amount of waste heat on earth eventually
we get cooked what do we do so uh one of the things that you can
do is you can figure out okay how much anthropogenic global warming have we already
cooked into this thing and uh let's put a Dyson swarm just you know for good
weather put it in L1 which is the Lrange point in between Earth and the sun
and it at 0.01% of a a a shade like a a planet shade that will
cancel out all the global warming. It's also 200 terowatts of incoming power and on
the on the order you know near near to 100 terowatts of power right um so
that's a very interesting thing for uh AI especially if you can start producing the
solar panels on the moon uh because the the the moon regalith itself contains
silica contains all kinds of oxides and uh so you can make solar cells it's also
dramatically easier to get something into lunar orbital velocity and once it's in
lunar orbital velocity, it can slowly maneuver to wherever it needs to be with
light um and uh electronic uh transport.
Sorry, I know I know this is a small room and it seems like microphone it
a whole lot, but it's crucial to just speak into it.
this pretty directly just so sorry I'll try to have it locked here but maybe there
should be a compressor somewhere um okay all right great um so if you have u
if you have an earth shade then basically up to the design point of it is
providing the amount of cooling that we want this is a great place to to get
energy and it could be substantially cheaper than even earthborne energy if you can
generate uh the satellites and send them and basically you can spin launch or or
rail gun launch to lunar orbital velocity and use almost no energy compared to
launching something from the earth's surface.
So I think it's good for alignment if uh AI eventually gets power off of Earth
because then we don't get cooked by the waste heat.
Um in addition to the fact you know we're currently we're burning a lot of fuel.
Um but then something it was once you get to really large scale.
So you you you you basically you have heavy industry near Mercury, you start to
disassemble it and you you you you can send stuff out, you know, into the ecliptic.
There's so much extra power uh in the sun.
You can actually change the direction that the energy is is going.
You can have um this the sun has an enormous magnetic field and it's p it's
moving through the milky way and so it's actually accreting gas and it's exhaust
and exhausting gas and and photons at the same time.
So if you change where the light is going out and you change where the exhaust
is going out and you change where stuff is coming in, this is basically a busousard
uh ramjet which is this idea where you actually make guess I see in the audience
you make a fusion reactor that absorbs the interstellar gas and and moves around.
So what can you do with this? I'm not saying it's easy thing to do but
this is how a awesome way to make a generation ship.
Over eons, the sun can scoot around throughout the Milky Way, visit other stars,
and potentially find another star that can scoot around even more.
which means that you can get to the final prize which is uh if you have
energy uh if you have at the center of the Milky Way a super massive black
hole the amount of extractable energy when you drop something into the accretion
disc it's it's about 50% of the of the rest mass energy which is enormous which
is like about 50 times the amount that you would get out if you fused everything.
Okay. Um, and the amount of power that's available if you were to do that is
of the order of 10 the 30 33 watts. Uh, which is like just so dramatically.
I had a big argument with Elazar Yudkowski last night, you know, um, much respect.
He's like, you know, they'll they can use you for energy and they can use you
for mass. And it's like, well, there's like 10 to the very large number of of
of more energy and mass out there in space.
It's a big place and we don't necessarily have to set things up for resource
conflict. We can use ideas to to get out of it.
Um, so let me see if I can show a few other things that didn't quite
make it into this this flow. Just one second.
Uh and then we can probably discuss um well yeah sure sorry oh uh Dyson sphere.fyi
which I I I hope is is up right now. Let's see if Claude managed it.
Yeah. Unfortunately uh this part isn't working.
So I have to fix that from my Cloudflare settings.
But um yes uh it will it will be up and the intent is so I
I I discovered um one of the things that people always ask is you know why
didn't anybody ever oh why didn't anybody think of this before and there's usually
a lot of reasons. I mean this is pretty esoteric.
You need to know at least a few things sort of you know how sodium lights
work or fireworks work, how PV cells work and and and light divides into different
wavelengths. Um and you need to decide to build it which involves high temperature
flames and designing that's all right. Um and uh you you need you need to do
all these different things. But um I was like why why isn't there any study of
this? Like there there were 20 different ways to do thermop photovoltaics and
nobody decided to try uh adding sodium when this is known like this is demonstrated
in high school physics class you know just just flame tests um and and and these
are the most efficient lights in the world.
These highress sodium lights are the most efficient um lights in the world.
Uh let me just let me just move back here to where we at.
Um yeah. So so this is a a one-dimensional uh simulation uh of how much uh
energy gets out into each wavelength. So as you in you see it as you increase
the amount of um this is in WM. If if you tell your AI to use
WM everything gets incredibly fast. Uh okay.
So as you increase this you get more and more of this um self-traed line and
then you get uh more and more energy coming out in this um 819 this near
uh near infant. Yes. Sorry. Sorry. All right.
So this is this is the amount of pressure of the primary sodium and you can
have a a secondary sodium that that that basically um traps it like it like an
annulus of of of additional resonant material that's just trying to trap it.
Um and uh this this will be up as well. What what I was trying to
get to is um there is a code at Lawrence Liverour that does radiative transport and
the reason you can't have it is because it's used for Hbombs, but I'm not going
to use it for that. So, I'm making my own.
Uh uh and and and it's going it's going to go up on our our website
and and and up here and it just isn't uh integrated yet.
Um so uh um another thing to say is that we there's sort of two really
important questions in terms of the actual physics of how this works.
One is is the emission actually coupled like a laser or like this so-called super
radiance. If you click it on or off it well it can change a lot but
apparently not with these these parameters.
All right. Maybe it's maybe it's off. Hold on.
No, it's not working. Okay. Formally, super radiance would make some difference,
some degradation. Additionally, um the amount of energy uh and the amount of
irreversibility that happens when you when you combust something, when you do a
chemical reaction, um as you get to higher and higher temperatures and you drive it
towards a steady state where that temperature is so high that the reaction products
uh also thermodynamically um they thermalize uh and and split apart.
And so the heat itself is keeping things apart.
When things are that hot, the amount of energy that is available um to the system
as you when you when you rack more, it doesn't create any uh entropy.
It it's it's it's reversible. And the um the available bond energy we think is
probably significantly excited beyond what would be the kinetic temperature.
So the kinetic temperature is the temperature of all of the molecules and and atoms
moving around. Um and you calculate calculate that.
But when when a reaction first occurs, the energy is an excited states on the
molecule and it can excite this uh light emission.
Um, and we think that because of this, we can get much much higher emission
densities than we previously had, which is exciting for the the highly tuned cells
that we have because you can match the yellow much more exactly.
And it's exciting because it means that there's more amount of energy that's in the
the yellow light anyway and trapped. And that's what creates the near infrared
light that matches silicon and gallium arsenide.
Oh well. Uh yeah. So I have been kind of blowing through it.
Maybe I can uh get some questions from the audience.
Uh sure. Yes. Yeah, that's pretty much it.
Sorry. Uh yeah. Uh sorry. Uh um to understand carefully uh it is uh we use
the energy in heat to excite sodium which produces yellow light which can be
converted efficiently. So yes. So um you did a transition from uh chemical chemical
fuel systems to solo point um I wasn't clear on what was perhaps the chemical yeah
it's a good question so the traditional Dyson sphere is you surround it you
surround the sun but different suns are different colors And actually every
astrophysical or a whole pile of astrophysical objects that we know actually have a
corona that is bright in the sodium lines that is you know it's low density but
it it's bright and the temperature if you measure it is like 10 million degrees.
The sun is like this. It's not quite 10 million degrees in in the optical uh
for Earth, but it is like that. The because stars are different colors, your
optimization is going to be different for each different astrophysical option.
Um blue, red giant star, but you can convert the energy using a kind of uh
secondary. So one can imagine for the sun that you actually don't exactly know best
way to do this but get more sodium into the um layers of the sun and
it will emit uh it will emit light in that band.
But probably for for for the sun it doesn't make a huge amount of sense to
like engineer the whole thing to be emitting specifically at the extreme end when
you have a small star you can add um or or or or like the sagittarius
like if you have an accretion disc or something if you have sodium in the accretion
disc when it's a moderate temperature it will emit incredibly brightly in the
yellow um and then you can absorb Yes. Yeah.
So, could you like have two layers? One which is just a block like a ghost
block sodium that reriate or that would that be less activated?
It it could be. There's there's long been ideas of like a they call it a
mattressa Dyson sphere where you have multiple layers and the one of them radiates
out and you you cover the other. But if it depending on where you put the
atoms, you can pump more of the energy and use it and then recycle the rest.
So if you had a cavity that was like a very good mirror um and then
uh you you pick out only this uh part of the spectrum, then then that that's
a way to do what we're doing. But astrophysically it's difficult.
I mean mo most of the time when you're doing a Dyson sphere, you really are
going to want to have a a swarm. you're not going to have a complete cavity.
The energy is going to go back into the sun.
But it is, but if you have a partial cavity and you like let light out
or let exhaust products out in one direction, uh you can do all sorts of things
including like like I said, scooting around the local neighborhood.
take the first lickable right so um we're trying to make over the next couple of
years both smallcale devices that are your general purpose utility provides power
heat light water just condenses the chemically created water um at small scale and
we think that this will be you know a general purpose sidearm everyone's going to
want Um at large scale there's a huge demand for data center power and so we
are trying to find hundreds of megawws or gigawatts of basically natural gas um and
also at a place where you can generate a lot of hydrogen from excess solar and
so you can you can switch between natural gas and hydrogen and hopefully mostly
hydrogen um at at that much larger scale as we increase the amount of empirical
data behind if you scale this can you get higher and higher efficiencies out with
uh silicon cells with silicon cells and uh that could happen pretty fast but you
know maybe two years from go when there's a whole pile of money um and then
I think and people kept asking me hey Danielle why is Elon talking about a mass
driver on the moon this is why I don't know when He's intending to do that,
but it could happen quite quickly. Uh, Blue Origin has actually made solar cells
from lunar regalith, and you know, you don't even need to throw it very fast to
get into lunar orbit, although you need to do a little correction.
Uh, Matt, so power generation generate way over 50.
How does how does this stack up against the boats at its circuit recover?
Yeah. So, we think that we can fairly beat what's called a simple cycle gas
turbine, which is sort of 30% efficiency.
So we think 30% plus, but we think that if you if you optimize everything, you
can probably get to 60% or so what when everything is working in your favor.
And you can also do what's called a combined cycle plant, which combines it with
spinning things and boiling water. You know, maybe boiling boiling alcohol off of
the back of the solar cells will will generate power.
And uh you need you need a certain amount of air flowing through.
So you can imagine a having a turbine on the on the back end.
And so this is how the highest efficiency fuel um systems h uh have achieved uh
a combined cycle and a steam plant over 60% efficiency.
We think we can get over 70%. long term.
Uh, good question. So, uh, well, um, at least ours.
Um, so, so it's a very good this is one of the most costic environments imaginable,
right? You have sodium chloride, which is also and extremely high temperatures.
How are we hundreds of temperatures higher than you know MIT National Labs all
that? The main thing is we're using ceramic.
So um chemically aluminina uh aluminum aluminum 2 oxygen 3 is really difficult to
react to anything else. It's such in such a a ground state basically.
Um so it it it tolerates the salt and in fact the salt makes it stronger.
it fills in all the pores and it distributes strain.
Um the second thing is we have to use these.
Um let me show you. Uh so not this. Okay.
So sorry. Um so this shape um these kind of corugations solves the critical
structural problem. So uh even though the thermal expansion coefficient of the
ceramic isn't very high compared with steel, it's maybe one/ird, it's much much
harder. It's actually like nine on the MO scale.
It's like within a factor of four of diamond.
So on one hand, the thermal stresses will become really great if everything holds
together. But on the other hand, if you have a just a little bit of strain
relief, then you can dissipate almost all that stress.
So it's like the inverse of the problem.
So the key is you have to make it curved in all of the different dimensions.
And there's a mathematical shape called a triply periodic minimal surface.
This one here is called a Schwarz diamond that divides the space into two different
volumes. And so that's the perfect sort of building block for a heat exchanger, but
also for all of the structure. So that's what we do.
And it's similar to how, you know, how does a gas turbine or how does a
a rocket nozzle survive even though the gas inside is much much much hotter than um
the melting point even. Uh it it's you do regenerative cooling.
So the amount of air that's coming in equals the amount of air that's going out,
you know, plus the fuel. So it's it's cooling on the way in plus radiator.
Yes. Yes. It's both. And you need both, but you can you you there's a fair
amount of variation you can have. Yeah. Uh is there a nuclear reactor design that
sodium in this? I am I I love this question.
So many uh many nuclear reactors already use sodium as heat pipes.
Um but it's a relatively lower temperature.
It gets to vaporized um at about you know 600°.
Um but many people have asked me hey is there any way to do this with
nuclear? And there is there's a bunch of interesting ones.
Um the main thing is it because it's heat that is is being recycled uh and
it gets very bright that way then then you can use this this technique to both
spectrally shape and also make sure that everything inside a chamber is about the
same temperature. Same way that um heat pipes do except instead of heat pipes going
out to another heat engine it's light going out a window.
Now the thing is you have to redesign your nuclear reactor completely.
I mean this works nonlinearly. Many people know that as the temperature increases
the power increases as T 4th for black bodies.
Well, it's even faster here. It's even faster.
It's almost to the 10th power um at at these regimes.
So what you would need is a nuclear fuel that is a ceramic that can tolerate
the sodium, tolerate the salt uh and can tolerate the high temperature.
So there is such a thing and actually the very best uh refractory oxides in the
universe are is thorium oxide which is in addition to being a great nuclear fuel
because it is it is breathable. Uh um the the uh it it you'll burn the
the uranium in place. First it captures the neutron, becomes uranium, and then it
burns the uranium. So when both of those things happen, you can solve
proliferation. I I think although you know there's still some other edge cases like
if you're if you have a neutron fluence, you can do you can do stuff with
that. But um you can design a system that is an amplifier.
This is my favorite where you you start with a seed fusion.
The fusion doesn't generate much power uh versus how much you put out, but it does
generate neutrons. the neutrons multiply in the nuke and you get about 16 times the
energy out per fision and you get one over uh one minus k for multiplication.
So you can get like 2,000 times as much energy out uh per per fusion which
means that you can run fusion at much much lower than Q.
Uh and so you can have a tiny little thing.
You can imagine, you know, having a completely nuclearpowered propulsion system
that you never need to refuel basically.
And that's very interesting. Yeah. Um, let's say I'm a killer and I need a lot
through like what? Uh, yeah. So, um, we think that we'll be able to get in
a modular system about 10 megawatts, maybe more in a shipping container.
Uh, I we might need to be more competitive than this because boom supersonic is
saying 42 megawatts, although no one has ever demonstrated that within a factor
within an order of magnitude. we but um those could just be stacked up at the
larger scale where you're doing kind of a monolithic thing like the super heavy
going into a salt bowl surrounded by a tower of uh like an giant cathedral tower
of uh silicon cells where they're designed to handle not just one sun of intensity
but maybe up to 20 suns of intensity. Um, it's like pretty big skyscraper type
thing, but a single installation could equal the amount of electricity uh capacity
added to to the electrical grid in the United States in in one installation.
So, but it, you know, it's still a mega structure.
It's like hundreds of meters tall, like been very large and very bright.
Um, but you know, it's not like we haven't built those.
I mean, literally the Starship Super Heavy 330 gawatt of fuel rate.
And so we could probably convert, you know, a third of that up to a half
that. Well, because it's so super linear, you Yeah, I mean, you can you can you
can see it. Oh. Uh, what uh what temperature is necessary to see the night yellow
light? So you can see it if you've got salt around on just like any open
flame like natural gas flame or whatever.
You can already see it. Um I've seen but it's super linear.
It's like really really really to a high degree.
Uh and so as you increase the temperatures so so for us the design point is
you want the the flame plasma to be at least at the boiling temperature of salt
which is 1400° C. And then I ideally you actually drive it so that the the
the chemical reaction is held near 3,000° C.
Uh yeah. Um with preheated air or oxygen and fuel.
Yes. It's a good question. Um we should talk after uh there are a lot of
things that you definitely want in a nuclear reactor.
One is passive stability. So um not liquid but actually super critical.
So if you have a moderator that is dutyium oxide and sodium chloride and super
critical that works great. Uh we can talk about when you scale up uh IPS hall
it will bench all the so does much bigger column or you more and more yeah
I mean at some point it's it's the practical fabrication limit that's the that's
the limit at the time. Uh one scale I like to think about is you know
those backyard we've got I think there's a bunch of backyard heaters with a quartz
tube. Those quartz tubes are mass-produced.
They're so cheap. They're like 40 bucks.
One of those things could probably handle about 100 kilowatts.
So that is sort of the modular scale size where if you have a hundred of
those, you know, 10 x 10 in a shipping container, that's 10 megawatts and that's uh
pretty interesting. Um as you get larger and larger, you have to start doing
construction that is tile based. This is the same thing with uh fusion reactors.
See, you have to do something different.
And instead of using a glass containment, you'll actually use the air itself.
If you have um I mean you you you instead of having the wall be right
up against this extremely high temperature thing, we have like a swirling column of
air in inside the inside the tube. And that keeps it off of of the wall
because it's it's heavier because it's colder.
Um, so but you still need to get the energy out somehow.
So there's there's there's got to be um so we're probably it's probably not ideal
to do an an open system. You probably want a cavity.
And we've experimented with basically quartz, which is great, but eventually gets
corroded by the salt. Um sapphire, which is great, but but it can crack and you're
terrified about it because it can build up strength uh stress and um amorphous
aluminina which is which is pressed together in something called uh hipping uh uh
which makes all the grains stick together and it makes it translucent but we don't
use that as much for experiment because we can't see through the thing.
So but that's what everybody uses for high pressure sodium lamps which have like
75% radiative efficiency although not all of it is in light that you can see.
Oh. Uh, looks like we're we got room for one more question.
Uh, I think you you were going to ask something.
No, nobody else. All right. Yes. Haha. Uh, you need you need special juice.
Um, one thing is that we kind of call it, you know, fundraising by stunts.
You know, we do all these kind of engineering things and we whatever scientific
information we can gather, but also we try to show as many people as possible with
their own eyes. I didn't bring it this this year, but last year we had a
big uh light cell um operating in one of the gardens.
It lit up the whole thing. Um, so that's one thing.
I I had previously raised a bunch of money for my previous company, Light Sale
Energy, which was compressed air energy storage.
And so I had some reputation from that. So that made it easier.
It didn't make it easy. And uh and we're still fundraising.
So, you know, um it would probably be easier if I used all the AI stuff
that I'm doing and be like, we're we're just an AI company.
However, I insist that since it's energy to AI and this is the relevant durable
constraint and that we're using the AI to understand you how to actually enact our
our company h how how to build everything and it's a huge intuition pump for like
pushing the AI to the limits and we're sitting in San Francisco that these things
reinforce each other. Uh, and so that's how we keep raising money.