Hello? Hello? Hello? It's not working. Hello? Test, test. Now it's working. Thank you. Thank you very much. So this is my last lecture already. Time goes fast. So what I want to do today is to discuss gauge supergravities and the black holes that arise. Of course, this is a whole topic by itself. And so I want to maybe be a little bit sketchy, but sketchy. I was also a little bit sketchy perhaps yesterday. And the whole point also of these lectures is to prepare for future lectures in particular Alberto and Samir, perhaps also Joao. And so I'm not going to give like a full analysis of gauge supergravities, but I want to discuss a little bit what are the main ingredients of such a theory. How does it look like?  So the whole, let's set the stage a little bit. So we're interested in black hole solutions that are not living in asymptotically flat space decided yesterday. But I'm interested, we're interested in solutions, black hole solutions that are asymptotically living in ADS. We have seen in ADS4, we have seen that if you just do the simplest version of supergravity in ADS, that was just with no matter couplings, then it's essentially the original nurse term living in ADS4. That could not be made super symmetric without having negative singularities. And so we need to do something. In fact, the analysis was also done, I think in 1999, James Liu, where you see, I think a famous paper by Duffer and you, where one studies n equals eight gauge super gravities. And so if you focus there also on electric electrically charged black holes, that doesn't do the job either in the sense that these solutions become naked singularities. But that paper will still be relevant also for a later discussion because there's a lot of embedding of four dimensional supergravity into M theory. And then eventually you want to make connections with ABGM theory and explain the entropy of black holes microscopically using field theory techniques. But that's not the purpose of my lectures. So what is gauge supergravities? So well yesterday I brought you to the point where I discussed matter couplings to n equals two supergravity. And so I'm going to leave out the hyper multiplets for the moment and just discuss vector multiplets. And if we do all the gauge fixing for the present purposes, the off-shell version is not very relevant for us. I'm interested in constructing black hole solutions, just equation of motion, no fluctuations or localization around it. So I'm just interested in constructing solutions. So that is just an on-shell procedure is good enough for that. And after you do all the conformal calculus, you end up with supergravity theories for vector multiplets, which are of the following type. So there's the Einstein-Hilbert term and then we had vector multiplets. And in each vector multiplets, there is a complex scalar. And then there is, I didn't write that down yesterday, but today I will write down the kinetic energy or the kinetic terms for the gauge fields. Let me first write it down and then say a few words about it. In fact, I wrote down one particular model yesterday explicitly on the blackboard where I had one complex scalar and I had two vectors. So i runs over the number of vector multiplets and this index lambda, which I called i yesterday, capital I, now I call lambda, lambda sigma. So i runs from 1 to nv and lambda runs from 1 to nv plus 1. The reason why there's an additional vector is because there is the gravity photon. The gravity photon is part of the Poincare multiplet together with the metric. And of course there's also fermionic terms that I'm not writing down. And so here we see the kinetic energy for the scalar fields in the vector multiplets. There is a metric on that space. It's called special scalar metric. And I gave an explicit example yesterday where I only had one scalar and this thing was just 1 divided by imaginary part of z squared. And here we have the kinetic terms for the gauge field. And this i is a matrix that also depends on the scalar fields. I wrote down an example yesterday. Then this was just the imaginary part of z and this was the real part of z. But in general this is now a matrix. This would be theta angle like terms. And all these quantities here have geometric interpretations in terms of special scalar geometry. But for the present purposes the only thing that we need to know is that all these three quantities here are determined by a pre-potential f of x. And these x's then can be parametrized by coordinate z. The reason is that yesterday I wrote down these kind of constraints. Let's say this is constant. So NIJ was made out of the second derivatives of f. And so this is a constraint on all the fields. So the solution of this is a hypersurface which has co-dimension 1. And coordinates on that surface are the small z's. So these z's end up being here. Another way of saying this is you do the super conformal quotient from the off-shell formulation to the on-shell formulation. And then you exchange, you change the axis for the z's. You go down in one complex dimensions. So this is just one constraint. There's also the U1 constraint that allows you to go down. I'll give explicit examples. So important examples that are relevant kind of for our discussion is this model here. Let's say you have four vector multiplets or three in the four vectors and three scalars. So this is a known example. It's the STU model essentially. Or you can also go to another example of a pre-potential that is often studied is this one here. It had to be homogeneous of second degree. Both of them are homogeneous of second degree. And in fact, for those who know this, these two pre-potentials are related by electromagnetic duality. Sometimes one makes truncations. You set certain fields equal to each other. If you're off-shell, you can easily do that. And so for the purpose of my talk here, I will look at the case where number one, two, and three are really the same. And so I'm going to study this particular model, which is x0 and x1 cubed. It's still homogeneous degree. So of course, now I have only two vectors, vector multiplets. And I can do the same thing here. You can have f equals x1 cubed over x0. So that's kind of the choice of this pre-potential basically dictates and determines this entire Lagrangian. So we have also gravitini here and the gauge genie. And so a natural question that comes to your mind is, hey, we have gauge fields, but nothing seems to be charged under the gauge fields. All the fields are neutral. The scale of fields is just a flat derivative. There's no connection here involving this. And if you write down the kinetic terms for the gravitino or the gauge, you know, they're also not charged. They're neutral. So the question then is, well, can we make some of these fields charged under the U, under the U1s that I have available here? And the answer is yes. And in essence, that is what gauge supergravity is. You're charging certain fields under vector fields, under gauge fields that are already available in the multiplets that you have. And there's different choices that you can make. You can make different fields charged under these U1s. For instance, I can make these scalar fields to be charged under the U1s. But I will do that maybe when there's time left over. But inside the fermions, there's a gravitini. I can also make the fermions charged under the U1s. And that's a different choice. And there are different types of gaugings that you can do. I didn't write down the hypermultiplot. They also have scalars. And I can gauge them. I can give them charge. And so the gauging that I will look at most of this lecture today is gauge, give or gauge the gravitini. I have two of them. Give them charge, in other words. Yeah. Now, the way you do that is just by using the ordinary procedure of gauging. You just covariantize derivatives. And you couple the fermions to the gauge field by minimal coupling. And that works here as well, at least that's part of the procedure. But now you see that we have many gauge fields. And I can take the gravitini and I can give them charge under any of these gauge fields. And so or the most general thing I can do is to take a linear combination with arbitrary parameters and take that gauge field and use it to charge the gravitini. So use the combination xi lambda a mu lambda to do this. Where xi lambda are arbitrary parameters, they're called, in this context, they are called faeiliopoulos terms. Actually, I'm not doing this in the canonical way. If you read the textbook on gauge supergravity, you won't hear the presentation in this way. You will start reading about potentials and superpotentials and then terms in there. I always refuse to do it in the canonical way. So I think of my own way. And so you will see later what is the connection to terms in the potential. So I can pick a general combination and I call them parameters and whether they are called faeiliopoulos terms or not is not very relevant. I pick a combination. I use that gauge field to charge the gravitini. And if you want to use a different, you can just adapt the choice of these parameters. You can set some of them to zero and then others to one. Then you just make a particular choice which gauge field that you are using to charge the gravitini. Now, once you do that, then what you have to do is change the kinetic, the covariant derivative. You have to change the covariant derivative and add, of course, a term. Well, there's the ordinary derivative, then there's the spin connection. I don't write down all these terms here. I just write the additional terms that are used in this. And here is my gauge field, at least the combination of it. And then if you go through the details, you also find that you have to, there's two gravitini and they have opposite charge. That's why there is a sigma 3. And so this is a standard term that arises when you gauge, when you give the gravitini charge. This is also sometimes called gauging the r symmetry. I don't like to use the terminology that much, but well, whatever. It's not very important. Good. So this is what you do. This is called an electric gauging because the electric charges of the gravitino are equal to g times psi lambda. These are the electric charges. Well, I have two of them. I have plus or minus e lambda because the plus sits in one eigenvalue here and the minus in the other one. And so these are the electric charges of the gravitino, gravitini. And so of course we're going to be looking for black hole solutions. And these black holes turn out to have magnetic charges. So not electric charges. The electric charges that has been tried before, they always turn out to have, I don't know if this is really a theorem that holds in the most general class of gauge super gravities. But electric charged black holes will not appear here. So now we have a situation where we have electrically charged particles and we have a magnetically charged black hole. And so you can go through the usual Dirac arguments for the quantization of charges. And so if you have a magnetically charged object somewhere and an electrically charged particle here, the Dirac quantization condition in the conventions that we're using is something like e lambda p lambda is an integer. And in fact you can also do something slightly more complicated and in fact it is done in the literature and it's also important in the black hole story. You can also do magnetic gaugings. And you can do magnetic gaugings by introducing magnetic gauge fields and parameters. This is just a side remark to make you realize that there exists such a thing as magnetically charged gauge super gravities. So with magnetic gaugings there's quite a bit of technology to understand from the super gravity point of view what these magnetic gaugings, how they look like, how that works. But you will get something like combinations of gauge fields where these are the magnetic gauge fields. There are different gauge fields from these ones. They are the magnetic the magnetic one. So let me put a tilde here. And these are new parameters here, the magnetic phi in Leopold's terms if you want. And so you can use gauge fields like this. You have to double the amount of gauge fields if you want and then you can make gravities that have both electric and magnetic charge. And then if you go through the black hole with magnetic gaugings you can also make black holes to be both charged under electric and magnetic charges.  That's the only possibility if you impose super symmetry. Yes. Yeah, yeah, yeah. I have to complete that argument. This was just a side remark. So the first step in the procedure is what we always do when we make symmetries local. We gauge something and you do the of course then the gauge transformations come into the game and the gauge transformations they form certain commutation relations with supersymmetry. And so it turns out if you want to obey the supersymmetry algebra you also have to change the supersymmetry transformations. And for instance this would be a magnetic gauge field. Yes, you can make it part if I introduce some more indices. So suppose this lambda I have to let it run for right from the start over twice the amount of values. Then half of them I consider to be electric once and half of them there's a people who know me a bit better. And the other one are going to be the magnetic gauge fields. Of course everything is subject to electromagnetic duality transformations.  And this in between leads then to combinations of this type once I start doing the gauging. In an ungauge theory you don't see the difference that much because you can always do rotations and it is semantics what you call electric and magnetic. And well here of course with the gauging that makes a little bit that makes the theory different. And so well the field strengths will look differently for the electric and the magnetic potentials etc. I'm going to explain more in detail perhaps later. I'm not going to use the magnetic gauging I just want to mention this but I suspect that maybe Alberto will use them. No you won't forget about it. Yes well that's why I precisely introduce new fields. You cannot have that with the same field there's a whole formalism to it and well this is going to lead to a too complicated discussion. You cannot do that that's why this is an A tilde if you would if you would if you'd really introduce one gauging you could not do that locally. But there's also some choice of selective form when you write it like this so that's the magnetic. I'm afraid I can only explain as well if I take a half an hour and I don't really want to do that but it is important if you want to discuss black holes that are dionic but I'm not going to do this here. No no no this is not in the book anymore so this is so the solutions that I'm going to discuss today are basically found by well there's three papers it started with Kachatory Klem and then Njaki and Dalagata wrote a paper especially also about the magnetic gaugings and then Kiril Histov who arrived today and myself we also constructed these solutions and embedded them in m-theory computed the masses and stuff like that and the entropy. Very good these all these three papers are closely related and Kachatory Klem was the first the first paper. Excuse me can you gauge more than you want? You mean like non-Abelian groups? Yes this you can do that also becomes a story by itself like what is the story about black hole physics when there's non-Abelian gauge fields present that's already a complicated story when you just do gravity and Young Mills theory. I don't know what the state of the art is in this but there are numerical solutions where where this works but it's it's all you run into problems with the no hair theorem because a black hole cannot have non-Abelian charges that's forbidden by the non no so the question is then what do the non-Abelian sectors really do on the other hand well black holes presumably are constructed by the standard model particles so yeah I can give you here this is I'm only going to consider a billion charges of this type but there is there is literature about also in super gravity about non-Abelian but the story becomes much more complicated this is already complicated are there any more questions right so forget about the magnetic gaugings we won't do it so when you do this here you also have to adapt to super symmetry transformation rules and so what you have to do is a few things but I'll focus on the Gravitino so this is d mu epsilon i it involves the spin connection there's some other fields that are already present in the ungauge theory and then there is a modification of the following type sigma 3 ij psi lambda l lambda and then gamma mu epsilon j so what do we see here and there's one new symbol here l lambda is by definition e to the k over 2 times x lambda k is the scalar potential of which this is the special scalar metric here and so you deform also the super symmetry transformation rules if you don't your algebra doesn't work anymore as a consequence of this modification here and well now you've meant now you've changed the well i've changed the action i've changed the super symmetry we'll have to recheck whether my action is invariant and the answer is the action is no longer invariant but you can make it invariant if you also add a potential and the potential looks successful i'm just going to write it down what the potential looks like and of course all these things were derived with well a lot of effort there were basically two schools or there are two schools on on on gauge super gravities perhaps one is the sort of like belgium dutch school the width and from the width and from poin and then the the italian the italian school that started with and many other people there's lots of references many people in the audience have worked also on this and so i'm just going to write down what is the result the result is that you have to also add a potential to the theory and that potential looks as follows g i j bar let me first write it down okay here's the potential well it's good that there is a potential because if we ever want to have a ds black holes in a ds there better be a potential that generates a cosmological constant so i have not explained all the symbols here here are the phyliopoulos terms here are these else there are essentially the sections x i multiplied by the kilo potential here's the inverse metric g i j and then there's this f this f is defined where can i write it perhaps here f i lambda equals e to the k over 2 di x lambda lambda lambda and this di is the derivative with respect to z the coordinate over here the x is dependent on the z and you have to covariantize this with a so right equals e to the k over 2 di plus the k log potential acting on x lambda hope you can still read this there's a lot of definitions and abbreviations all these objects have geometrical interpretations but i won't have time to explain all the beauty of the special geometry so now the model is completely defined here this is my action that's still true in the bosonic case nothing has changed because this we left uncharged so the only modifications to the Lagrangian arise because of these kind of terms and because a potential needs to be added and if you add the potential then you can check that the whole thing is invariant on the local n equals 2 supersymmetry so now we can discuss a black hole solution so so that is my short resume of gauge supergravity and one can make that more complicated if i have time left over i will say a few things by also gauging these scalars or adding hyper multiplets and and if you do that there are still the same procedures you make derivatives covariant you change the supersymmetry rules and you add more terms to the potential and that's all well understood and well under control good i wanted to stick to this particular theory with the phyliopolis terms this is also called phyliopolis gaugings and construct black hole solutions because these were the first models where bps solutions were written down and they preserved not half of the supersymmetries but only one quarter one quarter out of eight means two supercharges and so that is something slightly particular because that doesn't happen in asymptotically flat space there it's always one half and one half out of eight is four supercharges and n equals two so the models the example that was the first example of a bps black hole in ads4 with a regular horizon no naked singularity is the one quarter bps solution black hole with nv equals one you can easily generalize that and so one vector multiplet besides the gravity photon and f to be the pre-potential i wrote down before you can easily extend this by taking four vector multiplets and just write here x one x two x three x four probably that's also what alberto will be doing so keep that in mind i just do it here for having simplified notice so basically what i'm doing is i will set some charges equal to each other and so that's a truncated version from the version that you will get that you will see in alberto's talk so to make very explicit here what this coordinate z is in this case the coordinate z is simply given by x one over x zero so this is the relation how the z coordinate arises as often you also see x one is zero is z and x zero equals one not always is the coordinate z found in this way or given in this way there's choices you can do different symplectic parametrizations but this is a particular choice that i will use so before you write down the black hole solution you have to find the minimal of this or the extreme of this potential and find that there is an ads vacuum because there was no ads vacuum there's no point in finding a black hole solution but the that's rather easy and so first you find an ads for vacuum so how does that work so you have the pre potential so you can construct all these quantities here l and f that's all dictated by the pre potential and you can just write out this potential in all its gory detail it's a function of z and z bar and these size and you just extremize it and you find an ads vacuum for a constant scalar z star equals three psi zero psi one and then the value of the potential at this extrema is the cosmological constant and it's given by a minus two g squared there has to be a well there's a g squared here or i can also put it in front of g that's the coupling constant right minus two g squared over square root of three psi zero psi one cubed and if you want to go to the model that has four vector multiplets you just write here psi one psi two and psi three so this is an ads vacuum it preserves all the supersymmetries and so that's that's step step number one then um we're going to find write down the black hole solution it's going to be magnetically charged yes there's a question a okay k is the scalar potential so the scalar potential um so i wrote down this metric here g ij bar that's of course the scalar potential of the special scalar geometry and then this this and then the question is how do you construct this out of the pre-potential there is a formula that goes something like this maybe up to factors of i's and minus i'm not entirely sure minus x bar lambda f lambda so this is a function of z and z bar i don't think i wrote down this formula yesterday so okay so we're going to look for magnetically charged black holes because the attempts to find electrically charged black hole had sort of failed because they produce negative singularities at least when you do an electric gauging and so we're going to look for we're going to make an ansatz in which the in which there is no electric field and so the ansatz so the black hole well first you write the metric in a particular ansatz you write this here the s square equals yeah we use also conventions in a in a plus minus minus minus metric forgive me it's Kirill's fault but he was very good at computing with this signature i mean so we make the ansatz here i'll specify and we make the ansatz that there's no electric field and the magnetic field theta phi lambda equals p lambda over two sin theta and so we have two magnetic charges here lambda runs over one and two there's a zero and a one so we have magnetic charges p zero and p one these are the two magnetic charges there's no electric charges because i put it in there and then essentially you turn the crank and you find that well how explicit should i be u of r is equal to e to the k over two g r plus some constant that i will specify in a moment h of r is given by r e to the minus k over two so these are the functions that you plug in here u and h it's again determined in terms of the scalar potential so you have to know what is the value for the scalar field and the scalar fields are given by harmonic function x zero equals alpha zero plus beta zero over r and x one is alpha one plus beta one over r and so um so we have a bunch of constants here namely alpha zero beta zero alpha one beta one and we have this constant c they are all if you work out the the bps conditions they're all determined by the two phi a eliopolis terms and the two magnetic charges so they are all so alpha beta and this coefficient c they're all determined by xi lambda xi zero and xi one and p zero and p one i didn't write down the explicit expressions here but they're in uh in the papers that i uh quoted okay so um that's it everything is specified here well to make it very concrete you have to plug in some value because you have to compute the scalar potential you have to find the coefficient c here but uh i have not given the formula it's crucial to have a horizon because uh the the c should be negative because if c is not negative you will never find a zero of of of this and then there will be no horizon but things work out in the way that c is negative and if c is negative then everybody can solve this uh find a zero of this question then you find the value of the horizon and the value of the horizon or the location of the horizon is given by our horizon equals well it's a it's a it's actually a rather complicated formula well rather in some sense the easiest way to write it we found was um minus two g squared but i still have to eliminate this beta in terms of the phyliopolis terms and the charges and then you get a um value for the horizon and with the horizon you can compute compute the entropy and s equals a over four um i think alberto will also write that formula in a more elegant way so you can plug it in uh by you have to be it's a little bit subtle because you have to compute the function h at the value of the horizon because and that you have to integrate so it's not just r h squared yeah it's h squared at the horizon squared and that multiplied by four pi and so um that's um so that is the that is the result um some remarks well the near horizon geometry just like for asymptotically flat black holes is again given by an ads two cross s two factor near horizon that's of course very important that we have uh in the infrared also conformal symmetry dictated by the ads two factor the only difference with asymptotically flat space time is that the radii of of these two spaces are not equal to each other but that doesn't bother us too much so another remark is that we can also construct i mentioned this very quickly in that we can construct a black hole with an electric and a magnetic charge not in the theory and in the gauging that i wrote down um with let's say a magnetic charge with respect to the first gauge field and an electric charge with respect to the second um but then you have to use electromagnetic or symplectic transformations i didn't explain that well but apparently it's also not going to be needed what you do then is you have to act with that on the full theory then also the pre-potential that's not invariant under these transformations if you choose equals to x one cubed over x zero then of course also the gravitini are going to have different charges they're going to have one electric charge and one magnetic charge engage with gravity you cannot there's no invariance on the disimplific transformation because i is there's an object that i can see this is the absorption um there's there's covariance but not invariance um well i i wrote down the potential for instance uh and this potential has phi a heliopolis term and so that is not invariant these these phi a heliopolis terms they they they also have some index lambda if you want and on that index lambda electromagnetic duality transformation or symplectic transformation they act on anything that has a lambda index but then you see already that there is a there is a its partner is missing so we have symplectic pairs this is a little bit of an aside x lambda and f lambda this is a symplectic pair but also the phi a heliopolis terms xi lambda um there will be xi lambda and xi lambda and these will these will generate electric gaugings and these will generate magnetic gaugings and so um one of them was missing uh i only had in my potential i only had since i was doing electric gauging the other one was not there and so the theory is not invariant under these transformers there's many ways of saying the same thing also the kinetic terms for the scalar fields without gauging it's not invariant it's only invariant if you also change the pre-potential therefore it's not invariant but it has some covariance properties if you also change the pre-potential then the Lagrangian state has still the same form except that you have to change uh take a different expression for the pre-potential so in the potential you clearly see that some terms are missing and in fact if you people constructed the magnetic gaugings in a way such that this covariance properties become um become uh well actually have the expression on the next slide um no it's not scalar transformations it's electromagnetic transformations so you basically rotate also so um so another symplectic pair is f mu nu lambda and then we have g mu nu lambda which you can think of as the magnetic field strength think of it as just the star of f and so symplectic transformations also act on this pair and so there you see that you're basically changing electric and magnetic fields so that's that's the way to think of it physically yes yes yeah yeah yes that's right yes it's a supersymmetric solution by its own and I think um you'll help me if I'm wrong but I think if you just the near horizon the solution is is again maximum is is sorry has augmented supersymmetry and that is one half bps uh is that correct yes yeah yeah yeah so so that we've seen also in flat space so if you have a black hole asymptotically flat space maximal supersymmetry then along the way to the horizon you break half of it but at the horizon you have again maximal supersymmetry with ads it's a little bit different there also at asymptotically flat so you have maximal supersymmetry along the flow it has one quarter and at the horizon it is bps but it's one half not not maximal but one half very good yes uh can you speak a bit louder yes yes yes and there's also an attractor mechanism going on it's a little bit more complicated but in this example it's very easy because we see that z the coordinate z is the ratio of this two and it's the same story since b well now uh now the the attractor mechanism and the no hair theorem says that the black hole horizon should be determined in terms of the charges only and it's going to be the charges of the black hole but also the phi a heliopolis terms but these are charges because there are electric charges of the of the gravitini and so there's an attractor equation as well the only thing you have to be careful with is that if there is flat directions in your potential there are some scalar fields that don't see the black hole those of course are not fixed by attractor that they're just you can set them to constant at any constant very good um there's an m theory lift that's important of course um that's important um to make the connection with ads cft so the story is that um this can be embedded by uh in m theory using the spherical compactification of course you get a more complicated n equals h supergravity the details are in the dove u paper um already from uh 99 i think huh yeah so or something like that um that is you huh isn't it yeah that is you you yes yeah so very good um so the details of it uh are important for uh making contact with ads cft and so here you get of course so eight gaugings here you see an example where you have non-habilian gauging but what you do is you make a constructed black hole uh the so eight has a carton which is you want to the fourth there you see your four vector multiplets coming out all the non-habilian stuff you you you truncate or that by this i mean you construct a black hole solution that's only charged with respect to the you want to the fourth and so you will get uh charges p zero p one p two and p three um and um um well of course i would need to write it out and exactly go through the truncation but uh i want to have time for that um very good so let me just mention since i have 10 minutes still time about uh the the broader class of gaugings such that you get a little bit of a total overview so after the kachatory clem and our papers um people investigated extensions generalizations um to include also hyper multiplets or other gaugings and um that is still very much ongoing there are some results some of them are numerical many people in the audience here have worked on it i'm not going to give all the names but um and sometimes people could also only construct the near horizon solution so the eddy has two crosses two solutions and in only very particular cases one could find analytic solutions uh where more general gaugings were considered so let me say a few words because i still have 10 minutes about these more uh complicated gauging so so we can also so one was a gauging of the gravitini or called also called r symmetry gauging and so we can gauge gauge the or charge the vector multiplet scalars and so well for this every time you gauge something you must have a global symmetry first now the scalar fields in the Lagrangian have the following form kinetic term so you must have a global symmetry first but here you have a non-linear sigma model so that means that this this you will never have a global symmetry if there is no killing vectors or symmetries associated to this metric so you need what is called a killing a killing vector and or or a bunch of killing vectors and then you can have a global gauge symmetry acting on the scalar fields alpha lambda k lambda i which is a function of z and these are killing vectors vectors of of the metric g i j bar so they satisfy the killing equation once you have this you have a global symmetry you can gauge it and so you change d mu z i into d a covariant derivative which is just and of course there is a well the gauge transformation now there is a covariant and so you've gauged this symmetry but that doesn't that's not enough you have to also change the supersymmetry transformation rules and you also have to then change the potential i will write down the potential in a moment because well now that this is kind of a clear procedure you can also of course gauge the hypermultiplet scalars and of course you can do a combination of everything yes the most general gauging and the most general gauge supergravity gauges everything the gravitini the vector multiplet scalars and the hypermultiplet scalars so here we have a kinetic term which is something like well how did i write it down yesterday g u or it's called h u v in the notation of some of our papers d mu q u so they're called q u u equals 1 to 4 n this is quaternionic geometry this is the metric on the quaternionic geometry you again need same story as there you need well what shall we call it well you can use the same parameters of course because there's only one type of gauge so lambda we can have killing vectors in the quaternionic geometry and so call them q tilde so these are killing vectors of h u v and so then of course you do the same thing you construct a covariant derivative d mu q u consisting of the ordinary derivative plus g a mu lambda and k tilde lambda u function of q so they're the same vectors we use the vector we use the gauge fields from the vector multiplets to charge either the scalars that sits in their own in their own multiplet or you use them to charge the scalars that sit in another multiplet so this amu and that amu is just the same there's only one set of gauge fields that are present so then you have to adapt to supersymmetry transformation rules and to close the or to make the algebra closing on shell here we're on shell and once the supersymmetry transformation rules are modified you have to start varying the action you find is not invariant unless you also add a potential and the potential i'm going to write it down is a function of z z bar and q i'm only doing electric gauges here and so here's g square g i j bar k i lambda k j bar sigma plus four h u v that's the last formula i will write down so okay let me so let's say a few things about it so in the previous case where i only had the the r symmetry gauges there was no killing vectors here so this this term was not here i don't know hyper multiplet this term was completely absent this term was completely absent the only thing that i had basically was this term and these p's were then the phyliopolis terms now generically these p's are called moment maps i would need to tell a little bit of geometry to explain what moment maps are but in some sense the simplest choice of these moment maps are setting them to a constant and those are then and those are two vectors and you can wrote it put them in one direction and that these are called the phyliopolis terms so that reproduces the reproduces the potential that i wrote down before this term was absent and this term you see there's a computation between positive terms and negative terms because here we have the minus sign so that allows for vacua either decider anti-decider minkowski there's a balancing between positive and negative terms in contrast to supersymmetric field theories where potentials are always positive and so well that's it so the the the the the the the story here about this potential is that it's it is a completely geometrical interpretation it's a function of all the scalar fields both in the vector multiplets and the hyper multiplets and it's determined by geometrical data the pre-potential on the Keeler potential it's killing vectors so it's symmetries same for the hyper multiplets it's the metric and and it's killing vectors these else i wrote down before it was e to the k over two times x and x where this is all determined by the pre-potential same story here determined by the pre-potential and these are moment maps moment maps are basically constructed out of the out of the killing vectors on the hyper Keeler space so i'm not going to bother you with the details of these moment maps but it's something explicitly constructed in terms of killing of these killing vectors so then in principle that you can start playing the same game you can look for bps for bps bps black hole solution and that story is very much going on there's not too many examples of black hole solution maybe maybe there's even only one i think where there's an analytic solution known with with hyper multiplets present and so that's still under development i i'm also not up to date with the very latest so people can inform me here if i'm overlooking something clearly it's the the story is to find more general black hole solutions just rather than just having that singular example i just found find a generic structure of the solutions find the embedding in string theory or in amp theory they must asymptote to ads4 well we want them that's that's the the goal of this whole exercise because we want to explain the entropy of black holes using the dual field theory which was successfully done in the example that i showed in the paper by francesco alberto kiril uh so i think we're going to hear more about it in alberto's lecture so i will stop here the timing seems to be perfect so thank you for


Welcome to the Knuckleheads of Liberty. It seems like those accusing of misinformation are often the ones generating the misinformation. And case in point, we talked about it last time on Knuckleheads of Liberty, excuse me, on our Knucklehead noise patrol last time. And it had to do with Biden and his redefining, we're trying to redefine on the fly what a recession is. You know, two quarters of negative growth has always been the accepted definition and it's even been used by Biden himself in pointing at Trump when Trump was president. So I mean, this is nothing new and suddenly because this is very, it's an inconvenient truth for the Biden administration that he's in a recession when so many people thought that things would be in a bit of a boom for him coming out of COVID. Now he is literally just trying to, you know, kind of say the dog ate his homework or something. He's trying to say that, well, well, it depends upon what you call a recession. So maybe we could get the visual up there. So the White House spokesperson literally just as she won't define what a woman is, she won't define what a recession is. Either she just says, I know we're not in one, but she, when pressed, she literally refuses to define what a recession is and then cites other sources to go ask them. I mean, mostly this National Bureau of Economic Research, the Inver, is what she's referring to, which is a government entity. So anyways, we're going to jump into a few more issues on that. But let me kick it over to you guys right away. What do you guys think about that? I mean, this is just absolute lunacy. You know, you don't like the argument. You just change the words on the fly so that you don't have to confront the argument. Yeah, let's listen to what the NBER says in their Q&A section when the question is, what indicators does the committee use, talking about NBER, the committee she says they go by, to determine peak and trough dates. OK, so these are the dates that when, you know, when a recession occurs, if you're going to have one, or a trough in the economic activity. So they talk about the determination of them is based on a range of monthly measures of aggregate real economic activity published by federal statistical agencies. Then they go through a list of a few of them, you know, things like payroll and non-farm payroll employment, personal consumption, so on and so forth. The last sentence says it all. And I read to you, quote, there is no fixed rule about what measures contribute information to the process or how they are weighed in our decisions. So essentially, they just make it up as they go along. So the NBER, this agency, I guess a federal government agency, probably paid for by taxpayer money, I'm assuming, is just totally winging it. They have no basic. I mean, if you can't come up with a date of the trough, then how do you know when the recession began or ended? Correct? Right? If you have no rule, no, and they admit they have no rules about how to determine that. Well, Tim, it sounds very much like this is saying, look, we're the shepherds. We're not going to give you sheep any objective measures to think for yourself. Just just have faith in what we're telling us. Trust us. Yeah, this is this is religion. Trust us. Yes. Yes. Yeah. You know, Tim, that information that you just read, is that recent wordage? Or was that there previously? Previous to this whole controversy? This was this particular, yeah, it was I can't remember the month, but it was in twenty twenty one because they were given examples of twenty twenty and, you know, basically examples of how they basically had nothing to say. So then if you read the whole thing, every word that all they're saying is that they have nothing to say, you know, basically, because they have no criteria whatsoever. But it was in twenty twenty one. It was not recent. It was not like, oh, they came up with this because of Biden. They've always they've always I think Biden just wanted to use them because they had no standards and they admit they have no. They have no rules by which they determine dates of a of a trough or a peak in economic activity. No, none. Nothing. So basically, they're free to call whatever they want, a trough and call it a peak. Maybe the peak is a trough and the trough is a peak. They don't know who they have those who they have those. So which which which relates raises the question, the very interesting question. If the N and NERB, I think is what NBR, NBR, yeah, if they don't know when whether we have an recession or not and the administration is saying that we are not in a in a recession, how the hell do they know that? The people that they are sending us to, they're telling us to go talk to these people. They don't have anything to tell us where we are in a recession or not in a recession. But the Biden administration who are using these people as their source is telling us we are not in a we are not in a recession.  Well, well, yeah, I mean, I can't think of a bigger, better agency to send people to for a definition when the agency itself has no definition. I mean, wouldn't you send them to there to that agency if you didn't want a definition for for a recession because you don't want to be pinned down as having been presiding as president over a recession. Well, of course, you want to send them to some place that has zero rules by which to establish when a recession occurs. Well, I'm just going to say it sounds very much like post hoc storytelling.  Exactly. Exactly. And it's quite interesting to see the media, OK, and big tech and left wing economists doing everything they can to protect the Biden administration. Paul Kogman saying, no, it doesn't matter. We are not in a recession. Life, liberty and the pursuit of happiness always and forever.


It's been an exciting 10 years. The thing about it is when we first came up with the idea, it was really just an opportunity to do a couple things. Number one, to introduce or support children's love of reading. Number two, it was to get community volunteers into our school district. And then three, we also wanted to support South Carolina either by choosing books that are by South Carolina authors or books that are about South Carolina, sometimes Columbia specifically. So it was really a threefold mission and it's been exciting over the last 10 years to see how it's evolved and how the students and the volunteers look forward to it every single year. If we can give that mastery and that love of reading to children, we know that everything comes back to children. Our children are not just our future, they're our present. I mean it's ever rapidly changing world, technological advancements. You have to learn to read and then obviously you read to learn and together we can work and make the city of our children deserve. To see the bright eyes light up and be able to share with them rich parts of our history through the books that we read, it's an amazing contribution. Our students love to read and I think the relationship that is developed between our readers and our students at that elementary level, it not only creates a bond for them but it also creates a love for learning. I think what it does is it sends a message that our students realize that they're not in this alone. The children are inspired that they can really go anywhere they want to and it starts with opening a book and they can become lifelong learners and that by reading it will help open as many doors as they want. By not reading those doors stay closed but reading is fundamental to a person's ability to be successful in life. I'm always impressed to observe the degree of comprehension of the children. They are very smart. They hold your attention. You don't hold their attention. It allows them also to demonstrate their reading skills, their comprehension skills, their ability to be creative about subject matters and I'm always impressed with that. Even more important than reading was just sharing with them who I am, where I work, where I'm from and when I typically share with them that I'm from this community and the community that they're from, they tend to be inspired by that. The reality is that when you're trying to raise good, solid, well-rounded citizens, it's not just the responsibility of the schools. It's civic leaders, it's neighborhood leaders, it's parents, it's church leaders. We're in this together and bringing community leaders into the school to recognize that we have to build a complete, totally supportive environment in which our children can grow up to the God-given potential that's underscored by programs like this. It's not just the four corners of the schools and the great professionals inside them. All of us have that responsibility and together we can read helps underscore that every year. The impact that reading in the schools have had on the community leaders I think has far exceeded what my expectations were because we've got community leaders who have gotten their companies involved in adopting a school and volunteering, being lunch buddies. We've had community leaders who have donated not only of their time but money and resources to help the schools what they've gone in and see the great things. I don't know if we can do anything any more important than inspiring young people on a lifelong journey of learning and gaining wisdom. And I don't know if anything else that we can do is any more important than getting people who don't spend time in schools to come in and spend 30 minutes or an hour reading and talking to children. It's a great opportunity to see what all the wonderful things that the educators and the parents in the community at large do with and for children. It's also important for them to see how gifted and how creative and how fun it how precious our children are because they are our future. This is one of the most rewarding experiences that they can ever be a part of. Our kids, our children are precious. And that one-on-one time with them means so much to them but for you as the reader, it's so fulfilling to have that one-on-one time with our students. Partnering with the City of Columbia, with the local school district is just a good thing to do. We know that organizations that partner tend to do better and whatever their mission and their vision and their goals are. And when the two entities that are so important to the viability of the City of Columbia partner, it's a really good thing. And especially when it's about children and particularly children reading. I've always been to the most powerful words in the English language are thank you. I want to say thank you to the hundreds of volunteers when they've committed their time. There are probably thousands of volunteers committed their time over the last decade to make sure our children understand the power of reading and the importance of reading and the importance of community. The future is bright. Together we can read. I can see it being just as impactful and just as successful as it's been for the past 10 years. Just looking back over the 10 years, seeing how many opportunities we've been able to provide for our students within District 1 has been extraordinary. And then again to hear from some of them, you know, some of the first students that we had are now in college. And they remember the people who came to their school and came and read. So that to me is it shows a lasting legacy of this program. And so that's humbling because it's just started off as an idea. When we took a trip to look at another school district and what they were doing there and and to see that idea blossom into something like this is just really humbling.


So good afternoon, everyone, myself Prashanjit, this is Vaibhav and Aditya, we are here for presenting IIT BombEx Android app development that is in FHG. So we'll be covering topics like introduction to what features we have added. So basically Open edX app is already available for Android devices and IIT BombEx is just an instance of Open edX. So we have used that to customize it according to the requirements of IIT BombEx. Now what are the requirements? These are the requirements incorporation of the four types of MOOCs that we have on IIT BombEx. So to do that, but to incorporate that, we have to do some very basic changes like someone has to enroll successfully, someone can comment successfully, all these features need to be functional. So these changes that we have made are very first step towards a fully functional app. Now the motivation is obviously an app, in an app delivery of content is easy and we also have to incorporate course discovery. Course discovery is just a page which shows the list of courses available and features associated with course discovery like searching, then course enrollment features associated with course components like being able to view a course, like a video. So then we also have to do some server side configurations for app to incorporate the needed changes. These changes can be translated to IIT BombEx server because we have done these changes in Open edX like a local instance. Now the technology is obviously used at Django and on client-side it is Android because Open edX is based on Django. So IIT BombEx is running on Fikers version as mentioned before and our local instance is based on Ironwood. Now we worked on an app that targets Ironwood because we didn't target Fikers version because everyone is shifting to Ironwood. So IIT BombEx also has to shift sometime otherwise it will be left behind. So we directly went with an app for Ironwood and even if we try to use it with Fikers we can't use it because it doesn't have backward compatibility because of API versioning. Fikers uses some version 0.5 while Ironwood uses version 1 of APIs. We'll look into that. Now our minimum API level of Android should be KitKat and maximum should be Oreo. Like it has been tested till Oreo. It hasn't been tested on P but we have tried it and it worked. So moving on, this is the mobile-centric architecture from the app point of view. It is connected to the LMS and discussion forum. Now LMS takes the courses from MongoDB and in CMS you can create courses which are stored in MongoDB and if there is a user who logs in in LMS his data is stored in MySQL even the comments and posts are stored in MongoDB. So we put this here because this is where most of our work is centered around. So and there are two files named CMS.env.json and LMS.env.json. These control how LMS and CMS behave. These are two server-side files. They contain environment variables which can be said to true or false and the behavior of LMS and CMS will be decided. So first we have needed a local instance obviously. It can be done in at least following two ways, DevStack or DevStack-based or native-based. DevStack-based services are containerized in 15 containers because we found there were 15 services. It is faster to set up the native for development purposes but we didn't use it because it uses Django run server as mentioned by Sir which does not have keep alive header. So we face an error while running the app. So we went for native-based where services are installed on native OS which uses InginX which supports keep alive header. So we connected the app to native-based local instance. Now there are two components which app uses from edX that is OAuth2 and edX REST API service. Now we are aware of what OAuth2 is. It basically authenticates a client to be able to use this REST API service. Now this edX has already provided us with a list of APIs like to access discussions, to make, to comment what are the course enrollments for a particular user. The behavior of these two files as specified before is also controlled by two flags named enable OAuth2 provider in LMS.inv.json and for REST API enable REST API provider in LMS.inv.json. Because the app has a web view which shows the courses from LMS, we have only shown the flags for LMS. We haven't gone to CMS as of now. Now Adita will mention this. So after setting up the server the main task was to connect app with the server. This can be done by logging into the open edX server through admin and creating a client. So client can be created by giving parameters such as app name and redirect URL which is provided by open edX. While creating the client ID and a client secret is generated. So client secret is written within the server. There is a file called config.yml on the android side that is the client side which contains environment variables for the client. So we have to add this client ID into the android code into the config.yml file. So this flow shows the communication between app and server for a specific user. This contains a chain of requests and responses. User credentials are taken to the over to server. Over to server verifies if the user is authenticated or not and it provides with a bearer token that is access token. For any further request this access token is attached to the header of the request so that server does not need to verify the user again and again. So this access token get request is done to the domain slash api slash mobile slash v0.5 with this access token and it responds with user details such as user name and all details of the user. Using this user name a get request is done to api slash mobile and it responds with all the list of courses which the user has enrolled in. By getting all these details a discovery page is showed to the user. Discovery page is list of courses which user can enroll in. These are the main features that we have worked upon. First is customization of templates, then achieving single sign in integration of search functionality and enabling in-app u2 player. So customization of template. As we all know the templates are already present on the server side and we can access through a web browser. So what android does it? It does not have a separate code to show the list of courses directly on the android code. What is does it? It takes the web page and shows, displays it in the android native view. It is called a web view. So as you can see it contains unnecessary features like header, footer and search bar that we do not need in the android app. The android app contains search feature on it's own so we don't want this website search bar. So we have to customize the template. What we did was we did not change directly the main files. We replicated that file and added the changes we made to that file. The main templates that we worked upon were course discovery and course about. So what's course discovery? Course discovery is a page that shows list of all courses and course about is a page that shows details about a specific course. So with the changes we made was removing header, footer and search bar and reducing the padding. So when these changes were made the link to URL pattern was added in urls.py file on the server side. As you can see the changes made before and after. Before making the changes app shows the header, footer and search bar and after we removed this the app looks like that. Okay so coming to the another important functionality that we have worked upon it is a single silent feature. So the problem was now we had to enroll in the app and the discovery page in which we enroll actually it was in the web view. But the courses page which displays all the courses that any user has been enrolled that is in native. So the thing is if a user has already logged in in native then it should not be that the same user has to log in again while enrolling. So what we had to do was just skip the single sign in page which appears in web view. So we found that there are two to three ways for doing so but we have proceeded through deep links. I will tell in short that we have not used URL interceptor because like it intercepts the request in the header but the actual problem is after that procedure if we do anything like for discussions or notifications everything will be in web view which we definitely do not want. Next is Chrome custom tabs this is a feature for cookie and session management but it is only limited to Google Chrome and not for other web browsers. So that's the limitation. Next deep links which we have worked upon these are actually the links that can substitute the hyperlinks like for example the discovery pages there where there are different course styles. So when I click upon it the course info page will be generated and there the enrol button is present which actually contains the deep link for example for edx app the syntax will be like edx app colon slash slash enrol question mark course id and some course which will be different for every course. By this we can immediately skip the sign in page which appears while enrolling and this is just a pictorial representation like I have just explained from domain slash mobile web view. This is the course info deep link which is present in the course style and after that when we click on the enrol button the dashboard native page will be generated. So coming to another important function which is search so we all know that if there are many many courses then it becomes very necessary for enabling this feature. It can be done easily by setting these two flags which are enable courseware index and enable course discovery in cms.earby.json and lms.earby.json files but the actual problem we faced here was that the search function works easily for whenever we search for one time. So see like here the domain slash only domain slash mobile web view page when we search for a particular course the base URL is changed to domain slash mobile web view and the search query equal to test course is added but next time we search for any other course the initially the code was taking this complete existing URL as the base URL but what we needed was only domain slash mobile web view as the base URL so this was added in the code. Then finally for embedding a youtube support in our app we actually added this flag that is in-app youtube player inside the config.viable file. In this case the ordering of video fragments is very important. For example there is a class which is course.earby.json adapter. It actually takes for example if any video whether it is downloaded in the app or not. If it is downloaded then it will ask whether if it is not downloaded then simply it will ask that do you want to play it on youtube or web browser but if it is downloaded and then it will check whether the flag is enabled and if it retrieves the youtube player only then that video can be viewed inside the app. Next coming to future scope of this project so there are some functionalities which can be definitely added like unenrolled button for unenrolling through the app and then autocomplete feature while searching. Similarly for discussion and notifications it like actually currently we were facing some problems on server side while posting in discussion forums that is we could post but the response or comment feature was it could not be done as of now but this can be definitely done in the coming future and for push notifications the thing is there was a parse server which was used by edX few years back but it is deprecated now so we are in search of some open source feature like we have looked up on cloud messaging but in case if we get some open source alternative then nothing better than that finally some documentation references that's all thank you. In the presentation you have mentioned that you are using native app and web view why? An app that uses both native pages and web view it combination so that it can load courses from already existing server using the APIs and we can enroll and go to the native page because native page offers more functionalities like viewing the videos. So this is what I wanted to see I have seen that application but never tried because they are using web views so I wanted those all web views to be replaced by native application. That's why the use of web views in this case is only limited to two things that is viewing the details of that course and viewing the list of that course that is but that is the most important thing for a student like if you do it in native you are doing nothing new you are just again showing the list of courses in web view we are showing the list of courses if you do that in it do you have any screenshot yeah can you please show the screenshot offer a course unit page you showed that was not from so you also mentioned that somebody is downloading youtube videos the videos correct so how they are downloading downloading in youtube app or downloading as a mp4 file in your mobile or how you tell me just tell me I just want to know so somebody is downloading youtube videos which are there in the course correct so they are downloading how the youtube download feature offline safe feature is there like in the app there is a feature like we can download any video in which app you know so when you somebody clicks on download what happens the mp4 file saved or youtube offline no sir the files get downloaded file downloaded here but we are embedding only youtube's link there in the courses then how mp4 is downloading no sir but actually the thing is like we have tried the playing video in the apps so right so initially it was coming that this video can be played only in youtube correct because because of web view you know so this is why I am saying why using web view use native no net yes no sir once you enroll in a course control shifts back to native and anything that is viewing the course videos commenting those are all in native okay so the problem was if you were trying to view a video it was redirecting to youtube app so we didn't want that we wanted the video to show inside the yes yes so that's why there was only a we only found a flag we had to set that flag and that that's okay so now video is playing in native mode via youtube correct but when somebody clicks on download you are saying that you are saving dot mp4 file in users mobile that those videos are have already been uploaded in cms by like when while creating a course inside a course component no no we don't we don't upload mp4 files we upload only if you are uploading anything in cms then that can be shown in app if you if there's a youtube link then that will play inside the native app so we just wanted the video to play in app the link will be embedded but if somebody is clicking on download what happens the offline download feature of youtube no no in your application there is a possibility to download the video you said no okay so somebody clicks on that what happens sir actually we have not tested that you that feature was initially present for downloading okay you did not develop it it was there okay we didn't hide it okay and how are you managing youtube sorry account the session management how you are doing it once you're logging in through the native pages so it's automatically app is storing it it's like caching okay and it is basically this is the problem however we can't make web application separately no no right now what is happening in the mobile application somebody is logging in yeah so then token is there in the mobile devices but what I want I wanted to make a web application which is which need not to be on the super domain of open edx getting me right now it's does that that link is mandatory so I wanted yeah separate is required okay thank you


No, okay. What's up this week lady Ada? Okay first up. We've got a 1 millimeter 26 pin FPC cable. I'm gonna be using this for some floppy stuff. So just hold on tight to this You know came in before the floppy stuff did But that's what we use it for it's floppy disks floppy disk drives used in laptops use this cable and I wanted an extra Next up. We have a gorgeous even the people who are fabricating it. We're like this is a really good-looking TFT screen. It's a 1.47 inch 172 by 320 pixel IPS display using the very popular and well-supported ST 7789 chipset It's a very easy to wire up and use whether Arduino circuit Python libraries You just set the resolution to 172 by 320 and it's you know extremely high PPS pixels per square inch. I think it's 220 just I think the the highest density we've got Very close to the 1.3 and on the back. It's also got an iSpy connector So you can use it with a breadboard with the breakout pads can be used with three or five volt logic and power Has a micro SD card slot if you want to store images or animations on it as well and share with the SPI port And then the iSpy connector makes it very easy for you to wire it up if you want to put the display far away So a lovely little display will have its big sister the 1.9 inch in the store shortly All right. Did you want to show it off? Yes, I can show it off Get real close because it's real small. Yeah, I like that we have really good photos of our stuff However, I do like that. We were able to always do live demos of our stuff because I feel like that That means it actually is kind of easy to use of life It doesn't mean something a little different Because you could see it turned on like yeah, you know stuff over video cameras and web cameras and all that So it's very beautiful it's got that round wrecked.  Yeah, so that's how it works. Okay, so anyways, so here's the beautiful photos are all good We have we love our beautiful photos, but I'd like to like demonstrate. Okay, next up Okay, next up we have a new time of flight sensor. That's the TOF sensor for the code Which can get 10% off this sensor if you're watching this live. This is a new time of flight sensor from ST This sensor they you know, they've done the VL 6180 and then they went to the VL 53 L 0x and then the 53 L 1x and those got up to like four meter distance This one is a shorter meter distance. This is 1.3 meters distance But it's good for closer up according to the day sheet It can do as little as one meter one millimeter away So it's good for closer measurements Because I can you know the other sensors kind of can't do less than one inch or one and a half inches away And this one can do less than that And it's got Arduino library support right now. We'll be working on circuit Python library support So if the text description says it's got it by the time you watch this video it does but as you know This chip just came out and we got it real fast into the store Using the Arduino library and thought I could show it as well Another live demo. Yeah, and you can see the little sensor. It's kind of nice and you can see it's Got me moving up and down That works, huh? That works. It does work and it doesn't display if I'm too far away. So A still time of flight sensor, you know, I think this one is good if you just need Closer measurements, you know, if you don't need up to four meters If you only need one and one and a quarter meters away Then this one will do the job very well.  It looks gorgeous And if you order them now, that's what you'll get. Yeah, so thank you everyone who's said more pink boards Pink pink pink. You said it we listen and then 2040 last week this week the feather All right, and then the star of the show tonight besides you lady or community Our customers are staff running things behind the scenes and more is the new feather ESP 32 V2 this is a really big fresh upgrade to the feather ESP 32 one of our most popular feathers Because of the chip shortage, I can't get CP 2104s anymore. That's the USB serial chip And so I have to update to the CP 2102 Which has a slightly different schematic usage And so it was like well I got to go fix that up to revise this board so I can keep manufacturing it and then before you know it I kind of like Remodeled the whole thing so the whole board has gotten like a huge update Which is great. So let's just stop here because I can I can point at it while it's nice and big On the right there used to be a war room module, and that's the Pico module The Pico module is an ESP 32 with eight megabytes of flash and two megabytes of psram So that's twice the amount of flash and then extra psram that was not available on the original ESP 32 That's super handy if you're buffering data or you just want like You want to have a camera interface or a buffer a display output? Read large JSON files parse them that psram is so handy and the the ESP IDF and Arduino is natively just you know map that memory in and so you can use it It's not as fast as the SRAM, but it's great for again large data buffering To lower left of that there is a new neopixel on it the ESP 32 did not have a neopixel now it does And the power pin is on another GPIO so you can go into low power usage, and that's another thing We really optimize this feather for better low power support so the Neopixel can be turned off and then there's a separate LDO right above it for the Stem aqt connector that's the kind of yellow forpin connector above that you can get down to 70 microamps of power draw while in deep sleep for the ESP 32, which is pretty good because You know you can wake up from deep sleep with the RTC on at any timer interval you'd like The Stem aqt port is also new on there It's a vertical port and allows you to connect You know any of our dozens of Stem aqt or you can use a grove adapter to connect grove I squirt see sensors or from spark fun. They're quick sensors or there's a lot of companies now making Sensors with this adapter cable, so it's plug-and-play no soldering required and you can turn off power separately to this port again with that GPIO pin there is the USB serial converter, which is now updated to a CP 2102 it can now do three megabits There's also an extra tactile button on pin 38 And the USB has been updated from micro B to USB C so you can see like a lot of new stuff It's pretty much pin compatible with the original feather ESP 32 All the all the numbers are on the back the named pins like SDA SCL Mosey miso as clock a tx and rx those did change the underlying pin number because In order to get the ps ram, you know one pin disappeared and one once one pin disappears it can't turn into this You know every pin has to sort of change and so the numbered pens didn't change and the analog pins didn't change But the named I squared see SPI in your pens did change So just in your code you'll have to recompile it Which will need to anyway to take advantage of the extra flash and ps ram actually have to select the new board support package Just make sure you use the the words like mosey miso SDA SCL rx tx and that won't automatically translate into the numbers don't use the underlying like pin seven names for it But otherwise this should work drop in with pretty much any of your feather ESP 32 projects And it's just a big upgrade around the you know just everything got upgraded and updated It's so much better more pin labels on the top. So I'm really psyched to release this more mounting holes So good feather ESP 32