Hello everybody. So, today we are going to talk of the some other new consequence as well in the sense that new to our course of course of special relativity. We are going to talk of mass energy and momentum in special relativity. I suppose remember how mass was varying with velocity right. So, unlike in classical mechanics where you know if you whatever the mass of a body is if you move if the body moves its mass does not change. But here of course we have this concept of what a rest mass is and the fact that you are in a frame which is moving with some you know some uniform velocity with something else and in a sense the mass itself is moving with certain velocity then you do find the mass of the body has changed. Well we did see some consequences of that today what we are going to do is relate this the relate the mass that is to the total energy and also with the momentum. Now, having said talked of mass and energy I mean it is very certain that we are going to talk of E is equal to m c squared. We are going to spend some time to see how this comes about it is I suppose one of the most well known equations in physics anybody who has even opened a textbook in physics or about read about scientists and what physics is has heard about this equation. So, today what we are going to do is to see a simple way how to derive this from principles which are known to us. So, first you know let us consider a force which is being applied to body and when this force acts what happens is that it displaces the body by an amount by a small amount d x let us say in time d t. So, the small displacement d x and that too in the direction of the force y. So, if you take the dot product you know if you just take you do not need to take the vector part in such f d x and then it also happens in some small time d t. So, what happens I mean what happens when one applies this force well body starts moving I mean if the body was initially at rest and then after the application of the force it retains velocity v let us say small v then what would be the total gain in the kinetic energy of the body well by definition it is the work done is not it I mean. So, that is the energy that the kinetic energy that the body has gained once it reaches a final velocity v from its initial rest position what is that. So, that is integration of f d x of course, well you know in a proper sense one should have taken the vector f dot t x but as we said the displacement is in a direction of the force. So, it hardly matters here. Now, interesting point here is that we write this force now in terms of the rate of change of momentum just see the region next to f d x and you see that it is under the integral sign you have d p d t. So, that p being the momentum gained and d x is the displacement anyway. So, how do you write this momentum you know that momentum is the mass times the velocity. So, we write d of d t of m v and then for d x we just write v d t now why is that. So, you know v being the velocity of the body that is equal to d x by d t and then we have just replaced d x as v d t right. So, how does I mean what does the equation for the expression for the kinetic energy boils down to well it is as we said I mean we are finding the gain in kinetic energy when the particle is you know from has moved from its rest position to its and has attained the final velocity v it is the integral within the limits 0 to v v being the final velocity gained and in the integrand is v of d of m v. Now, check that here we have not talked of whether m is constant or not. So, this form of the kinetic energy is very standard. We can use it for example, let us why do not we use it to find the non relativistic non relativistic expression for the kinetic energy that will clarify the situation a bit. So, for the non relativistic case what do we do here we know that you know mass of a body is constant I mean it is a fixed thing. So, we can take it out of the differential d of m v take it out of the integral sign. So, that the integration of for the kinetic energy is simply v d v and then from 0 to the final velocity detain.   So, of course, what have we done here we have taken mass to be a constant thing. So, as expected now what happens to the relativistic case in the relativistic case remember that the mass is indeed a function of velocity. So, if the mass of course, moves if the body moves with a certain velocity with a large velocity we do see actually you know large is compared to what I mean if it is of course, all velocities we are we will be considering is less than the speed of light. But then if it is approaching the speed of light we do see that the mass has increased by a lot. Of course, I mean when very low speeds it does not matter we are still in the non relativistic limit. But then we have appreciable speeds then we do start feeling that the mass of the body has increased. So, what happens if we consider that. So, the mass of a body being a function of a velocity now then we can no longer take the mass of the m out of the differential and then we have to use the entire thing. Now what would be the expression you are going to put in the exact value of the momentum or the exact value of the mass here that is m 0 divided by root over of 1 minus v square by c square of course, the v is there. So, the kinetic and what is m 0 here m 0 is the rest mass that is the mass of the body that is measured when the body is at rest. So, what is the expression for the kinetic energy then well it is v times d of m 0 v divided by root over of 1 minus v square by c square. Now this might look like a bit complicated, but we do have a thing called integration by parts in mathematics and so I think it is a proper case to utilize such a trick. So, what is this integration by parts. So, it is that if you have an integration of x dy and then you can write this as you know and then y is some complicated function that you have. So, it is nothing but x y minus of integral of y dx. Now what we do is that we identify x as the velocity here and then for y we take you know it is m times that is the momentum.  So, let us just do this integration and then get the result. If you are interested in the algebra of it I am going to spend one more slide on it. So, just to show you some of the steps. So, one or two slides that is. So, the integration that we are going to do is one written at the bottom of your screen. So, that is the expression for the relativistic case when mass is a function of velocity. So, the kinetic energy happens to be m 0 v square divided by 1 minus v square by c square root of that minus of m 0 and then we take the integral of v dv divided by root over of 1 minus v square by c square. So, if you do this integral and then put in the proper limits you know just look at the second line. So, when you do the integral and put in the proper limits. So, you get the one that is given in the brackets there that is m 0 c square divided by into root over of 1 minus v square by c square and then the limits from 0 to v. And then the whole expression simplifies. So, whole expression for the kinetic energy simplifies into two parts. See that it simplifies into an expression for the mass of a body which is moving with a certain velocity v times c square. Why the mass of the body being m 0 divided by root over of 1 minus v square by c square that is the total mass of a body when it is moving at certain velocity v that is multiplied by c square minus then m 0 m 0 is what m 0 is just a rest mass of the body times c square c being the velocity of the body. So, that is what we have that is the total kinetic energy of the body. Now, kinetic energy of the body being that we can interpret the total energy of the body as something like m 0 divided by root over 1 minus v square by c square times the c square. So, that will be then equal to m 0 c square. We call it as the rest mass energy if we consider m c square as the total energy plus the kinetic energy. If that sounds a bit confusing it might a little bit. Let us just have a look at the next slide and that will clarify our concept. What is it? So, at rest when the body is at rest we know the kinetic energy is 0, but what happens to the total energy? Remember if you go back to our whole slide, if you go back to our whole slide we see that when the body is at rest the total kinetic energy is 0, but the total energy is still m 0 c square when the body is at rest. So, that justifies the word that justifies the term rest mass energy that is the intrinsic energy associated with the body even when it is at rest. So, when the body starts moving the total energy would be this intrinsic rest mass energy plus whatever kinetic energy the body has gained. So, that will be then the total energy. So, that is exactly what we meant by saying that we interpret the total energy as m c square and m being m 0 divided by 1 minus v square by c square. So, having known this concept of what a rest mass energy is let us just write that as e 0 just to signify that it is you know the rest frame of the body or the energy of the body when the body is at rest. So, as you said what is the total energy of the body when the object is moving it will be e and that will be equal to e 0 times plus the kinetic energy that is and what is that that is nothing but m 0 root over 1 minus v square by c square times c square and what is that that is simply m c square where m is the relativistic mass. So, you see how this e equal to m c square has come about. Now, of course, this is a profound result I mean it has not only altered physics it has altered the world actually. So, it is the first time you are seeing that you know the intrinsic mass is being related with the energy of the body and it has immense consequences in fields of in other branches of physics. For example, if we consider the energy production in the sun is there energies being produced by fusing hydrogen into helium. So, when you so if you add up the masses of hydrogen and you add up the masses of helium you would find that in the final product the total mass is not the same I mean the whatever you started total amount of hydrogen you know the total mass of the hydrogen you started and the total mass of helium that is produced you will see that it is less. So, where has this mass gone into and this mass has been converted into energy. So, hydrogen is being fused into helium and then some amount of energy is released. And that is the and that is the source of that well that is more or less the you know the source of energy production in the sun and to just to give you an example you know just to feel of the numbers or the amount of energy that is being converted from matter per second. About 4.4 into 10 to the power 9 kilograms of matter is being converted to energy per second in the sun. So, how you are going to find the total energy released per second that is the total power actually. So, you are going to multiply this number 4.4 into 10 to the power 9 kg per second into 3 into 10 to the power 8 meter per second square meter per second that is I am sorry meter per second and take the square of that and what do you find you would find that the total energy is nothing but 4 into 10 to the power 26 joule per second. Now, if you just consider the 1000 watt bulb, I remember nobody uses 1000 watt bulbs in the homes anymore you would rather use more efficient sources. But let us you know how how bright a 1000 watt bulb can be ok that is 10 to the power 3 ok that is 10 to the power 3 watts. If you divide 4 into 10 to the power 26 by 20 power 3 it is not it is nothing but 4 into 10 to the power 23. So, per second there the sun is shining like 4 into 10 to the power 23 1000 watt bulbs just have a feel and I just have a feeling of how large this power is. Well actually this is also an important lesson for us to utilize the solar energy in our daily lives. I mean it will you know if you work more on research in solar energy and try to harness this energy which is just coming to us free from the sun lots of this energy problem will be solved. Ok. So, I think you know appreciate how this E equal to MC square comes about and what the consequences of it are ok. Of course, I did not so far talk about nuclear fusion of you know in a very direct way I did not talk of nuclear fusion. But then I give you an example of fusion of hydrogen to helium in stars ok. But some other applications in nuclear physics let us see if you can do such things a little bit later. Ok. So, having talked of energy and mass let us see what the expression for the kinetic energy I mean whatever things that we have discussed so far whether it actually boils down to our known relativistic non relativistic formulae if we take velocities less much much less than the velocity of light. So, let us check if the mass times the energy you know mass times the speed of light squared from where from you know we have derived the kinetic energy let us see whether we can get the proper limit here. Ok. So, we know the expression for the kinetic energy that is the total energy minus the rest mass energy of a body ok. Now since we know that the velocity that we are considering here is much much less than the velocity of light. So, we can we do an approximation here we do a binomial expansion of 1 minus v square by c square to the power minus half here ok that is the denominator of m 0 c square divided by root over 1 minus v square by c square what is that? Well the first term is 1 plus you know the term of importance half times v square by c square. So, you plug this in the expression for the kinetic energy ok it becomes 1 plus half v square by c square times m 0 c square of course and then you subtract m 0 c square from here ok what do you get? It is very simple you get half m 0 v square ok. So, indeed since the mass of the body does not change in non relativistic classical physics it is half m v square and then m being the rest mass of the body ok. So, we do see that it reduces to the classical limit at low speeds. So, having talked of mass energy and then seen and then having seen that it actually does give us the proper limit of the kinetic energy at low speeds. Let us now move a bit and bring in the momentum ok remember we started this module by talking of mass energy and momentum. Let us talk of energy and momentum ok. So, how are they related? Well you know from your previous slides here that the total energy is m 0 divided by 1 minus v square by c square times c square that is m c square. What is the momentum? Well that is m times v m being your familiar m 0 divided by 1 minus v square by c square ok. Well, but looking at these two expressions mathematically you see that you know the mass portion remains the same, but then you know the only thing different is the c square for the energy part and the velocity v for the momentum part. So, what will happen if we you know try to put them together on the same footing? Ok. What happens? For example, if we just do e square minus p square c square. So, what we do is that we square the energy and then from that we subtract p square times c square ok. Now, you will check that of course, that will have the that will have the dimension of the energy square ok. But what is it? Well does it give us something very interesting? Actually it does. I mean if you do the algebra it is rather one or two line algebra. You will see that it is nothing, but when you do e square that is the total energy and from that you subtract p square that is the momentum square times the velocity of light square. You are going to get something very interesting. You are going to get m 0 c square whole of that square of that whole square of that that is. So, that is nothing, but the rest mass squared of the body. So, if the body has a total energy e and it is also having total momentum p I mean it is moving with a certain momentum p then e square minus p square c square is nothing, but the rest mass square of the body. It is an interesting concept actually it is a because what it tells you is that this group of variables e square minus p square c square remains invariant in all reference frames. Of course, these reference frames are moving with constant velocity with respect to each other. So, that is what we have we have e square minus p square c square to remain invariant. Now, well that was that was that was that has the dimension of energy square. Actually it need not be I mean we were also having momentum. So, we could also in a sense have this as the dimension of momentum square. Well, that is very simple all you do is that you divide the entire stuff by c square and then you have e square by c square minus p square. And then the invariant quantity will come out to be m 0 squared c square. Now, remember m 0 is the rest mass of the body and c of course is the velocity of light. And this has the dimension of m 0 c that is has the dimension of momentum and then m 0 square c square has the dimension of momentum square. So, we will spend some time on this relation and then find out certain interesting things. But before that let us continue a bit on these units. Remember in relativity and in like other domains of physics we are quite interested in units in which you measure everything in terms of something in terms of the units of energy. In atomic physics for example, the unit of energy is generally electron gold Euclid physics MeV million electron. So, what is that what is E V? So, E V is nothing but the energy gained by an electron accelerated through a potential difference of 1 volt. So, if you take a million times of this that is 10 to the power 6 E V that gives you MeV and then when you take 10 to the power 9 that is 1 billion E V you get 1 G E V that is a giga electron volt that being the unit of energy. What about the mass? Well normally you would measure everything in grams or kilograms kilograms it is SI unit. So, however if you consider the expression E is equal to m c square you can very well measure mass in terms of energy by c square then you can measure mass everything in terms of in example like MeV by c square or E V by c square G E V by c square. So, that actually helps a lot. So, what about the what about the unit for the momentum mass times the velocity. If you measure velocity in terms of the how much of it is a percentage of velocity of light so if it is MeV by c square then you multiply by c it should be MeV by c or something like energy by c. Well that is very normal because if you just consider E square is equal to p square c square plus m 0 square c to the power 4 then the momentum does turn out to be energy by c. And then you can measure it in terms of MeV by c or let us say the G E V by c if it is an ultra relativistic momentum that you are considering. Now, let us consider something else one other application it is whether one can have massless particles. And I see this as an application of relativity is going to realize that in classical mechanics we kind of never ask such a question. Why? Because well once you have a massless particle or you do not have you have matter which is massless well in classical mechanics such a thing does not exist at all because you see if you have a something massless I mean what is massless in classical mechanics nothing I mean you consider unless you know you have an object which is a material matter then you say it is massless of course then object is not there. So, but in any case if you want to take this argument a little bit further if m is 0 the momentum is 0 the energy is 0. So, such a question does not happen does not arise at all. So, massless particle cannot exist in classical physics or in a non relativistic situation. However, in relativistic situation do we have a massless particle to exist does it you know well it is more like in classical physics it forbids the existence of massless particle, but thus relativity forbids such an existence. Let us let us just check it out well if indeed the rest mass is 0 you would find the total mass to be 0 if velocity is less than c why because m 0 is 0 and the denominator is 1 minus v square by c square is finite and then that is so the total mass m is 0 and then immediately you are going to figure out that the momentum is 0 and the energy of course is 0 fine. So, if the rest mass of a body is indeed 0 and it is moving with a velocity less than the velocity of light then massless particle should not exist. But what happens if we still have the rest mass to be 0, but the particle is moving with the velocity of light itself it is strange is it it. So, then what you see is that the expression for the momentum and the energy becomes 0 by 0 it is an indeterminate form it is an indeterminate you cannot determine it is 0 by 0 form. So, it is basically you cannot say that it is 0 neither can you say it is actually infinite it is actually indeterminate it can have any value. So, in a sense relativity does not forbid the existence of massless particle if and in this case and only if it moves with the velocity of light. So, that is a very important conclusion that you can draw it is that massless particle will be existing only and they will have energy and momentum provided the travel with the speed of light. Actually can you can you can you name such a thing exactly you can it is called the photo. It is the quanta of light then how are the energy and momentum related in this case? Well, since the rest mass is 0 then energy is equal to p times the velocity of light here it is e times p because otherwise e square is equal to p square c square plus m naught square c per 4. So, the m naught square being 0. So, you have e square is equal to p square c square and here. So, e is equal to p into c that is one. So, that is an important conclusion that we have special relativity. So, now let us change tack a little bit and return back to our energy momentum relation and see something quite interesting. So, what do we have here? We have basically e square by c square minus the momentum square. Remember this what we write as the small p that is the 3 momentum that is equal to m 0 square c square and then I write that as capital p square just to give you an idea that the invariant quantity that you have has a dimension of momentum. What kind of momentum is that? It is definitely not the 3 vector momentum that we do in our daily lives. So, that is what I said. So, the capital p here has the dimension of momentum and then p square of course, has the dimension of momentum squared here which is different from small p. Now, what is small p? Now, small p is let us say it is the momentum well it is the 3 momentum of a particle. Now, if you take the 3 momentum squared, so the norm of the momentum I put a vector sign on top of small p. What does it mean?  Then what does it turn out to be?  If I write for example, p x square plus p y square plus p z square in Cartesian coordinates and that is invariant, you know that because that is equal to the length of a vector that is invariant. Even if you rotate the vector, the length remains the same. So, the vector, the 3 vector is the one in which we put the vector sign and then we have 3 components. So, we have 3 independent components. Now, check that the momentum or the you know we can define a 4 momentum which capital P whose which has of course, 4 components and to keep in you know in in consonance with the 3 momentum that we had earlier p 1, p 2, p 3 which is denoted by vector p. We have the first part as p 0. We just call this as the 0th component of the 4 momentum and then if we define something like the 4 momentum dot product, I put the dot product in inverted commas and then you put a bigger dot p big dot p and all capital P's. Then we define that as p 0 square minus p dot p the vector p dot vector p, then we can get something quite interesting. Actually, we can relate what we have found here with the energy momentum in special relativity. So, if you identify p 0 as e by c and so the total p becomes the capital P becomes e by c and then the other vector is the 3 vector. Then the you know the 4 vector dot product becomes e square by c square minus small p square and we know that that is invariant. Now, just like the dot product of a vector was indeed invariant here too, the dot product or the big dot product of the 4 vector is also invariant. So, there is something which is happening here. I mean, so I think if you have not got it in these two slides, do not worry. I am going to talk a little bit more about the 4 vectors and space time a little bit later. So, I just want to tell you that there is something interesting that you can relate this energy momentum with things called the 4 vectors. Let us see what that is. Well, to change stack yet again and do a little bit of formal stuff in terms of Minkowski, we are doing relativity, Wanda's relativity in terms of Minkowski space time remember in special relativity. So, it is not only the space part, but we also have the time part which is which is equally important here. So, because here time is no longer an independent quantity, it also depends on the space quantities. That is what we saw in our Lordin's transformations. So, if you define a quantity, an event, let us say or the world point by 4 space time coordinates, since the velocity of light is C which is constant in all frames. So, what we have here is that we take X as CT and then XYZ. So, why have we taken CT? So, that we preserve the same dimension as the space coordinates or you could even have make it look like you just say you have 4 coordinates X0, X1, X2, X3 and then X0 is the 0th in a sense, 0th component of the thing called X capital X here and then small X1, X2, X3 these are the space coordinates. So, that is what we say X0 is equal to CT and then the vector X is X1, X2, X3 or XYZ if you wish in Cartesian coordinates. Now, what is the squared norm of this quantity? As we have defined, it is C squared T squared minus X1 squared minus X2 squared minus X3 squared.  So, what we have? So, what we have is that in S frame if we have a point which is denoted by you know one of this world space time events denoted by CT XYZ. So, certain event is occurring at a certain time in a certain position space. Now, the same event will be viewed by someone in the S frame which is moving with velocity V with respect to the S frame as CT prime and at time T prime that is and then at position X prime, Y prime, Z prime. Remember at T equal to and T equal to T prime is equal to 0, this two frames were coinciding and then it started with the move with velocity uniform velocity V that is. So, how are these things related? So, these quantities are actually related by Lorentz transformations. So, what is X prime? Well, X prime is nothing but I mean if you use the notations gamma and beta remember we had used we are using them so that the expressions become less cumbersome. So, beta beings V by C and then gamma becomes 1 minus beta square root over or to the power minus half basically 1 by root over 1 minus V square by C square. Since we are moving uniformly along S frame is moving uniformly along the common X axis and so what is X prime? So, X prime is nothing but in terms of the X quantities, it is gamma times X minus beta CT and Y prime of course is equal to Y and then Z prime is Z and then CT prime is gamma CT minus beta X. So, what happens to the quantity capital X prime? So, if you do C square T square minus X square minus Y square minus Z square you should check that this becomes equal to C square T prime square minus X prime square minus Y prime square minus Z prime square. So, the norm of the quantity X capital X that is of the 4 vector remains invariant whether you are doing it in the S frame or the S prime frame. So, that is what we have and in fact that gives us the idea that if we have, if we can figure out a set of 4 quantities of 4 numbers that transform as the components of the 4 vector X capital X that is they will be 4 vectors. So, and then not only that I mean just about any 4 quantities will not be any 4 numbers you just club them together they will not be 4 vectors. Well their components should transform like the components of the space-time coordinate capital X which is basically they should transform by the same Lorentz transformation. Not only that the norm of the 4 vector that one has constructed should be invariant under any frame. To give an example just think of any other 4 vector let us say a general 4 vector some vector A remember since I am using the word 4 vector not a 3 vector that is what I have not put a vector sign on top of A capital A that is. So, in the S frame that is it has components A0, AX, AY, AZ and in the S frame it has components A0 prime, AX prime, AY prime and AZ prime and that is the vector A prime that is the 4 vector A prime. Now, if A is a 4 vector in S frame and S prime is the 4 vector seen from rather A prime is the same 4 vector seen from the S prime frame then there are certain conditions that should be obeyed. Well first of all the components of A and the components of A prime should be related by the Lorentz transformation. And not only that the squared norm of A and A prime they should be equal and it is actually Lorentz invariant. So, that is exactly what we had for our energy and momentum if we define the 4 momentum as E by C and that is the 0th part and then the other 3 parts are the familiar 3 momentum vectors let us say the 3 linear momentum PXP by PZ. So, if capital P that is the 4 momentum vector in S frame which has components E by C and PXP by PZ and then the same thing seen from the prime frame is capital P prime and that is E prime by C PX prime PY prime and PZ prime small PX prime PY prime PZ prime that is the 3 momentum vector in the prime frame. Then the components of P and P prime are related by none other than the Lorentz transformations. Well this has some immense consequences actually because in a sense this will help us in relating the energy and momentum in one frame with the energy and momentum in another frame. And not only that you can also you can well you can also relate energy momentum conservation directly in the S frame and the S prime frame. So, more of that a little later but then to summarize what we have talked of 3 vector and the 4 vector let us just spend 2 more slides on it. For a 3 vector let us say the velocity vector the radial vector things like that 3 vector of course has 3 components. So, we put a vector sign on top of that and 4 vector of course will have 4 components. Now why is it that we call this 3 component thing as a vector by the way? Well it is because if you are changing your coordinate system and then you are following you know the change of coordinate system is due to is the change of coordinate system is due to this transformation you need this transformation matrix R to go from one coordinate system to another. And similarly in this case of 4 vector it is the Lorentz transformation which is transforming from S to S prime. Now a vector I mean we define a vector to be that to be that physical entity is that look at the 3 vector part. So, if you look at 3 vector part and then you see that x vector x is transformed to vector x prime. Now it is the same transformation matrix which will do the transformation. So, the transformation matrix which is transforming coordinate system O to O prime the same transformation matrix will be responsible it is the same transformation matrix which will transform x to x prime. So, that is a vector and not only that the length of this vector in the O system and the length of the vector in the O prime system will be preserved. Similarly, what you see is that it is a Lorentz transformation which is transforming the quantities in the S frame to the S prime frame. So, it is the same Lorentz transformation which is going to transform the components of the 4 vector in S frame the components of the 4 vector in the S prime frame just like the transformation matrix R transform the components of the vector x in O system to the trans components of the vector x prime in the O prime system. And just like the length of the 3 vector was constant here what you see that the square norm is Lorentz invariant. So, that gives you an idea why we had used this word vector for this 4 component entity in special relativity. Now, of course, there are lots of applications to using 4 vectors. We have just been introduced to two of the 4 vectors one of course is the space time 4 vector and another is the 4 momentum 4 vector. Now, these are going to have applications in relativistic kinematics and things like relativistic collisions. So, let us talk a bit about such a thing about our coordinate systems in a case where such collisions can happen namely the laboratory and the center of mass system. So, what is it? So, basically we are considering the collision of two particles A and B let us say there are certain there are rest masses M A and M B. And let us say that well you can look at this either in the laboratory system and the center of mass system. Well, in case we want to know what these systems are the lab system is one in which one of the particles is at rest and the other comes and hits it with a certain momentum you know certain momentum let us say 3 momentum P or vector P. In this case, let particle B be at rest and then particle A is moving with a certain momentum in the lab frame P AL notice the vector sign and then the subscript AL L stands for the laboratory quantity. So, wherever you see this L it means that it is the lab quantity. So, in a sense what is the momentum for vectors here? Well capital P AL that is the we will read 4 quantities the first quantity relates to the energy and well it is basically the dimension of momentum it is but involves the energy that is E AL by C and then the 3 vector with which or the momentum with which the particle A is moving. What about P BL that is the 4 momentum vector for particle B in the laboratory frame well that is E BL by C and then remember it is at rest. So, it is total moment that is a linear momentum is 0. Now, what is E AL? E AL you know that it is MA into C square and then what about E BL? E BL is nothing but MB into C square. Now remember here E AL now when I write MA here it is MA divided by 1 minus V square by C square actually that is assumed within when I write E AL here. But when I write E BL here remember that it is just the rest mass squared. So, we conclude our discussions here today once we have seen the differences between the 3 vector and the 4 vector now we realize why we call it as a 4 vector itself keeping it you know some sort of consonants with this component of a 3 vector. We are going to see in our next topic the applications of this of the 4 vector in in special relativity especially in relativistic collisions and we will also do some more problems in relativistic kinematics in our next discussion. Thank you very much.


There is a new scam that's happening on Facebook that some of my clients almost got tricked by. It looks like this in the notification fan page policy issue verification info mentioned, you know, your your fan page. And then if you click on it, it opens up to a post that looks something like this. Now I know right away that this isn't Facebook because well I've been around Facebook business stuff for a long time and I know that this is not, whoops, this is not the typical kind of notification. From Facebook, an notification might look something like this and or you know there are certain flags that we notice but something that looks kind of yeah this just doesn't doesn't look right to me and when I went to the post it does absolutely doesn't look right to me. Well, so don't click on it. Don't click on something like this but I want to show you what happens if we do click on it. So I'm going to go ahead and go into an incognito window and go to go to that link and see what it looks like. I bet it's going to try to yeah okay that's what I thought. This is an example of a phishing site. What's a phishing scam? It makes it well they do a poor job but they they try to make it look like it's from Facebook but if you or meta and people who are you know unaware of this kind of thing will go okay well let me go ahead and put in my Facebook or my email address and Facebook password and click confirmation which is also kind of for the safety of users I mean I mean you can kind of tell various little signs like capital P after a comma it's like clearly not uh native I don't think native English speakers plus it says not secure at the top plus even though it's just Facebook in the beginning you always have to look at the end of url that the dot com or dot net or dot whatever right before that this is not facebook.com or dot net this is ddns I've never heard of that website before and they just make it look like a facebook thing so if I were to put in my email or phone and Facebook password in there now they have access to my account now they can hack my facebook etc so this is a very common type of scam uh it's called phishing phi shing so I hope you don't get taken by this and I hope this is helpful


Well, I will wait for the answer game. Let's harvest some grapes. Let's harvest some The odds are we're probably gonna fill all of this all good now, okay Let's see the answer. Oh, no, it's not What is your favorite beverage? What's my favorite beverage water is my favorite beverage? But tea I like tea. I like tea a lot. I've been dying to take this one down Like this one is Beautiful, it's just been hanging here for like just growing and get juicier harvest. Let's do this Green tea is awesome Oh, I gotta put on my glasses to be able to read that What happens is next year? I'm gonna make sure the grape but the grapes the fruit is not growing into each other I freed up some of them where they're hanging but I have a whole bunch there. That's just growing together Look at these so juicy So good. I'm gonna make a little bit of great liqueur with this stuff. It's all just growing together right Turn into raisins even that's one bowl. We're gonna do more Let's fill up another one. Awesome Awesome, sir, if I'm not checking the chat game are missing grapes so nice Let's do more a bunch over here. Just beautiful Just beautiful. Oh, but I can't even reach us over hanging the balcony some nice big fat juicy one Chicha will take one bowl 30 bucks Shipping would be like 200 Awesome Let's go for easier pickings for now. Here's one that's turning into a raisin. Here's three bowls We're gonna do one more bowl. Okay. One more bowl is gonna be easy pickings as well. So what we'll do We'll do one more bowl. It's gonna be easy pickings and then I could do more bowls, but the other bowls are gonna be Reaching higher and around overhanging the balcony and we have a Fair bit of grapes coming up the steps So I'll have to go around the other side and see what I can harvest on the other side But let's do one more bowl. There'll be four bowls. We're gonna make our liqueur and or have enough to make our liqueur which most likely will do a live stream of as well making most likely some Grape sauce Lake Last time I cooked it up. So I made grape paste That we ate with bread and sour cream and stuff so good And we got the juice out of it where we could make concentrate and then just make grape juice with soda and stuff like this So super good as well No, no, I won't risk danger For maybe for grapes we will but not too much danger These ones Nice two more bowls, so we got four bowls of these Okay, that's good for now. I'm gonna go wash my hands just rinse them because they're sticky right now. I came out This is via just woke up Say hi, I'm gonna take the grapes inside actually guys. So via doesn't get into the grapes I'll be right back. That's a fun thing to do for Saturday morning Harvesting grapes the bees are going what you got here, man or the wasps not bees Just give them a little rinse Look, they're seriously These are some of the best grapes I've ever had. I don't know why but they are They have the perfect amount of tanginess and sweetness and juiciness So good Fantastic Wow


morning on Monday begins. This is Stink Tech, I'm Jay Fidel. This is Brett Obergaard next to me. He's a professor at the program, the journalism program at the communications department U.H. Minoa. And he comes from time to time, not often enough, but he comes from time to time. Let me talk about media issues. And he was a player, a panelist in our morning media symposium, which was October 10th. And he answered a question that day, participated in one of the two panels. And we covered changes in the media, challenges to the media. We covered solutions to these problems, and we covered survival of the media economically and in our democracy, such as it is. Welcome to the show, Brett. Well, thank you for having me again. Well, let's talk about the trip you just made first. I went to Google. I mean, that's exciting. I would always like to go to Google. What did you go for? What did you learn? I went to a machine learning workshop at Google's San Francisco headquarters, not their Mountain View headquarters, so right downtown in San Francisco. Very nearby to where they just had a machine solve the Rubik's Cube for the first time. I don't know if you saw that in the news this week. It was almost like one building away from that. And it's kind of like the hub of AI in San Francisco and the world, essentially. So we were there to learn about how to make media more accessible to technologies. And it also brought to mind a lot of ideas about how news and journalism is going to change based on AI as well. Yeah. I mean, it's an irresistible possibility that technology is moving so fast, especially technology around info technology and social media technology, that it will affect, it is affecting the media and journalism especially, and that in turn affects our democracy. So this is really mainstream stuff, actually. And I just wonder... Well, accessibility, too, because... Accessibility, of course. If a piece of media is not accessible, then it might as well not exist. You imagine if you go to another country and you be assigned in a different language and you can't read it, it basically offers you no help. And there are a lot of people, for a lot of different reasons, can't access media in the country. They're blind, visually impaired, hard of hearing, whatever the situation, dyslexic. And you start parsing those groups off and suddenly you're into the millions and millions of people who are disenfranchised from public discourse. Yeah. And participation in whatever government they have. And in the community conversation, which is always valuable, I mean, I think we need to have community conversations. We also need to have smaller conversations. Right. You know, what comes to mind is I saw an article recently about machines that you can buy that you and I can buy, which translate language from one to any number of 80, 90 languages in the world. And it comes in, you know, it's like on your cell phone. And that's changing things. So you can travel, travel is so much more important. Or you can communicate on telecommunications. But there's really no barrier about language if you have that. There's also no barrier between somebody who can't see but can hear, somebody who can hear, but not see. Did I get that backward? Somebody can not hear but see. And all these translations. Yeah. At the workshop I was at, I was sitting next to a person who was deaf from birth. And he was watching a live transcription. So Google has a program called Live Transcribe, which is free. You can download it. And it not only translates a speaker, but it'll translate into 70 languages instantaneously. So as a person's talking, you can put your phone up and it'll transcribe it right on your phone with the person saying it into different languages. That's a high degree of accuracy, I'm sure. Pretty high degree of accuracy and very, very fast. It's just, as soon as a person says something, you know, because a lot of times, particularly people who are deaf or hard of hearing, they're in a situation where they're, say, reading lips or whatever. It's very hard to have a socially not awkward conversation because there's pausing and things that we're not used to in ordinary conversation. And this allows that to be minimized. It's not completely eliminated, but minimized. Well, that's really at the cutting edge for journalism.  This is a matter of distribution, isn't it? Well, translation, yeah. They also have a new app that's not quite out yet, but we've got a test stick called Google Recorder, which allows you to record and transcribe at the same time, say your interviews. So you'd be able to download this free app, do an interview, your transcript, it'd be immediately available and you could immediately email it to somebody or whatever to your editor. Is this available now? Not quite yet. It'll be the next couple of months. It's available on the Google Nexus phone, but not available on all androids yet. Oh, wow. That will change things. It's one of those programs that we've been looking for in journalism. It'll help tremendously in terms of efficiency. Because normally when you do an interview, you have to go back and transcribe it yourself or you pay somebody to transcribe it just to make sure you get the quotes right and everything. And this will do it for automatically. And it's also time-coded with the audio. If you're like, oh, what was that quote on such and such? You type in a search term, it'll go right to the audio and it'll allow you to grab that clip out. It'll change things. Yeah. It'll be a really, it'll be a really good, it'll be a really important tool. Tools like that. I'm not just saying Google's tool, but tools like that are going to change the way we report. It just came back, no? Yeah. Got to do that. You know, got to stay up at the cutting edge. So let's talk about the program, Morning Media Symposium. It's about media. There were a lot of people from the media there who were very interested in the media. And you spoke, what did you speak about? You had a specific topic, a question that you had to deal with. What was it? The primarily was how would you allocate resources if you had 20 newsroom staffers, no worries about advertising, no worries about, you know, furniture in the newsroom in terms of like the things that you have to do. Just like what would you do with 20 people and no budget concerns? And what I really wanted us to focus on in journalism, and that's what I try to do with my students, is you focus on a couple of things. Your story is identify new problems and then offer solutions to new problems. I think one of the most frustrating things for me as a reader or listener or a watcher of journalism is people give me problems that I already know about and then they don't tell me how to solve them. It's just like a kind of constant irritant. So if it's a problem I already know about or, you know, anybody would know about. It's been going on for decades or whatever. There's no point in just kind of needling somebody, hey, it's still a problem. What I think journalists really need to do is find the solutions and present them to people. And then if there's some power structure that's not pursuing those solutions, then hold those people accountable. Well, you know, one could argue, not me, but one could argue that that's opinion. When you identify options that would solve the problem, isn't that opinion, and therefore not to be included with a fact-based journalistic story? Well, the journalism umbrella is very large. It includes, of course, opinions, editorials, where the festivals are, they're called service journalism. Journalism is a very wide umbrella. I would say providing potential solutions is a core of what journalism does as a fact-based enterprise. It's not outside of that in any way. And it's also, I wouldn't consider it opinion. It's simply a matter of, you know, here's the problem. Here are some ways we've identified to fix it, which one of these are we're going to try. Because journalism is really about the conversation with the community. It's not about, you know, necessarily chronicling all of humanity. I mean, there's millions of things that are not in a journalistic discourse every day. There are billions, trillions, I don't know, an infinite number of things that aren't included in there. So it's already filtering it down. And what we have left is, you know, in my mind, if you have the local robbery and it takes up, you know, 90 seconds of your newscast, and it's only 30-minute newscast, then, you know, what's left out? You only have that much resource to put in there. And what's going to be solved by showing that that robbery happened, you know, the robber's been caught. It's an isolated incident, robberies happen all the time. You know, I'm going to say it's not a value, but let's talk about robberies across the city. How can we stop that or something bigger? And I think too much of our journalism is just filling the holes. And that's, to me, why we've lost the market to social media because journalism became more entertainment than information. And then as it became more entertainment, it became more dispensable. Yeah, I'm with you all the way on that. So, I mean, for example, homelessness or climate change, those are major problems in our world that both affect us like it or not. And I think a lot of stories that you see are the poor homeless, but they don't give you the options. They don't weigh and balance the options. They don't give you a path on which option, what collection of options would be appropriate to solve or deal with the problem. And that's the real story, or what agency or person or, you know, altruist is working on what option. That's the real story. The same thing with climate change. I had a panel one time, another program, another group and said to my panel, I'd like to hear action points. Yeah, I don't want to hear that there's a problem with climate change. We know that. Okay, and they went through all of them and each one in turn said, there's a big problem with climate change and nobody could bring himself or herself, you know, to actually deal with action points. And I mean, I'm refreshed to hear you say that's part of journalism to talk about the action points, whether this is a question I put to you, whether the action point has been in discussion in that community discussion before, or whether you the journalists have just thought of it.  We have decided where what priority are we going to put on these and there's not going to be a silver bullet that's going to solve it all. One example I thought was very inspiring was in India, they took a day off of school and gave it each child in all of India a tree to plant and they planted I think like 13 million or 30 million trees in one day. And when we're talking about the changes to the atmosphere and how we could solve it, I think the number is set at like say 300 million trees have to be planted to get us back to where we were. I'm thinking, well, it is 13 million in one day. So I think we could 30 million or whatever the number was. I'm saying like this is a tangible practical solution. Plant trees, pick up garbage, you know, if there's some debris in the ocean, let's clean it out. These are these are also economic ideas. Like here's a job. The job is clean the oceans. The job is pick up junk on the beaches. A job. I mean, there's all these jobs out there that we could do and also make our environment better and fix climate change at the same time. And these are things that are not in the typical discussion in a lot of media circles. And that to me is as part of our weakness. It's not a mystery to me why we've lost that kind of cornerstone part in the democratic discourse is because we've lost our way and what we're doing in many respects. We forgot that we are the bully. We the media is the bully pulpit. We have leverage. And so the media has found that out. We set the agenda. That's part of what journalism does. It's agenda setting on action points. Two things come to mind that I read about recently. I'm interested in your reaction. Number one, David Lionheart, New York Times has a newsletter. He writes a lot. The New York Times said, you know, this is a time when the public should speak up on the question of impeachment. This is what the politicians are waiting for. They're waiting to see what the public reaction is. So if you want impeachment, now is the time to get out in the street. So that's an interesting kind of suggestion. I mean, his opinion is obviously not, you know, fact based journalism, but but but he was using the bully pulpit. He was saying he is saying, you know, if you if you want to make a difference, this is all kind of reverberation. If you want to make a difference, get out in the street with a sign and say you want impeachment, if that's what you want. I found that interesting. The other one, and this is more funny than anything else, is Bill Maher, one of my favorite publishing comedian commentators, has this thing going on about we should all send money to Trump and buy the presidency back. If 1000 multimillionaire billionaire people gave him $1 million each, that would be a billion dollars. Maybe he would take the money and just leave the presidency. I heard that one before. That's a pretty good idea. Save a lot of anguish. You know, it shows you and it's sort of on the continuum to my next question. It shows you that the press does have leverage because it is the pulpit. Because theoretically anyway, it reaches a lot of people or it has reached. They think that's changing now. And as you say, the press has lost its mojo in some way. And maybe it's not as much a bully pulpit as it used to be. But if I made outrageous, outrageous, but aggressive, strident statements, if I made calls to action, do you think that would improve circulation? I don't know if it improved circulation, but what I would think if we could put the important issues on the table every day and have people address them, as opposed to the whole filling mantra that I think we have. And that's across the media. It's in television, newspapers, websites, whatever. They fill the holes. And with protesting, I think these are, this is where say coverage of a protest could change minds. Like if we had every time there's a protest, you had extensive coverage of it in all the media, that would maybe make a difference as opposed to there's a there's a big rally and you don't even see a photograph when the star advertiser about it. So that's I think part of part of the disconnect that we have. And social media is changing that like with Monacaia, you have I think that that group's been very effective with social media to keep that issue at the forefront. And then the news media has sort of followed the social media instead of the other way around. And the protesters are looking for the cameras. Protesters are talking to the camera, they're looking at the cameras. And this is what I think all of us can do as part of building our democracy is try to get our message into the, you know, bigger discussion. It reminds me of that quote I found from from the comedian who has played for a long time and got off. It's a New York apartment. Yeah, I forget his name right now. And he came up with the notion that it's amazing. Is it not that the news in the news that the newspaper covers that, which is just there's just enough room in the newspaper to cover the news for that day. Yeah, just amazing, amazing fit. And what you know, with that, of course, the joke is that there's really much more news that they're not putting in the newspaper. And if there's less news, they have to expand it, then they're just filling, filling holes, did you say? Yeah, but the problem is, as the newsrooms have shrunk, there's less resources devoted to making news. And then that's where the filling comes in. And this is kind of a death circle, a death spiral, where you keep cutting journalists and you keep making them do more and more stories in a day, and you're going to get worse and worse stories. And then people are going to find those less and less valuable. So then they're going to turn to your channel less and less.  Yeah. Jerry. Fine film. That was the guy. Yeah. Well, okay, let's let's go to the next part of this discussion, which is the article I found in the New York Times a day or two ago. And it reminded me of my own question that I put during the second panel, which I don't think I put it very well. But my question was something like, you know, the media has a problem in terms of business models, raising money, pay for the cost of all that reporting, pay those 20, 20 team members that you were talking about. And then you have the down spiral. At the same time, social media is making tons of money, and the news is not necessarily accurate. It comes from all sources. Some of them are bad sources. And this is the most troubling part of all is that I can, I can disseminate news to a huge number of people through Facebook, or some of the others, by paying them for ads. And they will deal with me. They actually had people embedded in the Trump campaign in 2016, advising him how to do this. And I'm sure they're doing exactly the same thing. Hillary Clinton wasn't doing that. She didn't have that advantage. And Brad Parsquale, the guy who was the social media manager for Trump in 2016, is now Trump's overall campaign manager. And Trump is spending like $50 million recently on all the social media on its messaging and its news that isn't necessarily true. And somebody is paying him to put it there. It's, ad is the wrong word. It's much broader than ad. It's what they do. And of course, this has a lot to do with Analytica, Cambridge Analytica, and how they made a living and how they affected elections, not only in the US, they affected the election in Brexit and in other countries around the world, a collection of them, and they were getting really good at it by the time of the American election in 2016. So bottom line is there's a living to be made. There's money to be made in fooling with social media. And social media is making oodles of money. And, you know, Google is one of them. Facebook is, of course, Twitter. And so what I see is sort of a, it's a competition. And social media is winning the competition, but the public is losing it. What are your thoughts about it? Well, more than half of American adults get news from social media. So the channel is very robust. There's nothing really that can compare to Facebook right now in terms of news dissemination. Yet, Zuckerberg and Facebook take no responsibility for what they publish, which to me is just ridiculous on its face. It's aberrant. It's, you know, this is something where the government has to step in and solve this problem after regulating. Isn't it trouble you to say that the government has to step in? No, it doesn't trouble me because this is a speech is regulated in lots of ways. We have free speech, but we don't have free speech to threaten people with bodily harm. We don't have free speech. You'll fire in a movie theater. There are things you just, it's free to an extent or doesn't impact other people. In this case, spreading propaganda, which is what I would call what most of what appears on on Facebook, and that's not just for Trump, it's lots of people do it, is something that needs some regulation, just like it's been regulated in all the other publishing houses. So everybody else that publishes information is regulated to have, you know, either factual information or, you know, discourse of benefits of public in general or whatever. There's some kind of public good that it entails. For example, if you broadcast over the airwaves, you have an FCC license that requires you to serve the public, not just, you know, tell things. And this is something that social media doesn't have, and to me it's something I think the government needs to come in and clean up. This is, I'm not talking about infringing on free speech. What I'm talking about is regulating the type of speech that this particular channel can use. And that is, that's to me like a fundamental step we have to take and basically just call Facebook and Twitter publishers. That's what I would do. And then have them follow the guidelines we already have in place for every other publisher in the world. So somebody has to set the standards though.    I fully support that. But what I'd say is when you're creating a system that elevates massive amounts of propaganda, that needs regulation. It's not, not free speech in the sense that people, ordinary people, want to have their say. It's propaganda, but through fire hose. And that to me is very, very dangerous. There are some people listen to it. That's, that's a problem of education. Millions of people listen to it. Yeah. So the question, the question I put to you was just, can we take a moment and drill down on that? Alright. Can we talk, as you suggested earlier, about options? Okay. So, okay, I go to Congress. So let's assume Congress is healthy at the moment we go to Congress because it is dysfunctional now and you can't get anything through it. So what, what's the bill? What does it say? You can't do propaganda. Social media platforms operate under publisher laws. You have to be a publisher. They're a publisher. But you're not going to require them to register or anything. Just, just do some things. They have to, within a definition of publisher. Right. And this is, this would be like, you know, I could make a newsletter at FedEx and print it up and say whatever I want. That's free speech. But as soon as what I put on that newsletter is inciting like violence or whatever or doing something against basic humanity, that's when I'm responsible for it. I think not only you turn the social media folks into publishers, everybody who publishes on social media needs to be responsible for what they publish. And that's the only way to root out this system. I heard Zuckerberg's speech the other day about his claim to, you know, want to protect the First Amendment, blah, blah, blah. He really wants to protect his business. He wants to, because his business is going to fail otherwise. He's a, he's a publisher. Uber's a taxi service. Airbnb is a hotel. All these things they just, they want to, they're using loopholes in the law to, um, him off as much money as they can before people figure out the game. It's really aggravating to hear him talk about the First Amendment.  Yeah. I mean, to say that he wants a free speech and all that when he really is about taking our free speech and, and turning it into capital and then selling it. Okay. I mean, there are problems with this legislation because you have definitional things. What is propaganda?  I wouldn't go into that. I would say a publisher, you only have to publish one thing to be a publisher. Like, I publish one piece of paper. I'm a publisher. That's the standard. That's the standard we've used throughout history before social media. It wasn't a matter of a newspaper published 100 copies a day or a million copies a day. They are still publishers. There's a huge amount of law on this. There's a huge amount of law and legal precedent, libel laws, et cetera, that are all have been established over decades of court cases that really clearly share communal values. And right now they're superseding that. So what would you outlook? Propaganda, hard to define. Bigotry, hard to define hate speech. Bigotry, hard to define. And inciting to violence. That actually is easier. Well, I wouldn't, I wouldn't want to outlaw any speech in particular. But what I'd say is whatever laws we have in place for publishers, that's what each individual should be responsible for. And then the platform in a larger level should be responsible for. Including defamation. Yeah, libel's defamation. That's elegant. Well, it's easy. It's simple. It would, it would make so much sense. I was recently in an Uber talking to the driver about the situation with Uber. Uber essentially makes changes of rules every day on this driver.  They change the way they were. In California, the state legislature came in and said, you know what, Uber? You're doing this wrong. We're going to change the rules and we're going to set them.  You're going to operate like the taxis do. Because the taxis were set up not because they wanted to punish taxi companies, it's because they had certain things that we wanted to make sure happen. You wanted to have a safe ride. You want to have a regulated ride, like with costs. You wanted to make sure your driver was insured and all that. It's all these basic things that we agreed would be good for that kind of service. Uber came in and went through a loophole and made a lot of money. Well, good for them, but the gig is up. So has California actually changed that? Yeah. Oh, that's good. It's the same kind of elegant solution. Yeah. As far as I know, I'm getting this from the Uber driver, but essentially they're going to restrict the way Uber operates in the city of San Francisco. This is a statewide thing as well. So last point, Brett, and this is really an important one. And as a journalism professor, somebody who thinks about this at really all levels all the time for a career, I'm sure this would be central for you, is that how important is this whole discussion? How important is the media? How important is the competition between the conventional media and social media? And all this, you know, the problems that we discussed at the symposium about changes in the media, challenges to the media, solutions to these problems, and survival of the media. How important is it to democracy? I mean, if you looked at the Constitution, you'd get the idea that they thought it was really important. Well, not until the first amendment. You know, it was not in the basic Constitution. It was the first amendment. Well, first part, but how important is it as things work right now? The continuation, which is not guaranteed. You know, Ben Franklin said, it's a Republic, madam, but only if you can keep it. And query, can we keep it? And how important is the first amendment and the media to keeping it? Well, I think there are a lot of conflated issues in this where people inherently are arguing for business models as opposed to journalism. I hear this all the time when I go to journalism type events where newspapers are dying. This is so terrible. Our TV stations, all their viewers are older or whatever it is. And what they're really arguing is for the continuation of their business as opposed to protecting journalism and the future of journalism. What I would say is, you know, that we should get away from that kind of protectionism and move toward a refocus on what journalism does. And that's what you were talking about is it boosts and strengthens democracy. It's not about making money. It's not about, you know, having all the power or whatever these situations are set up like. Now, of course, this is very painful. They've had roughly 30,000 newspaper jobs lost in the last 10 years. And they've had roughly 13,000 digital media jobs that have come back in that place. Less jobs. But what people don't talk about is, well, what jobs were lost. You know, these, to me, this is where the evolution and refinement of journalism is happening. And it's not inherently a bad thing that we're losing those jobs. It's it's inherently a bad thing if the new jobs that replace it are worse at journalism. And that may be happening too. I'm not saying it's not because I find a lot of web content is very poor as well. Now, you look at somewhere like Civil Beat where they do a really good job at what they're doing and they're kind of bringing back new journalism jobs that are as good or better than what the old newspaper jobs were. Without a printed copy. Without a printed copy. And most people want their news on their mobile devices. They don't want, you know, I personally get a printed newspaper every day and I enjoy reading it over breakfast. But I understand that most people don't do that and won't want to do that in the future. So I accept it. You know, that's just my personal preference. And me to try to hold on to that because I like it, you know, that's not really fair to what the journalism is. Are you ready to give it up? Well, I'm just I'm just ready for what will bring about a better democracy. And the better democracy is clearly going to come through digital tools and and more direct access for all sorts of people. And that's, you know, that's where this change is going. So a lot of historians in journalism look back at the changes in the business models and they don't really fret about what's happening now because they've seen it before in lots of different circumstances. And if you think of, say, the rise of, you know, the yellow journalism era or, you know, the post-watergate era or whatever, there's always these surges and kind of cutting off the chaff and getting rid of the bad stuff and getting back to the good stuff. And I think that's what we're doing here. And, you know, eventually people will, I think, find that valuable. But, of course, it doesn't really help the person lay it off from a job.  And professionalism seems to me it comes from, it definitely could come, should come, probably is coming from schools like the journalism program at the communications department at UH Manoa. But how important are those schools to the future of journalism and therefore our democracy? And how, and what would you, what would you, how, you know, it doesn't pay very well these days. You can't stand up there at the head of the class and say, you guys are going to do really well here. You can't say that. They're not going to do that. I can, because I do. But you do say that. I do say that. I don't, I think it's a false argument. Okay. I studied journalism in college and was employed as a journalist for most of my life. And I never had a problem paying the bills. I did have friends who had public assistance at some of the small newspapers they worked at when they started, but eventually they moved into jobs that were family wage, middle-class jobs. You're not going to be rich in journalism unless you're Wolf Blitzer or somebody like that. Of course, those people make lots of money. So I find it somewhat false on its, on its basis to say that this isn't a good occupational job compared to, look at all the other liberal art degrees. Okay, you're going to be a sociology major. You're going to go out and make millions of dollars. You're going to have a job for sure. You're going to be a psychology major. You're, I mean, which one of the English major? Where are you going to be on this list? That you're, what degree are you going to get a big job? And then really importantly, in the STEM fields, this has been something that's argued so much. I just read a really interesting evaluation of the STEM fields in terms of how those degrees translate into careers. And what they found was that STEM degrees are really good at the first part of your career. And then your skills get outdated within, say, 10 years or so. And most, a lot of those people plateau. As opposed to a journalism major, an English major, sociology major, a psychology major, whatever, they learn these broader skills that allow them to become managers or, executives or whatever. And their careers actually, in the long term, can be more lucrative or more stable than the STEM fields. So this is somewhat based on a faulty premise. And also I think about like, what do you want to do for a job?  You want to get up every day and be curious about the world and go out and ask questions and find out about it and then tell people what you learned and what better job could you have than that? So that's my argument back on it. Yeah, no argument. You learn how to write well. You learn how to communicate well. You learn how to produce media. You learn how to be active in a democracy and know how it works. You know, you can learn it from the inside, going to council meetings, interviewing public officials. It's really a rich job. And yes, not everybody becomes a journalist at the end of it, but our graduates become government spokespeople, corporate spokespeople. They become lawyers. They become teachers. All sorts of things. And then that's where the argument for a journalism degree comes into play. And it gives you a consciousness about the country. It connects you with the news, the community, and the sea changes.  And arguably, it saves our democracy. Well, it's a true-seeking ideology. That's what I call it. So you seek truth. We teach you how to seek truth and find it. And then what you do with that truth is up to you. Thank you, Brett. Brett Overgaard. Thank you. Professor of journalism. Thank you so much for coming today. Yeah, thanks again for inviting me.