So, I think according to our plan today, we start discussion on the astronomy in media of India. And in media of India, I mean to say actually, Siddhanti astronomy was continuing, but main thing that because of outside innovation started coming again and again and the rulers were also coming from outside. It is not like previously the shocks coming, wounds coming, but they are getting absorbed here, but this time the rulers were coming from outside. So, lot of activities were interrupted and many well south of Bhinjar, but at the same time the new influence came and some new types of astronomical activity started and some of those things we will discuss. So, today what we will discuss is that interaction with the O-station G's astronomy which we call and then important contribution by Shwai Jai Singh and it will be interesting because though he did not do any fundamentally new work, but his observatories you all see and they stand still as more or less as tourist attraction I must say. So, when he played some role in astronomy, now the northern part of India, the astronomy continued to be pursued, but under the influence of waste station astronomers and sleep rulers and as a natural consequence to that G's astronomy took roots in Indian soil. What is G's astronomy? Now in West Asia one of the main task of the astronomers was to prepare astronomical tables called G's. Now G's is a table, astronomical table and they needed it very badly because they follow also strictly lunar calendar as you all know and this kind of astronomy which is primarily based upon G's that is table they are called commonly G's astronomy. So, there are three types of G's, one type of G's is G's is G's is a Shidi and G's is a Hishabi and G's is a Tasheel. From the word I think those who are known who do well they can find out, one is with observation and one table is based primarily on calculation used some other some other persons observation and the last one I am not very sure what is that. G's is a Tasheel is simplified tables for easy application to specific tasks like studying the motion of the moon alone not the whole of astronomy and G's is a Hishabi or Hishab what is familiar to you. These tables presented with the calculated data taking care of various types of corrections and effects in the observed data but it does not involve observation directly and G's is a Rasadi not this is a Rasadi these are tables of raw data obtained from the direct observation. So, these three types of G's were there and there is nothing fundamental in you but the name was this because of that historical connection. The first the no major development in Siddhantic Astronomy took place during this period much much later of course you will find that for the end of 19th century the Samanta Chandrasekhar also developed some new types of instruments and improved the accuracy substantially but otherwise there was no difference. The first major impact on West Asian astronomy was made by the early Siddhantic astronomy as I mentioned yesterday and it was done through the translation of Sanskrit texts into Arabic. According to A.C. Rizvi he quote the foundation of Islamic astronomy started during the reign of Abbasi, Khalifa, Al Mansu in 753 A.D. a copy of Brahmagupta Siddhanta or Brahmagupta Siddhanta it is the same thing was brought to Baghdad from Sindh in 770 A.D. and was presented to Al Mansu. A retention title Sindhan Hind it was translated and name was called Sindh Hind was prepared by Yakub Ibn Tarik and Ibrahim Fajari. Later Aryah Hattiam was also translated by Abul Hussein Awaji into Arabic and the title was Arjavad. Another popular classic was Khanda Khardaka you know it was a corona text of Brahmagupta's Brahmagupta Siddhanta. Now you know corona text were simplified algorithms for direct calculation without going to theory etc. and this Khanda Khardaka was a very popular corona text and that was also translated as Arkand by Yakub Ibn Tarik and these three classics remained as the basis of astronomy in West Asia. According to Syed Suleyman Nadavi though Ptolemy was translated as al-Majisti that is why you call it al-Majist if you now buy a copy of in our library we have it Ptolemy's it is called al-Majist but actually originate is al-Majisti for long and the Arabic astronomers from Baghdad to Spain clung to the Siddhanta genre primarily. Now as Al Birumi was a very important person in the history of West Asian astronomy he lived during the 973 to 1048 A.D. and was the most important person in West Asia astronomical science. He visited India in 1070 A.D. and spent 14 years studying various branches of Indian science and mathematics. Being a scholar in Persian, Arabic and Sanskrit he wrote 27 books on different aspects of India. I have a couple of them. Now he held many Indian astronomers in very high esteem with Brahmagupta at the top. Like Professor C. A. Nalino of Roe mentions quote, the Muhammadan owe the first scientific elements of astronomy to India. These Indian works had many imitators in the Muhammadan world up to the end of the first half of the 5th century of Izra that is 11th century A.D. Till that time it is the transition of Siddhantic texts were taking. Of course what really the progress was made was through observation. They contributed substantially through continued observation which were more accurate and as I will tell you some of the good observatories were developed there much much before Jai Singh developed the observatories in India. Now this astronomy in medieval India, the first this was prepared during 753 to 754 by Al-Fazari based upon Brahmagupta Siddhanta as I mentioned. Important work was done by Mohamad Bin San Ali Kawazmi who fused three contemporary systems like Greek, Al-Majest, Persian, Zizi, Sahariya and Indian Siddhanta and subsequently the most noted astronomer in the Islamic world was Uluk Beg. Spelling is wrong, I think it is not Ulik, it is Uluk. Uluk Beg was the most famous and competent astronomer from Samarkand in the 15th century A.D. This Zizi Uluk Beg had lasting influence on astronomy in medieval India and formal introduction of Zizi astronomy in India was by Il-Tut-Mis, you have heard about Il-Tut-Mis in history in the 13th century A.D. He was the first to bring Zizi astronomy in India and got it introduced in the system here. During the Delhi-Sultanate period, Amir Khushu was also a very competent astronomer and he composed his well-known poem on 28 nakshatras as Al-Manazil. When the first Zizi was compiled in India, the court astronomer of Hiroshath Glock, 14th century A.D. Mahendra Shuri compiled Jantra Raja and Hiroshath Bramani of Deccan was himself interested in astronomy. Actually he thought of constructing the first observatory in Balaghat in the 15th century A.D. but I think it did not come up because there is no trace of it. Taimur's innovation really destabilized whole of North India and all scientific work came to a halt. Only after the beginning of Mughal dynasty, work on astronomy and astrology started with face enthusiasm. Mumbai himself was a very good astronomer and nurtured the growth of the subject. Actually it is told that he failed from this year by viewing Venus and he also had his astrolabe and he used to decide timing, etc., everything based on his astrological calculation. So he failed while observing Venus and going backwards and that fall was quite serious for him as you might have read in history books. Ultimately he died. So Humayun was of course not only an astronomer but he helped development of astronomy. And major calendrical reforms also took place during Akbar's time. Akbar did lot of things and that was another thing, the reform of the calendars. And he also started a new era, not the Hijira but another one and there were around 86 Jesus in his time. And for the first time in India after the Mughal dynasty that means what is in the going time that means the grandson of Alangir, five major observatories were constructed by Jaisen which I will discuss. Discussing more Jesus and this is not much important because they do not have any fundamentally new contribution to astronomy so far as India is concerned. So I think what I will do now that I will discuss the instruments which were used for naked eye astronomy and you have seen the accuracy. See Jaisen's observatories except one wrist had an accuracy of 3 minutes of arc and the biggest one which you see in that is what is the Parliament's study that is that has accuracy of 1 minute of arc. Now this is one instrument which was very popular amongst the vegetarian astronomers even Hellenistic astronomer and it came to India along with the Muslim rulers, astrolabes and they are very popular among the Greek also. But however in Indian ancient astronomy the astrolabes are not mentioned and it is quite obvious that they are not here. So these devices were for astronomical and astrological computations you know. So it consists of number of disks with various markings somewhat like a surplus light rule you know and many computations could be done, calculations could be done and of course the astrolabes just like any sky map you have to see it like this. Don't try to see it like that it will be totally confusing. So just as you see sky it has to be done like that and this is the basic picture what astrolabes represented and the principle of astrolabes was based on stereographic projection of the celestial circles on a plane. So what you do the outer circle here that represents the Tropic of Capricorn. In Tropic of Capricorn means Makar Kranti you know not Karkat Kranti but Makar Kranti. Then what you do you divide by two perpendicular lines north, south, east ways. Now you can easily see you have to view it putting it overhead. Then only directions will match. Then with this O as center and I think what happened this epsilon was I think our 23.5 degrees. The point A was the first point you have to get and this point A was represented by the intersection of the outer circle and the radial line which is drawn and this angle is the inclination of Earth's axis with the plane 23.5 degrees. So after getting this point you join E point and A point where it intersected this S O line at x and you draw a circle with O x as diameter radius and this is the equator. Next what you do after you get the equator then point B and C point B and point C are found out because this circle intersected at this point the line O A at B and you draw a line where this circle intersects line E W that is C join this line then this intersects the line S O at D and then draw a circle with O as center and O D as the radius and this represents the topic of cancer. And when you draw a circle like this this is the then you have to draw another circle with this as diameter this point and this point this is the circle and this circle represents the ecliptic and this is the topic of cancer and this is topic of capricorn and this is the I think equator was this one. So now I think this is just the stereographic projection keeping your eye at the south pole. So this is a three dimensional view I will not go into detail explanation it will take time and I also I have never seen any astrolabe in mind but I see you can see if you go to Jaipur and visit that only thing you know that Jai Singh had a big astrolabe but his grandson or son as you remember he used it as a target practice and Daniel did very much you know for his gun you know he was practicing no interest in astronomy. So this figure above shows the stereographic projection of the celestial sphere on the equatorial plane keeping the eye on the south celestial pole and the main purpose was as you can realize is representing the three dimensional sky on a flat plane. So these instruments look like this you have seen in history book or history of science book it consisted of number of distance. So the main container was called rate A and then team pans these are number of thin number of them for different latitudes each latitude had one with lot of markings et cetera and they used to be kept in the frame and they could they are joined by a pin and they could be moved and with all different adjustments it could make lot of astrological astronomical calculations and computations. The details you can go to internet you can see the website detailed explanation is there how it is done. Actually I will also request some of you if you are interested in this institute things are done why don't you make a good astrolabe here for IIT Kanpur and keep it somewhere I will be very happy if I find it next time when I come make one you can get all the details in the internet of its making and they look like that and I think you know with the help of with your extra knowledge and modern foundation in science maybe you can develop a better one. Another kind of device which used to be used which was also in ancient Indian astronomers history they are called armillary sphere. Now the astrolabe was a two dimensional projection of the sky on a flat plane whereas armillary spheres were actually three dimensional system representing the sky, earth et cetera. So this is one typical armillary sphere I am saying you see even Arya Bhatt describes Arya Bhatt starts saying quote the sphere or Gola Jantra they used to call it Gola Jantra which is made of wood perfectly spherical uniformly dense all round but light in weight should be made to rotate keeping pace with time slowly as earth rotates with the help of mercury oil and water by the application of one's own intelligence. So you can think of you can apply your intelligence and make a device which will rotate with the earth. Now here you see that it was having I have used different colors which is of course not the case. So this is the Gola, Gola means circles represent the earth things and this is the Gola that is the sky. So here you can see that the circles and this is the prime vertical meridian then I think equator is this one. Where is the equator? This one, this is the equator and this is the ecliptic. There are two circles that is 23.5 degree angle is one meridian and this is the axis about which earth rotates. And this is the six o'clock circle there used to be one and this is the south celestial pole, this is the north celestial pole. This is Nadi, this is Zenith. Gola means? Gola means this is the celestial sphere and this is the horizon circle. So these were used even in India and I think if you look into history of science books, scientists sitting in Astroma you will find an ordinary sphere there. So nowadays of course it is often used because you can have much better things with the help of computer. You have seen that how you can have the planetarium software. There are far, far superior software which of course you can buy but the software I have shown you and I am leaving it here. It is free student version and you can get it easily. Those who want I think, request professor Amit Dutta I think you can copy it from here. I am not sure. Someone has to come to my office and take it. No, I am saying that one can copy a software from after it is installed I am not sure about these things. A computer science will be able to tell. This is hard. Because it is already installed here. Can you take it? I think that will be better than that. Now I think I will discuss some. So when we are in the work, he said that there is astro. But I could write, I could write. He said that there was this figure. I could write. He said that there was what I showed in the previous lecture. No, no, no. His main things were actually a quadrant. You will find that in those days, I will show that more or less these are the instruments which I am going to explain now. Even from ancient times, they used to use these as the common instruments. It will look to you not like instruments like children's toys kind of thing but it could give that kind of accuracy you can see. So don't have any disrespect towards these things, you know. One thing is most important instrument is a shanku. It is a stick put at right angles to the horizontal and its shadow of that is to be used for different purposes. For example, if you are asked to find out the true north and true east, how are you going to do it? You can easily do it. Go to the ground and find out the true north and true east and true south. So it is simple what they will do, that they will draw a circle and at sunrise, so after sunrise, the sunrise is here, sometime you will find there is a shadow, some length. After few hours, you again take the shadow and do it in a manner so that the length of the shadow is same.  It will show in the northern hemisphere, it will show the northern direction and perpendicularity of this place. So that is the simplest way. On a sunny day of course, not on a cloudy day, you can find out the true north, true south, etc. And that was primarily what they have done. And so who had other kinds of things and it is not only for finding out the true east, true west and true north, but also as a time indicator for the whole day. That has been, that is why sundial. Sundials are also basically a similar instrument and you will see that our jai-sings, main things are basically similar principle. There is one jasti-jantar, that is a stick. It is only to find out the altitude kind of thing, the angle with the horizon with the particular thing. It could be sun, it could be other thing. But in case of sun, it will be done in such a manner that there will be no shadow at that instant. And this is the angle which is the altitude of the sun. There is another kind of, there are two sticks. One is long, another is perpendicular short. So I want to find out the angle between one direction and a star for example. So I put the main stick towards the direction with which I want to measure the angle of the star and then this way I move this along this till this point and this point aligns with the star. And then this angle will be measured, you can measure. That is, that was used for finding out the, this is shalaka-jantar, this is jasti-jantar. So they used for finding out the angle between a star and a particular direction. It could be another star also. Then we had star, jasti-jantar, again another type of jasti. And this is sakata-jantar. So there is one string and there are two sticks hinged here. So that is also there, you know, how to measure the angle between two heavenly objects like this. A very simple thing, you know, child's play, not even TA-101 level thing. So these are called chakrasantra. So this chakrasantra, they are used by Arya Bhatt also. So this chakrasantra was a hook and diametrically opposite, there are two holes. So you put it on a horizontal plane, you rotate the plane of the hook about a vertical axis till it matches with the plane in which the sun is contained. Then rotate the hook without changing the plane so that the sun may pass through the two holes and falls here. So then using the dimensions etc., you can find out its azimuth and altitude, all those things you could measure. Another one is of course that from the two ends there are two hanging strings and it is held in hand and from the length of the strings you can find out the angle. Just variation of the same principle, of course. Chakrasantra, again some more chakrasantras. So here the vertical is indicated by a pendulum kind of thing. That is what our plum or plumbers do, you know, use.  And this angle, we will call the zenith distance or the angle it makes with the vertical and so on. And here this pin is here and this is a disc which is hanging vertically and then this shadow wherever it falls, so it will automatically, this is a perpendicular line to this and which has to be vertical because it is hanging. So this used to be called as the altitude, obviously. And this is dhanur jantra. This is like a semicircle or dhanush. So you put one diameter on the horizontal flow and rotate it so that the, it matches the plane of this dhanush, matches with the plane of the sun and there is a pin here. You shift the pin along this till the shadow of the pin falls at the center. So therefore this, I think, gives various things like this is the best circle. So you can get the angle, altitude of this and also this is the sunrise point is just like that. So this is called dhanur jantra. These are other types of dhanur jantra. Here it is a semicircle and there is a plum and this is one of the radius perpendicular to this. Now you align this side diameter with the star, with your eye and measuring this plum location here, you can see that what is the angle and that is the altitude of this star. Obviously because if this is a plum, it has to be vertical. Similarly here also you will find, you know one thing you have noticed perhaps in some cases I am showing sun, in some cases it is star.  Say of course you cannot look at sun like this, you know in no time you will become blind. You know that when we are asked not to look at solar eclipse, it is not any religious stigma, it is dangerous. The reason is very simple, that when the sun is full, you cannot look at it. It is so bright, you cannot your leaves will automatically close. But when there is only a crescent of the sun, you can very easily look at it. It is so nice to look at. But the image which is formed on retina of that crescent of the sun, its intensity is the same. So it damages the retina. This is proven fact and that is why it is said that not to look at. Because you can easily look it is a very thin line or diamond ring all kinds of things are told, you know. But the image which is formed it is as dangerous as the real full sun. So therefore whenever there is some kind of thing, it is always a shadow. There is a pin here so the shadow is cast here and you can say this is the altitude. These are all variations of the same thing. Now this is Bhagana or Narivalaya Jantra. As you will see even Jai Singh did this. Narivalaya Jantra, now this plane, this plane is actually parallel to equatorial plane, you know. And this is a pin perpendicular to this at center. And here the shadow, you know on the equinoctial day shadow will not fall or it will fall on both sides. And in the Tarayan period you will find when the sun is on the north then shadow will fall here. When the sun is towards the south then shadow will fall on the other side. And this way you can find out all dimensions measuring its angle and all those things. You will see more detailed Narivalaya Jantra constructed by Jai Singh. This is called Kartari Jantra. These are all variations. Kartari Jantra is again two semicircular discs at right angles. One is east-west, one is north-south and if you point it to the north pole, you know and this will be the east-west measurements and the markings are there, shadow etc. This is also a type of Kartari Jantra but this Kapala Jantra is interesting. It is nothing but a huge bold hemispherical bold and at the top there are two cross this are two thin wares at right angles, at two diameters and so this point is the center of the surface here and inside surface of this hemispherical surface they are given all kinds of markings. Then when the shadow of this crosswear falls on that looking at the location of this point you can get many things like time, altitude everything you can get to know. So these are called Kapala Jantra. Now you see I come to Sai Jai Singh and a little bit of his life which is very interesting. Now Jai Singh the Raja Swai Jai Singh of Angar he was born in 1688 and lived till 1743. Now we have told that his position is very unique but also I think there are some unfortunate things you know. So whatever the Euro-Sentic Western scholars might find a chance of observation in ancient Indian astronomy but there are ample evidence as you have told Shupa. Now what happened that when Jai Singh inherited the throne of Ambe after his father Vishnu Singh died in 1780 at the age of only 27 at Kabul. He was fighting along with the Mughal in the decline and to control the Marathas engaged in constant guerrilla warfare in the Deccan Jai Singh was sent by Aurangzeb to the south. Jai Singh was only 14 years old at that time. There when he was in the south he met a young mathematician and astronomer Jagannath and that friendship was a lasting friendship with everything. So what happened as such the foundation for a lasting friendship with him was laid and after Aurangzeb's death in 1707 when Jai Singh was still in the south the political situation in Delhi became very uncertain. The whole thing was being controlled by actually a group of people they are called council of Amir Swaram Rahim and then Aurangzeb's great grandson Muhammad Shah as the emperor Jai Singh was on a relatively good terms Aurangzeb of course was very old you know and served him in various capacities though even with Jai Singh's control was over in his native area Amir that measured no more than 7500 square kilometer by 1730 his authority extended to a much larger territory from Delhi to Normala in fact during that period Jai Singh enjoyed more power and respect than the emperor according to a French Jesuit traveler. Now observators of Jai Singh which is our interest so whether Jai Singh had more interest in ruling a kingdom or perjuring astronomy is not known but he knew Arabic and Persian and as well as Sanskrit and was quite familiar with Islamic Siddhantas. He had a number of astronomers in his court the most important among them was of course Jagannath and who translated Al-Pussi Arabic version of Talimi's Al-Majest into Sanskrit under the title Sambharata Siddhanta his other court astronomer was Ray Kebaljum from Gujarat and he wrote a dozen books etc and Jai Singh also compiled a jeez called Ii Muhammad Sahi in the name of his friend Muhammad Sahi but actually it was nothing but these days it will be called plagiarism what he did was Ulugbeks jeez actually now interesting thing is that he was at a time when Copernican theory etc was there was known but he was unaware he thought that he checked all the tables he was finding the results were not accurate enough and he thought that this non-accuracy is due to inaccuracy in observation he never suspected that our model of this system of the universe was wrong so he thought his main concern was Ticrobial like Ticrobial to improve the accuracy taking instrument with small wood or metal pieces they are subject to many distortions he thought he will make observatories using machine with stone concrete or something like that and that is how and he wanted to make them big and that is why actually there are quite a few observatories he set up and primary aim was improving the observational accuracy and these are known as Jantar Mantra which originally called Jantar Mantra Sanskrit term in Delhi it was constructed during 1720 to 24 and there are 7 major instruments in Jaipur the construction was from 1728 to 1734 and there are 14 major instruments Varanasi 1724 and there are 5 instruments with Jaim there are 1730 there are 7 instruments and Mathura 1734 there are 5 instruments so these 5 Jantar Mantras were there in Varanasi I think the Jantar Mantra of the observatory was erected on the terrace of Manmandira that was the name of a palace constructed by Jai Singh's ancestor Raja Man Singh and that is why today astronomical observatories are called Manmandira in India or Hindi isn't it and that originated from that the Varanasi observatory was erected on the roof of Manmandira was the name of the palace so we call astronomical observatories also as Manmandira now you see that though his objective was to improve accuracy by having bigger system made of stone and machinery etc so the accuracy of Ulupeg's observatory erected 3 centuries before Jai Singh had the same accuracy Jai Singh's observatory instruments as I mentioned had plus minus 3 minutes of arc accuracy and he is the largest one the Samarata Jantra which I will explain and discuss it had plus minus 1 minute of arc accuracy which is better than Tycopa here and that is also considered the limit of naked eye astronomy instrument where you can sextant eye so there actually which one was 1 minute of arc accuracy accuracy that means suppose you are measuring the angle between 2 objects or you are measuring the altitude or measuring the the azimuth whatever it is any angle because astronomical observation is nothing but angle measurement there is nothing like distance it is only angle so the actual value and the accuracy with which you could measure it that is the use so that is why here we say it is like this but in real life it is not that simple they are all genius to make the accuracy so I am told that in reading they used to take very accurately and there is to be large number of assistants also it is not impossible to handle all those things by one person so Tycopa also had a large number of assistants same thing with Jai Singh they had large number of assistants no I understand that one gear kind of thing like your micrometer principle was discovered in towards the end of 19th century so I think this is very unfortunate thing you know and why it happened why Jai Singh did not it was there, couple of things were there the heliocentric model concept by Galileo you can see Galileo and Jai Singh they are contemporaneous isn't it Galileo was born in 1565 or so and died at 1642 and Jai Singh's date I told was 1688 actually he was after Galileo almost at the time of Newton so I think why by that time gravitation law etc all are known the reason is there he at that time interaction with the west started and lot of jesuit priests used to come from Europe and Jai Singh and they used to bring I think all knowledge of west I think European astronomy and Jai Singh took lot of interest in that and he used to depend quite a lot on them so once he sent a team to Spain I think or Portugal I don't remember he used to bring more information more modern information now all the jesuit priests were very much against heliocentric model you know that that's why George and Bruno was burnt alive Galileo was put in jail so they did their best to prevent Jai Singh in getting active in heliocentric astronomy so that's why Jai Singh depended on them so much on the modern development but they almost isolated him from the development but it is told that Jai Singh had a telescope I'll read it later and he had something which is not known but I have read in a history of science book published by your India National Science Academy this I also didn't know I'll tell you here I could tell it later but it is better to tell and Jai Singh knew certain things and perhaps did some experiment with telescope that need to be done so SMR Ansari he is a scholar who deals with the history of astronomy I have read his paper and he reference to Jai Singh's knowledge based on telescopic astronomy are found on the following topics the electricity of the lunar and solar orbits the existence of four Jovian satellites obloid shape of planet Saturn because at that time the ring was not clearly visible you know Galileo saw it first he first thought that planet has two years and you know in those days the scientist used to do very funny things he observed something and then he thought whether to publish it or not he thought that if it is something stupid he should not publish it because there was so much of acrimony and other things because of the paradigm shift was taking place so what he did he sent a secret message which could be deciphered as the discovery of Saturn these two bulges and sent it to some other scientist hoping that when later it is discovered and it is found to be true he will claim his priority but after sometime he was horrified to see that those bulges are gone so he was so scared that then again after quite a long time what happened actually he shattered the ring planes at that instant the plane of the ring was coinciding with our line of vision so we could not see the bulges the rings are very thin you know so if you are looking along the edge of the ring you will not see them that is precisely happened at that location Saturn's ring plane was matching with the line of vision but again after sometime those bulges reappeared and then he told that I have observed these please and also it was a new discovery a planet with ears and later he found that there are two circles but he didn't know that they are rings so therefore the obloid shape of planet Saturn was the kind of knowledge they had and phase of planet Venus and Mercury so why Jai Singh did not pay too much effort and attention to telescopic observation there is another theory because with telescope at that time was a qualitative measurement till the cross wire was invented and attached to telescope it was not a measuring instrument it was just like a binocular kind of thing once the cross wire thing was developed it started giving numerical quantitative factors so telescope was not very useful as a his objective was to have more accurate observation that means he has to get measurements with telescope measurements were not possible at that time secondly the heliocentric model of Gokernikas the results were no better than the deocentric model of Ptolemy so there was no impetus on Jai Singh to really go for heliocentric model but I don't know where answer he found this but he says that these are there in the writings where Jai Singh he had a telescope and he had these observations I will now discuss something about Jai Singh's instruments developed by Jai Singh this is the most important and most prominent instrument you know samrat jantra and you have seen that it is nothing but a equinoctial sundial kind of thing equinoctial sundial something like that naribala jantra that a plane which is parallel to the plane of the equator that is sometimes they are called equatorial sundial that is the same thing and then there is a shanku and the shadow falls on that so here you see what was the samrat jantra's basic principle that this is thin it is like a set square you know a thin slab vertical and this angle is equal to the latitude of the place in the location and it is oriented towards in the north south direction exactly and then perpendicular to this plane there was a circular path q east to q west and from here then what happened and this was a solid thing so when sun comes the shadow of this edge will fall at some location here and that will tell you the time accurately have you gone to Delhi to see jantra mantra you have seen the markings on marble there so if the sun is there this will cast a shadow on the quadrant in the morning the shadow will be on the western quadrant and in the afternoon it will be on the eastern quadrant obviously and that will give you the time of the day just like a sunrise again there is a rod here which you can move along this and there are markings so this rod you are moving till the shadow of the rod falls at this point and the marking here will tell you the altitude of the sun so primarily the time and altitude of the sun these are the two things you can get very accurately with an accuracy of 1 minute of art size is big I am telling you its size is height of that end height is 22.6 meter so it is 6 to the building I believe the accuracy comes obviously so this is a 6 to the high building height 22 meters 22.6 meters the daily that daily it looks like this and as I mentioned that the declaration north and declaration south to find out right ascension and declaration I told you in the equatorial system so you have to shift this rod along this and when the shadow of the rod falls here this angle is the declaration and that is marked here so one thing is very clear the marking or engraving has to be non-linear it is not linear you can see that so 45 to 60 is so much 30 to 45 is so much and 0 to 30 is only this much so marking if you go to Delhi now the actual shape of samrat jantra is something like this isn't it and let me see the photograph I have one this is the one I am talking about this jantra that is a 6 to the building and actually this is a smaller version these are the quadrants eastern quadrant western quadrant and the steps are there because somebody has to go up and down yes this angle if it is inaccurate obviously everything will be inaccurate but it is obvious because you see it is equatorial system that means this this you know these are parallel to equatorial plane okay and it has to be perpendicular to that so anything which is perpendicular to that it is nothing but the shanku like yeah it is nothing but equinoctial sandaya just that very large size so if it has to be perpendicular to the equatorial plane that means it has to point towards north pole isn't it and this angle has to be latitude measuring latitude is a relatively simple problem that is a relatively simple problem yes so I think they had for that tables etc they all had that so that means depending on the season you know what is the declination everything will change of course and actual shape is like this you know I have gone one long back you know these days only I pass by that parchment street somebody is giving dharma and all kind it is used for that purpose I believe these days and if we take there I think it is not allowed to take food inside or is it earlier it is to your picnic spot I remember in 62 when I was there so these are the gyacin's observatory for naked eye astronomy there are various jantras other jantras as I mentioned kapala and gyaprakasha jantra the kapala jantra this is a huge bowl and I explain this and these are the two wares or ropes this acts as a cross wear and inside their markings are there where the shadow falls and from the shadow the marking gives that what is the reading and somebody will go inside and will see the size of this kapala jantra in Delhi I think the diameter of the this jantra in Delhi in Jaipur Delhi is 8.3 meter about 25-30 feet that is the diameter next is digamsa jantra digamsa jantra is used primarily for measuring the azimuth angle of the heavenly objects and it consisted of two concentric circular walls with a central pillar I have shown that here this is a central pillar those two circular walls and there are two ropes one is east-west direction one is north-south direction and another rope with a hanging weight here so you can when you want to view something of a star so then you have to move this along this till this and these are in the same plane and this angle is given as the azimuth angle so the size of the jantra here in Delhi it was built only in Jaipur Varanasi and Ujjain Delhi it is not there and the wall height was this was a three-storey building this height and this height was just slightly less than one storey so this was actually a three-storey building so it will look like a huge circular enclave and this is the cross section how it is this is height h this is h by 2 this is the sectional view but in not all cases it is h by 2 in Ujjain it is different as I can see but these are all pretty big machinery works as Jaipur he wanted higher accuracy but the accuracy unfortunately was not more than that of Ulugbeg which was constructed 300 years back these are two important jantras, Nadi Varanasi jantra these are again nothing but equinoctial sandayals two one on the north face another is the south face these are parallel to equatorial plain and this is pointing towards north pole this is pointing towards south pole looks like this and again a dial is there so it is for measuring the time and identifying the equinoctial points equinoctial day what will happen that it will be exactly parallel and both will cast shadow so that day and other days only one side will be having the shadow on the next was Ramajantra so and this is Nadi Varanasi jantra in Jaipur the plate diameter was 3.6 meters that means how many feet 12 feet kind of thing 11-12 feet and the separation was about 16-17 feet and Ramjantra is Ramjantra name was given perhaps after his grandfather Ram Singh many people think that way and the instrument was in the form of a cylindrical structure with open top and a pole with the same height as the surrounding cylindrical walls and the floor and the inner cylindrical surfaces was engraved with scales indicating azimuth and altitude very simple to follow so there is a pillar here and these are all vertical line scales and here they are radial lines so when there is some the shadow falls here and from that you can easily find out the azimuth looking at where it is falling vertical when it is going here so you can measure at a time measuring the shadow and its location and the reading you can get both azimuth and altitude these are the main things these angles you know astronomy is nothing about measuring these angles so Ramjantra is size let me see if it gives yes in Ramjantra was constructed only in Delhi and Jaipur wall height and the radius for Delhi Ramjantra about like a two-storey building it is 7.5 meters the accuracy for both of this the order of 6 periods of arc all the marking so 6 minutes of arc accuracy you had in this Ramjantra then the most famous and most attractive Jantra is there which is generally photographed and this is really astronomical it was never used very much and neither it gives any better result that is called Mr. Jantra small thing the diameter of the sun is about 20 minutes or so no 30 points some 30 minutes so 6 minutes means one side of the sun only one side they were very careful about when they touch one side comes then only they do so then so the Mr. Jantra in this photograph many places it is a very attractive structure and most photograph structure so far as this Jantar Mantra is concerned but it is not really very useful it was a combination of various Jantras you know it combined Samrad Jantra, these Jantra and quite a few others and observationally it was not very important neither was it very used only it was a kind of nice looking sophisticated thing and I think your also pretty big I do not remember the sizes are not given here I think the scale is here so this is 20 feet as I have given the scale so you can see this whole thing is about 100 feet kind of thing it is a pretty big massive thing this is one of the this is one of the this is another symmetric thing this is another quadrant and this is a myth chakra I do not know all kinds of changes now I think you know Jai Singh's aim was to rejuvenate Indian astronomy rather than really pursuing the truth and unfortunately he could not achieve a clunk to the geocentric model to bring the wisdom from Europe he chose a wrong country Portugal for sending his envoy not Italy thus hardly any modern idea was brought back to him he also spent money and effort on building perpetual machines that took lot of time and effort it was said that an amount of equivalent to US dollar 25,000 was spent by him on experiments in that direction constructing perpetual machines even though Jai Singh was born after Newton's Principia was published Jai Singh's astronomy remain archaic in character he had the telescope but it did not occur to him to use it as an astronomical instrument the reason I told you it started becoming an instrument only after the technology of crosswear was developed in so he died in 1743 and his second son Mahjoh Singh demonstrated some interest in astronomy in fact it was he who built the Mishra Jantra of them that of course many may not know the Mishra Jantra was constructed by his son and that's why it didn't have much astronomical importance and he had the opportunity to become a pioneer with his resources his interest in astronomy he wonderful assistant like Jagannath but I think he chose the wrong people and the result was this the last one in the whole history of siddhantic astronomy was Samanta Chandrasekhar of Oisa he was born in 1835 and died in 1904 so you can see it is a very recent thing he was even in the 20th century and the last siddhantic taste was written by him this is called siddhantra dhaktana it had 24 chapters and had 2500 slokas out of which 2284 was his own compositions and he was definitely very talented person and in seclusion he grew up so he was unaware of the happenings you can see by that time in India itself his telescopic astronomy was quite prevalent but he clung to the same old siddhantic astronomy and naked eye astronomy so the in spite of that fact of course his siddhant dhaktana he noticed the inaccuracies and he tried to improve the accuracy and you can see the improvement which is very apparent here these are nothing but the inclination of the planetary orbits according to the various siddhantas the planetary orbits you know various planetary orbits are inclined to the ecliptic plane as I mentioned so that angle is very important to make good estimate and good correction so you can see the five planets you know here and along with moon they are inclination to the ecliptic plane in Surya siddhanta it is moon 4.3 degrees in siddhanta 0.8 is 4.3 siddhanta dharpana 5.09 and actual modern value is 5.0833 so you can see the substantial improvement which is the correct value and siddhanta dharpana samanta chandrasukha is this whereas the old values were quite inaccurate so when you go to mercury which is very difficult to observe mercury is so near sun extremely difficult to observe Surya siddhanta gave a value of 5.55 siddhanta ceremony gave 6.55 your siddhanta dharpana gives 7.02 and here you can see it is 5 degrees 0.9 I must say you should keep that in mind up to minute of arc, second of arc you can ignore so 5.09 means 5 degrees 0.9 minutes here it goes up to second modern value of course so 7 degrees 0.2 minutes siddhanta dharpana was so accurate here it is 7 minutes and 0018 18 seconds so I think it is very clear that he made tremendous improvement in accuracy with his instruments also simple nekera instruments which he designed he constructed he did not have any instrument like jai siddhanta no all the hand held so and you can see the improvement in accuracy so his his life history you can find in the book I am not reading it so his instrument his own observational instruments is developed of course they will resemble some of the instruments in siddhanta takes but one of his instrument called monajantra it is very interesting you know it looked like I am unable to resist the temptation how it looked so these are serrations with different angles you know this was his own invention because no such instrument is found in any siddhant he called all the texts and with this monajantra was his own invention it was a multipurpose instrument that could measure you see latitude, altitude genus distance, suns declination, angular separation and the suns position in the zodiac and this instrument in the form of a T as I showed and crossed up was engraved with 24 slots with progressively increasing inclination and it could do so much with such accuracy he also designed chapa jantra for measuring time and gola jantra and that was also similar to kapa jantra like that so his siddhanta darpana is still in use in orissa because all things puja, sacrifices, etc in jagannath temple they are all guided by samant chandrasikas calculations and not only there but even in the society of orissa most of the households panchang prepared following the siddhanta darpana even till today so however the fact remains that he was very much in the telescopic era but he devoted his whole life actually he was not known then one I think it is sometimes just for the sake of the story you should know some of the chandrasikas were represented more as an astrologer people thought he was an outstanding astrologer he was a gifted astronomer and he was born in 1835 as I have shown in khandapada 100 kilometer west of Bhuvaneshwar it was a small state surrounded by hills and jungles samanta was born in a royal family when his uncle ruled this small state his early education was primarily in Sanskrit and Sanskrit based literature at the age of 10 his uncle introduced him to the basics of astronomy and samanta himself learnt the siddhantika when he was 15 he wanted to check the astronomical predictions of siddhantas through his own observations with the instruments made by him to his utter dismay samanta found the predictions to fail in predicting correctly the positions of the planets and stars repeated checks finally convinced him that established texts like shurya siddhanta siddhanta siramuni needed further correction then he took it as his life's ambition to incorporate all the necessary corrections in siddhanto astronomy amazingly he designed his own instruments for naked eye astronomical observations yielding results with much better accuracy starting at the age of 15 samanta chandrasikas began his astronomical observations and theoretical analysis for the next eight years reaching the age of 23 samanta started systemizing the huge data collected by him and at the age of 26 he started writing the text compiled by him the last siddhantic text siddhantadapati he wrote the book in oriascript on palm leaves because of his isolation from modern educated world the text remained confined to a corner of his house for 30 years on his chance meeting with Prof. Mahesh Chandra Nairatna principal of Sanskrit college Calcutta during one of his Orissa tours Prof. Nairatna was greatly impressed by his talent and it was Prof. Nairatna who introduced samanta to Prof. Yogesh Chandra Roy of Patak college present there Avinso college who played a key role in getting the siddhantadapati published in Debnagari script from Calcutta in the year 1898 only after this the outside world came to know about Samanta Chandra Siddhartha and his valuable work so that is the end of siddhantic astronomy in India and I think tomorrow the last what I will do I will give some interesting very interesting and in the history of astronomy they have remained as a fascinating stories with tragic results sometimes they are not tragic stories you will see and the beginning of telescopic astronomy but major part of tomorrow I will also discuss the whatever the recent research tells about the antiquity of Indian astronomy and also the originality how much of it is original and some discussion on the controversies about the originality of nakshatra system different scholars view and discuss that I will not discuss much about the development of radio telescope etc in India that is a modern period and that is not the objective of this because they are all current things going on so I think if there are few questions we can discuss that this Jyobesh Chandra Rai is he the author of this book on Bengali book on Jyotishi do you know probably he is who have done lot of work in the 19th century was Kalinath Mukherjee was one and 20th century I have told pieces and books and others but in the previous century Kalinath Mukherjee was actually you know inspired by Herschel's grandson he was a civil servant in the district of Nodhya where and he taught Herschel's grandson Kalichar Mukherjee and he was a lawyer and he has astronomy at his own so how is the story of Siddhantic astronomy I think it is very interesting you have you have already found out you know we are discussing about the Katapaya system so he has worked hard and he has found out yes that slope gives the value of pi I think it is that Shankaracharya Puri Shankaracharya who has also written that Vedic he has given that so was there interaction between mathematicians and astronomers actually same thing mathematics a lot of development trigonometry and other things on astronomy and astronomy also a lot to mathematics and since Indian mathematics was most developed so it is obvious that our things will be superior to others so one more question so did their school come to them was some system built especially for R. A. Bhatta they had disciples obviously they had disciples the whole subject I think there are thousands of astronomers who have worked we have presented only small miniscule fraction of that even I have not been able to discuss who are the very famous astronomers you have shown the picture no one has used magnet as a what what no one no one has used magnet for what magnet does not give you accurate reaction at all magnetic is not magnetic north also varies from place to place from time to time you are interested in the celestial pole to north not the magnetic north north is different from the true north it was known to Kepler actually at that time his name was Gilbert who wrote the first book that was at the time of Kepler and from that only Kepler got the idea of gravitation the idea of gravitation first came from Kepler and he told that every object attracts every object and they move towards the common point the amount of movement depends on their relative bulk so it is Newton is not the originator of gravitation theory this is part of his three books Kepler's idea of gravitation is not part of his book is it written in the book Kepler's idea of gravitation you can even get it it is all very clear only thing problem was he thought that gravitational force the force was proportional to velocity everybody the concept of accelerating and linking with force was first by Huygens that was the real breakthrough he showed that force is proportional to acceleration and the constant of proportionality was N that was Newton the omega square r was known to Huygens he developed it and using that and Kepler's third law they found out that the gravitational force is inversely proportional to square of distance by Halley and Hooke that was also known much before Newton okay any other questions okay thank you


What's happening? It's Shane here. And in today's video, we are going to be talking about the top 10 bachelor's degrees for 2022. Right? So I talk about all different types of careers and college degrees on this channel. But in today's video, I'm going to be focusing on bachelor's degrees. Now, bachelor's degrees are my favorite type. I think that you get the most bang for your buck. You get the best return on your investment with these degrees. But with that being said, some of them are better than others. And in today's video, I'm going to be talking about the top 10. In my opinion, after I've done a ton of research, and I'm even going to be including my version 2.0 of the college degree ranker. And I can tell you without a doubt, this is the best possible resource on college degrees that has ever been created. Usually only my college 101 students have access to this, but I'm actually going to be sharing the rankings today in this video. So stay tuned for that. So let's jump right into it right after you gently tap that like button, hit the subscribe button and ring the notification bell. Number 10 on the list is going to be a technology related bachelor's degree. And that is going to be information technology. So this could be information technology or information technology management. And about 9,000 people graduated with this degree last year. Now when it comes to the statistics, you're going to make about $55,000 a year starting out and $92,000 in mid-career pay. That's pretty good, but it is one of the lower salaries on the list. However, you will likely be working in the technology industry, which has a lot of benefits. So a lot of the time you are going to be getting bonuses, stock options, quality of life is going to be relatively good because your job satisfaction is going to be pretty high. And there's also a lot of other just random benefits that you get a lot of the time when you work in tech. Now when it comes to the demand score, this one is actually the second highest on the entire list. The demand score is 137. Now, when we were designing this degree ranker, we decided to put the demand score, the top rank at 100, but there were certain degrees that were just so good when it came to demand that we actually expanded it above 100. And this is one of them. The other degree on the list that has a demand score that's even higher is another technology related degree. Go figure. But yeah, this can be a really fantastic one. One thing I will say about technology related degrees and careers in general is there's a little bit of an asterisk right next to them because of the fact that there are multiple different ways of becoming, for instance, a computer programmer or a software developer, a really safe way of doing it is to get your computer science degree. That's a great way to do it. There's nothing wrong with doing that at all. However, in many cases, there are easier methods of getting into a lot of these different careers like information technology. That doesn't mean that the degree is bad. It just means that there are alternative ways depending on your situation that you might be able to pursue. Number nine on the list is going to be a good old health care degree. And that is going to be nursing, a BSN or Bachelor of Science in Nursing. This one starts off at $60,000 a year and $79,000 in mid-career pay, super flexible degree, tons of different career paths you can go down. The demand score I believe is the third highest on this list at 135. And the meaning score is a fantastic 83%. I believe that's the highest on the entire list. And that tends to be a very good indicator of how happy you're going to be with your career long term. So yeah, nursing, fantastic option. One thing you can do with nursing is let's say you want to get more on the business side of things. A lot of the time you can move up in hospital administration. Let's say you want to get more specialized training, you can get your masters become a nurse practitioner, which is another fantastic career. If you want to get even more specialized training, there's going to be different options like you can get certified to become a nurse anesthesiologist. And if you want even more specialized training, you can get your doctorate in nursing as well. A lot of options for you, always nice to have a career and a degree that is extremely flexible, you would have to work within the healthcare field, but there are a lot of options there. Number eight on the list is another degree that is super flexible. And that's why I included it on the list. And that is going to be mechanical engineering. This is going to be the first engineering degree that we talk about. There's going to be several on the list, no surprise. And this is probably the most flexible engineering degree. So last year, about 32,000 people graduated with this degree early career pays 66,000 mid career pays 110,000. So the salary there very nice anytime you can get above six figures, that's good. The demand score is 105. So very good. It's actually one of the lower ones on this list, but that's just because this list is chuck full of like super, super good degrees. The next one on the list is also going to be an engineering degree. And it's also going to be very flexible as well. And this one is kind of a dark horse candidate that I have seen just get better and better. And I'm extremely bullish on its future. And that is industrial engineering. Last year, about 5,000 people graduated with this degree early career pays 67,000 mid career pays 110,000 according to pay scale. And the demand score is 101. And this is another one where you're going to be learning those engineering skills, you're also going to be learning a lot of business skills as well. That is just a really, really good combination. Speaking of business, that's going to be the next one on the list, management information systems. Now, this is one that is relatively new, only about 7,000 graduates last year. Now there's two things that I have to assume with this list. And this is something that I didn't necessarily assume in previous years. The first one is that difficulty doesn't matter, right? So if you choose a degree and something that you're really passionate about, chances are you can figure out a way to get it done. Maybe it takes you an extra year, but that's totally fine. If you're passionate about it, you will persevere, you'll figure out a way to get it done. So I took difficulty out of the equation. If difficulty was added into the equation with this year's list, engineering degrees would rank lower because there is a pretty high dropout rate. With that being said, I pretty much took it out of the equation. But if you're somebody who wants a degree that's maybe not quite as hard, business degrees do tend to be easier when you compare them to a lot of the really hard ones, like engineering degrees. And management information systems is fantastic. So it basically combines business skills with technology skills. So with this one, you're going to start off about $60,000 a year and mid-career pay is going to be $105,000. So super good salary score. You would likely work in the technology industry, which has all those benefits that I talked about earlier. It's also incredibly flexible. You can work for just about any company and any industry in a ton of different positions. Now the demand score is a very nice 113.61, but check this out. 7,000 graduates, 39,000 listings had the keyword management information systems degrees in the listings themselves. So 7,000 graduates, 39,000 job listings, that is a very good sign. And that's one of the reasons why I am so bullish on this degree. It's very good now. And I think it's going to be even better in the future. Number five on the list is not going to be a specific degree, but it's going to be a degree tracked. And that's going to be pre-professional degree studies. Now this isn't going to be like all professional degrees, right? Because some of them aren't as good as others. A lawyer is one example of one that's kind of saturated. It's not quite as good anymore. Very competitive as well. However, there are many professional degrees out there, medical doctor being one of them, where there is a pre-med tract or a pre-pharmacy tract or a pre-this or a pre-that tract. So one example would be physician assistant studies, somebody who is taking the classes needed to become a physician assistant, now known as physician associate. And as a physician associate, you would make about $115,000 a year. And there is ridiculously good demand for this one. It's about 31%. The average is around 4 to 5% growth over the next 10 years. So it's like six or seven times higher than average. Really, really good option. Again, some of the professional degrees are better than others. One way that I like to explain professional degrees is they're almost a combination of the trades and then a traditional college education. So you're getting the degree in order to do a very specific job or a very specific career, just like you would in the trades. But it is also something that does require that in-class training. And just like trade careers, professional careers, professional degrees do tend to pay very well. Number four on the list is going to be another degree that's relatively flexible. And that is electrical engineering. About 16,000 people graduated with this one last year. And many of them are going to end up going into the technology industry, which I mentioned before. Fantastic industry to work in. You're going to start off at $70,000 a year. Mid career pays about $119,000. And the demand score here is $109,000. So again, very solid. This one is also relatively flexible compared to the next one. Now, this is where I talk about the second thing that I have to assume whenever I'm making these videos.  So one danger of going for very specific degrees is sometimes you end up changing your mind. And there's nothing wrong with this at all. Things happen in life. Maybe you meet someone, you get married, you move somewhere, you know, you have to find a certain type of job because, you know, jobs are only a certain way in this place and your degree doesn't work like that. All kinds of different things can happen. And so a lot of the time it's best to just stick with a more flexible degree. However, with that being said, if you've really done your due diligence and you know exactly what you're going for, going for that more specific degree can be the better choice. So if you're not 100% certain which one you're going to go for, but you know that you maybe want to go into the technology industry, electrical engineering can be a very good choice. However, the next ones on the list are slightly better if you know exactly what careers you're going for. Number three is going to be computer engineering. This one had about 7,000 graduates last year, starts off at 72,000, 120,000 mid-career pay. You'd also likely work in technology. This one tends to be more on the hardware side of things, although many computer engineers end up working in software as well. And this one does actually have the highest salary on this entire list. And the demand score is also very, very good at 107. So yeah, really good option. Next one on the list, very similar to the previous two, that is going to be number two, software engineering, starts off about 69,000 mid-career pay is 112,000. So very good pay. The demand score is I think the third or the fourth highest on the list, super, super good at 127. However, check out one thing here, there's a thousand graduates per year. However, there is 77,000 job listings that mention software engineering degree as a keyword. And usually I use either monster.com or indeed.com to look these up. That is absolutely insane. And that is a sign that this is a skill that is not only good now, but it's going to be even better in the future because there's so much demand for it. So I wouldn't be surprised if the demand score goes up five to 10 years from now, not down. It seems to be on an upward trajectory, not the other way around. And honestly, the only reason this one isn't number one is because number one is just a little bit more well known. And that is of course, computer science. About 22,000 graduates last year for this one, pay very nice $68,000 a year starting out 114,000 in mid career pay. And there is a 153,000 job listings that mention computer science degree. That is a demand score of 154, highest demand score not only on this list, but on the entire list period. So yeah, ridiculous demand, ridiculously valuable skill to learn computer science and programming is one of the few skills where one person can, you know, write some type of code, creates, you know, some type of software or a website, etc. that can reach millions of people. So it has basically infinite leverage, there's not that many skills out there that have infinite leverage, creating videos is another skill, maybe marketing sales ish, maybe kind of is another one. And that's about all. So yeah, content creation, learning how to code and sales slash marketing skills, those are pretty much the three only skills, maybe you could say optimization as well, like optimizing a business optimizing and growing a business entrepreneurship, yeah, just a few skills have the ability to basically have infinite leverage and computer programming is one of them. Hope you enjoyed this video, check out my other ones right here, I made them just for you, go ahead, gently tap that like button, hit the subscribe button, ring the notification bell and comment down below any thoughts, comments, criticisms, etc. that you have on the video and I will see you next time.


Hi, my name is Mara, I work with my work primarily focuses on power management and thermal management frameworks in Linux kernel. I will let my co-speaker Ram introduce himself. Hey everyone, this is Ram, I am from Qualcomm and I actually come from Power and Thermal Software team. So I specifically work on thermal software solution for all Qualcomm Snapdragon chipsets starting from Linux kernel all the way to proprietary Qualcomm thermal demons in the user space and Android world. I don't think we could hear Ram. Okay, so I don't know, I somehow couldn't hear Ram. So anyway, so this session is about why some modern SOCs cannot handle lower temperature, really low temperatures by low temperatures. I mean, zero degree Celsius or below. So Ram will walk us through some of the hardware issues we face at these temperatures, and then I will take you through the how to extend some of the Linux frameworks to handle these scenarios today. So over to Ram for now. Hey everyone, so let's straight jump on to the problem statement and like you know what's the problem that we have in the hand. In order to understand this problem, we need to understand this concept called time enclosure. So if you take any logical circuit, we know like you know it's going to be comprised of different gates and individual gates are going to have their own delays. And when you put together like you know all those gates in a logical circuit, the total delay that the logical circuit is going to experience to convey an input all the way to the output is going to be an accumulated accumulation of all the delays that are actually involved in those individual gates. So when you're actually designing a logical circuit, this becomes important concept where this particular total delay of this logical circuit should be always less than the time period of the synchronizing clock pulses. If that is not being met, you would actually start seeing this logical circuit like you know, start to behave like you know unexpected, you know, if you will see an unexplained behavior or like you know any unexplained logic that will be happening there. So in order to ensure the correctness of any logical circuit, this timing closure has to be met. And this is actually like you know kind of a widespread concept which is prevalent across all the process nodes like starting from 28 and like you know all the lower processing nodes. We have this issue and in order like you know pretty much all the Qualcomm Snapdragon chipsets starting from premium tier all the way to the low tier pretty much actually like you know try to meet this time closure. Let's see like you know how this temperature actually influences this whole timing closure. So normally in a normal operating temperature range like you know 30 to 40 C range, like you know we try to actually categorize or like you know find a combination of voltage and frequencies which will actually meet the timing. But this same voltage and frequency combinations may not be able to meet the timing at really low temperatures when I'm talking about really low temperatures, this is less than 0 C. So in order to solve the problem like you know probably we can just like you know increase the voltage for this particular frequency throughout the operating temperature range but this is not a power efficient solution you will know. So in order to solve this we just like you know split the whole operating temperature range into two. One is a normal operating temperature range which is above 0 degree Celsius that we can actually still have a lowered voltage for this particular frequency combination and then the temperature goes below 0 C. That's when we have like you know either we can increase the voltage for this particular frequency or if there are like you know multiple operating levels for in particular IP and if only certain up levels or operating levels are having this issue. We can disable those operating levels in the less than C range. So these are like you know those two solutions we can actually try to do in order to achieve this timing closure at really really low temperatures less than 0 C. In a way if you think about this one, this is entirely opposite to what we are normally using the thermal framework for.  But this is completely opposite to like you know what is being done right now that actually when the temperature goes below this particular or like you know the 0 when we reach the 0 C. We want to like you know try to put an operating voltage floor or like you know operating level floor on a particular cooling device. With this I will actually hand over to Tara. Yeah, so I would like to now take you through the existing frameworks in Linux kernel that can support these hardware requirements. And then I would like to walk you through our proposal on extending how we can extend these frameworks to meet these requirements and the probably and talk a bit touch up touch a bit upon the status of these of this work. Okay, so Linux kernel already has a thermal management framework that allows you to monitor temperature and monitor temperature and as well as initiate any mitigating action. The only caveat here is that the entire framework is built around mitigating rising temperature, which means the framework is coded in such a manner that by default it checks if the temperature is rising above a stated threshold. And in case it rises above the threshold mitigating action is triggered. Whereas on the other hand for what Ram just the scenario that Ram just explained, where we should not let S O C's drop below a certain temperature. What we need from the Linux thermal management framework is that the framework should also handle falling temperature, which means that if the temperature falls below a stated threshold, the framework should trigger a mitigating action. And in this case, the mitigating action should be a warming action with another cooling action in like it is in case of rising temperature. So the two points what we the two points what we will touch upon in our proposal is the other framework to handle falling temperature and for the framework to support warming devices just like it supports cooling devices. Moving on to the next slide so before we go into the proposal I would like to walk you through some of the fundamental pieces of the thermal management framework. So the Linux thermal management framework itself is built on this concept of thermal zone, which is a software concept it's nothing but an area or device in S O C that has some kind of thermal constraint. And S O C can have multiple thermal zones and the thermal core can be considered as the manager or driver that manages the temperature requirements of these thermal zones. And then there are the sensor devices, which are devices with temperature sensing capabilities and then there is the associated drivers with the sensors and these drivers provide the thermal the temperature data to the thermal management framework. Moving on, there is this concept of trip points in Linux kernel. So the trip point is nothing but it's a point in the temperature domain, or it's a threshold point upon crossing which the software is supposed to initiate a mitigating action. So the point itself doesn't state any mitigation action or it mitigating action or it does not. It doesn't specify anything. It is just a point in the temperature domain. It's just a threshold point. Now associated with each of these trip points, there will be cooling devices with actually any which actually controls the mitigating action. So they are the devices they provide control and power dissipation they can be actual hardware devices like fan or they can also be software initiated cooling actions. And the cooling devices you typically also have a range of cooling states associated with it. So in the kernel lower the cooling state of a cooling device lower the state of a cooling device lesser as the lower is the mitigating action and as it as the cooling state increases the effect of the mitigating action also increases and to tie all this together. There is this concept of thermal governor, which is nothing but the algorithm that manages the temperature basically the algorithm which decides on how to monitor the temperature the frequency with which to monitor the temperature and finally what mitigating action to take at which point. So a thermal zone usually is a combination of all this thermal zone consists of the sensor that gives it with the temperature data, it will have a set of trip points associated with it and each trip point will have a set of cooling devices associated with it, which can be triggered by the governor to initiate a mitigating action. If the temperature goes above the threshold or the trip point. So what we need to support this particular hardware requirement that the SOC should not fall below a certain temperature is that the instead of monitoring for falling or instead of monitoring for rising temperature the framework should monitor for cooling for falling temperature. So moving on to the next slide. Okay, so now we go through the specific parts of this framework the thermal management framework that needs extension to support this. So the first part is the trip point. So in the existing framework today. We support hot trip points so like I explained trip point is a point in the temperature domain upon crossing with the system will take a cooling action today that I'm the various kinds of trip points in the kernel today. There is active trip point and passive trip point so that is nothing that active trip point would mean that the cooling device that is called is active cooling device and the passive trip point means the cooling device that is called as a that that initiates the mitigating action is a passive cooling device and then there is a hot trip point which means that the system is an emergency and there is the critical trip point which tells you that the system is unreliable. So what we are proposing as an extension to this is adding a cold trip point. So what it would mean is that cold trip point would be a point in the temperature domain upon crossing which the system should undertake a warming action, not a cooling action, but a warming action. So there are multiple ways to handle this. We think the best way to handle this would probably possibly to introduce a new trip point type called cold trip point. The other way would be to not introduce the new trip point type, but to add a new property to the existing trip to the existing trip point structure, which would say whether a trip point should be monitored up or down, which means a trip point should be monitored when it crosses up, when the temperature rises above the trip point or when the temperature goes below the trip point. But we think that this is other than that the best way to handle this is probably to introduce a new trip point type called a cold trip point. As far as the status of this work is concerned, nothing much is done. There are a few prototypes, but we have not posted out any code assets for now. Moving on. Okay. So then the next part of the terminal framework that would need extension is the part of cooling devices and drivers. So in today's existing framework, we have two kinds of cooling devices and drivers. So one is active cooling devices, which are actual physical devices like fan, sort of GPIO line and all that. And then there are software based cooling mechanisms like CPU fret cooling where you say that if the temperature is rising, CPU cannot operate at certain high frequencies or high operating points. And also idle injection. So for the Calcom, Snapdragon, SOCs that we have been working on, the kind of warming mitigation that we need if the temperature is going really low, we would want to stop that from happening. So the kind of warming actions that we have seen so far, one is software based warming mechanisms. So that would be something like a generic power domain based warming where you will say that certain power domains have to be turned on. It has to be kept on or have to be kept at a particular state in order to maintain the system at a particular temperature or to stop the system from dipping down. The other thing that we have seen, another feature that we require is to disable certain devices from going into lower voltage levels. Like for example, CPUs and GPUs, we would restrict the minimum operating point of these devices. We would say that devices cannot operate below a certain voltage level. So these are some of the software based warming mechanisms that we have seen. Other than that, there are also resource specific warming mechanisms, which would mean just turning on or off of a resource, which is sometimes not even controlled by the, which doesn't reside inside the SOC. Maybe it's an outside resource, but turn it on in order to maintain the SOC at a particular level. As far as status of this work is concerned, on the Colcom SSEs, we have already upstreamed a portion of Colcom AOSS based always on subsystem based warming devices. They are just resources that needs to be turned on. So those have been upstreamed. We are in probe. So there is a patch and code which has been posted out for generic power domain based warming device driver, which would mean that if a power domain can act as a warming device or can be used as a warming device, it would just need to register with this particular framework. And it will fit into the thermal framework. So those patches are already out there, which they are being reviewed. And then there is this big piece which would prevent, which would disallow the devices from operating at lower voltages, on which the work is still not started. And then once we talk about all this, I think we should also talk about the term cooling in thermal framework because the, like I said before, the entire framework is based on the premise of monitoring rising temperature and hence the mitigating action is cooling. Whereas now that we have this particular need where we also need to monitor falling temperature and the mitigating actions no longer cooling, the mitigating action can also be warming. So maybe the words like cooling devices and cooling maps and all that needs to be revisited. Those terms probably need to be revisited to see if it makes sense and if we can reword them into something probably better. Okay. Sorry. Okay. And then the other piece in this framework that would need extension, which is a big piece would be the thermal governor itself. So the existing framework supports various governors, stepwise, IPA, bang bang, they're all different algorithms on how they'd all differ on how they monitor and how they initiate the mitigating action. But across the theme across all the existing governors is to like I said is for monitoring rising temperature. So if the temperature goes above a threshold trigger or mitigating action. It could be in Trump base, it could be polling base and the frequency of polling and frequency of monitoring differs across these governors. The way the mitigating actions are triggered differs but it just monitors for temperature going above a certain threshold. Whereas the extension that we would like to see in the thermal governor is support for monitoring and mitigating falling temperature, which is, which would mean that the governor should monitor if a temperature, whether the temperature is falling below the stated threshold or the stated cold trip point. And if it is, it should trigger the warming action as specified. So it could be a separate governor. It may not be any of these governor governors that I mentioned that and that already exists in the kernel. It could be a separate governor, but our proposal here is to extend stepwise to do this because we think that stepwise is governor is fairly straightforward and can handle this. Our initial proposal is to extend the stepwise governor to handle this. So as far as status of this work goes, then some patches, I don't know how we missed the link here, but then some patches have been posted out for this a few months ago, but then nothing much has been done about it. So it is still in a not yet started state, but there was a RFC proposal a few months ago on this. So yeah, I think we missed the conclusion slide. So in a nutshell, what we are trying to tell here is that there is this requirement, there is this hardware requirement that the circuits and the SOC can face issues with timing closure in extreme cold temperatures. And we think that the Linux kernel already has frameworks that can support this and mitigate this particular constraint. We just think that the thermal management framework needs some extension to handle it. And that is I think this was a short presentation. So that is that is it from us. Thank you very much for tuning in and also we will be happy to take questions. We are there on Slack channel we can chat there and we will also be interested in knowing if anyone else is facing such having such requirements and is there anything that we did not cover that you would like to see. For this particular requirement to be extended in the thermal management framework. So I see a question from Anup. Have you guys tested the performance drop? It says that have you tested the performance drop when the system is in warming mode, because the performance goes down on the warm spectrum. I am not sure what do you mean by performance goes down on the warm spectrum. But no, we have not tested the performance drop. We have not done any performance testing with this per se. That is the question. Hey Jess, can I get a table here? Another question which says, will the slides be available online? I would say yes to that. I want to say yes to that, but you would want to consult with the ELC team for that. Okay, what else? Okay, there is a question which says how do you plan to handle power consumption during a case when you are trying to increase heat? So I would say that this is a situation when you are in real, so the situation we are talking about is that we want leakage here. We want static leakage here. We want the system to heat up. We are not really concerned about power managed power savings here. We are concerned about spending some power so as to keep the system running and keep the system alive. So I think that unless Ram you want to add something more here. Yeah, so we just wanted to distinguish between what we are trying to do here actually. So this is not something to enhance the performance or anything of that sort. This is more about the reliability of the operating device. So at that point actually restricting those lower level operating points, it's all about making sure the hardware is reliable and at that point we are not concerned about the power usage. The power consumption or the power savings can actually be in the normal operating range, but when you go to the lower operating range, at that point it's all about the reliability. So that comes in, that takes the frenzy when compared to the power. So there is this question, is there a risk of overcompensation when you keep oscillating? Is there a risk of overcompensation? I'm sorry. Good, good. Where you keep oscillating between cold and hot thermal zones. I'm not sure if you have seen this, but we are also, there is also some kind of hysteresis loop which we plan to put around, which we have around the cold temperature, the monitoring of temperature so that we don't see the ping-pong effect that I think you are mentioning here per se. And also just to add to that, if you are referring the cold and hot as the cold trip points versus the hot trip points, on an actual system, if you think about it, the temperature ranges will be really, really high because the hot tip, hot, you know, these trip points might actually have thresholds in the range of, like say, anywhere about 90 C or something. But this cold trip point would actually have a temperature in the range of less than 5 C, 10 C. So you won't really see a ping-pong between this cold and hot trip points, but moving in and out of this cold trip points, like Tara mentioned, we will actually have a hysteresis in mode so that we make sure we don't really relax the mitigation till we actually clear the hysteresis temperature. So there won't be a ping-pong effect in general. So there is this question from Kyle. For most systems I have worked on, the minimum operating temperature has been determined by non-processor components. Is this work intended for, intended use for all specialty systems with dedicated warming mechanisms? So there is no dedicated warming mechanism as such, like, you know, there is no external warming mechanisms that we are talking about. All we are talking about is just the operating voltage of all the digital rails that a particular SOC is using. So when this cold temperature reaches, the proposal is to just increase the operating voltage of all the digital rails. That's all we are trying to do. There is no external warming mechanism that's involved in here. So there is this other question, like, if the power consumption increases due to warming, how long does it take before battery-level estimation adjusts? I'm not sure about this actually. I don't know how soon the algorithm can actually react to this. Probably I can get back to this on this one actually. I don't really know the answer right away. So there is no other questions probably we can actually end the presentation at this point actually. Thanks everyone. Thanks for joining us.


Just to start off, because I think to look at the implications for Ireland, which is what we're doing here today It's also necessary to look at you know Why did the UK finally decide to resolve its difficulties with the European Union by deciding to leave? And I think if you go back an important point is that the UK always had a preference for a free trade area and a free trade Relationship rather than the single market the customs union does common policies on trade some harmonization of economic and social policies common policies on the environment and this was in order to retain more sovereignty because you've You pull less sovereignty in a free trade area than you do in the customs unions Also due to the Commonwealth issue at the time But that was the first veto that the Gaul exercise was actually in 1958 in November 1958 when he refused that free trade relationship To the United Kingdom and they eventually had to decide to join Margaret Thatcher then in her bruised speech in 1988 when she set herself apart on the social dimension of Europe lit the torch for your skepticism Cameron called the reason the referendum for internal reasons to outflank UK But I also think it's important to note that William Hague sent at October 2011 Before Cameron made that decision that when the opportunity arose the UK would take that opportunity To reset its relationship with Europe that hankering for the free trade relationship They thought the Eastern European states might be willing to go down that road that hankering for that free trade relationship was always there Coincidentally in 1988 also the law persuaded the labor movement at the TUC to back social Europe And that that was in their best interest But in my experience in meeting British trade unionists around Europe over many many years I don't think it was ever a full-blooded conversion on the part of the labor movement Calling a referendum then where he set out a call for fundamental reform of the European Union Adding immigration later, which is what he did because of UKIP getting only let's face it modest concessions in the negotiation It just created in my view a perfect storm in 1975 when Wilson held the referendum the economy was all that was about The UK was the sick man in Europe Now UK has virtually full employment. The eurozone is where the problems are the eurozone is weaker So it allowed immigration to take center stage having said that the leave campaign in my view Extraordinarily got away with telling voters. They could get a good deal simply because the UK has a trade deficit with the European Union Now to look at border controls both customs and passport which Thomas asked me to do It is related to what type of trade agreement the UK is going to be able to negotiate With the European Union from Ireland's point of view We would want them to have full access to the single market more than Norway and Switzerland because Norway and Switzerland do not have access for agriculture and fisheries From Ireland's perspective, that's one of our key interests. So we would want them to have full access But the difficulty is one of the key reasons the UK voted to leave was due to immigration We this has clear from the polls are from the decision last night And if you're part of the single market you've got to accept Immigration but let's say they did decide to be part of the single market even temporarily while they were Negotiating their other free trade agreements with third countries. Would they want to include agriculture? I think we could persuade the European Union to include agriculture in a single market Negotiations, but would the UK agree to that? They may in the short term because if they didn't it would have to impose the EU would have tariffs imposed on agriculture exports from the UK into the EU The UK would have to impose similar tariffs that would increase food prices in the short term But if they didn't impose corresponding tariffs that also have to give them to every third country on a WTO most favorite nation status So it's possible in the short term Agreement on free trade but in the longer term as Britain can negotiate and the one thing about being outside the EU But in the single market as you can negotiate trade deals with third countries in the longer term Britain may revert to a cheap food policy by Negotiating free trade with Mercasor and that has implications then in terms of Brazilian beef being able to access the The Irish market through the UK Backdoor my own assessment is that I can't see the European Union even though it will be in our interest To give the UK a good free trade deal without accepting all the rules We might want it from our point of view and that's one of the jobs We have to do in the national interest But the other member states are going to see that putting their own economies at a competitive disadvantage by giving the UK full access Without the UK having to follow all the rules So I think it unlikely So in that scenario we might have to think in terms of special transitional measures while we adjust to the fact that we've got to Find new markets in the wider Single market now whatever happens if the UK leaves the European Union Which has decided to do but stays in the single market you still have customs procedures because it can negotiate Trade agreements with third countries So you need rules of origin procedures to ensure that those third countries that the UK is Negotiating with can't bypass the common external tariff that the EU has so that's where rule of origin procedures arise You then have customs posts and customs procedures on the land border between Northern Ireland and Republic of Ireland that is Unavoidable there will be customs posts and customs procedures how intrusive and extensive we don't know It will depend on the amount of revenue risk first of all that is payable as as Third country sorry as the UK even within the single market exporting into The European Union that is payable at the point of entry Tariff would be payable for those areas that it doesn't have free trade in perhaps Agriculture but the rules of ours and procedure are the main Important thing in terms of customs procedures if the UK has a deal with Mercasor the Irish Farmers Association Will insist that customs controls are very stringent to ensure that Brazilian beef does not access the Republic of Ireland market bypassing the common external tariff Which are it's up to 70% would be 36% with with dairy so customs controls are an inevitable consequence passport controls Depend on whether you have free movement or not if the UK does stay in the single market and you have free movement Well passport controls don't arise. They will arise if the UK Leaves the single market Doesn't have agreement in relation to free movement So we may still retain free movement rights between Ireland and the UK. There's no reason why that should stop But the UK will not give free movement rights to Polish Latvian Eastern Europeans and the only way to ensure that they cannot get into the UK By using Ireland at the back door is by having passport controls to monitor and check that situation Where will the passport controls be? Well, we have a precedent the last time that the UK introduced passport controls When France fell in May 1940 They put passport controls not on the land border but between Belfast and Liverpool and Belfast and what's now Karen Ryan or if you were flying to London that didn't put them on the land border because they took the view that you couldn't police the land border effectively Cameron has already indicated that that would be the solution Preferred on this time round. I did a delayed the bait last night and Jeffrey Donalds Donaldson Was on and I spoke to him about this and he was quite Candidate if they had to have passport controls so be it it was more important from the Union's point of view to be out of the European Union and be able to do their own free trade deals and have to have that passport controls between Belfast and Liverpool Well, that wasn't a big concern. I suspect it might be if when it actually happens But that was the attitude he took last night so just finally just to end up on One small final point because I think the UK is an exceptional situation And I don't think it necessarily follows that it's going to lead to a rise of your skepticism all over Europe Having said that we know there is an issue. We know there's a problem. We know citizens have lost some faith in the European Project, I was in at a meeting of the European Social Fund last week under the Dutch presidency and the Commission made a very important presentation on a pillar of social rights. I gave the trade the trade union response to the Commission's presentation And it's linked to the next phase of economic and monetary union deepening for a deeper and fair Economic and monetary union. It's important to have a pillar of social rights. My own experience is it's always been social progress going in tandem with economic progress like in the single market and I think it does a danger now with the UK having left that the EU will pause and Be afraid to go further in terms of further integration, but I actually think that will be the wrong response I think the social pillar is a very very important Agenda in terms of persuading citizens to have a restored fate in the European Union. I'm quite confident that if the Commission and the member states go down that road That you know fate in Europe can be restored and I think it's necessary To set the British decision now Aside both Pat Cox will know more than I do about this whether that's actually going to happen or not We'll have to wait and see. Thank you very much


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