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So, in all those ways it is already a clean source of energy, we just need to know how to tap it. And you can imagine the level of comfort we have, here it’s not even you know even if all the I mean if all of the worlds start living this fanciful lifestyle, maybe we will go up by a factor of 10 or 20 in our energy usage or maybe even 30. Even if we do that, we have you know; I mean we have a factor of 365 into 24 that is the number of you knows hours that are there in a year right. So, we are looking at something like 7000 and 8000 hours that are there more than 8000 hours in fact, in a year. So, if you look at more than 8000 plus hours in a year, that is the margin of error we have. Every hour we are going to get enough energy for the entire humanity for the year, and you have 8000 plus hours to deliver that energy. So, that much amount of energy. So, even if you put 10 per cent error, 100 per cent error you double the amount of energy you said, you triple the amount of energy, you go up by a factor of 20, go up by a factor of 30 in the energy usage, you still have way more energy arriving at earth than we are possibly using right. So, that is a beautiful piece of information for us to have to understand and latch on to so, that we can you know to build on it. So, this is the point that I wanted to emphasize in the calculation today, that we receive as much energy every hour as we require for the entire year. But that’s not all, there are some more interesting ideas given that this context is there and that’s what I will touch upon briefly in the next slide. What I am going to show you in the next slide is a bit futuristic, but it is it’s more from physicists have thought of imaginary situations, where we can do even better than this and that is all that I am trying to point out. (Refer Slide Time: 34:05) So, you can see here in the 1960s there was a physicist an English man who lived in the US his name was Freeman Dyson. So, he suggested that you know if it were possible to construct a sphere the size of the earth’s orbit, then you can capture all the energy that is coming towards the earth’s orbit. So, whatever energy, so right now we only capture the energy that is coming here right, we only capture the energy that is coming to the earth, but what about all this energy that is going away we are not able to capture it right. So, if we had a hypothetical I mean we managed to if our technology advanced far enough, that we could make a sphere. Some thin thin material sphere which is the size of earth’s orbit, then you can capture all the energy that is coming from the sun. As opposed to only what is coming in this cross-section, all the energy that is coming from the sun can be captured, but this is only a theoretical concept because as of now at least. Because nobody knows how to construct such a sphere, I mean we are no struggling to make we just about making buildings, which are you know say a 100 floors, 150 floors tall and so on. And those are our major accomplishments as of today, and many countries try to no out of prestige issues they will try to build very tall buildings. So, that’s really how far we have come; to build something in earth’s orbit that extends the size of the earth’s orbit, it is itself something that we have not even really imagined in any serious sense, and this may not be the only implementation for it, there may be other implementations where you do only partially this activity to get more energy. But in any case, we have not looked at it, where would we get the material for it, where would we get the material to build such a structure let alone go about building it. We may not have enough material on earth; to build even a thin you know structure which extends the orbit of the earth. But in any case, it is an interesting concept to keep in mind and that’s why it is you know it is the in fact, specifically referred to as the Dyson sphere named after the man Freeman Dyson and you can go look it up you will find in interesting information on this. And incidentally, as an aside as an extension of it, there is something called as the