I have many friends who work on this problem their whole lives. One friend, every time I see him I would say 'how long till we have fusion?' and every time he would tell me 'about 5 years' he would say. My friend he is dead now but the last time I see him I ask him 'how long till we have fusion?' and he respond me 'about 5 years' Now it seems that the consensus in the field is that we are making great progress and it really seems we will have fusion in about 5 years. But I would say to my friends I would say 'why we need it?' Perhaps we could use fusion to boil ocean water and irrigate the Sahara, or some project like this, some great project Like making enough water for the Sahara. It turns out we could not do this since this would heat the atmosphere of the earth. But this I tell them I say 'why we need it?' Every reaction has a size. Take campfire, if you build campfire the size of candle it will blow out. The surface area of the flame is too large and it cools rapidly a puff of wind will blow it out. But if you build campfire big enough, build campfire campfire size then it keeps itself warm and the reaction can be sustained. So every reaction has a characteristic size and the size of fusion reaction is size of sun and we want to make it on scale of campfire. This is like if a virus were to try and build campfire, and the relative ratio is about right. We are to viruses like sun is to us. So we try to make fusion on our scale it is like virus or single cell organism trying to build campfire it is ridiculous and we absolutely don't need it just like the virus does not need it, we absolutely do not need it.
The sentiment at the heart of this is being that we do not need fusion I have sympathy for the perspective for but do not agree with it. Eventually we will need fusion power though for now and for the next few decades at least I think we should instead try to use fission power. But I thought the entire episode was very interesting partly because of the perspective from which it is given. Also I think the picture evoked by the analogy of a virus trying to build a campfire is really impressive and striking. Where Efros wanted to use it to show that we do not need fusion I think it is just as effective a way of demonstrating the reason that it is so very hard to make fusion work on our scale.