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Letter from the editor | 86

On fire, shadows, cold and lights

The title above seems like an allusion to the war that is now under way. Times of war are somber, tragic, painful. In particular, those that seem to cause a retreat of centuries in the minimum codes of civilization, built up with difficulty by humanity in the course of its history. Which for this very reason threaten to replace every positively combative, optimistic without being naive attitude, by a bitter pessimism or a deep skepticism, with regard to human potential for building societies of well-being. And they end up by threatening even one’s trust in the responsible use of knowledge to the benefit, and not to the detriment, of human beings. It is, however, indispensable to bet more in a game of shadows and lights, and to maintain the conviction that knowledge can indeed be used in favor of human society, and, very often, it is. The title above, by the way, does not refer to the war, but to new lights, knowledge about Amazonia that, if used well, will be of the greatest importance for dealing with this gigantic area that has weight in the environmental balance of the planet.

The Amazon basin is a source of surprises. And just look here at the latest: forest-clearing fires in the forest, besides all the already known economic and environmental effects that they cause, reduce the temperature of the forest. There is an intriguing touch of paradox in that fire is capable of cooling down anything whatsoever, including an immense forest – but it isn’t. In the cover story of this issue, starting on page 30, special reporter Marcos Pivetta explains in detail the work of a team of researchers that made it possible to estimate a reduction of up to 2° Celsius in the temperature of the forest and a reduction of from 15% to 30% in its normal volume of rainfall at the height of the forest clearing fire season, between August and October.

The key to these phenomena lies in aerosols. These microscopic particles, in this case, arising mainly from the combustion of the vegetation, occur in startling concentrations in the Amazon in the most intense period for burning – with peaks of 30,000 particles per cubic centimeter of air, a level about 100 times higher than is recorded in São Paulo on the most polluted days of winter. Well, by making up dense clouds of smoke, a heavy shadow over the forest, aerosols reduce the intensity of the sunlight that, under normal conditions, would strike the ground, and it is there that they cause a slight cooling down of the forest – amongst several other effects.

Also worth highlighting in this issue is the article of the engagement of several Brazilian groups in a race that has already started at the most advanced frontiers of physics: the race that is chasing after the quantum computer. A project that is still far from materializing, this computer should be capable of carrying out in minutes calculations that today’s fastest supercomputers would take billions of years to do. Eleven groups of physicists spread over the country – reports assistant editor Ricardo Zorzetto, starting on page 54 – are getting some results to show in the direction of this computer, whose capacity for calculating doubles with each atom added to its processor.

In Humanities, I call your attention to the article on research that gives consistent support for the discussions under way on tax reform (page 84). Structured on a solid mathematical basis, the study shows that the differences between states in levying the ICMS (the Portuguese acronym for the Sales and Services Circulation Tax) cause significant losses for the country, in such a way that its simple equalization could reduce losses to the economy of between R$ 4.5 billion and R$ 9 billion a year.

And, to conclude, I would point out a section that until today has not appeared in this space: the review of books. Worthy of attentive reading are the comments by philosopher José Arthur Giannotti on the books A Ditadura Envergonhada (The Bashful Dictatorship) and A Ditadura Escancarada (The Wide Open Dictatorship), by journalist Elio Gaspari. Giannotti puts back again into an experience that is very close to us the time of violence and heavy shadows that we have, fortunately, left behind, but which still produces a lump in the throat and choking.