The Star of Bethlehem

I must confess that I am very interested in news that have to do with the cosmos, its origin in the Big Bang, its immensity, whether it is flat or curved, quasars, neutrinos and black holes, the still unsolved problem of dark matter, whether it will extend indefinitely or end up contracting again on itself in a Big Crunch... I suppose that this curiosity is influenced both by the bewilderment before its enigmatic immensity and the fascination before the beauty of a starry night, and by the desire that every human being has felt since the beginning of time to try to decipher the mystery of existence, where we come from and where we are going, even though we already know that we are made of star dust and that one day we will be again, even though ours is dust in love as Don Francisco de Quevedo wanted. 

This comes from that astral conjunction that will make two planets as far apart as Jupiter and Saturn align from our point of view, and that this alienation will be visible to the naked eye in the spectacular increase in luminosity of the whole that we will perceive from here as the same flash. The phenomenon was not repeated since 1623, when Spain was the most powerful country in the world (there were still 20 years left before the spanish Tercios suffered their first defeat at Rocroi), the dynastic union with Portugal extended our Empire through Africa, Asia and the most exotic islands in the Pacific Ocean, and Felipe III gave way to Felipe IV. Only some sharp spirits like the already mentioned Quevedo saw the inevitable decline of those who tried to embrace more than they could. It is the same decadence that Joseph Roth describes in 'The Radetzki March' referring to Francis Joseph's Empire, and that is now announced by Paul Kennedy in 'The rise and fall of the American Empire' while the stars remain seemingly unperturbed in their violent inner hells.

It seems that the same astral alignment took place in the year 7 before Christ, giving rise to the beautiful legend of the Three Wise Men who, following their light, would have come from the East to the cave of Bethlehem, where Jesus of Nazareth was born, bringing him symbolic presents of gold, incense and myrrh, fit to his divinity. That the planetary conjunction took place seven years before the commonly accepted date poses the recurring problem of whether we are accurately measuring the actual date of Jesus' birth, which, according to Jupiter, Saturn, and the Three Wise Men could have been born seven years earlier than history attributes to him. In any case, the phenomenon will take many years to repeat itself. We are less than specks of dust in the middle of the cosmic immensity, and the astral conjunction that inspires these lines gives us an excellent excuse to reflect on it. 

The visible universe has a known diameter of 90,000 million light-years and is still expanding faster than we thought. As far as we know, it contains about 100 billion galaxies, each of which has between 100 billion and a trillion stars, giving us the unimaginable figure for our minds of 10 to 24 stars (24 zeros behind 10). If only 5% of these stars were similar to the sun, that gives us 500 trillion suns like ours, and if only a fifth of them have a habitable planet revolving around them, a very conservative calculation, there would be one hundred trillion (millions of billions) of theoretically habitable planets for being in a strip where it is neither too hot nor too cold. If intelligent life were to develop at 1 per cent there could be as many as 10 billion intelligent civilizations in the observable universe, because it cannot be ruled out that there are other universes that we do not know about. These are numbers that would be multiplied even more if we were to consider other forms of life not based on carbon, although we will never know because the distances are so enormous that it would take billions of our years to reach those planets. We seem doomed to not know.

So we have no choice but to forget the universe and apply those calculations to our galaxy. The Milky Way has about 100,000 million stars, 20,000 million of which resemble our sun, and if 20% of them have habitable planets we would have in the vicinity 4,000 million planets similar to ours and even 100,000 intelligent civilizations... and even much more developed if we consider that many of these planets are several billion years older than Earth, which would have given them more than enough time to give birth to civilizations more sophisticated than ours. 

But, although there must be a lot of alien life, we are not able to find it despite the efforts of scientists around the world who are looking for it with programs like SETI. This is what is known as "the Fermi Paradox". Apart from the sidereal distances separating us, another possibility to explain our apparent loneliness is that life has a hard time emerging and developing, as shown by the fact that it took 700 million years to appear on Earth. Although perhaps it is better that we don't meet those aliens because as Stephen Hawking sarcastically said they might be hungry... 

Jorge Dezcallar Ambassador of Spain