Thirteen months in one year?

After talking about days and hours, this is the turn of the month. Like the day, it corresponds to a natural cycle: the revolution of the moon around the Earth. As we know, seen from the Earth, the moon does not seem to rotate around its axis and always shows us the same face. However, if we take as a reference point a star or the sun, a rotation can be seen. An observer located on the sun would see successively all the points on the surface of the moon, therefore would see it rotating around itself. It could also be observed that its period of rotation is the same as its revolution around the Earth. This is why it always shows the same face towards our planet.

The 24th hour

Melting Clock
Sculpture by Dalí

I have tweaked the title of the well-known novel by the Romanian writer Constantin Virgil Gheorghiu (The 25th hour), because in this post I am going to talk about the hours. As with the days, which we talked about in the previous post, there are different types of hours.

Each type of time is defined by dividing the length of the corresponding day by 24. Thus there are as many types of hours as there are days: lunar hour, sidereal hour and mean solar hour. But in addition to these three, there are two more: the true solar time and the official time (see the attached table). The first is a consequence of the fact that the true solar day differs from the mean solar day by up to a quarter of an hour, approximately. For that reason, when ship captains wanted to calculate the geographical longitude of their position by observing the moment when the sun passed through the meridian, they had to apply correction tables based on the date. If we divide the length of each true solar day by 24, we will get the true solar hour, which of course is equal to 60 minutes just a few times a year.

Works and Days

I have taken the title of this post from Hesiod's book. Although I won’t talk about works here, I will talk about days. The word day has two different meanings: the whole day (24 hours) and the part of the day when there is sunlight. Thus, it could be said that

day = day + night

which seems absurd, for a mathematician could deduce that the night does not exist. Instead of that equation, and to make it clear that there are two kinds of days, we should use this expression:

day₁ = day₂ + night

Here, day₁ is a natural cycle, the period of the Earth's rotational motion around its axis. But then a problem arises: when can we say that the Earth has made one complete rotation around its axis? The problem is, to define the period of a moving object, it is necessary to have a reference point. The results will be different depending on which point is chosen.

My 10 Favorite Scientific Discoveries of the 20th Century

In a post published two weeks ago, I commented on an article in Science News that tried to answer this question: which were the ten most important scientific discoveries of the last century? Some of my readers asked what is my personal opinion. This is my answer.

To begin with, I will point out that scientific research can advance in four different ways:

1. Theoretical science, which tries to discover fundamental laws in the universe.
2. Experimental science, which confirms or falsifies theories by carrying out experiments.
3. Observational science, which instead of experimenting, observes. Astronomy, for instance, uses these methods, as experimentation is almost never possible.
4. Technology, the practical application of science, whose goal is to build devices that work.

Will we be able to build conscious beings?

I use the term conscious beings, because the term conscious machines has materialistic connotations that I do not share, while artificial intelligence has been burned and abused by generalist media.

Before trying to answer this question, I want to make a few previous clarifications:

1. We are now capable of building conscious beings: our children. Four billion years of evolution have led to the appearance of a type of beings (us) endowed with self-awareness and capable of reproducing. This was a natural process, which we have not designed ourselves, but has been given to us since before we existed. However, when someone poses the question in the title of this post, it is usually interpreted thus: will we be able to build artificial conscious beings, by means other than natural, devised and developed exclusively by ourselves?