Tuesday, 29 December 2009

Islamic theories of inertia

Several Muslim scientists from the medieval Islamic world wrote Arabic treatises on theories of motion. In the early 11th century, the Islamic scientist Ibn al-Haytham (Arabic: ابن الهيثم) (Latinized as Alhacen) hypothesized that an object will move perpetually unless a force causes it to stop or change direction. Alhacen's model of motion thus bears resemblance to the law of inertia (now known as Newton's first law of motion) later stated by Galileo Galilei in the 16th century.
Abū Rayhān al-Bīrūnī (973-1048) was the first physicist to realize that acceleration is connected with non-uniform motion. The first scientist to reject Aristotle's idea that a constant force produces uniform motion was the Arabic Muslim physicist and philosopher Hibat Allah Abu'l-Barakat al-Baghdaadi in the early 12th century. He was the first to argue that a force applied continuously produces acceleration, which is considered "the fundamental law of classical mechanics", and vaguely foreshadows Newton's second law of motion.
In the early 16th century, al-Birjandi, in his analysis on the Earth's rotation, developed a hypothesis similar to Galileo's notion of "circular inertia", which he described in the following observational test:
"The small or large rock will fall to the Earth along the path of a line that is perpendicular to the plane (sath) of the horizon; this is witnessed by experience (tajriba). And this perpendicular is away from the tangent point of the Earth’s sphere and the plane of the perceived (hissi) horizon. This point moves with the motion of the Earth and thus there will be no difference in place of fall of the two rocks."

* Abdus Salam (1984), "Islam and Science". In C. H. Lai (1987), Ideals and Realities: Selected Essays of Abdus Salam, 2nd ed., World Scientific, Singapore, p. 179-213.
* Fernando Espinoza (2005). "An analysis of the historical development of ideas about motion and its implications for teaching", Physics Education 40 (2), p. 141.
* Aydin Sayili (1987), "Ibn Sīnā and Buridan on the Motion of the Projectile", Annals of the New York Academy of Sciences 500 (1), p. 477–482
* O'Connor, John J.; Robertson, Edmund F., "Al-Biruni", MacTutor History of Mathematics archive.
* Pines, Shlomo (1970). "Abu'l-Barakāt al-Baghdādī , Hibat Allah". Dictionary of Scientific Biography. 1. New York: Charles Scribner's Sons. pp. 26–28. ISBN 0684101149.

Wednesday, 23 December 2009

Fibonacci numbers

Fibonacci number is a sequence where each remaining number is the sum of the previous two.

Monday, 7 December 2009

Vitamin or Antibiotic. Which one?

Our body has a defensive mechanism - immune system. What's that?
Immunity is a biological term that describes a state of having sufficient biological defences to avoid infection, disease, or other unwanted biological invasion.

It's a feedback of our organism for some un-usual conditions, like cold or hot weather, finger cut, virus, and so on.
Vitamins increase the power of our immune system, antibiotics - decrease.

Let's imagine that immune system is an ambulance of our organism: little cars, which go to the hotspot, problem zone.
First case, virus damage one of our cells, in the result, it doesn't do its usual tasks. In this case, our "ambulances" come to solve the problem. And when our immune system is not able to fix the problem, it needs more power. That is a vitamin.
Second case, virus damage only surface of the cell, it continues its usual tasks, but our immune system cannot respond that cell. Immune system "thinks" that this is some kind of virus. And try to "kill" it. In this case we need something to calm down our immune system, because it is trying to kill an important cell in our body. It's an antibiotic.

Of course don't use them without doctors receipt.

Thursday, 3 December 2009

Virus is going to a Coke factory and having them make Pepsi

The viruses are amazing… They go into a cell… It's barely a life form on its own. But when it goes into a cell, it completely takes over the machinery and turns it to its own uses. And it's a hostile takeover. «Your cell, under new management»… It would be like going to a Coke factory and having them make Pepsi.

And if you think about this kind of stuff too hard, here's the kind of joke you come up with.

A virus walks into a bar. The bartender says: «We don't serve viruses in this bar». The virus replaces the bartender and says: «Now we do».

An infectious disease walks into a bar. The bartender says: «We don't serve infectious diseases in this bar». The infectious disease says: «Well, you are not a very good host».

A few bacteria walk into a bar. The bartender says: «We don't serve bacteria in this bar». The bacteria say: «But we work here, we're staff!»

A room-temperature superconductor walks into a bar. The bartender says: «We don't serve any superconductors in this bar». The room-temperature superconductor leaves without putting up any resistance.

An infrared photon walks into a bar and says: «Is it hot in here, or is it just me?»

A neutrino walks into a bar. The bartender says: «We don't serve neutrinos in this bar». The neutrino says: «Hey, I was just passing through».