Questions and answers. May 2015

Why the commander of the crashed in the Alps A320 could not break the cab door?

When you are in a passenger plane, the door to the pilot's cabin does not make the impression of an impregnable obstacle. But this is a misleading impression. After the attacks of September 11, 2001, the US Federal Aviation Administration released new standards for the design of the door, which (design) would prevent unauthorized entry to the control tools of the aircraft. Soon, these standards were distributed around the world. First, the door must be locked so that if it is closed from the inside, then it is impossible to open it from the outside. A person inside must give permission to enter by pressing a button on a special panel at the door. Secondly, its design should be so strong as to withstand small arms shots and even impacts of grenade fragments. For this, the door is reinforced with Kevlar, which is used in body armor. It is impossible to handle such a door with a hatchet. And just recently it became clear that an attempt to defend oneself from one disaster led to another.

What is a “blind spot” in the eye?

[RICH_HTML type = imageset] [/ RICH_HTML] This is the area on the retina of the eye where there are no photosensitive cells. The optic nerve is attached to this place. If the cones and rods were located on the outside of the retina, there would be no need for a blind spot. But the eye evolutionarily developed so that the photosensitive cells “look” inward and there is no place for them in the place of attachment of the nerve.

Are materials harder than diamond?

In a practical sense, perhaps, a diamond cannot be replaced with anything, however, scientific research conducted in 2009 showed that lonsdaleite, one of the allotropic modifications of carbon, is one and a half times harder than diamond. The structure of the Lonsdaleite crystal lattice resembles a diamond lattice, but there are also differences in the number of atoms in the unit cell. Lonsdaleit is unusually expensive to obtain and is unlikely to find wide application in industry.

Is it true that there are marsupials without a bag?

Yes, in Australia there lives an animal that belongs to marsupials, but does not have a bag. This is a nambat, or marsupial anteater. Due to the lack of a bag, the born cubs simply hang on their nipples, clinging to their mother’s fur. So the female nambata and drags them for four months, after which the children can enter an independent life.

Is there a natural limit to the mass of a star?

There is no scientifically substantiated limit. Attempts to calculate it theoretically were based on the concept of the so-called critical Eddington luminosity - that is, the maximum luminosity of a stable star, determined by the condition of equilibrium of gravitational forces and the radiation of the object directed in the opposite direction of pressure. In the 1990s and 2000s, a group of astronomers from a Baltimore-based Institute for Processing Data from a Space Telescope conducted a study of the Arca cluster, a supermassive cluster located near (just 100 light-years) from the center of the Galaxy. It was expected that there could be very massive stars, but it turned out that the limit is 130 solar masses. This was consistent with earlier theoretical calculations. Then it was decided to consider the natural limit of 150 solar masses. This rule generally works, but it knows the exceptions. For example, the mass of the star R136a1 in the Large Magellanic Cloud is estimated at 265 solar masses.

Figures : 1, 000, 000 carbon atoms stretched into a chain will make up the thickness of a human hair. 2.4 billion km is the diameter of the largest (in radius) of the famous stars - UY Shield.

You can ask a question at the following address: 127018, Russia, Moscow, ? Polkova St., 3, bld. 1. e-mail:

The article “Questions and Answers” ​​was published in the journal Popular Mechanics (No. 5, May 2015).

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