Why can’t a person tickle himself?

Why can’t you tickle yourself?

Selma Vihriälä, 10

Tickling the effect is based on surprise. You can’t tickle yourself, because the brain predicts a person’s own movements very accurately.

When you decide to tickle yourself, the brain sends two messages: the first directs the muscles to the tickling movement, and the second conveys to the sensory system advance information about how the touch will feel.

That foresight removes the surprise and dampens the effect of the tickle. The more accurately the brain predicts the touch, the less it feels surprising and tickling.

The movements and timing of another person’s fingers are unpredictable. In this case, tickling makes you laugh because it activates mixed feelings of surprise and excitement.

Unpredictable touches are interpreted by the brain as important because they are a potential threat, in which case they trigger tension and a mild alarm response in the form of laughter.

In a safe playful situation, tension turns into joy. That’s why tickling makes you squirm and laugh.

It has been observed that in addition to humans, some other social animals, such as monkeys and rats, may tickle each other during play. It helps young animals develop social and emotional skills that are important for being together and creates trust and strengthens relationships.

Researchers believe that over the years, the tendency to tickle and laugh has also evolved in humans because it has promoted interaction and cooperation, which are important in life.

Tuija Aro

assistant professor of clinical psychology

University of Jyväskylä

Can bacteria be seen with the naked eye if they were in a really big group?

Kauko Öhman, 6

Yes Oh. Bacteria are often made to form such large groups in research laboratories that they can be seen with the naked eye.

Such colonies are formed on the surface of the culture medium, i.e. the ideal growth medium for bacteria due to its nutrients and trace elements.

It typically happens that the growth of a single bacterium forms a round colony that can be seen with the naked eye within just one day.

Even outside the laboratories, you can see clusters of bacteria with the naked eye.

If, for example, a slice of potato is stored in a plastic case so that it does not dry out, visible bacterial colonies from bacteria from the air can grow on its surface. If you brush the surface with your fingers, bacteria originating from the skin can also grow to be visible to the naked eye.

Bacterial colonies can look quite different. For example, mandarin-like colonies can appear on a potato, which can be yellow, pink, bluish or black, depending on the type of bacteria in question.

The resolution of the eye is somewhat less than about 0.1 millimeter, or 100 micrometers. The diameter of bacteria is often around 0.001 millimetres.

From this, the volume of a spherical bacterial colony and the volume of an average bacterium can be calculated. It can be calculated that approximately one million bacteria are needed inside a clearly visible colony.

Mikael Skurnik

Emeritus Professor of Bacteriology

How do the stars and galaxies that went into the black hole actually fit there? Isn’t it cramped in there? Could our house and trees go there?

Vilma Tetri, 4

A pocket galaxy There are many black holes in the Milky Way and other galaxies. They are really massive. The weight of the black hole corresponds to at least a few masses of the Sun.

We also know that in the centers of galaxies there is a supermassive black hole, the mass of which can be over a billion times the mass of the Sun. The black hole in the center of the Milky Way weighs about four million Suns.

Galaxies do not go into black holes, but they are part of galaxies. Instead, the star can end up in a black hole. However, it disintegrates before it gets there due to the great gravity caused by the black hole.

We don’t know exactly what happens inside black holes, but their mass is believed to be at an infinitely dense point at the center, called a singularity. A singularity can always fit more mass.

If the black hole was really close, houses and trees could also go there. However, there are no black holes close to Earth.

Black holes also do not absorb everything nearby, but celestial bodies can also orbit a black hole in the same way that planets orbit the Sun, as long as the black hole is not really close.

Atte Keitaanranta

PhD researcher in astrophysics

University of Helsinki

Which has more parts, a person or a building?

Noa Pääkkö, 3

Buildings come in many different sizes and for different uses. However, it can be estimated that an average building, such as a standard detached house, has at most half a million building parts.

In buildings, the smallest construction parts are, for example, screws and nails, which are in the structures of houses, such as roofs, walls and floors.

As a living being, a person must have a huge number of small building parts in order to function. In humans, those building parts are tiny cells that, for example, consist of hundreds of bones and thousands of muscles. A huge number of cells are needed because the structure of a human being is so complex.

The human brain alone can have up to 100 billion neurons. It enables a person to think and live, such as building buildings.

There are clearly more cells in a person than there are construction parts in buildings. On the other hand, there are about 7,500 pieces of bones, muscles and other named parts larger than cells.

On the other hand, everything that exists, such as building parts and cells, is made up of elementary particles. They are the smallest building block of all matter. Since the building is much bigger than a person, there are more elementary particles in the building than in a person!

Mikael Segerstråle

university lecturer of physiology and neuroscience

University of Helsinki

Send the question, the questioner’s full name and age to lasten.tiedeskö[email protected]. The column is provided by Touko Kauppinen.