SEADSTEM

Pure water consists of only two chemical elements. Chemical elements are pure substances that cannot be broken down into other substances. The two elements that make up water are oxygen (chemical symbol: O) and hydrogen (chemical symbol: H). In water, two hydrogen atoms combine with an oxygen atom. This basic building block of water is called a water molecule and has the chemical formula H2O. In addition to these basic building blocks, water can contain many dissolved substances. While the content of dissolved substances in drinking water, for example, is rather low, seawater has a very high content of dissolved salt and therefore tastes salty.

Dr. Volker Rachold is a geochemist and head of the German Arctic Office at the Alfred Wegener Institute for Polar and Marine Research.

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The earth is almost shaped like a sphere. This is due to the force of gravity. It causes all masses to attract each other. The earth was formed when many rocks joined together to form a large planet through gravitational force. Everything is most strongly attracted towards the center of the planet. After its formation, the Earth heated up and the rock became liquid. The gravitational force caused it to flow towards the center of the earth. The corners of a cuboid are further away from the center than the sides and would protrude like mountains. The gravitational force caused the material to flow downhill from each "peak" until the valleys were filled in and every point on the surface was the same distance from the center: a sphere emerged. Nowadays, the earth's crust has cooled and hardened, allowing mountains and valleys to form. The earth's surface therefore deviates slightly from the spherical shape. However, the force of gravity still causes rocks to be transported from the mountains down into the valleys and the earth adapts to its spherical shape.

Dr. Robert Dill works as a geophysicist at the German Research Centre for Geosciences (GFZ) and is involved in modelling the Earth's gravitational field, the Earth's rotation and the water cycle, among other things.

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Humans are creatures of the same temperature. This means that our body has to regulate the body temperature, especially in the head and upper body (body core), to around 37 degrees at all times, no matter how warm or cold it is around us. This is vital, as at 37 degrees core body temperature all functional systems, such as the nervous, endocrine, cardiovascular and muscular systems, can work optimally and we are and remain healthy.

When we exercise and do sport, our skeletal muscles work and heat is generated within the body. To release this excess heat, small droplets of water form on our skin to cool us down. We sweat. If we spend too long in cold water while bathing, for example, our body releases heat into the cold water and starts to cool down. We start to shiver involuntarily - we get cold. When we shiver, our skeletal muscles are also active and produce the heat we now need to keep our core body temperature stable at 37 degrees. In this way, our body works in reverse when the outside temperature is warm or cold, providing cooling through sweating or more heat through shivering.

Dr. Kristin Wick works and researches at the Potsdam University of Applied Sciences for Sport and Management in the field of applied sports science.

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Growing older is normal. Evolution has arranged it that way, as our earth only has a limited amount of space. Imagine if everyone got younger again and lived forever - how many people would there be then?

Our genes influence how old we live. However, they only determine our life expectancy by an estimated 10-15 percent. Our lifestyle and external influences, such as diet, sunlight and chemicals, play a much more important role. These have an effect on our cells and organs and change them. It's like a bicycle, it rusts - so it changes. You can look after it, but you can't completely prevent the wear and tear process. However, you can replace broken parts on a bicycle. Unfortunately, this is not possible with most cells and organs in our body.

So we can't stop or reverse the ageing process. But we can slow it down! You can do this by living a healthy life, i.e. eating healthily, exercising, not smoking and trying to be happy in all phases of your life.

Professor Tilman Grune is Scientific Director at the DIfE and heads the Department of Molecular Toxicology. His laboratory investigates, among other things, age-related damage to proteins in cells and tissues.

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First of all, a galaxy is a structure made up of many millions or billions of stars and their planetary systems. However, the spaces between the stars are not empty, but contain vast clouds of gas and dust. In addition, there are neutron stars and black holes as the remnants of massive stars after they explode as supernovae. In the center of the Milky Way and most large galaxies there are even black holes with millions to billions of times the mass of our sun. However, all this is still not enough to explain the measured masses of galaxies. There must therefore also be large quantities of so-called "dark" matter, which does not emit light and can only be detected indirectly via its gravitational effect. If you could put all the building blocks of galaxies on a scale, dark matter would be the main component, followed by gas, stars, black holes and finally cosmic dust and solid bodies such as planets and their moons.

Lutz Wisotzki is an astrophysicist and professor at the University of Potsdam. His research focuses on spectroscopic studies of galaxies and the circumgalactic medium.

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Scientists have discovered that a substance called dopamine is released in the brain when we listen to music. Dopamine is also called the "happiness hormone", because it acts on the reward system in our brain, which makes us feel good.

With our favorite songs, we also know them well and therefore anticipate certain parts that we like. This creates tension and relaxation when we hear the part. Something similar happens when we eat or when we see something delicious that we are about to eat.

Children and young people have answered the question themselves in this way:

"Favorite songs give you a connection and positive memories."
"Favorite songs influence your feelings."
"There is a perfect song for every situation."
"It's good to hear in lyrics that another person feels the same way you do or has experienced something similar."

Berit Immig works as a music therapist at the Clinic for Child and Adolescent Psychiatry, Psychotherapy and Psychosomatics at the Ernst von Bergmann Clinic.

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For a vaccination, for example against the flu or corona, doctors either use fragments of the virus or, in some cases, the complete virus in an attenuated form. The human immune system recognizes this pathogen and starts an effective immune response: we get a cold, cough or fever. This helps us to fight the pathogen. Various systems and cell types come together in the process. For long-term protection, so-called T and B cells are activated, which recognize the virus components and can transform themselves into memory cells. This gives the immune system the ability to remember this virus even years later and to immediately start a defense reaction in the event of an infection with the same pathogen. As a result, we sometimes do not even notice that we are infected when we are infected again because the immune system can react immediately. In order to effectively build up and maintain this memory, booster vaccinations are necessary and sensible at intervals of several years.

Katja Hanack is Professor of Immune Technology at the University of Potsdam and researches technologies to produce antibodies for disease research and diagnostics.

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When it comes to food, bats have it all! No wonder with over 1,400 bat species. Most of them eat insects, others like fruit or nectar. Bats are very important because they pollinate flowers and spread seeds at night or keep insects that eat our crops at bay. Some bats even hunt birds, fish, frogs or other bats. The three species of bats that really drink blood are true specialists. They are only found in South and Central America. The best known is the "common vampire". It particularly likes to drink the blood of cattle. Once it has discovered a victim, it lands nearby and sneaks up on it. It uses its sharp canine teeth to scratch the skin and lick off the blood. The special saliva ensures that the blood does not dry so quickly. Because it is small, the vampire only needs a little blood and the victim often doesn't even notice. Sometimes people are bitten in their sleep, which can be dangerous if the vampires transmit diseases. Fortunately, however, this is relatively rare.

Dr. Manuel Roeleke is an ecologist at the University of Potsdam. He studies the movement behavior and information exchange of animals.

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Stars have not always existed. They are born and live for millions or even billions of years before they die. There are clouds in the universe that consist mainly of hydrogen, but also of dust. Without dust and gas, stars would not form. Stars are formed from the dense cores that are embedded in such a cloud. Various forces act within it. The most important of these is gravity, whose attractive effect ensures that the nuclei continue to contract. When matter is compressed enough, its density increases and it begins to heat up. This continues in various phases over a fairly long period of time. When the star has become so large and dense that the central region can trigger a nuclear reaction, the star shines and we can see it. Some of the stars we see are quite close to us, like our sun. Others are further away, but bright enough that we can still see them. With telescopes, we can see stars that are even further away or simply fainter.

Dr. Silva Järvinen is interested in the activity and magnetism of different types of stars. She also loves observing with instruments, for example in the USA and Chile.

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The force of gravity is present everywhere in the universe. Every object exerts it: The greater its mass, the greater the gravitational force it exerts on all other objects. However, the force of gravity also depends on the distance to the object and quickly becomes weaker as you move away from it. For example, the force of gravity exerted by the earth is stronger on the earth's surface than further away. Sitting in an airplane, you don't notice much of a difference, where the gravitational pull is still 99.7% compared to the Earth's surface. The ISS space station still experiences 88.8% and the moon only 0.03%. However, this is enough to keep the moon on its orbit around the earth! In addition to gravity, other natural forces act on all objects, e.g. electromagnetism. If an object lies still on the surface of the earth, gravity is in balance with the other forces. However, it can also happen that a celestial body is so massive that there is no such equilibrium: This can result in a black hole.

Dr. Axel Kleinschmidt works in the "Quantum Gravity and Unified Theories" department at the Max Planck Institute for Gravitational Physics in Potsdam, focusing on string theory.

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We use the term temperature to describe the thermal state of a body. But what is cold? Strictly speaking, there is only heat, at least in physics, where heat is theenergy which is transferred between two bodies at different temperatures. If there is an ice cube in your water glass, the warmer water transfers energy to the ice cube, thawing it. Now imagine that your own body is the warm body at about 37°C, while the surroundings are perhaps only 10 °C warm. The heat flow is now from your warmer body to the cold environment - so you are literally losing energy! You can imagine that the sensation of cold, i.e. the feeling when we lose heat, can be unpleasant and even dangerous in different ways for human beings and also for animals. For example, although polar bears have the same body temperature as humans, they can withstand air temperatures as low as -50°C while resting! They are helped by a fat layer and their special fur - we, on the other hand, are left with only hats and gloves...

Dr. Josefine Lenz works in polar research at the Alfred Wegener Institute in Potsdam. Working on frozen lakes in the Arctic, she has experienced -39.5°C.

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