In the days before his death, physicist Stephen Hawking worked on an interesting article. According to some experts, it could be Hawking's most important contribution to science. In the article, Hawking and his Belgian colleague Thomas Hertog write about one of the greatest mysteries of physics: parallel universes.
Events take place in chronological order, the past influences the present and the present is important for the future. But imagine you fall off your bike tomorrow and break your leg - and have to sit still with your leg in plaster today. It can be that way in so-called quantum mechanics, a branch of physics that deals with the level of atoms and particles.
When the dishwasher is ready, the plates are usually dry, but the plastic boxes are still wet. This is because the different materials do not absorb the heat to the same extent. Crockery, glasses and cutlery have a much larger heat capacity than plastic. They also generally consist of thicker materials than plastic and can therefore store more heat.
5 percent visible matter, 27 percent dark matter and 68 percent dark energy. That is the formula of the universe according to traditional cosmology. But nobody knows what dark matter and dark energy actually are. That is why physicists have been using high-tech equipment to find out for ten years what the universe really consists of.
Coal consists mainly of carbon (C) and hydrogen (H). These two atoms form a strong chemical bond, which can be broken by adding energy in the form of heat. Carbon and hydrogen bind to oxygen during combustion. This process releases more energy than is necessary to break the bond between C and H.
We divide radioactive or rather ionizing radiation into alpha, beta and gamma radiation. Alpha radiation is the most dangerous of the three. Alpha radiation consists of the nuclei of helium atoms that run at 10,000 to 20,000 km / s. Compared to ordinary electrons - beta particles - it is immediately clear why they are so dangerous: if the beta particle were as large as a pea, an alpha particle would be a steel ball with a mass of 8 kilos and a diameter of 12 centimeters.
What is radioactivity? Radioactive substances contain too many neutrons in the atomic nucleus compared to the number of protons. This makes the atoms unstable, which they restore by emitting radiation. The type of radiation depends on the size of the atom. There are three types of radiation: 1. Alpha radiation: helium nuclei Large radioactive atoms emit helium nuclei, that is, nuclei of two protons and two neutrons.
The three American scientists Rainer Weiss, Barry C. Barish and Kip S. Thorne have won the Nobel Prize in Physics this year. This honor is due to them for their work at LIGO - Laser Interferometer Gravitational-Wave Observatory - a research project in which thousands of scientists from 20 countries participate.
What is gravity? Gravity is one of the four fundamental forces of nature that prevail in the universe. In daily life you only notice two forces: gravity and electromagnetic force. Both forces of nature have an infinite range. That means that all masses in the universe attract each other through gravity, and that the electromagnetic force in the form of light can be seen even from distant galaxies.
What do we know There is no evidence for the existence of more dimensions than the four that Einstein worked with. However, many physicists still think that they must exist, because there are important theories that would not work without those dimensions. This is especially true for the so-called string theory, which can only be applied with seven extra dimensions.
Albert Einstein is known for his abstract theories and was only concerned with their practical application to a limited extent. But with his ideas about time, space and light, Albert Einstein inspired entire generations of inventors of new technology, with which he is indirectly responsible for a large number of inventions that we now take for granted.
Albert Einstein: a special genius Albert Einstein only learned to talk when he was four, he failed the entrance examination of the technical college and had a bad memory for data and telephone numbers. Yet he grew into one of the greatest scientific thinkers of all time, and Einstein embodied the image of the eccentric genius with its colorful character traits.
The oval Brazil nut is different from other nuts. This is because it contains a small amount of the radioactive element radium, so that it has a radioactivity of approximately 444 Bq / kg. That is 1000 times as much as most other foods, but much less than the EU limit of 600 Bq / kg.
Time travel Bran Stark is paralyzed from the waist down, but can travel through time. Is time travel possible? In Game of Thrones, Bran Stark can travel through time and influence past and future. Such time travel is not really possible, but according to a new quantum theory, the future can in principle change the past.
Perhaps we live in a universe with more spatial dimensions than the three - length, width and height - that we know. In any case, physicists work on theories in which more dimensions play a role than three in space and one in time. The researchers try to unite the two major physics theories, quantum mechanics and the theory of relativity, in one 'theory of everything'.
Cryostat: Device cools the brain of the computer. At the bottom of a special cooling device, a cryostat, is the brain of the computer, the quantum chip. With each deeper floor of the device, the temperature also drops. This allows the metal current to conduct without resistance. Graham Carlow / IBM Research Protection: Hoods and liquid helium approach absolute zero.
Imagine a ball lying on the floor. Like all objects, this ball has properties that describe its three-dimensional shape: it is spherical and has a certain diameter that determines the circumference - just like all other round objects. Yet this ball is completely different, because the shape also depends on the fourth dimension: time.
When astronaut Jack Lousma returned to earth after a two-month stay in the American space station Skylab, he put his aftershave bottle in the middle of the air one day. A bang and a cloud of broken glass reminded him that this was a bad idea. At the space station he was used to all things floating around him weightlessly, but in the bathroom on earth there are very different rules.
First there was nothing and suddenly everything came into existence: dimensions, time, natural laws and the matter that would later form stars, planets and life. That is, at least, the genesis of the universe according to the accepted theory, the big bang theory. But the formation of the universe remains misted in many respects.
Magnetism protects life on earth Magnetism is of great importance for life on earth. The earth is in fact one large magnet with a north and a south pole, and the earth's magnetic field protects us against harmful particles from the sun and from space. If the Earth's magnetic field did not deflect this radiation, all life would largely disappear from our planet.
Can you break an uncooked spathettis line in just two pieces? This question has been occupying material researchers and physicists for decades - including the American Nobel Prize winner Richard Feynman, who never found out. In 2006, two French physicists received the Ig Nobel Prize for unlikely research because they had demonstrated that spaghetti always breaks into three or four pieces.