An exotic state of matter in which "giant atoms" filled with smaller atoms can appear or create ...
Scientists from the Vienna Polytechnic University have discovered a new state of matter. They figured out that there could be other atoms between the nucleus of an atom and the electrons. Atoms are the smallest particles that make up everything around us: everything that surrounds us consists of molecules made of atoms. They cannot be seen using any magnifying devices due to their incredibly small size. But atoms must also be composed of something. This means that even smaller particles must exist. I say right away that this is a rather difficult topic to understand, so there is a lot of text, and you need to read it thoughtfully. However, it is extremely exciting to know about particles so small that you cannot even see.
Atoms and their structure
Already ancient Greek scientists guessed about the existence of the smallest chemical particles that make up any object and organism. And if in the XVII-XVIII centuries. chemists were sure that the atom is an indivisible elementary particle, then at the turn of the XIX-XX centuries, it was experimentally proved that the atom is not indivisible.
An atom, being a microscopic particle of matter, consists of a nucleus and electrons. The nucleus is 10,000 times smaller than an atom, but almost all of its mass is concentrated in the nucleus. The main characteristic of an atomic nucleus is that it has a positive charge and consists of protons and neutrons. Protons are positively charged, while neutrons have no charge (they are neutral).
They are connected to each other through a strong nuclear force. The mass of a proton is approximately equal to the mass of a neutron, but at the same time it is 1840 times greater than the mass of an electron. In chemistry, protons and neutrons have a common name - nucleons. The atom itself is electrically neutral.
An electron is a negatively charged particle. The electron shell consists of electrons moving around the nucleus. Electrons have the properties of being attracted to the nucleus, and between each other they are influenced by the Coulomb interaction. To overcome the attraction of the nucleus, the electrons must receive energy from an external source. The farther the electron is from the nucleus, the less energy is needed for this.
Models of atoms
For a long time, scientists have sought to understand the nature of the atom. At an early stage, the ancient Greek philosopher Democritus made a great contribution. Although now his theory seems trivial and too simple to us, at the time when the concept of elementary particles was just beginning to emerge, his theory of pieces of matter was taken quite seriously. Democritus believed that the properties of any substance depend on the shape, mass and other characteristics of atoms. So, for example, near the fire, he believed, sharp atoms - therefore the fire burns; the atoms of water are smooth, so it is able to flow; in solid objects, in his opinion, the atoms were rough.
In 1904, J.J. Thomson proposed his own model of the atom. The main provisions of the theory boiled down to the fact that the atom was represented as a positively charged body, inside which there were electrons with a negative charge. Later, this theory was refuted by E. Rutherford.
Also in 1904, the Japanese physicist H. Nagaoka proposed an early planetary model of the atom by analogy with the planet Saturn. According to this theory, electrons are combined into rings and revolve around a positively charged nucleus. This theory turned out to be wrong.
In 1911, E. Rutherford, after doing a series of experiments, concluded that the atom is similar in structure to the planetary system. After all, electrons, like planets, move in orbits around a heavy, positively charged nucleus. However, this description contradicted classical electrodynamics. Then the Danish physicist Niels Bohr in 1913 introduced the postulates, the essence of which was that the electron, being in some special states, does not radiate energy. Thus, Bohr's postulates showed that classical mechanics is inapplicable to atoms. The planetary model described by Rutherford and supplemented by Bohr was called the Bohr-Rutherford planetary model.
A new state of matter
An exotic state of matter in which "giant atoms" filled with smaller atoms can appear or create, scientists call the "Rydberg polaron". Weak bonds between these atoms are formed at low temperatures. As a result, scientists managed to combine the two states of matter. The first is the Bose-Einstein condensate, which is formed by atoms at zero temperature. The second is "Rydberg atoms", in which electrons revolve around the nucleus at a great distance.
The average distance between an electron and an atomic nucleus can reach several hundred nanometers, that is, a thousand times the radius of a hydrogen atom. The Bose-Einstein condensate was created by strontium atoms. Using a laser, scientists transferred energy to one of these atoms, turning it into a Rydberg atom with a huge radius. Depending on the radius of the Rydberg atom and the density of the Bose-Einstein condensate, up to 170 additional strontium atoms can be trapped in a huge electron orbit.
Atoms carry no electrical charge, so they only have a minimal effect on the electron. An electron is scattered only slightly on contact with neutral atoms, without leaving its orbit. The quantum physics of slow electrons allows for a kind of scattering that does not transfer the electron to another state.
As computer simulations show, this relatively weak type of interaction reduces the total energy of the system, and therefore a bond is formed between the Rydberg atom and other atoms within the electron orbit. This is a very unusual situation, usually we are dealing with charged nuclei binding electrons around them. Here we have an electron linking neutral atoms. This bond is much weaker than the bond between atoms in a crystal. Therefore, this exotic state of matter, called Rydberg polarons, can only be detected at very low temperatures. If the particles moved faster, the bond would break. For us, this new loosely bound state of matter is an exciting new opportunity to explore the physics of ultracold atoms. Thus, the properties of the Bose-Einstein condensate on a very small scale can be investigated with very high accuracy.
Scientists at the Vienna Polytechnic University were able to apply Poincaré's repetition theorem to a multiparticle quantum system. This was done despite the fact that quantum states live according to completely different rules.