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400 BCE
Democritus's Atomos
Democritus suggested that everything in the world is made out of tiny particles surrounded by the empty space and they varied in size and shape. He called them 'atomos' which is Greek for "indivisible". But this idea was opposed by the another philosopher at that time, Aristotle by saying thighs are made up with 4 elements called earth, wind, fire and water. -
John Dolton's atomic theory
John Dolton introduced 5 postulated in his atomic theory
1. Matter is made up of atoms that are indivisible and indestructible.
2. All atoms of an element are identical.
3. Atoms of different elements have different weights and different chemical properties.
4. Atoms of different elements combine in simple whole numbers to form compounds.
5. Atoms cannot be created or destroyed. When a compound decomposes, the atoms are recovered unchanged. -
Thomson's Discovery of electron
J.J. Thomson's discovered electron in his experiment with cathode ray in a Crook's tube in 1897 and introduced plump podium atomic structure around the same time. He won the Nobel price in 1906 for his discovery of electron.
Discovery of electron -
Rutherford's discovery of Nucleus and Proton
Ernest Rutherford found the Nucleus of an atom from the gold foil experiment conducted by Geiger and Marsden. Moreover, he named the H+ nuclear found by Eugen Goldstein in 1886 as proton. After, he introduced the nuclear module of atomic structure in 9011.
Proton Discovery
Gold Foil experiment -
Niles Bohr's Planetary Model
Bohr modified Rutherford's model of atom by making the electron in Hydrogen atom moving around in orbits of fixed size and energies. According to the Bohr's model;
1.Electrons orbit the nucleus at fixed energy levels
2. Orbits further from the nucleus exist at higher energy levels
3. When electrons return to a lower energy level, they emit energy in the form of light -
Louise de Broglie wave particle duality
A French physicist Louise de Broglie first suggested a wave nature of electron. Moreover, he introduced an equation for this as an extend to Bohr's model.
De Broglie Equation
wave particle duality simulation -
Schrödinger's equation
The Schrodinger equation can be used to find the allowed energy levels of quantum mechanical systems. Basically, it showed the electrons position in atom as a probability cloud. This allowed to explain the double slit experiment as well. Problem of this equation is it described the particles as only wave as didn't consider there internal properties.
Equation -
Dirac's equation predicts antiparticles
Schrödinger's equation agreed with only slow moving particles and therefore didn't alien with Einstein's theory of relativity. When finding a solution to this problem his derivation of relativistic wave equation implied the existence of a new form of matter, a mirror version of the matter currently known. This is called the antimatter. Therefore, Dirac's equation predicted the existence of antimatter. -
Discovery of 1st particle of antimatter by Carl Anderson
In the year 1932 Caltech Carl Anderson discovered the anti particle of positron which is called positron. To do this he had to built a cloud chamber to determine the composition of cosmic rays, high-energy particles that rain down from space. For this discovery he won the Nobel prize for physics in 1936. -
James Chadwick discovery of Neutron
By the year 1920 physicists knew there should be a neutral particle in an atom due to the extra mass in the nuclear. But they were unable to detect it at the time. During the experiment he hit a Be sheet by alpha particles and found strange radiation of high energy that appears to be neutrons. He won the Nobel prize in 1935 fro this discovery. -
Invention of cyclotron
In 1929 Ernest Lawrence in University of California, Berkeley invented the cyclotron, a device for accelerating nuclear particles to high velocities without the use of high voltages, i.e. a partial accelerator. Lawrence was granted US patent 1948384 for the cyclotron on 2 February 1934. After the machine was used in the following years to bombard atoms of various elements with swiftly moving particles. His this invention lead to many scientific discoveries in the years forward. -
Antiproton
Antiproton were first produced and identified by Emilio Segrè, Owen Chamberlain in a proton accelerator called the Bevatron at the radiation laboratory in the University of California at Berkeley. They found that a sub atomic particle which is similar to the proton except the charge. They won the Nobel price for this discovery in 1959. -
The Bevatron discovers the antineutron
After one year of the discovery of the antiproton Bruce Cork, Glen Lambertson, Oreste Piccioni and William Wenzel discoverd the anti neutron in Bevatron (Lawrence Berkeley National Laboratory).Antineutrons were created when antiprotons in the beam exchanged their negative charge with nearby protons, which have a positive charge. The antineutrons were detected through their annihilation reactions with neutrons and protons. -
Concept of Quarks
Physicists Murray Gell-Mann and George Zweig independently proposed the existence of subatomic particle know as quarks while working independently on a theory for strong interaction symmetry in particle physics. with the time physicist have able to fined other types of subatomic particles and find it lead to the creation of standard model of particle physics. -
Antinuclei
By 1965, all three particles that make up atoms (electrons, protons and neutrons) were known to each have an antiparticle. The next big challenge was to create an antinuclei. This goal was achieved in 1965 with the observation of the antideuteron, a nucleus of antimatter. Teams of two physicists simultaneously discover this one at CERN and one at Alternating Gradient Synchrotron (AGS). -
First proton-antiproton collisions
In 1960s Bruno Scheck proposed the 1st electron and position collision and after overcoming many issues it was finally achieved in 1981 at Cern Super Proton Synchrotron (SPS). Simon van der Meer and Carlo Rubbia won the Nobel price for this discovery. By the year 1984 when it was shutdown, it had produced many important results, including indications that protons contain smaller constituents, ultimately identified as quarks and gluons. -
Discovery of antiatom
A team led by Walter Oelert created atoms of antihydrogen for the first time at CERN’s Low Energy Antiproton Ring (LEAR) facility -
Discovery of Higgs boson
Higgs boson aka god particle first described by peter Higgs with the help of other physicist. Discovery of this particle suggests that the existence of Higgs field. According to this theory particles get their mass as a result of interaction with this Higgs field. you can find more details of this particle from the video below.
The basics of the Higgs boson -
Yet Remain
In the last centuries through the discoveries of this matter and antimatter allowed us to better understand our universe better. yet there are may question remain that should be answered. Questions like why there are more matter than antimatter. As the history has shown to us, eventually we'll be able to come up with better answers for these questions and lead the humanity to a better era.
