Presentation on theme: "Universe: from Beginning to End"— Presentation transcript:
1Universe: from Beginning to End Brief History of Universeform Birth to DeathOR
2What is matter?Experiments at Fermilab have helped defined the proton, a particle inside the atom’s nucleus, and proton’s substructure of quarks. Study the top quark may give clues to the scientific mystery of why matter has mass
84n is tetraneutron a bound state of four neutron?
9Final State: Nucleons in continuum spectrum 4He, 3He, 3Hg, p, mFinal State: Nucleons in continuum spectrum2ds/dWTransition operator
10From Elementary Particles to Stars We discussed the tiniest object in the universe – the neutron, and existence of the bineutron, trineutron and tetraneutron.Now we leap to the largest – stars especially, neutron stars
11History of our Universe t=0 The Big Bang Universe originated in the explosion of a primordial fireball0<t<10-43 Seconds.General Relativity should not be valid and should be replaced by a new theory which incorporates the principles of quantum theory.We do not know anything about this epoch
1210-43 <t<1 Seconds.During this period the universe expanded and the matter density dropped from about 1092 g/cm3 to ~ 106 g/cm3.Matter in the Universe consisted primarily of the very high energy elementary particles. Exotic elementary particles (m, p, W, S, K, L) decayed and at the end of this epoch we had “soup” of photons, neutrinos, electrons, positrons, protons, neutrons.The temperature of the matter cooled to about C.There were about five times as many protons as neutrons
141Second<t<1000 Seconds Density of the ‘soup” dropped from about 106 g/cm3 to 0.5 g/cm3Temperature dropped from ~ C to C.e-+e+ 2gDuring this period was nucleosynthesis: protons and neutrons formed elements: 2D, 4He …p +p 2D + e+ + np + 2D 3He +g3He + 3He 4He + p + pProton-proton cycle : 4p 4He + 2e+ + 2n + 2g4He + 4He 8Be +g4He + 8Be 12C +g
151000 Seconds<t< 100,000 Years The Universe continued expanded rapidly and coolThe important constituents of the soup were photons, protons, helium nuclei and free electrons.At the end of this epoch, the temperature of the “soup” dropped to ~ C and the electrons combined with the protons, helium nuclei to form neutral hydrogen and helium atoms.There were no longer any charged particles and electromagnetic radiation decoupled from matter
17100,000 Years<t<8 to 18 Billion Years (Present Era) Universe continued to expand. Electromagnetic radiation fills the entire Universe. And the temperature dropped to ~ 3 0K.Small inhomogeneities in the mater distribution began to grow under their own self-gravitation attraction.The galaxies, star clusters and stars formation.
18The process of stellar evolution from the birth to the death of the star depends on the mass of the star.If the star has mass less than about 1.4 solar masses the star collapses under the action of gravity and becomes a white dwarfIf mass is greater than 1.4 solar mass the stars follow to quite different scenario.High-energy collisions breaking iron into helium nuclei, and eventually into protons and neutrons56Fe 13 4He + 4n4He 2p + 2nThene- + p n +nThe star begins to contract rapidly toward forming an enormously dense neutron starThe core of a neutron star contracts to the point at which all neutrons are as close together as they are in a nucleus.
20Black HolesIf the mass M of the star is compressed to such small size that the escape speed exceeds the speed of light, the mass M forms aBLACK HOLE
21Big CrunchUniverse stops expanding at some time in the future, will then contract again down to its initial, highly condensed state in a finite time…starts another expansion phaseOr will it just go on contracting and then … … new Big Bang