‘At temperatures close to absolute zero atoms and molecules lose their separate identities and merge into a single ‘super-atom’. This ‘super-atom’ is known as Bose-Einstein condensate’
Like solid, liquid, gas and plasma (hot ionized gas), Bose-Einstein condensate is a state of matter.
Velocity in a gas of rubidium as it is cooled: the starting material is on the left, and Bose–Einstein condensate is on the right. (Photo credit: Wikipedia)
In quantum mechanics, elementary particles can, in some circumstances, behave like waves. The waves – which are waves of probability – describe where a particle is most likely to be at a given moment. The uncertainty principle dictates that it is impossible to know the exact position of a particle. In 1924, while in Germany, Einstein predicted, based on ideas originally suggested by Indian-born Bose, that when atoms approach absolute zero the waves would expand and finally overlap; the elementary particles of which they are composed all merge into a single quantum state.
This state is now known as Bose-Einstein condensate.
‘The maximum possible mass of a white dwarf star is 1.4 times the Sun’s mass’
The Chandrasekhar limit is a physical constant. It is the greatest mass a white dwarf star can have before it goes supernova, approximately 1.44 solar masses. Chandrasekhar showed that it is impossible for a white dwarf star, which is supported solely by electron degeneracy pressure, to be stable if its mass is greater than 1.44 times the mass of the Sun. If such a star does not completely exhaust its thermonuclear fuel, then the limiting mass may be slightly larger.
Above this limit a star has too much mass to become a white dwarf after gravitational collapse. A star of greater mass will become a neutron star or a black hole.
The radius of a black hole is the radius of the event horizon surrounding it. This is the Schwarzschild radius, after the German astronomer Karl Schwarzschild (1873-1916) who in 1916 predicted the existence of black holes.
The Schwarzschild radius is roughly equal to three times the weight of the black hole in solar masses. A black hole weighing as much as the Sun would have a radius of 3 kilometres, one with the mass of the Earth would have a radius of only 4.5 millimetres.
A black hole’s effects occur within ten Schwarzschild radii of its centre.