Do you Know what is Absolute zero?

Absolute  zero, 0  Kelvin, 459.67° Fahrenheit, or 273.15° Celsius, is the minimum possible  temperature: the state in which all  motion of the particles in a substance has minimum motion. Equivalently, when the entropy of a substance has been reduced to zero, the substance is at  absolute zero.  Although the third law of thermodynamics declares that it is impossible to cool a substance all the way to absolute zero, temperatures of only a few billionths of a degree Kelvin have  been achieved in the laboratory in the last few years.

Atoms may be cooled by many methods, but  laser cooling and trapping have  proved essential achieving the lowest possible temperatures.  A laser beam can cool atoms that are fired in a direction contrary to the beam because when the atoms encounter photons, they absorb them if their  energy is at a value acceptable to the atom (atoms can only absorb and emit photons of certain energies). If a  photon is absorbed, its  momentum is transferred to the atom; if the atom and photon were originally traveling in opposite directions, this slows the atom down, which is equivalent to cooling it.

The third law of thermodynamics, however, dictates that absolute zero can never be achieved.  The third states that the entropy of a perfect  crystal is zero at absolute zero. If the particles comprising a substance are not ordered as a perfect crystal, then their entropy  cannot be zero.  At any temperature above zero, however, imperfections in the crystal lattice will be present (induced by thermal motion), and to remove  them requires compensatory motion, which itself leaves a residue of imperfection.  Another way of stating this dilemma is that as the temperature of a substance approaches absolute zero, it becomes increasingly more difficult to remove  heat from the substance while decreasing its entropy. Consequently, absolute zero can be approached but never attained. 

When atoms have  been cooled to within millionths or billionths of a degree of absolute zero, a number of important phenomena appear, such as the creation of Bose-Einstein condensates, so called because they were predicted in 1924 by  German physicist  Albert Einstein (1879–1955) and Indian physicist Satyendranath Bose (1894–1974).  According to Bose and Einstein, bosons— particles having an  integral value of the property termed “spin”—are allowed to coexist locally in the same quantum energy state. (Fermions, particles that have  half-integer spin values, cannot coexist locally in the same energy state; electrons are fermions, and so cannot share  electron orbitals in atoms.)  At temperatures far above absolute zero, large collections of bosons (e.g., rubidium atoms) are excited by thermal energy to occupy a wide variety of energy states, but near absolute zero, some or all of the bosons will lapse into an identical, low-energy state.  A collection of bosons in this condition is a Bose-Einstein condensate. Bose-Einstein condensates were first produced, with the help of laser cooling and trapping, in 1995. Since that time, numerous researchers have  produced them and investigated their properties.