What is absolute zero said to be?

Answer 1

Absolute zero is the coldest temperature possible. What we think of as 'temperature' is really a measurement of how quickly the atoms in a particular substance are vibrating. If the atoms in a substance are vibrating quickly, this is because of the energy they possess, and therefore when we measure what we call the 'temperature' of the substace, it will be high. If the atoms are vibrating less quickly, then any temperature measurement will be lower. There comes a time, however, when the atoms stop vibrating altogether, and are still. This is what we call 'Absolute zero' and, because atoms cannot vibrate any slower than absolutely still, this is the lowest temperature attainable. The temperature is only theorical - by the laws of thermodynamics it can never be reached - because to remove the last bit of heat from a substance we will always need something colder. Therefore, although we can get very near absolute zero (at the moment scientists have reached a fraction of a thousandth of a degree above it) we can never actually get there. The accepted value for Absolute zero is - 273.15 degrees Celsius (Centigrade). To give some idea of how cold this is, a domestic freezer is -18 degrees, winter in the Antarctic seldom goes below -40 degrees, and nitrogen in the air becomes a liquid at -196 degrees. In physics, sometimes temperature is measured in Kelvins also. Absolute zero is 0 Kelvins (0K) and therefore the freezing point of water - zero degrees Celsius is 273.15K, and the boiling point of water (100 degrees Celsius) is 373.15K. using the Kelvin temperatue scale therefore removes the clumsy minus figures that the Celsius scale has to use when dealing with such low temperatures.