Absolute Zero
Written by John Carl Villanueva
Gravity Probe B is cooled almost absolute zero.
Absolute zero pertains to that temperature in the Kelvin scale that is equivalent to zero. This corresponds to -273.15º in the Celsius scale. In Classical Physics, all molecular motions cease to exist at this temperature. However, in the quantum mechanical realm according to the Heisenberg Principle, molecules still oscillate slightly even at this point … even if you wouldn't know for sure where the molecule would be.
Although no scientist has ever achieved absolute zero, this concept was first introduced during the early years of Thermodynamics. While playing around with gases by varying temperatures, volumes, and pressures, it was found that when plotting data into graphs of pressure vs temperature, each of the gases' graphs appeared to converge to a single point on the temperature axis when extrapolated backwards.
This point was found to be -273.15º Celsius. This was then called absolute zero and from it, the Kelvin scale was derived. It was believed that all particles had zero energies at this temperature … until of course Heisenberg and his crew of quantum mechanics came along.
As mentioned earlier, no scientist has ever brought anything to absolute zero. However, researchers from MIT and NASA have come pretty darn close. Their coolest record? – one-half billionth degree above absolute zero. To achieve this, they made use of a technology very similar to one that led to the Nobel Prize for Physics back in 2001. Ironically, that was one of the hottest news in the world of Physics at that time.
There are lot of places in the vast empty areas of outer space that are really very cold generally because of the lack of particles. Remember that, as you bring down pressure, the temperature also follows. Using this relationship is how they found out about absolute zero in the first place.
So far, the coldest known region in outer space is the Boomerang Nebula, at -272.15ºC or 1 K. It's around 5,000 light-years from our planet, in the constellation Centaurus. It's moving further away, rapidly expanding at the same time and consequently causing the record-making temperature drop.
A great deal of interest is focused on achieving near-absolute zero temperatures. This is because some very beneficial phenomena of matter take place at these points. Among them are superconductivity and superfluidity. A superconductor, for example, is devoid of any electrical resistance. You could just imagine, therefore, the efficiency of devices & machines when this concept is fully applied.
You can read more about absolute zero here in Universe Today. Want to read about the coldest temperature ever created? We've also written about how small nebulae are close to these temperatures.
There's more about it at NASA. Here are a couple of sources there:
Here are two episodes at Astronomy Cast that you might want to check out as well:
Filed under: Astronomy
