Monday, January 3, 2011

What is the point of absolute zero? Why do we even have such a term? - from Jen in Aurora

Thanks Jen, for another great question!  See, folks, follow her example and write in some more!  The Science Lady is super excited about such a science-y question. Absolute zero is defined as 0 Kelvin (K), −273.15°C, or −459.67°F.  That is cold!!!  Scientists have never been able to cool anything down to this temperature, ever. For reference, if you've ever seen or played with dry ice before (solid CO2), dry ice is at −78.5 °C. So what is the point of absolute zero?  It actually is important!  It is the reference point from which all other temperature is measured.  It is the reference point and baseline for thermodynamic tables and psychometric charts (think refrigeration, heating, cooling, distillation, chemical reactions, etc.).  It is the zero point in thousands of scientific equations and allows us to explain thermodynamic phenomena mathematically. So, it is mathematically required.  "Yawn," you say?  Well, absolute zero is the point at which matter loses all thermal energy, and atoms cease to vibrate. Weird stuff happens near absolute zero. For example, the boiling point of liquid helium is only about 4 Kelvin (depends on the atmospheric pressure)! Liquid helium is used to chill super-conducting magnets, such as those used in nuclear magnetic resonance (NMR) and fancy particle accelerators.  Liquid helium allows scientists to smash particles together, and study cool stuff like quarks, dark matter, and teleportation (for real! seriously!).  If you were an electron, you could say "Beam me up, Scottie!"  Though we will probably never be able to achieve absolute zero on Earth, some scientists would like to try it in space.  Perhaps someday.  Just because we can't see or feel something does not make it unnecessary.  For example, we cannot accelerate anything to the speed of light (299,792,458 meters per second, or approximately 186,282 miles per second) because the force required to accelerate an object becomes infinitely huge as you approach the speed of light. However, we use the speed of light to calculate the distance between us and other planets, or us and other galaxies.  Fun fact: In February 2003, the Boomerang Nebula was observed to have been releasing gases at a speed of 500,000 km/h (over 300,000 mph) for the last 1,500 years. This has cooled it down to approximately 1 K, as deduced by astronomical observation. This is the lowest natural temperature ever recorded!     

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