Absolute Zero
Why Is A Negative Number Called Absolute Zero?
- By Sarah Zielinski
- Smithsonian.com, January 01, 2008, Subscribe
Those who have studied some physics might remember why minus 459.67 Fahrenheit is called "absolute zero," but for the rest, it's probably a bit confusing. Switching to Celsius won't help; absolute zero is minus 273.15 degrees on that scale. Is absolute zero ever zero degrees? To find the answer, one needs to look to a scientific temperature scale called Kelvin and how it evolved.
The Fahrenheit scale used in the United States dates back to the early 1700s, a time when scientists realized that they needed a way to measure heat and cold and were inventing thermometers. German physicist Gabriel Daniel Fahrenheit is credited as the first to use mercury in a thermometer, and he created a measurement scale to go along with his invention. On Fahrenheit's scale, zero degrees was the temperature of a mixture of equal parts ice, water, and salt, and 212 degrees was the temperature at which water boiled.
Though Fahrenheit's temperature scale became widely used, other scientists of the time experimented with their own. In 1742, Swedish astronomer Anders Celsius used a 100-degree, or centigrade, scale that set the freezing point of water at zero and the boiling point at 100. (In 1948, the centigrade scale was renamed the Celsius scale by the Ninth General Conference of Weights and Measures in honor of its inventor.) With its similarity to the 10-based metric system, the Celsius scale became the standard in most of the world.
By the early 1800s, scientists studying the behavior of gases had determined that the lowest possible temperature for anything in the universe was minus 273.15 Celsius. And in 1848, William Thomson (who would later be made a baron with the title Lord Kelvin) suggested that it would be convenient to call that temperature "absolute zero" and create a new scale starting there that would eliminate all negative temperatures. The idea caught on, at least in science, and that absolute scale of temperature is now known as the Kelvin scale.
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Comments (11)
What is the si unit for pressure
Posted by Josey espinoza on March 4,2013 | 01:30 PM
All this information about absolute zero is fascinating. Maybe somebody would like to explain how absolute zero temperature is achieved? I saw a DVD movie that described it, and the Einstein Bose theory was explained too. Really fascinating stuff, but a bit over my head. I was not aware that temperatures below absolute zero had been achieved. There is a Danish scientist (a female who's name I do not recall) who used extreme cold to slow down light speed to about 30 miles per hour using the Einstein-Bose idea. perhaps someone would like to comment on this.
Posted by Doyle Hall on November 23,2011 | 01:16 PM
below absolute zero the subatomic particles get very brittle when they break apart the left over matter is useless tiny bits of subatomic particle have no charge there non conductive and they emit no radiation unlike atoms who admit radiation when they come back from absolute zero.
posted 2-26-10
Posted by Brian k. Bachman on February 26,2010 | 06:15 PM
when temperatures fall below absolute zero, the sub-atomic particles get very brittle, if and when they shatter the minute pieces are unusable. they will never be able to reunite to make any identifiable product in the nuclei of an atom
Posted by Brian K. Bachman on February 26,2010 | 05:53 PM
Thank you Thank you Thank you.
You've helped me so much.
BTW your article is amazing.
Posted by layla on February 16,2010 | 02:50 AM
thanks to you!! i had answered my assignment at chemistry...
Posted by hazel marre faith lacang on January 4,2010 | 08:26 AM
I LIKED YOUR EXPLANATION. BUT I WANT TO KNOW WHAT HAPPENS WHEN ANY SUBSTANCE REACHES TO ABSOLUTE ZERO TEMPERATURE?
Posted by amit on July 24,2009 | 07:36 AM
Thanks for the article; it helped me refresh my memory. It would have been even more informative if you had included the temperature conversion factors between various scales.
Posted by Sandeep L S on November 25,2008 | 01:58 AM
Topics like this is very informative. I have encountered these units of measure for temperature when solving problems in my college engineering days. I would like to thank the author for this article.
Posted by Mario H. Pinto, Jr. on November 10,2008 | 12:19 AM
Reading the coldest place, it looks like we are on the verge of knowing how we can use light to tavel into space. Then useing light? slowing light down is as important as light travel. if you can slow down light, then the possiblity of slowing down time? due to light is time, as time is light.
Posted by Frank G on November 10,2008 | 08:41 PM
Sarah Zielinski: Both of these articles; absolute zero and The Coldest Place in the Universe were excellent articles. Not having a scientific background but been possessed of significant interest in these types of things from a lay-mans perspective, I think your style and quality of information was excellent. The previous post concerning Dr. Sam Collins of MIT would have added interest to a history tangent on the article. I really enjoyed your journalistic style and the info. Dave Brown, Costa Mesa CA.
Posted by David Brown on January 22,2008 | 05:46 PM
What has been the role of Dr. Sam Collins of MIT, retired in 1974 or there abouts. It is my understanding that he developed the first or workable helium cryostat that enabled scientists to be the march toward absolute. I believe his work was widely recognized, however no mention of him in this particular article. I would appreciate any light you could shed on his contributions at MIT. Respectfully,
Posted by Joe C. Collins on December 26,2007 | 10:37 PM