|
|
|
| Current Issue |
|
|
| Resources |
|
|
|
Approaching Absolute Zero
| Article
# : |
19649 |
|
|
Section : |
NATURAL SCIENCE
|
| Issue
Date : |
10 / 1991 |
3,133 Words |
| Author
: |
Matthew Kohler
Matthew Kohler is pursuing a doctorate in physics at the
University of Colorado at Boulder. |
Professors Neptune and Pluto were walking across their college campus in the dead of winter:
"Hmmm," said Professor Neptune, brushing snow off his down jacket, "these air molecules are moving quite slowly and their velocity distribution is sharply peaked."
"You mean it's cold," shivered his friend, who was regretting leaving his own down jacket at home and didn't think scientists always had to talk like scientists.
"Yes, quite," said the warmer of the two, "I hope these oxygen and nitrogen molecules don't slow down any more or they will liquefy. Then we would suffocate."
"You know as well as I that it never gets that cold on earth. Even in the Antarctic it's always far warmer than liquid air."
"Ah, but the Antarctic isn't the coldest place on Earth," countered Neptune. "I even have some liquid nitrogen in my lab and it only costs me a dollar a quart, and since the air is almost 80 percent nitrogen there's plenty..."
"I meant the weather never gets that cold," interrupted the colder scientist, shaking his head. After a moment, he added, "fortunately."
Neptune went on as if he hadn't heard. "Even helium can be liquefied right here on earth, but, of course, that's much more expensive. It's only about 73 degrees colder than liquid nitrogen but what a long 73 degrees! I can't even imagine what it would take to get that last 4 degrees to absolute zero."
"It's impossible to get to absolute zero," muttered his friend. "Don't tell me you've forgotten the laws of thermodynamics!"
Absolute zero is the lowest temperature imaginable where atoms and molecules, normally in incessant motion, stop. This temperature is the zero point on the Kelvin scale (-273.15oC, or -459.67oF). And it will never be reached. One of the laws of thermodynamics states that it is impossible to cool anything to absolute zero. The closer something gets, the greater the difficulty in getting it closer still.
Although absolute zero is forever out of reach, it is possible to get extremely close. In
...
Read Full Article
Look for this article in Ask.com
|
|
