Is Below Zero Kelvin Possible in Outer Space? Curiosity and Scientific Theory

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Discussion Overview

The discussion centers around the concept of temperatures below absolute zero (0 K), particularly in the context of outer space and theoretical systems like lasers. Participants explore the implications of negative temperatures, the limitations of cooling to absolute zero, and the nature of temperature as defined in statistical mechanics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that 0 K is the lowest temperature possible, with practical limitations preventing cooling to this point.
  • Others mention that space has a temperature of approximately 2.7 K due to Cosmic Background Radiation.
  • One participant introduces the idea that in certain systems, like lasers, negative temperatures can occur due to population inversion, where entropy decreases with energy increase.
  • Another participant clarifies that objects with negative temperatures are not colder than absolute zero but are instead hotter than any positive temperature, leading to heat flow from these states to equilibrium states.
  • Some participants express confusion over the concept of negative temperatures and suggest it may be a misinterpretation of temperature as a physical quantity.
  • There is a discussion about the mathematical treatment of negative temperatures in solid state physics, with some arguing that it may not reflect a physical reality.
  • One participant suggests that technological advancement may be necessary to achieve negative temperatures, while another counters that it is not merely a technological barrier but rather a conceptual issue.

Areas of Agreement / Disagreement

Participants generally agree that 0 K is a thermodynamic limit that cannot be reached, but there are competing views regarding the nature and implications of negative temperatures, with no consensus on whether they represent a real physical state or a mathematical abstraction.

Contextual Notes

The discussion highlights limitations in understanding temperature in extreme conditions, the dependence on definitions of temperature, and the unresolved nature of the implications of negative temperatures in various systems.

jaredmt
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is this possible anywhere?
i know 0 kalvin is the lowest temperature possible that we've been able to attain. but is it possible that in outerspace where there is no heat from sun, that it gets below zero kalvin?

im just curious. I am not sure wether this was "proven" to be the lowest possible temp or just the lowest temp we've been able to get. because i do know that no matter how hard you try to take heat out of something, more heat will just keep going back into it at the same time
 
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According to current understanding, no temperature below 0 K exists. Also, it is not possible from a practical perspective to cool an object to 0 K (the process would take an infinite amount of time). The lowest humans have achieved is less than one billionth of a Kelvin, far colder than interstellar space, which is approximately 2.7 K.
 
Yes, we've never been able to get to 0K. Space is at about 2.7K like Mapes says because of the Cosmic Background Radiation.

The reason we can't get to 0K is because of statistical mechanics, basically.

http://en.wikipedia.org/wiki/0K
 
jaredmt said:
is this possible anywhere?
i know 0 kalvin is the lowest temperature possible that we've been able to attain. but is it possible that in outerspace where there is no heat from sun, that it gets below zero kalvin?

im just curious. I am not sure wether this was "proven" to be the lowest possible temp or just the lowest temp we've been able to get. because i do know that no matter how hard you try to take heat out of something, more heat will just keep going back into it at the same time

Yes, it's possible, in a Laser system, for example.

Temperature can be defined as the partial derivative of energy with respect to entropy; in a system like a Laser, there is "population inversion" so entropy *decreases* instead of increase, when energy increases, so the absolute temperature is negative.
 
As Norman Ramsey has pointed out, objects with negative temperature are not colder than absolute zero, but instead hotter than anything else. Heat energy will always flow from a inversion state to a state that is closer to equilibrium; this is the characteristic of a high temperature, not a low temperature.
 
As lightarrow points out, the statistical-mechanical origin of 'temperature' can lead to counterintuitive results- for example, a population inversion in a two-state system corresponds to negative temperatures.

0 K should be considered a thermodynamic limit.

'0 K' is not acheivable due to the laws of thermodynamics, and it is also not true that 'all motion ceases at 0 K' due to the zero-point energy.
 
ok that is confusing that -k is actually hotter than +k. there are actually mechanical tests where they created a negative temperature? and it was hotter? that's strange
 
jaredmt said:
ok that is confusing that -k is actually hotter than +k. there are actually mechanical tests where they created a negative temperature? and it was hotter? that's strange
Probably better to think of it as a mis-use of the concept of temperature.
There are areas of solid state physics where you treat an electron as having negative mass - the maths works and you get the right answer - but it's not necessarily 'real'.
 
o. so basically we just arent technologically advanced enough to get the right formula to achieve the real -k (if it exists)
 
  • #10
jaredmt said:
o. so basically we just arent technologically advanced enough to get the right formula to achieve the real -k (if it exists)

How did you conclude that from the responses? It's not a technological barrier.
 
  • #11
jaredmt said:
o. so basically we just arent technologically advanced enough to get the right formula to achieve the real -k (if it exists)

No I mean that negative temperature in a laser inversion isn't real it's just a convenient mathematical trick.
It's like being overdrawn at the bank, you don't really own 10 negative dollars - it's just easier to do the sums that way.
 

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