Planck Temperature: Is It The Upper Limit?

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    Planck Temperature
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Discussion Overview

The discussion centers on the concept of temperature, specifically whether there is an upper limit to temperature and if the Planck temperature serves as that limit. Participants explore theoretical implications of temperature in relation to kinetic energy, the nature of forces at extreme temperatures, and the significance of the Planck temperature in cosmology.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Exploratory

Main Points Raised

  • Some participants question whether the Planck temperature is indeed an upper limit on temperature, suggesting that energy can continually be added to a system to increase its temperature.
  • Others clarify that temperature is a measure of average kinetic energy of particles, implying that the question may be reframed as one about kinetic energy limits.
  • One participant asserts that the Planck temperature is significant as it represents a theoretical limit of quantum mechanics and is associated with phenomena such as black hole evaporation and the early universe.
  • A later reply raises questions about the unification of forces at high temperatures, specifically whether there is a theoretical temperature at which the four fundamental forces combine, and if this is related to the Planck temperature.

Areas of Agreement / Disagreement

Participants express differing views on whether the Planck temperature is an upper limit on temperature, with some asserting it is while others argue against this notion. The discussion remains unresolved regarding the relationship between temperature and the unification of forces.

Contextual Notes

There are limitations in the discussion regarding the definitions of temperature and energy, as well as the assumptions underlying the claims about the Planck temperature and the unification of forces.

flotsam
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Is there an upper limit on temperature? Is the 'Planck temperature' the upper limt?
 
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I don't think so. You can keep piling more and more energy into a system and it will raise its temperature further and further.

There is a theoretical lower limit on temperature though. That is absolute zero, when no particles move at all.

I was going to mention phonons here too, but are they strictly more to do with vibration than temperature, considering vibration and temperature are fairly interchangeable concepts?
 
Temperature is not a measure of energy in general. It is a measure of the average kinetic energy of particles in a given location.

So you're really asking whether there is an upper limit on kinetic energy, and whether this is called the Planck temperature.

The answer is yes, and yes.

Here is the Wikipedia entry, which covers it pretty neatly:

===

The Planck temperature, named after German physicist Max Planck, is the natural unit of temperature, denoted by Tp. The Planck units, in general, represent limits of quantum mechanics. Talking about anything being "hotter" than the Planck temperature doesn't make a lot of sense; it is the temperature at which black holes are theorized to evaporate and the temperature at which the Universe "started" and cooled down from there, according to current cosmology. It is difficult to imagine anything being hotter than the Big Bang.

Tp = Mp/k = square root of (hc^5/Gk^2) = 1.41679 × 10^32 K

where:

Mp is the Planck mass

c is the speed of light in a vacuum

h is the Reduced Planck constant (or Dirac's constant)

k is the Boltzmann constant

G is the gravitational constant
 
Hooloovoo said:
Temperature is not a measure of energy in general. It is a measure of the average kinetic energy of particles in a given location.
So you're really asking whether there is an upper limit on kinetic energy, and whether this is called the Planck temperature.
The answer is yes, and yes.
Here is the Wikipedia entry, which covers it pretty neatly:
===
The Planck temperature, named after German physicist Max Planck, is the natural unit of temperature, denoted by Tp. The Planck units, in general, represent limits of quantum mechanics. Talking about anything being "hotter" than the Planck temperature doesn't make a lot of sense; it is the temperature at which black holes are theorized to evaporate and the temperature at which the Universe "started" and cooled down from there, according to current cosmology. It is difficult to imagine anything being hotter than the Big Bang.
Tp = Mp/k = square root of (hc^5/Gk^2) = 1.41679 × 10^32 K
where:
Mp is the Planck mass
c is the speed of light in a vacuum
h is the Reduced Planck constant (or Dirac's constant)
k is the Boltzmann constant
G is the gravitational constant


Thanks for the reply.
What I now wonder is; how near to this temperature do the 4 forces (gravitation, electro-magnetism, weak and strong nuclear) combine to manifest themselves as one force? Is there any actual theoretical temperature at which this occurs? Is it the Planck temperature? Do you think there could be anywhere so hostile (theoretical or not) in the universe that in that place there is only one force?
 

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