Absolute hot
Absolute hot is a theoretical upper limit to the thermodynamic temperature scale, conceived as an opposite to absolute zero.
Planck temperature
Some speculate that the highest possible temperature is the Planck temperature, 1.416784(16)×1032 K.[1][2] There is no existing scientific theory for the behavior of matter at these energies; a quantum theory of gravity would be required.[3] The models of the origin of the universe based on the Big Bang theory assume that the universe passed through this temperature about 10−43 s (one Planck time) after the Big Bang as a result of enormous entropy expansion.[2]
Hagedorn temperature
Another theory of absolute hot is based on the Hagedorn temperature,[4] where the thermal energies of the particles exceed the mass–energy of a hadron particle–antiparticle pair. Instead of temperature rising, at the Hagedorn temperature more and heavier particles are produced by pair production, thus preventing effective further heating, given that only hadrons are produced. However, further heating is possible (with pressure) if the matter undergoes a phase change into a quark–gluon plasma.[5] Therefore, this temperature is more akin to a boiling point rather than an insurmountable barrier. For hadrons, the Hagedorn temperature is 2×1012 K, which has been reached and exceeded in LHC and RHIC experiments.
In string theory, a separate Hagedorn temperature can be defined, where strings similarly provide the extra degrees of freedom. However, it is so high (1030 K) that no current or foreseeable experiment can reach it.[6]
See also
- Absolute zero
- International Temperature Scale of 1990
- Negative temperature, as hotter than positive temperature
- Quark–gluon plasma
- Orders of magnitude (temperature)
- QCD matter
References
- ↑ "2018 CODATA Value: Planck temperature". The NIST Reference on Constants, Units, and Uncertainty. NIST. 20 May 2019. Retrieved 2019-05-20.
- ↑ 2.0 2.1 Tyson, Peter (2007). "Absolute Hot: Is there an opposite to absolute zero?". PBS.org. Archived from the original on 6 August 2009. Retrieved 2009-08-11. Unknown parameter
|url-status=ignored (help) - ↑ Hubert Reeves (1991). The Hour of Our Delight. W. H. Freeman Company. p. 117. ISBN 978-0-7167-2220-5.
The point at which our physical theories run into most serious difficulties is that where matter reaches a temperature of approximately 1032 degrees, also known as Planck's temperature. The extreme density of radiation emitted at this temperature creates a disproportionately intense field of gravity. To go even farther back, a quantum theory of gravity would be necessary, but such a theory has yet to be written.
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- ↑ Absolute Hot. NOVA.
- ↑ Satz, Helmut (1981). Statistical mechanics of quarks and hadrons, International Symposium on Statistical Mechanics of Quarks and Hadrons, 24–31 Aug 1980, Bielefeld, Germany. Amsterdam: North-Holland. ISBN 0-444-86227-7. Search this book on
- ↑ Atick, Joseph J.; Witten, Edward (1988). "The Hagedorn transition and the number of degrees of freedom of string theory". Nuclear Physics B. 310 (2): 291–334. Bibcode:1988NuPhB.310..291A. doi:10.1016/0550-3213(88)90151-4.
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