# Physical limits on heat? **URL:** \ **Category:** Factual Questions\ **Created:** [June 14, 2024, 4:49pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882 "2024-06-14T16:49:53Z")\ **Posts on this page:** 11\ **Page:** 2
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 18, 2024, 8:20pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/21 "2024-06-18T20:20:13Z")
Which means that the zero-temperature approximation works very well for it. As with all neutron stars, the thermal energy, high though it might seem by our standards, is still negligible compared to the Fermi energy. ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [June 18, 2024, 8:24pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/22 "2024-06-18T20:24:00Z")
I’m finding the following to be a surprisingly difficult question to get an answer to on the internet: what is the estimated electron-volt energy of a magnetic monopole presuming they exist? Or rather, what’s the lower limit on what their energy could be? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 18, 2024, 8:34pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/23 "2024-06-18T20:34:29Z")
The lower limit on the monopole’s mass is somewhat higher than the energy produced by the LHC. I say “somewhat higher”, because if it were only a little higher, then we’d probably see some effects start to show up in electromagnetic interactions from virtual monopoles. The upper limit on the monopole’s mass is the same as its charge, in appropriate units, because if no other sorts of monopoles exist, then they at least exist as extreme Reissner-Nordstrom black holes. As my advisor used to say, we know for sure that monopoles exist. There just might be a very low number of them, like zero. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [July 12, 2024, 2:03pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/24 "2024-07-12T14:03:02Z")
Another thought on limits on temperature – a framing, perhaps: In most areas of technology, science, engineering, and human activity, we concern ourselves with temperatures confined to just one order of magnitude. Most of us have nothing to do with temperatures colder than 250 K, or warmer than 2500 K. For example, there are vanishingly few engineering materials that can operate above 2500 K, and none above 4000 K. There are exceptions of course, like the entire field of cryogenics. But the people who have experiences in these fields are a pretty small minority. I’m not thinking of another physical variable that spans such a small dynamic range in our typical experience. ---
**Author:** ![Pleonast](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pleonast/32/1183_2.png) [@Pleonast](https://boards.straightdope.com/u/Pleonast)\ **Post date:** [July 12, 2024, 2:28pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/25 "2024-07-12T14:28:51Z")
> [@Napier](#): > > I’m not thinking of another physical variable that spans such a small dynamic range in our typical experience. Maybe pressure? Just like the ambient temperature biases our experience, the ambient pressure does as well. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 12, 2024, 2:37pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/26 "2024-07-12T14:37:41Z")
A person wearing high-heel shoes can exert pressures over a hundred times atmospheric pressure, and another order of magnitude or two either way isn’t all that exotic. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [July 12, 2024, 7:20pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/27 "2024-07-12T19:20:27Z")
> [@Pleonast](#): > > Maybe pressure? A propeller-shaped fan might generate as little as 0.002 psi. Hydraulic power, for example a log splitter or a bottle jack or a backhoe, typically operates at something like 2000 psi, as do many pressure washers. That’s six orders of magnitude, for some commonly experienced pressures. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 12, 2024, 7:43pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/28 "2024-07-12T19:43:55Z")
If we confine ourselves to solids, density has a fairly narrow range. Ice is roughly at the bottom at 1 g/cc, and gold at the top at 20 g/cc. You can stretch this a little further with exotic materials like pure lithium (0.5 g/cc) and osmium (22 g/cc), but it isn’t much. Of course, gases are much less dense, not to mention vacuum. Your call as to whether it’s reasonable to exclude them. But there is a curiously large gap between the densest gases and the lightest solids (or even liquids) at ordinary pressures. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 12, 2024, 7:46pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/29 "2024-07-12T19:46:54Z")
> [@Napier](#): > > A propeller-shaped fan might generate as little as 0.002 psi. That’s a pressure difference. Temperature differences can also be arbitrarily small. Most folks in their everyday life don’t encounter an absolute pressure much less than atmospheric. And yeah, @Dr.Strangelove , I thought of densities, as well, but I don’t think it’s reasonable to exclude gases, which means that four orders of magnitude (from air to lead) isn’t difficult. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [July 12, 2024, 7:51pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/30 "2024-07-12T19:51:07Z")
Do we get to exclude the negative temperatures inside a laser pointer, though? ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [July 12, 2024, 9:41pm UTC](https://boards.straightdope.com/t/physical-limits-on-heat/1002882/31 "2024-07-12T21:41:45Z")
> [@Chronos](#): > > That’s a pressure difference. Temperature differences can also be arbitrarily small. Most folks in their everyday life don’t encounter an absolute pressure much less than atmospheric. True! Point taken! [Previous page](https://boards.straightdope.com/t/physical-limits-on-heat/1002882.md?page=1)