I'm working on a version of wormhole-based FTL travel, and one of the side effects of passing through the wormhole is going to be instantaneous heating of every molecule of the thing passing through. The heating works by dumping a specific amount of thermal energy into every molecule of the object passing through the wormhole, and the rise in temperature is thus affected by the specific heat capacity of each molecule.

However, this instantaneous increase in temperature brings up potential issues of survivability for a human being going through the wormhole. The heating itself exists for reasons related to thermodynamics, but its magnitude is completely up to what's best for the story. I'd like to make the heating survivable for human beings, but also significant enough to be worth a mention in the text. Essentially, I'm shooting for a temperature rise that will be uncomfortable or ideally temporarily debilitating, but not lethal. I realize there's not going to be a ton of data on spontaneous and evenly distributed temperature rise throughout the human body, but any existing and relevant data that can be extrapolated from would be great. Additionally, if this kind of temperature rise would be dangerous for electronics or any other sensitive equipment one might find on a spacecraft, you get bonus points for mentioning that in your answer.

So, to summarize, how much heat could you dump into a person's body before that person reaches the point of suffering significant long-term effects?

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    $\begingroup$ hyperpyrexia starts at a body temperature of 106.1°F or 41.1°C, that is the temprature range at which a persons physical health starts to be seriously impacted if they don't act to lower it.. Above 111.2 °F death is likely. ncbi.nlm.nih.gov/pubmed/11476402 $\endgroup$ – John Oct 28 '19 at 3:27
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    $\begingroup$ @John, is that for a sustained temperature, or a temperature that immediately begins to drop to normal levels? This is a rather odd scenario. Additionally, there may be various parts of the body that aren't normally as affected by rises in body temperature that will be here (e.g., brain, reproductive organs for males, etc.) $\endgroup$ – Gryphon Oct 28 '19 at 3:28
  • $\begingroup$ The body won't cool very quickly if the person does not act, they bodies passive systems is insufficient once you get to the higher temperatures. The problem with answering your question specifically is it impossible thus there is no real world comparison. There is no way to heat a body in any way even close to what you describe so the effects are unknown, so you can use whatever you want within that range. $\endgroup$ – John Oct 28 '19 at 3:33
  • $\begingroup$ Instantaneous infusions of heat to every molecule would increase the volume and therefore pressure of blood gasses as well as gasses in the digestive tract, sinuses etc. resulting in aerobullosis or the bends, as well as sinus pressure, flatulence, and belching. Sudden increases in bodily gas pressures would be quite painful. $\endgroup$ – Ixion Oct 28 '19 at 14:28
  • $\begingroup$ @Ixion Then write up an answer explaining what kind of limits that puts on it ;) $\endgroup$ – Gryphon Oct 28 '19 at 14:29

It looks like there will be only a narrow margin of temperature rise before harm is done to persons passing through a wormhole. Probably, no more than one or two degrees centigrade.

The general conditions associated with heatstroke are as follows:

Heat-related illnesses typically are categorized as heat exhaustion or heatstroke. Heatstroke is divided further into classic and exertional forms. Classic heatstroke is caused by environmental exposure and results in core hyperthermia above 40°C (104°F). This condition primarily occurs in the elderly and those with chronic illness. Classic heatstroke can develop slowly over several days and can present with minimally elevated core temperatures. It is associated with central nervous system dysfunction including delirium, convulsions, and coma, making it difficult to distinguish from sepsis. These manifestations are thought to be an encephalopathic response to a systemic inflammatory cascade.

In their milder forms, heat illnesses are known as heat exhaustion. This will be extremely uncomfortable, but survivable.

Heat exhaustion is a more common and less extreme manifestation of heat-related illness in which the core temperature is between 37°C (98.6°F) and 40°C. Symptoms of heat exhaustion are milder than those of heatstroke and include dizziness, thirst, weakness, headache, and malaise. Patients with heat exhaustion lack the profound central nervous system derangement found in those with heatstroke. Their symptoms typically resolve promptly with proper hydration and cooling.

What makes the survivability of elated temperatures difficult to is the combination of the temperature elevation itself and the duration of the rise.

The term thermal maximum was developed to measure the magnitude and duration of heat that cells can encounter before becoming damaged. Human thermal maximum has been established as a core body temperature of approximately 42°C (107.6°F) for between 45 minutes and eight hours. Cellular destruction occurs more quickly and completely at higher temperatures. Inflammatory factors are released and gastrointestinal permeability increases, which may allow endotoxins into the circulation.16 Hematologic and endothelial changes resembling disseminated intervascular coagulation also occur.

This suggests the limits of the temperature increase will be, at best, one to two centigrade. An almost instantaneous whole-body temperature would be extremely difficult to lower. This will increase the damage caused by the duration of the temperature rise. best to keep it as low as reasonably possible. Expect an immediate onset of elevated temperature to be disorienting and quite likely disabling.


Management of Heatstroke and Heat Exhaustion

JAMES L. GLAZER, M.D., Maine Medical Center, Portland, Maine

Am Fam Physician. 2005 Jun 1;71(11):2133-2140.

URL to above article: American Family Physician, Jun 1, 2005 issue

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    $\begingroup$ Is it possible that artificially giving people hypothermia before passing through the wormhole might increase the possible margin? $\endgroup$ – Gryphon Oct 28 '19 at 6:07
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    $\begingroup$ Typical heat capacity of flesh is about 1500 J/(kg*C). At worst case temperature rise is about 3 C - 4.5 kJ/Kg requiered. Thats is a lot : steel parts of a cabin would rise there temperature by 27C (from say 25C to ~50C), alumininim parts by 150C (you may bake cakes!), copper (wires) by 1000 C - they would melt and cause fires. So its not for humans you shoild wary about! $\endgroup$ – ksbes Oct 28 '19 at 9:07
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    $\begingroup$ @ksbes Where did you get that number for the specific heat capacity of flesh? The figure I found is about 3.5 kJ/(kg*C), more than double the figure you quoted. According to my math skills, that means that copper, with a specific heat capacity of about 0.385 kJ/(kg*C), would experience a heat rise of about 9 times greater than flesh, which makes me wonder where your 1000 C rise number comes from. $\endgroup$ – Gryphon Oct 28 '19 at 10:44
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    $\begingroup$ *temperature rise about 9 times greater than flesh $\endgroup$ – Gryphon Oct 28 '19 at 10:51
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    $\begingroup$ It's from a old cookbook I have. It's a thermal capacity for beef stake. It might be wrong to use it for live flesh... In any case it just makes sitation worse: low-heat capacity materals (like all metals) would be the weak point of this travels. $\endgroup$ – ksbes Oct 28 '19 at 10:53

Very simple answer: 2°F.

An increase in body temperature of two degrees Fahrenheit can affect mental functioning. A five degree Fahrenheit increase can result in serious illness or death.

When your astronauts increase by one degree they will feel it. At 2 degrees all but the most elite and fit individuals will start making mistakes.

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Thus far, the two current & excellent answers focus on biological heating over a biological span of time. Indeed, if a human suffers hyperthermia for an extended period of time, said human will eventually suffer terrible effects and eventually die.

However, your query asks about a process called "flash heating". You don't specify what this entails, except that it is "instantaneous" so I would make an assumption about the process: namely, the time factor involved is so short that, quite literally, the molecules of the person in question don't have enough time to accumulate the heat being input.

For example, it's a common experience in North America (and maybe northern Europe too) that when one enters a supermarket or other public building from a cold or frigid exterior that one passes under a blast heater. This is a device attached to the entryway transom that directs a thin curtain of super-heated air downward as the patron enters. This forms a "curtain of hot air" that acts as an insulation barrier while the physical door is open. If you pass through the doorway quickly, you feel the warm momentarily but never become affected by it. If you stand under the blast heater, you'll eventually warm up, become uncomfortably warm, begin to sweat and etc.

I'd posit that your wormhole technology might be similar. So long as your humans pass through the wormhole quickly, they feel a momentary warmth but are not subjected to the blast long enough for adverse physiological effects to take hold.

Another example: I have successfully passed my hands through the scorching flame of a propane torch on several occasions. The fire is about 36oo deg (2000 degrees centipede). If I left my hand in the flame, it would, just like the starship crew hanging around inside the wormhole, be burnt to a crisp. I'm not burned because my hand isn't in contact with the flame long enough.


I don't think your starship crew will have enough time to be adversely affected. Obviously, if they remain in contact with the heat and said heat can not be instantaneously dissipated again, they will die. It doesn't take many degrees of heat or a very long time for deleterious effects to take hold.

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  • $\begingroup$ I'm not sure that you've properly understood the question. The heat isn't somehow removed immediately after being applied. The humans in question are heated (not by contact with a hot object, but by a quasi-magical effect), and remain at that temperature until cooled by the means that normally cool things. $\endgroup$ – Gryphon Oct 31 '19 at 5:19
  • $\begingroup$ @Gryphon-ReinstateMonica -- Could be! It does specify a "flash" process, an "instantaneous" heating. That reads to me as if the heat is not maintained. Obviously, if it's maintained then survivability goes out the porthole. It's already been established that humans can only tolerate a relatively low high temperature for any length of time. If the quasi magical effect can instantaneously heat a human, then it can also instantaneously remove that heat. It will remain for the OP to qualify. They want it to be survivable --- that means the system can't remain at the high temperature for long! $\endgroup$ – elemtilas Nov 1 '19 at 1:42

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