[Lewis Thomson (OP)]

Yemi would like to know the answers to this question.

"Can you make hard boiled eggs by simply putting raw eggs inside boiled water off the stove?"

Have you tried this? Share your thoughts in the comments below...

[chiralSPO]

To cook the egg you need to maintain a high temperature for a certain amount of time. In theory, you could bring a large enough pot of water to a boil, turn off the stove and then drop an egg into it, and wait for it to cook.

In practice, this would likely be a very inefficient way of doing it. The water would be cooled down as it transfers heat to the egg, and then the whole system would continue cooling down for the duration of the cooking. So you would probably need a much larger amount of water initially (and heating it to a boil would take more energy) and the amount of excess water would depend on how well insulated the cooking vessel is (I wouldn't recommend trying to heat a thermos over a burner, though you might be able to accomplish this by putting an immersion heater into a thermos of water....), and how long you are willing to wait for the egg to cook.

[Bored chemist]

It is a reasonable  hypothesis that among the reasons why someone invented the stove was to make it easier to boil eggs.

[evan_au]

Arrhenius discovered a relationship that, for many common chemical reactions, the rate of the reaction roughly doubles for every 6C rise in temperature.
- If you want your egg to cook twice as fast, put it in a pressure cooker, and heat it to 106C
- But as soon as you turn the heat off your boiling water, it starts to cool down from 100C. By the time it has dropped to 94C, the cooking time has doubled. By the time it reaches 88C, the cooking time is 4x longer.
- With a normal saucepan of boiling water in a kitchen at 25C, it might take an hour to hard-boil your egg - but highly variable!
- Whether you leave the lid on or off will make a dramatic difference to the cooking time.

See: https://en.wikipedia.org/wiki/Arrhenius_equation

PS: If you want to save energy, or speed up the cooking time, do not put an egg in the microwave. It rapidly disassembles itself all through the microwave, like a miniature hand-grenade.

[alancalverd]

In my youth, the second year Advanced Theoretical Physics lecture course spent an entire term boiling an egg  on the blackboard. Assuming a constant external temperature, derive the heat diffusion equations across three boundary membranes and through two media with a single phase change in each. It's one hell of a lot of simultaneous differential equations, even for a spherical egg.

The general solution has huge implications in industry, astrophysics, physiology.....and even, it turned out, in radiation measurement. And best of all, if your answer turns out to be 6 minutes (starting with 100 deg C on the outside and 15 deg C throughout the inside, for a medium chicken egg) you can verify it by experiment!

Meanwhile in the biochemistry class, they learned that just maintaining it at around 30 deg C for a few years will produce a solid egg, as discovered by Chinese cooks thousands of years ago.

[Bored chemist]

the rate of the reaction roughly doubles for every 6C rise in temperature.
- If you want your egg to cook twice as fast, put it in a pressure cooker, and heat it to 106C
- But as soon as you turn the heat off your boiling water, it starts to cool down from 100C. By the time it has dropped to 94C, the cooking time has doubled. By the time it reaches 88C, the cooking time is 4x longer.

Interesting
100C will cook an egg in about 4 minutes
Lets see how that pans out.
temp   min   hrs
100     4   0.066666667
94     8   0.133333333
88    16   0.266666667
82   32   0.533333333
76   64   1.066666667
70   128   2.133333333
64   256   4.266666667
58   512   8.533333333
52   1024   17.06666667
46   2048   34.13333333
40   4096   68.26666667
OK so, tucked under a hen at 40C the egg will be cooked in a little under 3 days. That's bad news since it takes about 3 weeks to hatch.

Thing about that equation- it doesn't reliably give the right answer if there are other things going on.

More realistically, we need to consider what's actually happening.
If you drop an egg into boiling water, without its shell,  it cooks a lot quicker. Pretty much as soon as it gets to about 60C
The actual "cooking" reaction is very fast.
What takes 4 minutes is for the heat to penetrate the egg. And that's not subject to Arrhenius behaviour.

[wolfekeeper]

The cooking time depends on the temperature, low temperatures take a LOT longer. Commercially eggs are pasteurised for an hour and a quarter at 58C to sterilise them.

You can't actually cook an egg below 55.5C because common food poisoning bacteria (nevermind extremophiles) multiply quicker than they die from the heat, but otherwise the table above is roughly right.

A big pan full of boiled water will certainly cook an egg long before the pan cools.

Me, I don't use a pan I steam my eggs using an electric steamer for just over 6 minutes, and then I run them under a cold tap. The air sac collapses, and peels them inside the shell. Much faster and much more efficient and I get a perfect peeled soft boiled egg.

Amusingly, the whites and the yolks cook at different temperatures and rates. There's an online calculator where you can set the 'doneness' of the white and yolk independently and with extreme care it's possible to cook the yolk and fail to solidify the white (it's relatively easy to do it the other way around), if you're into that kind of thing and you're prepared to wait an entire day for it:

https://www.chefsteps.com/activities/the-egg-calculator

[Bored chemist]

You can't actually cook an egg below 55.5C because common food poisoning bacteria (nevermind extremophiles) multiply quicker than they die from the heat, but otherwise the table above is roughly right.

Cooking is not really about killing bacteria.
You can't cook eggs below about 60C because the egg white protein is stable up to that temperature.
https://cdn.intechopen.com/pdfs/39928/InTech-Effect_of_heat_on_egg_white_proteins.pdf

The table is plainly wrong; Hens do not cook eggs; that was my point.

[chiralSPO]

The rate of reaction approximation only applies when the reaction is favorable (ΔG <0). In these cases, the rate of reaction is often proportional to e^–E_A/RT (where E_A is the activation energy per mole, R is the universal gas constant, and T is the temperature in Kelvin; one could also calculate using the E^A on a per molecule basis and substitute Boltzmann's constant, k_B, for R).

In these cases, because the rate is exponentially related to the inverse of the temperature, the scaling of rate with addition of temperature makes sense.

However, ΔG is also a function of temperature (ΔG = ΔH – TΔS), so changing T too much when reactions involve a significant ΔS, could well make a reaction favorable or disfavorable. (the rate at which water freezes is NOT faster at 2 °°C than at –2°C, for hopefully obvious reasons)

[wolfekeeper]

You can't actually cook an egg below 55.5C because common food poisoning bacteria (nevermind extremophiles) multiply quicker than they die from the heat, but otherwise the table above is roughly right.

Cooking is not really about killing bacteria.

On the contrary, it mostly is. Not dying of food poisoning is very popular!

[alancalverd]

I digress.

[Bored chemist]

You can't actually cook an egg below 55.5C because common food poisoning bacteria (nevermind extremophiles) multiply quicker than they die from the heat, but otherwise the table above is roughly right.

Cooking is not really about killing bacteria.

On the contrary, it mostly is. Not dying of food poisoning is very popular!

Only humans cook food (afaik)
Our digestive systems are not very different from those of other animals.
The other animals survive.
So cooking isn't a big feature in survival.

[alancalverd]

Our digestive systems are not very different from those of other animals.

The problem is that we are weak omnivores derived from specialist apes. Our cousins live at low population densities in food-rich tropical forests where they have evolved alongside their favorite foods which are available year-round. Moving away from this benign environment we have had to make all sorts of vegetables digestible and even get protein from animal sources (principally herbivores, with a very different gut) to sustain a dense population in a temperate or arctic climate, and this seems to demand cooking.

[FannieMaloy]

I put cold water in the pot and place the eggs on the bottom (some space in between), turn the stove on without a cover over the pot. The water level is usually about an inch above the top of the eggs. When the water starts to boil, move the pot away from the heat and put a cover on it for 12 minutes. Peel and enjoy perfectly hard boiled eggs.