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How to boil an egg… the hard way

November 13, 2010

OK, there you are, enjoy your breakfast!


I might explain that a bit more.

This is indeed an egg-cooking formula! The full derivation is here.

where ρ is density, c the specific heat capacity, and K thermal conductivity of ‘egg’.
According to this formula, a medium egg (M~57 g) straight from the fridge (Tegg=4°C) takes four and a half minutes to cook, but the same egg would take three and a half minutes if it had been stored at room temperature (Tegg=21°C). If all the eggs are stored in the fridge, then a small (size 6, 47 g) egg will require four minutes to cook, and a large egg (size 2, 67 g) will take five minutes.

You might understand this. I don’t. I know I think it’s awesome and all – egg derivation, how crazy is that? Yaaaay! …but I don’t understand it.


Luckily for me and all you Norwegians out there, the University in Oslo have used the formula to create a flash animation that calculate the cooking time according to egg circumference, how well you want it cooked, the temperature of the egg and height above sea level.

(screenshot stolen from this interesting article at


The University’s egg calculator is here.

And there you are: now you’re ready to cook eggs, scientific style!

There’s some discussion as to whether it is a good thing to pierce the eggshell at the flat end.  There’s actually been carried out a study on this. Apparently it makes no difference in fresh eggs, but if your eggs are a few days or weeks old, piercing a hole will prevent the eggshell from splitting. The study is from 1973, and I love the way they conclude the abstract:

Housewives should pierce eggs before boiling them, since if they are fresh it will do no harm and if they are stale it will prevent splitting.


For more information about the composition of eggs and the chemistry of cooking them, check out these excellent links:

Towards the perfect soft boiled egg – By Martin Lersch at

The Science of Boiling an Egg by Charles D. H. Williams at the University of Exeter’s home page


Other things you might like to know:

Why egg yolk is yellow by Jonathan D. Blount, David C. Houston and Anders Pape Møller

Which came first, the chicken or the egg? Alice Shirrell Kaswell over at Improbable Research conducted an experiment where she mailed an egg and a chicken, to see which arrived first.

Are organic and/or free range eggs healthier for you? Apparently, there is no difference. There are even indications that free range and organic eggs have a higher content of organic pollutants because there is less control of what the birds eat. (However and of course – free range and/or organic chicken farming remains a more moral and ethical option than cage-chickens.

And since I happen to be an archaeologist: here are some 60.000 years old engraved ostrich eggs. Possibly with some symbolic content. Anyways: pretty.


…and if you want a good laugh, check out The evolution of the egg: A fairytale for grown-ups? at the creationist website Apparently, since eggs can’t think – evolution must be wrong.

Let’s say evolution was responsible for the beginning, and let’s say the egg was the first to evolve (before the chicken). Why did it do that? Why would there be nothing, and over millions of years, nothing became simple organisms, then these organisms became an egg? I can understand that a fish evolved legs and lungs over millions of years–because he (and his necessary female help mate) wanted to breathe, and to walk on dry land. But why would a thoughtless egg appear first and then want to become a chicken? How and why did it evolve with a yolk, a white, and a shell shaped like . . . like and egg?

If the egg was shaped with a rounded point at each end for ease-of-laying (a square egg would be painful), how did evolution know to make it that shape if there were never any chickens in the first place to know that an egg is made to be laid? Another small dilemma. How did the first egg get fertilized to become the first chicken? What or who fertilized it, and why did he fertilize it and sit on it until it hatched? How did the fertilizing creature evolve and have the ability to fertilize an egg that he found. How did he get the seed into the egg to fertilize it? And why did the (rooster) evolve as a bird? Unless he was an egg first, and if so, we have the above questions to deal with, because his egg would also need to be fertilized. Who did the fertilizing?

Evolution certainly is a fairytale for grown-ups.


[darwinian facepalm]

[/darwinian facepalm]

3 Comments leave one →
  1. Tine permalink
    November 29, 2010 5:46 pm

    Gotta love creationists!

  2. Rune permalink
    January 17, 2011 2:22 pm

    Great post. Love the formula, and also the other links. You should post more frequently!

    • January 17, 2011 2:57 pm

      Thank you Rune!
      I have several half-written articles that I am planning to post, but unfortunately my master’s thesis is also half-written… and due soon. So I’m making a few very adult priorities these days. Sigh.

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