# How might this hypothetical “egg doneness” detector work? **URL:** \ **Category:** Factual Questions\ **Created:** [February 23, 2026, 3:21pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907 "2026-02-23T15:21:37Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Saffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saffer/32/6440_2.png) [@Saffer](https://boards.straightdope.com/u/Saffer)\ **Post date:** [February 23, 2026, 3:21pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/1 "2026-02-23T15:21:37Z")
Let’s say we have an unlimited budget and we don’t care much about practicality, and our goal is to be able to receive an egg, which has been boiled for an unknown duration, and determine its doneness, which I would define as how liquid vs solid the yolk is, without damaging the egg or rendering it inedible. what are are options for building a device or otherwise making this determination? ---
**Author:** ![Dorjan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dorjan/32/12440_2.png) [@Dorjan](https://boards.straightdope.com/u/Dorjan)\ **Post date:** [February 23, 2026, 3:25pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/2 "2026-02-23T15:25:45Z")
Ultrasound is an easy way. ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [February 23, 2026, 3:32pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/3 "2026-02-23T15:32:40Z")
Ultrasound satisfies neither the budgetary nor practicality constraints. You want small angle neutron scattering. > **[Small-angle neutron scattering](https://en.wikipedia.org/wiki/Small-angle_neutron_scattering)** > > Small-angle neutron scattering (SANS) is an experimental technique that uses elastic neutron scattering at small scattering angles to investigate the structure of various substances at a mesoscopic scale of about 1–100 nm. > Small angle neutron scattering is in many respects very similar to small-angle X-ray scattering (SAXS); both techniques are jointly referred to as small-angle scattering (SAS). The most important feature of the SAS method is its potential for analyzing the inner structure of d... ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [February 23, 2026, 5:57pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/4 "2026-02-23T17:57:01Z")
There’s the old “spin the egg” trick. A cooked egg spins but a fresh egg stalls right away. But it doesn’t tell degree of doneness. ---
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [February 23, 2026, 6:00pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/5 "2026-02-23T18:00:18Z")
Might X-ray show opaque vs clear, if the done-cooked portion is not so transparent? ---
**Author:** ![Lucas\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lucas_jackson/32/303_2.png) [@Lucas\_Jackson](https://boards.straightdope.com/u/Lucas_Jackson)\ **Post date:** [February 23, 2026, 6:06pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/6 "2026-02-23T18:06:25Z")
Spin the egg then ever so briefly put your hand on it to stop it. If its boiled (solid) it will stay stopped. If its raw (liquid) it will resume spinning. But as you mentioned, it can’t tell the degree of solidness or liquidness. ---
**Author:** ![echoreply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/echoreply/32/3641_2.png) [@echoreply](https://boards.straightdope.com/u/echoreply)\ **Post date:** [February 23, 2026, 6:08pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/7 "2026-02-23T18:08:06Z")
> [@Saffer](#): > > Let’s say we have an unlimited budget and we don’t care much about practicality, and our goal is to be able to receive an egg, which has been boiled for an unknown duration, and determine its doneness, which I would define as how liquid vs solid the yolk is, without damaging the egg or rendering it inedible. As long as practicality is not an issue, just cut the egg in half and see how done it is. If it is not done to the desired level, discard it and do the same with the next egg until one is found that is cooked the right amount. ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [February 23, 2026, 6:48pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/8 "2026-02-23T18:48:47Z")
> [@Saffer](#): > > Let’s say we have an unlimited budget and we don’t care much about practicality, and our goal is to be able to receive an egg, which has been boiled for an unknown duration, and determine its doneness, which I would define as how liquid vs solid the yolk is, without damaging the egg or rendering it inedible. > > what are are options for building a device or otherwise making this determination? It already exists. > [@Saffer](#): > > Let’s say we have an unlimited budget and we don’t care much about practicality, and our goal is to be able to receive an egg, which has been boiled for an unknown duration, and determine its doneness, which I would define as how liquid vs solid the yolk is, without damaging the egg or rendering it inedible. > > what are are options for building a device or otherwise making this determination? It already exists. Ann Reardon First segment. > **[We Tested TikTok Gadgets – Don’t Buy This One](https://www.youtube.com/watch?v=ft54Xw_OWCk%2F)** > > Testing Gadgets for you. Electric peeler, solar battery and more.With thanks to sponsor: https://resinc.com.au/howtocookthat ask them about the best solar so... ---
**Author:** ![xtenkfarpl](https://avatars.discourse-cdn.com/v4/letter/x/c2a13f/32.png) [@xtenkfarpl](https://boards.straightdope.com/u/xtenkfarpl)\ **Post date:** [February 23, 2026, 7:53pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/9 "2026-02-23T19:53:57Z")
> [@Saffer](#): > > what are are options for building a device or otherwise making this determination? Wouldn’t it be better to have it as a realtime control system rather than testing the egg after the fact? Less wasteful. Lots of ideas. Ultrasound, neutron diffraction. X rays? Terawave scanning? This looks like a prime candidate for the ig Nobels… ---
**Author:** ![abcdefghij](https://avatars.discourse-cdn.com/v4/letter/a/43a26b/32.png) [@abcdefghij](https://boards.straightdope.com/u/abcdefghij)\ **Post date:** [February 23, 2026, 8:25pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/10 "2026-02-23T20:25:24Z")
> [@Velocity](#): > > Might X-ray show opaque vs clear, if the done-cooked portion is not so transparent? Optically transparent and X-ray transparent are not related. X-radiography is sensitive to density, which is probably not much different between raw and cooked. Small-angle X-ray scattering is sensitive to structural changes, but in order not to waste eggs, you’ll want to use the full [USAXS/SAXS/WAXS](https://usaxs.xray.aps.anl.gov/) suite at Argonne National Lab. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [February 24, 2026, 3:12am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/11 "2026-02-24T03:12:28Z")
> [@echoreply](#): > > > [@Saffer](#): > > > > Let’s say we have an unlimited budget and we don’t care much about practicality, and our goal is to be able to receive an egg, which has been boiled for an unknown duration, and determine its doneness, which I would define as how liquid vs solid the yolk is, without damaging the egg or rendering it inedible. > > As long as practicality is not an issue, just cut the egg in half and see how done it is. If it is not done to the desired level, discard it and do the same with the next egg until one is found that is cooked the right amount. I’m going to go out on a limb and suggest that @Saffer is likely to consider cutting an egg in half to comprise “damage”. ---
**Author:** ![Saffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saffer/32/6440_2.png) [@Saffer](https://boards.straightdope.com/u/Saffer)\ **Post date:** [February 24, 2026, 3:26am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/12 "2026-02-24T03:26:37Z")
Indeed ---
**Author:** ![Saffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saffer/32/6440_2.png) [@Saffer](https://boards.straightdope.com/u/Saffer)\ **Post date:** [February 24, 2026, 3:30am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/13 "2026-02-24T03:30:22Z")
Yes. so far the only viable solutions are ultrasound and neutron scattering. ---
**Author:** ![Mangetout](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mangetout/32/19_2.png) [@Mangetout](https://boards.straightdope.com/u/Mangetout)\ **Post date:** [February 24, 2026, 9:36am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/14 "2026-02-24T09:36:37Z")
Whilst this wouldn’t work by hand for partly cooked eggs (pretty sure it’s the white that’s doing most of the work with this trick) - the effect might be so slight for a soft-boiled egg that it would not resume spinning, but a machine that precisely senses the momentum of the contents of an egg by rotating it and stopping could probably be made. ---
**Author:** ![Marvin\_the\_Martian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/marvin_the_martian/32/2898_2.png) [@Marvin\_the\_Martian](https://boards.straightdope.com/u/Marvin_the_Martian)\ **Post date:** [February 24, 2026, 4:39pm UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/15 "2026-02-24T16:39:46Z")
Attach an audio transducer to side of egg. Tap on other side of egg (without breaking shell) using a calibrated striker. Measure response at the transducer - possibly take an FFT or just measure rise and fall times. Frequency response will be a function of viscosity. Compare to empirical data taken from eggs of various degrees of doneness. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [February 25, 2026, 1:50am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/16 "2026-02-25T01:50:21Z")
In other words, egg seismography. Or egg ultrasound. Depending on the nature of the induced sonic impulse. ---
**Author:** ![Mama\_Zappa](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@Mama\_Zappa](https://boards.straightdope.com/u/Mama_Zappa)\ **Post date:** [February 25, 2026, 2:31am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/17 "2026-02-25T02:31:50Z")
Needle sampling. It’s mature technology - every hospital has it for doing breast biopsies and the like. A tiny drill to make a hole in the shell. Take the biopsy….. er, sample. Squirt the sample onto a plate and examine under a microscope or with the naked eye. The main downside would be potential leakage through the needle hole, but that can be made small enough that this would be minimal. ---
**Author:** ![Saffer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/saffer/32/6440_2.png) [@Saffer](https://boards.straightdope.com/u/Saffer)\ **Post date:** [February 25, 2026, 2:43am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/18 "2026-02-25T02:43:49Z")
> [@Marvin\_the\_Martian](#): > > Attach an audio transducer to side of egg. Tap on other side of egg (without breaking shell) using a calibrated striker. Measure response at the transducer - possibly take an FFT or just measure rise and fall times. Frequency response will be a function of viscosity. Compare to empirical data taken from eggs of various degrees of doneness. Bonus point for the detailed instructions! ---
**Author:** ![Shalmanese](https://avatars.discourse-cdn.com/v4/letter/s/45deac/32.png) [@Shalmanese](https://boards.straightdope.com/u/Shalmanese)\ **Post date:** [February 25, 2026, 5:05am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/19 "2026-02-25T05:05:27Z")
> [@Saffer](#): > > Let’s say we have an unlimited budget and we don’t care much about practicality, and our goal is to be able to receive an egg, which has been boiled for an unknown duration, and determine its doneness, which I would define as how liquid vs solid the yolk is, without damaging the egg or rendering it inedible. Place 6 eggs and 6 egg analogues into a pot at the same time (carefully ensuring that the egg and egg analogues are stored together so they start from the same environmental conditions). Starting at 5 minutes, retrieve 1 egg and 1 egg analogue every 30 seconds. Destructively test the egg analogue to gather, with high confidence, what the state of the egg is. You can serve the egg for which the analogue is the closest to your desired doneness. I believe we can bioengineer an egg analogue to have almost indistinguishable behavioral characteristics to a real egg and, with sufficient research, could even get the price down to the cost almost exactly at parity to real eggs. If we were to ever achieve this feat, we could package 6 eggs and 6 egg analogues into cardboard dimpled containers and sell them at the same price as a dozen eggs! ---
**Author:** ![Francis\_Vaughan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/francis_vaughan/32/3093_2.png) [@Francis\_Vaughan](https://boards.straightdope.com/u/Francis_Vaughan)\ **Post date:** [February 25, 2026, 5:25am UTC](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907/20 "2026-02-25T05:25:40Z")
Hmmm. An analogue isn’t totally off the wall. We could construct an egg analogue containing a material that matches the thermal coefficient and conductivity of an egg, and which contains a material that goes transparent at the temperature at which egg protein starts to coagulate. Put it in a transparent shell. Drop it in the water with your real egg. You will see a surface inside the analogue that shrinks as it heats. If the surface shrinks to nothing the egg is likely hard boiled. With some of the apparent analogue contents still visible, you can see how far the transition temperature for cooking protein has travelled into the eg, and can decide on how cooked you want it. This mimics the actual heat transfer and cooking, and probably contains all the information you need. It would even account for cooking in less than boiling point water (or boiling at altitude.) Some sort of phase transition material does the temperature transition, just needs to be reversible. Maybe a change in refractive index, then you mix a dispersion of the materials into the main matrix. When it hits the right temperature, you choose the surrounding matrix such that its refractive index matches, and the thing transitions from milky to clear. A wax that solidifies with a messy structure and is opaque, versus transparent when melted, could also work. A lot of possibilities. We might need two temperature transitions, one for egg white, and another for yolk. [Next page](https://boards.straightdope.com/t/how-might-this-hypothetical-egg-doneness-detector-work/1027907.md?page=2)