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> LEGO employs some professionals who no doubt devote their career to understanding many things about LEGO That is not limited to LEGO: Some researchers from L

> LEGO employs some professionals who no doubt devote their career to understanding many things about LEGO That is not limited to LEGO: Some researchers from Lancaster University also were researching LEGO bricks (read: Playing around trying to set record-low temperatures for LEGO bricks); and found out they're excellent insulators at sub-kelvin temperatures: https://news.ycombinator.com/item?id=21884755 https://news.ycombinator.com/item?id=21884755

Ruthalas 5y ago
Out of curiosity, what is a "sub-Kelvin" temperature? As an absolute scale, isn't it impossible to be off the bottom of that scale?
- detaro 5y ago
  a temperature below 1 Kelvin.
  - Ruthalas 5y ago
    Ah, thank you!
azalemeth 5y ago
I have personally put lego bricks in 12T magnetic fields, embedded them in agar, accidentally irradiated them with 94 GHz microwaves, and blasted them with a lot of RF. Some of my friends have irradiated them (accidentally) at the diamond light source x-ray synchrotron, which can deliver MGy doses in a short period of time. Still others have used them as coarse positioning blocks on high end (read: homebuilt) novel forms of microscopes or other high-end optical equipment. They're fantastic for prototyping stuff quickly, or, in a pinch, acting as a dimensional reference. (Yes, really!) You can put them in a vacuum. They don't degas much. They're magnet safe and can survive being in really high EM fields. They've got a high melting point. They don't become too brittle at sub-K temperatures. Blocks continue to mate as temperature varies -- Lego's process is fantastic at minimising temperature variation. They're really quite radiation resistant (many plastics fail horribly if you shoot them with >1 kGy). A child (or student!) can make a symmetric structure with them given a vague sketch design. A single "1x" wide Technik piece has a persistence length of about 80 cm. Structures you can build with lego are therefore really remarkably strong. Every lego is made to insanely tight tolerances to published, well-known dimensions, and, best of all, if they break (an achievement!) you can buy another one for absolutely nothing in science-money terms. (The finance dept. look at you a bit weird when you put fifteen copies of "Spaceman playset" on an expenses claim form though). I frankly think that most experimentalists somewhere in their life have some lego. (I have a "Lego MRI" set that is only available to professionals!)
- Twixes 5y ago
  Out of curiosity, how do irradiated plastics fail? Do they become brittle, soft, something else?
  - azalemeth 5y ago
    The details are really, really complex, but either (a) they heat up from the absorbed dose (1 Gy is 1 kJ / kg) or (b) high gamma fluxes ionise CH bonds and cross link randomly, leading (typically) to brittle failure modes. Sometimes with heating you get spallation. The accelerator I most recently used has a large set of house-grade UPVC glass windows around the target stage to help thermally control it (it's variable temperature). It's after the beam dump and behind quite a lot of lead, but they've been there for a while. The glass is a weird shade of purple in a pretty gaussian pattern and the formerly bright-white UPVC is brown in places, purple in other places, and looks a bit like wood does when it's rotting and peeling off. If you hit it with a hammer I'm sure it would disintegrate. There are rad hard plastics but again it's all a function of "what radiation", "what energy", "how much" and "how long" and you end up doing monte carlo simulations pretty quickly.
- HWR_14 5y ago
  I recently read that LEGO bricks put under compression (aligned with the studs in a standard 2x2) will liquify from the pressure before they break. Do you know if that's true?

Ruthalas 5y ago

Out of curiosity, what is a "sub-Kelvin" temperature? As an absolute scale, isn't it impossible to be off the bottom of that scale?

detaro 5y ago
a temperature below 1 Kelvin.
- Ruthalas 5y ago
  Ah, thank you!

azalemeth 5y ago

I have personally put lego bricks in 12T magnetic fields, embedded them in agar, accidentally irradiated them with 94 GHz microwaves, and blasted them with a lot of RF. Some of my friends have irradiated them (accidentally) at the diamond light source x-ray synchrotron, which can deliver MGy doses in a short period of time. Still others have used them as coarse positioning blocks on high end (read: homebuilt) novel forms of microscopes or other high-end optical equipment. They're fantastic for prototyping stuff quickly, or, in a pinch, acting as a dimensional reference. (Yes, really!) You can put them in a vacuum. They don't degas much. They're magnet safe and can survive being in really high EM fields. They've got a high melting point. They don't become too brittle at sub-K temperatures. Blocks continue to mate as temperature varies -- Lego's process is fantastic at minimising temperature variation. They're really quite radiation resistant (many plastics fail horribly if you shoot them with >1 kGy). A child (or student!) can make a symmetric structure with them given a vague sketch design. A single "1x" wide Technik piece has a persistence length of about 80 cm. Structures you can build with lego are therefore really remarkably strong. Every lego is made to insanely tight tolerances to published, well-known dimensions, and, best of all, if they break (an achievement!) you can buy another one for absolutely nothing in science-money terms. (The finance dept. look at you a bit weird when you put fifteen copies of "Spaceman playset" on an expenses claim form though). I frankly think that most experimentalists somewhere in their life have some lego. (I have a "Lego MRI" set that is only available to professionals!)

Twixes 5y ago
Out of curiosity, how do irradiated plastics fail? Do they become brittle, soft, something else?
- azalemeth 5y ago
  The details are really, really complex, but either (a) they heat up from the absorbed dose (1 Gy is 1 kJ / kg) or (b) high gamma fluxes ionise CH bonds and cross link randomly, leading (typically) to brittle failure modes. Sometimes with heating you get spallation. The accelerator I most recently used has a large set of house-grade UPVC glass windows around the target stage to help thermally control it (it's variable temperature). It's after the beam dump and behind quite a lot of lead, but they've been there for a while. The glass is a weird shade of purple in a pretty gaussian pattern and the formerly bright-white UPVC is brown in places, purple in other places, and looks a bit like wood does when it's rotting and peeling off. If you hit it with a hammer I'm sure it would disintegrate. There are rad hard plastics but again it's all a function of "what radiation", "what energy", "how much" and "how long" and you end up doing monte carlo simulations pretty quickly.
HWR_14 5y ago
I recently read that LEGO bricks put under compression (aligned with the studs in a standard 2x2) will liquify from the pressure before they break. Do you know if that's true?