7 ms·

The Lava Lamp Just Won't Quit

deleted 12y ago
[deleted]
bostik 12y ago
I remember, at the turn of the millennium, when lava lamps were actually used to produce entropy. An SGI project called lavarand had a battery of the things bubbling up and down, used low-end digital cameras to capture images and, after some postprocessing, hashed the results to get what was effectively a fairly good PRNG. [0]http://en.wikipedia.org/wiki/Lavarand http://en.wikipedia.org/wiki/Lavarand
- baddox 12y ago
  Would that be considered a PRNG? I always thought that PRNG implied a completely deterministic sequence based on a relatively simple seed.
  - tonysuper 12y ago
    Technically, a lava lamp is deterministic. Still, I'd say that it's "close enough" to be considered a real RNG. There's almost no way to see a pattern in it, and I'm pretty sure that it would be completely impractical to simulate the contents inside, even if you knew all the initial conditions.
    - baddox 12y ago
      Yeah, I meant "deterministic" as in "generated using standard computations starting from a simple seed." Whether the lava lamp itself is deterministic, or the Universe moreover, is another issue.
    - PhantomGremlin 12y ago
      > Technically, a lava lamp is deterministic. Technically, it's only "deterministic" if you can fully establish the initial state. That's not possible, if for no other reason than the Uncertainty Principle [1] prevents you from measuring the initial conditions carefully enough. Plus you're not really dealing with a closed system, so basically the entire Universe can influence your system going forward. Chaos theory [2] says that you're fighting a losing game if you think it's deterministic. [1] http://en.wikipedia.org/wiki/Uncertainty_principle http://en.wikipedia.org/wiki/Uncertainty_principle [2] http://en.wikipedia.org/wiki/Chaos_theory http://en.wikipedia.org/wiki/Chaos_theory
      - sopooneo 12y ago
        Even if you could determine the initial state, wouldn't quantum effects, aggregating over time, make it non-deterministic?
        PhantomGremlin 12y ago
        That's a really good question. I'd love to hear the answer from a physicist in the know. Assume you could overcome the uncertainty principle or observer effect and you could fully determine the initial conditions of the entire system. You knew the position and momentum of every atom. You knew the spin of every electron. Etc. Etc. Etc. Doesn't the inherent nature of quantum mechanics say that it's still impossible to predict the state of that system at some future time? Interactions only occur probabilistically, and there is no way to predict them a priori.
        rprospero 12y ago
        Physicist here. In terms of predicting the "future state", it depends on what you want to call the "state". If I know the complete wave function of the system, then knowing the wave function at a future point in time is trivial. Just apply the time evolution operator. However, knowing the wave function at a given point in time doesn't tell me the position or momentum - it just tells me the probability with which I'll measure a given position or momentum. So knowing the "state" still means that my measurements will have random components. On a slightly different note, when you talk about knowing the exact position and momentum of every particle, you're not talking about overcoming a physical limitation, but a mathematical one. To put it differently, if I know that the momentum is exactly zero, I do know that the position is. The problem is that the position is NaN. If the position isn't NaN, then I know longer know the momentum isn't precisely defined.
        claudius 12y ago
        > If I know the complete wave function of the system, then knowing the wave function at a future point in time is trivial. Just apply the time evolution operator. But wouldn't the regular measurement cause a collapse onto a randomly-chosen eigenstate of the measured operator? That is, if we have a PRNG based on a regularly measuring the lava lamp, then to predict the state after N steps, we not only have the issue of the randomly chosen N-th measurement but also have to take into account the random results of the N-1 previous measurements, which can potentially evolve into entirely new directions. Overall, it's difficult to place a lava lamp over human time scales, as both are far from the usual quantum/classical limits: We know that even in thousands of years’ time, Earth will still revolve mostly deterministically (in the classical sense) around the sun. Similarly, electrons will hardly ever behave deterministically. Lava lamps and a couple of years are oddly in between.
- michaelbuckbee 12y ago
  Related: video of a real life dice rolling machine : http://m.youtube.com/watch?v=7n8LNxGbZbs http://m.youtube.com/watch?v=7n8LNxGbZbs IIRC it was built because the founders just could not get people to believe that the dice rolls the generated in software were sufficiently random.
- ghshephard 12y ago
  Didn't it turn out to be the case that SGI discovered that they got the same amount of randomness from the CCD from just taking a picture with the lens cap on?
  - bostik 12y ago
    That sounds plausible... do you happen to have any references at hand to confirm it?
  - wyager 12y ago
    > they got the same amount of randomness It's hard to quantify randomness. It's possible that whatever test(s) they were using reported similar results, even though the data from a lens-capped camera might be somewhat predictable if you know the physical properties of the device. I know individual models of camera frequently have very similar thermal and electrical noise profiles, so that wouldn't be too surprising to me.
hellyeasa 12y ago
Beautiful article.
hazz 12y ago
>Determined to pursue the idea further, Craven contacted Dunnett’s widow and purchased the man’s patent for a sum of less than £20 (about $30 USD). This is slightly misleading. If that was the actual price he paid, it was the equivalent of about £500 today.
GuiA 12y ago
I have a lava lamp on my desk at work- not only does it attract attention (more so than the more boring plasma globes), it's also very relaxing to watch when thinking about some bug or implementation detail. Unfortunately, the quality of the ones you find today is pretty dismal, and they're easily ruined if you leave them on for too long or if they stay in sub-optimal temperatures (e.g. an office building that gets cold over the weekend). Collectors seem to favor the Lava Lite from the 80s for durability.
- deckiedan 12y ago
  I also do. And - funnily enough, once I got mine on my desk, one of the others in the office brought his in from home, and a third engineer asked his wife for one for Christmas so now he has one on his desk as well...
  - deckiedan 12y ago
    Oh, re. reliability, I turn mine on every morning, and off when I leave each night. I wouldn't leave it on overnight. One of the other guys has his on a timer, I believe.
- kawsper 12y ago
  I remember my friend had one, and it was on every time I visited so I could look at it. I am tempted to get one, but I am a bit skeptical with the quality as well.
PhantomGremlin 12y ago
Sadly, the article didn't mention one big problem that will become worse and worse going forward: incandescent bulbs are on the way out. I have a lava lamp that uses a 40 W "appliance light bulb" as a light and heat source. I haven't been able to buy a "frosted" appliance bulb in a number of years. I was able to buy a "clear" bulb a while ago, but the light isn't quite as pleasant from it. And in a few years I'm sure all incandescent bulbs will go the way of the Dodo bird.
- egypturnash 12y ago
  Awaiting the redesign that uses a heating coil combined with LED lights that can be tuned to any color.
  - SwellJoe 12y ago
    This was my immediate thought a few paragraphs in. In my head, I was thinking, "That wastes a lot of energy, and you have to pick your color at purchase time." Why not formulate a combination of fluids that requires less heat to operate, and use a multicolor LED for infinite colors?
- KC8ZKF 12y ago
  http://www.amazon.com/APPLIANCE-LIGHT-FROSTED-INCANDESCENT-VOLTS/dp/B000STFXZU http://www.amazon.com/APPLIANCE-LIGHT-FROSTED-INCANDESCENT-V...
  - PhantomGremlin 12y ago
    Thanks for the pointer. I see that the bulborama website (the actual seller on Amazon) has lots of obscure bulbs. I love LED lightbulbs, e.g. the Philips 60 W equivalents I've been buying. But for some applications the older incandescents and halogens are better.
- tomjen3 12y ago
  That is the fault of the EU, they banned sales of incandesent lightbulbs in order to be green. Meanwhile the retards move back and fourth between two cities every 6 months and fly all over Europe.
TerraHertz 12y ago
Stating that the formula is still a secret after all these years, isn't google-compatible. http://oozinggoo.com/howto.html http://oozinggoo.com/howto.html
- jgeorge 12y ago
  DIY is still a pretty big pain, I've tried several different kinds from those pages. I have to give Mathmos and/or Lava-Lite credit, they /do/ have the chemistry down pretty well. The commercial ones are far more reliable than homebrew.
ansible 12y ago
Funnily enough, my lava lite quite very reliably after a couple hours. It will run normally for a while, and then it will just have a big blob in the bottom. I suspect that there somehow is not enough heat being dissipated at the top. I had toyed with the idea of 3D printing a heat sink, but my design would have cost about $100 USD. I actually have a USB temperature probe, it would be simple enough to just plot the temp over time and see what's going on.
nn3 12y ago
" Bottles are still filled by hand (one employee is able to get through about 400 per day); as a result, Mathmos lamps start at $80 while cheaper, mass-produced lamps sell for as little as $15. " Let's do a little math. Assuming the person doing that makes $20/h, so $160/day. That makes the cost of the employee per lamp $0.4. I dont think the $65 price difference to China can be explained this way.
- keithpeter 12y ago
  Add on the cost of premises, power, distribution. Then factor in the costs of the components. And realise the wholesale price will be half the retail if they are selling through shops. Direct sales could be full value. Still, I reckon there is a healthy profit.

deleted 12y ago

[deleted]

I remember, at the turn of the millennium, when lava lamps were actually used to produce entropy. An SGI project called lavarand had a battery of the things bubbling up and down, used low-end digital cameras to capture images and, after some postprocessing, hashed the results to get what was effectively a fairly good PRNG. [0]http://en.wikipedia.org/wiki/Lavarand http://en.wikipedia.org/wiki/Lavarand

baddox 12y ago
Would that be considered a PRNG? I always thought that PRNG implied a completely deterministic sequence based on a relatively simple seed.
- tonysuper 12y ago
  Technically, a lava lamp is deterministic. Still, I'd say that it's "close enough" to be considered a real RNG. There's almost no way to see a pattern in it, and I'm pretty sure that it would be completely impractical to simulate the contents inside, even if you knew all the initial conditions.
  - baddox 12y ago
    Yeah, I meant "deterministic" as in "generated using standard computations starting from a simple seed." Whether the lava lamp itself is deterministic, or the Universe moreover, is another issue.
  - PhantomGremlin 12y ago
    > Technically, a lava lamp is deterministic. Technically, it's only "deterministic" if you can fully establish the initial state. That's not possible, if for no other reason than the Uncertainty Principle [1] prevents you from measuring the initial conditions carefully enough. Plus you're not really dealing with a closed system, so basically the entire Universe can influence your system going forward. Chaos theory [2] says that you're fighting a losing game if you think it's deterministic. [1] http://en.wikipedia.org/wiki/Uncertainty_principle http://en.wikipedia.org/wiki/Uncertainty_principle [2] http://en.wikipedia.org/wiki/Chaos_theory http://en.wikipedia.org/wiki/Chaos_theory
    - sopooneo 12y ago
      Even if you could determine the initial state, wouldn't quantum effects, aggregating over time, make it non-deterministic?
      - PhantomGremlin 12y ago
        That's a really good question. I'd love to hear the answer from a physicist in the know. Assume you could overcome the uncertainty principle or observer effect and you could fully determine the initial conditions of the entire system. You knew the position and momentum of every atom. You knew the spin of every electron. Etc. Etc. Etc. Doesn't the inherent nature of quantum mechanics say that it's still impossible to predict the state of that system at some future time? Interactions only occur probabilistically, and there is no way to predict them a priori.
        rprospero 12y ago
        Physicist here. In terms of predicting the "future state", it depends on what you want to call the "state". If I know the complete wave function of the system, then knowing the wave function at a future point in time is trivial. Just apply the time evolution operator. However, knowing the wave function at a given point in time doesn't tell me the position or momentum - it just tells me the probability with which I'll measure a given position or momentum. So knowing the "state" still means that my measurements will have random components. On a slightly different note, when you talk about knowing the exact position and momentum of every particle, you're not talking about overcoming a physical limitation, but a mathematical one. To put it differently, if I know that the momentum is exactly zero, I do know that the position is. The problem is that the position is NaN. If the position isn't NaN, then I know longer know the momentum isn't precisely defined.
        claudius 12y ago
        > If I know the complete wave function of the system, then knowing the wave function at a future point in time is trivial. Just apply the time evolution operator. But wouldn't the regular measurement cause a collapse onto a randomly-chosen eigenstate of the measured operator? That is, if we have a PRNG based on a regularly measuring the lava lamp, then to predict the state after N steps, we not only have the issue of the randomly chosen N-th measurement but also have to take into account the random results of the N-1 previous measurements, which can potentially evolve into entirely new directions. Overall, it's difficult to place a lava lamp over human time scales, as both are far from the usual quantum/classical limits: We know that even in thousands of years’ time, Earth will still revolve mostly deterministically (in the classical sense) around the sun. Similarly, electrons will hardly ever behave deterministically. Lava lamps and a couple of years are oddly in between.
michaelbuckbee 12y ago
Related: video of a real life dice rolling machine : http://m.youtube.com/watch?v=7n8LNxGbZbs http://m.youtube.com/watch?v=7n8LNxGbZbs IIRC it was built because the founders just could not get people to believe that the dice rolls the generated in software were sufficiently random.
ghshephard 12y ago
Didn't it turn out to be the case that SGI discovered that they got the same amount of randomness from the CCD from just taking a picture with the lens cap on?
- bostik 12y ago
  That sounds plausible... do you happen to have any references at hand to confirm it?
- wyager 12y ago
  > they got the same amount of randomness It's hard to quantify randomness. It's possible that whatever test(s) they were using reported similar results, even though the data from a lens-capped camera might be somewhat predictable if you know the physical properties of the device. I know individual models of camera frequently have very similar thermal and electrical noise profiles, so that wouldn't be too surprising to me.

hellyeasa 12y ago

Beautiful article.

hazz 12y ago

>Determined to pursue the idea further, Craven contacted Dunnett’s widow and purchased the man’s patent for a sum of less than £20 (about $30 USD). This is slightly misleading. If that was the actual price he paid, it was the equivalent of about £500 today.

GuiA 12y ago

I have a lava lamp on my desk at work- not only does it attract attention (more so than the more boring plasma globes), it's also very relaxing to watch when thinking about some bug or implementation detail. Unfortunately, the quality of the ones you find today is pretty dismal, and they're easily ruined if you leave them on for too long or if they stay in sub-optimal temperatures (e.g. an office building that gets cold over the weekend). Collectors seem to favor the Lava Lite from the 80s for durability.

deckiedan 12y ago
I also do. And - funnily enough, once I got mine on my desk, one of the others in the office brought his in from home, and a third engineer asked his wife for one for Christmas so now he has one on his desk as well...
- deckiedan 12y ago
  Oh, re. reliability, I turn mine on every morning, and off when I leave each night. I wouldn't leave it on overnight. One of the other guys has his on a timer, I believe.
kawsper 12y ago
I remember my friend had one, and it was on every time I visited so I could look at it. I am tempted to get one, but I am a bit skeptical with the quality as well.

PhantomGremlin 12y ago

Sadly, the article didn't mention one big problem that will become worse and worse going forward: incandescent bulbs are on the way out. I have a lava lamp that uses a 40 W "appliance light bulb" as a light and heat source. I haven't been able to buy a "frosted" appliance bulb in a number of years. I was able to buy a "clear" bulb a while ago, but the light isn't quite as pleasant from it. And in a few years I'm sure all incandescent bulbs will go the way of the Dodo bird.

egypturnash 12y ago
Awaiting the redesign that uses a heating coil combined with LED lights that can be tuned to any color.
- SwellJoe 12y ago
  This was my immediate thought a few paragraphs in. In my head, I was thinking, "That wastes a lot of energy, and you have to pick your color at purchase time." Why not formulate a combination of fluids that requires less heat to operate, and use a multicolor LED for infinite colors?
KC8ZKF 12y ago
http://www.amazon.com/APPLIANCE-LIGHT-FROSTED-INCANDESCENT-VOLTS/dp/B000STFXZU http://www.amazon.com/APPLIANCE-LIGHT-FROSTED-INCANDESCENT-V...
- PhantomGremlin 12y ago
  Thanks for the pointer. I see that the bulborama website (the actual seller on Amazon) has lots of obscure bulbs. I love LED lightbulbs, e.g. the Philips 60 W equivalents I've been buying. But for some applications the older incandescents and halogens are better.
tomjen3 12y ago
That is the fault of the EU, they banned sales of incandesent lightbulbs in order to be green. Meanwhile the retards move back and fourth between two cities every 6 months and fly all over Europe.

TerraHertz 12y ago

Stating that the formula is still a secret after all these years, isn't google-compatible. http://oozinggoo.com/howto.html http://oozinggoo.com/howto.html

jgeorge 12y ago
DIY is still a pretty big pain, I've tried several different kinds from those pages. I have to give Mathmos and/or Lava-Lite credit, they /do/ have the chemistry down pretty well. The commercial ones are far more reliable than homebrew.

ansible 12y ago

Funnily enough, my lava lite quite very reliably after a couple hours. It will run normally for a while, and then it will just have a big blob in the bottom. I suspect that there somehow is not enough heat being dissipated at the top. I had toyed with the idea of 3D printing a heat sink, but my design would have cost about $100 USD. I actually have a USB temperature probe, it would be simple enough to just plot the temp over time and see what's going on.

nn3 12y ago

" Bottles are still filled by hand (one employee is able to get through about 400 per day); as a result, Mathmos lamps start at $80 while cheaper, mass-produced lamps sell for as little as $15. " Let's do a little math. Assuming the person doing that makes $20/h, so $160/day. That makes the cost of the employee per lamp $0.4. I dont think the $65 price difference to China can be explained this way.

keithpeter 12y ago
Add on the cost of premises, power, distribution. Then factor in the costs of the components. And realise the wholesale price will be half the retail if they are selling through shops. Direct sales could be full value. Still, I reckon there is a healthy profit.