
The Lava Lamp Just Won't Quit - ryan_j_naughton
http://priceonomics.com/the-lava-lamp-just-wont-quit/
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bostik
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)

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ghshephard
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?

~~~
wyager
> 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.

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GuiA
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
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
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.

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hazz
>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.

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PhantomGremlin
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.

~~~
tomjen3
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.

~~~
SwellJoe
Is the word "retard" really a necessary or useful addition to this sentence?
It is roughly the equivalent of calling someone "nigger" or "faggot" as an
insult. When used in this way it is demeaning to the developmentally disabled.

I understand that this is somewhat common usage on the Internet at large, but
I believe we'd all like to see Hacker News be better than the Internet at
large. And, I'm sure you don't intend harm or insult anyway (other than the
"people who move back and fourth between two cities"); but, the harm is there,
whether intended or not.

~~~
tomjen3
Unless you are developmentally challenged you should not comment on whether
things are offensive. Lets not turn HN into tumblr.

~~~
SwellJoe
So, I can't call out racism when I see it? Can't call out misogyny in a
conversation with only men in it? Can't call out oppressive language in any
circumstance unless I am directly effected by it? No, I don't think that's the
way it works, and it's not the way it should work. I hit the privilege
lottery: I'm white, male, able-bodied, middle class, American. If I'm
unwilling to call oppression what it is, I'm empowering the oppressive
behavior.

I believe my request was polite and stated without malice or (much) judgment.
I would ask you to consider where your desire to argue with that request comes
from.

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nn3
" 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
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.

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TerraHertz
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
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.

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ansible
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.

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hellyeasa
Beautiful article.

