March 27th,
2010
My last Ice Science Roundup included a portion on the Mpemba Effect, by which certain circumstances will cause hot water to freeze faster than cold. This is incredibly controversial stuff in ice science circles, for a variety of reasons. To laymen, it seems like total bullshit, because, well, hot water is hotter and stuff. To the experts in the field who are skeptical, the objections are more scientific: Hot water is hotter and such.
OK, so the objections aren’t really so far apart.
Anyway, when last I opined on this freakishness, the problem was that while people as far back a Aristotle have noticed this phenomenon, no one had ever done any really rigorous experiments to try to see if it could be proven, and what was the cause if it could.
Apparently, the folks in Science read this blog, because one of them, David Auerbach has finally gotten around to doing some painstaking research on finding out if the effect really works. Either that, or he was out of ice, had guests coming over for a cocktail party and was desperate to get ice as fast as possible by any means possible. Which it was is left unclear by the article I read in Science News (via Maetenloch in Ace’s ONT)
Auerbach is the first to successfully set up a reproducible result demonstrating the effect. This proves the theory once and for all. Unless you are one of the numerous scientists who still refuse to believe it really works, since, well, hot water is hotter and stuff. And even Auerbach can’t explain his results, only demonstrate the effect. Unless he doesn’t, if you read what the skeptics have to say.
I’m sorry,
I’m more confused about this than I was before you started.
Me too. But it is fun to talk about, and the article is worth a read. And it gives me an excuse to post another cool picture of ice.
March 28th, 2010 at 11:45 am
well it seems that brownridge (http://arxiv.org/abs/1003.3185), not auerbach, has done the most recent research, and is the first one to reproduce the effect reliably.
but he is careful in the article to point out that it’s still comparing h2apples to h2oranges – they specifically chose tap water as the hot specimen and distilled water as the cold specimen because tap water has a higher spontaneous freezing temperature (more impurities = more nucleation sites).
otherwise, using the same types of water, the mpemba is not reproducible. i think this issue is the cocktail geeks’ equivalent of the falling guinness bubbles debate (http://www.stanford.edu/group/Zarelab/guinness/index.html).
john(Quote) (Reply)
March 28th, 2010 at 1:00 pm
John,
Bad reading by me on Brownridge v Auerbach. Got that from starting writing before fully following the chain of blogs leading to the original article.
And yes, I was well aware that they were using different water for the hot and cold samples. That was my point with all the discussion of whether or not the experiment actually confirms the effect or not.
That said, I challenge your assertion that, “the mpemba is not reproducible.” (Emphasis mine) It has not been fully reproduced here, but I get all itchyfied when I hear flat statements about scientific theories.
That said, I’d have liked to have seen more on the methodology used for the freezing. Most of the semi-successful work on Mpemba I’ve read of has focused less on the water’s makeup than on the method of freezing, and container used, etc. Then you can open up a can of worms by how you define “frozen”.
Regardless, I remain skeptical of Mpemba too, but I also think that there is something going on with this issue. I just love seeing people take it seriously enough to keep kicking the tires.
Oh, and for anyone else reading these comments, John has a seriously cool blog. Click on his name to check out Observational Gastrophysics.
Too bad he’s a Harvard guy. Imagine, if you will, how much cooler his stuff’d be if he worked at a serious university like Stanford….
Doug(Quote) (Reply)
March 28th, 2010 at 10:36 pm
definitely a lot of tire-kicking going on – and it’s important that we readers do it too!
right, right, it hasn’t been reproduced in that work, but as brownridge bemoans, there are so many knobs to tweak, with only so many grad students to tweak them. (ok, maybe he didn’t say that last part.) as such, the word ‘effect’ is appropriate; the scientifically sacred title of ‘theory’ doesn’t apply.
and for the record, i’m at mit via stanford, so…
john(Quote) (Reply)
March 29th, 2010 at 6:25 am
“mit via stanford”, huh? Excellent. I guess we can rescind the “Harvard Disqualification” rider on your coolness card!
Doug(Quote) (Reply)
October 23rd, 2010 at 4:59 am
Can I ask if you happen to be from Queensland? You actually sound like an Aussie
Pamela Mickey(Quote) (Reply)