H.C. Urey — one of the authors of the above-cited publication — (April 29, 1893 – January 5, 1981) was an American physical chemist whose pioneering work on isotopes earned him the Nobel Prize in Chemistry in 1934 for the discovery of deuterium. Heavy water is a form of water that contains a larger than normal amount of the hydrogen isotope deuterium rather than the common hydrogen-1 isotope.
This just underscores the lack of understanding between "we need to measure this value" and "we need to understand how this value is calculated" these days. :(
> understanding between "we need to measure this value" and "we need to understand how this value is calculated"
We also need to re-enforce that "how this value is calculated" is just another level of correlation with reality, it is not an absolute, i.e is not how reality "calculates" it for anything except for things that exist purely in the realm of the abstract - where our abstraction is also the definition.
I believe it's this lack of understanding that results in the distorted view of science being the practice of recording absolute truths.
> A US nuclear laboratory is said to maintain a "heavy dog"--fed with heavy water and "heavy" food, and with the heavy isotope deuterium replacing normal hydrogen throughout the whole body.
-- New Scientist, 1976 [1]
And:
> [it] would be invisible to a MRI scanner. The dog would still be clearly visible to the naked eye so apart from confusing the staff operating the scanner I can see no advantage to this.
Deuterium is toxic in high concentrations. It slows down metabolism and inhibits cell division. Mammals die within week if half of the water in the body is replaced with deuterium oxide.
Unfortunately the dog would die before reaching that point; mammals die around the point when 50% of their H2O is replaced with D2O. It's a great story, though.
I don't know about heavy pups but that New Scientist issue is a lot of fun to scroll through. Surprisingly relevant content in parts for being 43 years old.
Turns out being invisible to MRI is not without it’s advantages. NMR (MRI for molecules) uses deuterated solvents so the hydrogen signal from the solvent doesn’t overwhelm the signal from the sample molecules.
About 20 years ago my dad was doing research (at the U of Georgia) that traced how a peptide was metabolized by grasshoppers. They used an isotope of carbon with a 20 minute half-life (C11), but also needed to ensure that the radiation from Carbon-14 and other isotopes was very, very low. Essentially they needed grasshoppers with stable versions of carbon, which you're not going to get from the wild.
So they grew plants and grasshoppers in a sealed environment, with CO2 (and probably other carbon sources) from oil. Since the hydrocarbons in the oil are millions of years old, the carbon is essentially exhausted of radioactive isotopes.
If you carbon dated one of those grasshoppers it would have seemed tens of thousands of years old...
The claim I read is that it is due to the mass of the molecules being different.
The masses being larger should result in them moving slower I think? (At the same temperature)
Allegedly this influences how the diffusion/osmosis works out, resulting in more or less water in the cells on the tongue or something?
It is also possible that I am getting things mixed up with when he tasted extremely pure water, which iirc causes some cells to burst, causing a sweet taste?
As is with all things, once you start getting down to the details most our mental models are just that - mental models.
I am guessing other people have downvoted you for adopting an ignorantly confident tone on something you are not a specialist for - this is probably a bit harsh but perhaps this can be a friendly reminder to keep an open mind about these things.
Yes, Chemistry is effectively the study of electrons, but nature has been shown to be isotopically sensitive. Moreover, I have heard of chemistry on radioactive chemicals being a nightmare to reproduce because there are certain reactions where there are competing reaction pathways which are kinetically controlled and so isotopic interactions can wreak havoc on your products.
Isn't it for the same reason regular, pure water is also sweet?
I don't know the explanation for that one, I always assumed taste buds have neutral taste calibrated for water found in real environments - with salt and minerals dissolved in it.
(This is probably not correct, but I also imagine it like this: AFAIK pure water forces osmosis to go in the other direction than usual, so maybe the taste one feels isn't "positive sweet" but "negative salty".)
Some other neat things I found along the way, mostly on Wikipedia: heavy waters freeze at 4-5 degrees Celsius, the heavier the higher. Frozen heavy water will sink in liquid normal water, and pure "tritiated water" ("super-heavy" water, with tritium hydrogen isotopes) is radioactive and will boil itself if pure enough.
Did anybody else immediately think of the episode in Hogan's Heroes where Hogan convinces Col. Klink to drink heavy water? https://www.imdb.com/title/tt0602322/
I thought of the scene in the old Adam West Batman movie where Batman reconstitutes dehydrated bad guys with heavy water and they are unable to take their feet off the floor (because they’re so heavy).
Sadly, you're remembering wrong. The dehydrated pirates vanish as soon as they're punched! Two of them even pop like bubbles when they accidentally run into each other! Clearly much more scientifically valid.
43 comments
[ 7.2 ms ] story [ 85.2 ms ] threadI expect to find this on the shelf right next to Dirty Lemon Charcoal water shortly.
That's generous.
https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment
We also need to re-enforce that "how this value is calculated" is just another level of correlation with reality, it is not an absolute, i.e is not how reality "calculates" it for anything except for things that exist purely in the realm of the abstract - where our abstraction is also the definition.
I believe it's this lack of understanding that results in the distorted view of science being the practice of recording absolute truths.
> A US nuclear laboratory is said to maintain a "heavy dog"--fed with heavy water and "heavy" food, and with the heavy isotope deuterium replacing normal hydrogen throughout the whole body.
-- New Scientist, 1976 [1]
And:
> [it] would be invisible to a MRI scanner. The dog would still be clearly visible to the naked eye so apart from confusing the staff operating the scanner I can see no advantage to this.
-- source [2]
[1] https://books.google.co.uk/books?id=AhC9t3Q3YMcC&lpg=PA480&o...
[2] https://scicommstudios.wordpress.com/2012/01/08/hydrogen/
Deuterium is toxic in high concentrations. It slows down metabolism and inhibits cell division. Mammals die within week if half of the water in the body is replaced with deuterium oxide.
So they grew plants and grasshoppers in a sealed environment, with CO2 (and probably other carbon sources) from oil. Since the hydrocarbons in the oil are millions of years old, the carbon is essentially exhausted of radioactive isotopes.
If you carbon dated one of those grasshoppers it would have seemed tens of thousands of years old...
https://www.youtube.com/watch?v=MXHVqId0MQc
And chemistry pertains to modification of electrons and bonding energies.
I'm seeing placebo or contamination.
https://en.wikipedia.org/wiki/Kinetic_isotope_effect
The masses being larger should result in them moving slower I think? (At the same temperature)
Allegedly this influences how the diffusion/osmosis works out, resulting in more or less water in the cells on the tongue or something?
It is also possible that I am getting things mixed up with when he tasted extremely pure water, which iirc causes some cells to burst, causing a sweet taste?
I am guessing other people have downvoted you for adopting an ignorantly confident tone on something you are not a specialist for - this is probably a bit harsh but perhaps this can be a friendly reminder to keep an open mind about these things.
Yes, Chemistry is effectively the study of electrons, but nature has been shown to be isotopically sensitive. Moreover, I have heard of chemistry on radioactive chemicals being a nightmare to reproduce because there are certain reactions where there are competing reaction pathways which are kinetically controlled and so isotopic interactions can wreak havoc on your products.
I don't know the explanation for that one, I always assumed taste buds have neutral taste calibrated for water found in real environments - with salt and minerals dissolved in it.
(This is probably not correct, but I also imagine it like this: AFAIK pure water forces osmosis to go in the other direction than usual, so maybe the taste one feels isn't "positive sweet" but "negative salty".)
Soft water is sweet. Hard water tastes fresh.
https://i.stack.imgur.com/J4gay.gif
Some other neat things I found along the way, mostly on Wikipedia: heavy waters freeze at 4-5 degrees Celsius, the heavier the higher. Frozen heavy water will sink in liquid normal water, and pure "tritiated water" ("super-heavy" water, with tritium hydrogen isotopes) is radioactive and will boil itself if pure enough.
Batman’s scientific content wasn’t all that high.