Naked Science Forum
General Science => General Science => Topic started by: dentstudent on 03/11/2008 14:10:34
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My (perhaps naive) thought process is this - please tell me if, where and why it's incorrect. Thanks!
My intial assumption is that all things have "odourant" molecules, which are released into the atmosphere. This release process requires energy. The only state where there is no energy is at absolute zero. Since it is impossible to reach AZ and therefore impossible to reach a state of zero energy, there will always be a (albeit perhaps slow) release of odourant molecules, and therefore everything has a smell which can be "measured".
If my intial assumption is incorrect, and that not all things do have odourant molecules, then this must mean that they do not smell, however sensitive the "nose" or however large the "thing", which seems unlikely.
I suspect that there may be a case for molecules that do not have any suitable smell receptor, and could thus be stated as smell free. But perhaps they do smell, it's just that there isn't anything capable of doing the smelling?
Anyway, I have a cold and can't smell anything anyway.
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I wonder if Neutrinos smell and those underwater tanks are just like nostrils !
Great question. I hope a klevur person (not me !) smells the whiff of this thread and sprays some nostril refreshing answers here !
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My dog has no nose.
How does he smell?
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Just about all materials will release some molecules from their structure into the air so it is probably theoretically possible to smell them if your nose had sensors that could respond to the molecules released.
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Water can't have a smell. You get used to odours if they persist and water is always present in your nose so you would never be able to smell it.
If you want to generalise to the idea of "detection by some means or other, not necessarily the human nose" then the vapour pressure of some things like iron are so low that you wouldn't get a single atom in an average sniff so it couldn't smell either.
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My dog has no nose.
How does he smell?
All together now..... 1....2....3
AWFUL
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Some may believe that they can smell iron they have touched, but it is actually a form of body odour caused by iron...
Ancient human hunters smelt blood on the breeze
26 October 2006
Our ability to detect the characteristic metallic smell left on the skin after handling iron-containing objects like coins and keys may have evolved for a more gory purpose: to help our hunter ancestors track down wounded prey.
Fats on the skin break down to form volatile, strong-smelling substances called ketones and aldehydes when they come into contact with iron - whether it comes from the environment or from haemoglobin in blood - says Dietmar Glindemann, a chemist at Virginia Polytechnic Institute and State University in Blacksburg.
http://www.newscientist.com/article/mg19225754.400-ancient-human-hunters-smelt-blood-on-the-breeze.html
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RD - good post! That's todays "new fact" sorted!
BC - but water still has the potential of being smelled, even if the smeller has become used to it? Also, the iron may release atoms at a very slow rate such that it we are unlikely to get one on a sniff, but as it is still releasing them, can it not therefore still be labelled "smelly"?
Thanks for the thoughts so far!
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To paraphrase Dr Johnson: only noses smell - everything else stinks.
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BC - but water still has the potential of being smelled, even if the smeller has become used to it? Also, the iron may release atoms at a very slow rate such that it we are unlikely to get one on a sniff, but as it is still releasing them, can it not therefore still be labelled "smelly"?
By that logic it's intermittently smelly, which seems silly to me.
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One of the things that I thought about while I was putting together my first answer to this question was the "metallic" smell of a clean iron surface (no oil to create a different smell and protect the surface). The vapour pressure of iron may be very low but the presence of water vapour that deposits in a film on almost all surfaces and the fact that iron rusts, probably releases many more iron atoms into the air than you might expect. This smell of iron is very similar to the smell of various ferrous and ferric solutions.
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BC - but water still has the potential of being smelled, even if the smeller has become used to it? Also, the iron may release atoms at a very slow rate such that it we are unlikely to get one on a sniff, but as it is still releasing them, can it not therefore still be labelled "smelly"?
By that logic it's intermittently smelly, which seems silly to me.
In a different context, radioactive particles can be released intermitantly, hence the blip noise on a geiger-müller counter. This means that the item in question is classed as radioactive, and not intermittantly radioactive, even though the counter is not making a continuous noise. Are the two not analagous?
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Of course, it's important to remember that the ability to smell varies throughout the animal kingdom. We human beings have a rather weak capacity for smell.
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I was looking up some details yesterday about stable isotopes (who says my job is not interesting) and noticed that Nitrogen was listed as odourless (well, it actually listed it as "odorless" but I'm assuming this is the US smelling and not the UK...). Other SI's are oxygen, hydrogen and carbon. Since SI's do not decay, is this the key to odourlessness? (Cue Rowan Atkinson)
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Well in the case of Nitrogen and Oxygen it would be useless to us to be able to smell them because they're always present in the air, and it would be silly if we could always smell it and it potentially masked the scent of our prey or other important smell.
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Of course, after one has been exposed to a smell for a length of time, one ceases to notice it.
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I don't think (most) metals have a smell?
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wether something smells or not depends on wether we have receptors in our nose with which the substance interacts, transmitting signals that the brain interprets as smell. Just because you can't smell something does not mean that it's not present in the air you breath in through your nose. I was once told that the least volatile material found on earth is plutonium, but even then if you have a solid lump of plutonium there will be a non-zero number of plutomium atoms in a gaseous state and therfore you could in principle breath them in. You may not be able to smell them because there's too few atoms to stimulate enough of a response or because you do not have receptors able to respond to them, but that does not mean they are not there.
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Given the above, perhaps the question should be "does everything have a spell (checker)?"