Why Harmonic Oscillator?

I have a presentation which I sometimes give when asked to talk at schools science fairs called ‘From atoms to climate change’. It’s designed to engage with young chemists, physicists, biologists, geographers and geologists. In the talk I try to show how we can move from the fundamental properties of molecules at the quantum level to using variations in the abundance of stable isotopes of the light elements in nature to determine past climate change. We then look at the climate throughout the Phanerozoic from 560 Ma to the present. One of the take home messages from the talk is that our interpretation of the data has to be grounded in a thorough understanding of the underlying physics and chemistry.  The other one is that you are never too young to start playing with springs and balls (as models of molecules) and having fun with science. Which brings us to the harmonic oscillator. 

Equilibrium isotope partitioning between molecules is driven mainly by the Zero Point Energy (ZPE), that is the quantum mechanical requirement that molecules vibrate with a half quantum of energy even when they are in their ground states at absolute zero. This is a consequence of Heisenberg’s uncertainty principle. Close to the equilibrium inter-atomic distance in a molecule the potential energy, usually represented by a Morse potential, can be approximated by a harmonic function and the vibrational modes by a harmonic oscillator.  If we substitute one of the atoms of the molecule with an isotope of the same element we change the zero point energy of the molecule and thus the vibrational frequency of the bond. The difference in zero point energies between the isotopically substituted and non-substituted molecules is small, typically a few ten’s of joules per mol, but enough to drive measurable isotope partitioning between molecules in nature.

Hence the blog is called Harmonic Oscillator as it provides the fundamental link between physics and the effect of temperature on isotope partitioning and thus our ability to use isotopes to measure past earth surface temperatures.

Convoluted I know but an illustration of how my mind works.

20 Responses to “Why Harmonic Oscillator?”

  1. PhilJourdan Says:

    Not convoluted, but poetic! Science does not have to be all numbers and graphs.

  2. Ruhroh Says:

    I would enjoy it if you could hang a few Isotope-centric reports on this site.
    I’ve not had good luck in finding them, before hitting a pay-wall.

    Thanks in advance.

  3. Stu Pidd Says:

    In your firat paragraph, please replace ‘never to young’ with ‘never too young’.

  4. RickA Says:

    Good luck with the new blog!

    I wandered over from Lucia’s – The Blackboard.

    I will be a regular reader – as I am interested in science in general.

  5. vjones Says:

    Good Luck Paul! I saw the link on Lucia’s site.

    Wow. I was aware of biological partitioning of isotopes and had a reasonable understanding of the whys, but I’d never really thought about temperature effects before. Great explanation.

    I agree with what you said in your Welcome! statement about everyone having the right to engage in science, however it saddens me that so many are switched-off and not interested in even the most basic understanding of scientific issues.

    I see Lucy has a post at tAV tonght.


  6. windansea Says:

    welcome to the cybersphere

    there is another blog called delayed oscillator by a dendro type here:


  7. Phil Jones Says:

    Nice to see one of us is being open!!! Came from the Bishop – good luck & all the best.

  8. Ayrdale Says:

    Stopped in via Bishop Hill.

    Paul, may I draw this to your attention, and invite your comment ? From…

    ” Jerome Ravetz, of Oxford University in the UK…environmental consultant and professor of philosophy of science best known for his books challenging the assumptions of scientific objectivity…”


  9. hro001 Says:

    Sir, your voice is welcome breath of fresh air from East Anglia. Like others who have posted here, I look forward to learning from you.

  10. Inversesquare Says:

    I get the feeling that I will end up learning a lot from your bog!

  11. Inversesquare Says:

    one of the reasons your blog title got my attention is because I work with audio…. I have a real interest in wave physics and I also have a friend who makes these:

    http://www.google.co.nz/search?q=harmonic generator intermodulator&ie=UTF-8&oe=UTF-8&hl=en&client=safari

  12. Dodgy Geezer Says:

    Congratulations are in order for taking the trouble to present a platform for your views to the wide and unruly audience of the blogosphere! It will not be an easy task but I hope you will persevere – we really need your level of expertise influencing the discussions.

    One aspect of the CO2 warming process which has always given me trouble is the claim on one side that the basic physics is settled and final, while the doubters throw in comments about co2 absorption saturation being logarithmic, and the lack of a tropospheric hot-spot. Detailed research and discussion of these points seems to be comparatively rare on the high-quality sites, and I hope you will be able to cover some of this field in your future postings….

  13. TCO Says:

    I’d be interested in how much researchers can still be curiosity seekers, when they are managing laboratories, not doing the work themselves (the typical US pattern of a professor with grad students in the US).

  14. Jimchip Says:

    I guess I should say I dropped by Lucia’s and wandered over here. I don’t know why I like this old page so much but maybe I just think it’s cute:

    Anyway, Harmonic Oscillator is a better name than Symmetric Stretch. People might have thought you’re a well-balanced basketball player.

  15. Anthony Watts Says:

    Hello Paul,

    If you are interested in using it, I’ve created a wordpress image header for you to jazz up your site for you themed to fit your blog name.

    You can download it here:

    It is sized for the current “Kubrick” wordpress theme you are using, see the left sidebar in your WP admin panel for “appearance” and then “custom header” to upload it.

    You’ll have to turn off your existing header text so it doesn’t bleed over the image.

    Don’t feel obligated, I won’t be offended if you don’t use it. Just my way of saying welcome to blogging

  16. Anthony Watts Says:

    Also, if you’d prefer to use it, but don’t want people to know the source, just delete this and the previous comment

  17. Anthony Watts Says:

    You can preview what it looks like here on an empty blog I was considering once.


    To turn off the text from your original header, simply click on the the “hide text” tab under the header image after it is uploaded by returning to the “custom header” link from the sidebar, then click “save” and it will look like the sample above.

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