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Atomic Orbitals Imaged
joshv writes "Ever think that physics professor was smokin dope as he described those mysteriously shaped clouds of electron probability floating around atoms? Here's proof. Someone has managed to image atomic orbitals using X-ray crsytallography." The story's from Scientific American; very cool stuff. This may be old hat to physics grads, but it's interesting to us laypeople. ;-)
What is looking? Some process that gives you information on the object you look at. On the physical level this exchange of information turns down to an fundamental interaction. And those change the state of the observer and the object.
To be truthful, probably 99% of the physists out there are either doing the work at the quantum level (and thus can be called physical chemists), or work at the extreme macroscale (that is, universal scale), and thus can be called astrophysists.
Almost everything in between was solved by Newton way back when, and Einstein in the early part of this century, except for the connection between a 'small' number of molecules (on the order of 1 to 10^10) and the quautum theory level. And that's the job of chemistry :-)
"Pinky, you've left the lens cap of your mind on again." - P&TB
"I can see my house from here!" - ST:
The problem we have here is that we try to extrapolate a statement from basic physics, from very simple, idealistic situations, like the path of a particle to very complicated situations, like the free will of an intelligent being. Very easy to be victim to improper generalization.
Example: I am able to write a program for a computer, that pretty much gives determined output, despite the fact that all particles making up my box are subject to the Heisenberg principle.
Of course a cosmic particle might flip some bit, or all particles (and thus my box) might show up on Mars in a second, that is all perfectly legal under present known laws of physics, just extremly unlikely.
Thus, I suspect that the details in this SciAm are about as deep as they are in the Nature or Science article, just rewritten to a slightly lower reader level (not too low, mind you, just low enough for the scientific layman to understand). Yes, you should expect contriversy about it. If I remember correctly, the Cold Fusion project of years back underwent a similar treatment. And if you look at the Nobel prizes in Chemistry or Physics and note where the first reported mention of the work occured, I'd expect that you'd also find contrivesry as the idea was tossed around the scientific community.
Now, there is one last point: both Science and Nature are what are known as peer-reviewed journals: before you can publish in those, your article is subjected to critism from at least 3 experts in the field (these experts are anonymous). If they find something fishy or questionable, they'll ask you to fix it , or not approve the article for publication. The fact that it DID get published means that at least 3 experts agree with the results and how the researchers got to them. However, another cavaet - from a chemistry standpoint, this result makes me want to shout horray, as it proves something that's only been shown to work in theory. It's rather easy to ignore possible problems in the mechanics of the experiment for a result like this.
However, now that the technique is out there and reported, you'll see others trying to repeat this, and within 6 months, we'll know if we have the next cold fusion, or the next Nobel-prize winning award.
"Pinky, you've left the lens cap of your mind on again." - P&TB
"I can see my house from here!" - ST:
Actually, quantum mechanics has little to do free will (or the mind in general, Penrose, et al's beliefs aside). There has been a great deal of discussion about whether quantum mechanics allowed for a 'cheat' to recover free will, usually structured around the synapses. The theory is that you can sneak uncertainty into ion channels, then add a little nonlinear dynamics and get free will.
IMO, and that of others, this simply doesn't work. It assumes that (1) quantum mechanics is complete and correct, which is far from proven, (2) that for some reason statistical smoothing doesn't happen in synapses, (3) these variation are amplified, due to the 'chaotic' nature of the brain, and (4) that randomness == free will. To be honest, I see no evidence that this *could* work. OTOH, this may be a good thing.
Free will, as most people define it, is about making free choices; that is, being able to choose one alternative over another. By its very nature, this isn't 'free' in the same way that electrons are 'free'. My choices are determined by who I am, by my ethos, my history, my culture, my beliefs, my passions. They aren't random selection, but utterly determined expressions of my will.
What you are looking for is pure freedom, but the only way to find that is to abandon everything else we believe about freedom: that we make choices, as opposed to selections simply being 'made' on their own. Heidegger wrote about this in Being and Time--I don't have it handy, but his point, IIRC, was that the more we understand Being, who we are, the more we understand how valuable, even wonderful, that psychological determinism is: it makes our choices ours, and gives them meaning and purpose.
I don't get why this is so new (excepting the technique possibly) I was able to demonstrate the shape of orbitals in graphyite using a Scanning Tunneling Microscope last year. Click here to have a peek yourself.
The X-ray and electron beams are not combined, they are collected separately, and the information is combined.
Moreover, the principle difficulty has been completely ignored. Electron beams can be focused to produce a direct image. X-rays cannot be focused for imaging purposes (although crude focussing to concentrate a beam is just possible). As a result, you only get a diffraction pattern with no phase information. The image must be reconstructed by Fourier transformation, which needs the phases. (There is a strong analogy with optical holography, in which a reference beam must be interfered with the diffracted beam to obtain phase information, but with x-rays the coherence length is too short to get a reference beam).
The trick is to use the phases from the low resolution electron image, and some mathematical relationships to reconstruct the missing phases in the high resolution image, which will show your electron orbitals. The problem is unless the statistics are treated very carefully, all you get is an image which confirms the assumtions of the model you used to get the relationships with which you reconstruct the phases.
The mathematical techniques were just coming on line in X-ray crystallography in 1996 and there was still considerable debate back then over their correct application. So there is a fair possibility that these results are correct, but I would suspend judgement until they have been scrutinised for a year or two.
That such a treatment is possible, is not obvious, nature could have been that way, that one had to treat the whole system (like solving the wave equation for all particles at once) in order to make any useful statement at all.
Read this article on Atoms in Molecules by Richard Bader to find out more.
Bader claims that the study of the Laplacian (2nd spatial derivative) of the electron distribution leads to a natural spatial decomposition of a molecule.
Have a look at these great pictures for some simulations based on that AIM theory.
I am still surprised, that during my physics studies, I heard nothing about that treatment. You get exposed to Feynman of course, but Schwinger's formulation of quantumn electro dynamics I knew only as possible but not practical alternative. Very interesting to see Schwingers approach at the heart of this AIM theory.
As the article states, electron orbital clouds have long been used to explain chemical reactions mathematically. Now, it says, they have a physical application as well. However (while not a physics major) I believe the key philisophical question is still unanswered. For those of us who do not believe in any sort of God (or do not feel the idea of God is necessary), materialists, the question we are left with is what governs our everyday activity. Is there free will? Is everything cause and effect? With enough understanding can we eventually be able to determine everyone's future?
The answer for me has always been found in Heisenberg's (sp?) uncertainty principle. He states that you can never know the velocity and the position of an electron at the same moment. What this means to me is that no matter how deep or how complete our physical understanding is, there will always be some bit of uncertainty, if only on the minutest level, that allows us to operate as if we had free will. To me, free will is necessary for me to view my life as a worthwhile pursuit.
Thus, while we can now picture the movements of electrons physically, in doing so, we disturb their velocity and Heisenburg's uncertainty principle is still valid. Therefore, while this may have increased our understanding of the universe, it has not destroyed what I feel is the basic necessity for the pursuit of life: free will.
14 digits of Pi are all we need.
And this is, of course, the nub of the matter. Because a being that does not believe in free will is unlikely to survive, we could have simply have evolved the whole 'consciousness' memeplex without it actually having to exist.
Or maybe not. Maybe it does exist. Maybe it's something to do with quantum effects. Dunno.
So, for now, we get on with living, yeah?
Okay...
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