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What are “actual pictures” of atoms actually pictures of?

273 points| ColinWright | 9 years ago |askamathematician.com | reply

55 comments

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[+] semi-extrinsic|9 years ago|reply
Well, as the article points out, the things being imaged are most definitely actual atoms. The only thing TFA is nitpicking about is that light isn't used to image those atoms.

This is about as interesting as pointing out the fact that an ultrasound picture of a baby isn't an "actual picture", since we use sound instead of light to make the image.

[+] Animats|9 years ago|reply
The concept of the scanning tunneling microscope is so simple and ridiculous that it was probably thought of and dismissed long before someone built one. "You're going to image atoms by dragging a tiny needle across them"? Yet that's pretty much how it works.

The first one was built in 1981, but one could have been built in the 1950s. Piezoelectric crystals were known. Raster scanning circuits were known. Feedback circuits for controlling the height were known. The tricks for making one-atom sharp points were not known, but the earliest STMs just stretched out a tiny platinum wire until it broke, and sometimes you got a one-atom point.

Hobbyists have built STMs.[1] It's simpler than building a 3D printer.

[1] https://dberard.com/home-built-stm/

[+] lanna|9 years ago|reply
It is the distinction between pictures and photographs: they definitively are pictures of atoms, but they aren't nor could ever be photographs.

Ultrasounds also are pictures, but not photographs.

[+] James001|9 years ago|reply
No I disagree. An ultrasound picture of a baby accurately reflects the actual form of the baby. A Scanning Tunneling Electron Microscope does not accurately reflect the form of an atom because it simply uses an artificial dot to represent the presence or absence of an atom. In short, the "map" that STM's give us is abstracted from reality and does not accurately portray an atom (in large part because STM's still simply due not measure at the scale of an atom).
[+] Stratoscope|9 years ago|reply
I found the article really interesting and learned a few things from it.

I do know how an ultrasound image works, and I had some basic knowledge about scanning tunneling microscopes, but this article - and the many links in it - were definitely worth my time reading.

[+] amelius|9 years ago|reply
Isn't it possible to make an image using light, but by computing the "real" image from the interference pattern (of a single non-repeating atom/structure)? And if there is more than one solution, then perhaps by using images from multiple angles, or with different wavelengths?
[+] lisper|9 years ago|reply
One of my first jobs out of college was doing manual chip layouts (which will give you some idea of how old I am). Once the layout was done, the design was sent to a "mask house" which would print the layout onto a series of glass plates (the "masks") which were then used in the chip fabrication process. When the masks for my first chip came back I popped one of them into a bench microscope to see what it looked like. I was expecting to see my design in black-and-white printing, but all I could see (of course) were rainbows because the mask was effectively a diffraction grating. This was my first visceral encounter with quantum mechanics. I knew there was a pattern there, but I could never see it directly with my own eyes.
[+] kens|9 years ago|reply
What era of chip layout was this? I'm surprised that manual chip layout was still being done when chip features were that small. I look at 1970s chips a lot, and the features are easily visible under a microscope, as they are much larger than wavelength-sized.
[+] kens|9 years ago|reply
The linked video "A Boy And His Atom: The World's Smallest Movie" is entertaining. IBM made a stop-motion animated movie from individual atoms.

https://www.youtube.com/watch?v=oSCX78-8-q0&feature=youtu.be

[+] asmithmd1|9 years ago|reply
It was linked with the text "all manner of jackassery" I am glad to know I am not the only one who thought that video was a waste of time.
[+] Artlav|9 years ago|reply
Well, an image is a representation of something in a way that humans can see. Whether waves, electrons or poking sticks were used doesn't change the fact of it being an image.

Say, a dolphin's echolocation might let him "see" a diver using sound - http://i.imgur.com/CS6wkNV.png , which would still be considered an image, even though it's using sound.

Anyway that's just semantics, and an STM is still a damn impressive piece of kit.

[+] blowski|9 years ago|reply
Yeah, it's not a photo but it is an image or picture. The article is doing a bad job of defining its terms, but still it's interesting for a layman like myself.
[+] ridgeguy|9 years ago|reply
Or even when the representation is something humans can't see. Hence the word "imagination".
[+] joshumax|9 years ago|reply
I built an STM a while back for fun and when people ask me how I managed to "image" atoms I usually use the analogy of the STM being like a "microscope sonar" where the atoms are "blips" on a plane (the sonar map). Sure it's not actual EM radiation landing on a CMOS detector but it's still pretty neat nonetheless.
[+] fluxsauce|9 years ago|reply
> This technology has been around for decades and, like the advent of the synth, has given rise to all manner of jackassery.

What's with the synthesizer hate? That seems random.

[+] Stratoscope|9 years ago|reply
That was the weirdest part of this article. I enjoyed the whole thing until the end, but why does the author call IBM's cute and amazing movie "A Boy and His Atom" jackassery?
[+] B1FF_PSUVM|9 years ago|reply
> synthesizer hate

Some people feel very strongly that sound should only be produced by natural (non-GMO) organic means, such as rubbing horsehair on catgut, banging sticks on skins or yelling painfully loud.

They're still sore about Moog.

(He was pulling your leg, and so am I. Mostly. Synthpop ... well, least said, soonest mended.)

[+] Aelinsaar|9 years ago|reply
I love that offhanded comment about how the helical structure of DNA is not at all obvious from that crystallography. All the more impressive then, the history of that discovery.
[+] dekhn|9 years ago|reply
Like many things about the article it's hard to tell when the author is joking.

Knowing DNA was helical from the fiber diffraction images (not crystallography- they were working with DNA fibers, not crystals) was actually "obvious". A helix forms a distinctive cross pattern, this can be (and was) predicted easily from diffraction theory applied to a helical structure.

[+] jdetle|9 years ago|reply
I strongly encourage anyone who is thinking about this to read: "A Different Universe" by Robert Laughlin. This is one of his main concerns of modern science, and although its kind of a muddled argument he thinks that the emergent phenomena captured by photographs are entirely misapplied to atomic forces.
[+] mehrdada|9 years ago|reply
I cannot see (pun intended) how "normal" seeing is fundamentally different. One basically sees by measuring their interactions with photons and deducing how something "looks like" vs. measuring interactions with electrons in STM and making a similar deduction.
[+] polytap|9 years ago|reply
The strange barb at music synthesizers was uncalled for.
[+] yborg|9 years ago|reply
His point was that it is common for a "new" technology to be used just ... because it's there. There was a lot of very bad music made in the early-80s when digital synths became available, and IBM using an AFM to make an advertising blurb could be considered in thie vein.
[+] weberc2|9 years ago|reply
I think we may have DDOSed this site. I'm getting "Error establishing a database connection".
[+] moptar|9 years ago|reply
There's a philosophy idea that in order to say we can "see" something, we have to be able to collect consistent information by several different methods. For example if all we have is a STM, then we don't know which parts of the image are artifacts and which are real so we haven't seen anything. But if we have an STM and crystallography, we can have more faith in the features that are common to both images - such as interatomic distances and the geometry of crystal structure. But we still couldn't say that we've seen the shape of an atom since that would look different in each instrument's image.

A great example is people who "discovered" lost cities under the sea. They saw regular patterns of lines on the seafloor in Google Earth and interpreted them as ancient roads or walls. But they were only seeing artifacts from ships that had sailed back and forth in straight lines collecting data. If they had looked both at those sonar scans and some other data for the same location, they would have only seen the lines on one image and been able to conclude that they were either an artifact of the sonar or below the level of sensitivity of the other instrument.