My main contribution to the January 2000 issue of Physics Today was editing “Retinal imaging and vision at the frontiers of adaptive optics,” a feature article by Donald Miller of Indiana University. The article was that month’s cover story and had the catchy cover line “Supernormal Vision.”
In his article, Miller pointed out that humans—even ones with 20/20 vision or accurately prescribed corrective lenses—do not enjoy the full spatial resolution of their retinas. That’s because their eyes’ lenses are imperfect. Although contact lenses and spectacles correct for the most significant aberrations—namely, defocus, astigmatism, and tilt—they leave higher-order aberrations uncorrected.
Those higher-order aberrations can be measured and corrected, but doing so is expensive and technically challenging. What’s more, many of the higher-order aberrations change with the direction of one’s gaze. Contact lenses, which move with one’s eyes, could be used, but the aberrations need to be tracked and compensated for in real time.
Amazingly, Miller and others have created such lenses—but not to give themselves supernormal vision. Instead, they use the lenses and associated equipment to obtain a clear view of patients’ retinas. The goal is to diagnose the early onset of eye diseases that might be missed without the enhanced visual acuity.
This figure from Miller’s article shows what the Statue of Liberty would look like from 3 km away with, (a) normal vision with a 3-mm-diameter pupil, (b) supernormal vision with a 3-mm pupil, and (c) supernormal vision with an 8-mm pupil.
Miller’s article brought to mind an essay by Oliver Gaycken of the University Maryland. Entitled “SuperVision: Images of the technological sublime,” Gaycken’s essay examines popular reaction to Wilhelm von Roentgen’s discovery of x rays in 1895.
As you might guess, the ability to see through body parts inspired awe at the end of the 19th century. Marketers rushed to brand their products, among them a juice press and headache pills, with the name of the wondrous invention. Surprisingly—at least to me—x rays also inspired fear. Gaycken describes several films, stories, and plays in which penetrating vision brings misery. Here is one melodramatic example:
C. H. T. Crosthwaite’s “Roentgen’s Curse,” (1896) offers another vivid document of the ambivalent reception of Röntgen’s discovery. Near the beginning of the story, the narrator and protagonist, a former bacteriologist and analytical chemist, now retired thanks to an inheritance, and recently back from India where he had been involved in the “chase after the cholera microbe” introduces his tale: “I was on the track of a great discovery. I was sure of it. A little more time, a little more toil, and the reward would be mine. I, Herbert Newton, should be hailed as the greatest benefactor of the human race in modern times.” Newton succeeds in inventing a fluid that when applied to the eyes gives the user the ability to see with X-ray vision.
Newton tests the fluid on his dog, and the dog goes insane. This rather arch moment of foreshadowing is lost on Newton, however, who proceeds to administer the liquid to his own eyes. When his wife and son visit him, he regrets his decision. “I dared for one moment to look again, and in that one moment I suffered enough to make me regret for ever the ambition to see with the Divine eye. Two living skeletons walked in, the larger leading the little one by the hand; two chattering, gibbering skeletons . . . Oh God! How terrible! There at my knee was a little skeleton, mouthing at me and aping the motions of life. I closed my eyes again, and my tongue refused to speak.” Newton is brought to the edge of madness and total collapse before the effects of the fluid wear off and he returns to the bliss of normal, limited vision.
When I read about “Roentgen’s Curse,” I wondered how Crosthwaite and the other authors that Gaycken cites came to think that x-ray vision was even possible, let alone plausible. Then, as now, medical x-ray imagers record the photons that pass through an object, not the photons that are reflected off an object. For Crosthwaite’s bacteriologist to see his family as skeletons, he’d need a source of x rays that was positioned between them and his eyes.
Crosthwaite might not have given much thought to the generation and detection of x rays. It’s also possible that having seen x-ray radiographs, he might have likened them to optical photographs and implicitly assumed they were made with a similar arrangement of light source, subject, and camera. Backscattered x-rays are detectable. Indeed, as Gaycken remarks, they form the basis of a modern screening technology, but you still need an x-ray source to make them.
Gacyken’s essay is 1 of 12 that were written for Histories of the Future, a conference held at Princeton University this past February and organized by Princeton historian of science Erika Milam.
Examining past speculations about future technologies might seem odd, given that we know how the histories of those technologies unfolded (or not, if they remain unrealized). But as Milam points out on the conference webpage, “Controversies over scientific ideas, from evolution to climate change, have been contentious as much for their (implied and explicit) futures as for their pasts.” Genetically modified organisms, for example, are troubling to some people not just because of their contested nutritional value but also because of what damage the organisms might cause to our environment in the future.
Unusual Arctic fire activity in 2019–21 was driven by, among other factors, earlier snowmelt and varying atmospheric conditions brought about by rising temperatures.
January 06, 2023 12:00 AM
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Physics Today - The Week in Physics
The Week in Physics" is likely a reference to the regular updates or summaries of new physics research, such as those found in publications like Physics Today from AIP Publishing or on news aggregators like Phys.org.
