If I asked you to tell me the day of the week, you might hesitate for a moment. That's because our sense of time has been warped by the upending of our normal rhythms. Your usual markers for the passage of minutes and hours and days have been disrupted by of lock-outs and shut-ins. With school, work and social activities all jumbled up in unfamiliar patterns, it's hard to distinguish if it's three days till the weekend or if it's been a month since you saw your sister. Sure, you can look at a calendar or your phone or your watch and get a definitive answer. But time seems to pass differently than it did before March. Maybe like dog years, we need to recalibrate and use a new system of measurement called pandemic time.
In some sense that's what researchers at Goethe University did, though they went the other direction. As reported recently in a study published in the journal Science, they were trying to track time in an experiment involving what's known as the photoelectric effect. Without getting too into the Einsteinian weeds, that phenomena is what happens when you hit a material with some kind of radiation, including light. The result is that a part of the original is ejected in the form of electrons. Measuring how fast those electrons get kicked out is the kind of useful info that makes things like night vision goggles and CAT scans possible. And the more precise that measurement, the more accurate those devices can be.
The scientists in Germany were working on clocking on long it takes a particle of light to cross a single molecule of hydrogen. Needless to say, they weren't using a regular stopwatch, but the quantum physics equivalent. And that's because the duration we're talking about is seriously fast. Just how quick? In the past they would have used a scale based on a period of time called a femotosecond, a unit of time used by Ahmed Hassan Zewail in his Noel prize winning work using lasers in 1999. For the record that is one millionth of one billionth of a second. Put another way, a femtosecond is to one second as one second is to 31.71 million years. So yeah, we're talking short.
But it turns out that it wasn't short enough: that darn electron popped out before they could double click the button. So they had to move to a different unit of time. And what's smaller than a femtosecond? To capture that tiny an increment they had to go down two orders of magnitude, bringing them into the realm of zeptoseconds. That unit of speediness is equal to a trillionth of a billionth of a second, a number written as a decimal point followed by 20 zeros and then a 1.
As it turns out it took 247 zeptoseconds for the electron to make its dash across the atom. And even then scientists note that there is still some wiggle room. Said physicist Reinhard Dörner, "We observed for the first time that the electron shell in a molecule does not react to light everywhere at the same time." That means they may have to drop down another level to capture that subtle difference, into the realm of yactoseconds. Unfortunately, that's just a theoretical guess, as they have no way of measuring anything that fast, other than to say it might be faster than Amazon Prime.
Theoretical or not, it makes sense that you can always go up or down one more. I was tracking an important delivery sent via FedEx and was surprised to get a notice that it got there on the same day I sent it. I called in to make sure there was no problem, and that my package hadn't been lost. When the agent punched it up, she said that no, it was still in transit, that the notice related to another delivery sent by someone else. When I queried her about the alert, she said that it happens sometimes, as they had to reuse some numbers as they were running out. I paused before responding: "I'm pretty sure that's impossible. You can't run out of numbers. Just add one more." I'm no mathematician, but as confirmed by the work of Dörner and his colleagues, I think I was standing on pretty firm ground.
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Marc Wollin of Bedford is fascinated by time and numbers. His column appears regularly in The Record-Review, The Scarsdale Inquirer and online at http://www.glancingaskance.blogspot.com/, as well as via Facebook, LinkedIn and Twitter.
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