Why your hair dulls the sharpest razor blades
Ever wonder how soft hair can dull a steel razor? So did scientists at MIT.
- Steel is fifty times harder than hair, yet shaving razors dull in a hurry.
- A new study finds much of this is caused by hair cracking razors at points of imperfection.
- The findings may lead to new ways of making razors that last longer.
Everybody who shaves regularly knows that most razors only last a few shaves. Given that hair is not nearly as hard as steel, this tendency seems odd. Why should soft hair degrade steel? Until now, the assumption had always been that each shave dulled the blade to the point of it losing its sharp edge.
Now, a curious new study out of MIT finds that this isn't what happens at all. Instead, your hair can crack stainless steel under the right circumstances.
An extremely magnified image of a razor blade cutting hair.
Lead author Gianluca Roscioli grew his facial hair out for three days before shaving. He then brought his razors into the lab to examine them under an electron microscope. While the team expected to see even dulling on the blade edge, they instead noticed strange C-shaped chips missing. Intrigued, they attached a camera to the microscope so they could record the blade cutting the hair. At the same time, they investigated the properties of the razors at the microscopic level.
This apparatus revealed that, when the razor blade hit the hairs at non-perpendicular angles, small cracks formed. These tended to develop in boundary areas between where the steel was harder and where it was softer due to differences in the properties at each location caused by the manufacturing process. Over time, these cracks grew into chips. While these chips are too small to see with the naked eye, they were large enough to reduce the blade's effectiveness.
Roscioli told NPR, "The size of the chips are about 1/10 of the diameter of a human hair."
The chips can be caused by hair of any thickness and appear to be unavoidable in blades with standard imperfections.
The finding surprised other scientists, who also quickly accepted the explanation. Professor Suveen Mathaudhu of UC Riverside explained to NPR that he had expected a larger role in the dulling process to be played by corrosion but that the findings made a great deal of sense. Other scientists expressed how impressed they were by the quality of the images and the difficulty of the study.
How can we possibly use this information?
The study determined that part of the reason for this chipping is the imperfections in the steel used to make the blades, specifically the lack of uniformity in the composition of the steel at the microscopic level. At least partly, these imperfections are due to the nature of the production process and can be reduced through alternative methods. This study's research team is also working on a new material with more structural uniformity as a possible solution.
These findings may one day lead to longer-lasting razor blades. Given that Americans throw out two billion blades each year, such a discovery's environmental impact would be tremendous.
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The idea of 'absolute time' is an illusion. Physics and subjective experience reveal why.
- Since Einstein posited his theory of general relativity, we've understood that gravity has the power to warp space and time.
- This "time dilation" effect occurs even at small levels.
- Outside of physics, we experience distortions in how we perceive time — sometimes to a startling extent.
Physics without time<p>In his book "The Order of Time," Italian theoretical physicist Carlo Rovelli suggests that our perception of time — our sense that time is forever flowing forward — could be a highly subjective projection. After all, when you look at reality on the smallest scale (using equations of quantum gravity, at least), time vanishes.</p><p style="margin-left: 20px;">"If I observe the microscopic state of things," writes Rovelli, "then the difference between past and future vanishes … in the elementary grammar of things, there is no distinction between 'cause' and 'effect.'"</p><p>So, why do we perceive time as flowing <em>forward</em>? Rovelli notes that, although time disappears on extremely small scales, we still obviously perceive events occur sequentially in reality. In other words, we observe entropy: Order changing into disorder; an egg cracking and getting scrambled.</p><p>Rovelli says key aspects of time are described by the second law of thermodynamics, which states that heat always passes from hot to cold. This is a one-way street. For example, an ice cube melts into a hot cup of tea, never the reverse. Rovelli suggests a similar phenomenon might explain why we're only able to perceive the past and not the future.</p><p style="margin-left: 20px;">"Any time the future is definitely distinguishable from the past, there is something like heat involved," Rovelli wrote for the <a href="https://www.ft.com/content/ce6ef7b8-429a-11e8-93cf-67ac3a6482fd" target="_blank"><em>Financial Times</em></a>. "Thermodynamics traces the direction of time to something called the 'low entropy of the past', a still mysterious phenomenon on which discussions rage."</p>
The strange subjectivity of time<p>Time moves differently atop a mountain than it does on a beach. But you don't need to travel any distance at all to experience strange distortions in your perception of time. In moments of life-or-death fear, for example, your brain would release large amounts of adrenaline, which would speed up your internal clock, causing you to perceive the outside world as moving slowly.<br></p><p>Another common distortion occurs when we focus our attention in particular ways.</p><p style="margin-left: 20px;">"If you're thinking about how time is <em>currently</em> passing by, the biggest factor influencing your time perception is attention," Aaron Sackett, associate professor of marketing at the University of St. Thomas, told <em><a href="https://gizmodo.com/why-does-time-slow-down-and-speed-up-1840133782" target="_blank">Gizmodo</a></em>.<em> "</em>The more attention you give to the passage of time, the slower it tends to go. As you become distracted from time's passing—perhaps by something interesting happening nearby, or a good daydreaming session—you're more likely to lose track of time, giving you the feeling that it's slipping by more quickly than before. "Time flies when you're having fun," they say, but really, it's more like "time flies when you're thinking about other things." That's why time will also often fly by when you're definitely <em>not</em> having fun—like when you're having a heated argument or are terrified about an upcoming presentation."</p><p>One of the most mysterious ways people experience time-perception distortions is through psychedelic drugs. In an interview with <a href="https://www.theguardian.com/books/2018/apr/14/carlo-rovelli-exploding-commonsense-notions-order-of-time-interview" target="_blank"><em>The Guardian</em></a>, Rovelli described a time he experimented with LSD.</p><p style="margin-left: 20px;">"It was an extraordinarily strong experience that touched me also intellectually," he said. "Among the strange phenomena was the sense of time stopping. Things were happening in my mind but the clock was not going ahead; the flow of time was not passing any more. It was a total subversion of the structure of reality."<br></p><p>It seems few scientists or philosophers believe time is completely an illusion.</p><p style="margin-left: 20px;">"What we call <em>time</em> is a rich, stratified concept; it has many layers," Rovelli told <em><a href="https://physicstoday.scitation.org/do/10.1063/PT.6.4.20190219a/full/" target="_blank">Physics Today</a>.</em> "Some of time's layers apply only at limited scales within limited domains. This does not make them illusions."</p>What <em>is</em> an illusion is the idea that time flows at an absolute rate. The river of time might be flowing forever forward, but it moves at different speeds, between people, and even within your own mind.
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Controversial physics theory says reality around us behaves like a computer neural network.
- Physicist proposes that the universe behaves like an artificial neural network.
- The scientist's new paper seeks to reconcile classical physics and quantum mechanics.
- The theory claims that natural selection produces both atoms and "observers".
Vanchurin interview:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="539759cbfd8fcd5b6ebf14a3b597b3f9"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/bmyRy2-UhEE?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
Vanchurin on “Hidden Phenomena”:<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="18886ffd5e5840bb19d4494212f88d82"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/2NDVdNwsHCo?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>Vitaly Vanchurin speaking at the 6th International FQXi Conference, "Mind Matters: Intelligence and Agency in the Physical World." The Foundational Questions...
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