A mind-boggling camera can capture 3D movies at 100 billion frames a second, a new method can rapidly turn plastic waste into clean hydrogen fuel, and researchers figured out a way to calculate the upper limit of the speed of sound: a cool 22 miles per second. Life comes at you fast in this week’s coolest scientific discoveries.
What is it? Earlier this year, California Institute of Technology medical engineering professor Lihong Wang said his lab had developed a camera that could capture as many as 70 trillion frames a second. Now, using similar technology, he’s developed a camera that can film 3D movies at 100 billion frames a second.
Why does it matter? Ultrafast cameras could have uses in the life sciences and in semiconductor research, but they could also help physicists figure out some long-standing head-scratchers — such as sonoluminescence, “a phenomenon in which sound waves create tiny bubbles in water or other liquids,” according to Caltech. Wang explained, “When a bubble collapses, its interior reaches such a high temperature that it generates light. The process that makes this happen is very mysterious because it all happens so fast, and we're wondering if our camera can help us figure it out.”
How does it work? The central technology in the trillions-of-frames-a-second camera is called compressed ultrafast spectral photography, or CUSP, in which a laser fires pulses that last only a femtosecond — that’s one quadrillionth of a second. The laser is combined with optics and a camera capable of capturing the image. The latest advance, which is described in Nature Communications, works similar to how humans understand 3D space: with two eyes that capture slightly different images of the world ahead of us, and a brain that calculates that information to give us a sense of depth perception. Wang said his technology is based on the same principle: “We have one lens, but it functions as two halves that provide two views with an offset. Two channels mimic our eyes.”
What is it? Elsewhere at Caltech, researchers are developing technology that will enable another kind of closer look: They’ve come up with a low-cost sensor that could be used at home to detect COVID-19 infection in people who aren’t yet symptomatic.
Why does it matter? Part of the challenge of containing the coronavirus is that infected people can spread it before they begin to show symptoms — i.e., before they even know they’re sick. It’s why mask wearing and social distancing are important, and it also creates the need for quick, low-cost diagnostic technologies that don’t need to be administered by medical professionals.
How does it work? The test is multiplexed, meaning it collects numerous data points: The latest version, made from graphene and called SARS-CoV-2 RapidPlex, takes less than 10 minutes to detect in small volumes of saliva or blood the presence of the virus itself, plus antibodies the immune system has created to fight the virus and signs of inflammation that could indicate the severity of infection. Medical engineering professor Wei Gao, whose lab developed the sensor, said, “This is the only telemedicine platform I've seen that can give information about the infection in three types of data with a single sensor. In as little as a few minutes, we can simultaneously check these levels, so we get a full picture about the infection, including early infection, immunity and severity.”
What is it? Collaborating with colleagues around the globe, researchers at the University of Oxford developed a one-step, low-cost method for converting plastic waste into hydrogen gas.
Why does it matter? Difficult to recycle, discarded plastic is ending up in waterways around the world, in a growing environmental catastrophe. It’s good to be able to meaningfully reuse that waste — even better if it can be turned into hydrogen, a clean fuel that yields only water as a byproduct. Oxford chemistry professor Peter Edwards said the new technology “offers a potential route to the challenge of the plastic waste Armageddon, particularly in developing countries as one route to the hydrogen economy — effectively enabling them to leap-frog the sole use of fossil fuels.”
How does it work? After pulverizing plastic into particles, Edwards and colleagues mixed the particles with “a microwave-susceptor catalyst of iron oxide and aluminum oxide,” according to an Oxford news release. “The mixture was subjected to microwave treatment and yielded a large volume of hydrogen gas and a residue of carbonaceous materials, the bulk of which were identified as carbon nanotubes.” The method, which “demonstrates that over 97% of hydrogen in plastic can be extracted in a very short time, in a low-cost method with no CO2 burden,” is described further in Nature Catalysis.
What is it? Scientists from Queen Mary University of London, the University of Cambridge and Russia’s Institute for High Pressure Physics crunched some numbers and came up with the upper limit of how fast sound can travel: 36 kilometers, or 22 miles, per second.
Why does it matter? Sound travels differently than light, which moves fastest in a vacuum. By contrast, sound waves move faster through more rigid mediums: In part that’s why whales can communicate across long distances through water, and why diamonds efficiently convey sound. Cambridge materials science professor Chris Pickard said, “Sound waves in solids are already hugely important across many scientific fields. For example, seismologists use sound waves initiated by earthquakes deep in the earth interior to understand the nature of seismic events and the properties of earth composition. They’re also of interest to materials scientists because sound waves are related to important elastic properties, including the ability to resist stress.”
How does it work? The researchers calculated the limits based on two fundamental physical constants: the fine structure constant and the proton-to-electron mass ratio. The team used the constants to design an equation that would predict the speed of sound through various solids and liquids, predicting further that it would approach its theoretical limit in solid atomic hydrogen, which only exists in super-high-pressure atmospheres — like the core of Jupiter. The calculations are described further in Science Advances.
What is it? Researchers at the U.K.’s University of Birmingham used a type of wave more commonly associated with earthquakes to create “the first scaling law for touch sensitivity,” which could lead the way to new advances in virtual reality.
Why does it matter? Mathematician Tom Montenegro-Johnson, who led the research, said, “Touch is a primordial sense, as important to our ancient ancestors as it is to modern-day mammals, but it’s also one of the most complex and therefore least understood. While we have universal laws to explain sight and hearing, for example, this is the first time that we’ve been able to explain touch in this way.”
How does it work? Montenegro-Johnson and colleagues specifically studied Rayleigh waves, seismic waves that were thought to only travel along surfaces. The researchers discovered, though, that the waves travel through skin and bone and are felt by the body’s receptor cells: “Using mathematical modeling of these touch receptors, the researchers showed how the receptors were located at depths that allowed them to respond to Rayleigh waves. The interaction of these receptors with the Rayleigh waves will vary across species, but the ratio of receptor depth vs. wavelength remains the same, enabling the universal law to be defined.” The study is described further in Science Advances.