Tag Archives: Physics

New UN climate report is a ‘Code Red for Humanity’

By Reynard Loki – In a grim report released on August 9, the Intergovernmental Panel on Climate Change (IPCC) says that climate change was “unequivocally” caused by human activity, and that within two decades, rising temperatures will cause the planet to reach a significant turning point in global warming. The report’s authors—a group of the world’s top climate scientists convened by the United Nations (UN)—predict that by 2040, average global temperatures will be warmer than 1.5 degrees Celsius above pre-industrial levels, causing more frequent and intense heat waves, droughts and extreme weather events. UN Secretary-General António Guterres called the bleak findings a “code red for humanity.”

The report found global warming increasing at a faster rate than earlier predictions estimated. “It is unequivocal that human influence has warmed the atmosphere, ocean and land… [and] at a rate that is unprecedented in at least the last 2,000 years,” the report says. “Widespread and rapid changes in the atmosphere, ocean, cryosphere and biosphere have occurred.” Even if the world’s nations enacted sharp and stringent reductions in the emissions of greenhouse gases today, overall global warming is still estimated to rise around 1.5 degrees Celsius within the next 20 years. That means that the hotter, more dangerous future that scientists and the Paris climate agreement sought to avoid is now unavoidable.

Linda Mearns, a senior climate scientist at the US National Center for Atmospheric Research and one of the report’s co-authors, offered a stern warning: “It’s just guaranteed that it’s going to get worse,” she said, adding that there is “[n]owhere to run, nowhere to hide.” In an interview with the Hill, Kim Cobb, the lead author of the report’s first chapter, said, “We’re already reeling, clearly, from so many of these impacts that the report highlights, especially in the category of extremes that are gripping these headlines and causing so much damage, but of course the 1.5 degree C world is notably and discernibly worse.” more>

How to Build a Better Automotive Radar System

By John Blyler – Advanced driver assistance systems (ADAS) rely heavily on modern radar technology. And why not? Radar uses electromagnetic waves to sense the environment. It can operate over a long distance in poor visibility or inclement weather conditions. Designing automotive RF that accurately captures diverse traffic situations will be essential in making autonomous operations safe.

Radar systems are no newcomer to the automotive space. In the past, automotive radar was used in vehicles for basic operations such as automatic emergency braking (AEB) and adaptive cruise control (ACC), where the radar sensor only had to provide the vehicle with information relating to the distance and speed of the target in front of it.

However, recent trends to deploy a fully autonomous vehicle have increased the amount of information that a vehicle demands from the radar sensor. Specifically, after detecting a target, the host vehicle must determine several things, such as the distance to a target – be it another car, a person, a stationary object, or the like. The radar must also calculate how fast the target is approaching or departing; whether it is to the right, left, or straight ahead of the vehicle; on the road or above the ground; and the nature of the target, i.e., pedestrian or vehicle, for example.

Automotive radar technology can provide essential, real-time information to the vehicle’s onboard embedded computers and software algorithms to answer these questions by providing five-dimensional datasets: Range, Doppler, Azimuthal direction of arrival (DoA), Elevation direction of arrival (DoA), and Micro-Doppler.

As vehicles migrate from SAE level 1 to level 5 full autonomy, automotive radar technology will be used for far more than emergency braking and adaptive cruise control with ever-increasing reliability and accuracy demands. more>

Keep science irrational

By Michael Strevens – Modern science has a whole lot going for it that Ancient Greek or Chinese science did not: advanced technologies for observation and measurement, fast and efficient communication, and well-funded and dedicated institutions for research. It also has, many thinkers have supposed, a superior (if not always flawlessly implemented) ideology, manifested in a concern for objectivity, openness to criticism, and a preference for regimented techniques for discovery, such as randomized, controlled experimentation. I want to add one more item to that list, the innovation that made modern science truly scientific: a certain, highly strategic irrationality.

‘Experiment is the sole judge of scientific “truth”,’ declared the physicist Richard Feynman in 1963. ‘All I’m concerned with is that the theory should predict the results of measurements,’ said Stephen Hawking in 1994. And dipping back a little further in time, we find the 19th-century polymath John Herschel expressing the same thought: ‘To experience we refer, as the only ground of all physical enquiry.’ These are not just personal opinions or propaganda; the principle that only empirical evidence carries weight in scientific argument is widely enforced across the scientific disciplines by scholarly journals, the principal organs of scientific communication. Indeed, it is widely agreed, both in thought and in practice, that science’s exclusive focus on empirical evidence is its greatest strength.

et there is more than a whiff of dogmatism about this exclusivity. Feynman, Hawking, Herschel all insist on it: ‘the sole judge’; ‘all I’m concerned with’; ‘the only ground’. Are they, perhaps, protesting too much? What about other considerations widely considered relevant to assessing scientific hypotheses: theoretical elegance, unity, or even philosophical coherence? Except insofar as such qualities make themselves useful in the prediction and explanation of observable phenomena, they are ruled out of scientific debate, declared unpublishable. It is that unpublishability, that censorship, that makes scientific argument unreasonably narrow. It is what constitutes the irrationality of modern science – and yet also what accounts for its unprecedented success. more>

Universe in a bubble

Maybe we don’t have to speculate about what life is like inside a bubble. It might be the only cosmic reality we know.
By J Richard Gott – The explanation for the accelerating cosmic expansion, surprising as it was at first, was readily available from the theoretical toolbox of physicists. It traced back to an idea from Albert Einstein, called the cosmological constant. Einstein invented it in 1917, as part of a failed attempt to produce a static Universe based on his general theory of relativity. At that time, the data seemed to support such a model.

In 1922, the Russian mathematician Alexander Friedmann showed that relativity in its simplest form, without the cosmological constant, seemed to imply an expanding or contracting Universe. When Hubble’s observations showed conclusively that the Universe was expanding, Einstein abandoned the cosmological constant, but the possibility that it existed never went away.

Then the Belgian physicist Georges Lemaître showed that the cosmological constant could be interpreted in a physical way as the vacuum of empty space possessing a finite energy density accompanied by a negative pressure. That idea might sound rather bizarre at first. We are accustomed, after all, to thinking that the vacuum of empty space should have a zero energy density, since it has no matter in it. But suppose empty space had a finite but small energy density – there’s no inherent reason why such a thing could not be possible.

Negative pressure has a repulsive gravitational effect, but at the same time the energy itself has an attractive gravitational effect, since energy is equivalent to mass. (This is the relationship described by E=mc2, another implication of special relativity.) Operating in three directions – left-right, front-back, and up-down – the negative pressure creates repulsive effects three times as potent as the attractive effects of the vacuum energy, making the overall effect repulsive. We call this vacuum energy dark energy, because it produces no light. Dark energy is the widely accepted explanation for why the expansion rate of the Universe is speeding up.

Distant galaxies will flee from us because of the stretching of space between us and them. After a sufficient number of doublings, the space between them and us will be stretching so fast that their light will no longer be able to cross this ever-widening gap to reach us. Distant galaxies will fade from view and we will find ourselves seemingly alone in the visible Universe. more>

Updates from Georgia Tech

Brilliant Glow of Paint-On Semiconductors Comes from Ornate Quantum Physics
By Ben Brumfield – LED lights and monitors, and quality solar panels were born of a revolution in semiconductors that efficiently convert energy to light or vice versa. Now, next-generation semiconducting materials are on the horizon, and in a new study, researchers have uncovered eccentric physics behind their potential to transform lighting technology and photovoltaics yet again.

Comparing the quantum properties of these emerging so-called hybrid semiconductors with those of their established predecessors is about like comparing the Bolshoi Ballet to jumping jacks. Twirling troupes of quantum particles undulate through the emerging materials, creating, with ease, highly desirable optoelectronic (light-electronic) properties, according to a team of physical chemists led by researchers at the Georgia Institute of Technology.

These same properties are impractical to achieve in established semiconductors.

The particles moving through these new materials also engage the material itself in the quantum action, akin to dancers enticing the floor to dance with them. The researchers were able to measure patterns in the material caused by the dancing and relate them to the emerging material’s quantum properties and to energy introduced into the material.

These insights could help engineers work productively with the new class of semiconductors. more>

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Updates from Georgia Tech

Finally, a Robust Fuel Cell that Runs on Methane at Practical Temperatures
By Ben Brumfield – Fuel cells have not been particularly known for their practicality and affordability, but that may have just changed. There’s a new cell that runs on cheap fuel at temperatures comparable to automobile engines and which slashes materials costs.

Though the cell is in the lab, it has high potential to someday electrically power homes and perhaps cars, say the researchers at the Georgia Institute of Technology who led its development. In a new study in the journal Nature Energy the researchers detailed how they reimagined the entire fuel cell with the help of a newly invented fuel catalyst.

The catalyst has dispensed with high-priced hydrogen fuel by making its own out of cheap, readily available methane. And improvements throughout the cell cooled the seething operating temperatures that are customary in methane fuel cells dramatically, a striking engineering accomplishment. more>

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Updates from Georgia Tech

Looking Back in Time to Watch for a Different Kind of Black Hole
By John Toon – Black holes form when stars die, allowing the matter in them to collapse into an extremely dense object from which not even light can escape. Astronomers theorize that massive black holes could also form at the birth of a galaxy, but so far nobody has been able to look far enough back in time to observe the conditions creating these direct collapse black holes (DCBH).

The James Webb Space Telescope, scheduled for launch in 2021, might be able look far enough back into the early Universe to see a galaxy hosting a nascent massive black hole. Now, a simulation done by researchers at the Georgia Institute of Technology has suggested what astronomers should look for if they search the skies for a DCBH in its early stages.

DCBH formation would be initiated by the collapse of a large cloud of gas during the early formation of a galaxy, said John H. Wise, a professor in Georgia Tech’s School of Physics and the Center for Relativistic Astrophysics. But before astronomers could hope to catch this formation, they would have to know what to look for in the spectra that the telescope could detect, which is principally infrared.

Black holes take about a million years to form, a blip in galactic time. In the DCBH simulation, that first step involves gas collapsing into a supermassive star as much as 100,000 times more massive than our sun. The star then undergoes gravitational instability and collapses into itself to form a massive black hole. Radiation from the black hole then triggers the formation of stars over period of about 500,000 years, the simulation suggested. more>

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Anthropic arrogance

By David P Barash – Welcome to the ‘anthropic principle’, a kind of Goldilocks phenomenon or ‘intelligent design’ for the whole Universe. According to its proponents, the Universe is fine-tuned for human life.

The message is clearly an artificial one and not the result of random noise. Or maybe the Universe itself is alive, and the various physical and mathematical constants are part of its metabolism. Such speculation is great fun, but it’s science fiction, not science.

It should be clear at this point that the anthropic argument readily devolves – or dissolves – into speculative philosophy and even theology. Indeed, it is reminiscent of the ‘God of the gaps’ perspective, in which God is posited whenever science hasn’t (yet) provided an answer.

Calling upon God whenever there is a gap in our scientific understanding may be tempting, but it is not even popular among theologians, because as science grows, the gaps – and thus, God – shrinks. It remains to be seen whether the anthropic principle, in whatever form, succeeds in expanding our sense of ourselves beyond that illuminated by science. I wouldn’t bet on it. more>

Updates from Georgia Tech

Neuroscientists Team with Engineers to Explore how the Brain Controls Movement
By Carol Clark – Scientists have made remarkable advances into recording the electrical activity that the nervous system uses to control complex skills, leading to insights into how the nervous system directs an animal’s behavior.

“We can record the electrical activity of a single neuron, and large groups of neurons, as animals learn and perform skilled behaviors,” says Samuel Sober, an associate professor of biology at Emory University who studies the brain and nervous system. “What’s missing,” he adds, “is the technology to precisely record the electrical signals of the muscles that ultimately control that movement.”

The Sober lab is now developing that technology through a collaboration with the lab of Muhannad Bakir, a professor in Georgia Tech’s School of Electrical and Computer Engineering.

The technology will be used to help understand the neural control of many different skilled behaviors to potentially gain insights into neurological disorders that affect motor control.

“By combining expertise in the life sciences at Emory with the engineering expertise of Georgia Tech, we are able to enter new scientific territory,” Bakir says. “The ultimate goal is to make discoveries that improve the quality of life of people.” more>

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Updates from Georgia Tech

New Cell Manufacturing Research Facility will Change Approaches to Disease Therapies
By John Toon – The vision of making affordable, high-quality cell-based therapies available to hundreds of thousands of patients worldwide moved closer to reality June 6 with the dedication of a new cell manufacturing research facility at Georgia Tech aimed at changing the way we think about medical therapies.

The new Good Manufacturing Practice (GMP) like ISO 8 and ISO 7 compliant facility is part of the existing Marcus Center for Therapeutic Cell Characterization and Manufacturing (MC3M). The center was established in 2016 and made possible by a $15.75 million gift from philanthropist Bernie Marcus, with a $7.25 million investment from Georgia Tech and another $1 million from the Georgia Research Alliance.

MC3M is already helping researchers from Georgia Tech and partner organizations develop ways to provide therapeutic living cells of consistent quality in quantities large enough to meet the growing demands for the cutting-edge treatments. more>

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