Why Do Matter Particles Come in Threes? A Physics Titan Weighs In.



The universe has cooked up all sorts of bizarre and beautiful forms of matter, from blazing stars to purring cats, out of just three basic ingredients. Electrons and two types of quarks, dubbed “up” and “down,” mix in various ways to produce every atom in existence.

But puzzlingly, this family of matter particles — the up quark, down quark and electron — is not the only one. Physicists have discovered that they make up the first of three successive “generations” of particles, each heavier than the last. The second- and third-generation particles transform into their lighter counterparts too quickly to form exotic cats, but they otherwise behave identically. It’s as if the laws of nature were composed in triplicate. “We don’t know why,” said Heather Logan, a particle physicist at Carleton University.

In the 1970s, when physicists first worked out the Standard Model of particle physics — the still-reigning set of equations describing the known elementary particles and their interactions — they sought some deep principle that would explain why three generations of each type of matter particle exist. No one cracked the code, and the question was largely set aside. Now, though, the Nobel Prize-winning physicist Steven Weinberg, one of the architects of the Standard Model, has revived the old puzzle. Weinberg, who is 86 and a professor at the University of Texas, Austin, argued in a recent paper in the journal Physical Review D that an intriguing pattern in the particles’ masses could lead the way forward.

“Weinberg’s paper is a bit of lightning in the dark,” said Anthony Zee, a theoretical physicist at the University of California, Santa Barbara. “All of a sudden a titan in the field is suddenly working again on these problems.”

“I’m very happy to see that he thinks it’s important to revisit this problem,” said Mu-Chun Chen, a physicist at the University of California, Irvine. Many theorists are ready to give up, she said, but “we should still be optimistic.”

The Standard Model does not predict why each particle has the mass that it does. Physicists measure these values experimentally and manually plug the results into the equations. Measurements show that the minuscule electron weighs 0.5 megaelectron volts (MeV), while its second- and third-generation counterparts, called the muon and the tau particle, tip the scales at 105 and 1,776 MeV, respectively. Similarly, the first-generation up and down quarks are relative lightweights, while the “charm” and “strange” quarks comprising the second quark generation are middleweights, and the “top” and “bottom” quarks of the third generation are heavy, the top weighing a monstrous 173,210 MeV.

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Solved mystery shows 3 human species shared Africa 300K years ago



Scientists have solved a long-standing mystery over the age of a landmark skull found in 1921 in Zambia — the first fossil of an extinct human species discovered in Africa — in research with big implications for deciphering the origin of our own species.

The study published on Wednesday involved the so-called Broken Hill skull, also called the Kabwe skull in recognition of a nearby town, discovered by a Swiss miner working in the Broken Hill lead and zinc mine in what was then northern Rhodesia. Until now, scientists had been in the dark about how old it was, making it difficult to know its place on the human family tree.

But two sophisticated dating methods have determined the skull to be about 299,000 years old, plus or minus 25,000 years, said geochronologist Rainer Grün of Griffith University in Australia, lead author of the study published in the journal Nature. Some experts had hypothesized it was 500,000 years old.

This indicates the species represented by the skull was unlikely to have been a direct ancestor of Homo sapiens as some had thought. Our species first appeared more than 300,000 years ago in Africa, later spreading worldwide.

Scientists initially assigned the skull to a species they called Homo rhodesiensis. Most scientists now assign it to the species Homo heidelbergensis, which inhabited parts of Africa and Europe starting about 600,000 years ago.

Currently, there are three important issues on which there is scientific consensus but controversy among laypeople: climate change, biological evolution and childhood vaccination. On all three issues, prominent members of the Trump administration, including the president, have lined up against the conclusions of research.

This widespread rejection of scientific findings presents a perplexing puzzle to those of us who value an evidence-based approach to knowledge and policy.

Yet many science deniers do cite empirical evidence. The problem is that they do so in invalid, misleading ways. Psychological research illuminates these ways.

Proof exists in mathematics and logic but not in science. Research builds knowledge in progressive increments. As empirical evidence accumulates, there are more and more accurate approximations of ultimate truth but no final end point to the process. Deniers exploit the distinction between proof and compelling evidence by categorizing empirically well-supported ideas as “unproven.” Such statements are technically correct but extremely misleading, because there are no proven ideas in science, and evidence-based ideas are the best guides for action we have.

Boeing 787s must be turned off and on every 51 days to prevent 'misleading data' being shown to pilots



The US Federal Aviation Administration has ordered Boeing 787 operators to switch their aircraft off and on every 51 days to prevent what it called "several potentially catastrophic failure scenarios" – including the crashing of onboard network switches.

The airworthiness directive, due to be enforced from later this month, orders airlines to power-cycle their B787s before the aircraft reaches the specified days of continuous power-on operation.

The power cycling is needed to prevent stale data from populating the aircraft's systems, a problem that has occurred on different 787 systems in the past.

According to the directive itself, if the aircraft is powered on for more than 51 days this can lead to "display of misleading data" to the pilots, with that data including airspeed, attitude, altitude and engine operating indications. On top of all that, the stall warning horn and overspeed horn also stop working.

This alarming-sounding situation comes about because, for reasons the directive did not go into, the 787's common core system (CCS) – a Wind River VxWorks realtime OS product, at heart – stops filtering out stale data from key flight control displays. That stale data-monitoring function going down in turn "could lead to undetected or unannunciated loss of common data network (CDN) message age validation, combined with a CDN switch failure".

Solving the problem is simple: power the aircraft down completely before reaching 51 days. It is usual for commercial airliners to spend weeks or more continuously powered on as crews change at airports, or ground power is plugged in overnight while cleaners and maintainers do their thing.

Watch Ultra-Dense Tungsten Cube Vaporize Objects in Slow-Mo

Newton’s law of universal gravitation is merciless. Especially if you happen to be an object underneath a 42-pound, 4″ tungsten cube hurtling toward you from a third-story balcony. Watching a super-dense tungsten cube smash and vaporize objects after being dropped out of a third-story window, on the other hand, is nothing but enjoyable. And is a great opportunity for learning about physics!

William Osman and Allen Pan are behind this smashing little experiment, which was just released on Osman’s YouTube channel. Osman is a mechanical and electric engineer living in Ventura, California, and Pan is a “YouTuber, Maker, and Failed Mythbuster.”

It’s unclear why the pair of edutainment professionals decided to team up for this particular project, but considering the slow-motion video and white coats and over-the-shoulder shots of the duo watching just-recorded footage, we’re going to go ahead and say they were inspired by the Slow Mo Guys. Plus there are all those references.

...what enabled Homo erectus to evolve into Homo sapiens was its encounter with magic mushrooms and psilocybin, the psychedelic compound within them, on that evolutionary journey. He called this the Stoned Ape Hypothesis.

Whale sharks: Atomic tests solve age puzzle of world's largest fish



Data from atomic bomb tests conducted during the Cold War have helped scientists accurately age the world's biggest fish.

Whale sharks are large, slow moving and docile creatures that mainly inhabit tropical waters.

They are long-lived but scientists have struggled to work out the exact ages of these endangered creatures.

But using the world's radioactive legacy they now have a workable method that can help the species survival.

Whale sharks are both the biggest fish and the biggest sharks in existence.

Growing up to 18m in length, and weighing on average of about 20 tonnes, their distinctive white spotted colouration makes them easily recognisable.

These filter feeders live on plankton and travel long distances to find food.

They are very popular with tourists in many locations, often allowing divers to swim alongside them.

However, the species is now classified as endangered because of over-fishing in places like Thailand and the Philippines.

Much about the species remains a mystery, especially how to age them correctly.

Researchers say this is fundamental to understanding their growth rates - information that's considered crucial to saving the species in the long term.

To date, scientists have tried to count distinct lines in the vertebrae of dead whale sharks. These act like rings in a tree trunk, increasing as the animal gets older.

But scientists have been unsure about how often these rings can form and the reasons behind them.

Now researchers say they have come up with a much more accurate way of determining the whale sharks' true age.

From the late 1940s, several nations including the US, the Soviet Union, Great Britain, France and China conducted atomic bomb tests in different locations.

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This team managed to find two long-dead specimens stored in Pakistan and Taiwan.

The study indicated that these creatures do actually live an incredibly long time.

"The absolute longevity of these animals could be very, very old, possibly as much as 100-150 years old," said Dr Meekan.

"This has huge implications for the species. It suggests that these things are probably intensely vulnerable to over-harvesting."

Experiment finds that gravity still works down to 50 micrometers


Sensitive gravity test fails to find hidden dimension. Next: find old wardrobe.



Gravity is the weakest of the fundamental forces, but it's the only force that operates over very long distances. Hence, planets orbit stars, stars form galaxies, and galaxies cluster. Gravity also operates at the tiniest of scales, too, but its weakness makes it very hard to detect its influence. It's worth trying, though, as violations of the laws of gravity at very small scales would be good evidence for New Physics™. So physicists have been looking, though without much luck so far.
Searching for flaws in gravity

The force due to gravity reduces with the square of the distance. If you double the distance, the force is not halved but reduced to a quarter of its original value. This law, called an inverse square law, is based purely on geometry: we live in three spatial dimensions, and therefore the inverse square law holds. However, if the universe has more than three spatial dimensions, the inverse square law would break.

We know that over long distances—the Earth to the Moon, and the distances between stars—the inverse square law appears to be correct. At galactic and cosmological scales, the inverse square law also holds, with the caveat that dark matter and dark energy are required. You might think that what we call dark matter or dark energy would be potential evidence of extra dimensions, but it isn’t quite that simple. At these scales, the hidden dimension would have to be both large and unable to influence anything else, like photons. Since we also require consistency, and large hidden dimensions don’t appear to offer it at the moment, we are restricted to tiny hidden dimensions and changes to gravity at very small scales.

At very small scales—in the laboratory—verifying that gravity obeys the inverse square law is much more challenging. The force of gravity is so weak that stray electric fields (from the electrical lines in the wall, for instance) will overwhelm any signal.

Kristian G. Andersen, Andrew Rambaut, W. Ian Lipkin, Edward C. Holmes & Robert F. Garry
Nature Medicine (2020)

Since the first reports of novel pneumonia (COVID-19) in Wuhan, Hubei province, China, there has been considerable discussion on the origin of the causative virus, SARS-CoV-2 (also referred to as HCoV-19). Infections with SARS-CoV-2 are now widespread, and as of 11 March 2020, 121,564 cases have been confirmed in more than 110 countries, with 4,373 deaths.

SARS-CoV-2 is the seventh coronavirus known to infect humans; SARS-CoV, MERS-CoV and SARS-CoV-2 can cause severe disease, whereas HKU1, NL63, OC43 and 229E are associated with mild symptoms. Here we review what can be deduced about the origin of SARS-CoV-2 from comparative analysis of genomic data. We offer a perspective on the notable features of the SARS-CoV-2 genome and discuss scenarios by which they could have arisen. Our analyses clearly show that SARS-CoV-2 is not a laboratory construct or a purposefully manipulated virus.

Unusual ozone hole opens over the Arctic





Scientists using data from the Copernicus Sentinel-5P satellite have noticed a strong reduction of ozone concentrations over the Arctic. Unusual atmospheric conditions, including freezing temperatures in the stratosphere, have led ozone levels to plummet—causing a 'mini-hole' in the ozone layer.

The ozone layer is a natural, protective layer of gas in the stratosphere that shields life from the Sun's harmful ultraviolet radiation—which is associated with skin cancer and cataracts, as well as other environmental issues.

The 'ozone hole' most commonly referenced is the hole over Antarctica, forming each year during autumn.

In the past weeks, scientists from the German Aerospace Center (DLR) have noticed the unusually strong depletion of ozone over the northern polar regions. Using data from the Tropomi instrument on the Copernicus Sentinel-5P satellite, they were able to monitor this Arctic ozone hole form in the atmosphere.

In the past, mini ozone holes have occasionally been spotted over the North Pole, but the depletion over the Arctic this year is much larger compared to previous years.

A mutant bacterial enzyme that breaks down plastic bottles for recycling in hours has been created by scientists.

The enzyme, originally discovered in a compost heap of leaves, reduced the bottles to chemical building blocks that were then used to make high-quality new bottles. Existing recycling technologies usually produce plastic only good enough for clothing and carpets.

The company behind the breakthrough, Carbios, said it was aiming for industrial-scale recycling within five years. It has partnered with major companies including Pepsi and L’Oréal to accelerate development. Independent experts called the new enzyme a major advance.

https://www.theguardian.com/environment ... s-in-hours