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Posts Tagged ‘Physics

“Everything we know and love about the universe and all the laws of physics as they apply, apply to four percent of the universe”*…

 

dark matter

 

In 1969, the American astronomer Vera Rubin puzzled over her observations of the sprawling Andromeda Galaxy, the Milky Way’s biggest neighbour. As she mapped out the rotating spiral arms of stars through spectra carefully measured at the Kitt Peak National Observatory and the Lowell Observatory, both in Arizona, she noticed something strange: the stars in the galaxy’s outskirts seemed to be orbiting far too fast. So fast that she’d expect them to escape Andromeda and fling out into the heavens beyond. Yet the whirling stars stayed in place.

Rubin’s research, which she expanded to dozens of other spiral galaxies, led to a dramatic dilemma: either there was much more matter out there, dark and hidden from sight but holding the galaxies together with its gravitational pull, or gravity somehow works very differently on the vast scale of a galaxy than scientists previously thought.

Her influential discovery never earned Rubin a Nobel Prize, but scientists began looking for signs of dark matter everywhere, around stars and gas clouds and among the largest structures in the galaxies in the Universe. By the 1970s, the astrophysicist Simon White at the University of Cambridge argued that he could explain the conglomerations of galaxies with a model in which most of the Universe’s matter is dark, far outnumbering all the atoms in all the stars in the sky. In the following decade, White and others built on that research by simulating the dynamics of hypothetical dark matter particles on the not-so-userfriendly computers of the day.

But despite those advances, over the past half century, no one has ever directly detected a single particle of dark matter. Over and over again, dark matter has resisted being pinned down, like a fleeting shadow in the woods. Every time physicists have searched for dark matter particles with powerful and sensitive experiments in abandoned mines and in Antarctica, and whenever they’ve tried to produce them in particle accelerators, they’ve come back empty-handed. For a while, physicists hoped to find a theoretical type of matter called weakly interacting massive particles (WIMPs), but searches for them have repeatedly turned up nothing…

Dark matter is the most ubiquitous thing physicists have never found. Is it time to consider alternative explanations? “Does dark matter exist?

[image above: source]

* Neil deGrasse Tyson

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As we interrogate the invisible, we might recall that it was on this date in 1944 that one of the worst fire disasters in U.S. history occurred; the blaze broke out during an afternoon performance of the Ringling Bros. and Barnum & Bailey Circus that was attended by an estimated 7,000 people.  It killed 167 people; more than 700 were injured.

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Because of the paraffin wax waterproofing of the tent, the flames spread rapidly

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Emmett Kelly holding a water bucket on what became known as “the day the clowns cried

 

Written by LW

July 6, 2020 at 1:01 am

“Blessed be you, mighty matter”*…

 

anyon

The existence of anyons was inferred from quantum topology — the novel properties of shapes made by quantum systems

 

Every particle in the universe — from a cosmic ray to a quark — is either a fermion or a boson. These categories divide the building blocks of nature into two distinct kingdoms… or so we thought.  Now researchers have discovered the first examples of a third particle kingdom…

Anyons, as they’re known, don’t behave like either fermions or bosons; instead, their behavior is somewhere in the middle. In a recent paper published in Science, physicists have found the first experimental evidence that these particles don’t fit into either kingdom. “We had bosons and fermions, and now we’ve got this third kingdom,” said Frank Wilczek, a Nobel prize–winning physicist at the Massachusetts Institute of Technology. “It’s absolutely a milestone.”…

Rethinking the substance of reality…  More on these newly-identified building blocks at “‘Milestone’ Evidence for Anyons, a Third Kingdom of Particles.”

* “Blessed be you, mighty matter, irresistible march of evolution, reality ever newborn; you who, by constantly shattering our mental categories, force us to go ever further and further in our pursuit of the truth.”   — Pierre Teilhard de Chardin, Hymn of the Universe

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As we examine existence, we might spare a thought for Roger Bacon; he died on this date in 1292.  A philosopher and Franciscan friar, Bacon was one of the first to propose mathematics and experimentation as appropriate methods of science.  Working in mathematics, astronomy, physics, alchemy, and languages, he was particularly impactful in optics: he elucidated the principles of refraction, reflection, and spherical aberration, and described spectacles, which soon thereafter came into use.  He developed many mathematical results concerning lenses, proposed mechanically propelled ships, carriages, and flying machines, and used a camera obscura to observe eclipses of the Sun.  And he was the first European give a detailed description of the process of making gunpowder.

He began his career at Oxford, then lectured for a time at Paris, where his skills as a pedagogue earned him the title Doctor Mirabilis, or “wonderful teacher.”  He stopped teaching when he became a Franciscan.  But his scientific work continued, despite his Order’s restrictions on activity and publication, as Bacon enjoyed the protection and patronage of Pope Clement…  until, on Clement’s death, he was placed under house arrest in Oxford, where he continued his studies, but was unable to publish and communicate with fellow investigators.

Statue of Roger Bacon in the Oxford University Museum

 source

 

Written by LW

June 11, 2020 at 1:01 am

“Time … thou ceaseless lackey to eternity”*…

 

600BC-chronus-deity

Source art: Chronos and His Child by Giovanni Francesco Romanelli

 

The human mind has long grappled with the elusive nature of time: what it is, how to record it, how it regulates life, and whether it exists as a fundamental building block of the universe…

Quanta‘s fascinating timeline traces our evolving understanding of time through a history of observations in culture, physics, timekeeping, and biology: “Arrows of Time

* Shakespeare, The Rape of Lucrece

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As we try to Be Here Now, we might send amusingly insightful birthday greetings to Richard Philips Feynman; he was born on this date in 1918.  A theoretical physicist, Feynman was probably the most brilliant, influential, and iconoclastic figure in his field in the post-WW II era.

Richard Feynman was a once-in-a-generation intellectual. He had no shortage of brains. (In 1965, he won the Nobel Prize in Physics for his work on quantum electrodynamics.) He had charisma. (Witness this outtake [below] from his 1964 Cornell physics lectures [available in full here].) He knew how to make science and academic thought available, even entertaining, to a broader public. (We’ve highlighted two public TV programs hosted by Feynman here and here.) And he knew how to have fun. The clip above brings it all together.

– From Open Culture (where one can also find Feynman’s elegant and accessible 1.5 minute explanation of “The Key to Science.”)

 

Written by LW

May 11, 2020 at 1:01 am

“Real randomness requires an infinite amount of information”*…

 

the_quantum_random_number_generator_2_alt_1050x700

 

If you have ever tossed dice, whether in a board game or at the gambling table, you have created random numbers—a string of numbers each of which cannot be predicted from the preceding ones. People have been making random numbers in this way for millennia. Early Greeks and Romans played games of chance by tossing the heel bone of a sheep or other animal and seeing which of its four straight sides landed uppermost. Heel bones evolved into the familiar cube-shaped dice with pips that still provide random numbers for gaming and gambling today.

But now we also have more sophisticated random number generators, the latest of which required a lab full of laser equipment at the U.S. National Institute of Standards and Technology (NIST) in Boulder, CO. It relies on counterintuitive quantum behavior with an assist from relativity theory to make random numbers. This was a notable feat because the NIST team’s numbers were absolutely guaranteed to be random, a result never before achieved.

Why are random numbers worth so much effort? Random numbers are chaotic for a good cause. They are eminently useful, and not only in gambling. Since random digits appear with equal probabilities, like heads and tails in a coin toss, they guarantee fair outcomes in lotteries, such as those to buy high-value government bonds in the United Kingdom. Precisely because they are unpredictable, they provide enhanced security for the internet and for encrypted messages. And in a nod to their gambling roots, random numbers are essential for the picturesquely named “Monte Carlo” method that can solve otherwise intractable scientific problems…

Using entanglement to generate true mathematical randomness– and why that matters: “The Quantum Random Number Generator.”

* Tristan Perich

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As we leave it to chance, we might send learned birthday greetings to Athanasius Kircher; he was born on this date in 1602.  A scholar, he published over 40 works. perhaps most notably on most notably in comparative religion, geology, and medicine, but over a range so broad that he was frequently compared to Leonardo Da Vinci (who died on the date in 1519) and was dubbed “Master of a Hundred Arts.”

For a look at one of his more curious works, see “Wonder is the beginning of wisdom.” And his take on The Plague (through which he lived in Italy in 1656), see here.

220px-Athanasius_Kircher_(cropped) source

 

“Once we introduce the possibility of applying the quantum principle to the universe, we are forced to consider parallel universes”*…

 

antiverse

 

In the Antarctic, things happen at a glacial pace. Just ask Peter Gorham. For a month at a time, he and his colleagues would watch a giant balloon carrying a collection of antennas float high above the ice, scanning over a million square kilometres of the frozen landscape for evidence of high-energy particles arriving from space.

When the experiment returned to the ground after its first flight, it had nothing to show for itself, bar the odd flash of background noise. It was the same story after the second flight more than a year later.

While the balloon was in the sky for the third time, the researchers decided to go over the past data again, particularly those signals dismissed as noise. It was lucky they did. Examined more carefully, one signal seemed to be the signature of a high-energy particle. But it wasn’t what they were looking for. Moreover, it seemed impossible. Rather than bearing down from above, this particle was exploding out of the ground.

That strange finding was made in 2016. Since then, all sorts of suggestions rooted in known physics have been put forward to account for the perplexing signal, and all have been ruled out. What’s left is shocking in its implications. Explaining this signal requires the existence of a topsy-turvy universe created in the same big bang as our own and existing in parallel with it. In this mirror world, positive is negative, left is right and time runs backwards. It is perhaps the most mind-melting idea ever to have emerged from the Antarctic ice ­­– but it might just be true…

Strange particles observed by an experiment in Antarctica could be evidence of an alternative reality where everything is upside down: “We may have spotted a parallel universe going backwards in time.”

* Michio Kaku

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As we consider our alternatives, we might recall that it was on this date in 1912, in his “Manuscript on the Special Theory of Relativity,” that Einstein first identified the fourth dimension as time… or so it is widely accepted.  Some physicists believe that Einstein was making a subtler– and much more complicated– suggestion, “x4 = ict”: that the fourth dimension, not “physical” like the other three, but emergent (in a way “understandable” as time) as the fourth dimension expands from the other three at the rate of “c.”

Screen Shot 2020-04-12 at 1.59.50 PM source

 

 

Written by LW

April 15, 2020 at 1:01 am

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