(Roughly) Daily

Posts Tagged ‘Physics

“No structure, even an artificial one, enjoys the process of entropy. It is the ultimate fate of everything, and everything resists it.”*…

A 19th-century thought experiment that motivates physicists– and information scientists– still…

The universe bets on disorder. Imagine, for example, dropping a thimbleful of red dye into a swimming pool. All of those dye molecules are going to slowly spread throughout the water.

Physicists quantify this tendency to spread by counting the number of possible ways the dye molecules can be arranged. There’s one possible state where the molecules are crowded into the thimble. There’s another where, say, the molecules settle in a tidy clump at the pool’s bottom. But there are uncountable billions of permutations where the molecules spread out in different ways throughout the water. If the universe chooses from all the possible states at random, you can bet that it’s going to end up with one of the vast set of disordered possibilities.

Seen in this way, the inexorable rise in entropy, or disorder, as quantified by the second law of thermodynamics, takes on an almost mathematical certainty. So of course physicists are constantly trying to break it.

One almost did. A thought experiment devised by the Scottish physicist James Clerk Maxwell in 1867 stumped scientists for 115 years. And even after a solution was found, physicists have continued to use “Maxwell’s demon” to push the laws of the universe to their limits…

A thorny thought experiment has been turned into a real experiment—one that physicists use to probe the physics of information: “How Maxwell’s Demon Continues to Startle Scientists,” from Jonathan O’Callaghan (@Astro_Jonny)

* Philip K. Dick

###

As we reconsider the random, we might send carefully-calculated birthday greetings to Félix Édouard Justin Émile Borel; he was born on this date in 1871. A mathematician (and politician, who served as French Minister of the Navy), he is remembered for his foundational work in measure theory and probability. He published a number of research papers on game theory and was the first to define games of strategy.

But Borel may be best remembered for a thought experiment he introduced in one of his books, proposing that a monkey hitting keys at random on a typewriter keyboard will – with absolute certainty – eventually type every book in France’s Bibliothèque Nationale de France. This is now popularly known as the infinite monkey theorem.

source

“Human nature scares the hell out of me”*…

Henry Gee, paleontologist and senior editor of Nature, argues that we Homo sapiens are setting ourselves up for collapse. He cites population decline, a lack of genetic variation, our socioeconomic fixation on growth (and the way that that’s plundered the planet), among other factors. But he singles out one phenomenon in particular…

 The most insidious threat to humankind is something called “extinction debt.” There comes a time in the progress of any species, even ones that seem to be thriving, when extinction will be inevitable, no matter what they might do to avert it. The cause of extinction is usually a delayed reaction to habitat loss. The species most at risk are those that dominate particular habitat patches at the expense of others, who tend to migrate elsewhere, and are therefore spread more thinly. Humans occupy more or less the whole planet, and with our sequestration of a large wedge of the productivity of this planetwide habitat patch, we are dominant within it. H. sapiens might therefore already be a dead species walking.

The signs are already there for those willing to see them. When the habitat becomes degraded such that there are fewer resources to go around; when fertility starts to decline; when the birth rate sinks below the death rate; and when genetic resources are limited—the only way is down. The question is “How fast?”…

Eminently worth reading in full: “Humans Are Doomed to Go Extinct,” from @EndOfThePier in Scientific American (@sciam).

For chorus effect, see also “Headed for a sixth mass extinction? MIT geophysicist warns oceans are on the brink.”

And for a look at the (possible) aftermath, explore “The Earth After Humans.”

* Neil deGrasse Tyson

###

As we remind ourselves that “hope is a discipline,” we might send expansively-creative birthday greetings to Freeman Dyson; he was born on this date in 1923. A theoretical and mathematical physicist, mathematician, and statistician, he made material contributions– both processes and concepts— in quantum field theory, astrophysics, the mathematical formulation of quantum mechanics, condensed matter physics, nuclear physics, and engineering.

He will forever be remembered by SciFi fans as the originator of the idea of (what’s called) the Dyson Sphere (or Dyson Shell): he proposed that a highly advanced technological civilization would ultimately completely surround its host star with a huge shell to capture 100% of the useful radiant energy. This Dyson Sphere would have a gigantic cluster of artificial planetoids (“Dyson cloud”) with billions of billions of inhabitants who would make use of the energy captured by the Dyson Sphere. He also made the intriguing speculation that a Dyson Sphere viewed from other galaxies would have a highly distinctive, unnatural light. He suggested astronomers search for such tell-tale colored stars, which should signify advanced, intelligent life.

Dyson was skeptical of some climate science, believing that the advantages of global warming (e.g., greater crop yields) were underweighted and that climate models were underdeveloped (and thus untrustworthy). Still he sounded the alarm (in a way resonant with Gee’s, above) as to the possibility of humanity poisoning its own future:

In the near future, we will be in possession of genetic engineering technology which allows us to move genes precisely and massively from one species to another. Careless or commercially driven use of this technology could make the concept of species meaningless, mixing up populations and mating systems so that much of the individuality of species would be lost. Cultural evolution gave us the power to do this. To preserve our wildlife as nature evolved it, the machinery of biological evolution must be protected from the homogenizing effects of cultural evolution.

Unfortunately, the first of our two tasks, the nurture of a brotherhood of man, has been made possible only by the dominant role of cultural evolution in recent centuries. The cultural evolution that damages and endangers natural diversity is the same force that drives human brotherhood through the mutual understanding of diverse societies. Wells’s vision of human history as an accumulation of cultures, Dawkins’s vision of memes bringing us together by sharing our arts and sciences, Pääbo’s vision of our cousins in the cave sharing our language and our genes, show us how cultural evolution has made us what we are. Cultural evolution will be the main force driving our future…

Biological and Cultural Evolution– Six Characters in Search of an Author

source

“The threat of a pandemic is different from that of a nerve agent, in that a disease can spread uncontrollably, long after the first carrier has succumbed”*…

We were, of course, warned. As we do our best to digest the news of emergent new strains of the COVID-19 virus, a look back at Annie Sparrow‘s 2016 New York Review of Books essay on pandemics…

Pandemics—the uncontrolled spread of highly contagious diseases across countries and continents—are a modern phenomenon. The word itself, a neologism from Greek words for “all” and “people,” has been used only since the mid-nineteenth century. Epidemics—localized outbreaks of diseases—have always been part of human history, but pandemics require a minimum density of population and an effective means of transport. Since “Spanish” flu burst from the trenches of World War I in 1918, infecting 20 percent of the world’s population and killing upward of 50 million people, fears of a similar pandemic have preoccupied public health practitioners, politicians, and philanthropists. World War II, in which the German army deliberately caused malaria epidemics and the Japanese experimented with anthrax and plague as biological weapons, created new fears…

According to the doctor, writer, and philanthropist Larry Brilliant, “outbreaks are inevitable, pandemics are optional.”

Much of human history can be seen as a struggle for survival between humans and microbes. Pandemics are microbe offensives; public health measures are human defenses. Water purification, sanitation, and vaccination are crucial to our living longer, better, even taller lives. But these measures of mass salvation are not sexy. While we know prevention is better and considerably cheaper than cure, there is little financial reward or glory in it. Philanthropists prefer to build hospitals rather than pay community health workers. Pharmaceutical companies prefer the Western market to the distant and poor Global South where people cannot afford to buy treatments. Education is a powerful social vaccine against the ignorance that enables pathogens to flourish, but insufficient to overcome the corruption of public goods by private interests. The current enthusiasm for detecting the next panic-inducing pathogen should not divert resources and research from the perennial threats that we already have. We must resist the tendency of familiarity and past failures to encourage contempt and indifference…

An important (and in its time, sadly, prescient) read: “The Awful Diseases on the Way,” from @annie_sparrow in @nybooks.

See also “6 of the Worst Pandemics in History” (source of the image above) and “A history of pandemics.”

[TotH to MK]

Hannah Fry

###

As we prioritize preparation, we might recall that it was on this date in 1935 that physicist Erwin Schrödinger published his famous thought experiment– now known as “Schrödinger’s cat“– a paradox that illustrates the problem of the Copenhagen interpretation of quantum mechanics.

This image has an empty alt attribute; its file name is s-cat.jpg

source

“Men knew better than they realized, when they placed the abode of the gods beyond the reach of gravity”*…

In search of a theory of everything…

Twenty-five particles and four forces. That description — the Standard Model of particle physics — constitutes physicists’ best current explanation for everything. It’s neat and it’s simple, but no one is entirely happy with it. What irritates physicists most is that one of the forces — gravity — sticks out like a sore thumb on a four-fingered hand. Gravity is different.

Unlike the electromagnetic force and the strong and weak nuclear forces, gravity is not a quantum theory. This isn’t only aesthetically unpleasing, it’s also a mathematical headache. We know that particles have both quantum properties and gravitational fields, so the gravitational field should have quantum properties like the particles that cause it. But a theory of quantum gravity has been hard to come by.

In the 1960s, Richard Feynman and Bryce DeWitt set out to quantize gravity using the same techniques that had successfully transformed electromagnetism into the quantum theory called quantum electrodynamics. Unfortunately, when applied to gravity, the known techniques resulted in a theory that, when extrapolated to high energies, was plagued by an infinite number of infinities. This quantization of gravity was thought incurably sick, an approximation useful only when gravity is weak.

Since then, physicists have made several other attempts at quantizing gravity in the hope of finding a theory that would also work when gravity is strong. String theory, loop quantum gravity, causal dynamical triangulation and a few others have been aimed toward that goal. So far, none of these theories has experimental evidence speaking for it. Each has mathematical pros and cons, and no convergence seems in sight. But while these approaches were competing for attention, an old rival has caught up.

The theory called asymptotically (as-em-TOT-ick-lee) safe gravity was proposed in 1978 by Steven Weinberg. Weinberg, who would only a year later share the Nobel Prize with Sheldon Lee Glashow and Abdus Salam for unifying the electromagnetic and weak nuclear force, realized that the troubles with the naive quantization of gravity are not a death knell for the theory. Even though it looks like the theory breaks down when extrapolated to high energies, this breakdown might never come to pass. But to be able to tell just what happens, researchers had to wait for new mathematical methods that have only recently become available…

For decades, physicists have struggled to create a quantum theory of gravity. Now an approach that dates to the 1970s is attracting newfound attention: “Why an Old Theory of Everything Is Gaining New Life,” from @QuantaMagazine.

* Arthur C. Clarke, 2010: Odyssey Two

###

As we unify, we might pause to remember Sir Arthur Stanley Eddington, OM, FRS; he died in this date in 1944.  An astrophysicist, mathematician, and philosopher of science known for his work on the motion, distribution, evolution and structure of stars, Eddington is probably best remembered for his relationship to Einstein:  he was, via a series of widely-published articles, the primary “explainer” of Einstein’s Theory of General Relativity to the English-speaking world; and he was, in 1919, the leader of the experimental team that used observations of a solar eclipse to confirm the theory.

 source

“The past, like the future, is indefinite and exists only as a spectrum of possibilities”*…

A recent paper by Robert Lanza and others suggests that physical reality isn’t independent of us, “objective,” but is the product of networks of observers…

Is there physical reality that is independent of us? Does objective reality exist at all? Or is the structure of everything, including time and space, created by the perceptions of those observing it? Such is the groundbreaking assertion of a new paper published in the Journal of Cosmology and Astroparticle Physics.

The paper’s authors include Robert Lanza, a stem cell and regenerative medicine expert, famous for the theory of biocentrism, which argues that consciousness is the driving force for the existence of the universe. He believes that the physical world that we perceive is not something that’s separate from us but rather created by our minds as we observe it. According to his biocentric view, space and time are a byproduct of the “whirl of information” in our head that is weaved together by our mind into a coherent experience.

His new paper, co-authored by Dmitriy Podolskiy and Andrei Barvinsky, theorists in quantum gravity and quantum cosmology, shows how observers influence the structure of our reality.

According to Lanza and his colleagues, observers can dramatically affect “the behavior of observable quantities” both at microscopic and massive spatiotemporal scales. In fact, a “profound shift in our ordinary everyday worldview” is necessary, wrote Lanza in an interview with Big Think. The world is not something that is formed outside of us, simply existing on its own. “Observers ultimately define the structure of physical reality itself,” he stated.

How does this work? Lanza contends that a network of observers is necessary and is “inherent to the structure of reality.” As he explains, observers — you, me, and anyone else — live in a quantum gravitational universe and come up with “a globally agreed-upon cognitive model” of reality by exchanging information about the properties of spacetime. “For, once you measure something,” Lanza writes, “the wave of probability to measure the same value of the already probed physical quantity becomes ‘localized’ or simply ‘collapses.’” That’s how reality comes to be consistently real to us all. Once you keep measuring a quantity over and over, knowing the result of the first measurement, you will see the outcome to be the same.

“Similarly, if you learn from somebody about the outcomes of their measurements of a physical quantity, your measurements and those of other observers influence each other ‒ freezing the reality according to that consensus,” added Lanza, explaining further that “a consensus of different opinions regarding the structure of reality defines its very form, shaping the underlying quantum foam,” explained Lanza.

In quantum terms, an observer influences reality through decoherence, which provides the framework for collapsing waves of probability, “largely localized in the vicinity of the cognitive model which the observer builds in their mind throughout their lifespan,” he added.

Lanza says, “The observer is the first cause, the vital force that collapses not only the present, but the cascade of spatiotemporal events we call the past. Stephen Hawking was right when he said: ‘The past, like the future, is indefinite and exists only as a spectrum of possibilities.’”

Could an artificially intelligent entity without consciousness be dreaming up our world? Lanza believes biology plays an important role, as he explains in his book The Grand Biocentric Design: How Life Creates Reality, which he co-authored with the physicist Matej Pavsic.

While a bot could conceivably be an observer, Lanza thinks a conscious living entity with the capacity for memory is necessary to establish the arrow of time. “‘A brainless’ observer does not experience time and/or decoherence with any degree of freedom,” writes Lanza. This leads to the cause and effect relationships we can notice around us. Lanza thinks that “we can only say for sure that a conscious observer does indeed collapse a quantum wave function.”…

Another key aspect of their work is that it resolves “the exasperating incompatibility between quantum mechanics and general relativity,” which was a sticking point even for Albert Einstein.

The seeming incongruity of these two explanations of our physical world — with quantum mechanics looking at the molecular and subatomic levels and general relativity at the interactions between massive cosmic structures like galaxies and black holes — disappears once the properties of observers are taken into account.

While this all may sound speculative, Lanza says their ideas are being tested using Monte Carlo simulations on powerful MIT computer clusters and will soon be tested experimentally.

Is the physical universe independent from us, or is it created by our minds? “Is human consciousness creating reality?@RobertLanza

We might wonder, if this is so, how reality emerged at all. Perhaps one possibility is implied in “Consciousness was upon him before he could get out of the way.”

* Stephen Hawking

###

As we conjure with consciousness, we might recall that it was on this date in 1908 (the same year that he was awarded the Nobel Prize in Physics) that Ernest Rutherford announced in London that he had isolated a single atom of matter. The following year, he, Hans Geiger (later of “counter” fame), and Ernest Marsden conducted the “Gold Foil Experiment,” the results of which replaced J. J. Thomson‘s “Plum Pudding Model” of the atom with what became known as the “Rutherford Model“: a very small charged nucleus, containing much of the atom’s mass, orbited by low-mass electrons.

source

%d bloggers like this: