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ASTROPHYSICS

Why physicists are determined to prove Galileo and Einstein wrong | Live Science

In the 17th century, famed astronomer and physicist Galileo Galilei is said to have climbed to the top of the Tower of Pisa and dropped two different-sized cannonballs. He was trying to demonstrate his theory — which Albert Einstein later updated and added to his theory of relativity — that objects fall at the same rate regardless of their size.

Now, after spending two years dropping two objects of different mass into a free fall in a satellite, a group of scientists has concluded that Galileo and Einstein were right: The objects fell at a rate that was within two-trillionths of a percent of each other, according to a new study.

This effect has been confirmed time and time again, as has Einstein’s theory of relativity — yet scientists still aren’t convinced that there isn’t some kind of exception somewhere. “Scientists have always had a difficult time actually accepting that nature should behave that way,” said senior author Peter Wolf, research director at the French National Center for Scientific Research’s Paris Observatory.

That’s because there are still inconsistencies in scientists’ understanding of the universe.

“Quantum mechanics and general relativity, which are the two basic theories all of physics is built on today …are still not unified,” Wolf told Live Science. What’s more, although scientific theory says the universe is made up mostly of dark matter and dark energy, experiments have failed to detect these mysterious substances.

“So, if we live in a world where there’s dark matter around that we can’t see, that might have an influence on the motion of [objects],” Wolf said. That influence would be “a very tiny one,” but it would be there nonetheless.

So, if scientists see test objects fall at different rates, that “might be an indication that we’re actually looking at the effect of dark matter,” he added.

Wolf and an international group of researchers — including scientists from France’s National Center for Space Studies and the European Space Agency — set out to test Einstein and Galileo’s foundational idea that no matter where you do an experiment, no matter how you orient it and what velocity you’re moving at through space, the objects will fall at the same rate.

The researchers put two cylindrical objects — one made of titanium and the other platinum — inside each other and loaded them onto a satellite. The orbiting satellite was naturally “falling” because there were no forces acting on it, Wolf said.

They suspended the cylinders within an electromagnetic field and dropped the objects for 100 to 200 hours at a time.

From the forces the researchers needed to apply to keep the cylinders in place inside the satellite, the team deduced how the cylinders fell and the rate at which they fell, Wolf said.

And, sure enough, the team found that the two objects fell at almost exactly the same rate, within two-trillionths of a percent of each other. That suggested Galileo was correct. What’s more, they dropped the objects at different times during the two-year experiment and got the same result, suggesting Einstein’s theory of relativity was also correct.

Their test was an order of magnitude more sensitive than previous tests. Even so, the researchers have published only 10% of the data from the experiment, and they hope to do further analysis of the rest.

Not satisfied with this mind-boggling level of precision, scientists have put together several new proposals to do similar experiments with two orders of magnitude greater sensitivity, Wolf said.

Also, some physicists want to conduct similar experiments at the tiniest scale, with individual atoms of different types, such as rubidium and potassium, he added.

The findings were published Dec. 2 in the journal Physical Review Letters.

Source: Why physicists are determined to prove Galileo and Einstein wrong | Live Science






 

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ASTROPHYSICS

Mysterious particles spewing from Antarctica defy physics | Live Science

By Rafi Letzter – Staff Writer 1/24/2020

What’s making these things fly out of the frozen continent?

Our best model of particle physics is bursting at the seams as it struggles to contain all the weirdness in the universe. Now, it seems more likely than ever that it might pop, thanks to a series of strange events in Antarctic.

The death of this reigning physics paradigm, the Standard Model, has been predicted for decades. There are hints of its problems in the physics we already have. Strange results from laboratory experiments suggest flickers of ghostly new species of neutrinos beyond the three described in the Standard Model.

And the universe seems full of dark matter that no particle in the Standard Model can explain.

But recent tantalizing evidence might one day tie those vague strands of data together: Three times since 2016, ultra-high-energy particles have blasted up through the ice of Antarctica, setting off detectors in the Antarctic Impulsive Transient Antenna (ANITA) experiment, a machine dangling from a NASA balloon far above the frozen surface.

As Live Science reported in 2018, those events — along with several additional particles detected later at the buried Antarctic neutrino observatory IceCube — don’t match the expected behavior of any Standard Model particles. The particles look like ultra high-energy neutrinos. But ultra high-energy neutrinos shouldn’t be able to pass through the Earth. That suggests that some other kind of particle — one that’s never been seen before — is flinging itself into the cold southern sky.

Now, in a new paper, a team of physicists working on IceCube have cast heavy doubt on one of the last remaining Standard Model explanations for these particles: cosmic accelerators, giant neutrino guns hiding in space that would periodically fire intense neutrino bullets at Earth.

A collection of hyperactive neutrino guns somewhere in our northern sky could have blasted enough neutrinos into Earth that we’d detect particles shooting out of the southern tip of our planet. But the IceCube researchers didn’t find any evidence of that collection out there, which suggests new physics must be needed to explain the mysterious particles.

To understand why, it’s important to know why these mystery particles are so unsettling for the Standard Model.

Neutrinos are the faintest particles we know about; they’re difficult to detect and nearly massless. They pass through our planet all the time — mostly coming from the sun and rarely, if ever, colliding with the protons, neutrons and electrons that make up our bodies and the dirt beneath our feet.

But ultra-high-energy neutrinos from deep space are different from their low-energy cousins. Much rarer than low-energy neutrinos, they have wider “cross sections,” meaning they’re more likely to collide with other particles as they pass through them.

The odds of an ultra-high-energy neutrino making it all the way through Earth intact are so low that you’d never expect to detect it happening. That’s why the ANITA detections were so surprising: It was as if the instrument had won the lottery twice, and then IceCube had won it a couple more times as soon as it started buying tickets.

And physicists know how many lottery tickets they had to work with. Many ultra-high-energy cosmic neutrinos come from the interactions of cosmic rays with the cosmic microwave background (CMB), the faint afterglow of the Big Bang. Every once in a while, those cosmic rays interact with the CMB in just the right way to fire high-energy particles at Earth.

This is called the “flux,” and it’s the same all over the sky. Both ANITA and IceCube have already measured what the cosmic neutrino flux looks like to each of their sensors, and it just doesn’t produce enough high-energy neutrinos that you’d expect to detect a neutrino flying out of Earth at either detector even once.

“If the events detected by ANITA belong to this diffuse neutrino component, ANITA should have measured many other events at other elevation angles,” said Anastasia Barbano, a University of Geneva physicist who works on IceCube.

But in theory, there could have been  ultra-high-energy neutrino sources beyond the sky-wide flux, Barbano told Live Science: those neutrino guns, or cosmic accelerators.

“If it is not a matter of neutrinos produced by the interaction of ultra-high-energy cosmic rays with the CMB, then the observed events can be either neutrinos produced by individual cosmic accelerators in a given time interval” or some unknown Earthly source, Barbano said.

Blazars, active galactic nuclei, gamma-ray bursts, starburst galaxies, galaxy mergers, and magnetized and fast-spinning neutron stars are all good candidates for those sorts of accelerators, she said. And we know that cosmic neutrino accelerators do exist in space;  in 2018, IceCube tracked a high-energy neutrino back to a blazar, an intense jet of particles coming from an active black hole at the center of a distant galaxy.

ANITA picks up only the most extreme high-energy neutrinos, Barbano said, and if the upward-flying particles were cosmic-accelerator-boosted neutrinos from the Standard Model — most likely tau neutrinos — then the beam should have come with a shower of lower-energy particles that would have tripped IceCube’s lower-energy detectors.

“We looked for events in seven years of IceCube data,” Barbano said — events that matched the angle and length of the ANITA detections, which you’d expect to find if there were a significant battery of cosmic neutrino guns out there firing at Earth to produce these up-going particles. But none turned up.

Their results don’t completely eliminate the possibility of an accelerator source out there. But they do “severely constrain” the range of possibilities, eliminating all of the most plausible scenarios involving cosmic accelerators and many less-plausible ones.

“The message we want to convey to the public is that a Standard Model astrophysical explanation does not work no matter how you slice it,” Barbano said.

Researchers don’t know what’s next. Neither ANITA nor IceCube is an ideal detector for the needed follow-up searches, Barbano said, leaving the researchers with very little data on which to base their assumptions about these mysterious particles. It’s a bit like trying to figure out the picture on a giant jigsaw puzzle from just a handful of pieces.

Right now, many possibilities seem to fit the limited data, including a fourth species of “sterile” neutrino outside the Standard Model and a range of theorized types of dark matter. Any of these explanations would be revolutionary. But none is strongly favored yet.

“We have to wait for the next generation of neutrino detectors,” Barbano said.

The paper has not yet been peer reviewed and was published January 8 in the arXiv database.

Source: Mysterious particles spewing from Antarctica defy physics | Live Science






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ASTROPHYSICS

Alien Life Could Be Hiding Out on Far Fewer Planets Than We Thought

Alien Life Could Be Hiding Out on Far Fewer Planets Than We Thought

By Laura Geggel, Associate Editor | June 10, 2019

Where is complex alien life hanging out in the universe? Likely not on planets stewing in toxic gases, according to a new study that dramatically reduces the number of worlds where scientists will have the best luck finding ET.

In the past, researchers defined the “habitable zone” based on the distance between the planet and its star; planets that, like Earth, orbit at just the right distance to accommodate temperatures in which liquid water could exist on the planetary surface would be considered “habitable.” But while this definition works for basic, single-celled microbes, it doesn’t work for complex creatures, such as animals ranging from sponges to humans, the researchers said.

When these extra parameters — needed for complex creatures to exist — are taken into account, this habitable zone shrinks substantially, the researchers said. For instance, planets with high levels of toxic gases, such as carbon dioxide and carbon monoxide, would drop off the master list.

“This is the first time the physiological limits of life on Earth have been considered to predict the distribution of complex life elsewhere in the universe,” study co-researcher Timothy Lyons, a distinguished professor of biogeochemistry and director of the Alternative Earths Astrobiology Center at the University of California, Riverside (UCR), said in a statement.

To investigate, Lyons and his colleagues created a computer model of the atmospheric climate and photochemistry (a field that analyzes how different chemicals behave under visible or ultraviolet light) on a range of planets. The researchers began by looking at predicted levels of carbon dioxide, a gas that’s deadly at high levels but is also needed to keep temperatures above freezing (thanks to the greenhouse effect) on planets that orbit far from their host stars.

“To sustain liquid water at the outer edge of the conventional habitable zone, a planet would need tens of thousands of times more carbon dioxide than Earth has today,” study lead researcher Edward Schwieterman, a NASA postdoctoral fellow working with Lyons, said in the statement. “That’s far beyond the levels known to be toxic to human and animal life on Earth.

“Once carbon dioxide toxicity is factored into the equation, the traditional habitable zone for simple animal life is sliced in two, the researchers said. For complex life like humans, which is more sensitive to high levels of carbon dioxide, this safe zone shrinks to less than a third of the traditional area, the researchers found.

Complex life (blue) will likely be located in a so-called habitable zone that has the potential for liquid water. Other zones aren’t a promising in the search for life, including regions with toxic buildup of carbon dioxide (yellow) and carbon monoxide (red). These likely uninhabitable zones include exoplanets such as Proxima Centauri b and the TRAPPIST-1 planets e, f and g (black dots).

Under the new parameters, some stars have no safe-for-life zone; that includes Proxima Centauri and TRAPPIST-1, two of the sun’s closest neighbors. That’s because planets around these suns likely have high concentrations of carbon monoxide, the researchers said. Carbon monoxide can bind to hemoglobin in animal blood, and even small amounts of it can be deadly. (Conversely, another recent study argued that carbon monoxide might be a sign of extraterrestrial life, but as Schwieterman put it, “these [planets] would certainly not be good places for human or animal life as we know it on Earth.”)

The new guidelines may help researchers trim the number of planets where signs of alien life look promising, a boon to the field, given that there are almost 4,000 confirmed planets out there that orbit stars other than the sun.

“Our discoveries provide one way to decide which of these myriad planets we should observe in more detail,” study co-researcher Christopher Reinhard, a former UCR graduate student who is now an assistant professor of Earth and atmospheric sciences at the Georgia Institute of Technology, said in the statement. “We could identify otherwise-habitable planets with carbon dioxide or carbon monoxide levels that are likely too high to support complex life.”

The study was published online today (June 10) in The Astrophysical Journal.

Source: Alien Life Could Be Hiding Out on Far Fewer Planets Than We Thought






 

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Stephen Hawking Was Right: Black Holes Can Evaporate, Weird New Study Shows

Stephen Hawking Was Right: Black Holes Can Evaporate, Weird New Study Shows

By Meredith Fore, Live Science Contributor | June 10, 2019

Stephen Hawking made one of his most famous predictions: that black holes eventually evaporate entirely.

According to Hawking’s theory, black holes are not perfectly “black” but instead actually emit particles. This radiation, Hawking believed, could eventually siphon enough energy and mass away from black holes to make them disappear. The theory is widely assumed to be true but was once thought nearly impossible to prove.

For the first time, however, physicists have shown this elusive Hawking radiation — at least in a lab. Though Hawking radiation is too faint to be detected in space by our current instruments, physicists have now seen this radiation in a black hole analog created using sound waves and some of the coldest, strangest matter in the universe. Black holes exert such an incredibly powerful gravitational force that even a photon, which travels at the speed of light, could not escape. While the vacuum of space is generally thought of as empty, the uncertainty of quantum mechanics dictates that a vacuum is instead teeming with virtual particles that flit in and out of existence in matter-antimatter pairs. (Antimatter particles have the same mass as their matter counterparts, but opposite electrical charge.)

Normally, after a pair of virtual particles appears, they immediately annihilate each other. Next to a black hole, however, the extreme forces of gravity instead pull the particles apart, with one particle absorbed by the black hole as the other shoots off into space. The absorbed particle has negative energy, which reduces the black hole’s energy and mass. Swallow enough of these virtual particles, and the black hole eventually evaporates. The escaping particle becomes known as Hawking radiation.

This radiation is weak enough that it’s impossible right now for us to observe it in space, but physicists have thought up very creative ways to measure it in a lab.

Physicist Jeff Steinhauer and his colleagues at the Technion – Israel Institute of Technology in Haifa used an extremely cold gas called a Bose-Einstein condensate to model the event horizon of a black hole, the invisible boundary beyond which nothing can escape. In a flowing stream of this gas, they placed a cliff, creating a “waterfall” of gas; when the gas flowed over the waterfall, it turned enough potential energy into kinetic energy to flow faster than the speed of sound.

Instead of matter and antimatter particles, the researchers used pairs of phonons, or quantum sound waves, in the gas flow. The phonon on the slow side could travel against the flow of the gas, away from the waterfall, while the phonon on the fast side could not, trapped by the “black hole” of supersonic gas.

“It’s like if you were trying to swim against a current that was going faster than you could swim,” Steinhauer told Live Science. “You’d feel like you were going forward, but you were really going back. And that’s analogous to a photon in a black hole trying to get out of the black hole but being pulled by gravity the wrong way.”

Hawking predicted that the radiation of emitted particles would be in a continuous spectrum of wavelengths and energies. He also said that it could be described by a single temperature that was dependent only on the mass of the black hole. The recent experiment confirmed both of these predictions in the sonic black hole.

“These experiments are a tour de force,” Renaud Parentani, a theoretical physicist at Laboratoire de Physique Théorique of Paris-Sud University, told Live Science. Parentani also studies analog black holes but from a theoretical angle; he was not involved in the new study. “It’s a very precise experiment. From the experimental side, Jeff [Steinhauer] is really, at the moment, the world-leading expert of using cold atoms to probe black hole physics.”

Parentani, however, emphasized that this study is “one step along a long process.” In particular, this study did not show the phonon pairs being correlated on the quantum level, which is another important aspect of Hawking’s predictions.

“The story will continue,” said Parentani. “It is not at all the end.”

Source: Stephen Hawking Was Right: Black Holes Can Evaporate, Weird New Study






 

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‘God Plays Dice with the Universe,’ Einstein Writes in Letter About His Qualms with Quantum Theory

‘God Plays Dice with the Universe,’ Einstein Writes in Letter About His Qualms with Quantum Theory

By Mindy Weisberger, Senior Writer | June 12, 2019

In a letter that Albert Einstein wrote in 1945, the famous physicist sketched two diagrams demonstrating a novel approach to the thought experiment called the Einstein-Podolsky-Rosen (EPR) paradox.

Three letters written by Albert Einstein in 1945 are up for auction and offer an intriguing glimpse into the renowned physicist’s criticisms of how scientists were interpreting physics at the quantum level.

The letters, which were addressed to Caltech theoretical physicist Paul Epstein, describe Einstein’s qualms about quantum theory, which he called “incomplete” in one letter.

Another letter details the thought experiment that led to a quantum concept known as “spooky action at a distance” — when separated particles behave as if they were linked. The letters — eight pages of German writing and hand-drawn diagrams — will hit the auction block at Christie’s in New York today (June 12) at 2 p.m. ET, as part of the “Fine Printed Books and Manuscripts Including Americana” auction.

Einstein’s words in the letters demonstrate his fraught relationship with quantum physics, or the theories that describe the world of the very small (atoms and the subatomic particles inside them). For decades, he famously clashed with physicist Niels Bohr, whose views on the workings of the quantum world stated that particles behave differently when they are observed.

This introduced a fundamental element of uncertainty into the behavior of quantum particles; Einstein soundly rejected this perspective. Instead, Einstein argued that the rules for even tiny particles must be consistent whether the particles were observed or not.

“God tirelessly plays dice”

Einstein described his “private opinion” of quantum physics in one of the 1945 letters by referencing a phrase that he had already made famous: “God does not play dice with the universe.” In the letter, he wrote: “God tirelessly plays dice under laws which he has himself prescribed.” This variation clarified his argument that quantum particles must adhere to certain rules that don’t change randomly, and that the quantum world required better explanations for particle behavior, according to the item description.

While Einstein admitted in the letter that quantum theory in its present form was “a highly successful experiment,” he added that it had been undertaken “with inadequate means.”

In another letter written on Nov. 8, 1945, Einstein maps the origins of his thought experiment behind quantum entanglement, using text and diagrams to explain how he first imagined it. Einstein presented this idea in a paper published in 1935; the concept — co-authored with Boris Podolsky and Nathan Rosen — became known as the Einstein-Podolsky-Rosen (EPR) paradox, or spooky action at a distance, according to the American Physical Society.

Einstein and his colleagues meant for this paradox to demonstrate inherent flaws in perceptions of the quantum world. When Epstein responded to Einstein’s Nov. 8 letter with skepticism, Einstein reworked the EPR paradox, sending another version of the thought experiment in a letter dated Nov. 28, 1945.

He concluded the letter by reiterating his long-held criticism of the idea that the quantum realm couldn’t be described definitively, saying “it is this view against which my instinct revolts.”

However, recent experiments have suggested that despite Einstein’s protestations, the behavior of particles at the quantum level is likely influenced by randomness after all.

Together, the letters are expected to fetch more than $200,000 at the auction, according to the Christie’s website.

Source: ‘God Plays Dice with the Universe,’ Einstein Writes in Letter About His Qualms with Quantum Theory






 

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World’s Largest Atom Smasher May Have Just Found Evidence for Why Our Universe Exists

Physicists have observed a difference in the decay of particles containing the charm quark and its antiparticle, perhaps helping to explain why matter exists at all.

Every particle of matter has an antiparticle, which is identical in mass but with an opposite electrical charge. When matter and antimatter meet, they annihilate one another. That’s a problem. The Big Bang should have created an equivalent amount of matter and antimatter, and all of those particles should have destroyed each other rapidly, leaving nothing behind but pure energy. [Strange Quarks and Muons, Oh My! Nature’s Tiniest Particles Dissected]

Clearly, that didn’t happen. Instead, about 1 in a billion quarks (the elementary particles that make up protons and neutrons) survived. Thus, the universe exists. What that means is that particles and antiparticles must not behave entirely identically, Stone told Live Science. They should instead decay at slightly different rates, allowing for an imbalance between matter and antimatter. Physicists call that difference in behavior the charge-parity (CP) violation.

The notion of the CP violation came from Russian physicist Andrei Sakharov, who proposed it in 1967 as an explanation for why matter survived the Big Bang.

“This is one of the criteria necessary for us to exist,” Stone said, “so it’s kind of important to understand what the origin of CP violation is.”

There are six different types of quarks, all with their own properties: up and down, top and bottom and charm and strange. In 1964, physicists first observed the CP violation in real life in strange quarks. In 2001, they saw it happen with particles containing bottom quarks. (Both discoveries led to Nobel prizes for the researchers involved.)

Physicists had long theorized that it happened with particles containing charm quarks, too, but no one had ever seen it.

FINISH READING: World’s Largest Atom Smasher May Have Just Found Evidence for Why Our Universe Exists


 





 

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On Earth As In The Heavens

DID YOU KNOW…

(12). “Of course, not all things and phenomena in the cosmos have counterparts on Earth…What matters is the universality of the physical laws that describe them.”

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with Neil Degrasse Tyson






 

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Microwave ovens essentially don’t heat food; they heat the water in the food

DID YOU KNOW…

(11). “…water is the most common ingredient in food, and microwave ovens primarily heat water.”

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Universality Of Physical Laws

DID YOU KNOW…

(10). “…if we land on another planet with a thriving alien civilization, they will be running on the same laws that we discovered and tested here on Earth – even if the aliens harbor different social and political beliefs.”

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Universe invisible beyond spherical edge

DID YOU KNOW…

(8). “…there is a distance in every direction from us where the recession velocity for a galaxy equals the speed of light. At this distance and beyond, light from all luminous objects loses all its energy before reaching us. The universe beyond this spherical edge is thus rendered invisible and, as far as we know, unknowable.”

(9). “Among all constants, the speed of light is the most famous. No matter how fast you go, you will never overtake a beam of light.”

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Universe Had A Beginning after all

DID YOU KNOW…

 

(7). “What we do know, and what we can assert, without hesitation, is that the universe had a beginning. The universe continues to evolve. And yes, every one of our body’s atoms is traceable to the big bang and to the thermo-nuclear furnaces within high mass stars that exploded more than five billion years ago.”

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Sun Sheds Its Skin

DID YOU KNOW…

(6). “The sun loses material from its surface at a rate of one million tons per second.”

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Stars Outnumber Words Uttered By Humans?

DID YOU KNOW…

(5). “There are more stars in the universe than grains of sand on any beach, more stars than seconds have passed since Earth formed, more stars than words and sounds ever uttered by all the humans who ever lived.”

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Nobody owns the air they breathe, believe it or not

DID YOU KNOW THIS…

(4). “A single breath of air draws in more air molecules than there are single breathfuls of air in Earth’s entire atmosphere. That means some of the air you just breathed passed through the lungs of Napolean, Beethoven, Lincoln, and Billy the Kid.”

 

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How old is the water you drink?

DID YOU KNOW…

(3). “There are more molecules of water in a cup of the stuff than there are cups of water in all the world’s oceans. Every cup that passes through a single person and eventually rejoins the world’s water supply hold enough molecules to mix 1,500 of them into every cup of water in the world. No way around it: some of the water you just drank passed through the kidneys of Socrates, Genghis Khan and Joan of Arc.”

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Do huge genetic gaps among earths creatures exist?

DID YOU KNOW…

2. ASTROPHYSICS FACTS

(2). “If a huge genetic gap separated us from our closest relative in the animal kingdom, we could justifiably celebrate our brilliance. We might be entitled to walk around thinking we’re distant and distinct from our fellow creatures. But no such gap exists. Instead, we are one with the rest of nature, fitting neither above nor below, but within.”

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