A terrible human being
- Aug 18, 2014
[DOUBLEPOST=1520304622][/DOUBLEPOST]https://www.theguardian.com/science...tect-signals-from-first-stars-in-the-universeHow did life start? There may not be a bigger question. To learn the secret of our origins means going back beyond the earliest forms of biological life, past simple bacteria, and down to the chemistry of the building blocks that came earlier.
Most people have heard DNA’s double helix described as the blueprint for life, but its single-stranded relative RNA is also critical for transmitting genetic information. Both are present in the cells of all living organisms, and many scientists suspect that RNA was the original genetic material, coming on the scene before DNA, more than four billion years ago during a period scientists call “RNA world.”
But to build the RNA world, RNA and other biomolecules had to come together in the first place. Their constituent parts have a distinctive chemical property called chirality that’s related to how their atoms are arranged. And a debate has broken out about how life’s chirality got started: is it the product of the chemical environment of the early Earth, or did life inherit its chirality from space?
For some scientists, homing in on how a chain of genetic material was able to come together to start terrestrial life now involves looking away from Earth. One idea being explored in astrobiology is whether some prebiotic organic molecules could have been delivered to Earth by meteorites or dust grains. Recent discoveries in interstellar space may be providing some support for this.
In 2011, NASA published a study of meteorites suggesting that they contain nucleobases, chemicals that are components of both DNA and RNA. Thus, a critical starting material for life may have been seeded to early Earth from space. A year later, a team at the University of Copenhagen reported finding a sugar molecule in interstellar space that can be chemically transformed into ribose—the “R” in RNA. Last year, the same team uncovered a more complex molecule (methyl isocyanate) in a star-forming region more than 400 light years away from Earth.
And in 2016, two postdoctoral researchers, Brett McGuire (National Radio Astronomy Observatory, Virginia) and Brandon Carroll (California Institute of Technology), working with astronomers at the Parkes Observatory in Australia, reported the detection of a molecule in interstellar space, near the center of the Milky Way, that could have distinct consequences for the narrative of terrestrial life.
Where no chiral molecule has gone before
McGuire and Carroll discovered a molecule called propylene oxide (molecular formula: C3H6O) 25,000 light years away from Earth, in a star-forming region of our galaxy called Sagittarius B. But it wasn’t the chemical itself that was surprising; this propylene oxide bears a property that has been associated exclusively with life on Earth.
Propylene oxide is what is known as a “chiral” molecule (pronounced KY-ral, from the Greek word cheir for hand), which means that it comes in two forms: right- and left-handed. Chiral molecules have the same chemical formula, and their structures are nearly identical except for certain atoms that are attached on different sides of the three-dimensional molecule. In the case of propylene oxide, it’s the methyl group (CH3) that can attach to one of two carbons, as shown below.
The two forms of a chiral molecule cannot be superimposed on each other on a level plane, much like when you place one hand on top of the other and a thumb sticks out at either end—the hands are mirror images of each other. The French microbiologist Louis Pasteur discovered this quirk of nature more than 150 years ago.
What he didn’t realize was that he happened upon a fundamental feature of organic matter: as molecules get more complex, chirality is all but guaranteed. While it doesn’t change the number or types of atoms in that molecule, the differences in how those atoms attach can impact a molecule’s function. One example is limonene, a key component of the scent of citrus fruit. The right-handed version tastes like lemon, while the left-handed one like orange. Ditto for the molecule carvone: in caraway seeds, the left-handed version binds to a receptor in neurons that line the base of your nose that send a signal to your brain telling it that it has smelled rye bread; the right-sided carvone signals your brain that it has smelled spearmint.
Beyond smell and taste, chirality determines the shape of our large-scale biological structures. The famous double helix of a DNA strand twists right, along with the sugars that comprise its backbone; the amino acids in proteins twist left. Despite the fact that these molecules naturally occur in both orientations, all the living organisms on Earth appear to have DNA that is built on the blueprint of it twisting right—perhaps descended from a single right-handed twist in the ancient RNA world.
The enzymes that help our body use amino acids and DNA bases work because they recognize the specific shapes of these molecules. An amino acid with a different chirality would have a different shape, keeping those enzymes from interacting properly with it. If you were served a burger of protein that had right-handed amino acids, your body would not be able to break it down.
This deep bias that permeates all life must have had a beginning. And McGuire and Carroll suggest that their discovery of chiral propylene oxide—as well as the earlier discoveries of methyl isocyanate and glycoaldehyde—shows that space may have had a “hand” in life’s origins.
“This is the first chiral molecule detected in outer space,” said McGuire, who is the Jansky Postdoctoral Fellow with the National Radio Astronomy Observatory. Its detection suggests that a bias toward one form of chirality is not limited to life on Earth, as has been previously thought, and lends evidence to the idea that material from elsewhere in the Solar System—possibly including some much older than Earth or even our Solar System—may have seeded the earliest chemicals necessary to form life on our planet.
Of course, chirality isn’t the only problem you have to solve—the chiral molecules we’ve seen in space are much less complex than most biomolecules.
The molecular puzzle
Ever since the Watson and Crick discovery of the structure of DNA, scientists have wanted to understand how simple atoms combined to form the double helix. Myriad experiments from the 1950s on (with the Miller-Urey being the most famous among them) showed that heating gases that were likely present on early Earth, such as methane, ammonia, and hydrogen, creates a “primordial soup” that includes amino acids, the building blocks of proteins. Followup and related experiments showed that nucleotides (which form the base pairs of DNA and RNA) could also form in similar conditions.
Combined with the later discovery that RNA could catalyze chemical reactions, this paved the way for a chemical theory about the origin of life: the RNA world. Basic chemistry could allow RNA precursors to form and possibly combine to make RNA. Once RNA formed, the biomolecule could catalyze a self-copying reaction to make more of itself. Over time, even more sophisticated chemistry could arise from the pool of self-copying RNA molecules.
It sounded logical, but it hit some roadblocks when scientists began to consider how the pieces fit together. It turned out you couldn’t solve the chemistry without solving chirality, too.
Gerald Joyce, who is currently professor at Salk Institute for Biological Sciences, was a young biochemist in the 1980s when he began to investigate for his doctoral research how nucleobases can come together to form complex biomolecules. In a Nature paper from 1984, he described how he tried to get simple chemical molecules to coalesce into larger biological complexes. Replicating the 1950s experiment, he found that the right catalysts allowed his primordial soup (carbon-, nitrogen-, oxygen-, and hydrogen-containing molecules) to generate the RNA bases adenine, guanine, cytosine, and uracil.
These are all chiral molecules, and both the right- and left-handed versions were present in equal proportion in the “soup.” When they came together to form an RNA molecule, there was no mechanism to establish any consistency in how they attached—right could follow left, left right, and so on. This random assortment meant that nucleotides of different chirality were present on the molecule’s sugar backbone; Joyce found that the addition of further nucleotides was very inefficient. Other scientists who built mathematical models showed that adding a nucleotide of the wrong-handedness stops the chain from extending, confirmed Joyce’s research.
So starting with both right- and left-handed versions (known as enantiomers) of nucleotides didn’t allow complex RNA molecules to form. “Without homochirality we would not have complex biological structures,“ said Donna Blackmond, a biochemist at Scripps Institute. (Blackmond was not involved in the CalTech discovery or in Joyce’s research.)
Blackmond thinks that both versions of chiral molecules were present on ancient Earth, but at some point a bias toward one form had to creep in, creating what’s referred to as enantiomeric excess. “Symmetry had to be broken, and we had to have some significant enantiomeric excess before prebiotic reactions could start,” she told Ars. She suspects that excess of one enantiomer over another could, over time, weed out the unneeded enantiomer and establish “homochirality” (only one kind of enantiomer) for certain key molecules.
Even if you have a tiny majority of one enantiomer, lab experiments have shown that it can lead to a much higher excess. The first experiment to show this dates to the late 1950s. Kenso Soia in Japan found that enantiomers can favor their own production. If both the right- and left-hand versions are copied independently, then the amount of both kinds would grow. Soia showed that the enantiomers tend to pair up in both same type and different type units, and the two aren’t copied at equal rates. When a right-handed form pairs up with a left-handed one, they become inactive and stop replicating.
Through this process, a small excess of one enantiomer can grow into a much larger surplus. More recent mathematical models have supported Soia's idea. Over time, the amplification process can result in the dominance of one chirality and eventually perhaps lead to the minority one disappearing. When biomolecules form from the resulting mix, they would condense with an overwhelming majority of their parts having a single chirality. Self replication could then establish a population with just a single chirality, which makes the building of an RNA strand more efficient.
Laurence Barron, a chemist at the University of Glasgow, (he occupies the chair once held by Lord Kelvin of absolute zero fame) says that if you start out with uneven amounts of different chiral forms, it is necessary to have some sort of amplification process to allow a small majority of one enantiomer to grow into a much wider margin. This has been shown to work in laboratory through autocatalysis.
But there’s disagreement about the details of how an excess of one enantiomer grew and where it might have happened.
McGuire and Carroll say most scientists have assumed that “homochirality doesn’t occur in space, and is a hallmark of life, and [is] therefore something that must have its origins on Earth.” But they speculate about a possible alternative: “chirality in space could have kickstarted a homochiral process on Earth.”
They suggest that space could have provided the initial impetus through light. As light travels, its oscillating electric and magnetic fields can trace a corkscrew, called circular polarization. Polarized light interacts with different enantiomers differently. Barron explained that circularly polarized ultraviolet light (known as UV–CPL) will decompose enantiomers that rotate the same way the light does, at least in the lab. This results in an abundance of molecules with the opposite chirality. So if a cloud of gas in space that contained both right- and left-handed molecules met a ray of polarized light, the mixture could have ended up having a majority of one enantiomer.
The timing on that is flexible. Barron notes that, while some might think that enantiomeric enrichment would occur as the young Earth cooled, the process could also have been happening for billions of years before the planet was formed, with chiral chemicals later delivered to the early Earth by comets.
Some evidence for this comes from a meteorite that was found in Murchison, Australia in 1969. We don’t know the precise origins of meteorites, which are thought to have formed very early in the Solar System’s history. Having them come back to Earth is like a time capsule that can give us a peek into the chemistry that existed then. If meteors have enantiomeric excesses, it would support the idea that homochirality arrived on Earth via molecules from space.
Samples from the Murchison meteorite show that amino acids had a 10 percent surplus of the left-handed enantiomers. While not a strong excess, it’s clear that space can have an enrichment of one type of chirality.
“This turns out to be a small effect, but over time it can add up,” McGuire said.
And University of Glasgow’s Barron added that “UV-CPL is not common in the cosmos, but it has been detected, inter alia, in star-formation regions.”
Stefanie Milam, an astrochemist at NASA, said the discovery of chiral propylene oxide in space was exciting because it supports the possibility that the “bias happened independent of biological processes.” Space could have given Earth a head start. “If a meteorite seeds a planet with water and chiral molecules, then you’re starting with sophisticated chemistry,” she said.
An expert on the star-forming region where propylene oxide was found, called Sagittarius B2, Milam says it’s 25,000 light years away from Earth and located in the middle of our galaxy. It’s a region where stars are still forming, very much what our Solar System’s neighborhood may have looked like 4.6 billion years ago. Looking at Sagittarius B2 is “like looking back in time, at what early Earth would have looked like, too,” Carroll added.
“Looking” might be a bit optimistic, though. Scientists cannot actually “see” molecules like propylene oxide or other molecules found there, like glycoaldehyde or methyl isocyanate (reported by the Copenhagen team). ALMA (Atacama Large Millimeter/submillimeter Array) in Chile (used by the Copenhagen team) and the Green Bank Telescope in West Virginia, where McGuire is a postdoctoral fellow, are highly sensitive radio telescopes. They do not obtain colorful images of distant galaxies like the Hubble; these telescopes pick up photons at frequencies emitted or absorbed by molecules, telling us what’s there. But there are limits to what we can learn; the larger the molecule, the fainter the signal, and their detection via radio astronomy becomes more difficult.
“Propylene oxide is one of the simplest chiral molecules we can find,” McGuire explained. “It is possible that there are many more chiral molecules in space, but it’ll have to await our ability to resolve their presence.” The Green Bank data also wasn’t able to tell McGuire and Carroll whether the propylene oxide was a right- or left-handed enantiomer.
That level of detail may have to wait until actual molecules are retrieved from space and analyzed. The most promising possibilities come from planned NASA space probes that will attach themselves to bodies such as comets. Comets are chunks of planetary bodies that formed at the birth of the Solar System and, consequently, contain the chemistry as it existed then—Milam calls them “pristine relics of when the Sun actually formed" that "have volatile material on them.” It’s also possible that comets from exosolar systems got pulled into our Sun’s gravitational field. They can carry information about chemistry that is happening in another solar system.
An examination of molecules in outer space was part of the recent Rosetta mission. Rosetta followed comet 67P (GG), which is thought to be 4.6 billion years old—the same age as our Solar System. Rosetta sent back mass spectrometry data showing that glycine, the simplest amino acid, was present on the comet. Although glycine is not chiral, it’s possible that other probes will find more complex molecules. Osiris Rex is due to retrieve sample material from asteroid Bennu in 2018, the first time that we are due to receive actual material from an asteroid without having it land on earth first and risk contamination.
Jason Dworkin of NASA, who studies meteors (which are meteorites that have not yet reached Earth’s atmosphere and therefore are not contaminated with earthly matter), said that over the past decade technology has improved so much, we can have confidence that any chiral molecules we find there are truly from space.
“Having access to sample material from an asteroid would allow us to see the kind of complex chemistry that was available on early Earth,” Dworkin said.
And it would also help scientists pinpoint other places that life may still start. Our galaxy, the Milky Way, is filled with many exosolar systems, each with planets orbiting a star. Some might enjoy the same Goldilocks conditions that made life on Earth possible, like liquid water and moderate radiation. Other regions in our galaxy are actively forming new stars and can provide models for the early Solar System. These include IRAS 16293-2422, a star 400 light years away from Earth where the glycoaldehyde and methyl isocyanate were detected, and Sagittarius B2, a star-forming region 25,000 light years away that we mentioned above. In addition to being where the propylene oxide molecule was detected, it contains billions of liters of alcohol.
While our imaging capabilities aren’t yet at the point where we can tell for certain, it’s possible that some newly forming systems recreate the environment of early Earth—a place where life is able to originate. (Some have termed these “originable zones.”) Studying the molecules present in these zones can help us understand what happened on Earth.
McGuire and Carroll are hopeful that the next few years will give us access to more chemistry from outer space, such as amino acids that can give more certain information about the provenance of life. Hopefully, this will only shed more light on how homochirality developed—or even change our notion of its terrestrial origins.
Astronomers have detected a signal from the first stars as they appeared and illuminated the universe, in observations that have been hailed as “revolutionary”.
The faint radio signals suggest the universe was lifted out of total darkness 180m years after the big bang in a momentous transition known as the cosmic dawn.
The faint imprint left by the glow of the earliest stars also appears to contain new and unexpected evidence about the existence and nature of dark matter which, if confirmed by independent observatories, would mark a second major breakthrough.
“Finding this minuscule signal has opened a new window on the early universe,” said Judd Bowman of Arizona State University, whose team set out to make the detection more than a decade ago. “It’s unlikely we’ll be able to see any earlier into the history of stars in our lifetime.”
Following the big bang, the universe initially existed as a cold, starless expanse of hydrogen gas awash with radiation, known as the Cosmic Microwave Background. This radiation still permeates all of space today and astronomers are beginning to scrutinise this cosmic backdrop for traces of events that occurred in the deep past.
During the next 100m years – a period known as the dark ages – gravity pulled slightly denser regions of gas into clumps and eventually some collapsed inwards to form the first stars, which were massive, blue and short-lived. As these stars lit up the surrounding gas, the hydrogen atoms were excited, causing them to start absorbing radiation from the Cosmic Microwave Background at a characteristic wavelength.
This led scientists to predict that the cosmic dawn must have left an imprint in the Cosmic Microwave Background radiation in the form of a dip in brightness at a specific point in the spectrum that ought, in theory, to still be perceptible today.
In practice, detecting this signal has proved hugely challenging, however, and has eluded astronomers for more than a decade. The dip is swamped by other, more local, sources of radio waves. And the expansion of the universe means the signal is “red-shifted” away from its original characteristic wavelength by an amount that depends on precisely when the first stars switched on. So scientists were also not sure exactly where in the spectrum they should be looking –and some predicted the task would prove impossible.
“The team have to pick up radio waves and then search for a signal that’s around 0.01% of the contaminating radio noise coming from our own galaxy,” said Andrew Pontzen, a cosmologist at University College London. “It’s needle-in-a-haystack territory.”
Remarkably, Bowman and colleagues appear to have overcome these odds using a small, crude-looking instrument the size of a small table. The Edges (Experiment to Detect Global EoR Signature) antenna sits in a remote region of Western Australia where there are few human sources of radio waves to interfere with incoming signals from the distant universe. The wavelength of the dip suggest that the cosmic dawn occurred about 180m years after the big bang, 13.6bn years ago and nine billion years before the birth of the sun.
The signal also indicated a second milestone at 250m years after the big bang, when the early stars died and black holes, supernovae and other objects they left behind heated up the the remaining free hydrogen with x-rays.
In a paper published in the journal Nature, Bowman and colleagues detail the elaborate experimental steps they took to prove the signal was real – several years of replications, changing the angle of the antenna, altering the setup.
“Telescopes cannot see far enough to directly image such ancient stars, but we’ve seen when they turned on in radio waves arriving from space,” said Bowman.
Emma Chapman, Royal Astronomical Society research fellow at Imperial College London, described the result as “an incredible achievement, constituting the first ever detection of the era of the first stars”. The huge significance of the result, she added, meant it needed to be replicated by an independent experiment.
The detection also contained a major surprise. The size of the dip was twice as big as predicted. This suggests the primordial hydrogen gas was absorbing more background radiation than predicted and would suggest the universe was significantly colder than previously thought, at about -270C.
In a second [URL='http://nature.com/articles/doi:10.1038/nature25791']Nature paper, Rennan Barkana, a professor of astrophysics at Tel Aviv University, proposes a potentially groundbreaking explanation: that the hydrogen gas was losing heat to dark matter. Until now, the existence of dark matter – the elusive substance that is thought to make up 85% of the matter in the universe – has only been inferred indirectly from its gravitational effects. If confirmed, these results would suggest a new form of interaction between normal matter and dark matter, mediated by a fundamental force that until now has been entirely unknown.
The theory would also suggest that dark matter particles, the properties of which remain completely mysterious, must be light rather than heavy, which would rule out one of the leading hypothetical candidates for dark matter, known as weakly interacting massive particles – or wimps.
Lincoln Greenhill, a senior astronomer at Harvard University, said that if confirmed the dark matter observations could be revolutionary. “We know so little about it that there are many theories as to what dark matter is,” he said. “Many may shortly be eliminated from the running.”
This article was amended on 28 February to clarify the way new evidence on the temperature of the universe was expressed.[/URL]
The dream of nuclear fusion is on the brink of being realised, according to a major new US initiative that says it will put fusion power on the grid within 15 years.
The project, a collaboration between scientists at MIT and a private company, will take a radically different approach to other efforts to transform fusion from an expensive science experiment into a viable commercial energy source. The team intend to use a new class of high-temperature superconductors they predict will allow them to create the world’s first fusion reactor that produces more energy than needs to be put in to get the fusion reaction going.
Bob Mumgaard, CEO of the private company Commonwealth Fusion Systems, which has attracted $50 million in support of this effort from the Italian energy company Eni, said: “The aspiration is to have a working power plant in time to combat climate change. We think we have the science, speed and scale to put carbon-free fusion power on the grid in 15 years.”
The promise of fusion is huge: it represents a zero-carbon, combustion-free source of energy. The problem is that until now every fusion experiment has operated on an energy deficit, making it useless as a form of electricity generation. Decades of disappointment in the field has led to the joke that fusion is the energy of the future – and always will be.
The just-over-the-horizon timeframe normally cited is 30 years, but the MIT team believe they can halve this by using new superconducting materials to produce ultra-powerful magnets, one of the main components of a fusion reactor.
Prof Howard Wilson, a plasma physicist at York University who works on different fusion projects, said: “The exciting part of this is the high-field magnets.”
Fusion works on the basic concept of forging lighter elements together to form heavier ones. When hydrogen atoms are squeezed hard enough, they fuse together to make helium, liberating vast amounts of energy in the process.
However, this process produces net energy only at extreme temperatures of hundreds of millions of degrees celsius – hotter than the centre of the sun and far too hot for any solid material to withstand.
To get around this, scientists use powerful magnetic fields to hold in place the hot plasma – a gaseous soup of subatomic particles – to stop it from coming into contact with any part of the doughnut-shaped chamber.
A newly available superconducting material – a steel tape coated with a compound called yttrium-barium-copper oxide, or YBCO – has allowed scientists to produce smaller, more powerful magnets. And this potentially reduces the amount of energy that needs to be put in to get the fusion reaction off the ground.
“The higher the magnetic field, the more compactly you can squeeze that fuel,” said Wilson.
The planned fusion experiment, called Sparc, is set to be far smaller – about 1/65th of the volume – than that of the International Thermonuclear Experimental Reactor project, an international collaboration currently being constructed in France.
The experimental reactor is designed to produce about 100MW of heat. While it will not turn that heat into electricity, it will produce, in pulses of about 10 seconds, as much power as is used by a small city. The scientists anticipate the output would be more than twice the power used to heat the plasma, achieving the ultimate technical milestone: positive net energy from fusion.
Prof Wilson was also cautious about the timeframe, saying that while the project was exciting he couldn’t see how it would achieve its goal of putting energy on the grid within 15 years.
Unlike with fossil fuels, or nuclear fuel like uranium used in fission reactions, there will never be a shortage of hydrogen.
The reaction also does not create greenhouse gases or produce hazardous radioactive waste of the sort made by conventional nuclear fission reactors.
Prof Maria Zuber, MIT’s vice-president for research, said that the development could represent a major advance in tackling climate change. “At the heart of today’s news is a big idea - a credible, viable plan to achieve net positive energy for fusion,” she said.
“If we succeed, the world’s energy systems will be transformed. We’re extremely excited about this.”
In 1935, when both quantum mechanics and Albert Einstein’s general theory of relativity were young, a little-known Soviet physicist named Matvei Bronstein, just 28 himself, made the first detailed study of the problem of reconciling the two in a quantum theory of gravity. This “possible theory of the world as a whole,” as Bronstein called it, would supplant Einstein’s classical description of gravity, which casts it as curves in the space-time continuum, and rewrite it in the same quantum language as the rest of physics.
Bronstein figured out how to describe gravity in terms of quantized particles, now called gravitons, but only when the force of gravity is weak — that is (in general relativity), when the space-time fabric is so weakly curved that it can be approximated as flat. When gravity is strong, “the situation is quite different,” he wrote. “Without a deep revision of classical notions, it seems hardly possible to extend the quantum theory of gravity also to this domain.”
His words were prophetic. Eighty-three years later, physicists are still trying to understand how space-time curvature emerges on macroscopic scales from a more fundamental, presumably quantum picture of gravity; it’s arguably the deepest question in physics. Perhaps, given the chance, the whip-smart Bronstein might have helped to speed things along. Aside from quantum gravity, he contributed to astrophysics and cosmology, semiconductor theory, and quantum electrodynamics, and he also wrote several science books for children, before being caught up in Stalin’s Great Purge and executed in 1938, at the age of 31.
The search for the full theory of quantum gravity has been stymied by the fact that gravity’s quantum properties never seem to manifest in actual experience. Physicists never get to see how Einstein’s description of the smooth space-time continuum, or Bronstein’s quantum approximation of it when it’s weakly curved, goes wrong.
The problem is gravity’s extreme weakness. Whereas the quantized particles that convey the strong, weak and electromagnetic forces are so powerful that they tightly bind matter into atoms, and can be studied in tabletop experiments, gravitons are individually so weak that laboratories have no hope of detecting them. To detect a graviton with high probability, a particle detector would have to be so huge and massive that it would collapse into a black hole. This weakness is why it takes an astronomical accumulation of mass to gravitationally influence other massive bodies, and why we only see gravity writ large.
Not only that, but the universe appears to be governed by a kind of cosmic censorship: Regions of extreme gravity — where space-time curves so sharply that Einstein’s equations malfunction and the true, quantum nature of gravity and space-time must be revealed — always hide behind the horizons of black holes.
“Even a few years ago it was a generic consensus that, most likely, it’s not even conceivably possible to measure quantization of the gravitational field in any way,” said Igor Pikovski, a theoretical physicist at Harvard University.
Now, a pair of papers recently published in Physical Review Letters has changed the calculus. The papers contend that it’s possible to access quantum gravity after all — while learning nothing about it. The papers, written by Sougato Bose at University College London and nine collaborators and by Chiara Marletto and Vlatko Vedral at the University of Oxford, propose a technically challenging, but feasible, tabletop experiment that could confirm that gravity is a quantum force like all the rest, without ever detecting a graviton. Miles Blencowe, a quantum physicist at Dartmouth College who was not involved in the work, said the experiment would detect a sure sign of otherwise invisible quantum gravity — the “grin of the Cheshire cat.”
A levitating microdiamond (green dot) in Gavin Morley’s lab at the University of Warwick, in front of the lens used to trap the diamond with light.
Gavin W Morley
The proposed experiment will determine whether two objects — Bose’s group plans to use a pair of microdiamonds — can become quantum-mechanically entangled with each other through their mutual gravitational attraction. Entanglement is a quantum phenomenon in which particles become inseparably entwined, sharing a single physical description that specifies their possible combined states. (The coexistence of different possible states, called a “superposition,” is the hallmark of quantum systems.) For example, an entangled pair of particles might exist in a superposition in which there’s a 50 percent chance that the “spin” of particle A points upward and B’s points downward, and a 50 percent chance of the reverse. There’s no telling in advance which outcome you’ll get when you measure the particles’ spin directions, but you can be sure they’ll point opposite ways.
The authors argue that the two objects in their proposed experiment can become entangled with each other in this way only if the force that acts between them — in this case, gravity — is a quantum interaction, mediated by gravitons that can maintain quantum superpositions. “If you can do the experiment and you get entanglement, then according to those papers, you have to conclude that gravity is quantized,” Blencowe explained.
To Entangle a Diamond
Quantum gravity is so imperceptible that some researchers have questioned whether it even exists. The venerable mathematical physicist Freeman Dyson, 94, has argued since 2001 that the universe might sustain a kind of “dualistic” description, where “the gravitational field described by Einstein’s theory of general relativity is a purely classical field without any quantum behavior,” as he wrote that year in The New York Review of Books, even though all the matter within this smooth space-time continuum is quantized into particles that obey probabilistic rules.
Dyson, who helped develop quantum electrodynamics (the theory of interactions beween matter and light) and is professor emeritus at the Institute for Advanced Study in Princeton, New Jersey, where he overlapped with Einstein, disagrees with the argument that quantum gravity is needed to describe the unreachable interiors of black holes. And he wonders whether detecting the hypothetical graviton might be impossible, even in principle. In that case, he argues, quantum gravity is metaphysical, rather than physics.
What’s beautiful about the arguments is that you don’t really need to know what the quantum theory [of gravity] is, specifically.
He is not the only skeptic. The renowned British physicist Sir Roger Penrose and, independently, the Hungarian researcher Lajos Diósi have hypothesized that space-time cannot maintain superpositions. They argue that its smooth, solid, fundamentally classical nature prevents it from curving in two different possible ways at once — and that its rigidity is exactly what causes superpositions of quantum systems like electrons and photons to collapse. This “gravitational decoherence,” in their view, gives rise to the single, rock-solid, classical reality experienced at macroscopic scales.
The ability to detect the “grin” of quantum gravity would seem to refute Dyson’s argument. It would also kill the gravitational decoherence theory, by showing that gravity and space-time do maintain quantum superpositions.
Bose’s and Marletto’s proposals appeared simultaneously mostly by chance, though experts said they reflect the zeitgeist. Experimental quantum physics labs around the world are putting ever-larger microscopic objects into quantum superpositions and streamlining protocols for testing whether two quantum systems are entangled. The proposed experiment will have to combine these procedures while requiring further improvements in scale and sensitivity; it could take a decade or more to pull it off. “But there are no physical roadblocks,” said Pikovski, who also studies how laboratory experiments might probe gravitational phenomena. “I think it’s challenging, but I don’t think it’s impossible.”
The plan is laid out in greater detail in the paper by Bose and co-authors — an Ocean’s Eleven cast of experts for different steps of the proposal. In his lab at the University of Warwick, for instance, co-author Gavin Morley is working on step one, attempting to put a microdiamond in a quantum superposition of two locations. To do this, he’ll embed a nitrogen atom in the microdiamond, next to a vacancy in the diamond’s structure, and zap it with a microwave pulse. An electron orbiting the nitrogen-vacancy system both absorbs the light and doesn’t, and the system enters a quantum superposition of two spin directions — up and down — like a spinning top that has some probability of spinning clockwise and some chance of spinning counterclockwise. The microdiamond, laden with this superposed spin, is subjected to a magnetic field, which makes up-spins move left while down-spins go right. The diamond itself therefore splits into a superposition of two trajectories.
In the full experiment, the researchers must do all this to two diamonds — a blue one and a red one, say — suspended next to each other inside an ultracold vacuum. When the trap holding them is switched off, the two microdiamonds, each in a superposition of two locations, fall vertically through the vacuum. As they fall, the diamonds feel each other’s gravity. But how strong is their gravitational attraction?
If gravity is a quantum interaction, then the answer is: It depends. Each component of the blue diamond’s superposition will experience a stronger or weaker gravitational attraction to the red diamond, depending on whether the latter is in the branch of its superposition that’s closer or farther away. And the gravity felt by each component of the red diamond’s superposition similarly depends on where the blue diamond is.
In each case, the different degrees of gravitational attraction affect the evolving components of the diamonds’ superpositions. The two diamonds become interdependent, meaning that their states can only be specified in combination — if this, then that — so that, in the end, the spin directions of their two nitrogen-vacancy systems will be correlated.
Lucy Reading-Ikkanda/Quanta Magazine
After the microdiamonds have fallen side by side for about three seconds — enough time to become entangled by each other’s gravity — they then pass through another magnetic field that brings the branches of each superposition back together. The last step of the experiment is an “entanglement witness” protocol developed by the Dutch physicist Barbara Terhal and others: The blue and red diamonds enter separate devices that measure the spin directions of their nitrogen-vacancy systems. (Measurement causes superpositions to collapse into definite states.) The two outcomes are then compared. By running the whole experiment over and over and comparing many pairs of spin measurements, the researchers can determine whether the spins of the two quantum systems are correlated with each other more often than a known upper bound for objects that aren’t quantum-mechanically entangled. In that case, it would follow that gravity does entangle the diamonds and can sustain superpositions.
“What’s beautiful about the arguments is that you don’t really need to know what the quantum theory is, specifically,” Blencowe said. “All you have to say is there has to be some quantum aspect to this field that mediates the force between the two particles.”
Technical challenges abound. The largest object that’s been put in a superposition of two locations before is an 800-atom molecule. Each microdiamond contains more than 100 billion carbon atoms — enough to muster a sufficient gravitational force. Unearthing its quantum-mechanical character will require colder temperatures, a higher vacuum and finer control. “So much of the work is getting this initial superposition up and running,” said Peter Barker, a member of the experimental team based at UCL who is improving methods for laser-cooling and trapping the microdiamonds. If it can be done with one diamond, Bose added, “then two doesn’t make much of a difference.”
Why Gravity Is Unique
Quantum gravity researchers do not doubt that gravity is a quantum interaction, capable of inducing entanglement. Certainly, gravity is special in some ways, and there’s much to figure out about the origin of space and time, but quantum mechanics must be involved, they say. “It doesn’t really make much sense to try to have a theory in which the rest of physics is quantum and gravity is classical,” said Daniel Harlow, a quantum gravity researcher at the Massachusetts Institute of Technology. The theoretical arguments against mixed quantum-classical models are strong (though not conclusive).
On the other hand, theorists have been wrong before, Harlow noted: “So if you can check, why not? If that will shut up these people” — meaning people who question gravity’s quantumness — “that’s great.”
Dyson wrote in an email, after reading the PRL papers, “The proposed experiment is certainly of great interest and worth performing with real quantum systems.” However, he said the authors’ way of thinking about quantum fields differs from his. “It is not clear to me whether [the experiment] would settle the question whether quantum gravity exists,” he wrote. “The question that I have been asking, whether a single graviton is observable, is a different question and may turn out to have a different answer.”
In fact, the way Bose, Marletto and their co-authors think about quantized gravity derives from how Bronstein first conceived of it in 1935. (Dyson called Bronstein’s paper “a beautiful piece of work” that he had not seen before.) In particular, Bronstein showed that the weak gravity produced by a small mass can be approximated by Newton’s law of gravity. (This is the force that acts between the microdiamond superpositions.) According to Blencowe, weak quantized-gravity calculations haven’t been developed much, despite being arguably more physically relevant than the physics of black holes or the Big Bang. He hopes the new experimental proposal will spur theorists to find out whether there are any subtle corrections to the Newtonian approximation that future tabletop experiments might be able to probe.
Leonard Susskind, a prominent quantum gravity and string theorist at Stanford University, saw value in carrying out the proposed experiment because “it provides an observation of gravity in a new range of masses and distances.” But he and other researchers emphasized that microdiamonds cannot reveal anything about the full theory of quantum gravity or space-time. He and his colleagues want to understand what happens at the center of a black hole, and at the moment of the Big Bang.
Perhaps one clue as to why it is so much harder to quantize gravity than everything else is that other force fields in nature exhibit a feature called “locality”: The quantum particles in one region of the field (photons in the electromagnetic field, for instance) are “independent of the physical entities in some other region of space,” said Mark Van Raamsdonk, a quantum gravity theorist at the University of British Columbia. But “there’s at least a bunch of theoretical evidence that that’s not how gravity works.”
In the best toy models of quantum gravity (which have space-time geometries that are simpler than those of the real universe), it isn’t possible to assume that the bendy space-time fabric subdivides into independent 3-D pieces, Van Raamsdonk said. Instead, modern theory suggests that the underlying, fundamental constituents of space “are organized more in a 2-D way.” The space-time fabric might be like a hologram, or a video game: “Even though the picture is three-dimensional, the information is stored in some two-dimensional computer chip,” he said. In that case, the 3-D world is illusory in the sense that different parts of it aren’t all that independent. In the video-game analogy, a handful of bits stored in the 2-D chip might encode global features of the game’s universe.
The distinction matters when you try to construct a quantum theory of gravity. The usual approach to quantizing something is to identify its independent parts — particles, say — and then apply quantum mechanics to them. But if you don’t identify the correct constituents, you get the wrong equations. Directly quantizing 3-D space, as Bronstein did, works to some extent for weak gravity, but the method fails when space-time is highly curved.
Witnessing the “grin” of quantum gravity would help motivate these abstract lines of reasoning, some experts said. After all, even the most sensible theoretical arguments for the existence of quantum gravity lack the gravitas of experimental facts. When Van Raamsdonk explains his research in a colloquium or conversation, he said, he usually has to start by saying that gravity needs to be reconciled with quantum mechanics because the classical space-time description fails for black holes and the Big Bang, and in thought experiments about particles colliding at unreachably high energies. “But if you could just do this simple experiment and get the result that shows you that the gravitational field was actually in a superposition,” he said, then the reason the classical description falls short would be self-evident: “Because there’s this experiment that suggests gravity is quantum.”
Correction March 6, 2018: An earlier version of this article referred to Dartmouth University. Despite the fact that Dartmouth has multiple individual schools, including an undergraduate college as well as academic and professional graduate schools, the institution refers to itself as Dartmouth College for historical reasons.
Amy Tietel is so fucking hot!one critique of the Herpes video, she should have been in a bikini.
It is a bit of a stretch, but by no means impossible or even unlikely that a hybrid or a chimera combining a human being and a chimpanzee could be produced in a laboratory. After all, human and chimp (or bonobo) share, by most estimates, roughly 99 percent of their nuclear DNA. Granted this 1 percent difference presumably involves some key alleles, the new gene-editing tool CRISPR offers the prospect (for some, the nightmare) of adding and deleting targeted genes as desired. As a result, it is not unreasonable to foresee the possibility—eventually, perhaps, the likelihood—of producing “humanzees” or “chimphumans.” Such an individual would not be an exact equal-parts-of-each combination, but would be neither human nor chimp: rather, something in between.
If that prospect isn’t shocking enough, here is an even more controversial suggestion: Doing so would be a terrific idea.
The year 2018 is the bicentennial of Mary Shelley’s Frankenstein, subtitled the modern Prometheus. Haven’t we learned that Promethean hubris leads only to disaster, as did the efforts of the fictional Dr. Frankenstein? But there are also other disasters, currently ongoing, such as the grotesque abuse of nonhuman animals, facilitated by what might well be the most hurtful theologically-driven myth of all times: that human beings are discontinuous from the rest of the natural world, since we were specially created and endowed with souls, whereas “they”—all other creatures—were not.
Of course, all that we know of evolution (and by now, it’s a lot) demands otherwise, since evolution’s most fundamental take-home message is continuity. And it is in fact because of continuity—especially those shared genes—that humanzees or chimphumans could likely be produced. Moreover, I propose that the fundamental take-home message of such creation would be to drive a stake into the heart of that destructive disinformation campaign of discontinuity, of human hegemony over all other living things. There is an immense pile of evidence already demonstrating continuity, including but not limited to physiology, genetics, anatomy, embryology, and paleontology, but it is almost impossible to imagine how the most die-hard advocate of humans having a discontinuously unique biological status could continue to maintain this position if confronted with a real, functioning, human-chimp combination.1
It is also possible, however, that my suggestion is doubly fanciful, not only with respect to its biological feasibility, but also whether such a “creation” would have the impact that I propose—and hope. Thus, chimpanzees are widely known to be very similar to human beings: They make and use tools, engage in complex social behavior (including elaborate communication and long-lasting mother-offspring bonds), they laugh, grieve, and affirmatively reconcile after conflicts. They even look like us. Although such recognition has contributed to outrage about abusing chimps—as well as other primates in particular—in circus acts, laboratory experiments, and so forth, it has not generated notable resistance to hunting, imprisoning and eating other animal species, which, along with chimps themselves, are still considered by most people to be “other” and not aspects of “ourselves.” (Chimps, moreover, are enthusiastically consumed in parts of equatorial Africa, where they are a prized component of “bush meat.”)
It is at least arguable that the ultimate benefit of teaching human beings their true nature would be worth the sacrifice paid by a few unfortunates.
In his book, Less Than Human: Why We Demean, Enslave, and Exterminate Others, David Livingstone Smith examined how dehumanization goes hand-in-hand with racism and genocide. Smith revealed a long-standing pattern whereby people, despite acknowledging that other human beings appear to be human, often maintain that in their essence—whatever that means—these others continue to be less than human. It is thus entirely possible that comparably stubborn biases will persist even if our biological continuity with other living things becomes undeniable. Moreover, people are certainly known to obscure inconvenient truths: It is said that when the wife of the Bishop of Worcester heard of Darwin’s scandalous theory, she exclaimed “Descended from apes? My dear, let us hope that it isn’t true, but if it is true, let us hope that it does not become widely known!”
On the other hand, it seems equally likely that faced with individuals who are clearly intermediate between human and ape, it will become painfully obvious that a rigid distinction between the two is no longer tenable. But what about those presumably unfortunate individuals thereby produced? Neither fish nor fowl, wouldn’t they find themselves intolerably unspecified and inchoate, doomed to a living hell of biological and social indeterminacy? This is possible, but it is at least arguable that the ultimate benefit of teaching human beings their true nature would be worth the sacrifice paid by a few unfortunates. It is also arguable, moreover, that such individuals might not be so unfortunate at all. For every chimphuman or humanzee frustrated by her inability to write a poem or program a computer, there could equally be one delighted by her ability to do so while swinging from a tree branch. And—more important—for any human being currently insistent upon his or her species’ specialness, to the ultimate detriment of literally millions of other individuals of millions of other species, such a development could well be a real mind expander and paradigm buster.
In the early days of biology, when special creation ruled, it was widely thought that species were rigid and fixed, each specially created as such. Now we know better. As currently recognized, a species is a group of naturally interbreeding individuals; that is, a population within which genes are regularly exchanged. Moreover, even though people like to think in terms of yes/no, either/or dichotomies, we also know that the boundaries between species are shifting and flexible: e.g., perfectly “good” species such as mallards and pintail ducks often interbreed, producing hybrids that can be the bane of even experienced birders. Grizzlies and polar bears also hybridize on occasion, producing “grolar” bears.
A recent study of the genomes of ravens—which occupy much of the Northern Hemisphere—found that this species had earlier divided into two, with a smaller population limited to California. Then these two raven species recombined several hundred thousand years ago, forming the single Holarctic raven species that we know today.1 Such “speciation reversal” may well be a more widespread phenomenon than previously thought. Elephants and mastodons evidently interbred before the latter went extinct.2 Wolves, coyotes, and domestic dogs have been hybridizing in recent decades, and it is clear that some populations of modern Homo sapiens contain as much as 5 percent Neanderthal genes, and some or all of us may also harbor an unknown soupcon from those mysterious hominins known as Denisovans. Princeton evolutionary biologist Rosemary Grant—who, along with her husband Peter, has long studied speciation among Galapagos finches—suggests that many animal species (including ourselves) are likely “haunted by the ghosts of interbreeding past.”
The possibility thus cannot be excluded that combining human and chimp may herald, or threaten, something biologically new on our—and their—horizon.
A hybrid is a cross between individuals of distinct genetic ancestry, which means that technically, nearly everyone is a hybrid, except for clones, identical twins, or perhaps persons produced by close incest. More usefully, we speak of hybridization as the process by which members of different sub-species are crossed (mating Labradors and poodles, for example, to produce labradoodles), or—more rarely—different species, in which case the resulting hybrids are often nonviable, either sterile (e.g., mules, hybrids made by crossing horses and donkeys), or just plain unusual (e.g., tigrons, which have occasionally been generated by hybridizing tigers and lions, or ligers, produced vice versa). Hybrids are genetic mixtures, with essentially all body cells containing equal quantities of DNA from each parent. This, of course, is true of all sexually produced individuals, it’s just that with hybrids, those two parents are likely to be more distantly related than is usual.
These days, a humanzee or chimphuman is not beyond imagining.
Chimeras, on the other hand, are somewhat different. They derive from what is essentially a process of grafting, whereby two genetic lines (most interestingly, different species) are combined to produce an individual that is partly of one genotype and partly of another, depending on which cells are sampled, and at what point in embryonic development. Probably because it is easier to imagine creatures produced by combining identifiable body parts from different animals than to picture a mingled, intermediate form, chimeras, more than hybrids, have long populated the human imagination. Ganesh, the Hindu god with a human body and elephant’s head, is a chimera, as are the horse-human centaurs of Western mythology. The classic “chimera” of Greek legend had the head and body of a lion, a tail that had morphed into the head of a snake and—to make a weird creature even more so—the head of a goat, sometimes facing forward and sometimes backward.
It is unclear whether my own imagined chimphuman will be a hybrid (produced by cross-fertilizing human and non-human gametes), or a chimera, created in a laboratory via techniques of genetic manipulation. I’m betting on the latter. Either way, human-chimp mixtures aren’t a new idea.
During the 1920s, a Russian biologist with the marvelously Slavic name Ilya Ivanovich Ivanov appears to have made the first serious, scientifically informed efforts to create a genetic hybrid between chimpanzees and human beings. Ivanov had the perfect qualifications: Not only did he possess a special interest in creating interspecific hybrids, he was an early specialist in artificial insemination, who had achieved international renown as a successful pioneer when it came to horse breeding. Prior to his work, even the most prized stallions and mares were limited to reproducing by “natural cover”—i.e., the old-fashioned way, one mounting at a time. But Ivanov found that by appropriate and careful dilution of stallion semen, combined with adroit use of the equine equivalent of a turkey baster, he could generate as many as 500 foals from a single genetically well-endowed stallion. His achievement caused a worldwide sensation, but nothing compared to what he next attempted.
It happened initially at the Research Institute of Medical Primatology, the oldest primate research center in the world, located at Sukhumi, the capital of Abkhasia, currently a disputed region in the state of Georgia, along the Black Sea. At one time, the Sukhumi Institute was the largest facility conducting research on primates. Not coincidentally, Stalin is believed to have been interested in such efforts, with an eye toward developing the “new Soviet man” (or half-man, or half-woman).
Nor was Soviet interest in combining human and nonhuman genetic material limited to Russian biologists. The novelist Mikhail Bulgakov, best known—at least in the West—for his fantasy, The Master and Margarita, also wrote Heart of a Dog, a biting satire on early Soviet-era social climbers, in which a pituitary gland from a drunken person is implanted into a stray dog, who subsequently becomes more and more human—although not noticeably more humane as he proceeds to eliminate all “vagrant quadrupeds” (cats) from the city. Maxim Gorky was on board, writing approvingly that Lenin and his Bolshevik allies were “producing a most severe scientific experiment on the body of Russia,” which would eventually achieve “the modification of human material.”
Similar modification became a staple of Soviet biology, as well, as when S.A. Voronov attempted “rejuvenation therapy,” a series of failed attempts to restore sexual function in rich, elderly men by transplanting slices of ape testes. But it was Ivanov who made the most serious efforts at combining human and nonhuman apes. Earlier in his career, in addition to the successful artificial insemination of horses, Ivanov had created a variety of animal hybrids, including “zeedonks” (zebras + donkeys) and different combinations of small rodents (mice, rats, and guinea pigs). For a time in the 1990s a fictional version of Ivanov was the chief character in a Russian-era television show portraying him as the “Red Frankenstein.”
In 1910, Ivanov had announced, at a World Congress of Zoologists in Graz, Austria, that it might be possible to produce a human-ape hybrid via artificial insemination. During the mid-1920s, working at a laboratory in Conakry (then part of French Guinea) under the auspices of France’s highly respected Pasteur Institute, Ivanov attempted just that, seeking without success to inseminate female chimpanzees with human sperm. (We don’t know whose, and we also presume—although don’t know for certain—that the attempted insemination was by artificial rather than natural means.) Then, in 1929, at the newly established Sukhumi Primate Research Institute, he endeavored to reverse donor and recipient, having obtained consent from five women volunteers to be inseminated—once again, presumably by artificial methods rather than “natural cover”—with sperm from chimpanzees and orangutans. Inconveniently, however, the nonhuman primate donors died before making their “donations,” and for reasons that are unclear, Ivanov himself fell out of political favor and was sent to Siberia in 1930; he died a few years later.
All sorts of things can be done; whether they should, is another question.
No one knows precisely what motivated Ilya Ivanov’s early fertilization experiments. Maybe it was the allure of the possible, such that having discovered the potent hybrid-generating hammer of in vitro fertilization, everything—including eggs and sperm, with one from human and the counterpart from nonhuman primates—looked alluringly like a nail. Or maybe he was driven by the prospect of currying favor with Stalin, or of fame (or infamy) had he succeeded, or perhaps as an ardent atheist Bolshevik Ivanov was inspired by the prospect of disproving religious dogma.
In any event, Ivanov’s story is not especially well known outside Russia, and insofar as Westerners learn of it, they are inclined to ridicule it as an absurd episode of reaching for a would-be “planet of the (communist) apes,” or to inveigh against the immorality of such at attempt, which is increasingly feasible. To be sure, his crude efforts at cross-species hybridization are at present no closer to fruition, simply because even though human and chimp DNA are overwhelmingly similar, humans have 46 chromosomes whereas chimps have 48, so getting sperm from either species to combine with eggs from the other to produce viable offspring is—to put it literally—inconceivable.
These days, however, a humanzee or chimphuman is not beyond imagining. There have been many advances in biomedical research that not only emphasize the continuity between human beings and other animals, but that do so explicitly in the interest of human betterment. Research efforts are currently underway seeking to produce organs (kidneys, livers, etc.) that develop within an animal’s body—pigs are the preferred target species—and whose genetic fingerprints are sufficiently close to the Homo sapiens counterpart to be accepted by a human recipient’s immune system, while also able to function in lieu of the recipient’s damaged organ. A human skin cell, for example, can be biochemically induced to become a “pluripotent stem cell,” capable of differentiating into any human tissue type. If, say, a replacement liver is desired, these stem cells can be introduced into a pig embryo after first using CRISPR to inactivate the embryo’s liver-producing genes. If all goes well, the resulting pig-human chimera will have the body of a pig, but containing an essentially human liver, which would then be available for transplantation into a person whose liver is failing.
After years of opposition, the U.S. National Institutes of Health announced in August, 2016 that it intends to lift its moratorium on stem cell research, which holds out promise for treating (perhaps even curing) many serious human diseases, such as cirrhosis, diabetes, and Parkinson’s. Currently prohibited—and likely to remain so—is funding for studies that involve injecting human stem cells into embryonic primates, although inserting such cells into adults is permissible. Insofar as there is a biological line separating human beings from other species, it should be clear that this line is definitely permeable, not hard and fast, and is based more on ethical and political judgment than on science or technology. All sorts of things can be done; whether they should, is another question.
Looking favorably on the prospect of a humanzee or chimphuman will likely be not only controversial, but to many people, downright immoral. But I propose that generating humanzees or chimphumans would be not only ethical, but profoundly so, even if there were no prospects of enhancing human welfare. How could even the most determinedly homo-centric, animal-denigrating religious fundamentalist maintain that God created us in his image and that we and we alone harbor a spark of the divine, distinct from all other life forms, once confronted with living beings that are indisputably intermediate between human and non-human?
In any event, the nonsensical insistence that human beings are uniquely created in God’s image and endowed with a soul, whereas other living things are mere brutes has not only permitted but encouraged an attitude toward the natural world in general and other animals in particular that has been at best indifferent and more often, downright antagonistic, jingoistic, and in many cases, intolerably cruel. It is only because of this self-serving myth that some people have been able to justify keeping other animals in such hideous conditions as factory farms in which they are literally unable to turn around, not to mention prevented from experiencing anything approaching a fulfilling life. It is only because of this self-serving myth that some people accord the embryos of Homo sapiens a special place as persons-in-waiting, magically endowed with a notable humanity that entitles them to special legal and moral consideration unavailable to our nonhuman kin. It is only because of this self-serving myth that many people have been able to deny the screamingly evident evolutionary connectedness between themselves and other life forms.
When claims are made about the “right to life,” invariably the referent is human life, a rigid distinction only possible because of the presumption that human life is somehow uniquely distinct from other forms of life, even though everything we know of biology demonstrates that this is simply untrue. What better, clearer, and more unambiguous way to demonstrate this than by creating viable organisms that are neither human nor animal but certifiably intermediate?
but wouldnt the blind following the blind get lost?Flat earthers should be given the credit they deserve.
For years scientists have wanted to go to the sun to study it close up. But they could not because of the intense heat.
Finally flat earthers solved the age old problem, they will just go at night.