The salmon vs. Darwin

Another Fine-Tuned Mechanism Gets Salmon Home

Evolution News & Views March

What is carbonic anhydrase and why does it matter? The presence of this enzyme in salmon hearts points to another case of intelligent design in these remarkable fish that were depicted in Illustra Media's film Living Waters. News via the Journal of Experimental Biology explains the challenge salmon face swimming upstream:

Fish plumbing is contrary. As the heart is the last organ that blood passes through before it returns to the gills, and with little direct blood supply to the ceaselessly contracting muscle, there are occasions when it could be on the verge of failure. 'We know this can happen under certain conditions like exhaustive exercise in combination with hypoxia or elevated water temperature', says Sarah Alderman from the University of Guelph, Canada. Added to the challenge of keeping the heart supplied with oxygen, Alderman explains that the haemoglobin that carries oxygen in fish blood is finely tuned to blood pH: the more acidic the red blood cells, the less able haemoglobin is to carry oxygen, which could prevent the red blood cells of exercising fish from picking up oxygen at the gills if they didn't have an effective pump to remove acid from the cells and restore the pH balance. [Emphasis added.]

Here we see a double challenge the salmon faces. It has to avoid excess acid so that the hemoglobin can carry oxygen, and it has to get the oxygen all the way from the gills through its entire body to the heart. Here's where carbonic anhydrase comes to the rescue:

But Alderman and her colleagues, Till Harter, Tony Farrell and Colin Brauner from the University of British Columbia, Canada, also knew that fish can take advantage of a sudden drop in red blood cell pH to release oxygen rapidly at tissues -- such as red muscle and the retina -- when required urgently. An enzyme called carbonic anhydrase -- which combines CO2 and water to produce bicarbonate and acidic protons, and vice versa -- lies at the heart of this mechanism. Normally there is no carbonic anhydrase in blood plasma; however, the enzyme has been found in salmon red muscle capillaries, where it facilitates the reaction of protons -- that have been extruded from the red blood cell -- with bicarbonate to produce CO2, which then diffuses back into the red blood cell. The CO2 is then converted back into bicarbonate and protons in the blood cell, causing the pH to plummet and release a burst of O2 from the haemoglobin. Could salmon take advantage of this mechanism to boost oxygen supplies to the heart when the animals are working full out? Possibly, but only if carbonic anhydrase was accessible to blood passing through the heart.What is carbonic anhydrase and why does it matter? The presence of this enzyme in salmon hearts points to another case of intelligent design in these remarkable fish that were depicted in Illustra Media's film Living Waters. News via the Journal of Experimental Biology explains the challenge salmon face swimming upstream:

Fish plumbing is contrary. As the heart is the last organ that blood passes through before it returns to the gills, and with little direct blood supply to the ceaselessly contracting muscle, there are occasions when it could be on the verge of failure. 'We know this can happen under certain conditions like exhaustive exercise in combination with hypoxia or elevated water temperature', says Sarah Alderman from the University of Guelph, Canada. Added to the challenge of keeping the heart supplied with oxygen, Alderman explains that the haemoglobin that carries oxygen in fish blood is finely tuned to blood pH: the more acidic the red blood cells, the less able haemoglobin is to carry oxygen, which could prevent the red blood cells of exercising fish from picking up oxygen at the gills if they didn't have an effective pump to remove acid from the cells and restore the pH balance. [Emphasis added.]

Here we see a double challenge the salmon faces. It has to avoid excess acid so that the hemoglobin can carry oxygen, and it has to get the oxygen all the way from the gills through its entire body to the heart. Here's where carbonic anhydrase comes to the rescue:

But Alderman and her colleagues, Till Harter, Tony Farrell and Colin Brauner from the University of British Columbia, Canada, also knew that fish can take advantage of a sudden drop in red blood cell pH to release oxygen rapidly at tissues -- such as red muscle and the retina -- when required urgently. An enzyme called carbonic anhydrase -- which combines CO2 and water to produce bicarbonate and acidic protons, and vice versa -- lies at the heart of this mechanism. Normally there is no carbonic anhydrase in blood plasma; however, the enzyme has been found in salmon red muscle capillaries, where it facilitates the reaction of protons -- that have been extruded from the red blood cell -- with bicarbonate to produce CO2, which then diffuses back into the red blood cell. The CO2 is then converted back into bicarbonate and protons in the blood cell, causing the pH to plummet and release a burst of O2 from the haemoglobin. Could salmon take advantage of this mechanism to boost oxygen supplies to the heart when the animals are working full out? Possibly, but only if carbonic anhydrase was accessible to blood passing through the heart.

Well, what do you know! That's what Alderman's team found: the enzyme is present on the surface of the heart chambers. Using the heart itself as their "reaction vessel," they were able to see the pH plummet as the enzymes went into gear. 

Working closely together, the duo painstakingly developed a technique where they could measure the pH in the beating heart with pH probes that were thinner than a human hair. Eventually, the duo's persistence paid off and the pH in the heart plummeted as they fed CO2 into the pulsating chambers. And when they added a carbonic anhydrase inhibitor (produced by Claudia Supuran) to the fluid, the pH fall slowed dramatically. Carbonic anhydrase was responsible for the drop in pH.

The Protein Data Bank 101 website shows pictures of this enzyme and describes its mode of action. 

An enzyme present in red blood cells, carbonic anhydrase, aids in the conversion of carbon dioxide to carbonic acid and bicarbonate ions. When red blood cells reach the lungs, the same enzyme helps to convert the bicarbonate ions back to carbon dioxide, which we breathe out. Although these reactions can occur even without the enzyme, carbonic anhydrase can increase the rate of these conversions up to a million fold.

There's an evolutionary conundrum about this enzyme: functional equivalence without sequence similarity:

This ancient enzyme has three distinct classes (called alpha, beta and gamma carbonic anhydrase). Members of these different classes share very little sequence or structural similarity, yet they all perform the same function and require a zinc ion at the active site. Carbonic anhydrase from mammals belong to the alpha class, the plant enzymes belong to the beta class, while the enzyme from methane-producing bacteria that grow in hot springs forms the gamma class. Thus it is apparent that these enzyme classes have evolved independently to create a similar enzyme active site.

Further complicating the picture, there are different forms of the enzymes depending on the tissue or cellular compartment they are located in. These allow fine tuning of the enzyme's activity: "Thus isozymes found in some muscle fibers have low enzyme activity compared to that secreted by salivary glands," in the case of mammals.Carbonic anhydrase (CA) was the first enzyme found to contain zinc, abiochemistry textbook says; now, hundreds are known. Zinc and other metals are often essential for function in metalloenzymes. The PDB-101 article explains,

Zinc is the key to this enzyme reaction. The water bound to the zinc ion is actually broken down to a proton and hydroxyl ion. Since zinc is a positively charged ion, it stabilizes the negatively charged hydroxyl ion so that it is ready to attack the carbon dioxide.

It's not surprising that this enzyme is present in the salmon, since it exists in all three domains of life. What's amazing is that the salmon's heart is studded with these enzymes that are "at the ready" when the large fish is fighting with all its might to leap above cascades and waterfalls, facing daunting challenges without the benefit of food. (Living Waters says, "The sockeye are so focused on their objective that after leaving the ocean, they do not eat again.")

If the pH dropped too early as the blood travels through the salmon's body, it would be less able to carry its precious oxygen cargo. But right when it is needed during that Olympic high jump over a waterfall or away from a hungry bear, the fish uses its CA enzymes in its heart to drop the pH and release the oxygen it needs. The spent blood then travels to the gills to load up with more oxygen. In the original paper in the Journal of Experimental Biology, the authors summarize what they found:

Combined, these results support our hypothesis of thepresence of an enhanced oxygen delivery system in the lumen of a salmonid heart, which could help support oxygen delivery when the oxygen content of venous blood becomes greatly reduced, such as after burst exercise and duringenvironmental hypoxia.

How many independent systems do we see at work in the remarkable migration of the salmon? The fish has a built-in map of its destination. It has the ability to memorize waypoints by smell. It can navigate by the earth's magnetic field. It has a sixth sense, the lateral line. It can distinguish odors by parts per trillion. Each of its body systems contain thousands of molecular machines like carbonic anhydrase that are located just where they need to be, doing what they need to do to support the whole organism.

If any one of these systems is a testament to intelligent design, how much more the composite? The only fish story here is the notion that all this came together by unguided natural processes -- sheer dumb luck.

On taking on big science's gatekeepers.

Is There a Scientific Establishment?

David Klinghoffer March 15, 2016 4:30 PM

The term "Establishment" is controversial. It invariably implies a critical stance, suggesting a system, a power structure, in need of a shakeup or worse. It's not a description anyone would welcome having applied to himself. Nobody wants to be seen as defending entrenched privilege. Depending on the context, some deny the existence of such an entity to begin with.

What about in the world of science, and specifically biology? Is it fair to speak of an Establishment there, primed to be updated by "rogue" outside forces? It seems so. Or perhaps "rigidly calcified mindset" is the better phrase. Today in the New York Times, Amy Harmon reports on hints of decalcification, a modest but significant move in science research publishing toward "preprints." That is, publishing directly online without first submitting your work to the official gatekeepers: peer-reviewed journals.

Don't worry -- it's not as if this research then goes unreviewed or uncriticized. Instead the review process happens immediately and organically. Those interested enough to read your work can tell anyone and everyone what they think. Minus the online aspect, it's the way Charles Darwin published his ideas:

On Feb. 29, Carol Greider of Johns Hopkins University became the third Nobel Prize laureate biologist in a month to do something long considered taboo among biomedical researchers: She posted a report of her recent discoveries to a publicly accessible website, bioRxiv, before submitting it to a scholarly journal to review for "official'' publication.

It was a small act of information age defiance, and perhaps also a bit of a throwback, somewhat analogous to Stephen King's 2000 self-publishing an e-book or Radiohead's 2007 release of a download-only record without a label. To commemorate it, she tweeted the website's confirmation under the hashtag #ASAPbio, a newly coined rallying cry of a cadre of biologists who say they want to speed science by making a key change in the way it is published.

Such postings are known as "preprints'' to signify their early-stage status, and the 2,048 deposited on three-year-old bioRxiv over the last year represent a barely detectable fraction of the million or so research papers published annually in traditional biomedical journals.

But after several dozen biologists vowed to rally around preprints at an "ASAPbio'' meeting last month, the site has had a small surge, and not just from scientists whose august stature protects them from risk. On Twitter, preprint insurgents are celebrating one another's postings and jockeying for revolutionary credibility.

One diagnostic of a genuine Establishment would be that its members maintain that the system, for everyone's good, couldn't be much different from how it is. In this case, there's nothing necessary about the traditional manner in which biologists publish their work. Physics, as Harmon notes, has had preprints for decades, and the field is healthier for it:

Unlike physicists, for whom preprints became a default method of communicating discoveries in the 1990s, biomedical researchers typically wait more than six monthsto disseminate their work while they submit it -- on an exclusive basis -- to the most prestigious journal they think might accept it for publication. If, as is often the case, it is rejected, they try another journal. As a result, it can sometimes take years to publish a paper, which is then typically available for a time only to colleagues at major academic institutions whose libraries pay for subscriptions. And because science is in many ways a relay, with one scientist building on the published work of another, the communication delays almost certainly slow scientific progress.

True, it's not that preprints are intended to replace traditional publishing. Those interviewed for the article are careful to say they aren't rejecting the big journals. You wouldn't want to offend the Establishment!

Many have taken pains to reiterate their wish not to disrupt the journal system, only to enhance it. With enough scientists pushing to legitimize preprints, they hope journals will allow the systems to coexist.

"It's not beer or tacos," as James Fraser, an assistant professor at the University of California, San Francisco put itat last month's conference, "it's beer AND tacos."

Still, this sounds exactly like a revolt, if mild, seeking to slip out from under some of the bonds of a burdensome hierarchy -- one that up till now has controlled the flow of ideas and artificially constrained debate through access and credentialing, with an eye to maintaining its own power and prestige. What will it mean for insurgent scientific ideas like intelligent design and the critique of Darwinism? Time will tell, but the development seems like a hopeful one.

Yet more on pre evolutionary design.

Collective Motion: A New Level of Design Found in Proteins

Evolution News & Views March 15, 2016 3:06 AM

A "previously unidentified mechanism for modulating protein affinity" has come to light. A team of scientists at the Max Planck Institute for Biochemical Chemistry, publishing in the Proceedings of the National Academy of Sciences, has identified new functional roles for collective motions within protein molecules. These motions, referred to as allostery, allow one end of the protein to affect a distant part through what is termed "allosteric communication."

Intermolecular interactions are one of the key mechanismsby which proteins mediate their biological functions. For many proteins, these interactions are enhanced or suppressed by allosteric networks that couple distant regions together. The mechanisms by which these networks function are just starting to be understood, and many of the important details have yet to be uncovered. In particular, the role of intrinsic protein motion and kinetics remains particularly poorly characterized. [Emphasis added.]

This is cutting-edge research. The team studied a common protein named ubiquitin which, as the name implies, is ubiquitous in the cell. It serves as a molecular "tag" on other molecules slated for degradation by the proteasome. As such, it needs to form connections with the proteasome and with a variety of other proteins. What they found is that distant parts of the molecule could affect binding affinity of other parts through motions transmitted throughout the entire molecule.

To determine how this collective motion influences bindingand other functions of ubiquitin (e.g., presence of different covalent linkages), we performed an extensive structural bioinformatics survey of known ubiquitin crystal structures. Because the peptide bond conformation was the most recognizable feature of the collective mode, we used its conformation as a "marker" for structural discrimination. Themost significant relationship we found was the universal association between the NH-in state and binding to the ubiquitin-specific protease (USP) family of deubiquitinases (Fig. S11). This association has been previously noted and issurprising because the peptide bond is at least 6.8 Å from any USP (Fig. 3A).

By comparing mutants with wild-type forms, the team found several kinds of motion that involve twisting, rocking and stretching. Mutations on a peptide bond between two specific amino acid residues, in particular, had a surprising effect, reducing binding affinity by a factor of 10 (or abolishing it altogether). This suggests low tolerance for mutation.

They found "strong allosteric coupling between opposite sides of the protein" in some cases. "Given the relative subtlety of the expansion and contraction" of allosteric interactions, they found it "surprising" again that two different states could produce large effects. It implies that ubiquitin and its ligand "appear to adapt their conformations mutually to establish a complementary binding interaction" for best fit at the appropriate times.

One mutant showed a two-fold weaker affinity for its particular USP. "Although this change may seem like a moderate effect," they note, "it isactually surprisingly large and highly significant when one considers that it is allosterically triggered by the simple rotation of a solvent-exposed peptide bond on a distal side of the protein."

These motions are so rapid -- on the order of microseconds -- they were not really considered significant until recently. Other motions they mention, like "pincer time" and "tumbling time," occur on different time scales, the former being quicker, the latter being much slower. This may suggest a kind of timing code for different functions.

Their conclusions reveal a significant new area of study: switch-controlled "allosteric communication" in protein molecules:

This study revealed an allosteric switch affecting protein-protein binding through collective protein motion at the microsecond time scale.... Whereas most known microsecond to millisecond time-scale motions involve excursions to excited, lowly populated states, this motion occurs between two ground state ensembles with nearly equal populations (NH-in and NHout). Strikingly, the peptide bond conformation is allosterically coupled through a diverse set of interactions that triggers contraction/ expansion of the entire domain. This type of global domain motion reveals apreviously unidentified mechanism for modulating protein affinity. The presence of this allosteric network suggeststhere may be heretofore undiscovered ways in which macromolecular assemblies and covalent linkages regulate ubiquitin binding. More broadly, this study demonstrates how relatively modest changes in hydrogen bond networks and the protein backbone can bring about distant changes in protein conformation and binding affinity.

We encounter, therefore, a whole new level of specificity in protein architecture. It's not the old picture of an active site surrounded by haphazard amino acid residues. Any change could affect the allosteric communication of the whole protein. Clearly, mutants were less able to take advantage of the benefits of collective motion.

How did an unguided process arrive at a molecular machine that not only grips its substrate and catalyzes a reaction efficiently, but moves with intrinsic twists and stretches to improve the grip? The design specs for proteins just shot up a notch, and along with them, the challenges to Darwinian evolution.

On Charles Darwin and Rube Goldberg

My Debate with Michael Ruse -- Evolution as a Rube Goldberg Machine

Cornelius Hunter March 17, 2016 3:32 AM 

Editor's note: Evolution News is delighted to welcome back Dr. Hunter as a contributor. He is a Fellow with the Center for Science & Culture, Adjunct Professor at Biola University, and author of the award-winning Darwin's God: Evolution and the Problem of Evil. He blogs at Darwin's God

It was great to see Professor Michael Ruse again last week in Northern California for our debate on the question, "Is Evolution Compelling?" He was in good spirits as usual, and his jokes were much better than mine. But I had one big advantage over my erudite opponent: I was not defending the age-old idea that the world of life arose by chance. The main problem, as I explained at the outset, is that the scientific evidence contradicts unguided evolution. That is a very simple point, but it opens new worlds of thought.

I used my time to discuss a range of scientific evidence from biology. On that evidence, unguided evolution simply makes no sense. But I almost hesitate to show you my list simply because there is nothing special about it. One of the difficulties in explaining the problems with evolution to an audience is the plethora of examples from which to choose. I had a long list of fascinating biological designs that refute evolutionary thought. I like every one of them, because they all add a different angle on why evolution fails. But there are far too many to fit into an evening's presentation. I was changing my mind right up to the last day, but as difficult as it is, one must pare back the list to fit the time constraint.

I began with one of my favorites, micro RNA. I then discussed the failure of evolution's nested hierarchy. Later I had fun with echolocation and the DNA code, and I finished with directed adaptation. The obvious and unavoidable truth is that evolution is believed to be a fact not because of the science, but despite the science.

I also punctuated my scientific examples with some philosophy of science concerns. One of them is the problem of parsimony. I explained Occam's Razor, and how a sure sign of a failing theory is if it becomes overly complicated. The appeal of heliocentrism over geocentrism was not that of an improvement in accuracy, but in simplicity. Like heliocentrism, Copernicus' geocentrism had epicycles. So why make the move? Because Copernicus was able to use fewer epicycles. That is how important simplicity is in science.

Theory complexity is the enemy in science, and it would require volumes to explain all the details in today's theory of evolution. The reason why evolution is so complicated is that with each scientific failure, the theory is adjusted yet again. Today it resembles one of Rube Goldberg's wonderful machines.

For this theory, there is no ray of hope. I think I left the audience convinced that evolution is an utterly failed attempt. That's not because of any rhetorical skills on my part, but simply because I took the side of science. This isn't at all complicated. What is complicated is the question of why people believe in evolution to begin with. But that's another story.

On the hunt for the biggest cryptid of them all.

Are Black Holes Real?

By Kate Becker on Thu, 10 Mar 2016

Not so long ago, black holes were like unicorns: fantastical creatures that flourished on paper, not in life. Today, there is wide scientific consensus that black holes are real. Even though they can’t be observed directly—by definition, they give off no light—astronomers can infer their hidden presence by watching how stars, gas, and dust swirl and glow around them.

But what if they’re wrong? Could something else—massive, dense, all-but-invisible—be concealed in the darkness?

A telescope as big as the Earth could tell a black hole from an exotic imposter.

While black holes have gone mainstream, a handful of researchers are investigating exotic ultra-compact stars that, they argue, would look exactly like black holes from afar. Well, almost exactly. Though their ideas have been around for many years, researchers are now putting them to the most stringent tests ever, looking to show once and for all that what looks and quacks like a black hole really is a black hole. And if not? Well, it could just spark the next revolution in physics.

The game-changer is a new experiment called the Event Horizon Telescope (EHT). The EHT is a network of telescopes that are sensitive to radio waves about a millimeter long and linked together using a technique called very long baseline interferometry. Baseline refers to the distance between the networked telescopes: the longer the distance, the finer the details the telescope can pick out. It’s impossible—or at least impractical—to build a single telescope as big as planet Earth, but astronomers can achieve the same “zoom” factor by linking telescopes on opposite continents. Just like that, the universe goes from standard-definition to HD: a switch powerful enough to tell a black hole from an exotic imposter.

Meanwhile, scientists have directly detected gravitational waves for the first timeusing the Laser Interferometer Gravitational-Wave Observatory, also known as LIGO. Gravitational waves—ripples in the fabric of space-time that Einstein predicted should radiate out from the site of any gravitational disturbance—represent an entirely new way to see the cosmos, and with enough data, they could finally confirm—or contradict—the existence of black holes.

Black Hole Anatomy

On its own, a black hole looks like nothing: black-on-black, indistinguishable from the empty space that surrounds it. But supermassive black holes, which are believed to sit at the core of almost every galaxy in the universe, surrounded by stars and other galactic detritus that accumulates around the edge like soap suds circling the bathtub drain. By studying those “suds,” astronomers can answer questions about the central black hole.

The best-studied black hole candidate in the universe is the one called Sagittarius A*, which lives at the center of our very own Milky Way galaxy. By tracking the orbits of stars circling around Sagittarius A*, they have deduced that Sagittarius A* packs some 4 million times the mass of the Sun into a region of space much smaller than the solar system. Their conclusion: it could only be a supermassive black hole.To confirm that suspicion, they would like to see up to the edge of the black hole—the event horizon, a sort of line in the sand that separates the “inside” of the black hole from the “outside” and beyond which nothing can escape. From the perspective of a telescope on Earth, the event horizon should look like a dark shadow surrounded by a bright ring of light. The exact shape of this ring and shadow are predicted by the equations of general relativity, plus the properties of the black hole and its surroundings.

An Earth-Sized Telescope

That’s where the EHT comes in. Since the EHT first started taking data, it has been building its telescope roster, and with each new member, it gets closer to making the first true image of a black hole shadow.

The EHT is like an all-star team of telescopes: Most days, its millimeter-wave dishes run their own experiments independently, but for one or two weeks a year, they team up to become the EHT, taking new data and running tests during the brief window when astronomers can expect clear weather at sites from Hawaii to Europe to the South Pole.

“It sounds too good to be true that you just drop telescopes around the world and ‘poof!’ you have an Earth-sized telescope,” says Avery Broderick, a theoretical astrophysicist at University of Waterloo and the Perimeter Institute. And in a way, it is. The EHT doesn’t make pictures. Instead, it turns out a kind of mathematical cipher called a Fourier transform, which is like the graphic equalizer on your stereo: it divvies up the incoming signal, whether its an image of space or a piece of music, into the different frequencies that make it up and tells you how much power is stored in each frequency. So far, the EHT has only given astronomers a look at a few scattered pixels of the Fourier transform. When they compare those pixels to what they expect to see in the case of a true black hole, they find a good match. But the job is like trying to figure out whether you’re listening to Beethoven or the Beastie Boys based only on a few slivers of the graphic equalizer curve.

Black holes are mothers of cosmic paradox.

Now, the EHT is about to add a superstar player: the Atacama Large Millimeter Array, a telescope made up of 66 high-precision dishes sited 16,000 feet above sea level in Chile’s clear, dry Atacama desert. With ALMA on board, the EHT will finally be able to make the leap from fitting models to seeing a complete picture of the black hole’s shadow. EHT astronomers are now rounding up time at all of the telescopes so that they can take new data and assemble that first coveted image in 2017.

And if they don’t see what they expect? It could mean that the black hole isn’t really a black hole at all.

That would come as a relief to many theorists. Black holes are mothers of cosmic paradox, keeping physicists up at night with the puzzles they present: Do black holes really destroy information? Do they really contain infinitely dense points called singularities? Black holes are also the battlefield on which general relativity and quantum mechanics clash most dramatically. If it turns out that they don’t actually exist, some physicists might sleep a little better.

But if they’re not black holes, then what could they be? One possibility is that they are dark stars made up of bosons, subatomic particles that, unlike more familiar electrons and protons, obey strange rules that allow more than one of them to be in the same place at the same time. Boson stars are highly speculative—astronomers have never seen one, as far as they know—but theorists like Vitor Cardoso, a professor of physics at Técnico in Lisbon and a distinguished visiting researcher at Sapienza University of Rome, hypothesize that some or all of the objects we think are supermassive black holes could actually be boson stars in disguise.

Physicists classify particles into two different categories: fermions, which include protons, electrons, neutrons, and their components; and bosons, like photons (light particles), gluons, and Higgs particles. Every star that we’ve ever seen shining is dominated by fermions. But, Cardoso says, given a starting environment rich in bosons, bosons could “clump” together gravitationally to form stars, just as fermions do. The early universe might have had a high enough density of bosons for boson stars to form.

But not every boson is a suitable building block for a boson star. Gravity won’t hold together a clump of massless photons, for instance. Higgs particles are massive enough to be bound together by gravity, but they aren’t stable—they only exist for tiny fraction of a second before decaying away. Theorists have speculated about ways to stabilize Higgs particles, but Cardoso is more intrigued by the prospect that other, yet-undiscovered heavy bosons, like axions, could make up boson stars. In fact, some physicists hypothesize that massive bosons like these could be responsible for dark matter—meaning that boson stars wouldn’t just be a solution to the riddle of black holes, they could also tell us what, exactly, dark matter is.

Gravastars

Boson stars aren’t the only black hole doppelgänger that theorists have dreamed up. In 2001, researchers proposed an even more speculative oddity called a gravastar. In the gravastar model, as a would-be black hole collapses under its own weight, extreme gravity combines with quantum fluctuations that are constantly jiggling through space to create a bubble of exotic spacetime that halts the cave-in.

Theorists don’t really know what’s inside that bubble, which is both good and bad news for gravastars: Good news because it gives theorists the flexibility to revise the model as new observations come in, bad news because scientists are rightly skeptical of any model that can be patched up to match the data.

When the data does come in, physicists have a checklist of sorts that should help them know which of the three—black hole, boson star, or gravastar—they’re looking at. A gravastar should have a bright surface that’s distinguishable from the glowing ring predicted to loop around a black hole. Meanwhile, if the object at the center of the Milky Way is actually a boson star, Cardoso predicts, it will look more like a “normal” star. “Black holes are black all the way through,” Cardoso says. “If really the object is a boson star, then the luminous material can in principle pile up at its center. A bright spot should be detected right at the center of the object.”

A New View

Most physicists have placed their bets on Saggitarius A* and other candidates being black holes, though. Boson stars and gravastars already have a few strikes against them. First, when it comes to scientific credibility, black holes have a major head start. Astronomers have a solid understanding of the process by which black holes form and have direct evidence that other ultra-dense objects, like white dwarfs and neutron stars, which could merge to form black holes, really do exist. The alternatives are more speculative on every count.

Furthermore, Broderick says, astronomers have looked for the telltale signature of boson stars and gravastars at the center of the Milky Way—and haven’t found it. “The stuff raining down on the object will give up all its kinetic energy—all the gravitational binding energy tied up in the kinetic energy of its fall—resulting in a thermal bump in the spectrum,” Broderick says —that is, a signature spike in infrared emission. In 2009, astrophysicists reported that they had found no such bump coming from Sagittarius A*, and in 2015, they announced that it was missing from the nearby massive galaxy M87, too.

“To confirm or rule out boson stars entirely, we need ‘louder’ observations.”

Cardoso doesn’t see this as a death-knell for the boson star model, though. “The field that makes up the boson star hardly interacts with matter,” he says. To ordinary matter, the surface of a boson star would feel like frothed milk. “We do not yet have a complete model of how these objects accrete luminous matter,” Cardoso says, “so I think that it’s fair to say that this is still an open question.” He is less optimistic about gravastars, which he describes as “artificial constructs” that are likely ruled out by the latest observations.

As the LIGO experiment gathers more data, theorists will get more opportunities to test their exotic hypotheses with gravitational waves. As two massive objects—say, a supermassive black hole and a star—spiral toward each other on the way toward a collision, gravitational waves carry away the energy of their motion. If one member of the spiraling pair is a black hole, the gravitational wave signal will cut off abruptly as the star passes through the black hole’s event horizon. “It gives rise to a very characteristic ringdown in the final stages of the inspiral,” Cardoso says. Because the alternative models have no such horizon, the gravitational wave signal would keep on reverberating.

Most astronomers believe that the waves LIGO detected were given off by the collision of two black holes, but Cardoso thinks that boson stars shouldn’t be ruled out just yet. “The data is, in principle, compatible with the two colliding objects being each a boson star,” he says. The end result, though, is probably a black hole “because it rings down very fast.”

LIGO is not designed to pick up signals at the frequency at which supermassive objects like Sagittarius A* are expected to “ring.” (LIGO is tuned to recognize gravitational waves from smaller black holes and dense stars like neutron stars.) But supermassive black holes and boson stars are in the sweet spot for the planned space-based gravitational wave telescope eLISA (the Evolved Laser Interferometer Space Antenna), slated for launch in 2034. “To confirm or rule out boson stars entirely, we need ‘louder’ observations,” Cardoso says. “EHT or eLISA are probably our best bet.”

Taking the Pulse

In the meantime, astronomers could measure waves from these extremely massive objects by precisely clocking the arrival times of radio pulses from a special class of dead stars called pulsars. If astronomers spot pulses arriving systematically off-beat, that could be a sign that the space they’ve been traveling across is being stretched and squeezed by gravitational waves. Three collaborations—NANOGrav in North America, the European Pulsar Timing Array, and the Parkes Pulsar Timing Array in Australia—are already scanning for these signals using radio telescopes scattered around the globe.

To Broderick, though, the big question isn’t which model will win out, it’s whether these new experiments can find a flaw in general relativity. “For 100 years, general relativity has been enormously successful, and there’s no hint of where it breaks,” he says. Yet general relativity and quantum mechanics, which appears equally shatterproof, are fundamentally incompatible. Somewhere, one or both must break down. But where? Boson stars and gravastars might not be the answer. Still, exploring these exotic possibilities forces physicists to ask the questions that might lead them to something even more profound.

“We expect that general relativity will pass the EHT’s tests with flying colors,” Broderick says. “But the great hope is that it won’t, that we’ll finally find the loose thread to pull on that will unravel the next great revolution in physics.”

Immortality on the cheap?

Your Personality Uploaded to a Robot Wouldn't Be "You"

Wesley J. Smith March 14, 2016 11:34 AM | 

Transhumanism is a materialistic religion that seeks to attain the comforts provided by faith through belief in technology as savior. One aspect of the movement is the quest for eternal life. Now, a hyper-rich Russian mogul hopes to live forever by uploading his personality to a robot. From the Telegraph story:

Web entrepreneur Dmitry Itskov is behind the "2045 Initiative", an ambitious experiment to bring about immortality within the next 30 years by creating a robot capable of storing human personalities.

The group of neuroscientists, robot builders and consciousness researchers say they can create an android that is capable of uploading someone's personality.

Mr Itskov, who has made a reported £1bn from his Moscow-based news publishing company, is the project's financial backer.

They believe that robots can store a person's thoughts and feelings because brains function in the same way as a computer.

Says Itskov, "Different scientists call it uploading or they call it mind transfer. I prefer to call it personality transfer."

Even if they could do this, however, so what? Whatever programming the robot was able to access, "Robot Itskov" still wouldn't be Itskov. Our beings are so much more than what we think and remember. For example, there are the subconscious, physical sensations caused by stimuli that trigger hormones and body chemicals, the experience of emotions, and for those who believe in such things, the spiritual element.

No matter how powerful the algorithms that governed an "immortality robot's" programming, it would exhibit -- at most -- a faux or mimicking of "personality." The person being mimicked -- the being the robot was supposed to have become -- would not be present.

How the evo devo revolution is undermining Darwinism. II

Internal Constraints vs. External Pressures: The Revelations of Evo-Devo

Michael Denton March 14, 2016 3:29 AM

Editor's note: In his new book Evolution: Still a Theory in Crisis, Michael Denton not only updates the argument from his groundbreaking Evolution: A Theory in Crisis (1985) but also presents a powerful new critique of Darwinian evolution. This article is one in a series in which Dr. Denton summarizes some of the most important points of the new book. For the full story, get your copy of Evolution: Still a Theory in Crisis. For a limited time, you'll enjoy a 30 percent discount at CreateSpace by using the discount codeQBDHMYJH.

One of the major advances since the publication of Evolution: A Theory in Crisis has been the revolutionary increase in our understanding of development and especially the genetics of development, about which little was known in 1985. These advances have led to the emergence of a whole new field, nicknamed "evo-devo" (evolutionary developmental biology). At the heart of the new field has been the discovery that a limited set of highly conserved genes, gene circuits, and developmental mechanisms -- for example, Hox genes, signaling proteins such as "sonic hedgehog," chemical gradients, and gene regulatory networks -- are involved in the construction of the bodies of all bilaterally symmetric animals,1 all the morphological homologs, and indeed all higher organismic form. Sean Carroll has termed this set of conserved genes and developmental mechanisms the "toolkit."2

One now well-established finding of evo-devo was totally unexpected from Darwinian first principles. It is that what are referred to by evo-devo researchers as "constraints," or what might also be termed "internal causal factors," have played a far more important role in the origin of many of the homologs and Bauplans than was previously envisaged. Before evo-devo it was widely thought that internal factors played little or no role in shaping the course of evolution. But it is now increasingly obvious that internal causal factors have played a far more prominent role in the actualization of evolutionary innovations than cumulative selection.

One of the most fundamental of all evolutionary innovations occurred when some ancestral chordate switched its body plan from the design previously shared by all other animal groups (in which the nerve chord is in a ventral position and the heart and main blood vessel are placed dorsally) to a design that was the exact reverse (in which the nerve chord is placed dorsally and the heart placed ventrally), and that has remained invariant in all chordates ever since. The evidence for this dorsal-ventral inversion (D-V) was revealed when evo-devo studies showed that the signaling molecules that specify the back of an insect also specify the ventral side (the belly) of a vertebrate.3 Before evo-devo revealed that the same genes were involved in specifying the dorsal-ventral axis of chordates and non-chordates, no one took seriously Goeffroy's suggestion, made early in the 19th century, that all animals shared the same basic body plan.

Self-evidently, Darwinian scenarios must confront the obvious question as to whether this transition was gradual or sudden. On the one hand, it is very hard to imagine how gradual cumulative selection could carry out such a radical re-engineering of the basic body plan. What mystifying adaptive path can be proposed along which such a gradual transition might have occurred? On the other hand, if the change occurred suddenly in one massive macro-mutational saltation, then Darwinian causation is ruled out of court altogether.

In the case of this dramatic innovation, the revelations of evo-devo provide no support at all for the Darwinian notion that cumulative selection is the major causal engine of evolutionary transitions.

In taxa-defining homologs, it is self-evident that the emerging evo-devo picture provides no support whatsoever for the Darwinian claim that novelties came about during the course of evolution to serve a succession of functional ends. In this case, the structuralist inference that internal constraints and not cumulative selection played the key role in their actualization is difficult to refuse.

This example is not atypical. Evo-devo advances have revealed that in many, if not the great majority, of innovations in the history of life,internal causal factors have played a predominant role. Against all traditional expectations, Darwinian selection to serve adaptive ends could only have played, in most cases, a relatively peripheral causalrole. Before evo-devo, no one would have imagined that a vast amount of organic order arises from internal constraints and causal factors within organisms themselves and is not imposed by selection. What was heresy only three decades ago is now accepted doctrine.

References:

(1) Lewis I. Held, How the Snake Lost Its Legs: Curious Tales from the Frontier of Evo-Devo (New York: Cambridge University Press, 2014), Chapter 1.

(2) Sean Carroll, Endless Forms Most Beautiful, Chapter 3, see fig. 3.7.

(3) Held, How the Snake Lost Its Legs, Chapter 1; for alternate scenarios, see "Inversion (evolutionary biology)," Wikipedia, Wikipedia Foundation Inc., March 22, 2015 (accessed on August 19, 2015).