Search Results for "bias"

Feb 12 2024

The Exoplanet Radius Gap

Published by under Astronomy

As of this writing, there are 5,573 confirmed exoplanets in 4,146 planetary systems. That is enough exoplanets, planets around stars other than our own sun, that we can do some statistics to describe what’s out there. One curious pattern that has emerged is a relative gap in the radii of exoplanets between 1.5 and 2.0 Earth radii. What is the significance, if any, of this gap?

First we have to consider if this is an artifact of our detection methods. The most common method astronomers use to detect exoplanets is the transit method – carefully observe a star over time precisely measuring its brightness. If a planet moves in front of the star, the brightness will dip, remain low while the planet transits, and then return to its baseline brightness. This produces a classic light curve that astronomers recognize as a planet orbiting that start in the plane of observation from the Earth. The first time such a dip is observed that is a suspected exoplanet, and if the same dip is seen again that confirms it. This also gives us the orbital period. This method is biased toward exoplanets with short periods, because they are easier to confirm. If an exoplanet has a period of 60 years, that would take 60 years to confirm, so we haven’t confirmed a lot of those.

There is also the wobble method. We can observe the path that a star takes through the sky. If that path wobbles in a regular pattern that is likely due to the gravitational tug from a large planet or other dark companion that is orbiting it. This method favors more massive planets closer to their parent star. Sometimes we can also directly observe exoplanets by blocking out their parent star and seeing the tiny bit of reflected light from the planet. This method favors large planets distant from their parent star. There are also a small number of exoplanets discovered through gravitational microlensing, and effect of general relativity.

None of these methods, however, explain the 1.5 to 2.0 radii gap. It’s also likely not a statistical fluke given the number of exoplanets we have discovered. Therefore it may be telling us something about planetary evolution. But there are lots of variables that determine the size of an exoplanet, so it can be difficult to pin down a single explanation.

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Feb 06 2024

Weaponized Pedantry and Reverse Gish Gallop

Published by under Logic/Philosophy

Have you ever been in a discussion where the person with whom you disagree dismisses your position because you got some tiny detail wrong or didn’t know the tiny detail? This is a common debating technique. For example, opponents of gun safety regulations will often use the relative ignorance of proponents regarding gun culture and technical details about guns to argue that they therefore don’t know what they are talking about and their position is invalid. But, at the same time, GMO opponents will often base their arguments on a misunderstanding of the science of genetics and genetic engineering.

Dismissing an argument because of an irrelevant detail is a form of informal logical fallacy. Someone can be mistaken about a detail while still being correct about a more general conclusion. You don’t have to understand the physics of the photoelectric effect to conclude that solar power is a useful form of green energy.

There are also some details that are not irrelevant, but may not change an ultimate conclusion. If someone thinks that industrial release of CO2 is driving climate change, but does not understand the scientific literature on climate sensitivity, that doesn’t make them wrong. But understanding climate sensitivity is important to the climate change debate, it just happens to align with what proponents of anthropogenic global warming are concluding. In this case you need to understand what climate sensitivity is, and what the science says about it, in order to understand and counter some common arguments deniers use to argue against the science of climate change.

What these few examples show is a general feature of the informal logical fallacies – they are context dependent. Just because you can frame someone’s position as a logical fallacy does not make their argument wrong (thinking this is the case is the fallacy fallacy). What logical fallacy is using details to dismissing the bigger picture? I have heard this referred to as a “Reverse Gish Gallop”. I’m don’t use this term because I don’t think it captures the essence of the fallacy. I have used the term “weaponized pedantry” before and I think that is better.

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Jan 29 2024

Controlling the Narrative with AI

Published by under Technology

There is an ongoing battle in our society to control the narrative, to influence the flow of information, and thereby move the needle on what people think and how they behave. This is nothing new, but the mechanisms for controlling the narrative are evolving as our communication technology evolves. The latest addition to this technology is the large language model AIs.

“The media”, of course, has been a large focus of this competition. On the right there is constant complaints of the “liberal bias” in the media, and on the left there are complaints of the rise of right-wing media which they feel is biased and radicalizing. The culture wars focus mainly on schools, because those schools teach not only facts and knowledge but convey the values of our society. The left views DEI (diversity, equity, and inclusion) initiates as promoting social justice while the right views it as brainwashing the next generation with liberal propaganda. This is an oversimplification, but it is the basic dynamic. Even industry has been targeted by the culture wars – which narratives are specific companies supporting? Is Disney pro-gay? Which companies fly BLM or LGBTQ flags?

But increasingly “the narrative” (the overall cultural conversation) is not being controlled by the media, educational system, or marketing campaigns. It’s being controlled by social media. This is why, when the power of social media started to become apparent, many people panicked. Suddenly it seemed we had seeded control of the narrative to a few tech companies, who had apparently decided that destroying democracy was a price they were prepared to pay for maximizing their clicks. We now live in a world where YouTube algorithms can destroy lives and relationships.

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Jan 12 2024

Big Ring Challenges Cosmological Principle

Published by under Astronomy

University of Central Lancashire (UCLan) PhD student Alexia Lopez, who two years ago discovered a giant arc of galaxy clusters in the distant universe, has now discovered a Big Ring. This (if real) is one of the largest structures in the observable universe at 1.3 billion light years in diameter. The problem is – such a large structure should not be possible based on current cosmological theory. It violates what is known as the Cosmological Principle (CP), the notion that at the largest scales the universe is uniform with evenly distributed matter.

The CP actually has two components. One is called isotropy, which means that if you look in any direction in the universe, the distribution of matter should be the same. The other component is homogeneity, which means that wherever you are in the universe, the distribution of matter should be smooth. Of course, this is only true beyond a certain scale. At small scale, like within a galaxy or even galaxy cluster, matter is not evenly distributed, and it does matter which direction you look. But at some point in scale, isotropy and heterogeneity are the rule. Another way to look at this is – there is an upper limit to the size of any structure in the universe. The Giant Arc and Big Ring are both too big. If the CP is correct, they should not exist. There are also a handful of other giant structures in the universe, so these are not the first to violate the CP.

The Big Ring is just that, a two-dimensional structure in the shape of a near-perfect ring facing Earth (likely not a coincidence but rather the reason it was discoverable from Earth). Alexia Lopez later discovered that the ring is actually a corkscrew shape. The Giant Arc is just that, the arc of a circle. Interestingly, it is in the same region of space and the same distance as the Big Ring, so the two structures exist at the same time and place. This suggests they may be part of an even bigger structure.

How certain are we that these structures are real, and not just a coincidence? Professor Don Pollacco, of the department of physics at the University of Warwick, said the probability of this being a statistical fluke is “vanishingly small”. But still, it seems premature to hang our hat on these observations just yet. I would like to see some replications and attempts at poking holes in Lopez’s conclusions. That is the normal process of science, and it takes time to play out. But so far, it seems like solid work.

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Jan 08 2024

Categorization and What’s In a Name

Categorization is critical in science, but it is also very tricky, often deceptively so. We need to categorize things to help us organize our knowledge, to understand how things work and relate to each other, and to communicate efficiently and precisely. But categorization can also be a hindrance – if we get it wrong, it can bias or constrain our thinking. The problem is that nature rarely cleaves in straight clean lines. Nature is messy and complicated, almost as if it is trying to defy our arrogant attempts at labeling it. Let’s talk a bit about how we categorize things, how it can go wrong, and why it matters.

We can start with an example that might seem like a simple category – what is a planet? Of course, any science nerd knows how contentious the definition of a planet can be, which is why it is a good example. Astronomers first defined them as wandering stars – the points of light that were not fixed but seemed to wonder throughout the sky. There was something different about them. This is often how categories begin – we observe a phenomenon we cannot explain and so the phenomenon is the category. This is very common in medicine. We observe a set of signs and symptoms that seem to cluster together, and we give it a label. But once we had a more evolved idea about the structure of the universe, and we knew that there are stars and stars have lots of stuff orbiting around them, we needed a clean way to divide all that stuff into different categories. One of those categories is “planet”. But how do we define planet in an objective, intuitive, and scientifically useful way?

This is where the concept of “defining characteristic” comes in. A defining characteristic is, “A property held by all members of a class of object that is so distinctive that it is sufficient to determine membership in that class. A property that defines that which possesses it.” But not all categories have a clear defining characteristic, and for many categories a single characteristic will never suffice. Scientists can and do argue about which characteristics to include as defining, which are more important, and how to police the boundaries of that characteristic.

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Dec 21 2023

Science News in 2023

Published by under Skepticism

This is not exactly a “best of” because I don’t know how that applies to science news, but here are what I consider to be the most impactful science news stories of 2023 (or at least the ones that caught by biased attention).

This was a big year for medical breakthroughs. We are seeing technologies that have been in the works for decades come to fruition with specific applications. The FDA recently approved a CRISPR treatment for sickle cell anemia. The UK already approved this treatment for sickle cell and beta thalassemia. This is the first CRISPR-based treatment approval. The technology itself is fascinating – I have been writing about CRISPR since it was developed, it’s a technology for making specific alterations to DNA at a specific target site. It can be used to permanently inactivate a gene, insert a new gene, or reversibly turn a gene off and then on again. Importantly, the technology is faster and cheaper than prior technologies. It is a powerful genetics research tool, and is a boon to genetic engineering. But since the beginning we have also speculated about its potential as a medical intervention, and now we have proof of concept.

The procedure is to take bone-marrow from the patient, then use CRISPR to silence a specific gene that turns off the production of fetal hemoglobin. The altered blood stem cells are then transplanted back into the patient. Both of these diseases, sickle cell and thalassemia, are genetic mutations of adult hemoglobin. The fetal hemoglobin is unaffected. By turning back on the production of fetal hemoglobin, this effectively reduces or even eliminates the negative effects of the mutations. Sickle cell patients do not go into crisis and thalassemia patients do not need constant blood transfusions.

This is an important milestone – we can control the CRISPR technique sufficiently that it is a safe and effective tool for treating genetically based diseases. This does not mean we can now cure all genetic diseases. There is still the challenge of getting the CRISPR to the right cells (using some vector). Bone-marrow based disease is low hanging fruit because we can take the cells to the CRISPR. But still – this is a lot of potential disease targets – anything blood or bone marrow based. Also, any place in the body where we can inject CRISPR into a contained space, like the eye, is an easy target. Other targets will not be as easy, but that technology is advancing as well. This all opens up a new type of medical intervention, through precise genetic alteration. Every future story about this technology will likely refer back to 2023 as the year of the first approved CRISPR treatment.

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Dec 19 2023

An Earth-like Climate is Fragile

Published by under Astronomy

One of the biggest questions of exoplanet astronomy is how many potentially habitable planets are out there in the galaxy. By one estimate the answer is 6 billion Earth-like planets in the Milky Way. But of course we have to set parameters and make estimates, so this number can vary significantly depending on details.

And yet – how many exoplanets have we discovered so far that are “Earth-like”, meaning they are a rocky world orbiting a sun-like star in the habitable zone, not tidally locked to their parent star, with the potential for liquid water on the surface? Zero. Not a single one, out of the over 5,500 exoplanets confirmed so far. This is not a random survey, however, because it is biased by the techniques we use to discover exoplanets, which favor larger worlds and worlds closer to their stars. But still, zero is a pretty disappointing number.

I am old enough to remember when the number of confirmed exoplanets was also zero, and when the first one was discovered in 1995. Basically since then I have been waiting for the first confirmed Earth-like exoplanet. I’m still waiting.

A recent simulation, if correct, may mean there are even fewer Earth-like exoplanets than we think. The study looks at the transition from a planet like Earth to one like Venus, where a runaway greenhouse effect leads to a dry and sterile planet with a surface temperature of hundreds of degrees. The question being explored by this simulation is this – how delicate is the equilibrium we have on Earth? What would it take to tip the Earth into a similar climate as Venus? The answer is – not much.

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Dec 12 2023

Virtual Reality for Mice

Published by under Neuroscience

Scientists have developed virtual reality goggles for mice. Why would they do this? For research. The fact that it’s also adorable is just a side effect.

One type of neuroscience research is to expose mice in a laboratory setting to specific tasks or stimuli while recording their brain activity. You can have an implant, for example, measure brain activity while it runs a maze. However, having the mouse run around an environment puts limits on the kind of real time brain scanning you can do. So researchers have been using VR (virtual reality) for about 15 years to simulate an environment while keeping the mouse in a more controlled setting, allowing for better brain imaging.

However, this setup is also limiting. The VR is really just surrounding wrap-around screens. But it is technically challenging to have overhead screens, because that is where the scanning equipment is, and there are still visual clues that the mouse is in a lab, not the virtual environment. So this is an imperfect setup. k

The solution was to build tiny VR goggles for mice. The mouse does not wear the goggles like a human wears a VR headset. They can’t get them that small yet. Rather, the goggles are mounted, and the mouse is essentially placed inside the goggle while standing on a treadmill. The mouse can therefore run around while remaining stationary on the treadmill, and keep his head in the mounted VR goggles. This has several advantages over existing setups.

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Dec 11 2023

Cultural Blindness

Published by under Skepticism

Not a crow.

One of the core tenets of scientific skepticism is what I call neuropsychological humility – the recognition that while the human brain is a powerful information processing machine, it also has many frailties. One of those frailties is perception – we do not perceive the world in a neutral or objective way. Our perception of the world is constructed from multiple sensory streams processed together and filtered through internal systems that include our memories, expectations, biases, assumptions and (critically) attention. In many ways, we see what we know, what we are looking for, and what we expect to see. Perhaps the most internet-famous example of this is the invisible gorilla, a dramatic example of inattentional blindness.

Far more subtle is what might be called cultural blindness – we can perceive differences that we already know exist or with which we are very familiar, but otherwise may miss differences as a background blur. On my personal intellectual journey, one dramatic example I often refer to is my perception before and after becoming a birder. For most of my life birds were something in the background I paid little attention to. My internal birding map consisted of a few local species and broad groups. I could recognize cardinals, blue jays, crows, pigeons, and mourning doves. Any raptor was a “hawk”. There were ducks and geese, and then there was – everything else. I would probably call any small bird a sparrow, if I thought to call it anything at all. I knew of other birds from nature shows, but they were not part of my world.

The birding learning curve was very steep, and completely changed my perception. What I called “crows” consisted not only of crows but ravens and at least two types of grackle. I can identify the field markings of several hawks and two vultures. I can tell the subtle differences between a downy and hairy woodpecker. At first I had difficulty telling a chickadee from a nuthatch, now the difference is obvious. I can even tell some sparrow species apart. My internal birding map is vastly different, and that affects how I perceive the world.

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Nov 16 2023

Trust in Science

Published by under Culture and Society

How much does the public trust in science and scientists? Well, there’s some good news and some bad news. Let’s start with the bad news – a recent Pew survey finds that trust in scientist has been in decline for the last few years. From its recent peak in 2019, those who answered that science has a mostly positive effect on society decreased from 73% to 57%. Those who say it has a mostly negative effect increased from 3 to 8%. Those who trust in scientists a fair amount or a great deal decreased from 86 to 73%. Those who think that scientific investments are worthwhile remain strong at 78%.

The good news is that these numbers are relatively high compared to other institutions and professions. Science and scientists still remain among the most respected professions, behind the military, teachers, and medical doctors, and way above journalists, clergy, business executives, and lawyers. So overall a majority of Americans feel that science and scientists are trustworthy, valuable, and a worthwhile investment.

But we need to pay attention to early warning signs that this respect may be in jeopardy. If we get to the point that a majority of the public do not feel that investment in research is worthwhile, or that the findings of science can be trusted, that is a recipe for disaster. In the modern world, such a society is likely not sustainable, certainly not as a stable democracy and economic leader. It’s worthwhile, therefore, to dig deeper on what might be behind the recent dip in numbers.

It’s worth pointing out some caveats. Surveys are always tricky, and the results depend heavily on how questions are asked. For example, if you ask people if they trust “doctors” in the abstract the number is typically lower than if you ask them if they trust their doctor. People tend to separate their personal experience from what they think is going on generally in society, and are perhaps too willing to dismiss their own evidence as “exceptions”. If they were favoring data over personal anecdote, that would be fine. But they are often favoring rumor, fearmongering, and sensationalism. Surveys like this, therefore, often reflect the public mood, rather than deeply held beliefs.

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