Stephen J Gould (still my favorite science essayist) wrote an excellent article in 1985 (Red Wings in the Sunset, later published in his book, Bully for Brontosaurus) about artist and naturalist Abbott Handerson Thayer. Thayer wrote about how animals use coloration as camouflage – what he called “cryptic coloration”. His ideas were solid, but he made a classic mistake that scientists sometimes make, overapplying their key discovery. Thayer argued that all animal coloration is cryptic. For example, he argued that flamingos are pink because it hides them in the setting sun (hence the title of the essay). This is a transparently absurd argument, and it shows how Thayer tried to shoehorn all evidence into his preferred and absolute narrative. It is better to assume that nature is complex, and all explanations are at best partial (unless proven otherwise). Animal coloration, in fact, can serve many different purposes, only one of which is camouflage. Thayer also struggled with the male peacock, for example. Butterflies appear to be another example. Actually, many butterflies are camouflaged on the underside of their wings, so that when they are at rest with their wings up they tend to blend into their surroundings. But the top side of their wings are often very colorful and not camouflaged at all. One assumption is that the brightly colored part of their wings is to attract mates. This may be true, but that does not mean the coloration does not serve another function. Often animals use visual cues when choosing their mates that are markers for health and success. As evidence that butterfly wing color may be serving a survival benefit, if you look at birds that feed on insects during flight, they target dully-colored moths much more than brightly colored butterflies, even though the butterflies should be easier to see. A recent study tests the hypothesis that the brightly colored and patterned top side of butterfly wings may have evolved to produce an optical illusion to confuse predators. The idea of using optical illusions as visual protection in animals is not new. For example, zebra stripes allow zebras to hide in the herd, confusing predators as to where one zebra ends and another begins. Stripes on zebras and snakes may also serve to confuses predators about their direction of motion, but this hypothesis has not been tested previously. The researchers started by filming butterflies taking off using high speed cameras. They found that the wing patterns created a powerful “barber pole” illusion. The stripes on a barber pole look like they are moving up or town even when the pole is just spinning. Similarly, the wing patterns combined with the way butterflies move their wings and their flight dynamics combine to create a similar barber pole illusion, making the butterfly look like it is moving down when it is in fact moving up. They also showed that this strategy is phylogenetically widespread. They then did modeling in silico and showed digital creatures converge on butterfly-like patterns. To understand how effective this strategy can be it’s important to understand how catching a butterfly in midflight works. Butterflies have a very jumpy pattern of flight. In order to grab them in flight, a bird will have to zero in on their exact location with a few hundred millisecond and millimeter precision. If the butterfly suddenly zigs while the bird perceives that they zagged, the birdy will miss. Alternatively they may make only a glancing blow or grab an edge of a wing rather than their body. Either way, the butterfly lives another day and the bird goes hungry. In zebras this effect has been referred to as the “visual dazzle” strategy. Now there is some empiric evidence that this works not just by confusing predators, but by creating a specific optical illusion. Zebras will also zig-zag to evade predators, and misjudging that last second movement can cause a pouncing lioness to miss. There are two specific illusion effects at work – the aperture effect and spatiotemporal aliasing. The aperture effect refers to the brain’s processing of visual information through a limited field of view. The visual system has a hard time processing many moving stripes, and specifically will confuse the direction of movement (this is the barber pole effect). So a predator may miss a zebra’s vertical movement, for example, and perceive all movement as perpendicular to the stripes. They may also misinterpret the angle of movement and only perceive the perpendicular motion. Spatiotemporal aliasing has to do with ratio of the movement with the “refresh” speed of the brain’s visual processing. You have likely seen this with spinning wheels that have spoke-like features. As the wheel slows down, at one point the spinning will appear to stop completely, and then will appear to spin backwards. This is simply an artifact of your brain’s visual processing speed. Now imagine being surrounded by a field of rapidly moving and zig-zagging stripes, and your brain trying to make sense of all this information, while trying to compensate for these powerful optical illusions. Butterflies don’t have a herd to hide in, but they do have the added element of their flapping wings. Not only are they moving in a way to maximize these optical illusions, their wings are also doing this, while alternating top-side and bottom-side. Some butterflies have bright spots on their colorful upper wings, that will flash as they flap their wings, causing another type of dazzling disorientation. I will end by returning to my original point – do not be limited in the types of explanations that you reach for when trying to understand nature. Nature is not so limited. Animals do not just use coloration for camouflage and attracting mates. They can also use their coloring for thermoregulation, for mimicking other animals, for producing a danger-signal to would-be predators, and to communicate with other members of their species. It can communicate mood, danger, or social status. Now we have to add optical illusions to the list. There may be other strategies yet to be discovered or imagined. The post Butterflies Are Masters of Illusion first appeared on NeuroLogica Blog.

Solar power as a source of electricity has been on a meteoric rise, and has crossed some encouraging milestone recently. Every way you look at it, solar is booming. This is driven primarily by the decrease in the cost of adding solar power, so let’s start there. The Berkley Lab has been tracking the cost of solar power in the US for years, so they are a reliable source of information. They get direct data from the actual price paid by consumers, and break down the cost of panels, the cost of installation, and all the “soft” costs that  are part of the industry. In 2009 the total cost of installing solar between $7 – 8.70 per watt. An average US residential home installs a 6-8 kW system, with the average increasing over the years. In 2025 the average size was 7.7 kW. Let’s use a 7 kW system, at $8 per watt, that’s $56,000 total installation cost. Today the average price of installed residential solar in the US is $3.6 per watt (but it is $3.0 if you pay upfront, $4.50 if you finance). So that same 7 kW system now costs $25,200. (If you pay for it outright, the cost drops to $21,000.) So over the last two decades the total const of installed residential solar has dropped by about 60%. This is without considering any tax breaks or incentives. The reason for the decrease is partly that solar panels themselves are cheaper, and they are more efficient, so a 7kW system requires fewer panels. Installation costs have decreased by about 50% over this time, largely due to economies of scale. However, the US still has higher soft costs for solar than many other industrialized nations, and this is mostly a matter of the regulatory system. So there is some regulatory efficiency to be gained. Solar companies themselves also have some possible efficiency gains. Fortunately, the net price for solar continues to go down, with another 50-60% decrease in total price possible even without further technology gains. Commercial and grid scale solar is even cheaper – with large non-residential installations down to $2.4 per watt. It is primarily for this reason that solar is now the most common new source of added grid capacity. Worldwide, wind and solar are responsible for 85% of new grid capacity, with solar making up 73%. Worldwide there is now about 3 TW of installed solar capacity. One TW was added in just the last two years, showing the exponential increase in solar installations. Solar now generates 9-10% of the world’s electricity. This is led mostly by China, which as 50% of the world’s installed solar. For a long time, while wind and solar were increasing rapidly, they were more than offset by the total increase in electricity demand. This is still much better than not installing renewable or low-carbon energy, but it meant that fossil fuel use was still increasing. For the first time, however, total electricity from fossil fuels decreased, by 0.2%, without being caused by an economic downturn (like COVID). This is a tiny decrease, but it is a potential milestone if we have truly turned a corner. Even better, this decrease is driven primarily by coal, which is the dirtiest form of energy. Natural gas plants are still increasing, because they are still necessary for peaker plants, and because of the increased demand of data centers. The rise of solar is helping push down demand for fossil fuel energy, but there are two other factors that will be critical to push them down further. The first is grid battery storage. Battery technology is also improving rapidly. The advent of cheaper sodium ion batteries (which also bypass the lithium bottleneck) is seeing battery grid storage rise considerably. More and more of those home solar installations include battery back up. There are also new innovations, such as plug and play home battery backup, where you can add storage capacity in a modular fashion without any installation costs – just plug them in. Regulations need to catch up to this technology, allowing them to be used for whole home backup, but for now they can be used for targeted backup, like for your refrigerator, or your work station. Grid storage has the capability of reducing reliance on natural gas plants. So does nuclear. We seem to be at the beginning of a revival of the nuclear power industry. This is necessary even if we wish to simply maintain the current percentage of nuclear on the grid, which will help keep fossil fuel use down. The bottom line is that the cost of solar has dropped precipitously, and so if you have not looked into it recently, you should take another look. The prices I gave above were for a fairly large home. The total price of the system scales with the size of the house, which is a marker for the financial resources of the owner. Let’s say you have a more modest house that only needs a 5 kW system. If you pay for it outright, the total cost would be $15,000. The federal tax incentive just ended on Jan. 1, 2026, which is unfortunate but is defensible due to the fact that the cost of solar has dropped so much. However, 30 states still have some incentive, which can save thousands of dollars. But that aside – $15,000 is very affordable. How much this would save depends on a lot of variables, but for an average home in the US it would be between $800 and $1,500 per year. That means the payback time is between 10 and 18 years. After that, you essentially have free electricity. The useful life expectancy of a new system is 25-30 years, roughly double the payback time. Most solar companies now bundle solar installation with batter backup systems. This allows for peak shaving, and backup during outages. There is potential money savings here as well (including every time you don’t loose a freezer full of food). Further, many states offer incentives for batteries as well, if you allow them to use your batteries for grid storage. A battery system can also keep your solar panels functioning during a power outage. The trend lines for solar and battery grid storage are pretty dramatic and there is every reason to predict that they will continue, as further incremental technology advances take place and economies of scale kick in. The post Solar Is Booming first appeared on NeuroLogica Blog.

I am back from an almost three week trip to LA, Sydney and Christchurch. Sorry I did not have time to keep up with my blog over that period – in which we recorded four live SGU shows, produced three days of conference content, put on two stage shows, and hosted several other events. It was a tremendous amount of fun, but also a great deal of work. I am now jet-lagged and fighting off the remains of a viral infection I picked up along the way. Such trips always reinvigorate my dedication to science communication and scientific skepticism. I appreciate every conference-goer who came up to tell me about their personal journey and the role the content I have helped produce had played in it. I thought I would share some further observations from the trip. First, while the skeptical movement, such as it is, has been through a lot, it is still alive and well. The crowds we are able to attract to these events remain robust, and in fact are larger than many past events. There is a lot of enthusiasm for science and critical thinking. There is also a deep hunger for developing the skills to navigate our increasingly complex world. How do we deal with what social media, growing misinformation, deep fakes, and now artificial intelligence has wrought? People also have a deep desire for community – the kind of community that comes from getting physically together for a shared purpose, not just online.  The number of people we can reach in these physical conferences and meetings is much smaller than online, but I think it remains a critical complement to online content. It also reinforces what I think many of use have learned from the “social media” phenomenon. Online communities are not the same as in-person communities, just online. People interact differently in person and online. The dynamics of social media were simply not what many of us expected. I don’t think we should abandon social media (although I know people who make a reasonable argument that we should), but rather we need to have a more realistic view of its strengths and weaknesses, its vulnerabilities and psychological effects.  The conference goers were pretty similar, demographically, to what they have been over the past 30 years, which means there seems to be a steady state of younger skeptics entering the movement. There are more women than in the past, but still very few people of color – a social nut we have yet to crack. The issues about which people are interested are dramatically different than in the past. At a similar conference in the 90s or even oughts, there would be many questions about Bigfoot, UFOs, astrology, snake oil, and similar pseudoscience. Today people are interested in science denial, misinformation, AI, the trans debate, and similar societal issues (although snake oil is still prominent, perhaps more so). This is also the first big international trip I have taken since COVID and Trump 2.0. People in Australia and New Zealand had similar reactions, it seems. They still consider the US an ally, but they are deeply saddened, frightened, and perplexed by US politics. The first Trump administration could be dismissed as a fluke. The second, they reasoned, is evidence of something deeply wrong with American politics, something that might endure past Trump. This means that the US is no longer a reliable partner, and they must hedge their bets. They need more independence and need to carefully calibrate their relationship with China. There was also a strong consensus that this change is permanent – we will never fully recover our place in the world post-Trump. Interacting with people outside the conference was also interesting. Many people were still friendly, but some were cold or even passively hostile when learning we were Americans. It was nothing we couldn’t overcome with a bit of humor, but it was still disconcerting. It was also interesting being away from American media for three weeks. New Zealanders are chill, what a local New Zealand political scientist described to me as “low voltage”. Everything seems to be working fine and their politics are fairly low stakes. Australians are a more rowdy bunch, but still pretty low drama. It was just refreshing being away from the constant culture wars and American media stoking outrage and controversy at every turn. It really brought home how toxic American politics has become. But now I’m back. I guess I have to start looking at American news again. Perhaps I’ll wait until my cold is over. The post Back From Down Under first appeared on NeuroLogica Blog.

I often get questions like the one below: “I live part time in Japan. Everyone sees hydrogen powered generators, trains, trucks, etc regularly. High density population means it’s easy to get enough synergy to justify the infrastructure. So sad we aren’t doing more to utilize this great tech. Hydrogen combustion engines emerge as cheap alternative to fuel cells.” https://asia.nikkei.com/business/energy/hydrogen-combustion-engines-emerge-as-cheap-alternative-to-fuel-cells This is often how news about advances in hydrogen tech are framed. The problem is – the limitations with hydrogen technology have nothing to do with the tech itself, so tech advances are mostly irrelevant. Also, hydrogen combustion is not a better solution for most use cases then hydrogen fuel cells. Fuel cells use an electrochemical process to combine hydrogen and oxygen, producing electricity and water. They are about 60% efficient, produce no pollution, and have no moving parts. Hydrogen combustion operates more like a regular engine, but with hydrogen as the fuel. They are about 40% efficient, produce nitrogen oxides as pollution, and have moving parts that operate at high pressure and temperature. They can be, however, more powerful for heavy applications and are cheaper to build. For cars hydrogen combustion is a terrible idea. Maybe there is a use case for large generators, trains, and heavy trucks. Even there, however, there are current limitations that the technology of hydrogen engines or fuel cells do not address. 1 – Storage is a problem. They never figured out the storage problem, so just reverted to compressed hydrogen gas. There are efficiency, range, and safety issues with this. Plus, hydrogen is very leaky and destructive to infrastructure like pipes. 2 – Only about 1% of the world’s hydrogen production is green. Most of the rest is gray – essentially stripped from hydrocarbons. This is actually worse then just burning the hydrocarbons for fuel. If we do manage to ramp up green hydrogen production, it should be used first in industry, like steel production. Massive green hydrogen for transportation is a long way off. 3 – Even if we solve 1 and 2, hydrogen cars are less efficient than battery EV, and always will be (60% vs 80% efficient). This is just physics. Further, battery tech has simply advanced more quickly than hydrogen, and it continues to advance. Hydrogen lost this technology race. We may be able to fix the first issue with new materials, but until we do this is a major limitation. This is the main reason that the “coming hydrogen economy” promised back in the early 2000s never happened. There are three promising ways we may solve the second issue. The first is scalable green hydrogen production. If we had solar arrays or wind farms generating electricity to electrolyze water into hydrogen and oxygen, that could produce green hydrogen. The problem here is – we would be better off using that green energy for electricity. Round trip energy efficiency (electricity to hydrogen back to electricity) is only 30-40%. Better to use the electricity directly. Until we have decarbonized the energy infrastructure, don’t use green energy to make hydrogen for light transportation. Where there may be reasonable use is for hydrogen for heat-intensive industries, like steel, and for heavy vehicles like trains and ships. The second possible solution is if there turns out to be vast reservoirs of hydrogen under the ground we can tap into (so-called gold or white hydrogen). This remains to be seen, however. A third potential source is as a byproduct of nuclear reactors. Any reactor can make some hydrogen by radiolysis – splitting water by radiation. High temperature reactors can also make hydrogen through thermal methods. And any reactor can use their electricity for electrolysis, but this has the same issue as using renewable power. The third issue I think is just inherent to these processes. Battery EVs are likely to be always more efficient than hydrogen fuel cells. There may have been a window 20-30 years ago where hydrogen fuel cells could have leap-frogged BEV’s, but that window is now closed. Battery technology won, and also continues to steadily improve. Even if we make progress in hydrogen fuel cells or hydrogen combustion, we still have a hydrogen storage and transportation bottleneck. There have been advances here as well, but they come at a cost. Liquid Organic Hydrogen Carriers (LOHCs) can bind hydrogen to a fluid for easy storage and transportation, then heat the fluid to release the hydrogen. However, this has massive infrastructure and energy requirements, and would further reduce the energy efficiency of hydrogen. We have also engineered better storage tanks – Type IV tanks, which feature a seamless polymer liner fully wrapped in high-strength carbon fiber. This doubles the pressure under which hydrogen can be stored, doubling the range of hydrogen fuel cells. But it takes 12-15% of the energy stored in the hydrogen to compress it to these higher pressures. A hydrogen economy for transportation would have massive infrastructure needs, from production to pipelines, storage, and distribution, likely to take decades. This is all just to get us to a system that is less efficient than BEVs with similar range. Meanwhile there is already existing battery technology with twice the range of common BEVs today (silicone anode Li ion), or similar range at half the cost (Na ion). Solid state and lithium air batteries could potentially five times or more today’s energy density (1,500 vs 300 kWh). Meanwhile we are already near the theoretical limit of compressing hydrogen (700 bar). At 1000 bar hydrogen atoms repel each other and you get exponential energy requirements for further compression. If we are going to invest in infrastructure, those investments should go to fleshing out a fast-charging network for EVs and securing raw materials for making batteries. The post Hydrogen Tech first appeared on NeuroLogica Blog.

In Isaac Asimov’s The Caves of Steel he imagines a future in which most of humanity lives in gigantic cities, extending many levels underground. This leaves the majority of the Earth’s surface for industrial farming, necessary to feed all those densely populated cities. If you take a similar strategy, however, and keep the population at sustainable numbers, this could maximize land for natural ecosystems and also minimize the environmental footprint of the average person. So if we are going to plan our civilization around environmental sustainability we would not necessarily need Asimovian megacities, but we could concentrate the population in cities and in densely developed areas around cities, and leave large stretches of land in between undeveloped. This is far better than endless suburban sprawl. But of course, we are not starting from scratch, and our current layout was not planned by some central committee but evolved organically. Pragmatically, the question we need to ask is – where do we go from here. Cities are growing dynamic things, so we can use city development to move in a certain desirable direction, even if we can’t tear it all down and start anew. This means it is important to study what the best city planning and development would be going forward. When most people think of city planning to reduce the carbon emissions of transportation, the first thing that comes to mind is planning city centers so that they are walkable/bikeable and to provide public transportation, in order to minimize reliance on fossil-fuel burning cars. This also has the advantage of reducing city traffic, which can be a nightmare. However, a recent study suggests that, while important, this may be of secondary concern with respect to impact on CO2 emissions. For many cities, especially those with a single concentrated hub (as opposed to multicentric cities, like LA), the most impactful strategy might be the densification of a ring surrounding the city center. The range of this ring depends on the city, but is something like 10-20 km for a typical large city, but can extend to 40 km. Increased density can be accomplished with infill development, as many such zones are only moderately developed leaving lots of room for densification. The idea is that the workplaces will be concentrated in the city center, and the workers will live in the ring around the city center, minimizing their commute distance. This could have a significant impact on the average commute distance that people have and therefore their transportation carbon footprint. This approach would work better for some cities than others, depending on geography. This plan could also maximize the impact of public transport, like buses and trains, dedicated to bringing people back and forth from this densified ring to the city center. One of the major findings of the study, which used gps data to track 10 million “mobility data points”, is that there are many interdependent variables at work. It is not as simple as just densifying a certain distance from a city center. Road planning, public transportation, carpooling, and working from home are also important variables that affect each other. Essentially, what this study does is provide additional information to city planners, using an AI model to help individual planning to each city in order to minimize average commute distance. The authors acknowledge that there is still a lot of research to do in this area. The one variable that is always the most difficult to predict is human behavior. For example, we cannot simply build more roads to accommodate increased traffic, because more roads creates “induced demand” and may actually worsen traffic. In this case we need to deal with the fact that many people move out into the suburbs, increasing their commute, because they want to. It’s nice there. At the same time there is a “build it and they will come” phenomenon – people will buy or rent houses that exist. Since we are having a housing shortage, we have an opportunity to decide where to build the millions of homes we need to meet demands. Generally speaking, however, it is a good idea not to assume that people will do what you want them to do, and to provide multiple options for different people with different desires and in different situations. At the same time, when dealing with these big environmental issues, it is not necessary for every single person to do the same thing. We just need to move some people toward behavior associated with lower emissions, by making certain choices more desirable or easier. The effects of behavior and infrastructure on CO2 emissions are cumulative – in both directions, good and bad. I also think generally we should not expect most people to make big sacrifices to achieve our collective goals, not for moral reasons but for practical reasons. But I also think we should not always put the burden on the individual to make the sacrifice. It’s better to look for the win-wins, to make the system work for people rather than making people work for the system, and to provide the infrastructure and opportunity for people to make choices that are good for them and good collectively, in this case for the environment. With all that in mind, what would I like to see in terms of minimizing the carbon footprint of transportation? First, I would love more walkable cities with less traffic, and with convenient low-cost transportation options. More convenient and cost effect transportation options into city centers would also be nice. Where I live the best option I have is to drive to the nearest train station and then pay ridiculous prices for a train ticket. If the family is taking a day-trip to the city, it could literally cost hundreds of dollars. Also, as this study indicates, careful city planning to minimize commute distance could have a significant impact. There is a confluence of issues here. In the US we lack overall housing, we also lack mid-level housing in terms of costs.  We need more condos, row houses, and multi-family units – something between an apartment and a large house sitting on a half-acre. These are exactly the kinds of homes that could be built to densify key regions around city centers. We could essentially address three problems at once. Meanwhile, we need to continue to convert from fossil fuel burning to electric vehicles. These are more energy efficient and have a much lower carbon footprint over their lifetime. They are also now cheaper to own and have much less maintenance. Having shorter average commute distances would also make EVs, even those with modest ranges, more convenient. We are already past the technological tipping point in terms of the features of EVs themselves. The big issue is that we need to continue to build out the EV public charging infrastructure. They need to be ubiquitous. I also think that we need to make a big push for working from home. This happened during COVID and I was hoping that everyone would realize the benefits and the trend would continue. However, once the pandemic was over some businesses snapped back to their old policies, and mostly with no good reason. We did make good progress, but not as much as we should have. We should be doing everything we can to maximize working from home. If the average worker worked from home 2 days a week, that would reduce commuting by 40%. This massively reduces traffic and CO2 emissions. Increasingly many people’s jobs involve lots of time sitting in front of a computer. There is no reason for them to commute to an office to do that. Schedule meetings on one or two days a week. In fact, in my experience, many work places have too many meetings. Most of what needs to be accomplished can happen in virtual time, then you can have one meeting to review everything. Obviously this has to be individualized to the workplace, but there are many businesses where there are lots of opportunities to reorganize workflow so that many people can work from home much of the time. Further – working from home increases productivity. The same is true of the 4 day work week – it maintains or increases productivity. This is because of the same principle I discussed above – people are not machines that will just do what you tell them (short of oppressive environments). People work more efficiently when they are in a better mood, and have a better work-life balance. Most of these things are win-wins. People do not want to spend large amounts of their life stuck in traffic, sitting in a car that is spewing out pollution. So give them other options, make commutes shorter, let people work fewer days and many days (or all days) from home. Provide cheap public transportation. And when they do have to drive, EVs are a superior option for many people, and we should do what we can to make it the best option for as many people as possible. The post City Planning and CO2 Emissions first appeared on NeuroLogica Blog.