It’s hard to keep up with all the latest science and technology, even for an enthusiast. Entire new fields are emerging, and it can be challenging for the non-expert to wrap their head around all the new concepts. Here is my attempt to quickly tackle a relatively new idea in physics – twistronics.

The term refers to tuning the properties of 2-dimensional materials by stacking them and rotating the layers with respect to each other. This is a lot harder than it sounds – graphene (2d carbon in a hexagonal configuration, like chicken wire) for example likes to align itself and will resist such twisting. Further, it is difficult to make pure 2d sheets without errors or contamination. But some theoretical physicists were predicting that interesting things might happen at certain “magic” angles of rotation, such a 1.1 degrees. It was then left to experimental physicists to make it happen.

This has all been happening very quickly, over the last few years. It was in 2018, in fact, that physicist Pablo Jarillo-Herrero published the first study showing the properties of graphene “devices” with a twist angle of 1.1 degrees. What he found at this magic angle was something, he now reports, that he dared not predict or even hope for, one of the holy grails of material science – superconductivity.

A superconducting material is essentially one that allows for the flow of electrons without any resistance, and therefore no loss of energy as heat. Superconductivity would transform our electrified world and allow for the creation of much more powerful and efficient electronics. Physicists have created a number of superconducting materials, but at low temperature. The trick is to make so-called high-temperature superconducting material. This first became a popular sensation in the 1980s, with the discovery of superconducting ceramics. At the time, if you believed they hype, it seemed like a matter of just years before we would have room-temperature superconductors, with devices sitting on every desktop. Reality proved much more difficult.

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In the last 20 years I have been called to jury duty several times. Every time I was dismissed almost instantly, once I made it known that I am a professional skeptic. Apparently lawyers fear that kind of skepticism on their juries (at least one side always did). The same is true of many of my skeptical colleagues, so I am not an isolated case. Once my brother said during the process that he wrote an article on the fallibility of human memory and eyewitness testimony. His but barely hit the seat when he was dismissed.

It is unclear how best to interpret these anecdotes, but what is clear is that justice requires facts and needs to align optimally with reality. Falsehoods and pseudoscience do not generally lead to justice. It is for this reason that courtrooms have elaborate rules of evidence, and generally they work well. Even in our adversarial system, you need to use generally valid arguments, you need to back up your statements with evidence, and there are rules of admissibility. Each side provides a check on the other, as a neutral arbiter presides over the process. It is imperfect (because imperfect people are involved) but at least it has a process.

One area where this process has historically had significant problems, however, is in forensic science, and the admissibility of science itself. The main problem, as I see it, is that it is based largely on authority, in both a good and bad way. Each side is allowed to find their own experts, and they can cherry pick experts whose opinion aligns with their needs. Often a non-expert jury is then tasked with sorting it out. There are standards for which expert testimony is admissible, and this has been a controversy unto itself. Here is a good summary:

Prior to 1993, the Frye standard for admitting expert testimony was the prevailing standard for guiding federal and state courts in their consideration as to whether scientific expert testimony should be admitted at trial. Frye v. United States[1]. The Frye standard requires that the proponent of the evidence establish the general acceptance of the underlying scientific principle and the testing procedures. Notably, Frye only applies to new or novel scientific evidence. However, in 1993, following a revision to the Federal Evidence Code by Congress, the Supreme Court of the United States annunciated the new standard in Daubert v. Merrell Dow Pharmaceuticals, Inc.[2] The Daubert inquiry was meant to be flexible and focused on scientific principles and methodology, not conclusions. The Daubert opinion emphasized that the Federal Rules of Evidence governed admissibility and suggested a series of factors a court could consider, but did not establish a test per se. Under Daubert, the admissibility of expert evidence rests squarely within the discretion of the trial court judge. In contrast to Frye, Daubert applies to all expert witness testimony.

This article is about the fact that Florida has reverted to the Frye standard recently. This highlights the fact that legal precedent is largely how this is sorted out, and may differ for every state and at the federal level.

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Here is a tiny bit of good news on the climate change front: A new analysis finds that there is more than enough storage space globally to fit the carbon we would need to capture and store if we wish to meet our climate change goals. The found:

No more than 2700 Gt of storage resource is required under any scenario to meet the most ambitious climate change mitigation targets.

Meanwhile current estimates of global carbon storage capacity are around 10,000 Gt. This does not mean we will meet our targets, it only means that global carbon storage capacity will not be a limiting factor. It’s always fun to learn that something you didn’t even know was a problem turns out not to be a problem anyway. But let’s break this down a bit.

The study modeled climate change mitigation scenarios using different assumptions about reducing fossil fuel use, increasing renewable energy, electrifying the transportation sector, energy efficiency, and carbon capture. They ran 1,200 different scenarios through the simulation, and found that under any scenario the maximum amount of carbon storage that would be necessary to meet the goal of no more than 2 C warming is 2,700 Gt. How much storage we would actually need, however, varied considerably based upon the other details. Specifically, the faster we ramp up carbon capture and storage (CCS) the less storage space we will ultimately need. The longer we wait, the harder it will be, and the more we will need to make up for lost time with CCS.

Also, like many resources, space for CCS varies in terms of convenience and cost. The more space we need, the more we will have to rely upon the less and less efficient storage space. So the longer we delay climate mitigation, the harder it will get.

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Perhaps one of the positive outcomes of the pandemic is an acceleration of acceptance of telehealth and telementalhealth – treating patients online instead of in person. For example, we have been trying to institute telehealth where I work for years, but have met with roadblocks. Then, all of a sudden, we were able to do it. Our clinic manager estimates that we accomplished in three weeks what would have otherwise taken three years. I have been doing mostly telehealth visits for the last two months now. It’s not perfect, but for many patients it is an ideal option.

The advantages are pretty obvious. A regular visit involves driving into a clinic (which may be in a city, and involves fighting traffic and finding parking), then checking in, and sitting in the waiting room until finally called. Then the meeting happens with the physician. Afterwards you go to check out, and then have to drive home. Depending on the length of the drive, you may spend 2 hours or more total time for 10 minutes of face time with the physician for an uncomplicated follow up visit. Compare this to signing onto an app from the comfort and convenience of your home, having the 10 minute visit over video, then you are done. This also means you are not sitting in a waiting room with potentially sick individuals. Many patients also have a difficult time getting to the clinic. They have physical limitations, and may even require special transportation to get there.

You can even do a limited physical exam over video. Anything that is purely visual and doesn’t require physical contact can be examined. But many patients do not require a physical exam as part of their follow up – their original exam was normal and there is nothing to follow. I see many patients with migraines, for example. Once it has been established that their headaches are indeed migraines (the workup, including exam, for other causes is negative) there is no need for any further physical exam unless something changes. Continue Reading »

Amid the current crisis there is some good news and significant progress – America is returning to crewed spaceflight after a 9 year gap. Scheduled for May 27th is the first crewed mission of the Space X Dragon capsule, which will send two astronauts to the ISS,  Bob Behnken and Doug Hurley. Technically this is the last test flight of the Crew Dragon capsule (the mission is called Demo-2). Last March the Demo-1 mission sent an uncrewed Dragon capsule to the ISS. The two astronauts will remain for an “extended” stay on the ISS, and then return in the capsule, splashing down in the Atlantic and recovered by a Space X recovery vessel.

If successful this will mark the return of America’s ability to send astronauts into orbit. It will also mark the first time a commercial company has done so, and is a significant milestone in the commercialization of space flight. The launch will be done in cooperation with NASA, lifting off from Pad 39A, which is the same one that launched Apollo and the Space Shuttle. The capsule will also be lifted to the ISS by a Falcon 9 rocket, which is also made by Space X. This is the rocket that can land again vertically and be reused.

There has been some back and forth on whether or not the Crew Dragon capsules themselves can be reused. Initially Musk predicted that the capsule could be reused many times, reducing the cost of getting astronauts into space. Then in 2018 they quietly backed away from this goal. The reason is that after a salt-water landing, it is time consuming (a year) and expensive to service the capsule for reuse. In order for capsule reuse to be practical you need a dry landing, which was the original plan of Space X. Apparently that has proven technologically difficult, so Space X is settling for salt-water landings, which means no reuse. However, the Crew Dragon capsule can more easily be refurbished and reused for Cargo Dragon missions without astronauts. Therefore, they will be used for this purpose. Space X has reused multiple Cargo Dragon capsules multiple time.

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Here is yet another incremental advance in brain-machine interface (BMI) technology – decoding what someone is saying from their brainwaves using a neural network and machine learning. We are still a distance away from using a system like this to allow someone who cannot speak to communicate, but the study nicely illustrates where the technology is. Here is the BBC’s reporting:

Scientists have taken a step forward in their ability to decode what a person is saying just by looking at their brainwaves when they speak.

They trained algorithms to transfer the brain patterns into sentences in real-time and with word error rates as low as 3%.

Previously, these so-called “brain-machine interfaces” have had limited success in decoding neural activity.

Now here are all the caveats from the paper. First, the technology used electrocorticography (ECoG), which is an EEG with brain surface electrodes. So this requires an invasive procedure, and persistent electrodes inside the skull and on top of brain tissue. Also, in order to get the best performance, they used a lot of electrodes – resulting in 256 channels (a channel is a comparison in the electrical activity between two electrodes). They simulated what would happen with fewer electrodes by eliminating many of the channels in the data, down to 64, and found that the error rates were about four times greater. The authors argue this is “still within the usable range” but they consider usable range up to a 20-25% error rate. What this shows is that – yes, more electrodes matter. You need the very fine discrimination of brain activity in order to get good (usable) results.

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This is an interesting idea that will probably not be actually implemented (although not impossible) but does raise some important points. A paper explores the viability of using urea from human urine as an agent in lunar concrete. Why is something like this even being considered?

The overwhelmingly dominant factor of building anything on the Moon is that it costs about $10,000 to put one pound of anything into Earth orbit, and more to take it to the Moon (although most of the energy would be used just getting into orbit). This is why it is a high priority for NASA to reduce the cost of getting stuff into space. Elon Musk has also made this a priority and SpaceX is geared mainly toward this purpose. Even if they reach their goal of reducing the cost by 10 fold, to about $1000 per pound, that still adds up when you are trying to build an entire Moon base. One solution is to use as much native material as possible.

Let’s talk a bit about the lunar regolith. The term regolith just refers to any loose material on top of the rocks on a world’s surface. The Earth has regolith, we call it dirt, sand, or soil. The lunar regolith is the result of micrometeors pulverizing the lunar surface for billions of years. In most locations the regolith extends down 4-5 meters, but can be as deep as 15 meters in places. Because of the absence of natural erosion from wind, water, or biological activity, the lunar regolith remains sharp and pointy. So the Moon is basically covered with a deep blanket of fine but jagged dust.

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One extremely exciting technology that is in development is the brain-machine interface (BMI). This technology allows for communication between a biological brain and a computer chip. Once perfected, the implications are incredible. Perhaps most exciting is the possibility of  robotic prosthetics that can be controlled with the mind. There are many medical conditions that impair the ability to move, from spinal cord injury to strokes that can literally cause people to be “locked in”. In many conditions the brain is working, but the peripheral nervous system is damaged. With a sufficiently functioning BMI non-functioning limbs or blockages in communication can be bypassed. Amputees could also have fully robotic limbs to replace what’s missing.

From a theoretical perspective, all of the necessary proofs of concept have been done. The brain can learn to control machines, even computers. The brain can map itself to new limbs, and it can incorporate new sensory feedback. With sufficient sensory feedback, control is enhanced, and the sensation that the new artificial limb is part of one’s body can be complete. We can even be made to feel as if we occupy virtual avatars.

Computer hardware and software technology are already powerful enough meet the demands of any such BMI application. Robotics are also functional enough to work, although there is certainly a lot of room for improvement here. All these components are good enough to use right now, and continued incremental advances will just make them better.

The main limiting factor for BMI applications right now is the interface itself – how do we connect the brain to silicon? Scalp surface electrodes are the safest and most convenient. Electrical signals from the brain do make their way through the skull and scalp and can be recorded, but they are greatly attenuated. Only relatively large parts of the brain firing at the same time produce a sufficient signal to produce a detectable wave at the surface. Still, even with this method there are BMI applications, but the discrimination is limited.

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We have many current solutions to the energy challenges we face – solar, wind, geothermal, hydroelectric, nuclear. I and others have previously argued that if we are going to have the best chance to minimize climate change as much as possible, we need every option on the table. That is partly because no one of them is perfect, and they get worse the more you try to push penetration into the energy infrastructure. So best to pick the low-hanging fruit from each. Also, if we try to solve our energy problems with one solution we would likely run into shortages of raw material and optimal locations.

In fact, it would be nice to add more options. Researchers are aggressively trying to work out the challenge of fusion energy, for example. Even if that succeeds it won’t be the one optimal solution for all our energy needs, but it will help a lot. We also need better grid storage options. You may also notice that I did not have biofuels on the list, because I think it’s unlikely they will make a major contribution, at least not if they need to use up arable land that could be used for food production. But if we can develop a biofuel process that does not require premium arable land, that could fill a niche also.

There is another possible technology on the horizon that occasionally grabs headlines when some incremental advance is made – the artificial leaf. This term is used to refer to any process that uses light in a photosynthesis type process. So it is not a photovoltaic, directly creating electricity, but rather is using light to split water and combining the hydrogen with CO2 from the atmosphere to make fuel. Essentially, this is artificial biofuel. Then why not just use biological leaves to make biofuel? That gets back to the land issue – you could theoretically have a biofuel plant using an artificial leaf process in the desert. I suppose theoretically you could also use salt water for the process, and would therefore not be a drain on our fresh water supply (but I am not sure about this).

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I’m a sucker for perpetual motion machines. I don’t mean that I think they work – they don’t – but they are often intriguing contraptions out of some cyberpunk fantasy. They are also often a bit of a puzzle. How are they supposed to work, and why don’t they? That free energy or perpetual motion machines don’t work is a given, because of the laws of thermodynamics. Energy has to come from somewhere, so for each such claim it’s a fun game to figure out where the energy is actually coming from. This game also helps dispel any notion of continuous or free energy.

A new perpetual motion claim is revealed in an article in the Rob Report. The claims is for an electric plane that will fly mostly with the energy generated by the friction of the flying itself. The idea is that the plane will have rechargeable electric batteries that are used for take-off and landing. But while in flight, the batteries will be recharged by vibrations and the flexing of the wings. The inventor, Michal Bonikowski, who calls his project Eather One, hopes this will yield enough energy to keep the plane flying indefinitely.

The problem with this concept, as with all perpetual motion concepts, is the second law of thermodynamics. Every time you change energy from one state to another, at least a little bit is lost. You can never have 100% efficiency. So the energy you use to propel the plane forward will have to be greater than the energy you harvest from pushing through the air. If you design a mechanism (as in the concept art) for harvesting air friction, the extra resistance from the mechanism will cause the plane to slow by more than using that energy to propel it will increase its speed. The entire process will be a net negative. You would be better off optimizing aerodynamics.

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