Environment Long Read Science

A Lockdown in Science (April – September 2020)

Author’s Note: We’re back! Unfortunately, there’s a lot less content here than you might hope, so these articles will likely have to be bi-monthly (every other month) to compensate. Also, as per my pre-lockdown policy, no COVID allowed.

Physics

Black hole mergers are significant: the two objects produce gravitational waves as they circle in towards each other. The observation of gravitational waves, confirmed in 2015, later won a Nobel Prize. And black hole mergers have continued to fascinate and perplex researchers, as recent observations have shown a black hole merger between two objects, at least one of which lies in a “forbidden” mass range. We can estimate the masses of the involved black holes based on the frequency of the gravitational waves we receive, which increases exponentially as the objects get closer until cutting out once the two merge. The cut-off frequency depends on the mass of the two involved black holes: the larger the black holes, the lower the frequency. The estimated masses of the black holes in question lie at 66 and 85 solar masses, the former of which lies squarely between the two already known mass ranges of star collapse black holes and supermassive black holes. The heavier black hole also, to our knowledge, lies within the pair instability gap, a mass range within which we predict 0 black holes should fall, as any stars massive enough to form such black holes would become too hot as they die out, exploding in “special” supernovae that don’t leave behind any remnants of the star. Read further about these observations here.

Further, that was not the only significant black hole merger recorded as of late. Recent observations out of LIGO have revealed a black hole merger that breaks new ground. This time, it was a merger between two black holes of significantly different masses; in this case, the larger black hole was over 3 times more massive than the smaller of the two. The result of this irregularity? The smaller black hole did not spiral in perfectly, instead it followed a distorted path inward. This difference also manifested in not a single rising “chirp” frequency, but in two distinct frequencies of gravitational waves. This observation also led astronomers to find that the larger black hole was spinning! Truly, it’s the oddballs that most interest us in the world of science. Read further here.

Quasiparticles are a phenomenon whereby some complicated systems behave as though they contain different particles in a vacuum. Essentially, they are a simpler abstraction of a smaller system, just like how particles are a simplified abstraction of excitations in quantum fields. For example, the idea of ‘electron holes’ in the valence band of a semiconductor is a quasiparticle. Another example of this is a particle whose existence was first proposed in 1977; anyons, first coined as such in 1982, are a type of quasiparticle which occurs in two-dimensional systems. The emergent behaviours of anyons are far less restricted than bosons and fermions due to a variable factor applied to their wavefunctions, “e“, whereas bosons and fermions would have a factor of “1” and “-1” respectively. Anyons are split into two categories: abelian and non-abelian. The key distinction between these two types lies in whether they commute. That is, for an abelian set of numbers a and bab=ba, whilst for a non-abelian set, this equivalence does not hold. Recently, the existence of abelian anyons has been confirmed by a team of researchers at École normale supérieure (Paris). Excitingly, there are already theoretical models of more powerful quantum computers which utilise the now confirmed anyons as their basis. We very well may be looking at a technological revolution in the making! However, the next step for these quasiparticles is to find non-abelian anyons, which (although still unconfirmed) are the basis of these designs. Read further about this discovery here.

The mark of a great theory or an elegant model is that it makes clear predictions: when we can say “this model makes this prediction and will be false if it doesn’t happen”, then we know we are dealing with a great model. And that is exactly the kind of model we have of our Sun. Specifically, our stellar model predicts a concentration of metals (to astronomers, metals are anything heavier than helium) in the Sun that allows for the carbon-nitrogen-oxygen (CNO) cycle to occur within the star. This cycle is an alternative method of converting hydrogen to helium from the proton-proton (PP) chain reaction and the CNO cycle is thought to be responsible for a majority of the energy released by large stars. Both processes produce neutrinos, ghostly particles that barely interact with regular matter (the rough figure is that 1 in 1025 neutrinos will actually interact with you instead of passing through you). Helpfully, the CNO cycle produces neutrinos at different energy ranges than the PP chain, thus we can actually distinguish the difference! And at the Neutrino 2020 conference, it was announced that the Borexino experiment, first started in 2007, had detected CNO neutrinos from our sun, finally confirming our stellar model. For further (more technical) information, read the paper published on the results.

The Large Hadron Collider (LHC) at CERN is one of the greatest feats of engineering ever. It has produced some of the most significant results in modern particle physics ever, not least of which the first ever observation of the Higgs boson. It collides protons at energies up to 13TeV (which is actually a very small amount of energy, but given the scales we’re working at here, it’s extremely high, being the equivalent to 13 teravolts – or 43 million times your mains electricity – if scaled up). And now that this document has been approved, we are looking at the distinct possibility, even probability, that the LHC, even after its upgrade to be finished in 2027, will soon be dwarfed by two new supercolliders, each even more powerful than the LHC. First, a 100km tunnel hosting an electron-positron collider is to be created in the hopes of further studying the Higgs boson. The plan would later see this collider dismantled and then replaced by another proton-proton collider, this time reaching energies of 100TeV. Of note, is that the technology required to develop the latter of the two colliders does not yet exist! However, with the current plans putting the construction of the second collider somewhere in the mid-21st century, we still have plenty of time to make this new dream piece of scientific equipment a reality.

Fast radio bursts (FRBs) are among the most violent and energetic phenomena in the universe. They are, as named, fast (around the millisecond timescale) bursts of radio waves at very high intensities (extrapolating for the luminosities puts these bursts around the same magnitude as the sun, but whilst comprising only of radio waves, which are each less energetic than visible light by a factor of at least 107). Many theorists posited that these FRBs come from magnetars, neutron stars with incredibly strong magnetic fields and these theories are looking increasingly likely, as recent observations of SGR 1935+2154, a magnetar in our own Milky Way, showed what looks to be an FRB over 10,000 times closer than any we have seen before. There are still questions about these observations, such as why its intensity is around 1,000 times lower than any other recorded FRB and how FRBs could repeat in the manner some have if their sources are magnetars. However, these observations are a promising development and could provide the first insights into these phenomena. Read further here.

Parallax is a time-honoured method of calculating distances. It is to such an extent that it’s how you judge distances with your eyes; that is, of course, the reason why we have two of the things. Parallax uses the principle that observing an object from two different places will result in it appearing to move position. For example, taking two photos of a computer screen, 1m apart from each other, would result in some apparent shift in the position of the screen; this shift is measured as an angle and as long as we know the distances between our two observers (or eyes) we can calculate the distance to our screen. This concept is also used on nearby stellar objects: as the Earth orbits the Sun, we can observe the smallest shifts in position, usually measured in arcseconds (1/3600th of a degree), of the closest stars. The New Horizons space probe, first launched in 2006, has recently taken measurements of some nearby stars, Wolf 359 and Proxima Centauri. Whilst other measurements, such as those of the Gaia probe, have extensively logged distances to thousands of stars by using the Earth’s orbit, the miniscule difference can only really be appreciated by putting it into a table of numbers. With these new measurements, taken with a displacement 23 times greater than that of Gaia, you can see the difference.

The ESA’s Solar Orbiter, launched in February 2020, has recently released its first images of the sun. These images, taken at only half the distance from the Earth to the sun, are the closest ever. Whilst there are other missions that have gotten as many as 10 times closer than the Solar Orbiter, the heat they experience is so intense that they don’t carry cameras facing the sun. The images taken by the Solar Orbiter are arguably the best ever. Whilst grounded telescopes have taken higher resolution photos before, they have a distinct disadvantage: the atmosphere. The same atmospheric phenomenon that makes the sky blue foils our astronomy as it confounds our every attempt to observe certain UV wavelengths of light. The Solar Orbiter doesn’t suffer from this problem and promises even more high quality photographs, as well as a range of other measurements as it continues operating into the future.

Mars has always been a planet of much fascination to astronomers the world over. Not least of the reasons being the presence of liquid water on the planet’s surface. But also, there is of course our endless fascination with potential locations to colonise. Call it modern day imperialism if you will, but there’s something very cool about the idea of a moon base, or, dare I say it? A base on Mars. Of course, we’re far from that dream as it stands, but even amidst the COVID-19 pandemic, we are still progressing towards a future where we can put men on Mars. And in the month of July, not one, not two, but three missions to Mars have been launched by the United Arab Emirates, the United States and China. With this newfound international interest in space exploration, we truly seem to be entering a new era of discovery.

In March 2020, SpaceX became the first private company ever to launch a crew of humans into space. SpaceX’s Dragon spacecraft had already launched more than 20 times carrying payloads up to 6 tons on launch and 3 tons coming back to Earth.  This version of the Dragon capsule, “Crew Dragon”, is the product of several new iterations since the first Dragon 1’s launch. It marks the return of space travel to the US, since the retirement of the space shuttle in 2011 and is a key milestone in NASA’s plan to outsource space travel to private firms in future years. Read further about Dragon here.

In 2018, a salt water lake was discovered beneath the south pole of Mars from 29 radar observations of the red planet over the course of 3 years. Now, in 2020, after collating 134 observations from 2012 to 2019, three more bodies of water have been discovered. However, all of these discoveries are swamped in controversy: many geologists don’t believe the observed bodies could be liquid water, siting an apparent lack of any reasonable heat source. Mike Sori, a planetary geologist says “If the bright material really is liquid water, I think it’s more likely to represent some sort of slush or sludge.” Nevertheless, we can say with near-certainty that there are some sort of bodies of liquid beneath the surface of Mars. Not as appealing of a headline, but still a significant advancement nonetheless. Read further here.

Last year, the first ever image of a black hole was released to the public after an international network of radio telescopes collated their observations to form a “planet-sized telescope” based on mathematical models, which compensate for a lack of an actual planetary telescope by combining observations from across the planet and “filling in the gaps”. This collaboration, called the Event Horizon Telescope (EHT), has continued it’s efforts and this year, they extrapolated this technique further to create a “movie” of the black hole, modelling how it has changed over the past few years. Read further here.

Biology (and Biochemistry)

Recent trials of CRISPR, a technique lauded as the future of gene-editing, have revealed a potentially devastating range of unwanted effects. The technique, which is based on the immune systems of bacteria, has undergone a number of tests on human embryos. These tests reaffirmed the flaws in CRISPR which we already knew, that sometimes it can be really, REALLY off. But this was not the main issue that these tests raised: the real problem is that these tests revealed that CRISPR can also make mistakes close to the intended site. Whilst CRISPR sometimes veers off course, it does so to such a large extent that we can immediately recognise these “off-site” errors. The real issue is that CRISPR, according to recent studies that have yet to be peer-reviewed, also appears to cause damage to genes near the intended target. Several causes of this have been proposed, but this does constitute a worrying development with regards to the future of this technique, especially for use in humans. Read further here.

Cryo-electron microscopy, a technique which earned a Nobel Prize for it’s revolutionary implications on organic chemistry, has reached perhaps the most significant milestone possible: it has reached “atomic resolution”. That is, it has produced an image at such a high resolution, that individual atoms are visible and distinguishable from one another. This milestone finally puts Cryo-EM squarely ahead of its predecessor, in the technique of X-ray crystallography. Cryo-EM has always held the advantage of requiring only a purified solution to image a molecule, as opposed to the requirement of a fully crystallised structure for X-ray crystallography (which can take years, not to mention that some structures never crystallise at all!). However, it could never reach atomic resolution; that level of precision was never available for Cryo-EM. But with advancements in technology – from more sensitive cameras to more powerful computers – we have finally achieved that sweet, sweet atomic resolution! Read further here.

Charcoal is made by strongly heating wood to leave a carbon residue similar to regular coal. Almost half of it is produced using tropical wood, but only a very small proportion of it is certified sustainable. This raises several ethical concerns, most of all that this charcoal could be the result of illegal logging. Using microscopy, it is possible to digitally reconstruct images of the original wood, which can then be used to identify the wood as precisely as its genus. A recent study found that only a quarter of charcoal bags contain information about the origin of the wood and of those, about half were either incomplete, or just plain wrong! Find the study here.

We all know about photosynthesis to some extent. It is the process behind life on Earth and it’s the only process by which we can remove CO2 from the atmosphere. Well, that’s not really true. In fact, photosynthesis is not even the most efficient pathway to convert CO2 into sugar that we know of. Recently, researchers have discovered a pathway, the CETCH cycle, which is around 20% more efficient than photosynthesis pathways in plants. With this pathway in mind, researchers have produced an artificial chloroplast using spinach membranes to collect solar energy and the CETCH cycle to break down CO2. Whilst the technology is still in its early days, this being the proof of concept, this could be a promising development in multiple areas of chemical industry, as CETCH could not only be used to produce several inorganic compounds, but I could also be carbon negative while it does so! Read further here.

Mathematics

The abc conjecture is one of the most famous and important unsolved problems in number theory. It, much like other famous conjectures such as Fermat’s last theorem, is closely related to prime numbers. And it, much like Fermat’s last theorem, has been subject to false proof in the past. However, in 2017, a Japanese mathematician, Shinichi Mochizuki, published 4 papers which developed a new theory (Inter-universal Teichmüller theory or IUTT) of his creation. Stunningly, these papers also appeared to include proofs of several outstanding problems in number theory, the abc conjecture included. However, this proof has been subject to extreme controversy: not only were the papers extremely long and hard to understand, which is poor form, but they also appeared to include a major logical gap, which would require serious reworking of the entire proof to remedy. However, Mochizuki maintained the correctness of the proofs and never made any alterations to his papers. Nevertheless, after years of struggle, Mochizuki’s papers have been accepted for publication by Publications of the Research Institute for Mathematical Sciences (RIMS). Read further about this development here.

About the author

Tristan Jacquel

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