From November 26 – Dec. 3, Athene’s Prophecy will be discounted to 99c/99p on Amazon. Science fiction with some science you can try your hand at. The story is based around Gaius Claudius Scaevola, given the cognomen by Tiberius, who is asked by Pallas Athene to do three things before he will be transported to another planet, where he must get help to save humanity from total destruction. The scientific problem is to prove the Earth goes around the Sun with what was known and was available in the first century. Can you do it? Try your luck. I suspect you will fail, and to stop cheating, the answer is in the following ebook. Meanwhile, the story. Scaevola is in Egypt for the anti-Jewish riots, then to Syria as Tribunis laticlavius in the Fulminata, then he has the problem of stopping a rebellion when Caligulae orders a statue of himself in the temple of Jerusalem. You will get a different picture of Caligulae than what you normally see, supported by a transcription of a report of the critical meeting regarding the statue by Philo of Alexandria. (Fortunately, copyright has expired.). First of a series. http://www.amazon.com/dp/B00GYL4HGW
Most people seem to think that science marches on inexorably, gradually uncovering more and more knowledge, going in a straight line towards “the final truth”. Actually, it is far from that, and it is really a lurch from one point to another. It is true science continues to make a lot of measurements, and these fill our banks of data. Thus in organic chemistry, over the odd century or so we have collected an enormous number of melting points. These were obtained so someone else could check whether something else he had could be the same material, so it was not pointless. However, our attempts to understand what is going on have been littered with arguments, false leads, wrong turns, debates, etc. Up until the mid twentieth century, such debates were common, but now much less so. The system has coalesced in acceptance of the major paradigms, until awkward information comes to light that is sufficiently important that it cannot be ignored.
As an example, currently, there is a debate going on relating to how elements like gold were formed. All elements heavier than helium, apart from traces of lithium, were formed in stars. The standard theory says we start with hydrogen, and in the centre of a star, where the temperatures and pressures are sufficient two hydrogen atoms combine to form, for a very brief instant, helium 2 (two protons). An electron is absorbed, and we get deuterium, which is a proton and a neutron combined. The formation of a neutron from a proton and an electron is difficult because it needs about 1.3 MeV of energy to force it in, which is about a third of a million times bigger than the energy of any chemical bond. The diproton is a bit easier because the doubling of the positive field provides some supplementary energy. Once we get deuterium, we can do more and eventually get to helium 4 (two protons, two neutrons) and then it stops because the energy produced prevents the pressure from rising. The inside of the sun is an equilibrium, and in any given volume, a surprisingly few fusion reactions take place. The huge amount of energy is simply because of size. However, when the centre starts to run out of hydrogen, the star collapses further, and if it is big enough, it can start burning helium to make carbon and oxygen. Once the supply of helium becomes insufficient, if the star is large enough, a greater collapse happens, but this refuses to form an equilibrium. Atoms fuse at a great rate and produce the enormous amount of energy in a supernova.
What has happened in the scientific community is that once the initial theory was made, it was noticed that iron is at an energy minimum, and making elements heavier than iron absorb energy, nevertheless we know there are elements like uranium, gold, etc, because we use them. So how did they form? The real short answer is, we don’t know, but scientists with computers like to form models and publish lots of papers. The obvious way was that in stars, we could add a sequence of helium nuclei, or protons, or even, maybe, neutrons, but these would be rare events. However, in the aftermath of a supernova, huge amounts of energy are released, and, it is calculated, a huge flux of neutrons. That 1.3 MeV is a bit of a squib to what is available in a supernova, and so the flux of neutrons could gradually add to nuclei, and when it contained too many neutrons it would decay by turning a neutron into a proton, and the next element up, and hence this would be available form further neutrons. The problem though, is there are only so many steps that can be carried out before the rapidly expanding neutron flux itself decays. At first sight, this does not produce enough elements like gold or uranium, but since we see them, it must have.
Or must it? In 2017, we detected gravitational wave from an event that we could observe and had to be attributed to the collision of two neutron stars. The problem for heavy elements from supernovae is, how do you get enough time to add all the protons and neutrons, more or less one at a time. That problem does not arise for a neutron star. Once it starts ejecting stuff into space, there is no shortage of neutrons, and these are in huge assemblies that simply decay and explode into fragments, which could be a shower of heavy elements. While fusion reactions favour forming lighter elements, this source will favour heavier ones. According to the scientific community, problem solved.
There is a problem: where did all the neutron stars come from? If the elements come from supernovae, all we need is big enough stars. However, neutron stars are a slightly different matter because to get the elements, the stars have to collide. Space is a rather big place. Let over all time the space density of supernovae be x, the density of neutron stars y, and the density of stars as z. All these are very small, but z is very much bigger than x and x is almost certainly bigger than y. The probability of two neutron stars colliding is proportional to y squared, while the probability of a collision of a neutron stars another star would be correspondingly proportional to yz. Given that y is extremely small, and z much bigger, but still small, most neutron stars will not collide with anything in a billion years, some will collide with a different star, while very few will collide with another neutron star. There have been not enough neutron stars to make our gold, or so the claims go.So what is it? I don’t know, but my feeling is that the most likely outcome is that both mechanisms will have occurred, together with possible mechanisms we have yet to consider. In this last respect, we have made elements by smashing nuclei together. These take a lot of energy and momentum, but anything we can make on Earth is fairly trivial compared with the heart of a supernova. Some supernovae are calculated to produce enormous pressure waves, and these could fuse any nuclei together, to subsequently decay, because the heavy ones would be too proton rich. This is a story that is unfolding. In twenty years, it may be quite different again.
By now it is probably apparent that SARS-CoV-2 is making a comeback in the Northern Hemisphere. Why now? There is no good answer to that, but in my opinion a mix of three aspects will be partly involved. The first is a bit of complacency. People who have avoided getting infected for a few months tend think they have dodged the bullet. They would have, but soldiers know that you cannot keep dodging bullets forever; either you do something about the source or get out of there. In the case of the virus, sooner or later someone with it will meet you. You can delay the inevitable by restricting your social life, but most people do not want to do that forever.
The second may be temperature. Our Health Department has recommended that places where people congregate and have heating systems should raise the temperature to 18 degrees C from the 16 currently advocated. Apparently even that small change restricts the lifetime of the virus adhering to objects, and viruses exhaled have to settle somewhere. This won’t help from direct contact, but it may prevent some infections arising from touching some inert object. That can be overcome by good hygiene, but that can be a little difficult in some social environments. My answer to that is to have hands covered with a gel that has long-term antiviral activity. (Alcohol evaporates, and then has no effect.)
The third is the all-pervasive web. It seems to be unfortunate that the web is a great place for poorly analysed information. Thus you will see claims that the disease is very mild. For some it is, but you cannot cherry-pick and use that for a generalization. If you say, “Some, particularly the very young, often only show mild symptoms,” that is true, but it identifies the limits of the statement. For some others the disease is anything but mild.
A more perfidious approach is the concept of “herd immunity”. The idea is that when a certain fraction of the population have been infected, the virus runs out of new people to infect, and once the infection rate falls below 1 it means the virus cannot replace itself and eventually it simply dies out. Where that value is depends on something called Ro, the number of people on average that the virus spreads itself to. This has to be guessed, but you see numbers tossed around like herd immunity comes when 60% of the people are infected. We then have to know how many have been infected, and lo and behold, you find on the web that a couple of months ago estimates said we were nearly there in many countries. The numbers of infections were guessed, and given the current situation, were obviously wrong. It is unfortunate that many people are insufficiently sceptical about web statements, especially those where there is a hidden agenda.
So, what is the truth about herd immunity? An article in Nature 587, 26-28 (2020) makes a somewhat depressing point: no other virus has ever been eliminated through herd immunity, and further, to get up to the minimum required infection rate in the US, say, will, according to the Nature paper, mean something like one to two million deaths. Is that a policy? Worse, herd immunity depends on the immunity of those infected to remain immune when the next round of viruses turn up, but corona viruses, such as those found in the common cold, do not give immunity lasting over a year. To quote the Nature paper, “Attempting to reach herd immunity via targeted infections is simply ludicrous.”
The usual way to gain herd immunity is with a vaccine. If sufficient people get the vaccine, and if the vaccine works, there are too few left to maintain the virus, although this assumes the virus cannot be carried by symptom-free vaccinated people. The big news recently is that Pfizer has a vaccine they claim is 90% effective in a clinical trial involving 43,538 participants, half of which were given a placebo. (Lucky them! They are the ones who have to get the infection to prove the vaccine works.) Moderna has a different vaccine that makes similar claims. Unfortunately, we still do not know whether long-term immunity is conveyed, and indeed the clinical trial still has to run for longer to ensure its overall effectiveness. If you know you have a 50% chance of getting the placebo, you may still carefully avoid the virus. Still, the sight of vaccines coming through at least parts of stage 3 trials successfully is encouraging.
The Moon is generally considered to be dry. There are two reasons for that. The first is the generally accepted model for the formation of our moon is that something about the size of Mars collided with Earth and sent a huge amount of silica vapours into space at temperatures of about 10,000 degrees Centigrade (which is about twice as hot as the average surface of the sun) and much of that (some say about half) condensed and accreted into the Moon. Because the material was so hot and in a vacuum, all water should have been in the gas phase, and very little would condense so the Moon should be anhydrous deep in the interior. The fact its volcanic emissions have been considered to be dry is taken to support that conclusion. And thus with circular logic, it supports the concept that Earth formed by objects as large as Mars colliding and forming the planet.
The second is the rocks brought back by Apollo were considered to be anhydrous. That was because the accepted paradigm for the Moon formation required it to be dry. The actual rocks, on heating to 700 degrees Centigrade, were found to have about 160 ppm of water. On the basis that the accepted paradigm required them to be anhydrous it was assumed the rocks were contaminated with water from Earth. The fact that the deuterium levels of the hydrogen atoms in this water corresponded to solar hydrogen and not Earth’s water was ignored. That could not be contamination. Did that cause us to revise the paradigm? Heavens no. Uncomfortable facts that falsify the accepted theory have to be buried and ignored.
Recently, two scientific papers have concluded that the surface of the Moon contains water. Yay! If we go there, there is water to drink. Well, maybe. First, let’s look at how we know. The support is from infrared spectra, where a signal corresponding to the O-H bond stretching mode is seen. It has been known for some time that such signals have been detected on the Moon, but this does not mean there is water, since it could also arise from entities with, say, a Si-O-H group. Accordingly, it could come from space weathered rock, and in this context, signal strength increases towards the evening, which would happen if the rocks reacted with solar wind. The heating of rocks with these groups would give off water, so the Moon might still be technically dry but capable of providing water. Further examination of apatites brought back from Apollo suggested the interior could have water up to about 400 ppm.
How could the interior be wetter? That depends on how it formed. In my ebook, “Planetary Formation and Biogenesis” I surveyed the possibilities, and I favour the proposal outlined by Belbruno, E., Gott, J.R. 2005. Astron. J. 129: 1724–1745. Quite simply, Theia, the body that collided with Earth, formed at one of the Lagrange points. I favour L4. Such a body there would accrete by the same mechanism as Earth, which explains why it has the same isotopes, and while its orbit there is stable while it is small, as soon as it becomes big it gets dislodged. It would still collide with Earth, it would still get hot but need not vaporize. Being smaller, the interior may trap its water. There is evidence from element abundance that anything that would remain solid on the surface at about 1100 degrees Centigrade was not depleted, which means that is roughly the maximum temperature reached, and that would not vaporize silicates.
In one of the new papers, the signals from the surface have included the H-O-H bending frequency, which means water. Since it has not evaporated off into space it is probably embedded in rocks and may have originated from meteorites that crashed into the Moon, where they melted on impact and embedded the water they brought. There is also ice in certain polar craters that never see the sunlight, and above latitude 80 degrees, there are a number of such small craters.So, what does this mean for settlement? If the concentration is 5 ppm, to get 5 kg of water you would have to process a thousand tonne of rock, which would involve heating it to about seven hundred degrees Centigrade, holding it there, and not letting any water escape. The polar craters have ice up to a few per cent, but that ice also contains ammonia, hydrogen sulphide, and some other nasties, and since the craters never see sunlight the outside temperature is approximately two hundred degrees Centigrade below zero. You will see proposals that future space ships will use hydrogen and oxygen made from lunar water. That would require several thousand tonne of water, which would involve processing a very large amount of rock. It will always be easier to get water from the Sahara desert than the lunar surface, but it is there and could help maintain a settlement with careful water management.
What is the point of a scientific theory? The obvious one is that if you understand you can predict what will happen if you have reason to have that proposition present. Unfortunately, you can lay down the principles and not make the specific prediction because you cannot foresee all the possible times it might be relevant. What sparked this thought is that about a decade ago I published an ebook called “Planetary Formation and Biogenesis”. The purpose of this was in part because the standard theory starts off by assuming that somehow things called planetesimals form. These were large asteroids, a few hundred km in size, and then these formed planets through their mutual gravity. However, nobody had any idea at all how these planetesimals formed; they were simply assumed as necessary on the assumption that gravity was the agent that formed the planets. On a personal level, I found this to be unsatisfactory.
I am restricting the following to what happens with icy bodies; the rocky ones are a completely different story. We start with highly dispersed dust because the heavy elements are formed in a supernova, in which these gases fly out at a very high speed. In one supernova, one hour after initiation, matter was flying out at 115,000 km/second, and it takes a long time to slow down. However, eventually it cools, gets embedded in a gas cloud and some chemical reactions take place. Most of the oxygen eventually reacts with something. All the more reactive elements like silicon or aluminium react, and the default for oxygen is to form water with hydrogen. The silicon, magnesium, calcium and aluminium oxides form solids, but they form one link at a time and cannot rearrange. This leaves a dispersion of particles that make smoke particles look large. If two such “particles” get close enough, because the chemical bonds are quite polar in these particular oxides, they attract each other and because they are reactive, they can join. This leads to a microscopic mass of tangled threads since each junction is formed on the exterior. So we end up with a very porous solid with numerous channels. These channels incorporate gases that are held to the channel surfaces. In the extreme cold of space, when these gases are brought close together on these surfaces they solidify to form ices. These solids filled with ices have been formed in the laboratory.
My concept of how icy bodies accrete goes like this. As the dust comes into an accretion disk where a star is forming, as it approaches the star it starts to warm. If particles collide at a temperature a little below the melting point of an ice they contain, the heat of collision melts the ice, the melt flows between the bodies then refreezes, gluing the bodies together. The good news is this has been demonstrated very recently in the laboratory for nanometer-sized grains of silicates coated with water ice (Nietadi et al., Icarus, (2020) 113996) so it works. As the dust gets warmer than said melting point, that ice sublimes out, which means there are four obvious different agents for forming planets through ices. In increasing temperatures these are nitrogen/carbon monoxide (Neptune and the Kuiper Belt); argon/methane (Uranus); methanol/ammonia/water (Saturn); and water (Jupiter). The good news is these planets are spread relatively to where expected, assuming the sun’s accretion disk was similar to others. So, in one sense I had a success: my theoretical mechanism gave planetary spacings consistent with observation, and now the initial mechanism of joining for very small-scale particles has been shown to work.
But there was another interesting point. Initially, when these fluffy pieces meet, they will join to give a bigger fluffy piece. This helps accretion because if larger bodies collide, the fluff can collapse, making the impact more inelastic and thus dispersing collisional energy. Given a reasonable number of significant collisions, the body will compact. If, however, there are some late gentle acquisitions of largish fluffy masses, that fluff will remain.Unfortunately, I did not issue a general warning on this, largely because nobody can think of everything, and also I did not expect that to be relevant to any practical situation now. Rather unexpectedly, it was. You may recall that the European Space Agency landed the probe Philae on comet 67P/Churyumov–Gerasimenko, which made a couple of bounces and fell down a “canyon”, where it lay on its side. The interesting thing is the second “bounce” was not really a bounce. The space agency has been able to use the imprint of the impact to measure the strength of the ice, and found it to be “softer than the lightest snow, the froth on your cappuccino or even the bubbles in your bubble bath.” This particular “boulder” on the outside of the comet is comprised of my predicted fluff. It feels good when something comes right. And had ESA read my ebook, maybe they would have designed Philae slightly differently.