Neutrinos & Neŭtrinoj

Okay, let’s just go hell for leather on this. Most of it is just going to come out of my head.

When I was seven, I was really interested in nuclear physics. I had this naive idea that if I knew everything all matter and forces were made of down to the smallest level, I would effectively know everything, full stop. The error of this thought was borne in upon me when I realised I had no idea what the scientific name of the freshwater shrimp was, anything about that animal’s anatomy and so on, and more broadly that just because you knew everything about the building blocks of everything in the Universe didn’t mean you knew much about the things that were made of ’em. Seven year olds, eh?

However, one thing that did impinge upon my learning was that atoms were made up of electrons orbiting a nucleus made of neutrons and protons, that the nuclei were held together by the strong nuclear force carried by pions, light was made up of photons, and protons and neutrons were part of a larger class of fairly massive particles called hadrons, which were generally composed of smaller particles called quarks held together by gluons. This is now such a long time ago that nuclear physics has changed considerably since then and some of the ideas are very outdated. For instance, at one point it was thought that quarks were made up of smaller particles called “rishons”, whose number of types enabled the standard model to be simplified by seeing them as pairs of rishons of a few kinds. Only two types of rishons would be needed for there to be four types of quark. Also back then, the top and bottom quarks had yet to be detected, so people mainly talked about up, down, strangeness and charm, and it hasn’t been lost on me that that’s the title of a Hawkwind album. This was, however, about three years before the album came out and at the time I would’ve been entirely contemptuous and condescending about this piece of music with pretentions to be high art. I should hastily add that I’m not like that any more.

Now it was quite easy for my undeveloped child’s mind to understand all this. Basically, each particle had mass, charge (or no charge) and spin, and these properties defined what that particle was. They were divided into bosons and fermions, and also leptons, mesons and baryons according to their mass from light to heavy. I was for some reason particularly excited about mesons. Many of these particles are unstable, and when they break up their mass, charge and spin need to be conserved. To take a completely wrong example, say there’s a meson with a mass five hundred times that of an electron. If it broke up into two smaller particles, if each has a mass 250 times that of an electron, that would conserve mass. However, this is totally wrong because some of a particle’s mass is lost in binding energy, so each of the pair would actually have a mass more than half of the meson’s. That’s not in any way a real example but because I’m ploughing on at a rate of knots, I’m not looking any details up and can’t remember the properties of a pion, for example. Leptons, incidentally, are not like that. They’re stable, lighter and not made of anything smaller. This is about mesons and baryons. If you asked my seven-year old self, I’d be able to give you the properties, but my late middle-aged and addled brain can no longer so do.

But, more simply, if a neutral particle emits an electron it will become positively charged because electrons are negatively charged and that needs to be preserved.

Not all objects have mass at all. If an object has a mass of zero, it has no choice but to move at the speed of light, which is actually not the specific speed of light but just the fastest speed there is, to quote Monty Python. Neither must every object have charge. Most objects we come across in everyday life, such as combs and loo rolls, tend to have no charge most of the time although if you comb hair with a comb it will become charged and be able to pick up small bits of loo roll, so it does happen. On a subatomic scale, though, there are essentially charged particles, namely the electrons and protons making up atoms, but there also have to be the uncharged neutrons which balance out the nucleus and prevent it exploding. Both protons and neutrons are made up of charged quarks which together add up to one unit of positive charge or no charge because they cancel each other out or they don’t. So that’s also simple.

Spin is however really not simple. Although this makes no sense to our macroscopic brains, spin is quantised and a property like charge and mass. Also, even more strangely, a particle can have non-integral spin, and if it does, it needs to be flipped over twice to reverse its spin. Look at it this way: there’s a gyroscope spinning in a clockwise direction when viewed from above. Usually, to make it spin anticlockwise all you need to do is turn it upside down. If, however, it had non-integral spin, if you turned it upside down, it still wouldn’t be spinning anticlockwise and you’d have to flip it over again to make it spin the other way. This is very weird and as I’m typing this I wonder if I’ve got it wrong but it’s been said that if you think you understand quantum mechanics, you don’t understand it, so presumably I do understand this because I don’t.

So why am I bothering to mention this little detail? Well, it was discovered some time ago that the way subatomic particles break down must conserve mass (taking into account that some of their mass is converted to energy when they’re stuck together), electrical charge and also this other property, spin. In order for this to work properly, there must be massless and chargeless particles. These particles seem to be nothing, but they aren’t because they have spin. These are neutrinos, and they come in various types because they’re leptons and they have corresponding more tangible particles, so there are for example muon’s neutrinos and electron’s neutrinos. They are of course bloody weird. The way they’re detected is by filling enormous buried underground tanks with dry cleaning fluid and trying to detect the tiny number of atoms which are changed by interaction with them. Since they’re produced in nuclear reactions, the Sun emits them. It’s been said that a million neutrinos passed through a wall of lead a light year thick, almost all of them would come out the other side. They virtually do not interact with matter. About forty-odd years ago, there was a problem understanding the Sun because it wasn’t producing enough neutrinos. In other words, the massive tanks of dry-cleaning fluid under the Alps or wherever they were kept were not producing detectable numbers of different atoms. I mean, I don’t know how you detect a couple of altered atoms in six hundred tonnes of dry cleaning fluid, but apparently you can. I’ve probably missed the point. Incidentally, I don’t want to go off on too much of a tangent but I find it kind of annoying that there is a thing called “dry-cleaning fluid“. How is it dry-cleaning then, eh? And while I’m at it, it used to be used to decaffeinate coffee, or something similar did, and it always used to give me a stomach ache when I drank it. Tangent alert!

Okay, so my point is that for whatever reason I didn’t have any problem accepting that neutrinos existed even though they were massless and practically didn’t interact with matter, at the age of seven. In fact, in 1987 it turned out that neutrinos did in fact have some mass because a couple of hundred thousand years ago, a star exploded in one of the Milky Way’s satellite galaxies and the neutrinos took a few seconds longer to get here than the light, implying that they were travelling more slowly than light and must therefore have mass.

Now for the famous problem.

Centuries ago, Johannes Kepler worked out that the time it takes a planet to orbit the Sun can be worked out straightforwardly from its distance. To quote Kepler’s Third Law, “the squares of the orbital periods of the planets are directly proportional to the cubes of the semi-major axes of their orbits”. Semi-major axis is the mean distance of a planet’s orbit from the Sun. Isaac Newton generalised this law to come up with the law of gravity, and it’s supposed to apply to everything in the Universe. There’s a lot more, but this is the important bit. It means that if you look, for example, at the triple star system next to the Sun, you can work out from the masses of Proxima Centauri, α Centauri A and B and their distances from each other how long it takes them all to orbit each other. The much closer A and B are close in mass to each other and take eighty years to orbit and Proxima, which is eleven thousand times the distance of Earth from the Sun, takes 550 thousand years to orbit the other two, whose total mass is what matters. However, it doesn’t stay this simple.

If you look at a galaxy, you might think you can calculate its mass from the number of stars in it and their sizes. Galaxies rotate very, very slowly: our solar system takes something like 225 million years to orbit its centre. It ought therefore to be expected that the time taken for a star twice as far out from the centre to orbit this galaxy should be the square root of the cube of twice as long as 225 million years, i.e. a little under three times as long. However, it actually only takes about twice as long. Why?

Obviously you can’t see everything in the Galaxy. If you were looking at this solar system from α Centauri, even with a fantastically powerful telescope, you wouldn’t be able to see Jupiter, any of the other planets or moons, any of the dwarf planets or any of the asteroids, and between the stars there are also rogue planets wandering in interstellar space, dust, maybe black holes and brown dwarf “stars” too dim to see as well as potential comets very slowly orbiting sheer light months from the Sun, so there definitely is missing mass which means galaxies would seem to rotate faster than just counting up the stars would predict, and also, coming back to neutrinos, they also increase the mass of galaxies somewhat. However, for this to work as a way of accounting for how fast galaxies spin, and also how quickly galaxies “near” each other affect each others’ motion, well over three-quarters of the mass of a galaxy would have to consist of this sort of stuff. Maybe it does, but it probably doesn’t because for example 99.8% of the mass of our solar system is the Sun. Therefore it probably isn’t lots of ordinary invisible matter doing this.

Therefore, scientists decided that there must be something called WIMPs – Weakly Interacting Massive Particles. This is by contrast with MACHOs – MAssively Compact Halo Objects – which is the idea that there’s a roughly spherical cloud of massive ordinary matter also orbiting galaxies outside the plane of the arms. I’m about to come to the point by the way. To me, and to a lot of other people, WIMPs seem to be invented just to explain the problem. They’re most of the matter in the Universe, but they conveniently do not interact with the matter we’re familiar with. I paused there because I almost wrote “do not interact with ordinary matter”, but in fact if this is true they actually are “ordinary” matter, and it’s atoms, molecules and light which aren’t, in other words all the stuff which can be detected. Hence I think this is silly and go with a different hypothesis, which is MoND – Modified Newtonian Dynamics. This is the idea that the explanation is that Newton’s laws of gravity only work on relatively small scales and break down if you consider them over thousands of light years or further.

All this said, I am perfectly well aware that I’m no physicist. I did have my doubts about the cosmological constant as a teenager but just thought it was because I didn’t understand physics, then it turned out Albert Einstein had the same doubts and found it embarrassing, so maybe I should listen to my intuition more. Maybe people can be too embedded in their area of expertise to realise the flaws in their thoughts. Or, maybe an outsider just doesn’t understand properly and only thinks she does.

But my point is not about this but ageing and how people accept and reject things as they get older. As a child, I liked the idea of neutrinos because they were absurd and weird, and therefore fascinating. As a fifty-seven year old, and in fact even when I was quite a bit younger, I find the idea of dark matter, which is what I’ve just described, hard to accept even though it’s quite similar in a lot of ways to neutrinos. And that’s the process of becoming more conservative as you get older, and therefore this now becomes not an abstruse argument about physics or cosmology but personality and maturity.

There has been a pattern where young people start off left wing and become right wing old people. This is apparently less true than it used to be. Why this happens is another question. It may be that as one acquires wealth and possessions, one realises that one’s position of poverty and the apparent need to depend on the state for financial support was temporary and would also be for other people, and therefore things will get better or easier if one takes responsibility for things. Or, it could be that as one’s career advances, one makes moral compromises and therefore descends into self-deception and rationalisation for them. Or, again, maybe it’s cognitive decline and an inevitable process of being more easily duped by politicians and media-based propaganda. Conservative ideas are more appealing because they’re about the “good old days”. If this last one is so, the answer to a drift to the right may be just to decide that one was more likely to have been correct before one started losing one’s marbles and freeze one’s political opinions at that stage, but when new situations arise it can be harder to apply those principles than it used to be.

Why has this image appeared at this point on this blog post? Well. . .

I accept that neutrinos exist. Once upon a time, in 1887 CE, a guy called Lazarus Zamenhoff living in Poland invented a language called Esperanto, which I’m sure you’ve heard of. It was designed to be simple and logical, and was specifically constructed in a Europe where the various powers had been at each others’ throats for centuries, so the vocabulary was mainly based on Romance, Germanic, Greek and Slavic roots, plus a few completely invented words. In order to make learning it easier, Zamenhoff introduced the idea that words could be plugged together to change their meaning in a completely regular way, so for example the prefix “mal-” would turn a word into its opposite: “bona” means “good”, “malbona” means “bad”, and more controversially, “knabo” means “boy” and “knabino” girl, and in fact in the original version of the language all the gendered terms are unmarked when masculine and marked when feminine in this way. This is sexist but there are practical reasons for it. As in natural languages which mark this kind of gender, there are ways of working round it.

One of the possible flaws in the language is what this approach to word building does to words which are similar in many languages. For instance, take the English word “school”. In French this is «école», in German ,,Schule”, in Indonesian “sekola” and so on. All words which look and sound similar. In Esperanto, the word for school is “lernejo” – “learn-place”. This is easy to form and break down, and it reduces the need to learn a more opaque word, but the chances are that in many cases the word will already exist in the learner’s native language and there may at least initially be some puzzlement.

Germaine Greer’s famous book is called ‘The Female Eunuch’ in English, the language it was written in. The Esperanto word for “eunuch” is the rather logical word “neŭtro”, related to the adjective “neŭtra”, meaning “neuter”. However, since unmarked nouns in Esperanto usually refer to males or inanimate items, “neŭtro” means “male eunuch”. “-Ino” is the feminising ending. Hence the Esperanto word for “female eunuch” is “neŭtrino”! I don’t know whether Greer’s book has been translated into Esperanto or what its title is if it has, and I also don’t know what the Esperanto word for the elementary particle is, but logic suggests that neutrinos are called something else in Esperanto and the word “neŭtrino” does in fact mean “female eunuch”. If not, the chances are that when Esperantists talk about fundamental particles they say that there are vast tanks of dry-cleaning fluid under the Alps intended to detect female eunuchs and that when scientists detected Supernova 1987A, they noticed that female eunuchs don’t move at the speed of light. Well I could’ve told ’em that.

So what’s my point? Do I have one? Surprisingly, yes. As I’ve got older, like many other people my acceptance of novelty has become less flexible and although I was fine with neutrinos I wasn’t fine with dark matter. Neutrinos were discovered in 1956, though they were theorised earlier. ‘The Female Eunuch’ was published in 1970. Esperanto had its rules laid down in 1887, and although better-designed versions of the language have been proposed since, it’s difficult to accept them because the whole point of Esperanto was that it was supposed to be a single language which everyone could use. I actually think Esperantido is loads better but I wouldn’t use it because it isn’t the original. This rigid design is reflected in the fact that these two concepts, the female eunuch and the neutrino, have happened in the world getting on for a century after the language was devised, but it isn’t open to accepting new ideas in that way. As such, Esperanto represents exactly what happens to us as we get older, but not because we compromise or become more conservative, but simply because we were designed for an earlier age, in the case of Esperanto, one where neutrinos were unknown and second-wave feminism was unthought of.

It occurs to me also that second-wave feminism itself has also been superceded and may be in the same position, but that’s another story.

The Anti-Universe

A prominent mythological theme is that of time being cyclical. For instance, in Hinduism there is a detailed chronology which repeats endlessly. Bearing in mind that the numbers used in mythological contexts are often mainly there to indicate enormity or tininess, there is the kalpa, which lasts 4 320 million years and is equivalent to a day in Brahma’s life. There are three hundred and sixty of these days in a Brahman year, and a hundred Brahman years in a Brahman lifetime, after which the cycle repeats. Within a Brahman Day, human history also repeats a cycle known as the Yuga Cycle, which consists of four ages, Satya, Treta, Dvapara and Kali. The names refer to the proportion of virtue and vice characterising each age, so Satya is perfect, life is long, everyone is kind to each other, wise, healthy and so on, satya meaning “truth” or “sincerity”, Treta is “third” in the sense of being three quarters virtue and one quarter vice, Dvapara is two quarters of each and Kali, unsurprisingly the current age, is the age of evil and destruction. Humans start off as giants and end as dwarfs. Then the cycle repeats. Thus there are cycles within cycles in Hindu cosmology.

The Maya also have a cyclical chronology, including the Long Count, in a cycle lasting 63 million years. Probably the most important cycle in Mesoamerican calendars is the fifty-two year one, during which the two different calendars cycle in and out of sync with each other. The Aztecs used to give away all their possessions at the end of that period in the expectation that the world might come to an end.

The Jewish tradition has a few similar features as well. Firstly, it appears to use the ages of people to indicate their health and the decline of virtue. The patriarchs named in the Book of Genesis tend to have shorter and shorter lives leading up to the Flood, which ends the lives of the last few generations before it, including the 969-year old Methuselah. Giants are also mentioned in the form of the Nephilim, although they are seen as evil. I wonder if this reflects the inversion of good and evil which took place when Zoroastrianism began, where previously lauded deities were demonised. There is also a cycle in the practice of the Jubilee, consisting of a forty-nine year Golden Jubilee and a shorter seven year Jubilee, and obviously there are the seven-day weeks, which we still have in the West.

The Hindu series of Yugas also reflects the Greek tradition of Golden, Silver, Bronze and Iron Ages, which was ultimately adopted into modern archæology in modified form as the Three-Age System of Stone, Bronze and Iron. The crucial difference between the Hindu and Greek age system and our own ideas of history is that they both believed in steady decline whereas we tend to be more mixed. We tend to believe in progress, although our ideas of what constitutes that do vary quite a lot. In a way, it makes more sense to suppose that everything will get worse, although since history is meant to be cyclical it can also be expected to get better, because of the operation of entropy. Things age, wear out, run down, burn out and so on, and this is the regular experience for everyone, no matter when they’re living in history, and it makes sense that the world might be going in the same direction. On the longest timescale of course it is, because the Sun will burn out, followed by all other stars and so on.

Twentieth century cosmology included a similar theory, that of the oscillating Universe. It was considered possible that the quantity of mass in the Universe was sufficient that once it got past a certain age, gravity acting between all the masses in existence would start to pull everything back together again until it collapsed into the same hot, dense state which started the Universe in the first place. There then emerge a couple of issues. Would the Universe then bounce back and be reborn, only to do it again in an endless cycle? If each cycle is an exact repetition, does it even mean anything to say it’s a different Universe, or is it just the same Universe with time passing in a loop?

This is not currently a popular idea because it turns out that there isn’t enough mass in the Universe to cause it to collapse against the Dark Energy which is pushing everything apart, so ultimately the objects in the Universe are expected to become increasingly isolated until there is only one galaxy visible in each region of the Universe where space is expanding relatively more slowly than the speed of light. This has a significant consequence. A species living in a galaxy at that time would be unaware that things had ever been different. There would be no evidence available to suggest that it was because we can currently see the galaxies receding, and therefore we can know that things will be like that one day, but they would have no way to discover that they hadn’t always been like this. This raises the question of what we might have lost. We reconstruct the history of the Universe based on the data available to us, and we’re aware that we’re surrounded by galaxies which, on the very large scale, are receding from each other, so we can imagine the film rewinding and all the stars and galaxies, or what will become them, starting off in the same place. But at that time, how do we know there wasn’t evidence of something we can no longer recover which is crucial to our own understanding of the Universe?

Physics has been in a bit of a strange state in recent decades. Because the levels of energy required cannot be achieved using current technology, the likes of the Large Hadron Collider are not powerful enough to provide more than a glimpse of the fundamental nature of physical reality. Consequently, physicists are having to engage in guesswork without much feedback, and this applies also to their conception of the entire Universe. I’ve long been very suspicious about the very existence of non-baryonic dark matter. Dark matter was originally proposed as a way to explain why galaxies rotate as if they have much more gravity than their visible matter, i.e. stars, is exerting. In fact, if gravity operates over a long range in the same way as it does over short distances, such as within this solar system or between binary stars, something like nine-tenths of the mass is invisible. To some extent this can be explained by ordinary matter such as dust, planets or very dim stars, and there are also known subatomic particles such as the neutrinos which are very common but virtually undetectable. The issue I have with non-baryonic dark matter, and I’ve been into this before on here, is that it seems to be a specially invented kind of matter to fill the gap in the model which, however, is practically undetectable. There’s another possible solution. What makes this worse is that dark matter is now being used to argue for flaws in the general theory of relativity, when it seems very clear that the problem is actually that physicists have proposed the existence of a kind of substance which is basically magic.

If you go back to the first moment of the Universe, there is a similar issue. Just after the grand unification epoch, a sextillionth (long scale) of a second after the Big Bang, an event is supposed to have taken place which increased each of the three extensive dimensions of the Universe by a factor of the order of one hundred quintillion in a millionth of a yoctosecond. If you don’t recognise these words, the reason is that these are unusually large and small quantities, so their values aren’t that important. Some physicists think this is fishy, because again something seems to have been simply invented to account for what happened in those circumstances without there being other reasons for supposing it to be so. They therefore decided to see what would happen if they used established principles to recreate the early Universe, and in particular they focussed on CPT symmetry

CPT symmetry is Charge, Parity and Temporal symmetry, and can be explained thus, starting with time. Imagine a video of two billiard balls hitting and bouncing off each other out of context. It would be difficult to tell whether that video was being played forwards or backwards. This works well on a small scale, perhaps with two neutrons colliding at about the speed of sound at an angle to each other, or a laser beam reflecting off a mirror. Charge symmetry means that if you observe two equally positively and negatively charged objects interacting, you could swap the charges and still observe the same thing, or for that matter two objects with the same charge could have the opposite charges and still do the same thing. Finally, parity symmetry is the fact that you can’t tell whether what you’re seeing is the right way up or upside down, or reflected. All of these things don’t work in the complicated situations we tend to observe because of pesky things like gravity and accidentally burning things out by sticking batteries in the wrong way round or miswiring plugs, but in sufficiently simple situations all of these things are symmetrical.

But there is a problem. The Universe as a whole doesn’t seem to obey these laws of symmetry. For instance, almost everything we come across seems to be made of matter even though there doesn’t seem to be any reason why there should be more matter than antimatter or the other way round, and time tends to go forwards rather than backwards on the whole. One attempt to explain why matter seems to dominate the Universe is that for some reason in the early Universe more matter was created than antimatter, and since matter meeting antimatter annihilates both, matter is all that’s left. Of course antimatter does crop up from time to time, for instance in bananas and thunderstorms, but it doesn’t last long because it pretty soon comes across an antiparticle in the form of, say, an electron, and the two wipe each other off the map in a burst of energy.

These physicists proposed a solution which does respect this symmetry and allows time to move both forwards and backwards. They propose that the Big Bang created not one but two universes, one where time runs forwards and mainly made of matter and the other where time goes backwards and is mainly made of antimatter, and also either of these universes is geometrically speaking a reflection of the other, such as all the left-handed people in one being right-handed in the other. This explains away the supposèd excess of matter. There’s actually just as much antimatter as matter, but it swapped over at the Big Bang. Before the Big Bang, time was running backwards and the Universe was collapsing.

In a manner rather similar to the thought that an oscillating Universe could be practically the same as time running in a circle because each cycle might be identical and there’s no outside to see it from, the reversed, mirror image antimatter Universe is simply this one running backwards with, again, nothing on the outside to observe it with, and therefore for all intents and purposes there just is this one Universe running forwards after the Big Bang, because it’s indistinguishable from the antimatter one running backwards. On the other hand, the time dimension involved is the same as this one, and therefore it could just be seen as the distant past, which answers the question of what there was before the Big Bang: there was another universe, or rather there was this universe. It also means everything has already happened.

But a further question arises in my head too, and this is by no means what these physicists are claiming. As mentioned above, one model of the Universe is that it repeats itself in a cycle. What we may have here is theoretical support for the idea of a Universe collapsing in on itself before expanding again. That’s the bit we can see or deduce given currently available evidence. However, in the future, certain evidence will be lost because there will only be one visible galaxy observable, and the idea of space expanding will be impossible to support even though it is. What if one of the bits of evidence we’ve already lost is of time looping? Or, what if time just does loop anyway? What if time runs forwards until the Universe reaches a maximum size and then runs backwards again as it contracts? There is an issue with this. There isn’t enough mass in the Universe for it to collapse given the strength of dark energy pushing it apart, but of course elsewhere in the Multiverse there could be looping universes due to different physical constants such as the strength of dark energy or the increased quantity of matter in them, because in fact as has been mentioned before there are possible worlds where this does take place. Another question then arises: how does time work between universes? Are these looping universes doing so now in endless cycles, or are they repeating the same stretch of time? Does time even work that way in the Multiverse, or is it like in Narnia, where time runs at different speeds relative to our world?

It may seem like I’ve become highly speculative. In my defence, I’d say this. I have taken pains to ignore my intuition in the past because I believed it was misleading. However, there appears to be an intuition among many cultures that time does run in a cycle, and the numbers these cultures produce are oddly similar. The Mayan calendar’s longest time period is the Alautun, which lasts 63 081 429 years, close to the number of years it’s been since the Chicxulub Impact, which coincidentally was nearby and wiped out the non-avian dinosaurs. The Indian kalpa is 4 320 million years in length, which is again quite close to the age of this planet. Earth is 4 543 million years old and the Cretaceous ended 66 million years ago, so these figures are 4.6% out in the case of the Maya and 5% for the kalpa. Of course it may be coincidence, and the idea of time being cyclical may simply be based on something like the cycle of the day and night or the seasons through the year, but since I believe intuitive truths are available in Torah and the rest of the Tanakh, I don’t necessarily have a problem with other sources. Parallels have of course been made between ancient philosophies and today’s physics before, for example by Fritjof Capra in his ‘The Tao [sic] Of Physics’. Although much of what he says has been rubbished by physicists since, there is a statue of Dancing Shiva in the lobby at CERN and one quote from Capra is widely accepted:

“Science does not need mysticism and mysticism does not need science. But man needs both.”