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Life, the Universe and Everything...
Latest update 22 January 2013 - the Huge-LQG - see bottom of page
In The Diary of a Wandering Mind, I’ve had several tries at what I’ve come to call my non-counterintuitive explanation of how we got from the Big Bang to where we are today. The most recent writings were Religion and science and the the latest edit of Groping towards quantum physics, where I was finding myself reasonably comfortable with the structure of the atomic nucleus - I thought.
Then what I’ve been trying to do - to compile an explanation that marries reasonably comfortably with our everyday experience of the world around us - ran up against the buffers.
To avoid dying of boredom during my five-mornings-a-week walks, I’ve been quietly muttering sort-of standup routines to an imaginary audience. I find that I can do this without embarrassment on the secluded lane I use, keeping my voice down and my lips more-or-less stationary - I can always start singing if I’m caught unawares! Anyway, having got a bit bored with slagging off the current dismal crop of politicians and rowing with recalcitrant family members, I recently switched to ’Life, the Universe and Everything’, to quote the much loved and missed Douglas Adams. There are less opportunities for ad lib jokes than in politics, but since my audience is imaginary that doesn’t matter too much.
Anyway, there I was, reasonably comfortable with the knowledge that every atom consists of almost nothing but hard vacuum, that atomic nuclei are made of protons and (except in the case of hydrogen) neutrons, and that protons and neutrons are both made of up quarks and down quarks. Then I decided to do some reading that would help me understand how so much mass (which we experience as weight) can be concentrated into something as minute as the nucleus. Back to Wikipedia - and straight into a black hole!
I’d searched for ’mass of proton’ and hit a total dead end. This is what I found...
Mass and energy are, I knew, to some extent interchangeable. We release energy when we disrupt the structure of matter by anything as easy as burning or as difficult as nuclear fission. I’d been struggling with how the process could be reversed, turning energy back into mass, though. But the energy of massless particles (and I still struggle with things like gluons and even photons) being measured as mass...? Help!
It gets worse. I had assumed that the term ’rest mass’, used four times in the paragraph quoted above, was the bit of the mass of the proton that wasn’t due to the energy. However, on searching for ’rest mass’...
This leads to the inescapable conclusion that there is absolutely nothing really solid (in the sense that our intuition understands the word) in the entire Universe! Not even atomic nuclei. Everything, it seems, is ’made of’ energy - provided you dig deeply enough into the quantum world inside the atom.
Which means that my quest for a ’non-counterintuitive explanation of how we got from the Big Bang to where we are today’ stops dead when it hits the electron shell of the atom. Everything inside that tiny bubble of just-about-bugger-all is, as Prof Jim has said, weird.
So there I am, walking along the lane, the heels of my battered Reeboks banging down on the tatty tarmac (it isn’t a public road, though there’s plenty of tatty tarmac on the public ones in our deprived north!) and enjoying the sights of the sky, the distant view, the trees and the hedgerows, relishing the sounds of the birds and of my own voice as I chunter on to my imaginary audience, sucking in the fresh country air - and basically nothing is what it seems. The rubber heels, the tarmac, the images seen by my eyes, the sounds, the temperature of the air? All some kind of illusion.
The outer electrons of atoms in the rubber and the tarmac are bouncing off the mutual repulsion of each other’s negative electrical charges and transmitting some of the energy to the atoms of my skin inside the trainers. The light - which my eyes capture (or don’t) and my brain processes - has been reflected, refracted, transmitted or absorbed by those same electrons. The temperature of the air is a measure of the energy of the atoms of which it consists, presumably slowing down the motion of more electrons in the atoms of my nasal membranes by stealing energy from them. All this interaction between atoms is being translated into electrical signals (electrons skipping from atom to atom - or is that an obsolete model of electric current?) in my various nerves , which are interpreted by atoms in my brain to produce the images and sensations I think I am experiencing.
And do you know what the really clever bit is? That when I touch what I see, the tactile information and the visual information correspond perfectly to produce a complete and coherent map of what I’m feeling and looking at. And the whole amazing process involves nothing more than up quarks, down quarks and electrons (let’s ignore the massless ’mediating’ entities like gluons for now!) which must have been doing their things since the Big Bang itself. I and my surroundings consist entirely of tiny components which are at least 13,700,000,000 years old, and they still haven’t worn out. (I say ’at least’ because not even our cleverest physicists seem to have explained how every one of those truly indivisible components happened to be in the unimaginably dense singularity from which the Big Bang kicked off the development of our marvellous universe.)
Mass and energy
If you look up ’mass of proton’ in Wikipedia, you get a choice of three values:
I don’t know what the values in brackets after the decimal numbers mean, but kilograms (kg) are easy - the SI unit of mass and weight which I use in the kitchen almost every day. The ’x10−27’ bit makes for pretty unwieldy numbers, though: that’s the number one with a decimal point and no less than 27 zeroes before it. So I guess that’s why the other two units are preferred.
The ’u’ stands for the ’unified atomic mass unit’ or dalton - defined as ’one twelfth of the rest mass of an unbound neutral atom of carbon-12 in its nuclear and electronic ground state’ with a value of 1.660538921(73)×10−27 kg.
The one that’s been doing my head in, and which which seems to be the favoured unit of mass among particle physicists, is the electonvolt (eV). It is defined as ’the amount of energy gained by the charge of a single electron moved across an electric potential difference of one volt’. So it’s a unit of energy rather than of mass. Except, of course, we seem to have got to the point a few paragraphs back where mass and energy are more-or-less the same thing!
The MeV is a million electronvolts, but the weird bit is the ’/c2’, which means ’divided by the speed of light squared’.
I had a chat about this with my imaginary audience on one of my walks, on the basis that explaining something to someone else (even someone else imaginary) is the best way to get to understand it yourself! And I came to two separate conclusions.
First the simple arithmetic. The speed of light is 299,792,458 metres per second (the metre being the SI unit of length), but is normally approximated to 300,000 kilometres per second - or 186,000 miles per second if you’re still wedded to obsolete imperial units. So c2 is the square of the speed of light - presumably in metres rather than kilometres per second. So, sticking with the basic SI units (metre, kilogram and second), so I guess c is roughly 300,000,000 and c2 is roughly 90,000,000,000,000,000, so using the eV/c2 as a unit, which seems a pretty weird thing to do, looks just as clumsy as using the kilometre. Using the unit MeV/c2 (the mega-electronvolt divided by 90,000,000,000,000,000), we are expressing the mass of particles in millions of ninety-quadrillionths of an electronvolt (I think - these loony numbers are pretty hard to deal with!).
Second, the Einstein bit. We are all (I hope) familiar with the great man’s famous equation describing the relationship between mass and energy: E = mc2. And even I, with my very-bare-pass in O-level maths in 1959 and my especially-vague recollections of the algebra component, can - after scraping around at the bottom of my mathematical barrel - swivel that round to m = E/c2. That gives us the form of the superficially odd unit: mass = E eV/c2, the capital ’E’ being the value of the energy term in Einstein’s magic equation.
My head continues to be done in. Using a ludicrously tiny fraction of a kilogram is unwieldy, but at least the friendly kilo is a unit of mass. Putting a formula in the name of the unit to convert energy to mass just seems barmy. But...isn’t expressing velocity in miles divided by hours just the same thing? We used to express the frequency of a wave in cycles per second (c/s), too, until we were rescued by by the invention of the hertz...
I’m going round in circles now - probably ever-decreasing ones, and we all know where those send us! So maybe it’s time to get back to what I was doing before I went off on this mass-and-energy thing...
Back on track (or not)...
I suppose it’s not surprising that this mass/energy thing is a bit tricky. After all, particle physicists still seem to be groping towards an explanation of why matter has mass at all. The quest for the Higgs boson seems to be evidence of that! This is the Holy Grail for many physicists working with the Large Hadron Collider at CERN, decribed by Wikipedia as ’a hypothetical elementary particle predicted by the Standard Model of particle physics...which...explains why other elementary particles have mass...the only elementary particle predicted by the Standard Model that has not yet been observed in particle physics experiments’.
I assume that the masses of the up and down quarks and the electron (aided, or not, by the Higgs boson) are what gives atoms, and therefore our own friendly everyday matter, its mass, so unless the Higgs is found even my 14-stone weight will be beyond scientific explanation! We are told that success (or not) is expected by the end of 2012, so not long to wait...
In the course of writing this, I did a quick scan through parts of Why Does E = mc2, by Brian Cox and found a pretty profound remark about the weirdness of the quantum world. Unfortunately I lost this quote, but essentially what it seemed to be asking is: why should we expect things in the sub-atomic world to behave in similar ways to those in our macroscopic world? That seems to confirm that my quest for a non-counterintuitive explanation of life, the universe and everything should stop at the outer electrons of the atoms. It doesn’t stop me being quite fascinated by all this strange stuff, though...
So, difficult as it is to believe, I seem to be stuck with the conclusion that much of the mass of matter is concentrated in the tiny nuclei of its relatively large atoms.
Back to the Big Bang
So, where did all this matter come from? The key is a process called nucleosynthesis, which means just what it says: the synthesis of atomic nuclei. Back to Wikipedia, to which I haven’t provided links as it would be just too laborious - just go to the site and search for anything I write that needs clarification, but I’ll make an exception here: the general article on nucleosynthesis is the source of what follows.
It seems that the first product of the Big Bang was a plasma of quarks and gluons (glue-ons - remember?). (A plasma, Wikipedia told me, is similar to a gas, but one normally containing atoms or molecules that have lost or gained electrons and are therefore positively or negatively charged. As up and down quarks have opposite charges, I supposed a ’soup’ of separate ones is bound to be a plasma...?) As this ’cooled’ below two trillion degrees (I’ve commented elsewhere about this curious use of the verb ’to cool’!), the primordial nucleons (protons and neutrons, the components of all nuclei) were formed as the up and down quarks were brought together by the strong force mediated by the gluons. This process was followed within a few minutes by the formation of nuclei of the first (and lightest) four elements in the periodic table: hydrogen (by far the most plentiful and, as I understand it, the one created only in the Big Bang), helium, lithium and beryllium (only small quantities of these three, the rest of what we find today being created much later). The next two, boron and carbon may have started to form, but this Big Bang fusion process, or Big Bang nucleosynthesis, was ended by the drops in termperature and density as the infant universe expanded.
There was then a pause of about 500 million years, or between 3% and 4% of the total life of the universe up to the present, while hydrogen and helium, aided by their tiny gravitational attraction, condensed into the first heavy stars. Then, in the improbably dense hearts of these early stars the nuclear fusion reaction re-started, forming elements 6 (carbon) to 26 (iron) in what is known as stellar nucleosynthesis. (’Stars are the nuclear furnaces in which H[ydrogen] and He[lium] are fused into heavier nuclei, a process which occurs...in stars cooler than the Sun, and...in stars more massive than the Sun.’)
So where did elements 27 (cobalt) to 98 (californium) - the heaviest naturally occurring element - come from?
The answer is from explosive nucleosynthesis, which happens only when a star’s life ends in a supernova. This doesn’t happen to all stars, but those that do die in this spectacular way undergo a brief but powerful series of nuclear reactions - mainly more fusion - that can produce all the heavier naturally occurring elements. These are scattered across space, forming arguably the most beautiful things in the universe: nebulae. Go to the Wikipedia page for a glimpse of some of these amazing sights, and to the Hubble Space Telesope site for many more stunning images. Nebulae are where new stars and, it is believed, their planetary systems form from the abundant supplies of elements.
And that, in brief, is how our solar system came to be formed and to contain significant quantities of all 98 naturally-occurring elements. All that in just 13.7 billion years from a searingly-hot soup of nothing more than quarks and gluons!
Space and time
All that seems reasonably straightforward to me, in the ignorance that allows me to ignore the subtleties of physics. However, if we start asking questions like ’What was there before the big bang?’ we get back into serious trouble.
Of space, Wikipedia says: ’Relativity theory...’ Uh-oh - Einstein again! ’...leads to the cosmological question of what shape the universe is, and where space came from. It appears that space was created in the Big Bang, 13.7 billion years ago and has been expanding ever since. The overall shape of space is not known, but space is known to be expanding very rapidly due to the Cosmic Inflation.’
Of time, Wikipedia says: ’Hawking has stated that time actually began with the Big Bang, and that questions about what happened before the Big Bang are meaningless.’
I’ve been bouncing around the ideas that space ’was created’ and ’is known to be expanding’, and that time ’began’ with the Big Bang on my morning walks for quite a while, and I’m afraid it just doesn’t help with my search for a non-counterintuitive explanation of how we got from the Big Bang to where we are today.
If space wasn’t there until the Big Bang, what was there? Without space, where and how did the Big Bang happen? If there was no before the Big Bang, what made it happen?
For me, space is the absolute absence of anything at all - it isn’t any kind of stuff. I know the space occupied by our universe is full of matter and energy, but that universe (according to Big Bang theory) started out infinitesimally small (the singularity) and has grown into something almost unimaginably vast. If space is finite, and is growing with the universe, what is it growing into, if not more space? Again, if space is finite it must have an edge, and I can’t help asking what we would find if we travelled to that edge and then tried to keep going.
The idea that time wasn’t there before the Big Bang makes slightly more sense, but only if we accept that there was nothing happening - nothing changing - before the Bang. I once heard time defined as something like ’the measurement of change’, so if nothing was changing there was nothing to measure and therefore no time. Without space and something occupying it and changing, the very idea of time is meaningless.
So, back to space...
If space only came into existence (if nothing can be said to exist) with the Big Bang, and was suddenly occupied by a vast quantity of matter and energy, where did that matter and energy come from? The idea that it suddenly and mysteriously popped into existence out of nowhere and rapidly developed into a cloud of subatomic particles (presumably all the particles that make up today’s universe) at a temperature more than two trillion (2,000,000,000,000) degrees makes about as much sense as the belief that an incredibly powerful entity somehow existing outside space itself (let’s call it ’God’, for want of a better name) snapped its fingers (if it had fingers) and called the matter and energy into existence by an act of pure will. Either way, if the universe did appear out of absolutely nothing at all, most of us would probably be happier accepting God - at least the story is a bit more poetic!
I have immense respect for Professor Hawking, but I have to say that ’time actually began with the Big Bang, and...questions about what happened before the Big Bang are meaningless’ seems to me to be a total cop-out and, in the absence of evidence from before the Big Bang, to be a totally unwarranted assumption rather than a respectable scientific theory.
Just because there is no evidence of anything existing before the Big Bang doesn’t mean that nothing did exist. If the Bang was the kind of cataclysmic event we assume it to have been, you’d expect it to have obliterated all evidence of anything existing before that time, but that doesn’t mean that the evidence was never there. Surely the truly scientific response to the absence of evidence is the time-honoured ’we don’t know - yet’ - not the dogmatic statement quoted above. And just because the mathematicians and theoretical physicists can’t see an alternative to that statement doesn’t make it true. They’re only human, after all.
Hawking’s conclusion is a statement of what he has chosen to believe, as are the many other creation myths that man has dreamed up through the millennia.
People seem to have a big problem accepting that things have always been the way they are. They have a profound need to ask how things got that way. My suggestion below that the quarks were always around triggers the automatic question ’Yes - but how did they get there?’
Why did they have to ’get there’? Why shouldn’t they just always have been there? That seems to me far more likely than any alternative scenario, scientific or theological.
So what, for a simple soul like me for whom advanced mathematics is a closed book but for whom the idea of a god is anathema, is the alternative to current scientific orthodoxy?
Something I can actually believe...
I still like the idea of the ’oscillating universe’, about which I first read in an article by the great science-fiction writer Isaac Asimov in the early 1960s. Unlike the two ’creation theories’ (the scientific one and the religious one outlined above), this at least seems to obey the laws of the conservation of matter and energy.
My version of this assumes that space is infinite and has always ’been there’ (or not, because pure space probably isn’t really ’there’ at all). The matter and energy that constitute the current universe have also always existed, though in many changing forms, from an insanely hot soup of detached quarks and gluons to the glorious structure we see today. Always there - why? Because if they are there now but haven’t always been there, where the hell did they come from?
As I’ve attempted to understand in the previous sections, matter (or mass) and energy are interchangeable - but the total of the two is conserved. What we know in our everyday world as matter was assembled from various sub-units - from molecules that were built from atoms, which in turn were built from wandering nuclei teaming up with drifting electrons. The nuclei were in turn built from protons and (usually) neutrons, and these are both ’made’ of quarks. The general belief is that quarks aren’t made of anything: they are genuinely fundamental, the only components of matter which can’t be further dismantled.
Given that the Standard Model describes an immensely hot plasma containing only quarks and gluons (see above), it seems safe to assume that quarks are uniquely indestructible. After all, you can’t dismantle something that isn’t assembled from smaller somethingss, and conservation says you can’t annihilate mass or energy completely. To borrow Hawking’s word, the idea of destroying quarks is ’meaningless’.
So all the quarks in all the atoms in the universe must have been around, either free or tied up in protons and neutrons, since the Big Bang.
So the quarks in the primordial plasma, assisted by the gluons, joined up to form protons and neutrons, and from these the first atoms were formed. These ’fell’ together to form stars, and in the nuclear furnaces of the earliest, largest and shortest-lived stars all the lighter elements were formed. As part of the expanding universe, these stars in turn exploded, and in the new nuclear furnaces of these supernova explosions all the heavier elements were formed and scattered generously around the local space. Here, in nebulae, new stars formed from the naturally-occurring elements. Because all those elements were scattered by the explosions, they were available not only for stars but also for planets and moons and asteroids and meteorites.
So far, so good. Now, whatever the effects of dark matter and dark energy, we have to assume that the expansion of the universe will run out of steam eventually.
Bodies in orbit around heavier bodies (moons around planets, planets around suns and suns around the super-massive black holes at the centres of their galaxies) are actually falling towards the bodies they orbit. Falling but missing - like Douglas Adams’s wonderful instructions on how to fly: just throw yourself at the ground and miss! However, orbits decay and it must be the ultimate fate of every orbiting body to collide with the body it orbits. Eventually, all the matter in each galaxy will become part of that galaxy’s supermassive black hole.
What happens ’inside’ a black hole is a mystery, because no useful information escapes the hole’s enormous gravity (I put quotation marks around ’inside’ because black holes must actually be very solid indeed - not holes at all), but it doesn’t seem unreasonable to suggest that the vast forces at work might actually dismantle all matter into a dense mass of quarks. In fact, I’ve just found precisely this idea in Brian Cox’s Wonders of the Universe: He suggests that the core of a black hole may be the same super-hot quark-gluon plasma that existed immediately after the Big Bang.
So, as the momentum of the expanding universe runs down, we can imagine all these super-massive, ultra-massive, hyper-massive or whatever black holes coming to a standstill (relative to one another, because there can be no absolute positions in space) and beginning to fall together. Would it take all of them to combine to create a new Big Bang? Or just those closest to the centre-of-gravity of the universe? I’ll leave that one to the equation-geniuses. However, at some point there would be a mass of crushed-together quarks and gluons so stressed and so unstable that this grand-daddy of all black holes would blow its top. Inflation would begin again, possibly hoovering-up the black holes that hadn’t actually got to the centre before all hell (or heaven) broke loose, and the evolution of a new universe would begin.
I may be very very wrong. But probably not as wrong as the proponents of my ’two creation theories’. For the moment, infinite space and the eternal oscillating universe does it for me.
Anybody want to argue? I do hope so! Just click the Contact me button on the right...
Having invited the world to debate what I’ve written, I had a sudden urge to look at my copy of Hawking’s A Brief History of Time, now almost a quarter of a century old. I’ve been taking notes, with page-numbers, on anything particularly relevant to my quest, and up to page 50 - where we depart from relativity into the realm of quantum mechanics - I feel that I’ve held my own reasonably well. And that my oscillating-universe model hasn’t been totally squashed!
Unless I have totally misunderstood what I’ve read so far, the only firm argument for time having begun with the Big Bang seems to be the absolute impossibility of seeing any evidence from before that event. We can’t see events before the Bang so we have to assume that there weren’t any. But you can’t prove a negative...
’...even if there were events before the big bang, one could not use them to determine what would happen afterward, because predictability would break down at the big bang. Correspondingly, if, as is the case, we know only what has happened since the big bang, we could not determine what what happened beforehand. As far as we are concerned, events before the big bang can have no consequences, so they should not form part of a scientific model of the universe. We should therefore cut them out of the model and say that time had a beginning at the big bang.’
Unlike the earlier quotation, this isn’t a clear and dogmatic statement of fact. Rather, it is just an honest scientist/mathematician accepting the limitations imposed on his model by the absence of evidence. However, ’events before the big bang can have no consequences’ grates. Surely some of these must have had the most collossal set of consequences of all time: the Big Bang itself and what has followed since!
Fine. I’m neither a scientist nor a mathematician, and I’m not trying to build a scientific theory. I just want to know that, in spite of the best available information, it’s possible that my proposal - which is ultimately about me feeling a bit more comfortable - has some validity.
Meanwhile, a few tasty morsels from the first fifty pages...
’As we shall see, the concept of time has no meaning before the beginning of the universe. This was first pointed out by St Augustine...he said that time was a property of the universe that God created, and that time did not exist before the beginning of the universe.’ A man before his time, Augustine! But it all depends on what you mean by ’the beginning of the universe’: in my model, there was no beginning, and the Big Bang was just one of possibly many presses of the reset button.
’A [scientific] theory is just a model of the universe, or a restricted part of it, a set of rules that relate quantities in the model to observations that we make. It exists only in our minds and does not have any other reality (whatever that might mean).’
’Any physical theory is always provisional, in the sense that it is only a hypothesis: you can never prove it. On the other hand you can disprove a theory by finding even a single observation that disagrees with the predictions of the theory.’
’Today scientists describe the universe in terms of two basic partial theories - the general theory of relativity and quantum mechanics...relativity describes the force of gravity and the large-scale structure of the universe...on scales from only a few miles to...a million million million million...the size of the observable universe. Quantum mechanics...deals with phenomena on extremely small scales such as a millionth of a millionth of an inch. Unfortunately...these two theories...cannot both be correct.’
Yet relativity has given us nuclear energy and quantum mechanics has given us microelectronics...
’Perhaps the best known [consequences of the theory of relativity] are the equivalence of mass and energy, summed up in Einstein’s famous equation E = mc2...and the law that nothing may travel faster than the speed of light. Because of the equivalence of energy and mass, the energy which an object has due to its motion will add to its mass...it will make it harder to increase its speed...at 10 percent of the speed of light an object’s mass is only 0.5 percent more than normal, while at 90 percent of the speed of light it would be more than twice its normal mass.As an object approaches the speed of light, its mass rises ever more quickly, so it takes more and more energy to speed it up further. It can in fact never reach the speed of light, because by then its mass would have become infinite, and...it would have taken an infinite amount of energy to get it there...only light, or other waves that have no intrinsic mass, can move at the speed of light.’
’If [the universe] was expanding fairly slowly, the force of gravity would cause it eventually to stop expanding and then to start contracting.’ So far, so good! ’However, if it was expanding at more than a certain critical rate, gravity would never be able to stop it.’ Uh-oh... ’If [a rocket fired upwards from the surface of the earth] has a fairly low speed, gravity will eventually stop [it] and it will start falling back...if [it] has more than a certain critical speed (about seven miles per second) gravity will not be strong enough to pull it back.’
’When we add up all this dark matter, we...get only about one tenth of the amount required to halt the expansion. However, we cannot exclude the possibility that there might be some other form of matter, distributed almost uniformly throughout the universe, that we have not yet detected and that might still raise the average density of the universe up to the critical value needed to halt its expansion.’ There’s hope for me yet...
But not much when it comes to quantum mechanics! Every time I’ve read Hawking’s famous book I’ve felt I was getting further through it before it got too difficult. I’d got as far as page 70, where the explanations of the ’forces of nature’ begin - that’s the gravitational force (the one that holds galaxies and stars - and us - together), the electromagnetic force (which, among other things, holds nuclei and electrons together to form atoms), the weak nuclear force (which got very complicated, and was only given credit for being ’responsible for radioactivity) and the strong nuclear force (which holds quarks together to form protons and neutrons, and protons and neutrons together to form atomic nuclei). Then we got into the ’colours’ and spin of quarks, and our first serious encounter with antimatter particles. Too much for my ageing brain, I’m afraid. A bit of skipping was necessary...
The two chapters on black holes were largely skipped - too much relativity. Then came the chapter entitled The Origin and Fate of the Universe - just what I’ve been hammering on about here. The ’big crunch singularity’, the result of the whole universe recollapsing, was acknowledged as a possibility in Einsteins general theory of relativity. His assertion that space-time (which had begun at the Big Bang singularity) would end at the big crunch singularity. Or, and this is where it gets iffy, ’at a singularity inside a black hole (if a local region, such as a star, were to collapse’. Is that all the space-time in the universe, or just some local space-time.
I haven’t mentioned space-time here, preferring to stick to my separate and doubtless simplistic concepts of separate space and time. I can’t accept the idea of gravity being due to the curvature of space (and anyway, isn’t it supposed to be caused by the exchange of force-carrying particles between atoms?), but I can’t argue against the curvature of space-time because I don’t really understand what it is.
I’m going to try and stick at my reading, but for the moment I seem to be presented with a choice between three possible accounts of our universe.
The three creation myths
The first is the scientific one, in which I thought Hawking was stating categorically that space and time were created out of nothing at the Big Bang. Only when I started reading his book did I realise that it is actually the only credible scientific account, based of what is known or can be inferred from the evidence. It boils down to ’we don’t know’, because any evidence that might have existed before the Big Bang was annihilated by the Bang itself. So science has to work on the basis that there was no ’before the Big Bang’, while remaining open to the possibility of new evidence emerging in the future.
The second is the religious one, in which everything in the universe was conjured into being by an entity existing outside space and time - God, if you like. For me, this is just too anthropocentric. I mean...God creating man in his own image is just human vanity gone mad, and I believe that the exact reverse is true. Man created God in his own image.
The third is my willingness to accept that the mass and energy that make up today’s universe have always existed, though in a constantly-changing balance, and will continue to exist forever. Why not? It’s only quarks and stuff! So...Big Bang...Big Crunch...Big Bang...Big Crunch - ad infinitum. No miraculous creation of this awesome store of stuff, by either chance or God. Just a constantly changing arrangement of a vast but finite store of fundamental particles. So this is really me accepting the scientific position but thinking about what might have been around before the Big Bang - and caused it. I’m sure scientists must do this too, perhaps over a few pints at the end of a long day.
The shape of things
Somewhere in A Brief History of Time, Hawking uses the analogy of an inflating balloon to explain how all bodies in the universe - or at least the galaxies - are moving further apart. Curious about this, I looked up the shape of the universe on Wikipedia and promptly found myself lost in a mass of relativity stuff, including various models of curved space.
I’d never thought much about this, but the balloon idea makes sense. If, indeed, the universe (or this universe) did begin with everything crammed into a tiny - even infinitesimal - lump of particles, all of which were hurled outwards by a single huge application of force - the Big Bang - then it follows that, rather than a cloud of gas, there would be a spherical shell. The universe must in fact be hollow: empty space (my kind of space - not Einstein’s) contained by a thin layer of scattered bits of matter. So, if we look out from the Earth, we might be looking tangentially along the shell, outwards beyond it or into it, possibly looking right across to the opposite side and beyond.
In the first case, we would be seeing the stuff close to us, but presumably our line-of-sight would eventually go off into the empty space outside the shell. In the second, we would only see the stuff in our part of the shell and would find empty space much closer. In the third, we would see the close stuff, then a lot of empty space, and then stuff on the opposite side of the shell, a long way away.
Recently I started having a second go at Why does E = mc2 by Brian Cox and Jeff Forshaw, and then discovered from The Observer that the pair have published another book, The Quantum Universe. I’ve just downloaded this to my Kindle.
I’d been fitting short bursts of the first book between other (more relaxing) reading, but found that this didn’t work. I’d get into a new topic and find that the references back to previous chapters didn’t ring any bells at all. Clearly an alternative strategy was needed, so I started again in the same way as with the Hawking book: reading and taking notes of all key points. I didn’t keep up the note-taking, though I did finish the book this time. It’s an interesting read, and quite entertainingly written, but I don’t feel much the wiser!
Since relativistic effects only seem to come into play when things are moving very fast, which in this context means at a significant fraction of the speed of light, they don’t have much effect on the everyday world we inhabit. In fact, the only things that move fast enough for relativity to come into calculations are rays and particles. The effects have to be taken into account in satellite navigation systems and other highly sophisticated technologies, but we can still send space probes to Mars and far beyond without taking them into account.
Meanwhile, on my morning walks I continue to talk to my imaginary audience about this stuff - and continue to be in a bit of a tangle with it. It’s to do with the theories that there is no such thing as absolute space and no such thing as absolute time. Position, motion and velocity are all relative (as you might expect in a theory of relativity!), and I think I can handle that because it ties in nicely with my belief that space is an infinite amount of nothing. The time thing is more difficult: if time moves more slowly or quickly (can’t remember which) than on earth in a spaceship travelling at just-sublight speed relative to earth, who or what chooses which object (ship or earth) is moving and which is stationary? And if all motion is relative and time is elastic, how can the speed of light be an absolute value?
Update 8 November 2012: solidity and neutron stars
My brain took quite a long holiday from all this stuff recently, but I’ve been catching up with all the science documentaries on my FreeSat hard drive and a couple of other things have cropped up.
One is the notion of solidity. If the atoms, molecules and materials we perceive as solid - all too solid if we bump into them, or they into us! - turn out to be nothing of the sort, why should be assume that protons, neutrons and quarks are any more solid? We know that protons and neutrons are built from quarks, but that doesn’t necessarily mean that - as I’ve vaguely assumed until now - the protons and neutrons in atomic nuclei, or the quarks that make them up, are tightly stuck together like bits of a Chinese wood-block puzzle - that might be taking the ’glu’ in ’gluon’ a bit too literally! They might be whizzing around one another but unable to escape the strong force that binds them. Equally, although the best theory says that the quarks are fundamental, that doesn’t necessarily mean that they are single, solid entities. Again, they could be clusters of separate but inseparably captive ’bits’. We are in the quantum world, after all, and even the physicists happily tell us that stuff at that level is very weird. If the word ’solid’ turns out to be meaningless in terms of the atoms that make up us and everything around us, why on earth should it mean anything for even smaller things?
A quick glance back up this page yielded the following: ’The rest mass of the proton is, thus, the invariant mass of the system of moving [my highlight] quarks and gluons that make up the particle [proton]’, which seems to confirm that the quarks that make up a proton really are leaping around rather than stuck tightly together.
Another matter came to my attention while watching the BBC’s recent The Seven Ages of Starlight which, towards the end, talked about neutron stars. These are the improbably dense end-products of the deaths of very large stars, produced when a supernova has blown much of their substance off into space, leaving only the core, and all the other forces have to surrender to gravity. Even larger stars are believed to end as black holes (see below). It seems that, as the substance of these stars is crushed together by its own monstrous mass, the atoms themselves break down. The electrons are stripped off to leave free nuclei, and the protons turn into neutrons. These have no electric charge to resist being crammed tightly together, so the result is all the mass of the core squeezed into the smallest possible volume.
And that means seriously small.
Wikipedia says (stripping out some confusing technical stuff): ’A typical neutron star has a mass between about 1.4 and 3.2 solar masses [the mass of our sun], with a corresponding radius of about 12 km...This density is approximately equivalent to the mass of a Boeing 747 compressed to the size of a small grain of sand, or the human population [of planet Earth] condensed to the size of a sugar cube.’ I’ve mentioned the sugar cube analogy elsewhere, but the jumbo-jet one was new to me.
Wikipedia goes on...
’In general, compact stars of less than 1.44 solar masses...are white dwarfs, and above 2 to 3 solar masses...a quark star might be created; however, this is uncertain. Gravitational collapse will usually occur on any compact star between 10 and 25 solar masses and produce a black hole.’
’A quark star or strange star is a hypothetical type of exotic star composed of quark matter, or strange matter. These are ultra-dense phases of degenerate matter theorized to form inside particularly massive neutron stars.’
There’s a bonus paragraph immediately following this one - a possible clue to the nature of dark matter: ’It is theorized that when the neutron-degenerate matter which makes up a neutron star is put under sufficient pressure due to the star’s gravity, the individual neutrons break down into their constituent quarks – up quarks and down quarks. Some of these quarks may then become strange quarks and form strange matter...Quark matter/strange matter is one candidate for the theoretical dark matter that is a feature of several cosmological theories.’ This would certainly explain why dark matter doesn’t radiate light or other detectable radiation.
It looks as if my wild guesses above about what might happen to the matter in a collapsing universe weren’t too far wide of the mark after all. I feel good!
And on this high note I can only recommend that you go to Wikipedia’s page on neutron stars and follow whatever links take your fancy...
Except to back-track briefly on the subject of protons turning into neutrons, which I haven’t mentioned but which is essential to the development of a neutron star, since all the atoms except hydrogen-1 contain protons, electrons and neutrons. The following little clip from Wikipedia seems to shed light on this, establishing that protons can be turned into neutrons with the aid of electrons:
’However, protons are known to transform into neutrons through the process of electron capture...For free protons, this process does not occur spontaneously but only when energy is supplied.’ I think we can safely assume that the gravitational collapse of a massive star’s core following a supernova explosion would supply more than enough energy!
This page doesn’t even mention quarks, despite the fact that a proton consists of two up quarks and a down quark, whereas a neutron consists of two down quarks and a up quark. However, it does say that the process involves the emission of a neutrino followed by ’various photon emissions’. My untutored mind takes comfort from the suggestion that a positively charged proton can be converted into a neutral neutron by the capture of a negatively charged electron - in the midst of all this other stuff that seems quite simple and logical!
And I have read somewhere else that the deaths of even more massive stars than those that give birth to neutron stars, and possibly quark stars, end life as the most massive objects of all: black holes. These are presumably composed of quarks, which are assumed to be indivisible, squashed together even more tightly by gravity.
12 November 2012: full circle?
If the theory quoted above, which suggests that very large stars may ultimately collapse to become quark stars, is true, then the way is open for the universe to come full circle. It started as a plasma of up quarks, down quarks and gluons, and the theory offers a way for matter to return to that embyonic composition. If quarks are indivisible and indestructible, the end-point of collapse would be a single mass of quarks. But for free quarks to be stable, the temperature and pressure have to be unimaginably great. As more and more quark matter is added by gravity to the terminal mass and gravitational collapse continues, perhaps another critical point would be reached in which free quarks could not continue to exist and the mass would explode or inflate. This, of course, would create a new universe!
13 November 2012
This morning, less than a day after I wrote the rather smug conclusion above, James Naughtie delivered something of a bombshell on the BBC’s Today programme. It seems that a major piece of astronomical research has shed new light on the accelerating expansion of the universe, the discovery of which led to the coining of the term ’dark energy’.
The new work shows that, as we would expect, gravity slowed expansion down for the first 7 billion years after the Big Bang. This is now thought to be due in large part to to the effect of dark matter - unsurprisingly, since it is believed to constitute 84% of the matter in the univers! Then expansion started to accelerate due, we are told, to the effect of dark energy.
The project involves a vast number of observations, but it is less than a third of the way through the planned work.
I can draw a crumb of comfort for my favoured oscillating-universe model from the notion that, if deceleration can be overtaken by acceleration, the reverse could happen. Acceleration requires the input of energy, and even dark energy must run out eventually! For more detail, read the BBC’s news page on this story, which has many links to other related stuff.
It will come as no surprise to anyone who has read this page that I really struggle with what Dr Matthew Pieri, interviewed by Naughtie, says about dark energy (except for the first words of the following quotation):
’We know very little about dark energy but one of our ideas is that it is a property of space itself - when you have more space, you have more energy. So, dark energy is something that increases with time. As the Universe expands, it gives us more space and therefore more energy, and at some point dark energy takes over from gravity to end the deceleration and drive an acceleration.’
Conveniently, that puts dark energy in the same mysterious place as gravity. I’m firmly convinced that gravity belongs with the various manifestations of electromagnetism - as a force rather than a distortion of that questionable entity called spacetime (though, interestingly, Pieri doesn’t go so far as to describe dark energy as a property of spacetime - just of space). If dark energy really is energy, it must be part of the conserved but constantly changing mix of matter and energy that has always made up the universe and always will. If it isn’t energy, then how the hell does it exert the unimaginable force that must be needed to accelerate the expansion of the entire universe? And if it is increasing with time, where does it come from? We know of no other form of energy that simply appears out of...well, empty space! Or is the conservation of mass and energy - one of the great foundations of physics - suddenly an outdated notion? If so, Wikipedia must be behind the times, because its page on the conservation of energy says:
’The law of conservation of energy...is a law of physics [my highlight]. It states that the total amount of energy in an isolated system [elsewhere it says ’Truly isolated systems cannot exist in nature, other than possibly the universe itself’] remains constant over time. The total energy is said to be conserved over time....this law means that energy can change its location within the system, and that it can change form within the system...but that energy can be neither created nor destroyed.’
Then there’s the assumption that the expansion of the universe ’gives us more space’. In my model, space - being a lot of absolutely nothing into which the finite universe itself is expanding - is already infinite, so we can’t acquire any more of it (or, if we could, we wouldn’t notice the difference!). The expansion of the universe obviously gives us more interstellar and intergalactic space, and we know they’re both teeming with stuff - gas, dust, particles, radiation, forces (including gravity) and, we are now asked to believe, both dark matter and dark energy - but that doesn’t make any of these properties of space itself.
That Einstein guy has a lot to answer for!
19 November 2012
Here’s a thought: is gravity a form of energy? If I am standing still at the top of a building and I drop a heavy object, it will accelerate towards the ground at the rate defined by Newton: thirty-two feet per second per second (or whatever that is in SI units) minus an adjustment for the resistance of the air (which is why feathers accelerate less rapidly than lumps of lead). The falling object acquires kinetic energy as it accelerates, and this appears to happen as an interaction between the masses of the object and planet Earth. Where does the energy come from? I seem to remember from O-level physics that the body has potential energy by virtue of where it starts from and acquires kinetic energy as it falls, but what does this all actually mean?
As far as I can see, there is no actual input of energy to the falling object: gravity does it all. And gravity, it seems, decelerated the expansion of the early universe without any input of energy. So why does whatever is now accelerating that expansion have to be a form of energy? So why can’t whatever is now believed to be accelerating the expansion of the universe just be a force similar to gravity? Why ’dark energy’? Why not antigravity - another fundamental force of nature, or even just another aspect of the gravity we all know? If unlike magnetic poles attract one another and like poles repel one another, could there be some sort of polarisation of gravity?
My imagination is starting to run away with me now! I’m thinking of a huge hollow sphere of dark matter outside the visible universe whose gravity (just the ordinary kind) is attracting the ordinary matter...
20 November 2012
This morning’s walk in the damp, leaf-strewn lanes of our village, with a hint of rain in the air, brought me right back down to earth. Only after I’d revisited the shell of dark matter round the universe, though!
I was thinking about the decelerating expansion of the early universe. Gravitational attraction is subject to the inverse square law, which says: ’a physical quantity or intensity is inversely proportional to the square of the distance from the source of that physical quantity’ (Wikipedia). This applies to all forms of radiation, sound and electric and magnetic forces. Put simply, it says that if we double the distance from the source, the intensity will reduce to a quarter (one divided by the square of two). Treble the distance and intensity reduces to one ninth. Quadruple it and it reduces to one sixteenth.
This is called an exponential effect, in which the effect changes far more dramatically than the cause. In the context of the expanding universe, it means that the mutual gravitational attraction of all matter would diminish very rapidly as that matter was spread over a greater and greater volume of space. So the decelerating effect of that gravity would diminish very rapidly.
Fortunately for us, it didn’t diminish rapidly enough to prevent hydrogen atoms moving closer together long enough for a gas cloud to be ’captured’ - an island of increasing gravity in an ocean of diminishing gravity. So galaxies formed, but in isolation, moving ever-further apart.
And as the distances between the participants in this decelerating expansion grew greater, the rate of deceleration must have grown less. Things went on moving apart, still slowing down but at a slower rate.
So what if some other, much weaker, force had been trying desperately to accelerate expansion since the Big Bang but had been defeated by deceleration due to gravity? Or, perhaps more accurately, what if this force and gravity were both working, producing a diminishing rate of deceleration bwteen them? And what if the weaker force were somehow not subject to the inverse square law and eventually took over from the ever-diminishing gravity, turning deceleration into acceleration? Could it be some residue of the vast input of energy delivered by the Big Bang, whatever form that took?
Today’s Observer had an article about research into WIMPs (see Wikipedia)- weakly-interacting massive particles - which are thought by some to be the mysterious dark matter. It seems that, without dark matter, all bodies in all the galaxies in the universe would simply fly away into space! This theory seems to be pretty well established, but how it meshes with the one that says that every galaxy has at its centre a super-massive black hole whose gravity holds everything else in orbit, I really don’t know. And how WIMPs, which should only interact very weakly with ’normal’ matter (to the extent that they can go straight through the earth and out the other side), could be powerful enough to hold galaxies together, I don’t know either!
As to how all this affects my cosy little model of the universe, I really don’t know!
23 November 2012: clinging to the wreckage...
...of my model, I found myself wondering about the supermassive black holes which are believed to be the ’centres-of-gravity’ of some, if not all, galaxies. The Observer article says that...
’...astronomers in the last century [the 20th, I assume!] decided to calculate the mass of galaxies in two different ways. They totalled up all the observable material – stars, planets and dust clouds – in a particular galaxy and worked out its mass that way. They also observed the speeds of the stars that orbited a galaxy and deduced its mass from that...Figures derived from the second method...invariably gave masses 10 times greater than those from the first method.’
I noted that the list of ’observable matter’ didn’t include black holes. If these really are the centres of each galaxy, surely their masses would be calculated by the second method described above...? Couldn’t they be the ’missing’ 90% of the ’deduced’ mass? That would bring us back to the comfortable Newtonian model - if you consider the awesome mass of the black holes to be comfortable! Given that none of this dark mass stuff has been detected, so it currently exists only in mathematical equations and the fevered minds of theoretical physicists, it seems safe to stick, for now, to what we think we know for sure.
I’ve just gone back to what I wrote about the Horizon programme that alerted me to the supermassive-black-hole theory. It seems from this that black holes are invisible, but at least one astronomer, Shep Doleman at the Massachussetts Institute of Technology, was searching for a faint ’halo’ which should, according the Einstein, correspond to the event horizon of the black hole.
So the ’observable material’ definitely wouldn’t include the black hole at the galactic centre. It’s hardly surprising, then, that the total mass calculated by the first method was seriously incomplete!
So can supermassive black holes be supermassive enough to explain the dynamics of a galaxy? Three years ago I wrote ’One scientist has plotted the orbits of the 30 stars closest to this monster [the Milky Way black hole] and has been able to calculate that the mass of the ’hole’ is of the order of four million times that of our sun.’ And then: ’Other galaxies are believed to have supermassive black holes at their centres which are several thousand times the mass of ours [the Milky Way one] - so maybe 20 billion (20,000,000,000) times the mass of the sun!’
So three years ago it was acceptable to use the orbits of the inner stars to calculate the mass of whatever was at the centre of a galaxy. Has anybody done the same sums with the orbits of the outer stars - the ones that seem to suggest that without dark matter galaxies would be forn to shreds by centrifugal force - or is this where the whole problem arises?
Three years on, Doleman seems to have escaped the notice of the normally-trusty Wikipedia, but a quick google took me to the man’s own website. Following a link from there found this pretty definitive confirmation of the invisibility of black holes (even if any radiation could escape from them):
’The nearest massive black hole is in the center of our Galaxy. Even though the size of this black hole is quite big, about 30 times the size of the Sun, it is at such a large distance from us that it appears about the same size as an orange on the Moon. Even though this is astonishingly small, the EHT [the Event Horizon Telescope] will have the ability to discern things at this fine scale.’
The EHT is Doleman’s ’Earth-size virtual telescope using the technique of Very Long Baseline Interferometry (VLBI).’ This looks like being the great-grand-daddy of all radio telescopes, which he says makes it extremely likely that his goal - ’to directly observe the immediate environment of a black hole with angular resolution comparable to the event horizon’ - will be achieved within the next decade.
It’s not clear from all this whether the suggested masses of these black holes approach the 90% of galactic mass needed to make sense of galaxies without proposing entirely theoretical forms of matter and energy. However, figures for the mass of the Milky Way quoted by Wikipedia suggest that they are not, and that ’Most of the mass of the Galaxy appears to be matter of unknown form which interacts with other matter through gravitational but not electromagnetic forces; this is dubbed dark matter.’ It looks as if the galaxy’s mass is of the order of one trillion solar masses, which is an awful lot more than the estimate of four million quoted earlier for our local black hole!
So much for my bright idea! It looks as if the dark matter theory is correct, but that sheds no light at all on the accelerating expansion of the universe - except to suggest that if dark energy exists, and whatever it is, it gets through a lot of work!
26 November 2012
I think I’m getting confused from trying to deal with new information about both dark matter (a label for something that clearly exists but has not yet been explained) and dark energy (a provisional name for something whose effects appear to have been observed but whose nature is a matter of pure conjecture).
There doesn’t appear to be any doubt that there is vastly more mass in the universe - and indeed in individual galaxies - than was previously thought. However, this seems to restore Newtonian gravity rather than undermine it.
We have to accept that the deceleration of the universe’s expansion has happened - which I seem to have explained above with the help of the inverse square law! - and that it has now been replaced by acceleration. This, however, is much more mysterious. For me, the law of conservation defeats the idea of a constant input of energy into the universe, so until the dark energy theorists come up with some solid evidence, I’m assuming that whatever is defeating gravity will eventually fizzle out and the residual gravity of all the galaxies will take control again. So I’m sticking stubbornly to to my model, because it’s the only one that, for me, preserves the idea that the total mass-energy of the universe we see today has always been here and always will be.
I am, however, keeping an open mind and an eye on developments!
Nothing seems to stand still in cosmology these days. Some very basic assumptions (some apparently cornerstones of the Einsteinian model of the universe) have just taken a serious knock by the discovery of the Huge-LQG (LQGs being large quasar groups) - by far the largest ’object’ in the known universe. This seems to be a group of active galactic nuclei (the supermassive black holes at the centre of galaxies) which radiate (I know - nothing is supposed to escape a black hole!) very powerfully and can therefore be seen from immense distances. The Huge-LQG is said to be some 9 billion light-years from Earth, so the radiation that revealed its existence has taken two-thirds of the age of the universe itself to reach Earth. It is 4 billion light-years across on its longest dimension, so light takes nearly a third of the age of the universe just to get from one end to the other.
For this group to be called an ’object’, the 73 quasars that make up the Huge-LQG must form a single gravitational system, like a galaxy only 73 times as big!
My instinctive reaction is to link this with my notion of the collapsing universe, but this needs more thought...
30 January 2013
...which I have duly been giving to the issue on my very wintry morning walks. And raising a lot of questions.
If this monster is, indeed, around 9 billion light-years from Earth, we have to ask how the hell it - and we - got there and here. We have to believe that the matter of which both the Huge-LQG and the Milky Way all started its travels with the big bang. For two objects to have moved 9 billion light-years apart in 13.7 billion years (the time since the big bang), their relative velocity must average roughly two-thirds of the speed of light. I’m sure I read somewhere (in my blunderings around Relativity theory) that the closer an object comes to the speed of light the more energy is needed to maintain acceleration, until, at light-speed, the energy requirement is infinite, and it is this that imposes the Cosmic Speed Limit of ’c’.
Now...the Milky Way is a pretty collossal chunk of mass, but the Huge-LQG is something else altogether - 73 galaxies-worth of mass. So where did the energy come from to power these two so far so fast? And, if the expansion of the universe is accelerating now, is the Huge-LQG accelerating? And, if so, what does that tell us about dark energy?
This needs even more thought!
31 January 2013
And the fruits of today’s early-morning hop through the puddles? The staggering insight that no two objects in the universe can be more than 13.7 billion light-years apart (all motion being relative) because that would require their relative velocity to exceed the speed of light. So the material universe cannot be more than 13.7 billion light-years across. Whereas, as I doggedly insist, the space into which it expands is infinite.
5 February 2013
Yes, I know this entry and the next are out of sequence, but this one follows logically on from the previous one!
After reading in The Observer the other week about a book called The Universe Inside You by Brian Clegg (a science writer but not a science professional) I downloaded the book to my Kindle. This morning I read the following: ’...the universe came into existence about 13.7 billion years ago. So we can only see light that has been travelling for 13.7 billion years...If everything stayed the same that would make the universe about 25 billion years across - but the universe has been expanding since it began. So the point the light set off from 13.7 billion years ago is now around 45 billion light years distant.’
A couple of ’matters arising’ here...
First, if the universe is more than 13.7 billion light years across or - as Clegg suggests - 27 billion light years, then the outermost objects have been travelling away from the epicentre of the big bang at an average speed much faster than the speed of light, and, as every Einsteinian knows, nothing can exceed the cosmic speed limit.
Second, his suggestion that the figure is 27 billion rather than 13.7 billion ignores the rule that all motion is relative: two objects cannot travel directly away from one another with individual speeds of more than half the speed of light.
As for the suggestion that the source of the light is now around 45 billion light-years distant - well, that seems to be just plain nonsense!
I decided to look up Brian Clegg on Twitter (see below)...
4 February 2013
If an LQG is seen as ’an object’, so must planetary systems, galaxies and presumably galactic clusters. So while the universe is expanding, these objects must be moving further apart without getting any bigger. And all ther matter must gradually be sucked into the supermassive black holes that form galactic nuclei, because the radiation that makes a quasar a quasar comes from the accretion zone, which is just outside the event horizon of the black hole and is highly active because all its matter is being torn out of orbit into the black hole. But...no matter being accreted: no radiation. No radiation: no quasar. So my proposal earlier on this page that all matter will eventually be absorbed into galactic nuclei seems to fit in with current thinking.
These nuclei - which presumably cease to be quasars when they have absorbed all available matter - will eventually be the only objects in the universe, radiating nothing but full of monstrous concentrations of matter and energy. LQGs, being held together by gravity, will presumably collapse too. And what happens when all the matter and energy in the universe is concentrated in a relatively small number of objects - I’ll call them SBVBH’s (seriously bloody vast black holes)?
Even assuming that dark energy is still at work, the immense gravitational fields of these unimaginably massive object might pull them together so that the universe itself undergoes gravitational collapse. And that is a recipe for another big bang. However many billions or trillions of years this process takes, we can be sure that mankind will be long gone. If we haven’t managed to render our planet uninhabitable, the death throes of our nice warm sun will have engulfed us. So the ultimate end of what, as an oscillating-universe believer, I must call the current universe can only be a matter for theoreticians.
20 February 2013
Here are my tweets to Brian Clegg and his replies. Three cheers to him for responding so promptly to my questions!
I remain unconvinced. Clegg says ’Matter can’t exceed light speed, but spacetime can expand faster than light speed’ - presumably dragging whatever is anchored at specific spacetime co-ordinates (or moving relative to those co-ordinates) along with it. So the matter isn’t moving at light speed - or faster - relative to spacetime but it is relative to the rest of the universe.
Moving the goalposts sounds like a good analogy!
In an admittedly brief trawl through Wikipedia I haven’t found any suggestion that spacetime is any kind of ’stuff’. If it isn’t stuff, then how can it expand. As for inflation, this seems to have happened in a brief blink of time occurring a much briefer blink just after the big bang, as the following Wikipedia extract says:
’The inflationary epoch comprises the first part of the electroweak epoch following the grand unification epoch. It lasted from 10−36 seconds after the Big Bang to sometime between 10−33 and 10−32 seconds. Following the inflationary period, the universe continued to expand, but at a slower rate.’
I’m not very good with scientific notation, but I think that means it lasted between a thousandth and a ten-thousandth of a second (I just tried working it out in Excel, but that didn’t help!). Not long, anyway - and no time at all after the bang itself. So what the hell that’s got to do with the ability of spacetime to expand is a mystery to me.
Tally-ho - it’s back to good old Newton for me!
I’ve said a lot about space and time earlier on this page. I’ve also seen references to space itself growing on various Wikipedia pages, and this makes no sense to me because I see space and time simply as measuring tools. The positions of objects are defined in terms of the three spatial dimensions. The positions of events and the statuses of processes also need to be defined in terms of time. Hence the notion of spacetime. But spacetime curving, as in Einstein’s theory of gravity, or expanding, as in Brian Clegg’s confident tweet above - sorry, I just don’t swallow it (further investigation below).
What I find concerning about the Clegg quote that kicked all this off is how certain he sounds (as he does in his tweets). All this stuff is theory, and the Wikipedia pages I’ve used for my research emphasise all this. I’d be more comfortable reading Clegg’s stuff if he would acknowledge this and quote his sources.
So here’s where I seem to be...
We can’t possibly be seeing objects 13.7 billion light-years away because it would take the entire life of the universe for their light to reach us. We might see objects half that distance away, provided they have been moving away from us at light-speed ever since the big bang. But massive matter, as distinct from massless particles like photons, cannot accelerate to light-speed because that would need a infinite in put of energy. So nothing we see can possibly be more than a billion light-years or so away. QED and smug smile.
Except that the guys researching the Huge-LQG mentioned earlier on this page reckon that it’s around 9 billion light years away...
28 Feburary 2013
I’ve just finished The Universe Inside You. I found it an interesting and entertaining romp through many areas of science, but I’m not sure the highlights justified a double-page spread in The Observer’s New Review. The amount of pre-knowledge that Clegg assumes in his reader seems to vary rather wildly - I only got lost or lost interest a few times, but then I’ve done a lot of other reading around science. Other readers, looking for more of an introduction to science, might struggle or even give up. And he also seems to drift quite a way away from the basic idea, which is to extract as much science as possible by an exploration of the human body. I’d also like to have seen more credit given to the originators or current researchers of the material he looks at.
5 March 2013
Still bugged by the size-of-the-universe conundrum on my foggy walk this morning, I decided today was the day to have another look at what is known. Once free of dreary chores I opened Wikipedia and searched for ’most distant object’. I got an article containing very little discussion but several tables, the first of which is headed ’List of the most distant astronomical objects’ with the note ’as of 2012’.
To my immense relief, top of the list is something called UDFj-39546284, described as a protogalaxy (a galaxy in the process of formation) which is 13.37 billion light years away. UDFj-39546284 and the Milky Way have clearly been flying apart at not much less than the speed of light for almost the entire life of the universe, but crucially this does not back up Brian Clegg’s figures quoted above.
My relief was short-lived. I saw the note at the bottom of the table: ’The tabulated distance is the light travel distance, which has no direct physical significance [my highlight]. See discussion at Distance_measures_(cosmology) and Observable_Universe’. Brief visits to these two links convinced me that there are several different and conflicting models of the universe, none of which can be understood my someone of my profoundly limited mathematical knowledge.
Anyway, it is comforting to know that nobody has yet observed anything more than 13.37 billion light years away. Anything else is purely theoretical!
Of course this does raise a whole other set of questions. If these sources are so far away (apparently the measurement is based on their red shift), it has taken almost the entire life of the universe for their light to reach us. So how did they get that far away within a very tiny fraction of the universe’s lifetime? They would have had to travel at almost infinite speeds, never mind the speed of light! If my simplistic model makes any kind of sense, this just isn’t possible.
13 March 2013
I’ve just found a Wikipedia page that seems to back up Clegg’s assertion.
Then I found an elegant diagram on the Metric expansion of space page which suggests that most of the expansion of the universe happened in the inflationary epoch, which lasted an infinitesimally tiny amount of time - ’...from 10−36 seconds after the Big Bang to sometime between 10−33 and 10−32 seconds.’ I tried to unravel this insanely tiny fraction earlier on this page, but I suspect that I failed. 10−36 is 1 with a decimal point and 36 zeroes before it (I think). ’Show your working’ was what I was told to do in maths tests, so let’s have a go. 100 is zero (no tens multiplied together). So 10−1 is one tenth, which is actually 1 with a point and no zeroes before it (0.1). It follows that 10−2 is one hundredth (0.01), 10−3 is one thousandth (0.001), 10−4 is one ten-thousandth (0.0001), 10−5 is one hundred-thousandth (0.00001) and 10−6 is one millionth (0.000001). So actually 10−36 is 1 with a point and 35 zeroes in front of it - not 36! Counting on my fingers (for scientific notation?!!!) I reckon it takes another six zeroes (total 11) to get to one million-millionth (one trillionth), six more (total 17) to one million-million-millionth (one quadrillionth), six more (total 23) for one million-million-million-millionth (one quintillionth), six more (total 29) for one million-million-million-million-millionth, six more (total 35) for one million-million-million-million-million-millionth, so 10−36 is actually one ten-million-million-million-million-million-millionth! 10−32 is quite a lot bigger than 10−36 - ten thousand times?
But - even if I’ve got all these crazy numbers totally round my neck, which is highly likely - we’re still talking about the universe getting somewhere near its present size in an inconceivably short time. This in turn would make the ’fact’ that the most distant objects in the universe got most of the way to where they now are well inside the first instants after the Big Bang. Of course, they would have had to travel many many times faster than light to get there, so I’m not a lot wiser! But at least I can see where Clegg was coming from.
14 March 2013
Actually, I thought on my walk, this may actually make some kind of sense after all. Back home, I looked more carefully at the Wikipedia diagram. I also discovered is available in an enlarged version and (thanks to its creators at NASA) is in the public domain, so here it is:
most of the expansion of the universe seems to have happened in the inflation period which is labelled as lasting only 380,000 years. (I have to own up to the fact that the caption says ’This diagram can be confusing because the expansion of space looks like it is happening into an empty "nothingness". However, this is a choice made for convenience of visualization: it is not a part of the physical models which describe the expansion.’ But the scaling must have some significance!
So here’s what I thought...
During inflation, the universe consisted of a quark plasma. Now quarks aren’t actually matter: they had to buddy-up to form protons which then had to capture electrons before the first matter - hydrogen atoms - formed. So maybe quark plasma is exempted from Einstein’s cosmic speed limit. After all, quarks weren’t even proposed until 1964, nine years after the old boy’s death and 59 years after he published his theory of relativity, and they were first ’seen’ in a linear accelerator in 1968. Maybe the 380,000-year inflation of the quark plasma really did make the universe most of the size it is today and expansion has made a relatively minor contribution to its current size. With nothing but zillions of the most fundamental particles and a near infinite supply of energy, surely anything is possible! After all, thre wasn?t even a universe at all at that stage, so maybe the laws of physics hadn?t come into being...
I know: the clever guys get round all this by saying that objects getting further apart in the expanding universe aren’t actually moving - it’s the space (or spacetime) that’s expanding. But, as I wrote in the displaced section below, I can’t get my head round that. Spacetime is only a mathematical model. So I’ll stick to my Newtonian version with the quark-plasma idea as a get-out! It makes a lot more sense to my simple mind, and really that’s all I’m looking for.
Spacetime and gravity
Going back to my thoughts, above, about spacetime, I was again comforted - this time by Wikipedia’s main page on the subject: ’In physics, spacetime...is any mathematical model that combines space and time into a single continuum.’ So, as I thought, it isn’t stuff at all - it’s just one human way of looking at the universe. It follows that curved spacetime, as used by Einstein to ’explain’ gravity, is just a different model using bent lines instead of straight ones. But does he explain how they got bent...?
So what is really being distorted by the mass of the sun (and the Earth itself) to keep us in our elliptical orbit...? There must be some stuff somewhere, because we live in something a lot more solid than a mathematical model! I can only make sense of gravity by comparing it with magnetism, something we manipulate with great precision - and have been doing for centuries. Force, particle, whatever...why does gravity have to be any weirder than magnetism? Or don’t we actually have an explanation for how magnetism actually works either...?
22 March 2012: It’s all happening in cosmology!
News seems to be coming through thick and fast from the researchers these days. The latest is the 2013 data release from the European Space Agency’s Planck space observatory, which has given us a more detailed version of the now-familiar elliptical image of the cosmic microwave background (’the relic radiation from the Big Bang’ according to the ESA website, which explains the significance of the image in reasonably plain language). This has provided more precise estimates of various key figures about the universe, including a revision of the familiar 13.7 billion-year age of the universe to 13.796±0.058 billion, so at the top end of the tolerance it could in fact be just over 13.8 billion. No big deal, I suppose, but a load of new and more precise data for the cosmologists to mull over! There are also more precise estimates of the percentages of ordinary matter (4.9%), dark matter (26.8 %)and dark energy (68.3 %)that are believed to make up the total mass of the universe. Here is the image, which I assume is in the public domain as I lifted it from a news website. The ESA website says that features revealed by the observations distilled in this image, which took 15.5 months, ’challenge the foundations of our current understanding of the Universe’.
Googling ’planck cmb image’ will provide many other images. The one below, from the ESA website, compares the best pre-Planck image with the one above. The leap in clarity and resolution is astonishing.
25 March 2013
I watched the Horizon programme What Happened Before the Big Bang? again recently, and was pleased to see that many of the scientists featured were happy to think about a time before the big bang. No doubt they have far more sophisticated arguments for something existing before the bang than I do, but this reinforces my belief - based on my simple faith in the laws of conservation of mass and energy - that the total mass/energy that exists in the universe must always have existed and will always exist.
Here’s an interesting thought...
If the universe consisted of a quark plasma during inflation, there was no true matter - just energy. That could have allowed inflation to be much faster than the speed of light. If, in the death-throes of the universe, all matter will be absorbed by black holes, as I have suggested earlier, will this then be a return to conditions during inflation?
Then there’s the immense gravity of black holes. When the supermassive black hole at the centre of a galaxy has sucked in all the matter in the galaxy, will its gravity be greater - or, in some way, more concentrated - than that of the whole galaxy before gravitational collapse? And will a universe consisting of nothing but a reducing number of growing black holes respond to dark energy in the same way as our material universe: by accelerating its rate of expansion? And, if so, how long will the dark energy (whatever it is) last, providing the force needed to accelerate all these black holes toward lightspeed?
And, if the universe of black holes actually does begin to collapse, could its collapse accelerate beyond lightspeed? The same quarks far exceeded lightspeed during inflation, after all. And, if so, what might happen when everything smashes together. A very big bang indeed, you might think...
9 April 2013
I developed the ideas in the last section a bit further this morning, chatting to my phantom audience as I walked.
Dark energy - assuming, as one must, that it is some recognisable form of energy since it is accelerating vast amounts of massive matter - must eventually all be converted into the kinetic energy of the galaxies as the universe expands and they hurtle further and further apart.
Incidentally, I picked up the idea somewhere recently that the galaxies themselves (and perhaps galactic clusters) are not expanding, held together as they are by their own internal gravitational systems, which seems to me to call into question the notion of it being space which is expanding. So the accretion of orbiting matter into the central black holes will presumably continue, presumably increasing the gravitational attraction of the black holes and therefore the collapse of the galaxies themselves.
So, from my primitive Newtonian viewpoint, it seems that each galaxy will eventually be reduced to a singularity of collossal mass with corresponding gravity.
There’s also the matter of the equivalence of mass and energy. A fully-charged battery has more mass than it did when discharged - and in fact some of my most powerful rechargeables are noticeably fatter after charging - so much so that they won’t fit into my Canon flashgun. Will the dead galaxies have much more mass - and therefore much more gravity - than they had when the expansion of the universe was happening far more slowly? And, if so, when acceleration stops (all dark energy having been ’captured’ by the galaxies as kinetic enery) will this increased gravity be able to slow expansion, stop it and then pull everything back together?
Then I came to the likely effect of this immense number of hypermassive black holes accelerating towards one another. If the quark plasma of the early, inflating universe was able to exceed the cosmic speed limit, as seems to have been the case according to the standard model, will the quark matter of the black holes be similarly unconstrained? Will the ’big crunch’ be a coming together of all the matter (proto-matter?) in the universe at a speed vastly in excess of that of light? And, if it is, wouldn’t a new big bang be by far the most likely result?
Or will the insubstantial quark matter, accelerated by gravity, simply hurtle past the ’centre of gravity’ and carry on outwards in all directions at whatever its terminal velocity was at the point of singularity? Not so much a big bang as a big overshoot? And a new inflationary epoch?
And, will the beautifully simple raw materials of up-quarks, down-quarks and electrons inevitably produce hydrogen, galaxies, stars (all fusing nuclei to generate the same lighter elements as last time) and supernovae (all producing the same heavier elements to be sucked from nebulae into the next generation of stars)? In short, wouldn’t the long-term outcome be a universe with identical chemistry to the present one?
Doesn’t the gloriously simple construction-set of quarks, electrons, the weak and strong interactions and the force of gravity guarantee that the evolution of the next universe will be very like that of this one?
It’s an attractive idea that, however much of a mess we humans make of our tiny planet lurking in a solar system on the outer fringes of a pretty average galaxy, nature will ultimately clean it up and start again. What a pity we won’t be able to leave a legacy of our own experience behind for the next species intelligent enough to fall into the same traps!
Personal site for Paul Marsden: frustrated writer; experimental cook and all-round foodie; amateur wine-importer; former copywriter and press-officer; former teacher, teacher-trainer, educational software developer and documenter; still a professional web-developer but mostly retired.
This site was transferred in June 2005 to the Sites4Doctors Site Management System, and has been developed and maintained there ever since.