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Some thoughts about the universe
Update on the expansion of the universe, below, (12 April 2010). Exciting new stuff from the 4 November 2009, including an amazing BBC Horizon programme, towards the end of this page! And even more from the 11 February 2010 after a Horizon programme about infinity...
We have to take an awful lot of what theoretical physicists tell us about the origin and nature of the universe on trust. The scientific concepts are too difficult - and especially too counter-intuitive - to be understood by anyone outside the field. Iíve had a couple of goes at Hawkingís A Brief History of Time, and I wouldnít for a moment claim to have understood it - gained some insight and some clues, sure, but in the end we just have to accept that these guys know a hell of a lot more than we do, so their interpretations of the evidence have to be a lot closer to the mark than anything our intuition tells us.
Having said that, there seems to be a huge amount of conjecture going on. The process seems to involve looking at the evidence we already have, putting oneís best interpretation on it, conjecturing about what, as a result, ímustí be there and then going off to look for the evidence that it is. The Higgs Boson is the obvious current example: the search for it has justified the massively expensive Large Hadron Collider project at CERN, so someone must have put up a pretty convincing argument for its existence. Thereís also much older stuff that defeats me - particularly Einsteinís stuff about space-time being curved and this apparently providing an explanataion of gravity, which, otherwise, still seems to remain a bit of a mystery.
I think we lay-persons (I grew up with a father who had a BSc(Hons) in Chemistry, but my sole scientific qualification is a bare pass at O-level in Physics-with-Chemistry - the exam for kids who werenít expected to handle the two subjects separately!) should probably pay only passing attention to whatís going on at the leading edge of research, and wait for things to become a bit clearer.
We know gravity is there because we experience it in every waking moment (Iíve been sitting on this chair long enough for gravity to make my backside ache). Okay, so relativity explains some slight leaks in Newtons laws, but those laws have sufficed to get us to the moon and our toys to the outer reaches of the Solar System, and itís going to be a very long time before we do interstellar navigation to the extent that Newtonís errors become a problem.
I was a bit confused (well, quite a lot, actually) by the bit in Professor Brian Coxís recent BBC2 Horizon documentary on the quest for controlled nuclear fusion, where he demonstrated the relationship between gravity and the curvature of space with a rubber sheet. This had a heavy ball in the middle, which pulled the sheet down to a central point, supposedly to demonstrate the curvature of space around a heavy body like a star. He demonstrated the effect of gravity by rolling a smaller ball in orbit around the big one so that it spiralled in and collided with it. My problem is that the demonstration depended on the Earthís gravity. I guess thatís the trouble with trying to explain the behaviour of matter in a multidimensional universe when you only have access to three!
And the belief that all atoms are (and therefore matter is) composed of neutrons, protons and electrons is pretty well established now - it seems highly unlikely that the atomic bomb, the nuclear fission reactor and the hydrogen bomb, which were all developed on the basis of that belief, could have been developed successfully if that model had been seriously flawed. Whether or not these ífamiliarí subatomic particles are indivisible, or are actually made of things called quarks, or are actually just quarks with different properties, seems to be neither here nor there. We can split atomic nuclei either explosively in atomic bombs or under control in nuclear reactors, releasing vast amounts of energy in the process. And we can fuse nuclei together explosively in hydrogen bombs, with even vaster releases of energy, though we have yet to get this process - the Holy Grail of nuclear fusion - under the sort of control needed for fusion power stations. Thatís a pity, because fusion releases most of the energy of matter. If Cox is to be believed (and Iím sure he is), a single US dollar bill has a much energy as a hydrogen bomb.
This would certainly bear out Einsteinís famous equation: E=mc2. The Relativity Man says that matter and energy are interchangeable, and that the energy of a quantity of matter is equal to its mass multiplied by the square of the speed of light. Now the speed of light is a hell of a lot, and its square is even more inconceivably vast. So what he is saying, basically, is that hardly any matter at all, converted to energy with 100% efficiency, would yield an immense amount of energy. Given the intense heat, eye-blistering flash and thunderous wallop of a hydrogen bomb, which must involve fusing the nuclei of a relatively modest amount of the lightest gas in the universe, we have to believe him.
The Worsley School website has a neat explanation. Apparently a kilogram (litre, roughly) of water contains 111 grams (about a quarter of a pound) of hydrogen. The speed of light is 300,000,000 metres per second. Multiplying 111 by the square of that, gives an energy value of 10,000,000,000,000,000 (10 trillion) Joules. A Joule isnít a lot of energy, but this is roughly the amount of energy obtained by burning 10 million gallons of petrol! Worsley is in Canada, so those might be measly American gallons (eight 16-ounce pints), but you get the idea. Obviously burning is a lot less efficient than nuclear fusion: compare the heat from burning a dollar bill with that from subjecting it to total fusion...
Anyway, both fission and fusion, the most violent methods we have of interfering with the structure of matter, seem to leave the neutron/electron/proton structure rearranged but intact, so that will do me for now.
I guess The Big Bang is now pretty well established as the explanation of how the universe came into being, and until recently I understood (or thought I did!) that it accelerated all the matter that makes up the universe to a high enough velocity to ensure that gravity would never first slow down and then stop its expansion. Now it seems that The Standard Model - all the maths that astronomers and physicists and cosmologists and astrophysicists use to explain how the universe works - has until recently assumed just this. However, I have heard nothing about the universe then beginning to collapse. This is rather a pity, because I always liked the Oscillating Universe theory, which I first read about in an article by the great science-fiction writer Isaac Asimov: it proposed that the universe would indeed stop growing and start shrinking, collapsing in on itself until it reached some sort of critical mass and exploded again, starting a new cycle. Fred Hoyleís alternative, the Steady State theory, never fitted the astronomical evidence.
12 April 1020 Recent observations seem to have shown that the universe is not expanding at a steady or reducing speed, but that the process is in fact accelerating. The current theory used to explain this is that something called dark energy is lurking out there in vast amounts. This became clear enough to me to justify this update from a new BBC4 series, Beautiful Minds: in the first episode, Professor Dame Susan Jocelyn Bell Burnell (to give her full name and titles) spoke at length, and with beautiful clarity, about many matters astrophysical, always emphasising that scientists should never claim to have found the ultimate answer to anything. Is this the explanation for red shift - the phenomenon in which the most distant objects appear redder than the nearer ones because the Doppler effect is increasing the wavelengths of the radiation we get back from them?
That is not the only recently-discovered change. There are two other ?dark? entities that appear to be messing with long-established beliefs about the universe. I will write about all three of these separately.
The closest estimate seems to be that the Big Bang occurred some 13.7 billion (13,700,000,000) years ago, starting at something called a Singularity, when all the matter was condensed into an infinitely tiny speck of immense mass. I understand that this then behaved like the chunk of plutonium in an atomic bomb, exploding with immense force to produce a rapidly expanding cloud of hydrogen and helium atoms (the two lightest elements) - or, according to more recent thinking, of quarks and electrons which, at some point fairly soon after The Bang, combined to form hydrogen and/or helium nuclei and then atoms. Even this vast cataclysm didnít spread the matter evenly, but created a sort of lumpy porridge in which the gravity of the denser bits of cloud gradually sucked in more and more atoms from their surroundings, creating stars. When the stars became dense enough, the immense temperatures and pressures at their cores triggered nuclear fusion: atomic nuclei fused together to form bigger and bigger (and therefore heavier and heavier) atoms, building more and more of the elements we are familiar with - probably even elements as heavy as iron.
(If this process isnít obvious to you, you need to understand that all the elements are made of the same bits. They only differ in the number of neutrons and protons in their atomic nuclei and the corresponding numbers of electrons trapped in orbit around those nuclei. Fusion means íjoining togetherí, so by joining together - fusing, hence fusion - two atoms of a lighter element, such as hydrogen, you create one atom of a heavier one - in this case helium. This we can do under more-or-less control in an H-bomb. It takes more than human ingenuity to do it with much heavier atoms.)
Then some stars exploded as supernovas (supernovae?), in which all the even-heavier elements, right up to uranium, were created and scattered into space. (It?s intriguing to ponder why the explosion of a single star can achieve this, but The Big Bang - which, you would think, was far more violent than a supernova - only managed to produce a cloud of quarks and electrons. Maybe one bang, however big, could only achieve one kind of transition - in the big one?s case, from whatever, if anything, was the raw material for quarks and electrons, which should be nothing if The Bang really was the beginning of it all...) Gravity then stepped in to create, from these, more stars and planets - and ultimately living things came into being. All this while everything was still rushing away from the site of the Big Bang at inconceivable speed.
Scientists claim to be seeing further back in time as they see further into space, and they interpret what they see at the outer limits of vision (whether in the visible light portion of the spectrum or by decoding radio and cosmic waves) as giving more and more insight into conditions shortly (in cosmic terms) after The Big Bang. But it is clear that they are not going to be able to see futher back than that event. At that point they will simply run out of evidence.
Infinity and all that
Okay - hereís a conundrum. If nothing is slowing down the expansion of the universe it is going to go on forever. Or is it? The universe we know is of finite size, but it is expanding. And the rate of expansion isnít slowing. But is there any limit to its potential expansion? Presumably what is beyond its outer limits is space. An awful lot of space - if you can have a lot of nothing.
If space were finite, then we would be faced with the problem of what is beyond it. This is a bit like the state of affairs when the Earth was presumed to be flat and of limited size: where would you go if you fell off the edge? So it seems safe to assume that space is infinite: seeing as it is, by definition, composed of absolutely nothing, it is impossible to conceive of it having a boundary because there would have to be something else beyond that boundary. So there is no reason to doubt that the near-vacuum of space goes on forever.
So will the universe go on getting bigger and more spread out forever? I am ignoring any implication of Einsteinís thinking because I simply donít understand it. If space is curved, then maybe it sort of doubles back on itself so that if you go far enough you get back to where you started, as on the spherical Earth. But what does the idea of space being curved actually mean? How can a vast amount of nothing at all possibly have any kind of shape? Sorry, Dr Einstein - Iím lost, so Iíll stick with a notion of space that makes some kind of intuitive sense!
And if, as seems to be believed, the universe goes on much further than any current human instruments can íseeí, how do we know how far it goes?
And how do we know that somewhere, far beyond the actual edge, there arenít other universes born (or being born) in their own separate Big Bangs? What if, in our infinite space, there is a vast - or even infinite - number of other universes? And, if there are, what will happen if the outermost galaxies and stars of our universe ever encounter the gravitational fields of those of other universes?
Then thereís the supposed fourth dimension of time. Did this have a beginning and will it have an end? Or has time, and consequently space, just always been there? And will they always be there? If so, what was occupying space before The Big Bang? Science has something called the laws of conservation of matter and energy. We donít believe that either of these commodities can either spring mysteriously into being or suddenly be extinguished. Why, therefore, should we believe that there was nothing before The Big Bang? That seems to bring us back to magic and God and similar stuff, which is just an intellectual cop-out.
But the astrophysicists insist that, although some bits of our universe are drawn together by their own gravity, the universe as a whole will go on expanding rather than slow down and begin collapsing. Okay, how about my suggestion that our universe is just one of many, just as our solar system and our galaxy are? Maybe the interaction of two colliding universes will create something that does start collapsing, leading ultimately to another Even Bigger Bang that creates an even bigger universe. And maybe this process will go on repeating itself into - yes! - eternity. One thing is for sure: anyone observing the consequences of that Even Bigger Bang from one of the planets it creates is unlikely to be able to detect any evidence of time before the Bang. And, of course, scientists only theorise on the basis of evidence.
Another thought: if there are universes beyond our own, radiation coming towards us from them would have taken so long to reach our area of space that it might have been annihilated by our own little local Big Bang - in which case there is probably no way in which we could ever be aware of them.
All this is, of course, the simplistic conjecturing of an uneducated mind, unable to begin dealing with the notion of a universe, or space, with four or more dimensions.
In human terms, of course, itís all irrelevant. Even if our species manages to survive its own present catastrophic impact on the balance of our planet, weíll be long gone before any of this really matters because our sun will have died.
However, if we can harness fusion - and Cox tells us that most scientists believe it will be done within the next few decades - understanding all this stuff may keep us going for a few more millennia.
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.
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