Sometimes observations are hard to explain. So you just have to tack on the best ad-hoc explanation that fits the facts, even if the explanation itself is lacking the nitty-gritty details. Astronomy went through such an exercise when anyone who was anyone said that the Earth was the centre of all things, and all things revolved around the Earth. That didn’t end very well. I suspect that modern cosmology is in a similar situation that ultimately won’t end well as far as the status quo is concerned either.
Once upon a time humans thought and believed that the Earth was the centre of the cosmos and that all things revolved around the Earth. When it came to the Sun and the Moon, things worked out pretty smoothly. The Moon does go around the Earth and the Sun damn well appears to. The ‘fixed’ stars also appear to go around the Earth and provide no ammunition to suggest otherwise.
But the ‘wandering stars’, the planets, were different horses of other colours. Their motions, assumed to be going round the Earth, were difficult to reconcile with that stationary Earth in the middle. Nobody (at the time) was willing to abandon the Earth-centred cosmos, and so the motions of the planets had to be tweaked in order to get observation and theory to gel. Thus was invented the epicycle.
Planets were assumed to go through various loop-the-loops and other gyrations or acrobatics (collectively called epicycles) in order to conform to observation. But original epicycles had in turn to be provided with second generation epicycles as observations still didn’t fit the ‘facts’, then third generation epicycles tacked on to the second generation tacked on to the original generation, until things go so out of hand and complicated that everything just collapsed in a heap. That resulted in a paradigm shift.
When the positions of the Earth and Sun were reversed, everything fell into place, theory matched observation (once ellipses were substituted for circles – the perfect circle was yet another once upon a time when humans were dictating to nature what nature should do requirement), and all those epicycles fell by the wayside.
We seem to face a similar situation today when it comes to modern cosmology. We have lots of observations that require ever increasing ad hoc epicycles to account for them.
Many an observation has been made in the sciences, and then to explain a group of them, some sort of all encompassing explanation is given. That in turn results in various issues or problems and so to resolve them, another all encompassing explanation is given to explain that lot of them, and that in turn, well etc. etc. A clear case in point revolves around the standard model of cosmology.
Astronomers observe the universe – obviously. Certain observations in need of explanation have given rise to just such an explanation, albeit incomplete and rather unsatisfactory. That trilogy of observations is: 1) galactic redshifts; 2) The cosmic microwave background radiation (CMBR); and 3) the ratio/abundance of hydrogen & helium.
The galactic redshift observation boils down to the fact that nearly all galaxies are moving away from each other and the distances between them are in relation to their velocities such that galaxies moving at X velocity will be Y distance apart; galaxies that are 2X velocities will be 2Y distances apart and so on. Translated, it’s what you would expect to see with respect to all the bits and pieces flying off on an exploding stick of dynamite. Thus we have an expanding Universe, and, by running the ‘film’ or the clock backwards, the Universe will have come to a ‘point’ roughly 13.7 billion years ago.
The detection of the Cosmic Microwave Background Radiation (a cosmic temperature detectable in part as static or hiss on your TV set when tuned between stations) was in accordance with theoretical predictions if the cosmos started out as an extremely hot explosion and slowly cooled down as the Universe expanded.
Lastly, when one observes and calculates the relative abundance of hydrogen and helium in the Universe, the two simplest of elements, that ratio is what you’d expect given known interactions part and parcel of particle physics under the extremes of temperature and pressure that would be expected in a high temperature explosion.
So, the Big Bang gets a heads up. Things are looking good. But, and there’s always a ‘but’!
There are immediately several issues with respect to this cosmic explosion termed the Big Bang. Firstly, it created time (no explanation or recipe given as to how); secondly it created space (no explanation or recipe given for that either); thirdly it created matter and energy (again, no explanation or recipe, given); fourthly the ‘bang’ wasn’t ‘big’ since cosmologists choose to run the clock back as far as they can and thus cram the entire Universe back into a volume less than that of a pinhead; and lastly, no energy source for the ‘bang’ is given. In fact I’ve often read that apparently no energy source was actually necessary (because the Universe is energy neutral – it has as much positive energy as negative energy), which I find more than slightly odd.
However, postulating the Big Bang to explain the above trilogy of observations caused issues with another trilogy of observations. These observations centred on: 1) the horizon problem; 2) the flatness problem and 3) the monopole problem
The horizon problem – contact between two regions – is a problem in that if you look at exact opposite regions of the Universe; you tend to see pretty much the exact same thing, especially when it comes to temperature. So what? Well, in order for things to achieve equilibrium, your hot cup of coffee cooling off while the kitchen gets ever so slightly warmer until both coffee and room are the same temperature, requires that the two regions (coffee and room) be in relatively close proximity since the exchange can only happen at velocities equal to or less than the speed of light. If two opposite areas of the sky, looking deep into space, are the same temperature, it requires that these two regions were once close together, close enough for equilibrium at or less than the speed of light to have taken place in order to even conditions out. Unfortunately, the distances observed between opposite points in the sky are such that uniformity could not have been possible. They are now out of contact with each other – beyond each other’s ‘horizon’ so any bits of non-uniformity between regions that eventuated way back when should have persisted – and when we look that deep into space we are looking way back when. We need some serious additional oomph to get uniformity between regions from way, way back then (i.e. – immediately post Big Bang) out to currently observed distances.
The flatness problem revolves around the observation that the Universe is fine tuned with respect to the density of matter and energy contained within, a density that has resulted in a just so ‘flat’ universe. Translated, a flat universe is one where Euclidian geometry holds sway (the three angles of a triangle add up to 180 degrees). Now if the density was greater, the Universe would be closed, like a sphere (i.e. – the Earth), where the angles of a triangle on the surface add up to more than 180 degrees. If the density were less, the Universe would be an open (i.e. – saddle-shaped) hyperbolic Universe where the angles of a triangle add up to less than 180 degrees. If you have a potentially wide range of possible densities, it’s amazing that our Universe has that just-so flatness.
The monopole problem is that under the conditions of the Big Bang, one should have generated monopoles – magnets with either a north pole, or a south pole, but not both. Alas, no monopoles have ever been detected or observed. They appear to be rarer than hen’s teeth.
Well, the way to circumnavigate those problems is to propose not just an original Big Bang explosion, but an additional super-ultra ‘explosion’ that speeded up the expansion of the Universe, ever so briefly, by a very, very, very large factor indeed. This secondary ‘explosion’ was termed Inflation. Inflation made the expansion rate of the Universe caused by the Big Bang to appear almost insignificant.
To be continued.
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