How much we really owe to Einstein
Einstein was saying in his “Theory of Gravity, General Relativity” that space can be curved, and he included the concept of ‘space-time’ which although is difficult to imagine, is highly plausible!
In two dimensions a flat, spherical or hyperbolic space, are the three basic shapes. Close up, they will look like flat surfaces, but very different from a distance.
Think about tiling a flat space with identical squares like on a chessboard for instance, and something similar with a three dimensional space using identical cubes – this is simple – however, if space is like a huge dodecahedron and hyperbolic with curvatures, it is very different to the chessboard analogy. Tiling such a thing isn’t such an easy task but offers a good analogy if space is really like this, though we are unlikely to ever be sure one way or the other.
Another curious property of curved space is the behaviour of parallel straight lines. In a flat space, straight lines that are parallel always stay parallel. However, in curved space these lines become great circles just like the Equator. Lines of longitude, latitude and the world famous Meridian at Greenwich, are slow straight lines that are really curved!
Straight lines on a sphere can start off parallel, but they eventually meet; nearby lines of constant longitude at the equator are parallel but they meet at the North and South Poles – a great many you can see at the top of any globe.
In hyperbolic space, parallel lines have the opposite behaviour: they diverge. This divergence (or convergence on a sphere) tells us, how curved the space is, and whether it is hyperbolic or spherical.
There are other curiosities too: for example, the angles of a triangle add up to 180 degrees in flat space, but add to less than 180 degrees in a hyperbolic space, and to more than 180 degrees in spherical space. This gives us an idea of what we are talking about when Einstein suggested that space was / is curved, because the measurements are important and we can estimate these measurements reasonably accurately using his equations.
The circumferences of circles are strange to: for a fixed radius the circumference is bigger in hyperbolic space and smaller in spherical space, and again this is relevant for calculation purposes.
The balloon analogy of the expanding Universe assumes that the Universe, has spherical, spatial, curvature; but this is not necessarily the case: if the universe is flat or hyperbolic then the expanding balloon is wrong.
It has to have some shape, and one alternative to this is the Expanding Saddle which suggests that space is infinite in size because it can’t have edges.
There is a way for a flat or hyperbolic space to not be infinite in size. When thinking of a video game where you disappear off the right hand side of the screen and reappear on the left; this is a good example, thus if the Universe is like that, there may be a problem if it is expanding too quickly.
Spatial curvature of the Universe is very interesting. We could be in a spherical Universe like a balloon being inflated, a wrap around saddle shape, or something else; thus, we can measure the contents of the Universe approximately, and with Einstein’s theory, we can calculate the the geometry of the Universe approximately as well.
It turns out that the Universe comes out as very flat to us because it is so large. If there’s any curvature, whether saddle shaped, or sphere shaped, it’s only apparent at sizes that are much bigger, and that cannot be measured in our observable Universe.
Space could be curved and of any size, so why does our observable Universe turn out to be almost perfectly flat?
This is known as the Flatness Problem.
If space is curved, why does it appear flat?
Inflation is probably the best solution that astronomers and cosmologist have to the Horizon Problem and the Flatness Problem.
It is puzzling because different parts of the CMB end up almost exactly identical. The inflation approach supposes that something unidentified from the history of the Universe, triggered a much faster phase of expansion known as inflation.
The effect of this faster expansion, is one explanation for why space looks flat. But what triggered the expanding universe to speed up this expansion all of a sudden and lead to Inflation?
Inflation is the exponential expansion of space in the first few seconds of the Universe, shortly after the Big Bang. Following the inflationary period, the universe continues to expand, but at a less accelerated rate.
Scientists may have got the real size of the observable Universe wrong, but how could it be much bigger?
This may explain why the CMB seems uniform, mostly. There is a patch of sky that seems to have been out of contact, but was much closer together, before inflation flung it apart.
Astronomers still use the term observable Universe, to mean predicted size without inflation, even though there is a fairly wide support for Inflation Theory.
This is to do with the extreme redshift of any pre-inflation signal being undetectable by any known technology, and it is not known how long the phase of inflation lasted for, and that means it is not a good way to calculate the size of the observable Universe, by taking full account of Inflation Theory!
What triggered this violent phase of expansion is still uncertain and the idea behind inflation is that the energy is locked up in space, but this is not fully understood, at least not yet!
The Universe is thought to have gone through a transition where this energy was released, like the melting of ice which releases energy in the phase transition from solid to liquid, and this drove the violent expansion of inflation.
The rapid expansion cooled down the other contents of the Universe (compressing gases heats them up) and then at the end of the inflation period, the energy released from inflation, stopped driving the expansion, and instead went into heating the rest of the contents of the Universe back up again.
This phase at the end of inflation is known as reheating, and the exact timing of how long inflation lasted from, and what brought it to an end, depends on the details of the phase transition.
Inflation hasn’t been proved yet, but it hasn’t been disproved yet either, which is a good sign, thus NASA do use it to make specific predictions about fluctuations, and the next big test is a particular type of light called polarized light from the CMB.
Regardless of how the phase transition worked, there are relationships predicted by inflation, between structures in polarized and unpolarized light.
The Great Exhibition at Crystal Palace in 1851 Attracted 6 Million Visitors
Queen Victoria was responsible for many countries attached to the British Empire and in 1851 the Great Exhibition organised by her husband displayed artefacts, inventions and machines from all of these places across the world.
Prince Albert, who was born in Germany, took a special interest in helping people learn. He was responsible for the Great Exhibition Committee, thus he made the decision that Hyde Park (belonging to the Queen) was to host the greatest show on Earth.
Designed by Joseph Paxton, the building for this wonderful celebration was to be only temporary and nicknamed the Crystal Palace because of the amount of glass used. Paxton was the royal architect partly responsible for the gardens, buildings and greenhouses belonging to the Duke of Devonshire; this gave him the experience and ideas required for these wonderful shards of glass.
100,000 exhibits from 50 countries arrived in London: steam powered machines, tiny glass buttons and a vase made from lard were but a few. Queen Victoria herself officially opened the extravaganza, where reusable tickets cost £3 each or as little as one shilling for the day.
After 6 months, this amazing palace made of glass was moved to Sydenham where it sadly burned to the ground in 1936. However, the huge financial success of the wonderful Great Exhibition paid towards other museums in London and children continue to learn – even today – about Victorian England’s most symbolic display.
Queen Victoria described her husband’s festival of artefacts as “beautiful and fairy like” in her diary. It took 2000 people over a year to build the magnificent palace which eventually had 6 million visitors and it was Thomas Cook who organised trips from all over England to the Great Exhibition making his company very successful.
When the Crystal Palace fell into disrepair it was converted to HMS Victory and used for naval training in the First World War before becoming the very first Imperial War Museum.
Crystal Palace has its own railway station and has become successful once again having brought many visitors back for all types of entertainment: concerts, firework displays, fairground attractions, fishing, the museum and many children’s facilities are available.
Having a football club, athletics stadium and sports complex named after it, Crystal Palace attracts people from all over the world who still travel to this geographical high point in London that is identifiable by the tower used to transmit television signals and to direct aircraft from the top of Sydenham Hill.
Crystal Palace will truly remain one of London’s great open spaces because it also has very diverse horticulture and ornithology stretching right across the park.