‘A Short History of Nearly Everything’ by Bill Bryson

Bill Bryson’s ‘A Short History of Nearly Everything’ is basically a book which, as the title would suggest, covers the fundamentals of science- namely physics. From the formation of the universe to mankind’s slow grasping of its workings, Bryson covers about as much material as he physically (pun intended) could in 500 pages.

The amount of ground covered is impressive: Bryson explores our own planet and get to grips with the ideas, first of Newton and then of Einstein, that allow us to understand the laws that govern it. Then biology holds centre-stage (unfortunately), discussing the appearance of big-brained bipeds and Charles Darwin’s theories as to how it all came about. Despite the fact that both physics and biology are discussed, they are not dealt with separately but for the most part, explored together.

One aspect I particularly enjoyed was that unlike other science books I have previously read, Bryson (who is primarily a travel writer) manages to weave humour into the book so as to break up the information overload. His informal tone also means that it’s never boring (not that physics ever is) but engaging and entertaining throughout.

Whilst discussing difficult concepts, Bryson discusses the history of how they came about, often making the ideas themselves easier to grasp. We learn, for example, of the Victorian naturalist, Francis Trevelyan Buckland, whose scientific endeavours included serving up mole and spider to his guests; and of the Norwegian palaeontologist who miscounted the number of fingers and toes on one of the most important fossil finds of recent history and wouldn’t let anyone else have a look at it for more than 48 years.

Another interesting aspect of the book was Bryson’s quashing of famous scientific myths. The nonsense of Darwin’s supposed “Eureka!” moment in the Galapagos, when he spotted variations in the size of finch beaks on different islands, is swiftly dealt with. As is the idea that palaeontologist Charles Doolittle Walcott made the extremely lucky discovery of the fossil-rich Burgess Shales after his horse slipped on a wet track.

The physics in the book is actually almost glamorous: the sheer improbability of life, the incomprehensible vastness of the cosmos, the overwhelming smallness of elementary particles, and the mysterious counter-intuitiveness of quantum mechanics. He tells us, for example, that every living cell contains as many working parts as a Boeing 777, and that prehistoric dragonflies, as big as ravens, flew among giant trees whose roots and trunks were covered with mosses 40 metres in height. It all sounds very impressive. The book is fairly content heavy so is tough going at parts, but I find it hard to imagine a better simple guide to the universe and its infinite mysteries. The problem: it’s only five sixths physics.

Advertisements

Dark Energy and Dark Matter

In the 1990s physicists were developing ideas about the current size and the rate of expansion of the universe. There were 2 realistic possibilities regarding expansion. One suggestion was that the universe possessed enough energy density (amount of energy stored in a given space) to stop expanding and recollapse (a ‘Big Crunch’), ending up as a single black hole whereby another big bang would recreate the universe. The other possibility was that the universe had the necessary energy density to never stop expanding. http://hubblesite.org/hubble_discoveries/dark_energy/de-fate_of_the_universe.php While there was much debate between these 2 ideas, physicists agreed that gravity was inevitably slowing down expansion. Any mass in the entire universe has a force of gravity acting upon it due to the fact that all gravitational fields technically expand forever. Scientists believed that this force of gravity was pulling all matter in the universe together and thereby was slowing expansion. However, in 1998, physicists began to observe distant supernovae through the Hubble Telescope and discovered that expansion was actually speeding up. That threw a spanner in the works.

Universe Dark Energy-1 Expanding Universe

Dark Energy

If it’s not gravity which is pulling the universe apart then what is? Due to Einstein’s theory of relativity and his equation E=mc2, we know that matter and energy are interchangeable; merely different forms of the same thing. This is why all masses have a gravitational field force: they all consist of matter and therefore energy. So if some unknown energy is pulling apart the universe it must be some form of matter (or radiation). Yet we are suggesting that in space, even when there is no matter or radiation, there is some energy. The most popular theory for this solution is called the cosmological constant. This suggests that a constant energy density is filling space: when the universe expands and new existence is created, an energy force fills this new space. Physicists have coined this energy ‘dark energy’ and it is believed to make up 68.3% of the universe.

(Famously, Einstein described his belief that the Universe has a ‘cosmological constant’ of 0 as the greatest blunder of his career)

Dark Matter

Dark matter is believed to make up 26.8% of the universe. Dark matter (as the name suggests) cannot be seen: it neither emits nor absorbs light, nor any other electromagnetic radiation. Its existence and its properties are inferred from its gravitational effects on visible matter (which makes up a mere 4.9% of the universe). Again, as the name suggests, dark matter is different to dark energy as it consists of matter and mass. In studying the gravitational field lines between massive astronomical objects, astrophysicists have deduced that some matter must be making up for the apparent discrepancies observed. The numbers simply do not add up: something else must be contributing to the mass of the universe, something we cannot see.  According to cosmologists, dark matter is composed of a subatomic particle which has not yet been categorised. The search has begun.

(A supernova like the ones that helped physicists discover the universe’s expansion was accelerating)

Sources:

hubblesite.org

wikipedia.com

science.nasa.gov

bbc.co.uk

Dr Andrew Steele’s Superconductors Lecture

At the Royal Institute in London, after a talk on particle physics, Dr Andrew Steele, an experimental physicist, gave a lecture on superconductivity.

2013-10-11 11.19.49

In the early 1900s, physicists began debating what effect cooling might have on the resistance of a material. From laboratory experiments, they knew that the resistance of a material decreased as the temperature the metal was at decreased as well. Experiments began on the metal mercury- the only metal liquid at room temperature. Experimental data proved that when the metal reached a certain temperature it began to ‘super-conduct’- it had no resistance.

The implications of this were enormous- yet perhaps not so exciting as they could have been. When a material has no resistance, power can be transported without any loss of energy as heat. However, the temperature at which this occurred for mercury was -269°C- not extraordinarily useful.

2013-10-11 11.45.57

However, as more research was done, ceramics (copper oxides) were found with much higher transition (superconducting) temperatures. Nowadays, the highest known transition temperature is -140°C. This is important as it is warmer than the boiling point of liquid nitrogen: -196°C, meaning the ceramic can be cooled to superconducting temperatures by cheaply manufactured liquid nitrogen.

2013-10-11 12.08.24 

After a brief introduction, Dr Steele showed us a small piece of ceramic cooled by liquid nitrogen which when placed over a powerful magnet, literally levitates. This happens because when the superconductor is brought near the magnet, a current is induced. Due to the fact that it has no resistance, the current can continue to flow unimpeded. Theoretically this current could flow forever were the conductor never to warm up.

Uses

1) MRI Machines.

Due to their low resistance, superconductors can be used to produce very strong magnetic fields. These can prove very useful for seeing inside things using water molecules. This proves very useful as it allows us to see inside a person’s brain without cutting open their head, which can be both messy and potentially dangerous.

File:BrainMRI3planes.gif

(Courtesy of Mr Reid,  a collection of various objects stuck to  MRI machines: http://www.simplyphysics.com/flying_objects.html)

2) The Large Hadron Collider

The LHC needed incredibly strong magnets to manipulate protons round the circular circuit at CERN. The only way to provide this magnetic force is by using superconducting magnets. The tiny mass and very high speeds of the protons mean that a large force is required to alter their paths.

3) Power Supply

Transferring power in superconducting cables is incredibly cost efficient as there is no energy lost as heat. In Long Island, New York, a power station is providing a local area with superconducting, highly efficient cables. The difficulty in large scale usage is cooling the cables and protecting the ceramic from breaking.

4) Nuclear Fusion

Nuclear reactors can use magnetic fields (induced by superconductors) to confine plasma to a circular region and provide perfect conditions for nuclear fusion. This is very exciting for physicists as it means power could potentially be produced very cheaply and transported with minimal loss of energy. The only thing holding back development of nuclear power is funding. Many people see the word NUCLEAR and run for the hills, when in actual fact the word just means ‘relating to the nuclei of atoms’.

5) Maglev Trains

Maglev derives its name from MAGnetic LEVitation and utilises the effect mentioned earlier. If a superconductor is cooled to a superconducting temperature when in a magnetic field, a current is induced and the magnet ‘memorises’ its position in the field meaning it will not move horizontally or vertically out of the field. This is called flux pinning and currently is being used in Japan.

LINKS:

Dr Steele on Magnetic Levitation: http://www.youtube.com/watch?v=mAkFr8ZYthw

His website: http://andrewsteele.co.uk/

Black Holes

Some independent research from one of our RGS Physics pupils:

Black_Hole_Milkyway

The first thing to consider when discussing black holes is the question of exactly what they are. Scientifically, a black hole is defined as ‘A region of space having a gravitational field so intense that no matter or radiation can escape.’

Black holes form when a given mass is compressed within a certain volume. When a large mass fills a very small volume, its density becomes very great due to the equation DENSITY=MASS/VOLUME. When an object becomes dense enough, its gravitational field force becomes so great that not even light can escape.

The exact volume any given mass must be compressed into in order to have the necessary density to become a black hole is called its ‘SCHWARZSCHILD RADIUS’ named after the German physician Karl Schwarzschild. The earth’s Schwarzschild radius is about the size of a peanut.

So what might happen if you were to fall into a black hole?http://www.spacetimetravel.org/expeditionsl/expeditionsl.html  (We’ll work under the presumption that you’re wearing an incredible suit which renders all of the dangers of space completely harmless eg. extremities of temperature, lack of oxygen) The first major point of interest you will reach is called the PHOTON SPHERE. At this exact point upon approaching a black hole, the gravitational field strength of the black hole is just perfect such that light can neither escape from nor be sucked into the hole: instead, light orbits it. At this point in the universe you could theoretically do something which no one on earth has ever done: seen the back of their own head without a mirror. This is because light which reflects off the back of your head orbits the entire black hole and returns to your eye.

The next point of interest is called the EVENT HORIZON. Very basically this is the point of no return. Your eventful and law-defying journey has come to its inevitable climax. Let’s say you’ve brought a friend along to accompany you. When your friend sees you cross the event horizon, they will not in fact see you sucked into the black hole to disappear forever. They will see you actually appear to slow down as you approach it and then freeze upon crossing. Slowly your friend will see your body become more and more REDSHIFTED (red) until it eventually disappears. This is because once you cross the event horizon, light can no longer escape: your friend simply cannot see you any more.

For you however, your journey would continue. Until, unfortunately and inevitably, the incredible gravitational field force of the black hole begins to have more effect on the parts of you close to the hole’s centre than those parts furthest away: you are literally pulled apart in a process called SPAGHETTIFICATION. Try it yourself here :http://hubblesite.org/explore_astronomy/black_holes/encyc_mod3_q16.html

mod3_q16_2

Then what? In truth, nobody knows. Perhaps your individual molecules and atoms would be teleported to another part of the universe through a wormhole?  Perhaps you’ll be crushed into an infinitesimally small volume with an infinite density?   Perhaps you’ll simply disappear into nothingness defying all laws of physics? To be honest, none of these options sounds overly appealing.

SOURCES:

http://hubblesite.org/explore_astronomy/black_holes/

http://en.wikipedia.org/wiki/Black_hole (of course)