The Goldilocks Enigma by Paul Davies (Book Review)

Why is the universe just right for life? Paul Davies spends the duration of his book ‘The Goldilocks Enigma’ answering this relatively open ended question. What is particularly interesting about this book is the fact that much of the questions that are asked are questions that are usually associated with Philosophy and Theology. These questions would then usually be answered with more questions or extremely open ended statements that ultimately lead the reader nowhere. However what is different about Paul Davies is that he is in fact a Physicist who decided he would ask these questions but try and answer them with Physics based theories and concepts.

If you like your space-y type stuff and your astrophysics then this is the book for you, but be warned, if you are a newbie physicist then I would advise you to take this book slowly, very slowly. Davies does not hesitate to dive straight into the theories and explanations of our universe at a reasonably high level from as early as the second chapter. A section I personally found quite interesting was the actual theory of Multiverse and the possibility of multiple (or even infinite) universes explained in a way that was actually reliable and disregarded incorrect misconceptions.  However Davies also ranges from the enormously large to the ever so petite, by explaining what our universe is actually made of down to the smallest of the small, Leptons and Quarks. The metaphors and common day examples he uses to illustrate the most mind boggling of concepts is phenomenal and is a feature that one may struggle to find in other books.

I highly recommend The Goldilocks Enigma to anyone who is looking to broaden their knowledge of general physics but in particular the vast open abyss that surrounds our tiny little rock of a planet.

Live Long and Prosper Yo

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‘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.

‘Paradox; The Nine Greatest Enigmas in Physics’ by Jim Al-Khalili

Paradoxes are notoriously hard to understand but in his book, ‘Paradox; The Nine Greatest Enigmas in Science’, Jim Al-Khalili attempts to describe and explain some of the most common problems that are thought of as paradoxes. This is done on the whole successfully, with Khalili explaining some of the most difficult concepts in modern physics, such as elements of Einstein’s Theory of Relativity, in a way that is relatively easy to understand, although rereading is often required.

One ‘paradox’ that I particularly enjoyed reading about was Olbers’ paradox. This is one way to prove that the universe had a beginning. It starts with a seemingly simple question: why does the sky get dark at night? When this questions different theories were put forward to explain why the night sky wasn’t brighter than the day’s sky as light should be coming from stars in all directions. Some scientists thought that the darkness was the wall of the universe, others thought that the further away stars were too faint to see with the naked eye. The conundrum can only be resolved when you consider the possibility that the universe had a beginning (when the problem was solved the big bang was only a theory, as it still is). The universe is expanding and so the light that is travelling from the most distant stars has not reached us yet and the stars themselves are travelling further away from us. Therefore light does not reach us from all directions, and the night’s sky is dark.

‘Paradox’ is a very good and very interesting physics book and it is mostly understandable. Some passages do need to be reread in order to grasp some of the more complex theories and concepts but the language is both clear and simple. I would recommend this book to almost anyone who wants to learn more about physics in order to broaden their knowledge, rather than just learning in the classroom. Having said this I would recommend having a basic knowledge of quantum physics, even if it is just knowing what Schrödinger’s cat is.

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

Supernovae

The Crab Nebula formed from a supernova. http://upload.wikimedia.org/wikipedia/commons/0/00/Crab_Nebula.jpg

Supernovae are the explosions of stars at the of their life span and are the reason black holes, neutron stars and nebulae, like the crab nebula pictured above form. They can be separated into type I and type II supernovae depending on a number of factors.

Type I supernova:

Type I supernovae occur when a star in a binary system becomes a white dwarf star at the end of its life cycle whilst the other star in the binary system is beginning the process of forming a red giant. When the formation of the red giant occurs it spills gas onto its white dwarf companion in the binary system. If the white dwarf is able to obtain enough mass during the process of the red giant spilling gas onto it and it is able to reach the Chandrasekhar limit of 1.44 solar masses ( 1 solar mass being the mass of the sun), then the white dwarf will collapse into a type I supernova.

Alternatively a type I supernova can occur when both stars are white dwarf or one is a neutron star so long as one of the dwarf stars is able a to accrete mass then when it reaches 1.44 solar masses it will become a supernova. However this process of forming a type I supernova takes much longer which is why Perlmutter described it is a “slow, relentless approach to a cataclysmic conclusion”.

http://www.pha.jhu.edu/~bfalck/SeminarPres.html

If you are still having trouble picturing what happens during a type I supernova imagine a balloon being filled with air until no more air can be forced into the balloon and it pops, or if you want a more visual representation search Monty Python Mr Creosote on youtube.

Type II supernova:

Type II supernova occur when massive stars swiftly and uncontrollably collapse. These stars must be at least 8 times the mass of the sun. Due to their huge mass stars of type II supernova size are able to perform nuclear fusion on elements heavier than hydrogen and helium like our sun, but when they start fusing iron and nickel there is no net energy output so the core of the star becomes inert, because of this that the star is not able to produce any heavier elements and the iron and nickel core continues to grow right up to the Chandrasekhar limit. When the core reaches the limit the electron degeneracy is not enough to maintain the stellar equilibrium and the star’s gravity causes it to catastrophically implode. The outer layers of the star are accelerated at 23% of the speed of light towards the core whilst the core reaches temperatures of 100 billion kelvin. During this process reverse beta decay occurs forming neutrons and neutrinos and releasing 10 to the power of 46 joules in about 10 seconds. After this the inward collapse is stopped by the Neutron degeneracy and the implosion is rebounded outwards causing all surrounding stellar matter to reach escape velocity and form a supernova explosion. 

Aftermath:

After a type II supernova one of four things will happen:

1. The explosion will have been so powerful that the stellar mass was scattered so far it could not reform.

2.  The some of the mass remains to form a Neutron star

3.  If the remnants of the star exceeds 3-4 solar masses then nothing can prevent complete gravitational collapse and a black hole is formed. For more on black holes please visit https://rgsphysics.wordpress.com/2013/09/26/black-holes/

4. Nebula can be formed e.g. the crab nebula in the image at the top.

Perhaps the next star to collapse in a super or even hypernova will be Betelgeuse which is visible in our night sky during the winter.

http://www.dailygalaxy.com/my_weblog/2011/08/will-the-giant-star-betelgeuse-go-hypernova.html

References:

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/snovcn.html

http://en.wikipedia.org/wiki/Type_II_supernova

http://en.wikipedia.org/wiki/Supernova

http://scioly.org/wiki/index.php/Astronomy/Type_II_Supernovae

Rock n’ Roll Physics

To start with I will explain how an electric guitar amp works. As you pluck a string on a guitar it vibrates. The pickups in an electric guitar are nothing more than a bar magnet with many coils of string wrapped around it (an electromagnet), much like a generator this electromagnet takes the kinetic energy of the vibrating strings and turns it into electrical energy which goes through some wires out of the guitar into the amp. In the amp signal the energy is again changed from electrical into kinetic in the form of a speaker moving back and forward creating vibrations in the air, we hear this as sound. By tightening the strings and changing the length of them (tuning and placing your finger on a fret) we get different vibrations that create different electrical signals and therefore different sounds.

Electrical Pickup circuit

Sound Waves

As you turn up the volume on a guitar amp you are increasing the amplitude of the sound wave but amps have something that is known as a threshold. A threshold is the point where the amp is trying to output a sound wave of greater amplitude than it is capable of. The result of this is something known as distortion. What happens when trying to output a wave of greater amplitude than the threshold is that it gets clipped, that is the peaks and troughs get cut and form a wave with a flat  at it’s peaks and troughs not a point. These flat sections are the distortion.

Clipping

Originally distortion wasn’t intended but as rock musicians started playing louder and louder the early amps couldn’t handle the volume and gave this effect that has now become an integral part of rock music. One of the earliest recorded examples of distortion was ‘Rocket 88 by Ike Turner and the Kings of Rhythm’ in 1951 where guitarist Willie Kizart used a damaged amp that meant its threshold was lowered further than usual. By the mid-late 1950s guitarists began doctoring amps so increase distortion as a deliberate effect. By the 1970s we had bands such as Deep Purple and Black Sabbath using this effect so effectively that it is now as popular as it is today.

BIBLIOGRAPHY:

http://entertainment.howstuffworks.com/electric-guitar1.htm

http://en.wikipedia.org/wiki/Distortion_(music)

http://en.wikipedia.org/wiki/Clipping_(audio)

The physics of flight

Some independent research from one of our RGS Physics pupils:

How is it possible that a 568Tonne pressurised metal tube can become airborne and fly half way across the world?

http://en.wikipedia.org/wiki/File:An-225_Mriya.jpg
http://en.wikipedia.org/wiki/File:An-225_Mriya.jpg

Basically, a plane stays in the air due to a balance of forces. The main forces acting on an aircraft are:

  • Thrust, weight, lift and drag.

To keep the plane flying straight and level, all of the four forces must be equal. (Drag=Thrust), (Lift=Weight). If these forces become unbalanced then the aircraft will change its flight profile and will either change its pitch and altitude or speed.

But how does a plane get into the air in the first place?

That is explained by the Bernoulli Principle. The Bernoulli Principle states that an increase in flow results in a decrease in pressure. This means the faster (the air) moves around the wing, the lower pressure it will have.

An aerofoil (or wing) is shaped in such a way that the air particles travel both underneath and above the wing. The curved top of the aerofoil means that the air has to move faster over the top of the wing to reach the same point as the air going beneath the wing. This is an increase of flow for the air particles travelling above the wing. Going back to Bernoulli’s Principle, we know that an increase in flow gives us a lower pressure. So we have a lower pressure on the top of the wing surface and a higher pressure below the wing. This means, that when the pressure difference is greater than the weight /gravity the plane will move up into the air. In the airline industry this is called ‘unsticking’.

So how do we know how much force is needed to overcome the weight/gravity? This is explained by Newton’s Second Law; F=ma. A body of mass (m) subject to a force (F) undergoes acceleration (a).