The anthropic principle

In his 1988 book ‘A Brief History of Time’ the British theoretical physicist Stephen Hawkins (1942-2018) stated:

‘The laws of science, as we know them at present, contain many fundamental numbers, like the size of the electric charge of the electron and the ratio of the masses of the proton and the electron. … The remarkable fact is that the values of these numbers seem to have been very finely adjusted to make possible the development of life.’

In this post I will talk about the view that the laws of physics, and the properties of the Universe as a whole, are somehow finely tuned to allow our existence. The term ‘anthropic principle’ was coined in 1973 by the Australian physicist Brandon Carter (1942-) to describe this viewpoint. However, these ideas had been circulating for decades beforehand.

Brandon Carter – image from Wikimedia Commons

Since 1973 the ideas behind the anthropic principle have been reviewed in many books, both popular science and those aimed at the more specialised reader. They were developed in detail in a book written in 1986 by the theoretical physicists John Barrow and Frank Tipler called ‘The Anthropic Cosmological Principle’.

 

Background: atoms, the atomic nucleus and the four fundamental forces

Before we go into detail about the anthropic principle it is worth discussing, at a high level, the structure of matter and the fundamental forces which drive the way that everything in the Universe behaves.

All ordinary matter in objects like ourselves, planets and stars is made up of atoms. An atom consists of a central nucleus, which has a positive electric charge, surrounded by a cloud of negatively charged electrons. Atoms are very small, typically around 0.0001 microns in diameter (a micron is a millionth of a metre). However the nucleus, which contains nearly all the mass of the atom, is much, much smaller, typically around 0.000 000 001 microns in diameter.

The nucleus consists of a number of protons, which have a positive electric charge and neutrons which have no electric charge. Because the electrons have a negative charge, and the number of protons and electrons in an atom is always the same, atoms have a net charge of zero.

  • The number of protons in the nucleus is called the atomic number and determines the atom’s chemical properties. You may remember from high school chemistry that the atomic number gives the position in the periodic table.
  • The number of neutrons in the nucleus does not affect the chemical properties of the atoms. In fact, all elements have different versions of themselves called isotopes, which have a different numbers of neutrons but the same number of protons.

The simplest possible atomic nucleus is that of hydrogen, which consists of a single proton.  Ordinary hydrogen atoms have no neutrons, but a small fraction of naturally occurring hydrogen atoms are deuterium or heavy hydrogen which have one proton and one neutron. Atoms which have 2 protons (regardless of the number of neutrons) are helium atoms, those which have 3 protons are lithium atoms and so on.  The element with the highest atomic number which naturally occurs on Earth is uranium, which has 92 protons.

 

Carbon

 

An atom of the most common isotope of carbon has 6 protons and 6 neutrons in the nucleus surrounded by 6 electrons. Other isotopes of carbon are found on Earth which have 7 and 8 neutrons in the nucleus.

The Universe is governed by four fundamental forces.  All other interactions, such as the combination of two hydrogen atoms and one oxygen atom to form a water molecule, are due to these fundamental forces.

  • Gravity – an attractive force which acts on all particles having mass.
  • Electromagnetic force – This only acts on electrically charged particles and can be an attractive or repulsive force. If two particles have the same charge, such as two protons, the force is repulsive. If two particles have different charges, such as a proton and an electron, the force is attractive.

  • Strong force – this force acts on fundamental particles called quarks.  There are six types of quark, which have the rather odd names of up, down, charm, strange, top, and bottom.
    • a proton consists of two up quarks and a down quark
    • a neutron consists of one up and two down quarks

Internal structure of a proton – image from Wikimedia Commons

Because protons and neutrons are made up of quarks they too are acted on by the strong force. The force between protons and neutrons which is sometimes called the ‘residual strong force’ or ‘nuclear force’ only works over extremely short ranges, of less than 2.5 femtometres, where 1 femtometre (fm) is one thousand trillionth of a metre. It is this nuclear force which binds protons and neutrons together into atomic nuclei. For more details on the strong force see the notes at the bottom of this post.

  • Weak force – this acts over a short distance, 0.01 fm to 0.1 fm. It is this force which is responsible for a particular type of radioactive decay called beta decay. Without the weak force there would be insufficient oxygen produced in stars to support life (Clavelli 2008).

In addition to these four forces there are other fundamental parameters such as the  mass of the proton and electron and the average densities of ordinary matter, dark matter and dark energy in the Universe. (See my previous posts for more information on dark matter and dark energy.)

Fine tuning

One thing that is apparent is that the relative strength of the four forces (and other  fundamental parameters such the density of matter in the Universe) appear to be finely tuned to enable the production of stars, planets and the eventual evolution of intelligent life. If they were only slightly different, the Universe would be a very different place and life would never emerge. To illustrate this I’ll give some examples below.

  • Hydrogen is the most common element in the Universe. In the early Universe 10 to 1000 seconds after the Big Bang, when it was at a temperature of billions of degrees, about 25% of the primordial hydrogen was converted to helium by nuclear fusion. If the strong interaction had been only 2% stronger than its current value then all its hydrogen would have been converted to helium in the first few minutes of the Universe’s existence. There would be no hydrogen compounds in the Universe, such as water which is, as far as we know, essential for life.
  • If the strong interaction were only a few percent weaker, then deuterium (heavy hydrogen) would not be stable. This would mean that certain elements essential for life such as nitrogen and phosphorous, which are made in the centre of stars by nuclear reactions which fuse deuterium with other nuclei, would not be formed to any appreciable degree.
  • If the electromagnetic interaction were three times stronger, and all other forces the same strength, then any element heavier than carbon (atomic number = 6) could not form. For these elements, the repulsive electromagnetic force between the protons in the nucleus would be stronger than the attractive nuclear force holding the nucleus together. Therefore elements such as nitrogen and oxygen on which life is based would not exist.

  • If gravity were a thousand times stronger, then stars would be much smaller and burn their nuclear fuel more quickly. Instead of living for ten billion years, a typical star would live for about 10 million years.  As readers of a previous post will recall, it took hundreds of millions of years from when the Earth was formed until the emergence of the first single-celled lifeforms. So, in a Universe with stronger gravity, these mini-suns and would have stopped shining before even the first steps in evolution had started.

  • If the strength of all the forces were the same, but there were much less matter in the Universe, then the way the Universe evolved would have been very different. In our Universe, initial unevenness in the distribution of matter in its early stages eventually became the structures such as stars and galaxies which we see today. If the density of ordinary matter were 10% of its current value, then structures such as stars and galaxies would not have formed.

The strong and weak anthropic principles

In his 1973 work Carter distinguished between the strong anthropic principle (SAP) and weak anthropic principle (WAP).  Since then there have been many slightly different definitions of the WAP. The one below is from Barrow and Tipler (1986):

‘the observed values of all physical  and cosmological constants are not equally probable but they take on values restricted by the requirement that carbon-based life can evolve..’

The WAP is generally accepted by most astronomers. In fact it has been criticised as a tautology – a statement which must be true. For if conditions were very different, so that life couldn’t evolve, humanity wouldn’t be around to observe them. Even so, it is remarkable how finely tuned the Universe is.

Many physicists believe in the multiverse –  a collection of possibly an infinite number of other universes.

In other universes different relative strengths of the fundamental forces might apply, so they would look very different from our Universe  In some of them there might be more or fewer than four fundamental forces, perhaps even more than three dimensions of space. It seems likely that in the vast majority of these other universes conditions are such that life can never evolve.

While the WAP is generally accepted, the SAP is more contentious. The definition given by Barrow and Tipler is as follows:

‘The Universe must have those properties which allow life to develop within it at some stage in its history.’

A variation to this definition was proposed by the physicist John Archibald Wheeler (1911-2008) in 1977, which he called the participatory anthropic principle.

‘Observers are necessary to bring the Universe into being’

What  the SAP is saying is that we cannot have a universe which doesn’t have, or have the potential to have, any observers. In some way the purpose of the universe it to give rise to intelligent observers. The SAP is not generally accepted by most astronomers. One particular criticism of it is that we cannot falsify it by observing a  ‘dead universe’ in which observers cannot exist. This is because other universes are, by definition, unobservable.

Final Anthropic Principle

Even more controversial is the Final Anthropic Principle (FAP). This idea was developed by Barrow and Tipler. They could see little point in having a Universe which has as its purpose giving rise to intelligent observers and these intelligent observers then become extinct. The FAP is defined as follows:

Intelligent information-processing must come into existence in the universe, and, once it comes into existence, it will never die out.

In the final chapter of The Anthropic Cosmological Principle they outline a future of the Universe in which the FAP is true. In this universe billions of years after the Big Bang intelligent carbon-based life (i.e ourselves ) eventually emerges. Over a long period of time as the civilisation develops it evolves into different forms of life, which are more robust and better able to survive the harsh conditions of interstellar travel and the long timescales needed. These new lifeforms will not be carbon based but could be for example intelligent self-replicating robots. The civilisation then spreads to neighbouring stars and eventually spreads throughout the galaxy.

Eventually it spreads to neighbouring galaxies and through the entire Universe. If in the far future, the Universe’s expansion slows down and stops and it starts contracting,  it may end in what is termed a singularity of infinite density where the Universe will come to an end and space and time will cease to exist. Barrow and Tipler called this point in time the Omega Point.

At the Omega Point life will have gained complete control of the Universe and will be able to process an infinite amount of information. The final two sentences of The Anthropic Cosmological Principle state:

‘At the instant the Omega Point is reached, life will have gained control of all matter and forces not only in a single universe, but in all universes whose existence is logically possible; life will have spread into all spatial regions in all universes which could logically exist, and will have stored an infinite amount of information, including all bits of knowledge which it is logically possible to know.  And this is the end’

In general the scientific community reacted with scepticism to the FAP.  To many it smacks of pseudo-science. In a review of The Anthropic Cosmological Principle the American science writer Martin Gardner (1914-2010) called it a ‘Completely Ridiculous Anthropic Principle’ which he suggested should be abbreviated to CRAP. In addition, although in the 1980s many astronomers believed in a Universe which wold would eventually collapse into singularity, as discussed in a previous post, this is not supported by current observations. The general consensus is that we live in a Universe which will expand forever and so there will be no Omega Point.

 

Notes

Although there are six types of quarks up, down, charm, strange, top, and bottom, which are sometime called ‘flavours of quark’, only the up and down quarks are found in nature. The other four flavours rapidly decay into either an up or down quark. Interestingly quarks are never found free but always in combination with other quarks. The combinations are:

  • mesons which consist of one quark and one antiquark
  • baryons which consists of three quarks or three antiquarks

The strong force, which acts on quarks because they have a property called colour charge, is carried by particles called gluons.  Gluons also have colour charge and so are subject to the strong force too. For a non-technical overview of the strong force see the following:

https://www.livescience.com/48575-strong-force.html

Reference

Clavelli, L. (2008) Problems in a weakless universe, Available at: https://www.researchgate.net/publication/2020939_Problems_in_a_weakless_universe(Accessed: 24 May 2018).

A Christmas gift from The Science Geek 2017

 

Christmas is almost upon us. Once again I’m offering my e-books for free during the first five days of December!  Just call me Father Christmas :-).

Is Anyone Out There?” is about the likelihood of there being extraterrestrial intelligent life.  It is based on a number of posts from my blog.  For readers based in the UK the book is available to download from Amazon in Kindle format by clicking here and for readers in the US by clicking here. If you’re based outside the UK or US , see the notes at the end of the post.

Is Anyone Out There Cover

The Moon” is also based on a series of posts from my blog and you can guess what it is about.  UK readers download here, US readers here and anyone else please see the notes below.

Moon Cover

How to download the books if you’re based outside the UK or US.

There are threeways of doing this.

Option 1 if you go into the Amazon Kindle store and search for “The Science Geek” as the author you should find my books.

Option 2  I have created a page on my website where you will be able to download either of books for free.
https://thesciencegeek.org/e-books/

I’ll put them there until at least the end of the year.

Option 3  If your country is listed below, I have added some links  to allow you to download the books by just clicking on the link for your country.

Is There Anyone Out There?

Australia http://www.amazon.com.au/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B0131LVNW8?*Version*=1&*entries*=0

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Japan http://www.amazon.co.jp/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B0131LVNW8?*Version*=1&*entries*=0

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USA http://www.amazon.com/gp/product/B0131LVNW8?*Version*=1&*entries*=0

The Moon

Australia http://www.amazon.com.au/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Canada http://www.amazon.ca/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

France http://www.amazon.fr/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

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India http://www.amazon.in/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Italy http://www.amazon.it/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Japan http://www.amazon.co.jp/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Netherlands http://www.amazon.nl/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

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USA http://www.amazon.com/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

A Christmas present from The Science Geek

 

Now that we are into December, Christmas is almost upon us. So, as I did last year, I’d like to give my readers an early Christmas present, by letting you download my short e-books for free during the first five days of December!

Is Anyone Out There?” is about the likelihood of there being extraterrestrial intelligent life.  It is based on a number of posts from my blog.  For readers based in the UK the book is available to download from Amazon in Kindle format by clicking here and for readers in the US by clicking here. If you’re based outside the UK or US , see the notes at the end of the post.

Is Anyone Out There Cover

The Moon” is also based on a series of posts from my blog and you can guess what it is about.  UK readers download here, US readers here and anyone else please see the notes below.

Moon Cover

How to download the books if you’re based outside the UK or US.

There are two ways of doing this.

Firstly, if you go into the Amazon Kindle store and search for “The Science Geek” as the author you should find my books.

Secondly, I have added some links below to allow you to download the book by just clicking on the link for your country.

Is There Anyone Out There?

Australia http://www.amazon.com.au/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Canada http://www.amazon.ca/gp/product/B0131LVNW8?*Version*=1&*entries*=0

France http://www.amazon.fr/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Germany http://www.amazon.de/gp/product/B0131LVNW8?*Version*=1&*entries*=0

India http://www.amazon.in/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Italy http://www.amazon.it/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Japan http://www.amazon.co.jp/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Netherlands http://www.amazon.nl/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Spain http://www.amazon.es/gp/product/B0131LVNW8?*Version*=1&*entries*=0

USA http://www.amazon.com/gp/product/B0131LVNW8?*Version*=1&*entries*=0

The Moon

Australia http://www.amazon.com.au/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Canada http://www.amazon.ca/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

France http://www.amazon.fr/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Germany http://www.amazon.de/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

India http://www.amazon.in/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Italy http://www.amazon.it/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Japan http://www.amazon.co.jp/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Netherlands http://www.amazon.nl/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Spain http://www.amazon.es/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

USA http://www.amazon.com/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Short post of the month February 2016 – gravitational waves

The subject of February’s short post of the month is gravitational waves. These were predicted by Albert Einstein back in 1916, and after decades of searching have finally been detected. In an announcement made on 11 February at a Washington DC press conference David Reitze, the executive director of the LIGO Laboratory, said:

Ladies and gentlemen, we have detected gravitational waves. We did it!”

(Castelvecchi and Witze 2016). Later that day president Obama tweeted his congratulations to the team:

Obama LIGO Tweet

What are gravitational waves?

Gravitational waves are ripples in space time. As gravitational waves pass through an object they cause it to move slightly. The Universe is believed to be awash with gravitational waves, because when massive objects move, such as the Earth orbiting around the Sun, they emit gravitational radiation. However compared to other forms of radiation such as light and radio waves, gravitational waves are very very weak, which is why they have proved so difficult to detect.

Gravitational waves

Image from NASA

The gravitational waves detected were due to the one of most violent events in the Universe, the merger of two black holes, which were rapidly rotating around each other.  Even so, the signal was still incredibly weak

How were they detected?

In the LIGO facility a laser beam is split into two and travels down two 4km tunnels which are at right angles to each other. The two beams then reflect back and forth many times  between two mirrors before they are eventually recombined at an electronic light detector.

Ligo

The apparatus is very finely tuned so that the waves from the two light beams, shown as  A and B in the diagram below, are completely out of phase with each other and as a result cancel each other out completely when they recombine giving no net signal at the light detector C.  Some of you may remember from your high school science lessons this is known as “destructive interference”.

Destructive Interference

When gravitational waves pass through the LIGO facility, the waves cause the tunnels to change their shape by a minute amount.  As a result of this, the distance travelled by each beam of light also changes very slightly, so that they are not completely out of phase and when the beams recombine they no longer completely cancel out. This produces a small signal at the detector.

On 14 September the same signal was found at the two separate LIGO detectors: Livingston in Louisiana first and Hanford in Washington State 7 milliseconds later. The fact that the patterns of the signals were the same and that there was a time delay between the two detections provided the proof that the signals were due to gravitational waves.

LIGO USA

What does this mean for astronomy?

Up until now astronomers have only been able to see the Universe by detecting electromagnetic radiation through telescopes which work at different wavelengths, for example those of visible light, radio waves and x-rays. The instruments at LIGO allow astronomers to observe the Universe in a whole new dimension, in effect to “feel” the Universe vibrating.

That view was reinforced by Stephen Hawking, who in an interview for BBC News (2016) said

“Gravitational waves provide a completely new way at looking at the Universe. The ability to detect them has the potential to revolutionise astronomy. This discovery is the first detection of a black hole binary system and the first observation of black holes merging.”

References

BBC (2016) Einstein’s gravitational waves ‘seen’ from black holes, Available at:http://www.bbc.co.uk/news/science-environment-35524440 (Accessed: 23rd February 2016).

Castelvecchi, D. and Witze, A. (2016) Einstein’s gravitational waves found at last,Available at: http://www.nature.com/news/einstein-s-gravitational-waves-found-at-last-1.19361 (Accessed: 21st February 2016).

 

 

Living on Venus

In this post I’ll look into the distant future and talk about humans living and building settlements on the planet Venus. Because it is well beyond what we can achieve with our current technology, it is a topic that been more in the realm of science fiction rather than factual scientific writing. However, even though there are many difficult obstacles in the way, I think it is very likely to happen at some point in the distant future.

Venus-real

Venus as seen through a telescope – image from NASA.

Why would we want to live on Venus?

There are a number of reasons why humans would want to colonise Venus.  The first three also apply to the Moon, Mars or Mercury.

  • To ensure the continuation of humanity. While the human species is restricted to life on a single planet it is vulnerable to extinction caused by natural or man made disasters.  If humans could live in a self supporting colony outside the Earth then this would provide a Plan B to allow the continuation of our species. Indeed the British physicist Stephen Hawking recently said:

“I believe that the long term future of the human race must be space and that it represents an important life insurance for our future survival, as it could prevent the disappearance of humanity by colonising other planets.”

Stephen Hawkins NASA

Image from NASA

  • To spread human civilisation to other places.  Since humans first evolved, they have constantly sought to expand to new territories. It seems to be almost a biological imperative to find other places to live.  There are not many uninhabited places on Earth, so humans may one day extend their civilisation beyond our planet.
  • To stimulate the economy.  Despite the enormous cost, building colonies outside the Earth would give a huge stimulus to the Earth’s economy. There may well be spin-offs in the same way that the Apollo programme in the sixties and early seventies led to huge technological developments unconnected to space travel.
  • It is relatively easy to get to. Compared to Mars and Mercury, Venus gets closer to the Earth (Williams 2015 a,b). At its closest approach it is 40 million km away from Earth, whereas Mars at its closest approach is still around 80 million km away. It is therefore easier to reach.
  • Larger surface area. Venus is almost the same size as the Earth (ibid). This means that it has almost 4 times the surface area of Mars and 15 times the surface area of the Moon, giving a greater area to colonise.

Earth Venus Mars

  • Similar gravity to the Earth. When astronauts spend long periods of time in a low gravity environment, such as the International Space Station, their bones and muscles weaken. It is not known if the weak gravity on the Moon (16% of the Earth’s gravity) or Mars (38% of the Earth’s gravity) would be sufficient to prevent this happening. The surface gravity on Venus is 91% of that of the Earth which would be sufficient.
  • More solar energy. Any colony would be likely to use solar energy as its main energy source. Venus is closer to the sun than the Earth and receives roughly twice as much solar energy as the Earth. See Notes at the end of this post.

Obstacles

As readers of my previous post will know, Venus is a very inhospitable world. Its surface temperature is on average nearly 500 degrees Celsius and its air pressure is a crushing 92 times that of the Earth. No spacecraft has been able to survive for longer than about an hour on its surface without being destroyed by the intense heat and pressure. The thick atmosphere forms a thermal blanket around the planet. So even at the poles the temperature is not any cooler and, although the temperature drops with altitude, there is nowhere on the planet’s surface which is less than than 380 degrees Celsius. In addition, there is almost no water or oxygen in the atmosphere – both of which are essential for life and Venus does not have a magnetic field to protect the planet from the harmful effects of the solar wind.

Floating cities?

Because the temperature and pressure both fall with altitude there is a region around 50 km above the planet’s surface where both the atmospheric pressure and temperature are similar to that on the Earth.

Venusatmosphere

The graph above shows how the temperature and pressure of Venus’s atmosphere varies with altitude (from Wikimedia Common). 1 Bar is air pressure at sea level on Earth

At this 50 km point, the atmosphere of Venus is the most Earth-like environment, other than Earth itself, in the Solar System. In a paper written in 2008, the NASA scientist Geoffrey Landis suggested building floating cities in the Venusian atmosphere (Atkinson 2008) .  The atmosphere of Venus consists of 97% carbon dioxide, which is denser than the Earth’s atmosphere, which is mainly composed of nitrogen and oxygen. Landis suggested that a large space filled with with breathable air could float high above the Venusian surface in the same way that a helium balloon floats in the Earth’s atmosphere.

Venus Floating City

It would be possible to build large enough spaces for humans to live and work in, although there is the obvious risk that if there were a major leak the entire structure would fall down to the surface to its destruction.

Terraforming Venus

I think that humans will only be able to live on Venus after the entire planet has been transformed to make it more Earth like. This is called terraforming. This process, which is well beyond our current technology, and is at the moment more in the realm of science fiction writers, will involve removing nearly all the carbon dioxide from the atmosphere, adding oxygen, reducing the surface temperature and pressure to similar values to those on Earth, and adding water. It will also be necessary to do something about the long day/night cycles.  A day on Venus lasts 116.8 Earth day which is too long for Earth life to adapt to. (Incidentally, Mrs Geek recently read and enjoyed Karen Thompson Walker’s novel “The Age of Miracles” which describes how humanity struggles to adapt to a world in which the length of a day is much longer than 24 hours.)

In my next post I will discuss how, if humanity doesn’t destroy itself and we become a very advanced civilisation, we could terraform Venus.

The Science Geek

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Notes

Interestingly, the amount of solar energy reaching the surface of Venus is, on average, far less than that reaching the surface of the Earth. This is because, although Venus gets more sunlight, most of the solar energy which hits Venus is reflected back into space by the thick cloud layer high above the planet’s surface. Most of the remaining sunlight is absorbed by the thick atmosphere before it reaches Venus’s surface.  Howver,If Venus is terraformed its surface will get more sunlight than the Earth, because its clouds and atmosphere will be much thinner.

References

Atkinson N. (2008) Colonizing Venus with floating cities, Available at:http://www.universetoday.com/15570/colonizing-venus-with-floating-cities/ (Accessed: 23 Jan 2016).

Williams D R (2015a) Mars fact sheet, Available at:http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html (Accessed: 23 Jan 2016).

Williams D R (2015b) Venus fact sheet, Available at:http://nssdc.gsfc.nasa.gov/planetary/factsheet/venusfact.html (Accessed: 23 Jan 2016).

A Christmas gift from The Science Geek

 

Christmas is almost upon us. Give yourself an early Christmas present, without it costing you a penny, by downloading my e-books for free during the first five days of December!

Is Anyone Out There?” is about the likelihood of there being extraterrestrial intelligent life.  It is based on a number of posts from my blog.  For readers based in the UK the book is available to download from Amazon in Kindle format by clicking here and for readers in the US by clicking here. If you’re based outside the UK or US , see the notes at the end of the post.

Is Anyone Out There Cover

The Moon” is also based on a series of posts from my blog and you can guess what it is about.  UK readers download here, US readers here and anyone else please see the notes below.

Moon Cover

How to download the books if you’re based outside the UK or US.

There are two ways of doing this.

Firstly, if you go into the Amazon Kindle store and search for “The Science Geek” as the author you should find my books.

Secondly, I have added some links below to allow you to download the book by just clicking on the link for your country.

Is There Anyone Out There?

Australia http://www.amazon.com.au/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Canada http://www.amazon.ca/gp/product/B0131LVNW8?*Version*=1&*entries*=0

France http://www.amazon.fr/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Germany http://www.amazon.de/gp/product/B0131LVNW8?*Version*=1&*entries*=0

India http://www.amazon.in/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Italy http://www.amazon.it/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Japan http://www.amazon.co.jp/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Netherlands http://www.amazon.nl/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Spain http://www.amazon.es/gp/product/B0131LVNW8?*Version*=1&*entries*=0

USA http://www.amazon.com/gp/product/B0131LVNW8?*Version*=1&*entries*=0

The Moon

Australia http://www.amazon.com.au/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Canada http://www.amazon.ca/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

France http://www.amazon.fr/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Germany http://www.amazon.de/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

India http://www.amazon.in/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Italy http://www.amazon.it/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Japan http://www.amazon.co.jp/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Netherlands http://www.amazon.nl/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Spain http://www.amazon.es/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

USA http://www.amazon.com/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Is There Anyone Out There? updated post

Thank you to everyone who has downloaded my books. One recent commenter pointed out that the links in the post point to the Amazon UK website and it was unclear how someone based outside the UK would download the books. I have therefore updated the post to make it easier for readers outside the UK to download them.

The Science Geek 🙂

I have written a short e-book on the likelihood of there being extraterrestrial intelligent life and how humans have tried to find that life and make contact with it.  It is based on a number of posts from my blog. For readers based in the UK the book is available to download from Amazon in Kindle format by clicking here. For readers outside the UK, see the notes at the end of the post.

Is Anyone Out There Cover

The book will be free to download until the end of Thursday 13 August GMT, after which time it will be £1.99.

I have also made my earlier e-book on the Moon available on the same deal. For readers based in the UK, this can be downloaded by clicking here.

Moon Cover

How to download the books if you’re based outside the UK.

There are two ways of doing this.

Firstly, if you go into the Amazon Kindle store and search for “The Science Geek” as the author you should find my books.

Secondly, I have added some links below to allow you to download the book by just clicking on the link for your country.

Is There Anyone Out There?

Australia http://www.amazon.com.au/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Canada http://www.amazon.ca/gp/product/B0131LVNW8?*Version*=1&*entries*=0

France http://www.amazon.fr/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Germany http://www.amazon.de/gp/product/B0131LVNW8?*Version*=1&*entries*=0

India http://www.amazon.in/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Italy http://www.amazon.it/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Japan http://www.amazon.co.jp/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Netherlands http://www.amazon.nl/gp/product/B0131LVNW8?*Version*=1&*entries*=0

Spain http://www.amazon.es/gp/product/B0131LVNW8?*Version*=1&*entries*=0

USA http://www.amazon.com/gp/product/B0131LVNW8?*Version*=1&*entries*=0

The Moon

Australia http://www.amazon.com.au/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Brazil http://www.amazon.com.br/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Canada http://www.amazon.ca/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

France http://www.amazon.fr/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Germany http://www.amazon.de/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

India http://www.amazon.in/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Italy http://www.amazon.it/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Japan http://www.amazon.co.jp/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Mexico http://www.amazon.com.mx/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Netherlands http://www.amazon.nl/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

Spain http://www.amazon.es/gp/product/B00WRPR2S4?*Version*=1&*entries*=0

USA http://www.amazon.com/gp/product/B00WRPR2S4?*Version*=1&*entries*=0