Though what he really said is open to doubt, the nuclear physicist Enrico Fermi gave his name to a short and possibly final argument against the existence of intelligent life on other planets. There are 200 billion stars in our galaxy alone. 20 billion of these are like our own sun. Let us assume that one in five of these has planets – and we find new exoplanets every year – and let us assume that one in a hundred of these one in five has one planet with liquid water: that gives us 40 million Earth-like planets. I will not carry on with the assumptions, but it seems reasonable that there should be around a hundred thousand other advanced civilisations in our galaxy alone.
This being so, the “Fermi Paradox” asks, where are they? So many other civilisations – so many of them presumably older and more advanced than our own – and they have not visited us. Nor, after generations of scanning with radio telescopes, have we detected any unambiguous signals from them. Either intelligent life on other planets does not exist, or it is so rare and so far apart in time or distance or both, that we shall never find it.
Writing in 2008, Nick Bostrom of Oxford University takes the argument to conclusions that are either depressing or exhilarating. He proposes a set of Great Filters, each of which limits the emergence of intelligent and technologically-advanced life. The most obvious filters are in the past. We shall soon be able to estimate how many planets in our galaxy have liquid water. We still have do not know how life begins. Obviously, it began here. But we have never been able to create a self-replicating organic process in our laboratories. It may be very unusual. It may also be very unusual, once begun, for this process to evolve beyond the very simple. Then it may be very unusual for larger and more complex living structures to evolve, and hardest of all for anything to emerge with the right combination of mind and appendages to enable the birth of a technological civilisation.
Or the Great Filter may be in the future. It may be that civilisations like our own are reasonably common – but that they invariably blow themselves up shortly after finding how to split the atom.
Bostrop’s conclusion is to hope that, when we get there, we shall find that Mars is, and always has been, a sterile rock. Independent life of any kind on a neighbouring planet would suggest a universe teeming with life, and some probability of civilisations like our own. This being so, the lack of contact would put his Great Filter in the future, and would suggest that we are, on the balance of probabilities, heading for self-extinction. No life at all on Mars, now or in the past, would let him keep hoping that the Great Filter is in the past, and that we may have a splendid progress before us.
Sean Gabb, “Do Flying Saucers Exist?”, Sean Gabb, 2020-11-15.
August 1, 2022
QotD: Fermi’s Paradox and the Great Filter(s)
July 26, 2022
Barbarian Europe: Part 4 – The Ostrogoths in Italy
seangabb
Published 10 May 2021In 400 AD, the Roman Empire covered roughly the same area as it had in 100 AD. By 500 AD, all the Western Provinces of the Empire had been overrun by barbarians. Between April and July 2021, Sean Gabb explored this transformation with his students. Here is one of his lectures. All student contributions have been removed.
(more…)
July 23, 2022
Barbarian Europe: Part 3 – Barbarism and Christianity
seangabb
Published 1 May 2021In 400 AD, the Roman Empire covered roughly the same area as it had in 100 AD. By 500 AD, all the Western Provinces of the Empire had been overrun by barbarians. Between April and July 2021, Sean Gabb explored this transformation with his students. Here is one of his lectures. All student contributions have been removed.
(more…)
July 19, 2022
Barbarian Europe: Part 2 – The Fall of Rome
seangabb
Published 22 Apr 2021In 400 AD, the Roman Empire covered roughly the same area as it had in 100 AD. By 500 AD, all the Western Provinces of the Empire had been overrun by barbarians. Between April and July 2021, Sean Gabb explored this transformation with his students. Here is one of his lectures. All student contributions have been removed.
(more…)
July 16, 2022
Barbarian Europe: Part 1 – A Lurking Menace
seangabb
Published 18 Apr 2021In 400 AD, the Roman Empire covered roughly the same area as it had in 100 AD. By 500 AD, all the Western Provinces of the Empire had been overrun by barbarians. Between April and July 2021, Sean Gabb explored this transformation with his students. Here is one of his lectures. All student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blak…
July 8, 2022
The Early Emperors – Part 7: The Imperial Women
seangabb
Published 11 Jan 2022The Roman Empire was the last and the greatest of the ancient empires. It is the origin from which springs the history of Western Europe and those nations that descend from Western Europe. It is the political entity within which the Christian Faith was born, and the growth of the Church within the Empire, and its eventual establishment as the sole faith of the Empire, have left an indelible impression on all modern denominations. Its history, together with that of the ancient Greeks and the Jews, is our history. To understand how the Empire emerged from a great though finally dysfunctional republic, and how it was consolidated by its early rulers, is partly how we understand ourselves.
Here is a series of lectures given by Sean Gabb in late 2021, in which he discusses and tries to explain the achievement of the early Emperors. For reasons of politeness and data protection, all student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blak…
July 1, 2022
The Early Emperors – Part 6: The Birth of Christianity
seangabb
Published 27 Dec 2021The Roman Empire was the last and the greatest of the ancient empires. It is the origin from which springs the history of Western Europe and those nations that descend from the Western Roman Empire. It is the political entity within which the Christian faith was born, and the growth of the Church within the Empire, and its eventual establishment as the sole faith of the Empire, have left an indelible impression on all modern denominations. Its history, together with that of the ancient Greeks and the Jews, is our history. To understand how the Empire emerged from a great though finally dysfunctional republic, and how it was consolidated by its early rulers, is partly how we understand ourselves.
Here is a series of lectures given by Sean Gabb in late 2021, in which he discusses and tries to explain the achievement of the early Emperors. For reasons of politeness and data protection, all student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blak…
June 28, 2022
The Early Emperors – Part 5: Claudius, the First Normal Emperor
seangabb
Published 13 Dec 2021The Roman Empire was the last and the greatest of the ancient empires. It is the origin from which springs the history of Western Europe and those nations that descend from the Western Roman Empire. It is the political entity within which the Christian faith was born, and the growth of the Church within the Empire, and its eventual establishment as the sole faith of the Empire, have left an indelible impression on all modern denominations. Its history, together with that of the ancient Greeks and the Jews, is our history. To understand how the Empire emerged from a great though finally dysfunctional republic, and how it was consolidated by its early rulers, is partly how we understand ourselves.
Here is a series of lectures given by Sean Gabb in late 2021, in which he discusses and tries to explain the achievement of the early Emperors. For reasons of politeness and data protection, all student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blak…
June 21, 2022
The Early Emperors – Part 4: Caligula, The First Insane Tyrant
seangabb
Published 31 Oct 2021The Roman Empire was the last and the greatest of the ancient empires. It is the origin from which springs the history of Western Europe and those nations that descend from the Western Roman Empire. It is the political entity within which the Christian faith was born, and the growth of the Church within the Empire, and its eventual establishment as the sole faith of the Empire, have left an indelible impression on all modern denominations. Its history, together with that of the ancient Greeks and the Jews, is our history. To understand how the Empire emerged from a great though finally dysfunctional republic, and how it was consolidated by its early rulers, is partly how we understand ourselves.
Here is a series of lectures given by Sean Gabb in late 2021, in which he discusses and tries to explain the achievement of the early Emperors. For reasons of politeness and data protection, all student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blak…
June 18, 2022
The Early Emperors – Part 3: Tiberius, A Safe Pair of Hands
seangabb
Published 22 Oct 2021The Roman Empire was the last and the greatest of the ancient empires. It is the origin from which springs the history of Western Europe and those nations that descend from the Western Roman Empire. It is the political entity within which the Christian faith was born, and the growth of the Church within the Empire, and its eventual establishment as the sole faith of the Empire, have left an indelible impression on all modern denominations. Its history, together with that of the ancient Greeks and the Jews, is our history. To understand how the Empire emerged from a great though finally dysfunctional republic, and how it was consolidated by its early rulers, is partly how we understand ourselves.
Here is a series of lectures given by Sean Gabb in late 2021, in which he discusses and tries to explain the achievement of the early Emperors. For reasons of politeness and data protection, all student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blak…
June 14, 2022
The Early Roman Emperors – Part 2: An Empire of Peoples
seangabb
Published 4 Oct 2021The Roman Empire was the last and the greatest of the ancient empires. It is the origin from which springs the history of Western Europe and those nations that descend from the Western Roman Empire. It is the political entity within which the Christian faith was born, and the growth of the Church within the Empire, and its eventual establishment as the sole faith of the Empire, have left an indelible impression on all modern denominations. Its history, together with that of the ancient Greeks and the Jews, is our history. To understand how the Empire emerged from a great though finally dysfunctional republic, and how it was consolidated by its early rulers, is partly how we understand ourselves.
Here is a series of lectures given by Sean Gabb in late 2021, in which he discusses and tries to explain the achievement of the early Emperors. For reasons of politeness and data protection, all student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blake/e/B005I2B5PO
June 10, 2022
The Early Roman Emperors – Part 1: Augustus
seangabb
Published 26 Sep 2021The Roman Empire was the last and the greatest of the ancient empires. It is the origin from which springs the history of Western Europe and those nations that descend from the Western Roman Empire. It is the political entity within which the Christian faith was born, and the growth of the Church within the Empire, and its eventual establishment as the sole faith of the Empire, have left an indelible impression on all modern denominations. Its history, together with that of the ancient Greeks and the Jews, is our history. To understand how the Empire emerged from a great though finally dysfunctional republic, and how it was consolidated by its early rulers, is partly how we understand ourselves.
Here is a series of lectures given by Sean Gabb in late 2021, in which he discusses and tries to explain the achievement of the early Emperors. For reasons of politeness and data protection, all student contributions have been removed.
More by Sean Gabb on the Ancient World: https://www.classicstuition.co.uk/
Learn Latin or Greek or both with him: https://www.udemy.com/user/sean-gabb/
His historical novels (under the pen name “Richard Blake”): https://www.amazon.co.uk/Richard-Blak…
June 3, 2022
The Crusades: Part 10 – The End of the Crusader Kingdoms
seangabb
Published 27 Mar 2021The Crusades are the defining event of the Middle Ages. They brought the very different civilisations of Western Europe, Byzantium and Islam into an extended period of both conflict and peaceful co-existence. Between January and March 2021, Sean Gabb explored this long encounter with his students. Here is one of his lectures. All student contributions have been removed.
(more…)
May 31, 2022
The Crusades: Part 9 – The Other Crusades
seangabb
Published 18 Mar 2021The Crusades are the defining event of the Middle Ages. They brought the very different civilisations of Western Europe, Byzantium and Islam into an extended period of both conflict and peaceful co-existence. Between January and March 2021, Sean Gabb explored this long encounter with his students. Here is one of his lectures. All student contributions have been removed.
(more…)
May 27, 2022
The Crusades: Part 8 – The Rise of Venice
seangabb
Published 12 Mar 2021The Crusades are the defining event of the Middle Ages. They brought the very different civilisations of Western Europe, Byzantium and Islam into an extended period of both conflict and peaceful co-existence. Between January and March 2021, Sean Gabb explored this long encounter with his students. Here is one of his lectures. All student contributions have been removed.
(more…)
