Archive for the ‘Space’ Category

Beware the Ides of March

March 15, 2016

That is what a soothsayer says to Julius Caesar in Shakespeare’s play. Caesar had reason to be wary of that particular date since that was the day the conspirators planned to assassinate him. Caesar ignored the warning, either out of fatalism or foolhardiness, and his assassination began the course of events that led to the rise of his grand-nephew Augustus and the end of the Roman Republic.

But what are the ides anyway? The Roman calendar was somewhat complicated and was reformed several times in the history of the Republic, until Julius Caesar straighten things out with his Julian calendar. Originally, the Roman calendar seems to have been a lunar calendar with the months corresponding to the lunar cycle. Thus each month began with the New Moon. The Romans did not count days from the beginning of the month, as we do, but instead counted before and after certain key days perhaps corresponding with the phases of the moon. The first day of the month corresponding with the new moon was called the Kalends, from which our word calendar is derived. The ides of the month was the day in the middle of the month, corresponding to the full moon. The ides was either on the thirteenth or fifteenth day depending on whether the month was a long or short one. The nones was eight days before the ides and corresponds to the half moon or first quarter. I would think that they would also make the third quarter of the moon one of the special days but it doesn’t seem to have been.

The day before the kalends, nones, or ides was referred to as the pridie, or the day before in Latin. So, yesterday, March 14, was pridie ides March. Other dates were simply counted back from the nearest reference day. So March 12 would be the the fourth day, ( the reference days were counted) before the ides of March, or a.d. (ante diem) IV id March. March 2 was six days before the nones or a. d VI non. March 25 would be 8 days before the kalends of April, or a. d. VIII kal. This seems to be a rather cumbersome system, having to remember how many days between the kalends and ides, etc, but I suppose the Romans were used to it, and maybe it wasn’t much worse than having to remember which months have thirty or thirty-one days. I’m glad we don’t do that though.

In any case, today is the Ides of March, so if you happen to be Julius Caesar, watch out.

Leap Day 2016

February 29, 2016

Since today, a leap day, occurs only once every four years, I thought I might like to write a little about why we have leap years and where the idea originated. Our calendar ultimately comes from the calendar used by the Romans. The names of the months and the number of days in each month are basically the same, though the year originally began in March and the Romans did not count the days from the beginning of the month but counted backwards from three fixed days, the kalends, the nones, and the ides.

The Roman calendar was, like many ancient calendars, a lunisolar calendar with a intercalary month added at intervals to keep the dates aligned with the seasons. The responsibility for inserting the intercalary month lay with the Pontifex Maximus, the leader of the order of Priests called the Pontiffs. (One of the titles of the Pope is the Pontiff.) Unfortunately this position was a political one and the Pontiffs got in the habit of inserting the extra month to prolong the terms of their political allies, or not inserting it if their enemies were in office. By the time of Julius Caesar the date was three months behind the seasons.

In 46 BC, Caesar returned to Rome from Egypt. The Egyptians had long used a solar calendar of 365 days. Caesar brought mathematicians and astronomers from  Alexandria with him and he directed them to reform the Roman calendar. The calendar they developed is called the Julian Calender. In this new calendar, they changed the first month to January and gave each month the number of days it now contains. Most importantly, they did away with the intercalary months altogether. The Julian calendar was to be solely a solar calendar and the months would have no relation to the moon. Caesar lengthened the year 46 BC to 445 days to bring the date back in alignment with the seasons. This year was called the year of confusion, but it was the last year of confusion as the Julian calendar was adopted throughout the Roman world and is used with some modifications to this day.

The most important reform the Greek astronomers made was the introduction of the Leap Year. The problem is that the year is not exactly 365 days. Instead, as the astronomers had learned, the year is closed to 365 1/4 days. So, it seemed that an easy way to keep the date aligned was to simply add a day every four years. And so, since Caesar’s reform of the calendar, we have had leap years every four years.

Have We Found Aliens?

January 25, 2016

It is just barely possible that we have discovered the first evidence for some sort of extraterrestrial intelligence. At any rate, astronomers have discovered a star that is something of an anomaly, according to this article.

Three months ago, news broke that a giant “alien megastructure” could exist around a bizarre-looking star 1,500 light-years away.

While the prospect of aliens was first launched by Penn State astronomer Jason Wright, almost everyone in the astronomy community agreed that the chances that this was the case were “very low.

Now, the latest investigations into this strange star by Louisiana State University astronomerBradley Schaefer have reignited the alien theory, New Scientist reported.

What makes this star, KIC8462852, so bizarre is the drastic changes in light we see from it over time. Many stars experience temporary fluctuations in brightness, increasing and decreasing in luminosity over time, but KIC8462852’s changes are severe by comparison.

Astronomers refer to stars that experience those fluctuations in luminosity as variable stars. A star can change in brightness either because something occasionally blocks the star’s light, usually a companion star or perhaps a planet, or because the internal processes of the star cause variations in luminosity. Probably every star is at least a little variable. The Sun has its eleven year sunspot cycle, for example. Whether the cause of a star’s variability is external or internal, its cycle of variability tends to be regular. That does not seem to be the case with KIC8462852.

Between 2009 and 2013, astronomers using the Kepler space telescope discovered that it would sometimes lose up to 20% of its brightness. What’s more, the changes didn’t follow any obvious pattern.

That would suggest something gigantic must be blocking the light at random times, meaning that it couldn’t be a planet or other regular orbiting object because that would generate a distinct pattern of dimming light. It must be something that changes shape over time, thereby blocking different levels of light at random intervals.

Could the cause be artificial?

An alien megastructure, called a Dyson swarm, was suggested as one explanation for what scientists have observed, but the most likely reason astronomers came up with was comets — a giant family of them.

But Shaefer says not so fast.

“The comet-family idea was reasonably put forth as the best of the proposals, even while acknowledging that they all were a poor lot,” Schaefer told New Scientist. “But now we have a refutation of the idea, and indeed, of all published ideas.”

To make his discovery, Schaefer had to dig deep down into the astronomy archives at Harvard. It turns out, astronomers have data on KIC8462852 dating back as far as 1890.

By analyzing over 1,200 measurements of this star’s brightness taken from 1890 through 1989, Schaefer found that the irregular dimming of KIC8462852 has been going on for over 100 years. Schaefer published his findings in the online preprint server arXiv.org.

What’s more, he explains in his paper that this “century-long dimming trend requires an estimated 648,000 giant comets (each with 200 km diameter) all orchestrated to pass in front of the star within the last century,” which he said is “completely implausible.”

By killing the comet theory, Schaefer has brought us one step closer to finding out what is really happening around KIC8462852.

At the same time, he’s also reignited the possibility that the source could be an alien megastructure that an advanced alien civilization has been slowly building over time. One thing’s certain for Schaefer: The bizarre dimmings are probably caused by a single, physical mechanism that’s undergoing some type of ongoing change.

“The century-long dimming and the day-long dips are both just extreme ends of a spectrum of timescales for unique dimming events, so by Ockham’s Razor, all this is produced by one physical mechanism,” Shaefer said in his paper. “This one mechanism does not appear as any isolated catastrophic event in the last century, but rather must be some ongoing process with continuous effects.”

Schaefer isn’t the only one interested in learning more about KIC8462852. Late last year, astronomer Doug Vakoch and his team at the new organization called SETI (Search for Extraterrestrial Intelligence) International — not to be confused with the SETI Institute — went hunting for aliens around KIC8462852.

They searched for signals that an alien civilization might be beaming toward Earth either in radio or visible wavelengths, but ultimately they came up empty handed. So, if it is aliens, then they’re being awfully quiet.

Is it aliens? If this is some structure created by an extraterrestrial civilization, we shouldn’t expect to be receiving any sort of messages from them. They would have no reason to believe that there is any intelligent life here on Earth since any radio waves we have emitted cannot be farther than about 100 light years away by now. Any message to or from KIC8462582 would take 1500 years to reach its destination. They may have sent a message last year but we won’t get it for a long time.

I tend to think, however, that the explanation for the strange behavior of KIC8462582 will turn out to be due to an entirely natural phenomenon.I think that as we begin to explore the universe we will find that life is fairly common. The elements and compounds that make up the basic components of life are found throughout the universe and if the current understanding of the earliest history of the Earth is accurate, it seems that life arose on this planet as soon as it was physically possible. Scientists do not know precisely how life began on Earth, but I think that they will find that where ever the right conditions are found, there will be life of some sort. I think, though, that most of the life we find in the universe is going to be simple and primitive, some equivalent of terrestrial bacteria. Bacteria were the only form of life found on Earth for most of its history. Intelligent life must be still rarer. Human beings have only been around much less than 1% of the Earth’s history and we have only had to capability to communicate by radio for a little over a century. There doesn’t seem to be any reason to believe that the development of intelligent life or a technological civilization was inevitable and considering the strange twists and turns of the history of life it  may not be very probable. I think then, that we will find some few worlds with alien plants or animals, but that we are probably the only intelligent form of life in our galaxy.

Even if there are extraterrestrial civilizations, our relations with them will not be like Star Wars or Star Trek in which there are a number of different races at about the same level of technology. It is more likely that if two civilizations make contact, one civilization will be millions of years ahead of the other. Any space wars are likely to be short and decisive with the more advanced civilization quickly overcoming the more primitive. With that in mind, maybe we shouldn’t be trying to draw attention to ourselves. I would hate to think that there is a fleet of conquistadors from KIC8462852 heading this way.

The Nativity According to Matthew

December 21, 2015

 

Matthew begins his Gospel with the genealogy of Jesus. I’ll skip the genealogy and go straight to his account of Jesus’s birth.

 

18 This is how the birth of Jesus the Messiah came about: His mother Mary was pledged to be married to Joseph, but before they came together, she was found to be pregnant through the Holy Spirit. 19 Because Joseph her husband was faithful to the law, and yetdid not want to expose her to public disgrace, he had in mind to divorce her quietly.

20 But after he had considered this, an angel of the Lord appeared to him in a dream and said, “Joseph son of David, do not be afraid to take Mary home as your wife, because what is conceived in her is from the Holy Spirit. 21 She will give birth to a son, and you are to give him the name Jesus, because he will save his people from their sins.”

22 All this took place to fulfill what the Lord had said through the prophet: 23 “The virgin will conceive and give birth to a son, and they will call him Immanuel” (which means “God with us”).

24 When Joseph woke up, he did what the angel of the Lord had commanded him and took Mary home as his wife. 25 But he did not consummate their marriage until she gave birth to a son. And he gave him the name Jesus.

After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, “Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.”

When King Herod heard this he was disturbed, and all Jerusalem with him. When he had called together all the people’s chief priests and teachers of the law, he asked them where the Messiah was to be born. “In Bethlehem in Judea,” they replied, “for this is what the prophet has written:

“‘But you, Bethlehem, in the land of Judah,
are by no means least among the rulers of Judah;
for out of you will come a ruler
who will shepherd my people Israel.’

Then Herod called the Magi secretly and found out from them the exact time the star had appeared. He sent them to Bethlehem and said, “Go and search carefully for the child. As soon as you find him, report to me, so that I too may go and worship him.”Star-of-Bethlehem

After they had heard the king, they went on their way, and the star they had seen when it rose went ahead of them until it stopped over the place where the child was. 10 When they saw the star, they were overjoyed. 11 On coming to the house, they saw the child with his mother Mary, and they bowed down and worshiped him. Then they opened their treasures and presented him with gifts of gold, frankincense and myrrh. 12 And having been warned in a dream not to go back to Herod, they returned to their country by another route.

 

13 When they had gone, an angel of the Lord appeared to Joseph in a dream. “Get up,” he said, “take the child and his mother and escape to Egypt. Stay there until I tell you, for Herod is going to search for the child to kill him.”

14 So he got up, took the child and his mother during the night and left for Egypt, 15 where he stayed until the death of Herod. And so was fulfilled what the Lord had said through the prophet: “Out of Egypt I called my son.”

16 When Herod realized that he had been outwitted by the Magi, he was furious, and he gave orders to kill all the boys in Bethlehem and its vicinity who were two years old and under, in accordance with the time he had learned from the Magi. 17 Then what was said through the prophet Jeremiah was fulfilled:

18 “A voice is heard in Ramah,
weeping and great mourning,
Rachel weeping for her children
and refusing to be comforted,
because they are no more.”

19 After Herod died, an angel of the Lord appeared in a dream to Joseph in Egypt 20 and said, “Get up, take the child and his mother and go to the land of Israel, for those who were trying to take the child’s life are dead.” (Matthew 1:18-2:20)

 

Most people think that the slaughter of the baby boys in Bethlehem involved the murder of hundreds or thousands of innocents. Remember, though, that Bethlehem was a small village in this time with a likely population of a few hundred. It is doubtful that more than half a dozen children were killed, not enough to make it into any other sources we have for Herod’s rule. Herod was certainly ruthless enough to order such a massacre. He had no trouble killing members of his own family if he thought they threatened his rule. In fact, Herod being an Idumean (or Edomite) and not a Jew, was a foreigner and so was as despised by many Judeans as a Roman governor would have been. If he had heard that there was a potential rival to his throne, even a child, that the Jews might rally around, he would have wasted no time in disposing of that rival.

The word Magi usually refers to Zoroastrian priests. In Greco-Roman usage the term Magi had connotations of magicians or sorcerers, exotic figures from distant lands. It is not clear just who the Magi actually were. They may indeed have been Zoroastrians. The references to the Star of Bethlehem suggest that they may have been astrologers. The Babylonians had a reputation for being skilled in astrology and magic so the Magi may have come from Mesopotamia. They may also have been Jewish since they were seeking for a king of the Jews. The fact that they were unfamiliar with the prophets may prove that they were Gentiles. The number of the Magi is not given in the Gospel. The reason that three are usually pictured  is that there were three gifts; gold, frankincense,and myrrh.

strozzi-adoration-magi-NG582-fm

It is also not clear just what the Star of Bethlehem actually was. There have been several theories presented, but none of them are entirely satisfactory. The star might have been a supernova, perhaps in a nearby galaxy. There is no way to know for certain since any supernova remnant so far away would be difficult, perhaps impossible, to detect. It might also have been a comet. This is rather unlikely. Although a comet would behave much as the star is said to behave, hanging in the sky over a certain location for several nights, comets were universally perceived as being harbingers of disaster in ancient, and not so ancient, times. The most likely explanation is a conjunction of the planets Jupiter and Saturn. The astronomer Keppler discovered that there was indeed such a conjunction in the year 7 BC. The following year there was another conjunction of Mars, Jupiter, and Saturn. This might have been very impressive to the Magi. It may also be that the Star was a supernatural phenomonem and one that cannot be studied today. Whatever the truth of the matter is, I hope everyone has a wonderful Christmas.

 

 

 

The Myths Really Happened

December 18, 2015

One of the nice things about reading e-books on a Kindle is that a great many books are available either for free or for a very low price because they are older books whose authors are long dead and the copyrights have expired. These low-priced or free books are some of the greatest classics of literature and naturally I have been interested in reading them, particularly the classical Greek and Roman mythological epic such as Homer’s Iliad and Odyssey and Virgil’s Aeneid. Now I have recently come across a pair of news stories that suggest that the backgrounds of these epic poems may not have come entirely from the minds of the writers, that there may be a kernel of fact behind the fiction.

First, there is this interesting article from the Guardian on some recent research about the mysterious Etruscans who lived and ruled in Italy before the rise of Rome. The Romans themselves were not Etruscans but the Etruscans heavily influenced Roman culture. Unfortunately, the written language of the Etruscans remains undeciphered, so little is known of them, except what the Greeks and Romans have written about them.

They gave us the word “person” and invented a symbol of iron rule later adopted by the fascists. Some even argue it was they who really moulded Roman civilisation.

Yet the Etruscans, whose descendants today live in central Italy, have long been among the great enigmas of antiquity. Their language, which has never properly been deciphered, was unlike any other in classical Italy. Their origins have been hotly debated by scholars for centuries.

Genetic research made public at the weekend appears to put the matter beyond doubt, however. It shows the Etruscans came from the area which is now Turkey – and that the nearest genetic relatives of many of today’s Tuscans and Umbrians are to be found, not in Italy, but around Izmir.

The European Human Genetic Conference in Nice was told on Saturday the results of a study carried out in three parts of Tuscany: the Casentino valley, and two towns, Volterra and Murlo, where important finds have been made of Etruscan remains. In each area, researchers took DNA samples from men with surnames unique to the district and whose families had lived there for at least three generations.

They then compared their Y chromosomes, which are passed from father to son, with those of other groups in Italy, the Balkans, modern-day Turkey and the Greek island of Lemnos, which linguistic evidence suggests could have links to the Etruscans.

The latest findings confirm what was said about the matter almost 2,500 years ago, by the Greek historian Herodotus. The first traces of Etruscan civilisation in Italy date from about 1200 BC.

About seven and a half centuries later, Herodotus wrote that after the Lydians had undergone a period of severe deprivation in western Anatolia, “their king divided the people into two groups, and made them draw lots, so that the one group should remain and the other leave the country; he himself was to be the head of those who drew the lot to remain there, and his son, whose name was Tyrrhenus, of those who departed”.

But the latest conclusions may add weight to a rival, apparently more fanciful, theory that links their name to Troy, the “city of towers” and a part of the Lydian empire. The most likely date for the fall of Troy, as described by Homer, is between 1250 and 1200 BC.

Virgil’s Aeneid tells the story of a Trojan prince named Aeneas who fled with his family when the Greeks destroyed Troy. Aeneas led his followers around the Mediterranean until they settled at last in Italy where after many adventures he established a kingdom. His descendants were Romulus and Remus, the legendary founders of Rome. Virgil wrote the Aeneid in the hope of creating a national epic for the Romans in the same way that Homer’s Iliad and Odyssey were for the Greeks, and he consciously inserted what might be considered political propaganda justifying the leadership of Rome over the known world, and also the role of his patron Augustus Caesar as the first Emperor of the Roman Empire. This does not mean that Virgil simply invented the plot of the Aeneid. Instead, it seems that he made use of Roman legends concerning the Trojan origins of the Roman people that had been told for generations by combining them into a more unified and coherent story.

aeneasmap

The Romans were not themselves Etruscans. They were clearly natives of Italy, closely related in language and culture to many other people living in south and central Italy. The Etruscans clearly influenced the development of Roman culture and it is likely that they brought the alphabet to Italy, as well as many other elements of civilization. If the recent findings about the origins of the Etruscans from Lydia in Asia Minor, the actual location of Troy, then it is possible that the legends that Virgil drew upon to create the Aeneid are a distant memory of a real migration from Asia Minor to Italy, perhaps by refugees fleeing war and the destruction of their homeland.

But what about Homer? Unlike Virgil who lived at around the time of Christ and so is well known to history, Homer lived at a time when Greece was emerging from a dark age. Not much is known about Homer, even whether a poet by that name ever really existed. Homer’s Iliad tells the story of an dispute between Achilles and the other leaders of the Greeks during the Trojan War and of Achilles’s personal feud with the Trojan prince Hector. The Odyssey tells the story of the Greek Odysseus’s trials as he sails home after the war. It wouldn’t seem likely that these fanciful tales are based on real, historical persons, yet, there really was a Troy, or at any rate a city at the legendary location of Troy. This city was burned down several times and rebuilt, but it is not clear whether the Greek stories of the Trojan War are a memory of an actual siege of the city. Still, there is this story I read in the Independent.

The Odyssey is one of the great works of ancient Western literature, written eight centuries before the birth of Christ and four centuries after the fall of Troy. Generations of classicists have pored over the many lines of Homer’s epic description of the long journey taken by the hero Odysseus to his home island of Ithaca. Now two scholars have found evidence to support the idea that one line, in the poem’s 20th book, refers to a total solar eclipse that occurred on 16 April 1178 BC – the day when Odysseus returned home to kill his wife’s suitors. If true, this would date the fall of Troy itself to precisely 1188 BC.

The idea that The Odyssey refers to a total solar eclipse, when the Moon blocks out the Sun completely, is not new. It was first suggested by ancient scholars, but it was only in the 1920s that astronomers were able to calculate that such an eclipse over Greece around that time could only have taken place on 16 April 1178 BC.

 

Instead of looking at when a solar eclipse occurred in history, as other astronomers had done, they investigated the timing of a new moon, the simultaneous appearance of two stellar constellations in the evening sky, and appearances of the planets Mercury and Venus. All four phenomena are mentioned in The Odyssey which gave Constantino Baikouzis of the Observatorio Astronomico de La Plata in Argentina, and Professor Marcelo Magnasco, of the Rockefeller University in New York, another way of checking the date when Odysseus is supposed to have returned to his home on Ithaca to kill his wife’s suitors.

They calculated the pattern in which these four events occurred, from the references mentioned in The Odyssey, and compared them against patterns gleaned from 135 years of astronomical data – nearly 5,000 days. The result was they found just one date that could have been the fateful day. It was the same 16 April 1178BC that was known to have been a total solar eclipse. “What are the chances of having two different ways of dating the text and both agreeing on the same date? We calculated the chances of these two dates agreeing by chance alone is something like one in 50,000,” Professor Magnasco said.

“Not only is this corroborative evidence that this date might be something important but, if we take it as a given that the death of the suitors happened on this particular eclipse date, then everything else in The Odyssey happens exactly as is described.”

“Under the very large assumption that there was an Odysseus, there were suitors that got massacred, that it indeed took 10 years for Odysseus to get back … yes, in that case the fall of Troy would have happened 10 years before the death of the suitors, thus in 1188BC. The current dating of the destruction layer of Troy VIIa is around 1190 plus/minus a few years.”

Obviously the more fantastic elements of Homer’s tales such the cyclops or the miraculous involvement of the gods, but it is altogether possible that the legends of the Trojan War are derived from a real war and the Iliad from an actual incident in that war. The Odyssey may be a dim memory of actual troubles faced by men returning from this war to find matters at home not as they might wish. Who can tell?

OK, this part was probably made up.

OK, this part was probably made up.

The Martian

September 30, 2015

I have just finished reading the most amazing book, The Martian by Andy Weir. Perhaps you have seen the advertisements for the forth-coming movie starring Matt Damon as the Martian of the title. The movie is not out yet, and it is unlikely that I will watch it before it comes out on DVD, but I did read the book to see what all the hype was about. I d not know how they will adapt this book to the movie, such adaptations are always a chancy business and I am rarely satisfied with the result, but if the movie is at all faithful to the plot of the book, it will be well worth watching.

The_Martian_2014

The Martian is not, as the title would suggest, a science fiction novel about a person from the planet Mars. Instead it is the story of astronaut Mark Watney who is one of a crew of six astronauts on a mission to explore Mars. A dust storm causes NASA to abort the mission after only six days on the surface of Mars and Watney is seemingly killed while the crew is trying to get to the Mars Ascent Vehicle which is designed to return the crew to their orbiting space craft Hermes which will take them home to Earth. However, Watney is not dead but has been left behind, all alone on Mars with no way to return to Earth or even to communicate with NASA. The rest of the novel is concerned with Mark Watney’s efforts to stay alive on Mars until he can be rescued.

 

In many ways, The Martian is a hearkening back to the great, old days of science fiction, to a more optimistic time when science fiction was about man’s exploration of the universe and nothing seemed impossible with the application of scientific knowledge and reason, rather than the pessimistic post-apocalyptic dystopias and social justice warrior crap that one sees too much of in the genre these days. The plot is well paced and exciting. Although I knew that Watney will make it off of Mars, this isn’t the sort of story that has him die at the last minute, the question of just how he will manage the next crisis kept me, almost literally, at the edge of my seat and made the book almost impossible to put down. Mark Watney himself is an engaging character, something of a twenty-first century Robinson Crusoe, clever and resourceful enough to find ways to survive. Just as Crusoe was able to salvage his wrecked ship to enable himself to survive on his island, Watney is capable of making use of the equipment left behind on Mars. Much of the story is told by way of the audio log he keeps and his often humorous commentary on the conditions and problems he faces helps to make what might be tedious exposition enjoyable to read. There is no Man Friday on Mars for Watney, but scavenging the Pathfinder lander allows him to regain contact with Earth which surely must be just as momentous as Crusoe’s finding a footprint in the sand and realizing that he no longer has to face his troubles alone.

The story is also told from the point of view of Mark Watney’s crew-mates and the engineers and administrators at NASA who are desperately trying to find a way to bring Watney home, or at least send him supplies to last until the next mission to Mars. They are shown to be competent, loyal and determined and in that respect The Martian reminded me of the movie Apollo 13. The science in the Martian is rock solid and this is one of the hardest, on the scale between hard to soft, science fiction books I have ever read. Andy Weir is the son of a scientist and a student of science himself. All of the technology in the book is based on real life technology we have right now and the mission to Mars is based on real plans that NASA might adopt to send astronauts to Mars. Weir’s portrayal of Martian conditions is based on the very latest information from probes. If a man ever did get stranded on Mars, this is a realistic story of how he might survive.

I can highly recommend The Martian to any reader whether science fiction fan or not. There is just one problem. The Martian actually makes the prospect of living on Mars seem desirable. Ever since I finished it, I have had the most intense desire to hop on a spaceship and go to Mars myself. Where do I sign up?

The red hills of Mars

The red hills of Mars

 

Wheels within Wheels

June 1, 2015

In the previous post, I left off the history of astronomy with Claudius Ptolemy, the last and greatest of the astronomers of ancient times. It was Ptolemy who brought the science of astronomy to its apex in classical times. In his treatise, the Almagest, as the Arabs came to call it, Ptolemy worked out the geocentric model with the complex system of epicycles that the ancients believed described the universe, along with a catalog of stars and constellations and tables of information on the motions of the planets and eclipses of the Sun and Moon. So well did Ptolemy do his work that the Almagest was the accepted text on astronomy for over twelve hundred years.

The science of astronomy did not stand still after the time of Ptolemy. The Western Europeans were a little distracted by the fall of the Roman Empire in the West and contributed little to the progress of learning for some centuries. Fortunately the ancient learning was preserved in the Greek East and when the Arabs conquered much of the Middle East in the century after the death of Mohammed, they were able to learn much from the peoples they ruled and soon began to make contributions of their own in science and philosophy. The Arabs translated many Greek texts into Arabic which Western scholars discovered and translated into Latin. The contributions made by the Arabs can be seen by the fact that Ptolemy’s standard text is known by its Arabic title and that many stars still retain names derived from  Arabic

Throughout the Early Middle Ages, the Muslims translated Greek texts into Arabic and so helped to preserve them until Western scholars could translate them into Latin once things had settled down in the West. The importance of the Arabic contribution can be seen by the fact that Ptolemy’s book is known by its Arabic title, not to mention that many stars are known by names derived from Arabic; Betelgeuse, Algol, Aldebaran, Deneb, Vega, and many others.

Over time, the Arabs, and later the Europeans, developed better instruments for observing the positions of the stars and planets in the sky and to predict the motions of the planets. As their techniques improved, astronomers were able to revise and update the information on planetary motions collected by Ptolemy, and they also found that more epicycles were needed to explain and predict planetary motions. The Ptolemaic model began to seem increasingly over complicated. The last major revision of the tables of planetary motions was commissioned by King Alfonso X of Castile in the thirteenth century. Alfonso, called “the Wise” was known as a patron of many branches of learning and was himself conversant in the science of astronomy. He is supposed to have remarked that if God had consulted him during the creation, he might have suggested a simpler system than the complicated bicycles of Ptolemy. The king almost certainly did not say this, but the sentiment was shared by many who began to believe the universe shouldn’t be so complicated.

Among these was a Polish priest who lived some two hundred years after Alfonso. This priest was named Mikolaj Kopernik, better known by the Latinized version of his name, Nicolaus Copernicus. Copernicus was a true renaissance man who was learned in such diverse fields as mathematics, canon law, medicine, economics, classical languages, diplomacy, politics, and astronomy. It is in that last subject that he is remembered today. Copernicus came to realize that understanding the motions of the planets would be much easier if he simply assumed that the planets revolved around the Sun rather than the Earth.

Copernicus

Copernicus

The retrograde motions of the planets could simply be explained by their overtaking the Earth as they orbit the Sun. Copernicus seems to have developed his heliocentric theory by 1514 and spent much of the rest of his life working on his book “De revolutionibus orbium coelestium” or “On the Revolutions of the Heavenly Spheres”. Although Copernicus showed the manuscript to his friends and interested scholars, he was reluctant to actually publish his masterpiece for fear of the public ridicule such a radical theory might bring him. It was only after his friends assured him that the book would be favorably received and he was dying that Copernicus agreed to publish De revolutionibus in 1543.

De revolutionibus was favorably received by the few people who actually read it. The fact was that Copernicus’s book was so abstruse and technical that only astronomers and mathematicians could really appreciate and understand it.

It was in Latin and the script was hard to read too.

It was in Latin and the script was hard to read too.

Copernicus’s heliocentric model was not generally accepted for some time. The fact that the assumption that the Sun was at the center of the Solar System made calculating the motions of the planets less complicated did not necessarily made that assumption true and there was good reason not to believe the Earth moved. In fact, the Copernican model did not make the calculations that much less complicated. Like Aristotle and Ptolemy, Copernicus believed that the planets moved in perfect circles and his theory still required some epicycles to agree with observations. It was not until 1610 when Johannes Kepler proposed his first law of planetary motion, that the planets orbit the Sun not in circles that the need for epicycles was finally done away with. The heliocentric model then clearly provided a simpler means of understanding the motions of the planets and so was quickly adopted by most astronomers even though there was not yet clear proof that it was actually true.

Which brings us back to Galileo and the Church. In 1632, the year Galileo was tried by the Inquisition, the heliocentric model was rapidly gaining acceptance, yet from a strictly scientific viewpoint, the Church was quite correct in regarding the model with skepticism, even if it was not correct from any viewpoint to put Galileo on trial, although as I said Galileo himself was mostly to blame for his troubles. And, here I have to ask again, why was the heliocentric theory adopted a century before it could be proven beyond a reasonable doubt?

Scientists like to portray themselves cool, logical, unbiased observers interested only in the facts, that is the results of their observations and experiments. Any hypothesis, no matter how attractive, must be put aside if the observations do not agree with it. In fact, scientists are subject to the same sorts of biases as everyone else and a candid view of the history of science will show many instances when scientists have clung to a hypothesis even when the facts seem to show otherwise. This is not always a bad thing. I would even go further and state that this is often a good thing. Sometimes intuition serves as a better guide to discovering the truth than logic and sometimes finding the truth requires ignoring the facts that seem to point in a certain direction while pursuing an underlying truth.

One of the biases that has proven to be most useful in understanding the nature of the universe we live in is the idea that the universe is, as bottom, a simple place that we can understand. If things get to be overly complicated, it is usually taken as a sign we are moving in the wrong direction and should seek a simpler explanation. This is no scientific reason for believing this is the case, yet this bias has proven to be useful over and over again. Ptolemy’s epicycles became more and more complicated, so astronomers switched to the simpler heliocentric system, and were proven right. Physicists and chemists in the nineteenth century were dismayed to discover more and more chemical elements with no clear pattern, until they discovered that all these elements could be explained by the three particles, electrons, neutrons, and protons found in the atoms of every element. Physicist were then confused by the many sub atomic particles they kept discovered, until they learned that these particles were composed of a handful of still smaller particles called quarks. This is really the essence of science, to find simple patterns to explain complex phenomena and this process requires intuition and imagination as much as it requires logical thinking and careful observation. So, Galileo was right, even when he was wrong.

Galileo Was Wrong

May 31, 2015

That is the idea behind an odd website that I found which promotes the theory of geocentrism or the idea that the Earth is the center of the Solar System and that the Sun revolves around the Earth. Geocentrism was, of course, the idea held by every astronomer and scientist up until 1543 when Nicolaus Copernicus proposed his heliocentric, or Sun centered, model of the Solar System. For about a century there was a fierce debate among scientists and philosophers over the true structure of the universe. Heliocentrism won out, of course, and no educated person of the twenty-first believes that the Earth is at the center of the universe. Because of this, those who historically had supported Copernicus’s model, such as Galileo are held to be on the right side of science and history, while those who clung to the older geocentrism, such as many officials of the Roman Catholic Church, seem to have been backwards and on the wrong side. This website contends that in the controversy between Galileo and the Catholic Church, the Church was, in fact, in the right and Galileo was in the wrong, hence the title. The strange thing is that the website is actually correct, in a funny sort of way. Galileo really was in the wrong and the Church was right to be skeptical of Copernicus’s theories.

The controversy between Galileo and the Church has often been depicted as part of the never ending battle between the light of science and religious ignorance. It is generally accepted by historians today that Galileo’s troubles had far less to do with an alleged anti-science position taken by the Catholic Church and more to do with contemporary Italian politics and Galileo’s own irascible personality. What is generally less well known is that the Church had good scientific reasons to oppose Galileo. Neither Copernicus or Galileo had any way to prove that the Earth moves around the Sun. With his telescope Galileo did discover the four largest moons of Jupiter and the fact that Venus shows phases, which indicates that it orbits the sun. These discoveries were certainly  suggestive in that they showed that not everything in the sky directly orbited the Earth, but it was possible that while Venus and the Galilean satellites orbited the Sun and Jupiter, the Sun and Jupiter revolved around the motionless Earth. In fact, there wouldn’t be any conclusive proof that the Earth moves until eighty years after Galileo’s death when the astronomer James Bradley discovered the phenomenon of the aberration of light caused by the Earth’s motion through space.  By this time, there was hardly any doubt about the Earth orbiting the Sun.

Why were astronomers so quick to discard the millenia-old and common sense idea that the Earth rests motionless at the center of the universe without any direct proof? The answer is that a heliocentric Solar System better accounted for the motion of the planets. In order to understand this, we will have to go back to the origins of the science of astronomy.

No one knows where or when people began to really observe the night sky and take note of the motions of the heavenly bodies. It must have seemed obvious that the Earth was a flat surface with the sky a dome enclosing it. The Sun, Moon and stars rose into the sky moved from East to West across the sky and then set beneath the Earth. At some point, these early observers noticed that not all of the objects in the sky moved along with the background of stars. These objects seemed to wander about the sky, so the Greeks referred to them as planetes, or wanderers. There were seven of these “planets”. the Sun and Moon, and five star like objects that were named Mercury, Venus, Mars, Jupiter, and Saturn. It may seem strange to refer to the Sun and Moon as planets but they like the other planets, moved across the sky against the background of the fixed stars.

The Greeks and the Romans knew that the Earth is round and the Greek philosophers such as Plato and Aristotle held that the circle was the perfect shape. Because they believed that the Heavens were perfect and unchanging, as opposed to our corrupt and changing Earth, they believed that the seven planets orbited the Earth in perfect circles. This was the model proposed by the ancient Greek astronomers, especially the last and greatest of the Hellenistic astronomers, Claudius Ptolemy, who lived in the second century AD. For this reason the geocentric model is often called the Ptolemaic model.

There was a major problem with the model proposed by the ancient Greeks, the planets do not move in perfect circles across the sky from West to East against the background of the stars. The planets moved in different paths across the sky and at different speeds. Sometimes they seemed to move backwards in what was called retrograde motion.

This image was created as part of the Philip G...

The retrograde motion of Mars(Photo credit: Wikipedia)

As Earth passes Mars, the latter planet will t...

As Earth passes Mars, the latter planet will temporarily appear to reverse its motion across the sky. (Photo credit: Wikipedia)

 

This apparent retrograde motion is is observed because the planets revolve at varying distances from the Sun and so orbit at varying velocities around the Sun. The Earth being closer to the Sun than Mars travels faster than Mars and so occasionally overtakes the other planet. Venus and Mercury travel faster than Earth and overtake us occasionally. You might be able to get an idea of how this works by considering a group of cars travelling on an Interstate. If I am driving at 60 miles per hour and pass a car that is going at 55 miles per hour, that other car will seem to be going backwards even though we are both going in the same direction. As a car travelling 65 miles per hour passes me, I will seem to be moving backwards to them.

 

In order to account for these dependencies between Aristotelian theory and astronomical observations, Greek astronomers hypothesized that while the planets move in perfect circles, they also moved in smaller circles within the circles. Thus, the heavens were full of wheels within wheels. It was Claudius Ptolemy who developed this system to the form that was used in Medieval astronomy.

epicycle-epicycle

It is easy to disparage Ptolemy for developing such a cumbersome system of concentric circles, but remember he did not have the telescope or many of the instruments invented to observe the motions of the planets that came into use in later years. He certainly cannot be blamed for assuming that the Earth is motionless. After, we cannot feel the Earth move and if we had to go by our own personal observations, we could only conclude the same. In fact, Ptolemy’s system was able to predict the motions of the planets with a high degree of accuracy and this was what the ancient and medieval astronomers were most concerned with.

There is much more to say about how later generations of Islamic and European astronomers refined and improved Ptolemy’s model as better astronomical instruments were invented and how Ptolemy came to be at last dethroned, but I am afraid that will have to wait for another post.

 

The Rolling Stones

May 5, 2015

The Rolling Stones Robert A Heinlein‘s story of the great American road trip updated for the space age. Like Heinlein’s other juvenile science fiction novels written in the 1950’s, The Rolling Stones is great fun to read and teaches the lessons in self-reliance, courage and rational thinking found in all of Heinlein’s books for young adults.

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The plot of the Rolling Stones is simple enough. Castor and Pollux Stone, two fifteen year old twins who are Loonies, lunar colonists, want to buy a used space ship so they can begin a career in interplanetary trade. They ask their father, former mayor Roger Stone, for their inheritance in advance, but he outright refuses, insisting that they need to complete their education. The other members of the family, his wife Dr. Edith Stone, older daughter Meade, younger son Lowell, or Buster, and Roger’s mother Hazel Meade Stone, a founding mother of the Lunar Free State, convince him to buy a larger space ship for the use of the whole family. Soon, the Stones are on a trip to Mars and then the Asteroid Belt. They encounter some problems, but are able to resolve them with careful thinking and ingenuity. At the end, the Stones are on their way to Saturn to see the rings.

This book was published in 1952, before any human being had gone to space and even before Sputnik, yet Heinlein was amazingly accurate in his descriptions of how space travel would actually work. Heinlein was an engineer and he clearly put a lot of thought and research into writing this book, perhaps more thought than many might bother with for a story aimed at young adults. The Stones do not just push a few buttons and head for Mars. They must  go through a take off procedure much like that of real space craft. They must carefully calculate the proper course and account for the orbits of the planets in order to get to their destination.

With all of that being said, it is interesting to note where Heinlein and other science fiction writers of his time got things wrong. In general it has proven far more expensive and difficult to establish a human presence beyond low earth orbit than anyone anticipated. Space is a more hostile environment than thought and the extended period of weightlessness experienced by the Stones on their trip would probably leave them crippled by the time they reached Mars, unless they managed to provide some sort of artificial gravity, perhaps by rotating their ship. The depictions of the planets in Heinlein’s juveniles is far out of date. Neither Mars nor Venus is habitable without extensive terraforming and there are no natives, alas. What is most remarkable for an engineer like Heinlein is the inability to predict the electronic and computer revolutions. The computers in Heinlein’s juveniles are still huge, room sized contraptions and the characters use slide rules to perform calculations. I imagine that when the time comes when families are able to take trips to other planets, there will be an app to calculate trajectories.

I said that The Rolling Stones was the story of a road trip, but it is also the story of the ever expanding frontier. Heinlein’s political and social views were often described as libertarian, but perhaps a more accurate label would be frontier. On the frontier, whether in the Old West or in space, people cannot wait for a distant government to solve their problems or take care of their needs. By the time the government even learns of their problems, they may be dead. The people on the frontier must learn to take care of themselves and once they have become used to taking care of themselves, it is hard for them to accept the idea that their betters in a distant capital are more capable of solving problems that they are. The frontier creates a political climate that emphasizes equality over hierarchy and individual freedom over regimentation. It may be that many of the problems America is currently facing, not least an ever more intrusive and lawless government and a ever shrinking personal sphere of individual freedoms, is precisely because we no longer have a frontier. If this is the case than the sooner we get up into space, the better.

Political musings aside, The Rolling Stones is an enjoyable story that can appeal to youngsters of any age.

The Nativity According to Matthew

December 20, 2014
The Adoration of the Magi (circa 1305) by Giot...

The Adoration of the Magi

Matthew begins his Gospel with the genealogy of Jesus. I’ll skip the genealogy and go straight to his account of Jesus’s birth.

18 This is how the birth of Jesus the Messiah came about: His mother Mary was pledged to be married to Joseph, but before they came together, she was found to be pregnant through the Holy Spirit. 19 Because Joseph her husband was faithful to the law, and yet did not want to expose her to public disgrace, he had in mind to divorce her quietly.

20 But after he had considered this, an angel of the Lord appeared to him in a dream and said, “Joseph son of David, do not be afraid to take Mary home as your wife, because what is conceived in her is from the Holy Spirit. 21 She will give birth to a son, and you are to give him the name Jesus, because he will save his people from their sins.”

22 All this took place to fulfill what the Lord had said through the prophet: 23 “The virgin will conceive and give birth to a son, and they will call him Immanuel” (which means “God with us”).

24 When Joseph woke up, he did what the angel of the Lord had commanded him and took Mary home as his wife. 25 But he did not consummate their marriage until she gave birth to a son. And he gave him the name Jesus.

After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, “Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.”

When King Herod heard this he was disturbed, and all Jerusalem with him. When he had called together all the people’s chief priests and teachers of the law, he asked them where the Messiah was to be born. “In Bethlehem in Judea,” they replied, “for this is what the prophet has written:

“‘But you, Bethlehem, in the land of Judah,
are by no means least among the rulers of Judah;
for out of you will come a ruler
who will shepherd my people Israel.’

Then Herod called the Magi secretly and found out from them the exact time the star had appeared. He sent them to Bethlehem and said, “Go and search carefully for the child. As soon as you find him, report to me, so that I too may go and worship him.”

After they had heard the king, they went on their way, and the star they had seen when it rose went ahead of them until it stopped over the place where the child was. 10 When they saw the star, they were overjoyed. 11 On coming to the house, they saw the child with his mother Mary, and they bowed down and worshiped him. Then they opened their treasures and presented him with gifts of gold, frankincense and myrrh. 12 And having been warned in a dream not to go back to Herod, they returned to their country by another route.

13 When they had gone, an angel of the Lord appeared to Joseph in a dream. “Get up,” he said, “take the child and his mother and escape to Egypt. Stay there until I tell you, for Herod is going to search for the child to kill him.”

14 So he got up, took the child and his mother during the night and left for Egypt, 15 where he stayed until the death of Herod. And so was fulfilled what the Lord had said through the prophet: “Out of Egypt I called my son.”

16 When Herod realized that he had been outwitted by the Magi, he was furious, and he gave orders to kill all the boys in Bethlehem and its vicinity who were two years old and under, in accordance with the time he had learned from the Magi. 17 Then what was said through the prophet Jeremiah was fulfilled:

18 “A voice is heard in Ramah,
weeping and great mourning,
Rachel weeping for her children
and refusing to be comforted,
because they are no more.”

19 After Herod died, an angel of the Lord appeared in a dream to Joseph in Egypt 20 and said, “Get up, take the child and his mother and go to the land of Israel, for those who were trying to take the child’s life are dead.” (Matthew 1:18-2:20)

Most people think that the slaughter of the baby boys in Bethlehem involved the murder of hundreds or thousands of innocents. Remember, though, that Bethlehem was a small village in this time with a likely population of a few hundred. It is doubtful that more than half a dozen children were killed, not enough to make it into any other sources we have for Herod’s rule. Herod was certainly ruthless enough to order such a massacre. He had no trouble killing members of his own family if he thought they threatened his rule. In fact, Herod being an Idumean (or Edomite) and not a Jew, was a foreigner and so was as despised by many Judeans as a Roman governor would have been. If he had heard that there was a potential rival to his throne, even a child, that the Jews might rally around, he would have wasted no time in disposing of that rival.

The word Magi usually refers to Zoroastrian priests. In Greco-Roman usage the term Magi had connotations of magicians or sorcerers, exotic figures from distant lands. It is not clear just who the Magi actually were. They may indeed have been Zoroastrians. The references to the Star of Bethlehem suggest that they may have been astrologers. The Babylonians had a reputation for being skilled in astrology and magic so the Magi may have come from Mesopotamia. They may also have been Jewish since they were seeking for a king of the Jews. The fact that they were unfamiliar with the prophets may prove that they were Gentiles. The number of the Magi is not given in the Gospel. The reason that three are usually pictured  is that there were three gifts; gold, frankincense,and myrrh.

It is also not clear just what the Star of Bethlehem actually was. There have been several theories presented, but none of them are entirely satisfactory. The star might have been a supernova, perhaps in a nearby galaxy. There is no way to know for certain since any supernova remnant so far away would be difficult, perhaps impossible, to detect. It might also have been a comet. This is rather unlikely. Although a comet would behave much as the star is said to behave, hanging in the sky over a certain location for several nights, comets were universally perceived as being harbingers of disaster in ancient, and not so ancient, times. The most likely explanation is a conjunction of the planets Jupiter and Saturn. The astronomer Keppler discovered that there was indeed such a conjunction in the year 7 BC. The following year there was another conjunction of Mars, Jupiter, and Saturn. This might have been very impressive to the Magi. It may also be that the Star was a supernatural phenomenon and one that cannot be studied today. Whatever the truth of the matter is, I hope everyone has a wonderful Christmas.


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