Science placards around the world

This placard from Boston is my absolute favourite from the biggest science event in history, the global March for Science on 22nd April.   And here are the runners-up:-

In no. 2 place, Think while it's still legal.  A similar thought prompted a Swedish placard in Stockholm: Våga Fråga! (the å's are pronounced like English "or"). It means "Dare to ask", nicely encapsulating the scientific enterprise - enquire, then follow the data wherever it leads.

I must include I'm not a zoologist ... perhaps I should have placed it higher up my list, but here it comes at no. 4:-

And this photo contains a few more worth a glance.  You've got to smile at When do we want it, after peer review, and Paid scientist, I protest for free.  Science not silence was a slogan used in many protests across the globe.  We can call these 4(a), (b) and (c). Next,  Less Invasions More Equations deserves a place, here it is at no. 5:-

I'm with Her is a nice repurposing of a Hilary Clinton slogan. This one was from Paris:-

Not an alternative fact was mass produced, I've seen it in numerous photos, so while certainly rating a mention, I have to put it bottom of my list:-

All good humoured stuff. A pity then that we have to end on a sour note. Did Donald Trump really need to turn up in New York and spoil the day by playing golf with the Earth? So very sad.

Jupiter over Death Valley

To Ballingeary near Cahir, Co Tipperary, on Wednesday to give a talk on a few curious facts about the universe to an ICA meeting (Irish Countrywomen’s Association). An appreciative audience. I showed them some arresting graphics of the relative sizes of the Earth and the other planets - but nothing I produced could match an image which I have just come across showing what Jupiter would look like in our sky if at the same distance as the Moon.

 

It's as if seen from Death Valley, California, by space artist Ron Miller. At the Moon’s distance (c. 240,000 miles, or 386,000 km) Jupiter appears about 1,600 times larger than the Moon, shown for comparison in the next image:

Jupiter is our solar system’s largest planet, two and half times as massive as all the other planets together.

Miller's images were published in The Atlantic, along with Saturn and the other planets, each hovering over Death Valley. 

And here’s a link to Ron Miller’s other work.

Changing day length in Luleå

Spring soon.  Evenings stretching out apace, wasn’t really dark tonight till seven. Though here in County Cork we're in the wrong time zone. This means that sun-wise, it would be truer to say it got dark about a quarter past six. 

I now want to say something about the stretching of the days in Luleå during my recent stay there. In Cork the shortest day is 7 hours 46 minutes, and the longest 16 hours 43 minutes: hence between midwinter and midsummer the sun has almost 9 hours to chase. In Luleå, the difference is nearly 20 hours; consequently the stretching of the days is more rapid, and I was hoping to be able to observe this effect over the course of the seven days I was there. But I was disappointed, and if you bear with me I shall explore the reasons for this.

My visit was from 18th to 25th February, during which time the days lengthened by 49 minutes. I know this from tables available at timeanddate.com.

Over those seven days, sunrise moved 26 minutes earlier, and sunset 24 minutes later. That adds up to a 49 minute increase (due to rounding). This is almost double the difference in Cork, where during the same week sunrise got 14 minutes earlier and sunset 12 minutes later. You can see all this in the table next to the map. 

Location map for Luleå, and sunrise/sunset table for Luleå and Cork. Minutes are rounded.

To put it another way, when I arrived in Luleå, the day was 1 hour 20 minutes shorter than in Cork, and when I left, it was 1 hour 6 minutes shorter.  Today it was a mere 24 minutes shorter. Come the 21st March (just to remind you) the days in Cork and Luleå will be the same length, namely 12 hours, indeed the same all over the globe. [1]

I said I was disappointed. I actually noticed no change while in Luleå, no stretching of the mornings or evenings. This was partly because for several days skies were overcast.  But only partly. On reflection I realise that two factors work against each other.  The further from the equator, the shallower the sun’s trajectory in the sky. This makes sunrise and sunset more gradual, extending the period of twilight; and it means that during the northern spring, even though the daily increment in sunlight becomes greater as you travel north, the stretching of the days becomes harder to mark.

I cast my mind back to Trinidad where I spent a year in 1968. In the tropics the sun never rises and sets far from 6 o’clock.  A typical sunset conversation would go: “You noticed the sun’s setting much later now?” ... “Yes, tonight it was 7 minutes past. A few weeks ago it was 4 minutes past.”

Here is a table comparing Luleå, Cork and Trinidad for the week in question. It shows that where the daily increment in daylight is greater, twilight is also longer.  [2]

The paradoxical consequence is that in Trinidad, even a tiny difference in day length can be more noticeable over a short period of time than a very significant increase over the same period in Luleå.
 
I have a set of three diagrammes which may help to illustrate this. They apply to the winter solstice, 21st December, and show sunrise, sunset and the sun’s altitude at midday, comparing the cases of Luleå (midday sun altitude 1°), Cork (15°) and Trinidad (56°).

Daylength table anomaly

I'll now mention an anomaly I can't get to grips with.  This arises from studying the daylength tables in preparation for writing this blog post.

In the spring, as the sun sets further and further north each day, the daily increment in day length ought to peak around the equinox (21st March), and after that gradually lessen. From equinox to midsummer, though the days continue to get longer, the increment from one day to the next becomes less and less marked. When midsummer arrives, the day to day increase is zero; the sun no longer sets further north but stands still and then starts to set further south; so that after 21st June (the solstice) the day length begins to decrease again.

Why is it called the solstice? A digression

Solstice is a bad word. It means sun stands still in Latin - but who knows or cares for Latin? In Swedish it's solstånd (sun-stand) and in German Sonnenwende (sun-turn). Much better.

Thus in Cork, the daily increment in day length peaks in mid March at 4 minutes 1 second, and begins to decline after the 27th.  During April the daily increment slows, so that at the end of that month the daily increment is down at 3 minutes 35 seconds.  The decline in the daily increment continues during May, down to under 2 minutes. By 12th June it's down to 54 seconds.  All that is good and just as it ought to be.

But the day length table for Luleå tells a strange tale.

Throughout February the daily difference is just over 7 minutes - oddly 4 seconds longer at the beginning of February that at the end.  For most of March - when you would expect the daily day length increment to be at its maximum – it dips just under 7 minutes. Then, throughout April, when the daily increment ought to be slowing,  it again tops 7 minutes.  The daily difference is 7 minutes 22 seconds on 30th April and continues to rise, peaking, extraordinarily, in the second half of May, at 7 minutes 40 seconds.  And it doesn't dip under 7 minutes till 9th June. Weird!  I must find out why this is, something to do with the Earth wobbling on its axis or being a funny shape I suppose.

Notes:

[1]  In most of the tables I've looked at, it's actually 18th March when the day length hits 12 hours.  The leap day on 29th February distorts the picture of course, but even adjusting for that, you get the 19th March. I don't know why this is.  And what about the two Poles I ask myself?  I haven't found any table for them.  My understanding is that they have only one day and one night, sunrise at the North Pole on 21st March and sunset on 21st September. South Pole vice versa. So is “12 hours all over the globe” correct or not?

[2]  About twilight. I've used civil twilight: the limit of which is defined by the sun's centre being 6° below the horizon. Solar illumination is insufficient, even under clear weather conditions, for terrestrial objects to be clearly distinguished, and artificial light is needed to carry on most outdoor activities. There are actually three definitions of twilight, the other two being nautical twilight and astronomical twilight, but civil twilight is most relevant for my purposes today.

A Dyson sphere, my eye!

The central dot in this image represents a star surrounded by a Dyson ring of solar power collectors, 100 million miles out from a star. Many rings would make a Dyson sphere. Loopy!!
Image via Wikipedia.

When it comes to extraterrestrial life and space colonisation by humans my intuitive response is, this is fantasy stuff, and not worth a second glance.

I'm thinking in particular of the notion that star KIC 8462852 may sport a Dyson sphere. And what, pray, is one of those?  Oh yes, it's a hypothesized artificial structure surrounding a star. A structure the size, say, of Earth’s orbit around the sun, consisting of a shell of solar collectors. The idea being that with this model, all (or at least a significant amount) of a star’s energy would hit a receiving surface where it can be used. The physicist Freeman Dyson speculated that such structures would be necessary for the long-term survival of a technological civilization due to its escalating energy needs.

Madness. But madness or not serious scientists looking at the data from the recently discovered KIC 8462852 think it's behaving so strangely, that this Dyson sphere conjecture is worth exploring.  Jason Wright, an astronomer from Penn State University, is quoted in The Guardian  “Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilization to build.”

Even as “the very last hypothesis” this is surely loopy!  … and yet ... as a mere bystander, who am I to say, no this cannot be?

When I need an image for a space colony I invariably seem to revert to this representation from the Mars One website

Space colonies aren't quite so far out and yet I struggle to take them seriously too. Dr Cameron Smith is someone who’s caught my eye. An archaeologist at Portland State University, he has arresting views on how space-born descendants of explorers would evolve culturally and genetically.  His theme is the biological and cultural dimensions of human space colonisation. 

This will be a process of adaptive evolution, and he thinks evolutionary studies can help plan for its success. He proposes to found a new science that he calls exo-anthropology. He envisages different models of space colonization:-

•    Terrestrially-tethered colonies
•    Independent colonies on other solar system bodies
•    Independent colonies aboard 'closed-system' spacecraft

I recommend listening to an hour-long audio file of a teleconference held last year with scientists from NASA and the University of Texas.  There are slides to accompany his talk, and you can find them on this page. (Look for a pptx file.)

Space colonisation will be a natural continuation of 4 million years of adaptation, he believes.  Against our nature?  No … ever since the human dispersal out of Africa, we’ve always found new places to live. Why would that stop with the atmosphere, he asks?  Plenty of technical reasons maybe, but no reason against space colonisation either philosophically, or evolutionarily. Humans have always perceived new environments and then gone on to colonise them.

All except Antarctica that is. There are some scientific stations,  but where are the colonies, where are the children, huh?  There's the flaw is his scheme surely.  Mars is many times less hospitable than Antarctica.

He says we require a science of extraterrestrial adaptation. It will be an evolutionary transition on a par with our ancestors coming down from the trees.  Humanity has long considered colonising space, and at present we're at the exploration stage, thinking of individuals and how they could survive on Mars. But  as an anthropologist he thinks of groups. Biocultural evolution, co-evolution of genes and culture, that’s what anthropologists study.  Up to now the anthropologists have looked at the present and the past. Cameron Smith wants them to turn their attention to the future.

Dr Cameron Smith, exo-anthropologist

He cites the example of high-altitude societies in the Andes and Tibet. Here genetic mutations allow more efficient blood oxygenation. There's cultural adaptation too, for example in the Andes mothers move down to lower altitude before giving birth. Maybe on Mars there will be a need to give birth in 1g gravity, so, by analogy with practice in the Andes, mothers perhaps will ascend to an orbital station with artificial gravity.

We can expect both beneficial and deleterious mutations to arise off-Earth he says.  Evolution will be driven by selection pressures arising from the different  gas composition, lower atmospheric pressure, and lesser gravity.  All these factors will differ from the Earth conditions that have shaped human embryo development for millions of years.  On Mars we'll see the return of natural selection, big time.   There will be an increase in infant mortality, he sees no way round this.

The Q&A session following his talk is worth listening to as well. A Mars colony would be physically fragile at first, and highly susceptible to sabotage by any of its members who went awry.  A whole new approach to mental illness will be called for.

If a one-hour audio file is too much to digest, Dr Smith also gave a 10-minute talk for SETI Big Picture Science, called “And to space we return”.

Monkeying with the clocks

Here in Cork we get half an hour extra daylight in the evening, though our mornings are dark. That’s because we use the same time zone as Britain whilst lying half an hour west of Greenwich. So the gloom and darkness complaint that arises at this time of year affects us less acutely. Here's a sample, in The Observer’s editorial last Sunday:-

For the next five months, the nation can again anticipate evenings marked by their gloom and darkness, thanks to Greenwich Mean Time, which was reintroduced early this morning.

Few welcome the abandonment of British Summer Time, one of the least appetising events of the calendar, and opinion polls in England and Wales make it clear there is a healthy support for the halting the practice of putting clocks back in autumn so that we have earlier sunrises and sunsets and darker evenings.

The editorial goes on to suggest that retaining British Summer Time in the winter, with the addition of an extra hour to clocks in March (Double Summer Time), would save money and lives. Lives on the roads because the evening rush hour wouldn't be so dark, and money because there would be less need for electric light in the early evening.  This kind of scheme is always referred to as daylight saving.

Greenwich Observatory. Where midday really is midday.

And it's said every year at this time when the clocks go back.  But the point I'm coming to is this: how have we got ourselves into this back to front way of running a society?  When The Observer talks of “gloom and darkness, thanks to Greenwich Mean Time”, they make Greenwich Mean Time sound like a perverse invention designed as a kind of torment.   But hey, all it means is that the Sun is at its highest in the sky at midday (in Greenwich that is). Which is exactly as it should be.  (In York too; in Bradford the Sun doesn't reach the zenith till almost 7 minutes past midday; here in Mitchelstown Co Cork, 32 minutes past.)

If we feel so strongly about dark evenings, the answer is clear. Bed at 8. Up at 4. Standard working day from 7 am to 3 pm, which even in midwinter finishes in full daylight. Outlandish? Of course. But only because sometime between the 16th and 18th centuries our forebears did something called nocturnalisation.  Staying up half the night and sleeping till half way through the morning. The daylight saving that The Observer is calling for amounts to this:  to monkey with the clocks so as to wind this nocturnalisation back, nearer to the way things once used to be. 

Jiggery pokery

I'm not really against monkeying with the clocks. I just want to get it off my chest that the whole thing’s mad.  We’ve nocturnalised our society and now we want to unnocturnalise it. Just why nocturnalisation occurred is a puzzle I wrestle with from time to time.  I touched on the history of it a couple of years ago in a piece called How we colonised the night.

As a postscript I should add that the foregoing is entirely a parochial mid-latitude issue. In Scotland monkeying with the clocks probably wouldn't work. And in Luleå no amount of jiggery pokery is going to stretch out the three or four hours of watery light that’s the midwinter ration. In the tropics on the other hand, the Sun never rises and sets far from 6 o’clock.  I remember when I was in Trinidad in my youth observing that the earliest sunset was 5:45, and the latest sunset was 6:15. Here's a flavour of the conversation you would have sitting on the porch sipping rum and coke and the crickets chirping. “You noticed the sun’s setting much later now?” ... “Yes, tonight it was 7 minutes past. Two weeks ago it was 4 minutes past.”

Finally, here's a useful short history of daylight saving measures. Double Summer Time was first used in Germany in the First World War, quickly followed by Britain and many other countries.

Of fundamental particles and logs

This is a plug for the Guardian’s Science Weekly podcast. In fact for Guardian podcasts overall. I reckon that were the Guardian a radio station it would be up there with BBC Radio 4 as one of the world’s best. The episode of Monday 28 July featured British physicist Professor Jon Butterworth discussing his work at the Large Hadron Collider.  Just a lot of quite ordinary people getting on with their jobs in a building with shabby corridors, he says, yet they're unlocking the laws of nature and the secrets of the universe.

The whole episode lasts 44 minutes and the Jon Butterworth interview takes up the second half, starting at minute 22:40.  If you have time for just a three minute snippet, try from minute 36:30 to 39:36. Listen to the professor’s thoughts on finding that the Higgs particle is really there, and seeing confirmation of the Z-boson.  By the way don't worry, there's no need to understand exactly what the Higgs or the Z are, other than to know that they are fundamental particles that it takes expensive equipment to detect ... and upon their existence or non-existence rests our whole conception of the laws of nature.

Hear Jon Butterworth say “The fact that we understand nature so well, that when we turn on the Large Hadron Colider for the first time, we see the Z-boson, and it's where it should be, still impresses me, I still get goosebumps even talking about it now.” 

A bicycling engineer leans on a magnet in the 27km-long tunnel of the Large Hadron Collider
(Image: Cern/Maximilien Brice)

The thought he's expressing here isn't new, but when I hear a scientist say it gives them goosebumps, I get goosebumps myself.  I'm put in mind of another physics professor Frank Close, commenting on Dirac’s achievement in predicting the particle known as the positron (a positive electron). Dirac predicted the positron using maths alone, four years before the particle was actually discovered by experiment in 1932. 

“To me it’s remarkable, in a strange way I find it quite uncomfortable, that Dirac is writing things on paper, and the equations say: you can’t just have an electron, you must have a positive version as well.  And it turns out the equations know about nature; for then we go out and do an experiment, and we find that’s how it is.  It’s a very profound, in some way, a disturbing thing.” 

Prof Close was speaking on BBC Radio 4’s In Our Time in 2007. His words made such an impression that I included them in my personal collection of quotes from scientists talking about science.

To conclude about that episode of Science Weekly, Prof Butterworth was invited into the studio to talk about his new book Smashing Physics, his insider's account of the discovery of the Higgs boson. And the first half of the episode is a report from a symposium on the origins of life - did life begin on Earth or elsewhere, and how likely is it that we are alone. Science Weekly is presented by Guardian journalist Ian Sample. The episode of 4th August is another must-listen-to: “How AI could be the end of us”, in which Nick Bostrom believes if we're not careful, the creation of a super-intelligent computer could be our last invention. 

I listen to Science Weekly through my headphones as I go about my morning yard duties, and here's a picture to prove it:-

The log carrier by the way is a little thing of my own invention, loosely based on a traditional Swedish carrier made of birch bark.

Thankfully, infinity isn't all it's cracked up to be

According to the many worlds hypothesis, there exists an infinite number of universes, and consequently anything that can happen has happened an infinite number of times.  So there's another universe in which I went to bed early tonight and didn't get round to writing this stuff … and yet another in which I omitted the commas from the previous sentence … and so on. Actually an infinite number in which I did each of those things, but lets skip over that absurdity as the proposition is already absurd without it.  It makes my brain explode, and I refuse to accept that this is the way reality is.

So how do we account for this state of affairs? Until recently only two possibilities presented themselves. The first of which was that the many worlds hypothesis is false. There's either only one universe or a finite number of them.  Now, physicists may indeed have got it wrong, but it's hardly my place to say so, as they’ve done the equations and I haven't, nor could I.   So we must consider a second possibility.

Namely that there's something wrong with my intellect. Evolution has simply failed to equip me with a brain capable of grasping the truth about reality. Well, that may be the case; but I refuse to accept it; perhaps indeed, because I've been given the wrong sort of brain; but I refuse to accept it nonetheless.

Mary Midgley: infinity not all it's cracked up to be. And a book that’s just come down from the shelf.

Thankfully the other day in New Scientist I came across a way out of this impasse: a third possibility, that there's something wrong with the idea of infinity.

On the letters page the philosopher Mary Midgley wrote about the meaning of “an infinity” of universes, which she asserts to signify a mere absence of known bounds. Our ignorance of limits is just a negative, she claims. As such, it cannot spawn new facts. In particular it can't spawn the new fact that "everything that can happen will happen, infinitely many times". In this sentence,  infinite is used in a different sense, this time meaning a very large number. This sort of thing is not philosophy, she says, it's just muddled language.

So hurrah. The physicists may be right about an infinite number of universes, but we've misconstrued the consequences of this. There isn't another me that omits commas, and I can accept the possibility of many universes without my head exploding.

There's a book on my shelf about infinity which I've never read.  I see that from the inscription that I bought it at Oxfam in York in 2006. A Brief History of Infinity – the Quest to Think the Unthinkable, by Brian Clegg, 2003.  It's off my shelf now. Time to tackle it.

A short note on many worlds if you want it.

Quiz: what is the oldest manmade object in space?

Answer: this copper Lincoln penny, a 1909 US one-cent coin, launched into space on November 26, 2011, aboard the Curiosity Mars rover.

American geologists have long used Lincoln pennies as scale indicators in photographs. In homage to tradition, a 1909 one-cent coin is attached to Curiosity’s camera calibration target.

The second oldest human-made object in space, and until 2011 the oldest, is Vanguard 1, a satellite launched in 1958. It functioned until 1964, and is predicted to remain orbiting the Earth until the year 2198, when its orbit will have degraded so much that it falls in. It will presumably burn up in the atmosphere. But supposing any part reaches the ground and is picked up, by whom? Someone so technologically advanced we wouldn't recognise them, or by a cave dweller?

Came across this little nugget when researching space archaeology as part of a lecture I am due to give to an astronomy club next month.

Mars One is OK, I suppose

The pains of emigration are seared into the Irish soul, and this week I've listened on the radio to Dr Joseph Roche contemplating it in its most extreme form. He's a Trinity College Dublin astrophysicist who’s signed up for Mars One - a privately funded venture to send colonists to Mars in 2023 on a one-way only ticket. 

The first time I wrote about it, I queried whether a no-return crewed mission to Mars was acceptable.  Perhaps those who send these colonists will be colluding in their suicide?  This question of its acceptability was, I have to agree, a woolly one, as I forgot to ask acceptable to whom, and if not, who could stop it. 

Asked by the presenter if it's suicide, Joseph Roche recognises that due to radiation his life expectancy will be “drastically reduced”.  But since there can be very few people who understand the risks better than he does,  I suppose I have to abandon my pretensions to opine on the rightness of the thing. 

You can hear his two interviews here, on RTÉ radio last Thursday and Sunday. They make extraordinary listening. 

Morning Ireland, Thurs 9 January search for “The Irishman who hopes to go to Mars” (5 minutes)

Marian Finucane Show, Sunday 12 January search for “Life on Mars” (18 minutes)

Dr Roche was interviewed after reaching a longlist of 1,058 volunteers, selected from over 200,000.   He says that to be chosen for the mission would be like a dream come true.

 “I definitely wouldn't be coming back, it's not up for debate. As soon as I get there I would have to live out the rest of my days there. Because you would be exposed to conditions that no human has experienced before, and there's not enough atmosphere on Mars to protect you from radiation, even with a space suit, my life expectancy would be drastically reduced. The way I look at it, even with a shorter life on Mars, for every day I live on that planet, I would be taking a leap forward for the scientific endeavour of human kind. For me it would be a dream come true.”

That’s the Morning Ireland clip, the shorter of the two. In the longer interview with Marian Finucane, a fellow hopeful Steve Menaa joins Joe Roche and so does his sister Deirdre. She says the family would be devastated if he was selected and he had to go, but on the other hand Joe was always ambitious and he likes to see through the things he starts, and if this is what he wants we'll support him in it.   Steve says “I like my life on Earth but I like a challenge as well. We humans are explorers.”

Greenhouse for growing plants and insects on Mars. As envisioned by the Mars Society.

Asked what they will do for food, Joe says they will grow plants. And for protein, breed insects. Yummy.

When after 5 years the colony reaches full strength, there will be 20 of them, men and women. Will there be children produced? No. Joe says sterilising all the astronauts should be considered, and it's exciting that there is that ethical discussion. Sacrifice in the cause of science is mentioned, but Joe says it's easy to sign up for this if you're passionate about it, he's not sure sacrifice is the word; it could actually be called selfish, he admits. 

It would be good to work with NASA or ESA and have a return trip, but those agencies’ plans are 30 years in the future. “I'm 30, and if I go, I go now”.

Mental illness?

There will be no Skype. Radio waves will take over 3 minutes to travel in each direction.  (Up to 20 minutes in each direction, I would say, depending on the two planets’ relative positions.)

In neither of these interviews is anything said about the psychology of isolation. According to this Guardian blog, those sent to live and die on the red planet face untold risk of mental illness.

And the 24-hour Big Brother show that’s going to fund the project will heap more pressures on. 

Will it be reality TV, or a horror movie, is my question. And which will bring in the bigger bucks?

Celebrating Isaac Newton's birthday

Which world changing person’s birth have you been celebrating today? On Christmas Day 1642 Isaac Newton was born. His work laid much of the foundation for our modern understanding of the universe by uncovering the force that keeps it together, and showing it’s the same as what makes an apple fall. He formulated what are known as Newton’s three Laws of Motion. He may have been the greatest scientist ever.

To divert you from the day’s excesses may I tempt you to Deborah Byrd’s Earth Sky blog where you'll find links to the laws of motion as well as Newton’s revelations about gravity.

But the most extraordinary revelation about Newton is this: that according to some, science wasn’t the biggest thing in his life. What was even more important to him was biblical textual criticism, in which he excelled, and his unitarian belief (no trinity) which he had to keep to himself, for fear of being expelled from Cambridge University.  A couple of years ago I attend a fascinating lecture on this.

Of logarithms, fraudsters and exoplanets

Pristine log tables. Well-thumbed would be better.

Suppose you need to multiply 263.4 by 351.2 you would nowadays use a calculator, but when I was at school in the 1960’s we used logarithms.  Logs to their friends.  In a book of log tables we would look up the log of 263.4 and the log of 361.2, add the two logs together, then look up the result in an antilog table, and bobs your uncle. Not as quick as a calculator but easier than multiplying.  We each carried around a well-thumbed book of log tables, yet one thing we all failed to notice was that the pages for numbers beginning with 1 were more well-thumbed than pages for numbers beginning with 9.  Or if we noticed we never asked ourselves why. But a character called Newcomb did, in 1881. For he it was that discovered Benford’s law and in the process proved Stigler’s law (Stigler’s law being that in science, laws are always named after the second person to discover them; and in this case the second person to discover the law was Benford.) 

Benford's law states that in most lists of data, the first digits of the numbers follow a pattern of probability, where 1 is the commonest first digit, and 9 the least common.  Take for example a list giving the heights of the tallest buildings. Almost one third of the buildings in the list will have a height whose leading digit is 1. Next most frequent in the leading position is the digit 2. And so on, till you come to 9 which is likely to be found as the leading digit in only 4.6 per cent of buildings.

Or rivers. Look at Wikipedia’s list of world rivers longer than 1000 km. You'll find a table giving length in km, length in miles, drainage area in km², and average discharge in m³/s. At my rough count, it contains five hundred numbers, of which only 18 start with a 9.

Fraudsters

Benford's law also applies to financial data, a fact unknown to most fraudsters, who tend to suppose that the best way to insert phoney entries into a list of expenses or transactions, is to make up numbers at random, with as many starting with 9 as starting with 1. But Benford’s law soon finds them out. And the spooky thing is, it matters not whether the transactions are in pounds, euros or dollars.

Exoplanet with two suns and an exomoon. But is it real?

I've read the Wikipedia article on Benford’s law which purports to explain why this should be so,  and I can't follow it as it involves high level maths.  But no matter, all this is by way of working out how many exoplanets have been discovered.

I recently mentioned that the Kepler mission found over two thousand planets orbiting other stars. Now it's important to note that these haven't actually been seen in the usual sense of the word. They have been seen in strings of data, indicating very slight periodic dimmings in the brightness of a star. From this data scientists have inferred size of a planet, distance from the star, and other factors.

But inferences can be wrong. In some cases the data could perhaps result from another phenomenon entirely, and have nothing to do with a planet at all.

And according to this week’s New Scientist, that’s where Benford’s law comes in. 

Thomas Hair at Florida Gulf Coast University wondered if Benford's law would hold true even beyond the solar system, and examined data from an online catalogue that lists 755 confirmed exoplanets and nearly 3500 planet candidates. Planet masses are given in multiples of Earth's or Jupiter's mass. He found that whichever of these two units is used, the figures closely fit Benford's law, making it highly likely the supposed planets really are out there. "The close fit with Benford's law gives a confirmation to experts' belief that most of the candidates are valid," he says. 

I wish I still had my log tables so I could check that well-thumbed business for myself. I looked in vain on the web for an image of a used copy to put at the top of this post. For fun, I've spent the last half hour reminding myself how to use logs. If you too last used them in the 1960’s take a look.

Of Little Red Riding Hood and horses' hooves

Horse's rear hoof.
It evolved from the middle toe.

Evolution has supplied horses with limbs modified for running,  as well as a special feature for locking their knees allowing them to stand for long periods, and a hoof which evolved from an extruded middle toe.  These features enabled the horse to survive on open grassland by successfully fleeing from predators.   Now here's the crux. All this is equally true of a hoofed South America mammal called a litoptern, which went extinct between two and five million years ago, and is unrelated to the horse. It too, lived on open grassland and in order to successfully flee from predators evolved those very same features, even including that middle toe which evolved into a hoof. This I learnt some years ago at a lecture about convergent evolution.  The point being that evolution, when confronting similar challenges, has an uncanny knack of arriving at similar solutions, even at widely separated times and places.

Which brings me to folk tales about wolves.

“The Wolf and the Kids" is a tale popular throughout Europe and the Middle East. A nanny goat warns her kids not to open the door while she is out in the fields, but is overheard by a wolf. When she leaves, the wolf impersonates her and tricks the kids into letting it in, whereupon it devours them. Versions of this tale occur in collections of Aesop's fables, in which a goat kid avoids being eaten by heeding the mother's instruction not to open the door, or seeks further proof of the wolf's identity before turning him away.

The tale may be new to you, but you doubtless know by heart the tale of Little Red Riding Hood. She sets out for her grandmother’s house with a basket of goodies, but a big bad wolf finds out about her itinerary, gobbles up grandma and disguises itself to lure the little girl to her doom. "What big teeth you have!" Little Red Riding Hood remarks before the wolf devours her.

 Little Red Riding Hood at the
door to Grandma's house.
Late 19th century trade card.

Lets look at the parallel between the two stories.  In each we have a wolf who gets dinner by impersonation – of the nanny goat in the first story, and of the grandma in the second.  “The Wolf and the Kids" probably originated in the 1st century AD. “Little Red Riding Hood” arose about a thousand years later. Durham University anthropologist Dr Jamshid Tehrani borrows evolutionary analysis from biology to study similarities among folktales, and claims to show that “Little Red Riding Hood” is descended from “The Wolf and the Kids”. Moreover, “Little Red Riding Hood” evolved from this root once in Europe, and again, quite independently, in Africa.  So, like the horse’s hoof, Little Red Riding Hood has it seems evolved twice.  Dr Tehrani himself draws the parallel with convergent evolution: “The fact that Little Red Riding Hood 'evolved twice' from the same starting point suggests it holds a powerful appeal that attracts our imaginations” he says. 

His article appeared in the open access journal PLOS ONE. If you can follow it all, you're a better man than I am, but luckily there’s a press release, and a very readable account from NBC News.

The best-known version of Little Red Riding Hood was published by the Brothers Grimm 200 years ago, based on a 17th-century story by the Frenchman Charles Perrault who distilled it from oral retellings in France, Austria and northern Italy.  You'll find both on the University of Pittsburgh site along with six other related stories,  which folklorists group together and classify as tales of type 333 in the Aarne-Thompson-Uther system.

Dr Tehrani traces the ancestry and development of Little Red Riding Hood by observing features such as: is the victim single or a group of siblings, goat or human, eaten in their own home or a relative’s.  I found out a bit about classifying folktales when I researched the story of King Midas and his asses ears, a couple of years ago.

That's all I want to say about wolves, but I should have told you more about the lecture on convergent evolution.  One of the first I ever attended in Cork, in December 2005, it was by the Cambridge Professor Simon Conway Morris and his talk explored the heretical suggestion that  evolution has a destination, or even a destiny.  He had recently published his book Life’s Solution – Inevitable Humans in a Lonely Universe,  and argued that in the light of what we know about convergent evolution we should expect intelligent extraterrestrial life, if we ever come across it, to be strikingly similar to ourselves.
 

Are we poised for a jaw dropping discovery?

In my bones I feel that searching for extra-terrestrial intelligence is slightly loopy. Yet many leading scientists, especially at the SETI Institute, engage in the search and sustain their hopes that a sign of intelligent life will one day manifest itself. Radio signals are the usual target, but the lights of alien cities have also been canvassed.

The foregoing is only a digression, since I really wanted to talk about the prospects of finding any sort of life in the universe. An editorial in last week’s New Scientist suggested that if life is common in the universe, we will have found signs of it by the middle of the next decade, “a truly jaw-dropping discovery”.

This prediction of finding signs of life within 12 years or so is based on the NASA Kepler spacecraft’s hunt for habitable exoplanets. These are defined as rocky planets, roughly Earth-sized, orbiting other stars in the habitable zone where water is likely to be liquid.  For three years (finishing last May when the camera malfunctioned) Kepler surveyed a tiny patch of the Milky Way. Even though using an inefficient detection method, it found over two thousand planets, a handful of which seem Earth-like. 

Optimists, extrapolating these results to the whole sky, say it looks certain that our galaxy is home to billions of Earthlike planets.  There are pessimists though. One posted a comment to the New Scientist website claiming Kepler has not found a single earth size planet in the habitable zone.

Paul Davies: life on earth
may have been a fluke

Kepler's successor, the Transiting Exoplanet Survey Satellite, is due to launch in 2017. It's being designed to search for the most promising exoplanet targets for next-generation studies. Restricting its search to nearby stars, it will scour the sky for small rocky worlds, and is expected to find hundreds. Future instruments such as the James Webb Space Telescope and the proposed StarShade mission will follow up these discoveries, probing the planets' atmospheres for signs of life. For example, to an alien astronomer, the oxygen, ozone and methane in Earth’s atmosphere would be a giveaway, because these gases are unstable, so their abundance here would indicate their being continually replenished by life.  So these gases, if present in an exoplanet’s atmosphere, would be an indicator of life as we know it; whilst certain other unstable gases could, by the same logic, be evidence of weird life.

A few comments about New Scientist’s expectation of a truly jaw-dropping discovery. First, notice their caveat “if life is common in the universe”. Many argue that life is probably very rare in the universe. If so, most (perhaps all) of those billions of Earthlike planets could be completely sterile.

Paul Davies (a guru of mine) is fond of saying that fifty years ago scientists used to say life was very unlikely; and now the fashion is to say it's very likely … yet nothing has changed: we're just as ignorant now about what causes life to arise as ever we were.  Here's a review of his 2010 book The Eerie Silence.

Next, if scientists succeed in analyzing a planet’s atmosphere and conclude “wow, life!” they won't, from that data alone, be able to tell intelligent life from microbes. But no matter, to me that would be jaw dropping enough.  Of course you can be sure that the SETI radio antennae will immediately be trained on any such planet. That may be loopy but it has to be done. 

"Comments can be bad for science"

"Comments can be bad for science" is a surprising statement from Popular Science, explaining why their website PopularScience.com, has shut comments off.

This magazine devoted to science and technology news was founded in 1872, and is “committed to fostering lively, intellectual debate as we are to spreading the word of science far and wide. ”

But they say the problem is that trolls and spambots have overwhelmed intellectual debate, and diminished their ability to spread the word of science. “It wasn't a decision we made lightly.” They claim research points to the depressing conclusion that ignorant and vituperative comments can skew popular perception of issues such as climate change. Full story here.

PopularScience.com is a site I like to keep an eye on.  For example a recent article on How Do You Dispose Of Chemical Weapons?

Syrian soldier in gas mask from PopularScience.com
(Wikimedia Commons)

What would happen if you set fireworks off in space?

This question may not previously have occurred to you, but now that it has, you probably welcome the following information:

(1)    They would explode. Oxygen is not necessary. Fireworks have an oxidizer, and a reductant.  (Sorry can't elaborate.)

(2)    The picture shows fireworks being let off in the near vicinity of the Earth and the shards arcing back down as in any normal fireworks display. But suppose you went a long way off into inter-planetary space before letting your firework off, then it would be different.  The shards would continue whizzing outwards pretty much in a straight line forever, faster than on Earth, without slowing. This is because of no atmosphere and little gravity. The only factor that would inhibit this effect would be the gravitational attraction of Jupiter or the Sun. Or some other planet, if nearby. The nearer, the more pronounced an arc there would be towards it.

(3)    The colour would be disappointing. The reaction that imparts a rocket’s metals and metal salts with enough energy to display pretty colours requires oxygen. Unless your fireworks were specially designed for bursting in space, their colours would quickly fizzle out.

(4)    The burst would be completely silent. No atmosphere means no medium to propagate sound waves.

(5)    And by the way you would need to consider carefully how to light your firework. A match, I'm sure, does need oxygen, so my advice would be to provide yourself with a glowing electric filament.

Stefan Bossmann, a chemist and rocket enthusiast at Kansas State University, supplied the foregoing to popsci.com a popular science website. Though he forgot to mention points (2) and (5).

Will we see waves on Saturn's moon?

Waves on Lake Superior, generally considered the largest freshwater lake in the world by surface area, and very nearly as large as Ireland. Will we see waves like these on the Sea of Ligeia? Named after one of the sirens in Greek mythology, this sea is half as large again as Lake Superior and is located on Saturn’s moon Titan. It's filled not with water but liquid hydrocarbons, such as ethane and methane. Here's an image of it compared to a map of Ireland on the same scale (as near as I can estimate it).

The image is a false-colour mosaic of radar images obtained by NASA’s Cassini spacecraft between February 2006 and April 2007. What Cassini will look for next is waves on the surface of this sea. The NASA website says this will be on May 23, 2013.

So did Cassini detect waves last month or not? As yet I can find no account of this. Does all this make the hairs stand up on your neck? Mine do. More spooky thoughts about Titan.

Ligeia Mare is one of the many seas and lakes that bejewel Titan's north polar region, and is the second largest known body of liquid on Titan.

Discarded cicada shells

Another cicada photo. Albert sent this one of their discarded shells in New Zealand. He says “I thought the empty shells were actually critters that could jump up at me. It was only later that I learnt that what I had been photographing were nothing more scary than empty cicada shells!” The shells’ owners were not necessarily dead. After emerging from underground the cicadas molt (shed their skins) on a nearby plant for the last time and emerge as adults. The abandoned exoskeleton remains, still clinging to the bark of trees, as here.  More about their life-cycle in Wikipedia.

Can cicadas calculate prime numbers?

Photo: Tom Wildoner

In the US the 17-year cicada hatch of 2013 is in full bloom. Millions of crimson-eyed critters and their otherworldly din, I've seen them described as. They showed up yesterday in Carbon County, Pennsylvania – the photo comes from EarthSky. These 17-year cicadas live out most of their long lives as nymphs underground, but, each 17 years, they crawl out of the ground for a three-to-four-week festival of singing and mating. Afterwards, they die. Why every 17 years? Because they are mathematicians, that’s why. They recognise 17 as a prime number and they use it to elude their predators. 

It works this way. Cicadas are easy prey for birds and wasps. Now it turns out that predators commonly have 2-to-10-year population cycles. Imagine a cicada species with a 12-year cycle: it would be a feast for any predator with a 2-, 3-, 4-, or 6-year cycle (factors of 12).

On the other hand, Stephen J Gould reasoned in a famous essay that a cicada that emerges every 17 years and has a predator with a 5-year population cycle will only face a peak predator population once every 85 (5 x 17) years.

Advantage of prime numbers 

This gives an enormous advantage to cicadas that know how to calculate prime numbers.  Some biologists however claim that advanced number theory is well beyond the cicadas insect-sized brain and suggest instead that the pattern emerged as a result of Darwinian natural selection: cicadas that matured in easily divisible years were gobbled up by predators, and simply didn’t live long enough to produce as many offspring. Those who, by chance, had long, prime-numbered life spans fared best, survived longest, and left the most offspring, becoming the dominant variation of the species. It seems there are now at least fifteen distinct populations of periodical cicadas. Cicada emergence is tightly timed, with the bulk of the insects emerging within a span of a few weeks. Any cicada that tries to break the pattern is highly likely to have her offspring gobbled up.

I first became aware of this cicada prime number behaviour a few years ago through an In Our Time episode on prime numbers which I highly recommend. It included my guru Marcus du Sautoy.

In another radio programme I heard the biologist Simon Conway Morris pour cold water on cicadas and prime numbers, but he didn't elaborate his reasons.

Mars: it's snowing - and microbes could have lived here

Still my favourite Mars picture. Cape St Vincent, one of the cliffs of Victoria crater. Credit: Nasa/Reuters

It's snowing on Mars – yes really, or at least it was on 27 January.  Very gently, and the snow doesn’t settle - not these days, anyway - but instead vaporises into the thin atmosphere long before it reaches the ground.

I recommend an article by Ian Sample, the Guardian’s science correspondent, for more about snow on Mars and other amazing data being sent back by NASA’s rovers there.

Rock formations on Mars

Take these two rock formations.  On 12th March NASA published these images from two different sites, which provide evidence of ancient watery environments, one hospitable to life, the other not. Before I say more, lets pause for a little gasp that we actually have pictures like this. Gasp.

That's over then. The image on the right, says NASA, indicates a once habitable environment, not too acidic or alkaline, with chemical gradients that would have created energy for microbes, and a distinctly low salinity, which would have helped metabolism if micro-organisms had ever been present.  Data from several instruments on the Curiosity rover all support this interpretation. What we see in the image are very fine-grained sediments.

Too extreme for life

The rock on the left on the other hand is evidence of an environment that is thought not to have been habitable.  NASA reaches this conclusion due to various factors. One is the extreme acidity of the water, another is extreme salinity which would have impeded metabolism.  Moreover, if any micro-organisms had ever been present, too little energy would have been available, due to very limited chemical gradients.  This rock, scientists think, was formed from sulphate-rich sandstone, and the particles were in part formed and cemented in the presence of water; and the bumps on the rock face were formed in the presence of water. 

As a footnote, we should recall that the Antarctic Lake Vida tells us to be cautious before saying “life couldn’t survive here”.  In November microbes were found thriving in conditions of extreme salinity and cold.

The two rock images have been adjusted to look as they would if they were on Earth.  The one on the right puts me in mind of a seaside rock pool but sadly that’s an illusion, there's no water there now.

See NASA Jet Propulsion Laboratory for more particulars of these two images and how NASA scientists interpret them.

Finally, in all the excitement we mustn’t forget that habitability is not the same thing as life. Here's a link to a discussion of Is there life on Mars?, and why after years of discovery the question still eludes us.