Dynamical thinking — thoughts and ideas on science, etc

Solo planets and Byron’s Darkness

Wed, 14 Nov 2012 20:14:54 +0100

Today solo planets — planets without a mother star, alone in space — are in the news, because one has been reported discovered:
http://arxiv.org/abs/1210.0305

Some people call these objects rogue planets, but I don’t see why they are ‘rogues’. The one in the report is quite large - 4 to 7 Jupiter masses, but in principal Earthlike ones too ought to exist; they are just more difficult to spot.

"If this little object is a planet that has been ejected from its native system, it conjures up the striking image of orphaned worlds, drifting in the emptiness of space," study leader Philippe Delorme, of the Institute of Planetology and Astrophysics of Grenoble in France, said in a statement.

But what I haven’t seen reported is that this is a striking example of science following poetry. Compare the above image with Byron's 'Darkness'. To me it seems that the poem discusses precisely this situation, of what would happen to the Earth if ejected from its orbit and expelled from the Solar System:

I HAD a dream, which was not all a dream,
The bright sun was extinguish’d, and the stars
Did wander darkling in the eternal space,
Rayless, and pathless; and the icy earth
Swung blind and blackening in the moonless air
Morn came and went—and came, and brought no day,
And men forgot their passions in the dread
Of this their desolation: and all hearts
Were chill’d into a selfish prayer for light:
And they did live by watchfires—and the thrones,
The palaces of crowned kings—the huts,
The habitations of all things which dwell,
Were burnt for beacons; cities were consumed,
And men were gathered round their blazing homes
To look once more into each other’s face
Happy were those who dwelt within the eye
Of the volcanoes, and their mountain-torch:
A fearful hope was all the world contained;
Forests were set on fire—but hour by hour
They fell and faded—and the crackling trunks
Extinguish’d with a crash—and all was black.
The brows of men by the despairing light
Wore an unearthly aspect, as by fits
The flashes fell upon them; some lay down
And hid their eyes and wept; and some did rest
Their chins upon their clenched hands and smiled;
And others hurried to and fro, and fed
Their funeral piles with fuel, and look’d up
With mad disquietude on the dull sky,
The pall of a past world; and then again
With curses cast them down upon the dust,
And gnash’d their teeth and howl’d: the wild birds shriek’d,
And, terrified, did flutter on the ground.
And flap their useless wings; the wildest brutes
Came tame and tremulous; and vipers crawl’d
And twined themselves among the multitude,
Hissing, but stingless—they were slain for food:
And War, which for a moment was no more,
Did glut himself again:—a meal was bought
With blood, and each sate sullenly apart
Gorging himself in gloom: no love was left;
All earth was but one thought—and that was death
Immediate and inglorious; and the pang
Of famine fed upon all entrails—men
Died, and their bones were tombless as their flesh;
The meagre by the meagre were devour’d,
Even dogs assail’d their masters, all save one,
And he was faithful to a corse, and kept
The birds and beasts and famish’d men at bay,
Till hunger clung them, or the dropping dead
Lured their lank jaws; himself sought out no food,
But with a piteous and perpetual moan,
And a quick desolate cry, licking the hand
Which answer’d not with a caress—he died.
The crowd was famish’d by degrees; but two
Of an enormous city did survive,
And they were enemies: they met beside
The dying embers of an altar-place,
Where had been heap’d a mass of holy things
For an unholy usage; they raked up,
And shivering scraped with their cold skeleton hands
The feeble ashes, and their feeble breath
Blew for a little life, and made a flame
Which was a mockery; then they lifted up
Their eyes as it grew lighter, and beheld
Each other’s aspects—saw and shriek’d, and died—
Ev’n of their mutual hideousness they died,
Unknowing who he was upon whose brow
Famine had written Fiend. The world was void,
The populous, and the powerful was a lump,
Seasonless, herbless, treeless, manless, lifeless,
A lump of death—a chaos of hard clay.
The rivers, lakes, and ocean all stood still,
And nothing stirr’d within their silent depths;
Ships sailorless lay rotting on the sea,
And their masts fell down piecemeal; as they dropp’d,
They slept on the abyss without a surge—
The waves were dead; the tides were in their grave,
The Moon, their mistress, had expired before;
The winds were wither’d in the stagnant air,
And the clouds perish’d; Darkness had no need
Of aid from them—She was the Universe!

Cartwrightia cartwrighti

Wed, 27 Jan 2010 19:31:00 +0100

I had no idea I share my name with the scarab beetle shown above; a beetle, moreover, described in the very year of my birth. To give it its full title, it is Cartwrightia cartwrighti Cartwright, 1967. This beetle is pretty special in taxonomy because the genus is Cartwrightia, species cartwrighti and discoverer Cartwright. The etiquette is you don't name the species for yourself, so how did this unique combination of names come about?

The 1967 paper with an illustration and the description of the species cartwrighti from its holotype [1], by the man himself, Oscar L. Cartwright, who devoted his whole career to scarab beetles [2], explains that Cartwrightia was named after him in 1958 by a colleague, which is common. Then he himself in 1967 found two new species of beetles in this genus, one of which, from the edge of the Amazon in Bolivia, he named after his brother: “Cartwrightia cartwrighti is named after my brother Raymond Kenneth Cartwright, who, though not an entomologist, accompanied me and served as guide on many pleasant and productive field trips” [1]. Thus this lucky beetle got its name...

[1] O. L. Cartwright, Two new species of Cartwrightia from Central and South America (Coleoptera: Scarabaeidae: Aphodiinae), Proceedings of the United States National Museum 124, 1-8, 1967.

[2] P. J. Spangler, Obituary. Oscar Ling Cartwright. Proceedings of the Entomological Society of Washington 87, 690-698, 1985.

How far’s the horizon?

Mon, 30 Nov 2009 13:04:00 +0100

Recently my sister and mother moved into their new place in Malaga. It’s about 30 km from the sea, which you can see clearly on a fine day. The house is at about 900 m altitude. So how far away is the horizon, in fact?

Well let’s see: we need to construct the line tangent to the circle of the Earth (see diagram); cos a=R/(R+h) and D=R.a, so that makes D=R arccos R/(R+h).

R is 6400 km and h is 0.9 km, which gives D=107 km. That means we’re looking across 30 km of land and nearly 80 km of the Mediterranean sea, which is about half way to the African coast. To see the far coast, i.e. have the horizon about 190 km away, I’d need to get to about 2800 m altitude (in fact the Sierra Nevada gets to over 3400 m, and the Atlas mountains on the African side stick up and make the job of seeing Africa easier). If I were on the beach, with an altitude of h=2 m, the horizon would drop right down to 5 km, and to see twice as far, I need to be at an altitude of around 8 m, which is why the crow’s nest in a ship comes in handy.

Arago must known these numbers by heart from his time surveying the meridian.

Chinese eclipse

Wed, 22 Jul 2009 19:18:59 +0200

I went to China hoping for a good eclipse, and, as the pictures show, it was rained off and clouded out. It just got very dark at totality. The best I could do was these photos of the partial phase just after totality, when the Sun appeared briefly through the clouds. The last picture is a satellite photo of the eclipse right about where I was.

Minimal modelling in science, art and literature

Sun, 24 Aug 2008 13:13:17 +0200

To me the essence of scientific thinking is to be able to cut away all irrelevant detail of a question to arrive at its kernel; to make, as Einstein put it, a problem as simple as possible but not more so. This gives one a minimal model, either conceptual or computational, of the phenomenon one is interested in.

Recently I have argued in a paper on Hokusai’s Great Wave that he worked in this way in his art, so I found the quote below about Jane Austen’s writing fascinating; it suggests that in her writing she was applying this same minimalist method to literature:

“Someone asked why Austen has so little detail, and I replied that she cuts away all the irrelevant detail of what someone wore or their messy emotions, and keeps us to the generalized psychological and moral patterns, types of people and kinds of statements not overloaded with particulars so that we can recognize these are variants of our own experience and stand outside them all the while remaining alert to and yet somewhat cauterized against all the aspects of their stinging pain and humor.

We don't care what color the sofa is upon which Fanny sits. It doesn't matter what color Mrs Norris's eyes are--or even what is her first name.”

Ellen Moody
Sense and Sensiblity, Volume I, Chapters 10 - 12