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Lyle Zapato

Lord Kelvin & The Olympic Water Cube

Lyle Zapato | 2008-08-05.0220 LMT | Entertainment | Technology

In 1887, Lord Kelvin, in a paper titled "On the Division of Space with Minimum Partitional Area", sought a way of partitioning space using a foam of equal-sized cells with a minimum surface area. His solution, known as the Kelvin structure, consisted of repeating tetrakaidecahedra with slightly curved faces.

Stereoscopic photo of a tetrakaidecahedron, constructed out of soldered wire, from Kelvin's 1894 "On Homogeneous Division of Space". (Cross eyes to view in 3D.) Also, I have a paper model approximation of a Kelvin cell available for download [PDF].

It wasn't until 106 years later that Denis Weaire and Robert Phelan discovered (aided by advanced computer software that would have taken millions of years of run time on a standard Victorian era difference engine,) a solution that had 0.3 percent less surface area than the Kelvin structure. However, their solution, the Weaire-Phelan structure, uses two different shaped cells instead of Kelvin's simpler single cell solution.

As the New York Times reports, the wall and roof structure of the new Beijing National Aquatics Center, also known as the Water Cube, is based on the Weaire-Phelan solution to the Kelvin Problem. The building's designer, Tristram Carfrae, tilted the structure 60° to give the surface an almost random look (although it does repeat its pattern). According to this 2004 article, it was for this pseudo-irregular "organic quality" that the Weaire-Phelan structure was chosen over the Kelvin structure, which was originally considered.

The Water Cube during construction.

Lyle Zapato

Lord Kelvin & Color Codes

Lyle Zapato | 2008-07-29.1140 LMT | Technology | Crass Commercialism

In his 1899 speech given after Sir George Stokes read his paper "On the Perception of Colour" at the Victoria Institute, Lord Kelvin casually predicted the future:

Now I spoke of scientific men. There are scientific ladies also—and ladies who are not scientific—and I am sure they will all thoroughly sympathise with scientific men in their appreciation of this beautiful theory.

Sir George Stokes told us that every variety of colour may be produced by the mixture of red, green and violet, and in Maxwell's practical work on the subject of which he spoke, white and black are added in the mixture, white to dilute the intensity of the colour; and black to diminish the total light emitted by a body exposed to sunlight.

Now in these times when ladies are so well occupied with important work that they scarcely have time for shopping, it would be a great comfort to them, if when they wanted a beautiful blue ribbon, they could simply write down on a piece of paper and put it in an envelope and send it to the shop; or a brilliant yellow, no black in it—3 of red, 4 of green, 0 of violet, 2 of white to brighten it up a little and dilute some of the colour. Do not imagine that you will get green by mixing yellow and blue—on the contrary, you get yellow by mixing red and green, as was first taught by Young, enforced by Helmholtz, and splendidly put in practice by Maxwell.

That's right, Lord Kelvin foresaw the common use of color codes on the Web! Kelvin's idea went even further though, to real world color specification via numerical strings. Unfortunately, the average consumer still can't purchase pretty ribbons or other such things custom dyed from an RGBLK string sent to the shop. (I smell a Web 2.0 business potential...)

Lyle Zapato

Lord Kelvin and the "Butterfly Effect"

Lyle Zapato | 2008-07-13.6760 LMT | Random Found Thing

While further researching Lord Kelvin, I came across an interesting quote. The Universe a Vast Electric Organism (George Woodward Warder, 1903) quotes Prof. Garrett P. Serviss -- the author of Edison's Conquest of Mars, which co-stars Lord Kelvin -- in the New York American, May 16, 1903 (bold mine):

"The undulatory theory of energy is carrying everything before it. It is not saying too much to aver that wave motion is concerned in nearly all the phenomena of physical life . . . Think for a moment of what is included in the science of waves. In the air all sounds, all musical harmonies are waves; in the solid globe, all earthquakes are waves; in the ether light, electricity and heat are waves. It is waves that make the stars visible, and yet more mysterious oscillations picture for us on photographic plates marvelous nebulous objects. Lord Kelvin has been credited with the statement that the fluttering of a butterfly's wing sets up vibrations that shake the universe." (p.288)

I've searched for the original quote by Kelvin but have come up empty. The only references to it I can find on the Internet are in Warder and a mention in passing in Science of the New Thought (Erastus Whitford Hopkins, 1904). If anyone can find what statement of Kelvin's Serviss was referring to, please contact me, as this would add chaos theory to the multitude of scientific fields that Kelvin influenced in some way.

According to the Wikipedia article on the "butterfly effect", the connection of butterflies to the idea of sensitive dependence on initial conditions came from Ray Bradbury's 1952 short story "A Sound of Thunder". Granted it's Wikipedia, so it might as well say John Seigenthaler Sr. first came up with the idea, but if that's the accepted wisdom on the metaphor's origin, what shall we make of Kelvin's use of it half a century earlier? Time travel?

[UPDATE 2010-01-28: Looks like it was originally a mosquito, and Kelvin didn't recall saying it.]

Since I don't have Kelvin's original quote, I'll leave you instead with some entertaining figures from Hopkins' book above:


Lyle Zapato

Edison & Kelvin: A Contrast In Cruelty

Lyle Zapato | 2008-01-04.3520 LMT | Technology | Elephants

Wired notes that on this day in 1903 Thomas Edison electrocuted an elephant to death as part of his smear campaign against alternating current, a system in competition with his patented direct current system. As the War of Currents raged, Edison grew increasingly alarmed at the acceptance of AC as the electrical distribution standard, and so set out to scare the public into believing it was too dangerous through a series of publicized animal executions using AC. Topsy the elephant was merely a notable exception in a long string of fried dogs and cats. (Edison also promoted the use of an AC electric chair for human executions, even though he was opposed to capital punishment; such was his desire to tarnish the image of a competitor at any cost.)

It should not surprise readers of this site that the decision that led to AC beating out DC came from none other than the Lord Kelvin.

1895 International
Niagara Falls Commission
The International Niagara Falls Commission, headed by Lord Kelvin (center).

It was Lord Kelvin who headed the 1895 International Niagara Falls Commission that chose Nikola Tesla's alternating current system over other proposals, including the Edison-backed DC system from General Electric, and awarded Westinghouse the contract to construct the hydroelectric generators at Niagara Falls. This highly-visible project showed the practicality of the system and turned the tide in favor of AC.

Kelvin had originally been opposed to alternating current before being swayed at the 1893 Chicago Exposition. His acceptance of Tesla's system actually completed a circuit, since an inspiration for much of Tesla's research was Kelvin's 1853 paper "On Transient Electric Currents". Kelvin, who had long been a promoter of electric lighting -- his house in Glasgow was the first in the world to by fully lit by electricity -- saw in AC the potential to bring about a dream of his, that he reiterated on a visit in 1902 (quoted in The Post-Standard, April 22, 1902, p. 1):

It has been so great, so marvelous, that I hope to live to see the day when a dream I have had may come true. I fervently hope to see the day when we shall have the transmission of electric power over 300 miles with a voltage of 40,000. When I first talked of that fifteen years ago I was laughed at. But with the wonderful transmission of power at Niagara Falls, my dream looks to be near fulfillment in the close future.

And let me tell you American people, there may be a time when the waters will flow no more over that great horseshoe, but instead there will be a beautiful growth of vegetation far more superb than any water flowing in torrents over the precipice, water that will find its way down countless turbines spreading light and power for hundreds of miles in all directions.

Edison's use of violence against animals to undermine Lord Kelvin's choice of AC was viciously ironic given Kelvin's concern for animal welfare. Kelvin, who was a vice-president of the Society for the Protection of Animals Liable to Vivisection, publicly spoke out against animal cruelty. While he did allow that some vivisections might be necessary for the advancement of science in cases where new knowledge might be gained (he later resigned as SPALV vice-president when the Society united with the more hard-line International Association for the Total Suppression of Vivisection,) he firmly held that repeated vivisections merely for the edification of students was "altogether unnecessary" (source).

In a letter to the Scotsman on March 6, 1877 (quoted in S.P. Thompson's The Life of Lord Kelvin), he wrote:

SIR—In your print of this morning I see a report of Professor Rutherford's paper on "The Secretion of Bile," read at the meeting of the Royal Society yesterday evening, when, as president, I was in the chair. As chairman I did not feel that I had the right to express my opinion that experiments involving such torture to so large a number of sentient and intelligent animals are not justifiable by either the object proposed, or the results obtained, or obtainable, by such an investigation as that described by Professor Rutherford. I feel this opinion very strongly, after many years serious consideration of the general question of the advisableness or justifiableness of experiments involving cruel treatment of the lower animals. I trust you will kindly give me this opportunity of expressing it, as my presence without protest yesterday evening might seem to imply that I approved of the experiments which were described.

As to electrocuting animals, this anecdote (recounted in The Elyria Chronicle, Aug. 1, 1906, p. 4) clearly shows that he was against it:

Lord Kelvin once performed a daring experiment before a class of students. In the course of his lecture he said that while a voltage of 3,000 or so would be fatal to a man a voltage of some 300,000 would be harmless. He was going to give a practical illustration on himself, but the students cried out, "Try it on a dog!" Lord Kelvin cast a look of reproach at his class. "Didn't I figure it out myself?" he said quietly, as he walked to the apparatus and safely turned the tremendous voltage into himself.

Kelvin's fondness for his pet parrots, Doctor Redtail and Professor Papagaio, was typical of his concern for animals. S.P. Thompson notes:

Lord Kelvin was very fond of animal pets. His parrots have several times been mentioned. He had a horror of unnecessary slaughter of creatures, particularly of birds. He once seized the arm of a man who, while on board his yacht, was shooting a sea-gull, and he protested indignantly against such wanton cruelty.

In contrast, Edison's proclivity for animal abuse extends even to his arrogant self-promotions, as can be seen in Garrett P. Serviss's Edison's Conquest of Mars, an 1898 sci-fi newspaper serial that was officially authorized by Edison's PR machine. The story, which coincidently casts Lord Kelvin as a supporting player, contains the following scene that would have disturbed Kelvin:


I had the good fortune to be present when this powerful engine of destruction was submitted to its first test. We had gone upon the roof of Mr. Edison's laboratory and the inventor held the little instrument, with its attached mirror, in his hand. We looked about for some object on which to try its powers. On a bare limb of a tree not far away, for it was late fall, sat a disconsolate crow.

"Good," said Mr. Edison, "that will do." He touched a button at the side of the instrument and a soft, whirring noise was heard. "Feathers," said Mr. Edison, "have a vibration period of three hundred and eighty-six million per second."

He adjusted the index as he spoke. Then, through a sighting tube, he aimed at the bird.

"Now watch," he said.


Another soft whirr in the instrument, a momentary flash of light close around it, and, behold, the crow had turned from black to white!

"Its feathers are gone," said the inventor; "they have been dissipated into their constituent atoms. Now, we will finish the crow."

Instantly there was another adjustment of the index, another outshooting of vibratory force, a rapid up and down motion of the index to include a certain range of vibrations, and the crow itself was gone—vanished in empty space! There was the bare twig on which a moment before it had stood. Behind, in the sky, was the white cloud against which its black form had been sharply outlined, but there was no more crow.

Furthermore, The Edison Papers' chronology page has this bizarre entry for April 6, 1877, suggesting the kind of violent work environment Edison fostered: "Laboratory staff's 'pet' bear gets loose and they kill it."

While I can find no record of Lord Kelvin commenting on Edison's public animal executions -- perhaps because Kelvin did not wish to appear biased, as with the incident in the Scotsman letter -- I find it hard to believe that he would have viewed Edison's elephanticidal barbarity, which contributed nothing to the advancement of knowledge, with anything less than abhorrence.

In the end, Edison's scare tactics didn't work; AC won out and elephants now know they have more to fear from monorails than from alternating current.

Lyle Zapato

Start Hoarding Air Now

Lyle Zapato | 2007-06-15.9450 LMT | Nature | General Paranoia

While (unsuccessfully) looking for an original, full source for Lord Kelvin's dire predictions of an end to breathable air, I found an interesting article from 1901-10-09 in New Castle News, quoted at length from a "London letter". It paints a disturbing picture of the vapory, frog-ruled world that mankind must survive in after peak oxygen is reached:


Will the human race and all animal life soon be left without air for breathing? will the world come to an end in the general asphyxiation of every living thing?

Lord Kelvin, the greatest authority today in mathematical physics, asserts that the oxygen supply of the world will be exhausted within the next five centuries.

Oxygen is the real force of the atmosphere so far as man and nearly all air-breathing animals are concerned.

Lord Kelvin has sounded an alarm which has created more discussion in scientific circles than any other pronouncement since Darwin put forth his 'Origin of Species.' No satisfactory reply has so far been offered. It is admitted that, theoretically, the oxygen in the atmosphere is diminishing. Every bucketful of coal in a furnace and every stick of wood in a cook stove burns up a portion of the world's supply of breathing air. How long will the oxygen hold out?

Is there any way in which the extravagant waste of the world's atmosphere can be checked?

Lord Kelvin's conclusions were stated in a lecture recently delivered before the British association for the promotion of science. He has made a study of the subject for many years. He is now past middle age, and ranks as the foremost living physicist.

The following is a summary of the important points of Kelvin's theory:

'The extravagant waste of oxygen by modern manufacturing processes may leave the inhabitants of the earth without air for breathing, and that within a short and calculable time. At the present rate of progress five centuries will exhaust the full supply of the world. This means the exhaustion of oxygen.

'The sum total of oxygen at our disposal is 1,020 millions of tons. Every ton of fuel used three tons of oxygen in combustion. Consequently the burning of 340,000,000 of tons of combustibles will destroy the world's air for breathing. The population of the earth is 1,500,000,000 persons. Each has to his credit 200,000 tons of combustibles. Burn this and we die, not from lack of fuel for keeping warm, but from lack of oxygen for breath. Considering the rate at which manufacturing and commerce are depleting the coal supply, less than 500 years may see the end of the human race.'

Science has rarely offered so strange and so terrible a picture of the end of the world as Lord Kelvin's theory suggests. From various scientific authorities in New York (Hallock, Woodward, Hovey, Van Ingen, Burgess and others) interesting speculation as to the gradual approach of the final catastrophe has been gathered.

With the decrease of oxygen in the air the heat of summer would become intense. This would not be the pitiless, parching heat of the desert. Moisture would hang heavy in the air. Steam would rise from the ground and the sun would be veiled in clouds of vapor.

Plants would spring up and flower in a day and trees grow almost in a night. With time for adjustment, the very luxuriance of vegetation would clear the air again and furnish breath to famished life.

But with the swift rush of Kelvin's calculations the mischief will have been accomplished in three centuries. Alarm will spread too late. As oxygen becomes precious the entire human race will strive madly for some means of increasing it. Every man will conserve his strength, because muscular effort requires the expenditures of much oxygen. Factories will not smoke any longer.

Huge electric plants will distill the seas into air. The banks of the ocean will be crowded with the humanity that comes to it to turn it by alchemy from water to breath. Every year the waters will recede under the drain of electrolyting process.

Man will become more puny with each generation. Death will confront the race and pride of power and trade and achievements in art and learning will give way to a desperate struggle for life.

Certain animals, on the other hand, will thrive apace. Huge and brilliant fishes will swim the sluggish streams. Serpents will grow to monstrous sizes and great frogs will croak in the swamps. All the lower nature may reach its flower again before the death of man, as it did before his birth.

The sturdiest of the human species will survive longest. Scarcely on the last day will the last men be able to distinguish the faces of each other in the thick vapor. They will move about in the dense atmosphere with slower and slower steps. A torpor will creep over them and they will die.

Professor William Hallock, department of physics and secretary of the faculty, Columbia university, asked about Lord Kelvin's theory, said:

'Lord Kelvin's contention rests upon a sound basis. It is true that modern manufactories are consuming fuel in larger amounts than the processes of nature now produce it.

'This combustion locks up practically that portion of the world's oxygen which was freed originally in the slow formation of this fuel through unknown ages.

'If we continue to use up our known supply of oxygen at the present rate, without in some way getting the stock reinforced, then our descendants must die of asphyxiation. But nature may in some hidden way discover a means of increasing the supply of oxygen. There may be sources of supply yet unknown to us. Man may invent an artificial process of freeing oxygen from its combinations. Or, lastly, man may become a cold-blooded animal and capable of existing upon an infinitesimal supply of oxygen.

'Vegetation upon the earth would probably have to be swept away before our supply of breathing air gives out. In that case it is a problem whether man would not starve to death before asphyxiation came upon him. Personally I do not anticipate any such catastrophe. It is one of those things interesting to speculate upon, because it is remote enough not to alarm us a great deal.

'One can always hope that something will happen before worst comes to worst.

'As animal life is now constituted it cannot live without oxygen. Vegetation, on the other hand, lives upon carbonic acid gas, which is useless to animals. This forms the main distinction between animal and vegetable life. Each supports a laboratory which works for the subsistence of the other.

'Fish and other cold-blooded animals live on an infinitesimal amount of oxygen. They use it only in muscular effort. Their body heat is the same as that of the element in which they live. Man, on the other hand, is not content with enough oxygen for this. He lives in a mean animal temperature of 98 degrees. he uses up a wasteful amount of oxygen in keeping his body temperature at 98 degrees. It is quite within the range of possibility that evolution may change this.'

UPDATE 2007-06-22: I have found a reference to Kelvin's original paper ("on the Fuel and Air Supply of the Earth", read at a meeting in 1897) that started all this, but it apparently was never published in full. For more details, read the "On the End of Free Oxygen" page.

Lyle Zapato

An Open Letter To Archie McPhee

Lyle Zapato | 2007-02-01.6270 LMT | Crass Commercialism | Letters

Dear Mr. McPhee,

Your company, Accoutrements, is well known for its exclusive line of action figures based on famous historical figures, common folk of interest, and proud indigenous hominoids. However, I have noticed one glaring omission in your otherwise well-rounded collection:

Why is there no Lord Kelvin action figure?

Besides developing the science of Thermodynamics, being instrumental to the unification of diverse fields of science under the aegis of Physics, and mapping the way for Relativity and Quantum Mechanics with his identification in 1900 of the two "Nineteenth-Century Clouds" hanging over the field, Lord Kelvin was the Kevin Bacon of Victorian science and technology, playing roles both minor and profound in most important developments of his time.

Consider some of his many claims to fame:

  • Was admitted to university at age 10, published his first mathematical paper at age 16, and was appointed to the chair of Natural Philosophy at the University of Glasgow at age 22, where he stayed until his death at age 83
  • Was a champion rower in his youth and later in life traveled the seas in his yacht, the Lalla Rookh
  • First person on Earth to have electric lighting installed in his home
  • Headed the commission that chose AC over DC for national power grids
  • Discovered the material property magnetoresistance, the basis for hard drives
  • Had 70 patents, including an inkjet printer in 1867
  • Invented the technology that allowed for transatlantic communication cables and supervised their laying, thereby fathering the global Information Age that we currently live in
  • Coined the terms "thermodynamic" and "chirality"
  • Has a unit of temperature (the Kelvin), a lunar ridge (Promontorium Kelvin), and a refrigerator brand (Kelvinator) named in his honor
  • Incidentally launched the mathematical field of Knot Theory while exploring the idea that atoms are made of swirling vortices of aether -- a full 100 years before String Theorists proposed similar ideas
  • Defended Panspermia, the theory that life on Earth was seeded by "moss-grown fragments from the ruins of another world"
  • Agreed with Tesla that life on Mars was trying to contact Earth via radio signals (UPDATE See: "On the Martians Signalling Earth.")
  • Is buried next to Isaac Newton

As can be plainly seen, it is a great injustice that someone as notable as Lord Kelvin does not yet have his own action figure. I dare say he even deserves a playset!

With December 2007 marking the Centennial of his passing, now would be an excellent time for you to take the lead and rectify this oversight.

Lyle Zapato
Humble servant of Lord Kelvin.

Lyle Zapato


Lyle Zapato | 2007-01-12.6550 LMT | Announcement

Another reason to celebrate...

2007 is the Centenary Year of Lord Kelvin becoming One with Entropy.

The University of Glasgow, where Lord Kelvin both taught and learned for over 70 years (he was accepted at the age of ten, holding the record for the youngest college student ever until recently, and never left -- quickly working his way up to Professor and eventually Chancellor, all the while professing that he remained a student), is planning to celebrate Lord Kelvin's life and contributions to Mankind (details on page 6 of the UG News Review [1.25 Mio PDF]). Observances there include (and included -- sorry, a bit late with this post):

  • The St. Mungo Lecture, which is a "celebration of the history, culture, humanity and passion which distinguishes Glasgow and its citizens", launched the Kelvin Centenary Year on January 9th.
  • In April, a series of talks by distinguished scientists taking a modern look at Kelvin's work.
  • Kelvin Honorary Degrees awarded on the University's Commemoration Day in June.
  • A one-day meeting to celebrate his achievements some time in autumn.
  • And in closing in December, a one-man performance by science promoter Johnny Ball in honor of Lord Kelvin.

If you can't make it to Glasgow, read Lord Kelvin's statements on the 50th anniversary of his professorship for some insight into what he might say were he there to join in the celebrations.

Lyle Zapato

A Father's Tachyon Transceiver

Lyle Zapato | 2006-08-25.2698 LMT | Technology | Letters

Although it may not seem it at first, Christopher R. Davy's 2001 patent application for The Tachyon Transceiver is the heart-warming, feel-good patent application of the summer.

What is a Tachyon Transceiver? Davy claims:

The Tachyon Transceiver(s) can send or receive a resonance from one point in spacetime to another point in spacetime instantaneously without a relativistic time-delay.

Interesting, but probably not as practical as St. Clair's Remote Viewing Amplifier. As we shall see, however, the real interest here isn't technological, but human.


Lyle Zapato


Lyle Zapato | 2006-03-26.9900 LMT | Announcement | Technology

The Tesla Society has asked me to mention that Nikola Tesla's 150th birthday is coming up on July 10, 2006. Be sure to join in the WORLDWIDE TESLABRATIONS! You still have plenty of time to build your own Tesla coil.

Lord Kelvin thought highly of Tesla, saying that he had "contributed more to electrical science than any man up to his time." It was Kelvin who in 1893 headed the Niagara Falls Commission which chose Tesla's AC technology over Edison's DC.

When Tesla was being mocked by the media for revealing that he received radio transmissions from Mars, Kelvin came to his defense and silenced all criticism by proclaiming himself in complete agreement that Mars was signalling New York, since it was the "most marvellous lighted city in the world" and the only place visible to the Martians.

(Kelvin's proclamation was reported in "Lord Kelvin Believes Mars Now Signalling America", Philadelphia North American, May 18, 1902, Mag. Sec. V, which I haven't yet seen. If anyone knows where to find a copy of this, or any other related reports, please contact me.)

(UPDATE: Lord Kelvin later denied he agreed with Tesla on Martian signals. See: "On the Martians Signalling Earth.")

Kelvin and Tesla also corresponded, as well as exchanging books on electrical science and Vedic philosophy:

15, Eaton Place
London, S.W.
May 20, 1902

Dear Mr. Tesla,

I do not know how I can ever thank you enough for the most kind letter of May, 10, which I found in my cabin in the Lucania, with the beautiful books which you most kindly sent me along with it:--"The Buried Temple", "The Gospel of Bhudda", "Les Grands Inities", the exquisite edition of Rossetti's "House of Life", and last but not least the Century Magazine for June, 1900 with the splendid and marvellous photographs on pp. 176, 187, 190, 191, 192, full of electrical lessons.

We had a most beautiful passage across the Atlantic, much the finest I have ever had. I was trying hard nearly all the way, but quite unsuccessfully, to find something definite as to the functions of ether in respect to plain, old fashioned magnetism. A propos of this, I have instructed the publishers, Messrs. Macmillan, to send you at the Waldorf a copy of my book (Collection of Separate Papers) on Electrostatics and Magnetism. I shall be glad if you will accept it from me as a very small mark of my gratitude to you for your kindness. You may possibly find something interesting in the articles on Atmospheric Electricity which it contains.

Lady Kelvin joins me in kind regards, and I remain,

Yours always truly,


Thank you also warmly for the beautiful flowers.

Lyle Zapato

Panspermia In the News

Lyle Zapato | 2006-01-07.8900 LMT | Nature

A paper to be published on red, cell-like particles that rained over India in 2001 has rekindled interest in panspermia -- the hypothesis that life on earth was seeded from space. The paper's researchers also wrote two unpublished papers on the subject in 2003 that made stronger panspermian claims (#1 & #2).

I'm repeating this story and links swiped from Slashdot only so I can add this quote from Lord Kelvin giving the reasoning behind the concept:

Lord Kelvin

Every year thousands, probably millions, of fragments of solid matter fall upon the Earth—whence came these fragments? What is the previous history of any one of them? Was it created in the beginning of time an amorphous mass? This idea is so unacceptable that, tacitly or explicitly, all men reject it. It is often assumed that all, and it is certain that some, meteoric stones are fragments which had been broken off from greater masses and launched free into space. It is as sure that collisions must occur between great masses moving through space as it is that ships, steered without intelligence directed to prevent collision, could not cross and recross the Atlantic for thousands of years with immunity from collisions. When two great masses come into collision in space it is certain that a large part of each is melted; but it seems also quite certain that in many cases a large quantity of debris must be shot forth in all directions, much of which may have experienced no greater violence than individual pieces of rock experience in a land-slip or in blasting by gunpowder. Should the time when this earth comes into collision with another body, comparable in dimensions to itself, be when it is still clothed as at present with vegetation, many great and small fragments carrying seed and living plants and animals would undoubtedly be scattered through space. Hence and because we all confidently believe that there are at present, and have been from time immemorial, many worlds of life besides our own, we must regard it as probable in the highest degree that there are countless seed-bearing meteoric stones moving about through space. If at the present instant no life existed upon this earth, one such stone falling upon it might, by what we blindly call natural causes, lead to its becoming covered with vegetation. I am fully conscious of the many scientific objections which may be urged against this hypothesis; but I believe them to be all answerable. I have already taxed your patience too severely to allow me to think of discussing any of them on the present occasion. The hypothesis that life originated on this earth through moss-grown fragments from the ruins of another world may seem wild and visionary; all I maintain is that it is not unscientific.

Lord Kelvin, August 1871.