ALMOST ETERNAL

Auckland Star, Volume LXVIII, Issue 270, 13 November 1937, Page 10 (Supplement)

ALMOST ETERNAL

HAVE you ever stopped to consider what it would cost to

light the world with sunshine if we had to pay for it? It is a matter of rather simple calculation, for measurements of the heat and light from the aun arriving at the earth are constantly being made.

Every square jard of the earth's surface directly exposed to the sun receives, on the average, the equivalent of one 4nd one-half horsepower of energy. We pay our electric light bills in terms of kilowatt liours, so perhaps we should say that the energy falling on every square yard directly under the sun equals oun and an eighth kilowatts. At a cost of but one penny per kilowatt hour, the light nr.d licat bill from the Solar Power Company would amount to £0,000,000,000,000 for an average day of twelve hours!

Such examples give us a little idea of the enormous amount of energy coining from the sun. Here on earth, however, we are tapping a very small part of tlie total energy generated in the solar powerhouse. The earth itself can consume only one two-billionth of the amount of energy being generated and radiated by the sun.

How do we know tbisT We know the size of the earth and its distance from the aim, so tt is easy to compute how much of the sun's total radiation into space can be intercepted by a little planet like the earth.

This, then, makes it possible to calculate the total output from the solar Cowerhouse. It is 343,000,000,000,000,000 llowatts. Evidently the solar dynamos must be running at full tilt, at continuous service. We know of no spare generators that can be cut in on emergency.

It doe* not appear that any of the other planets in the solar system are likely to be habitable, so that ao far as we can see, for every pound's worth of light sent the earth by the sun,

£2,000,000,000 worth go to waste, except for the possible pleasure that may bo derived by some romantic souls in beholding the radiance of Venue, Jupiter and the other planets shining by reflected sunlight. We will leave it to the reader to figure out the cost of this street lighting of the sky.

Just how long the solar powerhouse has been in operation and just how long it will continue to run on this nonprofltable basis we do not know. Judging from the habits and life histories of other stars, the- sun has been at work supplying approximately its present amount of energy for the life of the earth, which has been estimated at something like two billion years.

At present there is no sign that the sun « storehouse of energy will give out for many billion years to come, barring accidents. Of course, if some cosmic catastrophe should happen—such as a dark star falling into the sun—there would quite likely be a short circuit in the solar powerhouse. A few fuses in the solar system would be blown out, and the earth would be put out of business as a consumer.

Let this be no cause for anxiety; it is more than likely that the sun's output will continue throughout the life of the human race and then some. We shall probably go on benefiting by it* light and heat and deriving our source of power from the sun for an indefinite time to come.

Incidentally, all our sources of power and energy here on earth, of course, are but subsidiary power plants to the Solar Power Company. Our most powerful electric light companies are merely retailing for a profit energy which they have received gratia from the sun's super powerhouse.

Millions of year* ago this same sunshine provided the energy for growing the vast tropical forests of the carboniferous era. The carbon in those tree

trunks we are mining to-day in the form of coal, which is shipped to the local power companies for our local source of light and power. Just how long this canned sunshine will continue to make possible night life on the earth is a matter for geologists and mining expert* to speculate about.

Of course, hydro-electric plants do not dodge the issue of an enormous debt to the Solar Power Company, for it is the radiation of the sun falling on the oceans, lakes and streams, that creates the ascending water vapour which condenses into clouds and descends again in rain. Water in the mountain streams again seeks the ocean level, forming rivers that pour in rushing torrents through the giant turbines of hydroelectric power plants.

Meanwhile, our bill for electrical energy from the sun mounts by leaps and bounds. Fortunately we have to create no new bond issue for taking care of the accumulated debts. From the dawn of civilisation to the present day the indebtedness amounts to only f22,000,000,000,000,000.000 —so why worrv ?

The total amount of energy that is constantly being supplied to the earth by the sun is 230 million million horsepower. What, we may ask, is the source of supply that keeps the solar powerhouse going? Concerning this, scientists have advanced many theories. One should not think of the sun as a burn-

ing furnace in any ordinary sense; it is too hot to burn. Burning is an oxidation process. The temperature of the sun is for the most part too hot to allow oxygen to combine with any other element. Furthermore, although the sun weighs two octillion tons—the figure 2 followed by twenty-seven zeros —if it were composed of the hardest anthracite coal and could burn under ideal conditions for perfect combustion with oxygen, calculations show that it could not have kept up its present output of light and heat for more than 1500 years. It could not have supplied the heat of incubation for the human race on such an assumption.

The idea that the source of fuel must come from outside the sun was a point of view held for many years. Some scientists held that the amount of meteoric matter which must be falling into the sun would supply enough kinetic energy to keep up the sun's output. While the idea was at best speculative, fortunately it could be checked against experience.

The earth is one of the sun's bodyguards, circulating around it at a distance of 93.000,000 miles. While rather a lone sentinel, it certainly gets a fair sample of what would be falling into the sun promiscuously from outside space. The number of meteor* hitting the earth or it* atmosphere is a matter of fairly careful estimation based on the actual counts of meteors observed.

Sun's Secret Source Of Energy

The earth by itself can protect only one two-thousand-millionth of the sun's surface from such a cosmic bombardment. Therefore, to get an idea of the amount jf meteoric material falling into the sun we should have to multiply the earth's daily quota of meteors by 2,000.000.000.

Another important factor is that the force of gravity of the sun is twentyseven times that of the earth. This would increase enormously the amount of heat liberated by a meteor as it strikes the sun, as compared with the heat liberated by a meteor falling into the earth's atmosphere.

By making an allowance for all this, it appears that the heat supplied the sun from such outside sources could not have kept the solar powerhouse in operation at its present rate for more than 10,000 years. Thus it is seen that the meteoric hypothesis previously conceived is entirely untenable except as a supplementary supply.

With the failure of an outside fuel supply, astronomers turned their thoughts to the interior of the sun as its own source of energy. Under its ▼ery heavy gravitational force, the sun, in common with all stars, must be continually contracting, and thus increasing the density of its interior. Curiously enough, when a gaseous body contracts it will actually rise in temperature as long as it remains in tie state of a gas. As far back as 1804, Helmholtz applied this idea to the calculation of the amount of shrinkage the sun would have to imdergo per year in order to keep up its present rate of output. He found little more than 200 ft per year was necessary. This is too small an amount to be observed from the earth even with the most powerful telescopic equipment. With the rate of contraction thus calculated, it was a relatively simple matter to lind out how long altogether the sun could be expected 1 to contract and still be a sun. The answer to this question was disappointing. It was ten million years. Meanwhile, geologists were contending that from the rate of deposits of salt in sea water and the formation of sedimentary rocks in the earth, this old planet must have been receiving solar energy at the present rate for at least 100,000,000 years. Recent measurements of the rate of radio-activity taking place in the earth's crust show that the earth's age must be at lea«t twenty times this earlier estimated amount. So the contraction theory has gone with the wind, alon;j with the meteoric hypothesis.

Now modern physics comes to the rescue with the idea that energy may

come from the very material of which the sun is composed. The sun has an abundant supply of hydrogen. Th hydrogen atom is the simplest of -li the elements and appears to be th fundamental building block out of whk* every other element might be made if we knew the trick.

Four hydrogen atoms put together will make an atom of helium. Helhnn is a light, non-explosive gas. Two Iran dred and seventy-five thousand cubic feet of it went into the stratosphere balloon, Explorer 11., that beat th world's record for altitude. But stranttlv enough, one atom of helium weighslesi than the four atoms of hydrogen which could make % it. The sun has heliumin it, but there is not as much of ft a . there is of hydrogen. It i» believed, however, that the sun may be a helium factory, where hydrogen as a nw material is converted into this rarer cat In so doing, a 1 per cent transportation tax goes somewhere to represent the loss in weight that takes place in the process. What becomes of this 1 per cent tax on weight that appears to he extracted?

The beet guess of science is that ft hae disappeared into energy. Here, then may be the mysterious source of supply for solar radiation. • '

Now we can draw an easy breath, for we can see no immediate cause for the solar powerhouse to shut down. We shall not be left in darkness so long as the sun has matter left that can be transferred into energy. At long * a the sun has such a vast number of tons of matter in it, what does it matter if it is radiating away 4,200,000 tons of heat every second?