Then the outside hardened into a rock-crust full of bumps and hollows .sx The latter gradually filled up again with water from the clouds and formed the oceans .sx Finally , when the temperature had fallen to a certain point ( which we will not specify , because we don't know it ) , minute portions of the crust began to wriggle .sx They had .sx come alive .sx This is .sx supposed to have .sx been in 4,000,000,004 .sx B.C. , or , as time is .sx reckoned in the .sx Cosmos , about five .sx minutes ago .sx After .sx passing through all .sx sorts of forms , life .sx has now reached its .sx highest development .sx ( so far ) in a type which may well be represented by you , Angela , and ourselves , the reader and authors of this veracious little book .sx What has the Sun been doing since the loss of his lingual appendage ?sx The poor fellow has been dying by inches , or perhaps , we should say , by ounces .sx To be strictly accurate , he has been , and still is , losing weight to the tune of four million tons a second .sx For this , though distressing for him , we may be thankful , because it has meant a constant fall in his temperature .sx If he had remained as big and hot as he was in his younger days the human race could never have come into existence .sx As it is , the amount of heat he shoots at us at present is just sufficient to keep us out of the oven on the one hand and the cold-storage refrigerator on the other .sx As soon as the balance is upset , as it will shortly be in the latter direction , we shall be well , we just shan't be any longer .sx By shortly we mean in an hour or two ; but don't be alarmed , Angela , because .sx that is only cosmically speaking ; it will be millions and millions of our years .sx Assuming all this to be correct ( which we should be sorry to do ) , we now see what a very , very small potato modern astronomers make man out to be .sx He has managed to wriggle into existence simply and solely as the result of what one can only call a vulgar brawl between two utterly insignificant heavenly bodies , and .sx before you can say `life' or `Jack Robinson' or anything else that is uttered very suddenly and quickly , he will be gone .sx It is humiliating , Angela .sx We are left with one consolation , and one only .sx Owing to the remarkable efficiency of the celestial traffic regulations , such scraps between star and star as we have described must be very infrequent , and even supposing they do occasionally occur , it is quite possible that none of the others has had exactly similar consequences .sx Thus man may be unique .sx But what is the good of being unique if you're nothing more than a foot of film in a cosmic Hollywood reel ?sx Let us get off this painful subject and talk about light .sx Light comes from the stars .sx Every living star in the sky spends every moment of its time in manufacturing light and flinging it recklessly away in all directions .sx The planets also pretend that they are doing the same thing .sx For instance , to look at that deceptive hussy Venus any fine evening , you might think she was a budding sun .sx But she and all the rest of her crush are really only little tin-pot light-reflectors .sx Ask her to wink , and she couldn't do it to save her life .sx That is the star-test ; if you can't wink you don't count .sx Light is the quickest thing there is .sx It travels at the rate of 186,000 miles a second , which seems an odd , unround sort of number to choose , but there it is and we can't get away from it .sx This is a velocity far greater than that of any terrestrial body except an electron or a speed-cop .sx Sir Isaac Newton thought that a ray of light was a stream of bullets , but we now know that this is wrong ; it is actually a lot of very rapid waves .sx ( This , though right at present , will also , of course , be wrong in a short time .sx ) The fact is , waves are pretty popular with .sx astronomers at the moment .sx Have you ever met an astronomer , Angela ?sx We don't mean in the street or at a football match or the Boat Race ; you might easily have done that without knowing it , because to the outward eye they are much like other men , and few of them to-day wear the distinguishing skull cap and long white beard .sx We mean face to face , say across the tea-table .sx If so , we wonder if you realize what impression you made on him .sx How did he regard you ?sx We can tell you .sx If he was over thirty he regarded you as nothing more than just a complex system of waves , waves of electrons .sx One of the most eminent and popular of our F.R.S.'s has recently said , `What we are finding is waves .sx We are beginning to suspect that we live in a universe of waves , and nothing but waves .sx ' It fairly makes one's head swim , doesn't it ?sx Well , this undulatory idea is no doubt very jolly , but there is a difficulty about it .sx Light may be waves , but waves want something to waggle in , and a few miles away from the Earth's surface there's nothing , only space .sx So some years ago a lot of astronomers held a secret meeting and invented a thing they called the Ether to explain how light gets about the universe .sx Now whatever opinion one may have of astronomers and physicists , it is impossible to deny that they possess imagination , and on this occasion they gave it free rein .sx The result was remarkable .sx To do its job properly the .sx Ether , which was supposed to occupy the whole of space , had to fulfil certain requirements .sx Accordingly they made it harder than steel and denser than lead , yet so perfectly elastic that it offered no resistance to bodies moving through it ; it was also intangible and invisible .sx This was the crowning achievement of modern astronomy before Einstein , with whom we shall deal faithfully in the next chapter but one .sx VI .sx SO IS THE ATOM .sx PEOPLE are accustomed to refer to the atom in slighting terms those of them , that is , who are not scientists .sx The latter never speak of it save with bated breath .sx To take a single instance :sx when assisting at a private view of a new-born infant , admittedly a revolting object , we often , on recovering our power of speech , remark that it is `a quaint little atom .sx ' Yet , though of meagre proportions an atom , in the mature bloom of its beauty , is , to such as can appreciate and love it , incomparably more attractive than the .sx half-baked offspring of the human or , indeed , of any other species .sx Of all creatures , known and unknown , the atom is the smallest .sx It is so small that you cannot cut it in two with a safety-razor blade hence its name .sx You couldn't even try to , because you wouldn't know where it was .sx The modern atom is invisible .sx If this is so , how , you may well ask , do we know that it exists ?sx The answer is , we don't .sx The only thing we do know is that it must .sx It is well to bear this in mind when reading books on the atom ; otherwise you may easily be deluded into imagining that some of these scientists have actually got tame specimens in cages and have been studying their habits for years .sx This is not the case ; none of them has ever seen one , even through a microscope .sx How , then , you may ask again and probably will ask , since , being a girl , you have of course taken sides with that miserable baby in the first paragraph how can we speak of what no one has ever seen as being beautiful ?sx Don't try to hurry us , Angela .sx Be patient , and you shall know all .sx According to the Greek Democritus and as pictured by dear old Sir Isaac Newton , the earlier atom closely resembled a minute bullet and was , for its size , extremely massive .sx Its successor , the child ( heaven help it !sx ) of the modern scientific imagination , is mostly composed of hot air , or , to be more accurate , of space .sx It is , in fact , almost entirely a great little emptiness ; and we may tell you in confidence , Angela , that if it were possible to pump all the space out of the millions and millions of atoms of which you yourself are built up and to squeeze their solid parts .sx together into a single lump , you would be too small to be seen by the naked eye ( which , we may add , would be a pity) .sx Even scientists are really nothing more than glorified gas bags .sx In the middle of this wee space-chamber sits the nucleus if one can speak of sitting where there is nothing to sit on ; perhaps we should say , the nucleus is suspended ; at any rate , there it is .sx The nucleus is made of positive electricity , that is , of real electricity , of electricity that positively is electricity .sx You must remember this and not think of it as composed of lead or iron or gravel or anything like that .sx Let us at all costs avoid the errors of the older philosophers .sx Round and round the nucleus buzz the electrons , made of negative electricity , an inferior brand .sx These busy little bodies cut their circles at a perfectly appalling speed ; yet , though in some cases there are a lot of them , they are so orderly and well-conducted that there is no jostling or crowding , which is really rather wonderful when one considers that their aerodrome often has no lights .sx But they have eyes like cats and can see quite well in the dark .sx Neither the nucleus nor the electrons take nourishment of any description , but the latter require a certain amount of heat to keep up their circulation .sx Not too much , though .sx At excessively high temperatures they get excited , run off the course , and never find their way back again .sx The middle of the Sun , where the thermometer frequently registers fifty million degrees ( Fahrenheit ) in the shade , is full of lonely nucleuses' darting aimlessly hither and thither with piteous cries in search of their lost electrons .sx On the other hand , excessive cold is just as bad for the electrons .sx It makes them numb and sluggish ; their eyes glaze , their pace slackens , and they finally meet an awful death by crashing on the nucleus .sx `Why,' we hear you exclaim at this point , `an atom is just like the Solar Cistern !sx ' You are quite right , Angela , it is ; and this is what makes it so beautiful .sx You see now , don't you , how favourably its perfect symmetry compares with the irregular contours of the infant mentioned at the beginning of this chapter ?sx In fact , in the eyes of a scientist , the baby's single redeeming feature is that , if analysed , it would be found to be composed of atoms ; and no doubt many a one would , with the mother's permission , be more than willing to melt it down .sx VII .sx AND AS FOR EINSTEIN !sx SO far , Angela , it has been pretty plain sailing .sx Some of the figures may have stunned you slightly .sx The idea of a nebula being so remote that its light takes 140 million years to get to us even by the non-stop route at the rate of 669,600,000 m.p.h. seems distinctly far-fetched , while to pretend that our bodies are humming with myriads of little planets is obviously absurd .sx But one expects blows of this kind when dealing with the modern universe ; besides , you needn't believe such statements , you know ; we don't ourselves .sx But , when all is said and done , they are at least understandable ; by raising ourselves on our toes and taking a long , deep breath we can grasp them , in a way .sx In this chapter , however , we are coming to some theories which lie quite outside the reach of the ordinary human intellect , .sx and of which one of our foremost and kindest-hearted scientists has said that unless you are a mathematician you can't possibly hope to grasp them .sx