Chapter VI: The Signs of Creation in Light
The Sun is probably the one thing we see most often throughout our lives. Whenever we raise our sight to the sky during the day, we can see its dazzling light. If someone were to come up and ask "What good is the Sun? we would probably reply without even a thought that the Sun gives us light and heat. That answer, although a bit superficial, would be correct.
It is certain that the Sun did not just "happen" to radiate light and heat for us, and it is not accidental and unplanned. The Sun is specially created for us. This great ball of fire in the sky is a gigantic "lamp" that was created so as to meet our exact needs.
Recent research indicates that sunlight has magnificent features that inspires amazement.
The Right Wavelength
Both light and heat are different manifestations of electromagnetic radiation. In all its manifestations, electromagnetic radiation moves through space in waves similar to those created when a stone is thrown into a lake. And just as the ripples created by the stone may have different heights and the distances between them may vary, electromagnetic radiation also has different wavelengths.
THE DIFFERENT WAVELENGTHS OF ELECTROMAGNETIC RADIATION
The analogy shouldn't be taken too far however because there are huge differences in the wavelengths of electromagnetic radiation. Some are several kilometers long while others are shorter than a billionth of a centimeter and the other wavelengths are to be found in a smooth, unbroken spectrum everywhere in between. To make things easier, scientists divide this spectrum up according to wavelength and they assign different names to different parts of it. The radiation with the shortest wavelength (one-trillionth of a centimeter) for example is called "gamma rays": these rays pack tremendous amounts of energy. The longest wavelengths are called "radio waves": they can be several kilometers long but carry very little energy. (One result of this is that radio waves are quite harmless to us while exposure to gamma rays can be fatal.) Light is a form of electromagnetic radiation that lies between these two extremes.
The first thing to be noticed about the electromagnetic spectrum is how broad it is: the longest wavelength is 1025 times the size of the shortest one. Written out in full, 1025 looks like this:
A number that big is pretty meaningless by itself. Let's make a few comparisons.
For example, in 4 billion years (the estimated age of the Earth) there are about 1017 seconds. If you wanted to count from 1 to 1025 and did so at the rate of one number a second nonstop, day and night, it would take you 100 million times longer than the age of the earth! If we were to build a pile of 1025 playing cards, we would end up with a stack stretching halfway across the observable universe.
This is the vast spectrum over which the different wavelengths of the universe's electromagnetic energy extend. Now the curious thing about this is that the electromagnetic energy radiated by our Sun is restricted to a very, very narrow section of this spectrum. 70% of the Sun's radiation has wavelengths between 0.3 and 1.50 microns and within that narrow band there are three types of light: visible light, near-infrared light, and ultraviolet light.
Three kinds of light might seem quite enough but all three combined make up an almost insignificant section of the total spectrum. Remember our 1025 playing cards extending halfway across the universe? Compared with the total, the width of the band of light radiated by the Sun corresponds to just one of those cards!
Why should sunlight be limited to such a narrow range?
In Energy and the Atmosphere, the British physicist Ian Campbell addresses this question and says "That the radiation from the Sun (and from many sequence stars) should be concentrated into a minuscule band of the electromagnetic spectrum which provides precisely the radiation required to maintain life on earth is very remarkable." According to Campbell, this situation is "staggering".66
Let us now examine these "staggering features of light" more closely.
From Ultraviolet to Infrared
We said that there was a range of 1:1025 in the sizes of the longest and shortest electromagnetic wavelengths. We also said that the amount of energy that was carried depended upon the wavelength: shorter wavelengths pack more energy than longer ones. Another difference has to do with how radiation at different wavelengths interacts with matter.
The shortest forms of radiation are called (in increasing order of wavelength) "gamma rays", "X-rays", and "ultraviolet light". They have the ability to split atoms because they are so highly energized. All three can cause molecules–especially organic molecules–to break up. In effect, they tear matter apart at the atomic or molecular level.
Radiation with wavelengths longer than visible light begins at infrared and extends up to radio waves. Its impact upon matter is less serious because the energy it conveys is not as great.
The "impact upon matter" that we spoke of has to do with chemical reactions. A significant number of chemical reactions can take place only if energy is added to the reaction. The energy required to start a chemical reaction is called its "energy threshold". If the energy is less than this threshold, the reaction will never start and if it is more, it is of no good: in either case, the energy will have been wasted.
Nearly all of the Sun's radiation is restricted to a narrow band of wavelengths ranging from 0.3 to 1.50 microns. This band encompasses near ultraviolet, visible, and infrared light.
In the whole electromagnetic spectrum, there is just one little band that has the energy to cross this threshold exactly. Its wavelengths range between 0.70 microns and 0.40 microns and if you'd like to see it, you can: just raise your head and look around–it's called "visible light". This radiation causes chemical reactions to take place in your eyes and that is why you are able to see.
"The radiation known as "visible light" makes up 41% of sunlight even though it occupies less than 1/1025 of the whole electromagnetic spectrum. In his famous article "Life and Light", which appeared in Scientific American, the renowned physicist George Wald considered this matter and wrote "the radiation that is useful in prompting orderly chemical reactions comprises the great bulk of that of our sun."67 That the Sun should radiate light so exactly right for life is indeed an important example of Creation.
Is the rest of the light the Sun radiates good for anything?
When we look at this part of the light we see that a large part of solar radiation falling outside the range of visible light is in the section of the spectrum called "near infrared". This begins where visible light ends and again occupies a very small part of the total spectrum–less than 1/1025.68
Is infrared light good for anything? Yes, but this time it's no use to look around because you can't see it with the naked eye. However you can easily feel it: the warmth you feel on your face when you look up on a bright sunny summer or spring day is caused by infrared radiation coming from the Sun.
The Sun's infrared radiation is what carries the thermal energy that keeps Earth warm. It too is as essential for life as visible light is. And the fascinating thing is that our Sun was apparently created just to serve for these two purposes, because these two kinds of light make up the greatest part of sunlight.
And the third part of sunlight? Is that of any benefit?
You can bet on it. This is "near ultraviolet light" and it makes up the smallest fraction of sunlight. Like all ultraviolet light, it is highly energized and it can cause damage to living cells. The Sun's ultraviolet light however is the "least harmful" kind since it is closest to visible light. Although overexposure to solar ultraviolet light has been shown to cause cancer and cellular mutations, it has one vital benefit: the ultraviolet light concentrated in such a miniscule band69 is needed for the synthesis of vitamin D in humans and other vertebrates. (Vitamin D is necessary for the formation and nourishment of bone: without it, bones become soft or malformed, a disease called rickets that occurs in people deprived of sunlight for great lengths of time.)
In other words, all the radiation emitted by the Sun is essential to life: none of it is wasted. The amazing thing is that all this radiation is limited to a 1/1025 interval of the whole electromagnetic spectrum yet it is sufficient to keep us warm, see, and allow all the chemical reactions necessary for life to take place.
Even if all the other conditions necessary for life and mentioned elsewhere in this book existed, if the light radiated by the Sun fell into any other part of the electromagnetic spectrum, there could be no life on Earth. It is certainly impossible to explain the fulfillment of this condition having a probability of 1 in 1025 with a logic of coincidence.
And if all this were not enough, light does something else: it keeps us fed, too!
Photosynthesis and Light
Photosynthesis is a chemical process whose name almost everyone who's ever gone to school will be familiar with. Most people however fail to realize how vitally important this process is for life on Earth or what a mystery its workings are.
First let's brush off our high-school chemistry and take a look at the formula for the photosynthesis reaction:
Translated into words this means: Water and carbon dioxide and sunlight produces glucose and oxygen.
To be more exact what is happening in this chemical reaction is that six molecules of water (H2O) combine with six molecules of carbon dioxide (CO2) in a reaction that is energized by sunlight. When the reaction is complete, the result is a single molecule of glucose (C6H12O6), a simple sugar that is a fundamental element of nutrition, and six molecules of gaseous oxygen (O2). The source of all nutriments on our planet, glucose contains a great deal of energy.
Simple though this reaction may look, it is in fact enormously complex. There is only one place where it occurs: in plants. The plants of this world produce the basic food for all living things. Every other living thing is ultimately nourished in one way or another by glucose. Herbivorous animals eat the plants themselves and carnivorous animals eat plants and/or other animals. Human beings are no exception: our energy is derived from the food we eat and comes from the same source. Every apple, potato, chocolate, or steak or anything else you eat is supplying you with energy that came from the Sun.
But photosynthesis is important for another reason. The reaction has two products: in addition to glucose, it also releases six molecules of oxygen. What's happening here is that plants are continuously cleaning up an atmosphere that is constantly being "polluted" by air-breathing creatures–human beings and animals, whose energy is derived from combustion in oxygen, a reaction that produces carbon dioxide. If plants didn't release oxygen, the oxygen-breathers would eventually use up all the free oxygen in the atmosphere and that would be the end of them. Instead, the oxygen in the atmosphere is constantly being replenished by plants.
For hundreds of millions of years, plants have been busy doing something no laboratory has ever been able to duplicate: Using sunlight, the produce food. A crucial condition for this extraordinary transformation however is that the light that the plants receive must be precisely right for photosynthesis to take place.
Without photosynthesis, plant life could not exist; and without plant life, there would be no animal or human life. This marvelous chemical reaction, which has never been duplicated in any laboratory, is taking place deep in the grass you step on and in trees. It once occurred in the vegetables on your dinner plate. It is one of the fundamental processes of life.
When we study photosynthesis, we can't help but observe that there is a perfect balance between plant photosynthesis and the energy consumption of oxygen-breathers. Plants supply glucose and oxygen. Oxygen-breathers burn the glucose in the oxygen in their cells to get energy and they release carbon dioxide and water (in effect, they're reversing the photosynthesis reaction) that the plants use to make more glucose and oxygen. And so it goes on, a continuous cycle that is called the "carbon cycle" and it is powered by the energy of the Sun.
In order to see how perfectly-created this cycle truly is, let us focus our attention on just one of its elements for the moment: the sunlight.
In the first part of this chapter we looked at sunlight and found that its radiation components were specially tailored to allow life on Earth. Could sunlight also be deliberately tailored for photosynthesis as well? Or are plants flexible enough so that they can perform the reaction no matter which kind of light reaches them?
The American astronomer George Greenstein discusses this in The Symbiotic Universe:
THE FITNESS OF SUNLIGHT AND CHLOROPHYLL
In the last chapter we drew attention to the error inherent in the idea of the adaptability of life. Some evolutionists hold that "if conditions had been different, life would have evolved to be perfectly in harmony with them as well". Thinking superficially about photosynthesis and plants, one could come to a similar conclusion: "If sunlight were different, plants would have just evolved according to that." But this is in fact impossible. Although he's an evolutionist himself, George Greenstein admits this:
What Greenstein is saying briefly is this: No plant can only perform photosynthesis except within a very narrow range of light wavelengths. And that range corresponds exactly to the light given out by the Sun.
The harmony between stellar and molecular physics that Greenstein refers to is a harmony too extraordinary ever to be explained by chance. There was only one chance in 1025 of the Sun's providing just the right kind of light necessary for us and that there should be molecules in our world that are capable of using that light. This perfect harmony is unquestionably proof of Creation.
In other words, there is a single Creator, the Ruler of starlight and of the molecules of plants Who has created all these things in harmony with one other, exactly as is revealed in the Qur'an:
He is Allah–the Creator, the Maker, the Giver of Form. To Him belong the Most Beautiful Names. Everything in the heavens and earth glorifies Him. He is the Almighty, the All Wise. (Surat al-Hashr: 24)
The Light of Your Eyes
We have seen how the light coming to us from the Sun consists of just three narrow bands of the electromagnetic spectrum:
The existence of a range of "visible light" is as important for the support of biological vision as it is for photosynthesis. The reason is that it is impossible for a biological eye to see any band of the spectrum outside that of visible light and a very small section of near infrared.
To explain why this should be so, we first need to understand how vision takes place. It begins with particles of light called "photons" passing through the pupil of eye and falling onto the surface of the retina located at the back of the eye. The retina contains cells that are light-sensitive. They are so sensitive that each can recognize when even a single photon strikes it. The photon's energy activates a complex molecule called "rhodopsine", large quantities of which are contained in these cells. The rhodopsine in turn activates other cells and those activate still others in turn.72 Eventually an electrical current is generated and this is carried to the brain by the optic nerves.
The first requirement for this system to work is that the retina cell must be able to recognize when a photon strikes it. For that to happen, the photon must carry an exact amount of energy: if it is too much or too less, it won't activate the formation of rhodopsine. Changing the size of the eye makes no difference: the crucial thing is the harmony between the size of the cell and the wavelengths of the photons coming in.
Our Sun has a surface temperature of about 6,000°C. If this temperature were even slightly more or less, the resulting sunlight would be incapable of supporting life.
Making an organic eye that could see other ranges of the electromagnetic spectrum turns out to be impossible in a world dominated by carbon-based life. In Nature's Destiny, Michael Denton explains this subject in detail and confirms that an organic eye can only see within the range of visible light. While other models of eyes that could, in theory, be produced, none of them would be able to see different ranges of the spectrum. Denton tells us why:
UV, X-ray, and gamma rays are too energetic and are highly destructive, while infrared and radio waves are too weak to be detected because they impart so little energy interacting with matter... And so it would appear that for several different reasons, the visual region of the electromagnetic spectrum is the one region supremely fit for biological vision and particularly for the high-resolution vertebrate camera eye of a design and dimension very close to that of the human eye.73
Pausing to think about everything that has been said so far, we come to this conclusion: The Sun radiates energy within a narrow band (a band so narrow that it corresponds to just 1/1025 of the whole electromagnetic spectrum) that has been carefully chosen. So finely adjusted is this band that it keeps the world warm, supports the biological functions of complex life-forms, enables photosynthesis, and allows the creatures of this world to see.
The Right Star, the Right Planet