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Light

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Light is very important to the universe and our existence. Sunlight is the food source of plants and plankton, which is the basis of the food chain on earth. The light from the sun also heats the planet and makes it habitable. Light is also necessary for vision. However, despite its importance, scientists today still do not fully understand it. Also, the limited speed at which light can travel poses many troubling questions for both Creationism and the Theory of Evolution.

What Is Light?

Visible light lies within a small area of the electromagnetic spectrum

Light refers to the visible light portion within the electromagnetic spectrum. This visible light travels through electromagnetic fields in the form of energy packets called photons. A photon is an elementary particle that travels both as an electromagnetic wave and as a particle, and has properties of both. For example, light can be reflected and refracted just like waves, but can also strike and affect other particles such as electrons. This property of light is called wave-particle duality.[1] The photons travel as waves through electromagnetic fields. These waves have amplitude, which determines the brightness, and frequency, which determines the color. As these waves hit our eyes, they are interpreted as different colors.[2]

Light can either be produced through incandescence or luminescence. Incandescent light is given off when electromagnetic energy is released from a heated atom. Fires, stars, and light-bulbs give off incandescent light. The color of the light given off is dependent upon the amount of energy that the atoms have. Lower energy atoms give off light in the infrared spectrum, while higher energy atoms will give off light more toward the blue end of the spectrum. Luminescent light is given off by excited electrons. When electrons are energized, they jump up to another electron level, then jump back down to their original level, and this gives off electromagnetic energy. Most chemical reactions, computer monitors, and neon lights give off luminescent light.[2]

Visible light is the light that we see with our eyes. They are electromagnetic waves that are seen as a rainbow. Light is broken up when going through a prism, then each color goes in a different direction depending on the wavelength. Red has the longest wavelength and violet has the shortest. [3] The frequencies of visible light range from 4-7.5 X 1014Hz. Although there are several different colors of visible light, there are many kinds of light that cannot be seen. The best examples of these would be infrared, ultraviolet, X-rays, and gamma rays.[4]

History of Light

Sir Isaac Newton was one of the first people to propose a theory of what light is. He claimed that light was a constant stream of extremely small particles. This theory was accepted for a long time. Then, scientists began to notice properties of light that could not be explained by Newton's theory. For instance, when light was passed through a narrow slit, the beam of light exhibited interference. This led many scientists to believe that light was a wave, not a stream of particles. When work done by James Maxwell proved that electric and magnetic waves travel in interlocking, oscillating waves, the wave-theory of light became universally accepted. About twenty years later, it was noticed that when light came into contact with metal, streams of electrons were given off, something that does not agree with Maxwell's electromagnetic wave theory. Albert Einstein, a German physicist, explained the phenomenon by proposing that light was not in fact a wave, but a travelling packet of energy called a photon. This theory won him the Nobel Prize in 1913. Later, Prince Louis deBroglie examined Einstein's photon theory and the wave theory formed by Max Plank and decided that both could be right. He theorized that light could actually be a photon travelling as a wave, thereby having the properties of both. This was the birth of the wave-particle duality theory.[5]

Properties Of Light

Light has many interesting properties that still fascinate physicists today.

Reflection

When light strikes a reflective surface, it will bounce off it at a different direction. The angle of the reflected beam is equal to the angle of the beam hitting the reflective surface, or, more simply stated by the Law of Reflection, “the angle of incidence is equal to the angle of reflection”. There are two types of reflection: specular and diffused. Specular reflection is reflection off of a flat surface, such as a mirror. This produces a flat, undisturbed picture. Diffused reflection is reflection coming off of a rough or bumpy surface, producing a muddled and unclear picture. [6]

Refraction

Whenever light travels through a boundary between two mediums, the light bends. This is because of the density differences between the two mediums. Since one of the mediums is more dense than the other, the speed of light within the denser medium is slower, and this causes the bending. This can be seen when items underwater such as fish appear larger while under the water than they are out of the water.[7] Normally, whenever light is refracted through a medium, some of the light reflects off of the medium instead of entering it. If light enters the medium at a certain angle, however, the light will refract to ninety degrees. The angle that the entering light needs to be in order to refract to ninety degrees within a certain medium is called the critical angle. If the light enters a medium at an angle greater than the critical angle, all of the light will reflect back. This is called total internal reflection. This is used in fiber optics to transmit data over long distances using light waves without losing any of the data.[8]

A rainbow is an example of light dispersion

Dispersion

The white light that we normally see is not really the color white. In actuality, it is a combination of all colors that makes the light appear to be white. If white light is shone through a prism or similar object, then the white light will disperse and separate out into all of the colors. A rainbow is an example of dispersion. After a rainstorm, many tiny water particles hang suspended in the air, and as white light hits the water droplets, they act like a prism, causing the white light to separate out into all of the colors.[7]

Interference

Light waves are able to interact with each other while travelling through the same medium. When two light waves come into contact with each other, they will either be amplified or cancelled out. If the two waves that encounter each other are in phase with each other, then constructive interference will occur. In this case, the amplitudes of the two beams will combine and create one amplified beam. If the two waves are not in phase with each other, then destructive interference will occur. In this case, the two waves will cancel each other out. After the two waves have passed each other, however, they will go back to their original state with absolutely no change.[9]

Diffraction

Light does not always travel in a straight line. When light encounters the corner of an object, the waves are altered, take on a new shape, and go in a new direction. This produces the fuzzy edge that most shadows have. This is also shown when light passes through a narrow slit. When light is shone through a slit, the waves interfere with each other, and instead of coming out as one beam, it comes out as many different beams of varying brightness.[10]

Speed of Light

Light travels extremely fast, at 299,792,458 meters per second or 186,282 miles per second in a vacuum.

Problems with Starlight

We should not be able to see galaxies millions of light years away, but we can.

Even though light travels at very fast speeds, outer space is also very large. The distances between objects in space are so vast that they are measured in light years, which is the distance light can travel in a year, roughly six trillion miles. For example, if an object is ten light years away, then it would take the light from that object ten years to reach us. This consistency in the speed of light presents an interesting problem for both Creationism and the Big Bang Theory.[11]

Starlight Travel Time Problem

According to the Biblical model of Creation, the universe is only about 6,000 years old. If this is true, than we should only be able to see stellar objects that are closer than 6,000 light years to us. The problem is this is not true. In fact, we can see galaxies that are billions of light years away, even though there should not have been enough time for the light from those galaxies to reach us. Creationist scientists have been trying to find an explanation to the starlight travel time problem for years, and although there is no definite answer so far, many different theories have been presented.[11]

Solutions to the Starlight Travel Time Problem

Many solution shave been presented to explain this problem. Some people have argued that in the past, light traveled at a much faster rate than it does now. If this were true, then the light would have easily been able to reach earth in a few thousand years. One article by B. Setterfield argues that light could have been extremely fast at the time of creation and decreased exponentially to the speed that it is today. By examining the predicted speeds of light in past years, he drew a graph that he used to predict the speed of light in past years. The results showed a time for creation at about 4,040 B.C., with light traveling at 1.5 x 1017 kilometers a second, about 5 x 1011 faster than the current speed. According to the theory, the speed of light then decreased exponentially from this point, until it reached the speed that it is today. This model explains the starlight time travel problem, as well as problems found with quasars. There are many other similar theories, and although none have been proven yet, this general theory appears to be a plausible explanation for the starlight travel time problem.[12]

Another possible solution to the starlight travel time problem involves the relativity of time and white holes. This theory, often called Humphrey's White-hole Cosmology, argues that during the creation week, all matter came out of a white hole, which is a theoretical object with an extremely high mass that emits all kinds of matter. The large mass of the white hole would have an extremely powerful gravitational field, powerful enough to affect the flow of time. The earth, supposedly being near the white hole, would be affected by the warping of time, so time would flow much slower on earth than it would in the rest of the cosmos. Thus, while six days of creation passed on earth, millions or billions of years could have passed in the rest of the universe, giving plenty of time for the light from distant galaxies to reach us. This theory has many problems, and has been revised many times. While this particular theory is not generally accepted as fact, the fact that time was warped during the creation week is still considered plausible, and is still usually considered a possible solution to the starlight travel time problem.[11]

Another possible and much more simpler solution to the starlight travel time problem is that God is all powerful and made all light visible at all points in the universe at creation with his infinite power. While this may seem like an obvious and easy solution to the problem, it itself has some problems. We can see supernovas occurring millions of light years away. The problem is, those supernovas must have happened millions of years ago for the light to reach us at its constant travelling speed, which is way before Creation, so the light would have come from an event that never actually occurred. Many Christians have difficulty accepting the fact that God would intentionally deceive us by creating light from events that never happened.[11]

The Horizon Problem

While many evolutionists point out the starlight travel time problem, they forget that the Big Bang Theory has its own problem with starlight travel time. According to the Big Bang Theory, the early universe was extremely varied in temperature throughout. However, today we see an almost uniform temperature throughout the entire universe. The problem is, the different areas of the universe would have had to exchange light in order to become equal in temperature. Even with the billions of years allotted for the Theory of Evolution, there has not been enough time for the different areas of the universe to exchange light. This problem is called the Horizon Problem. Evolutionists still struggle with solving this problem, and very few likely solutions have been proposed.[13]

Solutions for the Horizon Problem

The current and most accepted theory to solve the Horizon Problem is called Inflation. Basically, the theory argues that at one point, the universe was condensed and all points in it were in very close contact with one another, allowing them to share light. Then, the universe inflated greatly, so the universe was uniform before it expanded. This theory is far from being proved, and there are no models that propose a likely way for the universe to suddenly inflate. There are many other problems associated with Inflation, so the Horizon Problem is still highly controversial.[13]

Many other theories to solve the Horizon Problem, mainly dealing with time variance due to gravity, an increased speed of light in the past, and the possibility that light travels through alternate dimensions.[13]

References

  1. What is a Photon? Andrew Jones, About.com, Accessed April 10, 2011
  2. 2.0 2.1 What Is Light? Think Quest, Accessed April 10, 2011
  3. Netting, Ruth. visible light waves Visible light waves. Web. Date of access March 31, 2014.
  4. Nave, R. Infrared Electromagnetic spectrum. Web. Date of access March 31, 2014.
  5. Light Background ThinkQuest, Accessed April 21, 2011
  6. Reflection Think Quest, Accessed April 10, 2011
  7. 7.0 7.1 Properties Of Light Physics Planet, Accessed April 10, 2011
  8. Total Internal Reflection Hyper Physics, Accessed April 10, 2011
  9. Interference Think Quest, accessed April 10, 2011
  10. Diffraction Think Quest, Accessed April 10, 2011
  11. 11.0 11.1 11.2 11.3 A New Cosmology: Solution to the Starlight Travel Time Problem John G. Hartnett, Creation Ministries International, August 2003]
  12. The Velocity of Light and the Age of the Universe B. Setterfield, Answers in Genesis, March 1, 1981
  13. 13.0 13.1 13.2 Light-travel Time: A Problem for the Big Bang Robert Newton, Answers in Genesis, September 2003