I have been considering rewriting the following essay on the nature of light, but have decided instead to add a postscript at the front of the article so readers don’t have to read the entire essay to discover the mystery.
Physicists have long debated whether light IS a wave or IS particle. Those who believe there are light waves have had trouble explaining what is “waving”. The answer that electrons are waving should have been obvious, but wasn’t considered because of a false perception of the space between planets and stars. We think of space as a vacuum, but it is actually only a relative vacuum. Space contains dust from events such as exploding stars and collisions of asteroids with each other and with planets; light mass gases like helium, hydrogen and water vapor; and even some free electrons.
Electrons transfer electrical energy in the form of electricity so it wouldn’t be surprising if they transferred electrical energy in the form of electro-magnetic radiation. Electron waves would explain why light causes heating in some materials, particularly solids, and not in other matter particularly gases and some liquids. The passage of radiation through a substance would cause heating in the same basic way as the passage of electricity. Substances heat up based on their resistance to the passage of the energy. Electrons in atoms in a gas or liquid state may be freer to pass along radiant energy than electrons that are part of a rigid matrix in a solid. The receipt of radiant energy by electrons in a solid may cause the atoms they are a part of to move [i.e., become hotter].
The mystery of light helped cause an interest in studying physics a long time ago. I have retained that interest, but am no longer ambitious enough to try to prove a theory that light involves electron waves. I’ll leave that task up to those who are younger and have more energy to pursue the subject.
|19th Century beliefs about the nature of light continue to hamper a study of light.
Early 19th Century physics was characterized by support for various theories that were subsequently disproved such as the theory that atoms were the smallest particles of matter and an atom of one element could not be converted to another element. J.J. Thomson disproved the first theory with his discovery of the electron in 1897. Physicists also discovered that the processes of nuclear fission and nuclear fusion could change an atom of one element to an atom of another element.
Unfortunately the 19th Century debate suggesting that light must BE a particle or BE a wave survives. The confusion comes in part from the fact that in some situations light acts like a particle and in other situations acts like a wave.
The standing joke when I studied light in the 60’s was about the university that taught that light was a wave on Monday, Wednesday and Friday; and taught that light was a particle on Tuesday, Thursday and Saturday. My professor took a different approach. He taught light as a wave for half a semester and light as a particle the other half.
This false dichotomy continues to hamper an understanding of light (i.e., electromagnetic radiation). Some physicists have tried to get around the dichotomy by suggesting that light consists of particles that may actually be something called wavicles.
This idea implies a misunderstanding of what a wave is. A wave involves particles forming temporary sets which momentarily function in unison. Air molecules normally move around like ping pong balls in a bingo machine. However, when a sound wave passes through air the separate molecules temporarily function as if they were entangled with each other as they pass along the sound energy to adjacent air molecules. Once the wave has passed the air molecules return to moving independently.
Physicists ignore the fact that if light is a form of energy it cannot be a particle or be a wave although particles or waves might transfer it from one location to another like particles and waves transfer kinetic energy from one location to another. Particles are ultimately matter, not energy. Waves involve the movement of matter. Particles and waves transfer energy, but they are not energy.
If I throw a baseball the kinetic energy produced by the movement of my arm is transferred to the baseball which then transfers that kinetic energy to whatever it hits, such as a bat, a glove or perhaps a window. An underwater earthquake may transfer its kinetic energy to a tsunami wave which may then transfer that energy to objects on a shore a thousand miles away.
Waves transfer kinetic energy much more effectively than particles. The energy used to move a guitar string wouldn’t propel a particle very far. However, that movement produces a wave which can travel a hundred feet or more and reach anyone in an auditorium. Such kinetic energy waves are commonly called “sound waves” because they produce a physical sensation in the human ear which the brain interprets as sound.
Waves can transfer complex sounds from many instruments to the human ear in a manner that allows all the sounds to be heard even though they come from different locations. Light waves would be more likely to be able to transfer light in a variety of colors and intensities in a way that allows the eye to recognize different colors than would individual particles emitted from various locations.
In a classic experiment in quantum physics an individual photon carrying light energy approaching two different gates will go through one gate on some occasions and the second gate on other occasions. If light from Mars were leave the surface as individual photons they would quickly become jumbled together so no details could be seen from Earth. .
Although there are situations in which the transfer of light can be explained as involving particles (photons), many situations such as mirror reflections can only be explained as involving waves. If particles produced a mirror image, objects that aren’t directly in front of the mirror would be reflected as being on the opposite side of the room because the particles would hit the opposite side of the mirror. Some reflective surfaces can produce the effect of light going around a corner.
One of the problems about light as a wave is the need for something to be “waving” as Professor Michael Fowler points out in some of his lectures.
Some type of aether has long been suggested as what might be waving. However, an aether would only be necessary to transfer light waves through space. Physicists have long ignored the possibility that electrons in atoms could transfer light waves just as easily as they transfer electricity.
The transfer of light waves by electrons would explain why the passage of light through some substances causes heating but not other substances. The process would be similar to the process by which the passage of electricity causes heating.
Resistance to the passage of electricity causes heating. Resistance to the passage of electromagnetic radiation could function in the same way.
A possible explanation for the fact that radiation passes through the atmosphere with minimal heating would be that electrons in gas molecules could pass along a wave without resistance because the molecules move independently. Electrons in solids might have less ability to pass along radiation without resistance because the atoms they are part of are held in place in a matrix.
Air molecules can transfer sound waves even though they normally move in a highly disorganized fashion because they can temporarily act as if they were all connected together and acting in unison to transfer complex sounds. Why couldn’t electrons, which can transfer energy through a wire in a highly organized manner, temporarily organize to transfer electromagnetic waves.
Water waves may cause small boats to begin moving back and forth because all of the boat must move at the same time rather than having adjacent molecules move independently as water molecules do. Moving electromagnetic waves through a solid might require entire groups of atoms to move in order for the electrons to transfer the energy as a wave just like an entire boat must move for the kinetic energy in water waves to be transfered to the other side of the boat. The motion of atoms is what physicists define as heat.
The issue of how a light wave could move through space remains. Some type of “aether” would be the most likely explanation.
Physicists claim there must be some type of matter they cannot detect because the matter they can detect seems insufficient to be all the matter of the universe. They usually describe this matter as being “dark”, but transparent matter would be even harder to detect than matter that was dark.
Dark objects don’t emit or reflect light, but they can block light if they pass between the source of the light and the observer. Light can pass through transparent matter without being easily detected.
Transparent matter can be very difficult to detect. In some cases it may be detectable because some frequencies of light don’t pass through, or because the light that passes through isn’t as bright.
Astronomers have noticed that light coming from distant galaxies seems to have been shifted toward the red end of the light spectrum. The greater the distance from earth the greater the red shift. Some have suggested that this red shift indicates the relative velocities of earth and the distant galaxies. However, the shift could also be due to passage through transparent matter such as what has traditionally been called an aether.
A problem with the theory that the shift indicates movement away from earth is that everything seems to be moving away from earth, but the Hubble telescope images indicate that some distant galaxies are moving toward each other, including the movement of our galaxy toward the Andromeda galaxy. Thus it would be more likely that some distant galaxies would show movement toward earth with a shift toward the blue end of the spectrum instead of a uniform red shift. Also the relative motion would vary among galaxies rather than being uniform based on the distance from earth.
The false dichotomy that light must BE a wave or BE a particle continues to hamper an understanding of light in the 21st Century. If light is a form of energy it cannot be a particle or a wave because both involve matter. However, both particles and waves could transfer light energy from location to another just like particles and waves transfer kinetic energy from one location to another.
Original article© Copyright 2011 Reason McLucus (reasonmclucus at Writing.Com). All rights reserved.