A particle, should be either at rest or at speed v without extra force apply on it. If it is moving, it moves along straight line. If it hits something, it may pass through/halfway, reflect or deflect. It will lose momentum/speed anyways. Does any light or EM wave ever slowdown? If light is particle, how a particle hits mirror and reflect back? What bounces it back? The electron? The nucleus? The empty space within silver atoms?
''Does any light or EM wave ever slowdown?'' Light is of the EM radiation/EM wave. Yes light slows down in a medium such as a cloud. ''The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly 299792458 metres per second, as the length of the metre is defined from this constant and the international standard for time.[1] According to special relativity, c is the maximum speed at which all matter and information in the universe can travel. It is the speed at which all massless particles and changes of the associated fields (including electromagnetic radiation such as light andgravitational waves) travel in vacuum. Such particles and waves travel at c regardless of the motion of the source or the inertial frame of reference of the observer. In the theory of relativity, c interrelates space and time, and also appears in the famous equation of mass–energy equivalence E = mc2.[2] The speed at which light propagates through transparent materials, such as glass or air, is less than c. The ratio between c and the speed v at which light travels in a material is called the refractive index n of the material (n = c / v). For example, for visible light the refractive index of glass is typically around 1.5, meaning that light in glass travels at c / 1.5 ≈ 200000 km/s; the refractive index of air for visible light is about 1.0003, so the speed of light in air is about 299700 km/s or 90 km/s slower than c.'' http://en.wikipedia.org/wiki/Speed_of_light ''If light is particle, how a particle hits mirror and reflect back? What bounces it back?'' ''Reflection is the change in direction of a wavefront at an interface between two different media so that the wave front returns into the medium from which it originated. Common examples include the reflection of light,'' Your question answers it for you, some Photons are absorbed and other Photons are reflected by the mirror.
How a particle slowed down from air and back to c in vacuum? How a particle absorbed or reflected by mirror? What's the mechanism? Can you show me any link to the answers?
Light passes water slowed down, passed water speed back to c. If it is particle, what accelerates it? You may say energy level changed, how? Thanks!
When light interacts with matter, the atoms in the matter become ''excited'', then because of thermodynamics, the Kinetic ''excitement'' expands the matter by the electron shell expanding, (On a micro scale of cause), then because the object does not want to lose form/shape, the object has to lose energy to surrounding environment, so emits energy in the form of radiation, often infra red radiation, invisible to sight but visible to devices.
Good question, Ok , I think I understand what you are asking now, consider particle, and then consider particles, Natural Light is particles. I am not 100% sure on the answer to this, and maybe someone else later can answer this 100% later. My own opinion, but please do not take this for being facts, is that when light slows down in a medium such as a cloud, the propagation of the light in the cloud and the continued flow of Photons from the incident ray build up Kinetic energy in the propagated light in the cloud, then when the Photons leave the cloud, it is like being shot from a Gun to reach the Photons maximum limit of c. P.s - Or it does not speed back up.
Excited is basically an increase in activity by adding energy/heat to the matters atoms, ''Excitation is an elevation in energy level above an arbitrary baseline energy state. In physics there is a specific technical definition for energy level which is often associated with an atom being excited to an excited state. In quantum mechanics an excited state of a system (such as an atom, molecule or nucleus) is any quantum state of the system that has a higher energy than the ground state (that is, more energy than the absolute minimum). The temperatureof a group of particles is indicative of the level of excitation (with the notable exception of systems that exhibit Negative temperature).'' http://en.wikipedia.org/wiki/Excited_state The Nucleus gains which excites the electrons.
Energy, heat, energy level are hard to understand by words. Let's see how light is produced? Without atom/matter, no light will shine. So let's look the atoms structure first. QM atom structure suggests that atoms are like different sized ping pong balls. Negative electron orbital shell, empty space and center positive nucleus. 3 questions, how electron not stick with nucleus? Why atoms deep in Planet center not crash under high pressure? How 2 O atoms form into 1 O2 since the shell of the 2 ping pong balls are all negative charged? QM says electrons excited and emit photon by some energy level exchanges, words are just words. What's the action?
Science knows light is produced by use of devices to see the light that is emitted, light that is below our visual range to see. ''how electron not stick with nucleus?'' You have that question in other thread. I am unable to answer that because I have also asked and thought about that. ''Why atoms deep in Planet center not crash under high pressure?'' High pressure that builds up energy that is released by energy emitted into the mantle etc. The pressure is no where near high enough to crush atoms, the force of a Neutron star is the sort of force and gravity required. http://en.wikipedia.org/wiki/Neutron_star
Putting it as simply as possible, light upon entering a medium other then a vacuum, has a longer distance to travel...It is absorbed re-emitted but always moving at "c" as it does in a vacuum. Or to put it another way, the simplest explanation is that light always travels at "c " But in a material other then a vacuum, it will hit atoms and is then absorbed and re-emitted, which takes a small amount of time. The more atoms, the the slower the effective average speed. The denser the material, the more atoms there are in the way. Some of our purists may not like that description, but I believe it paints a reasonable picture as to what is happening. Please Register or Log in to view the hidden image!
Words are just words?? That's a strange thing to say. Words convey a meaning. If you don't know what a word means, then check a dictionary or ask. If I say to you God is a silly myth. Do you understand what I'm saying? Now with science, it operates via the scientific method and peer review. Not perfect, but better then anything else we have. Science formulates theories, based on observational and experimental evidence....science theories change over time, and the further we see. Some theories like our theory of light are certain and taken for granted....just as Newton's theory of gravity, and the "fact" that if we jump up in the air, we will come back down. Other theories that are so well supported by the mountains of evidence that they are near certain, are SR and GR, along with Evolution and Abiogenesis.
jcc, there are at least a few different "theories" on Light...the following link will get you started with a few of these "theories"...if you are interested. http://www.angelfire.com/sc3/light/theories.htm
What a horribly formatted web page. I had no idea Angelfire even still existed, I thought it went the way of Geocities back in the late 1990's. Here's a copy/paste for people who care. However, I recommend starting at the Wikipedia page and go on from there. http://en.wikipedia.org/wiki/Light
The point is if you check out jcc's posts and past threads, like other alternative hypothesis pushers, it appears he does not want a mainstream acceptable correct answer. We'll seen soon enough whether he tries pushing some other invalid concept according to his beliefs. One of his threads has already has been removed from the science section.
