Why exactly does this work as a solution? Also, I really like your approach. :smallbiggrin:
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Well, when two are perpendicular, they filter out all the light. But when you put two in the middle, twisted a bit, they reorient some of the light the first one polarises, so not all of that is blocked by the one that's perpendicular to the first. It's still not like looking through a clear sheet, but it's better than looking through two perpendicular polarising sheets.
Something like that.
Often when you look at large rivers, the surface seems to have to different types of "textures". Some parts have few waves and reflect the surroundings, while others are more frizzled and don't produce discernable mirror images.
Why is that? What's happening with the water?
Disruption of flow from underwater rocks and flora?
Could have something to do with superposition--this basically says that when you have two waves affecting the same point, the result is what you get when you add the waves together. So, if one wave is at negative amplitude and the other is positive, they'll cancel each other out. Since you'll have a lot of waves crossing and re-crossing the water, the interaction of them all is going to produce some complex effects.
What is a photon, and how is related to the electromagnetic spectrum?
I understand that it's supposed to be the substance of light, but that's only a vague description.
How is it vague? If I understand properly (and there's a fair chance I might not) light is fundamental. It isn't made up of anything, the same way electrons aren't made up of anything. A photon is a unit of light. You can't have less light than one photon and any quantity of light must be a whole number of photons. Also, things get wacky with quantum mechanics, I don't really understand it well enough to explain, but light can be described as a wave despite being made up of photons. In fact a single photon is somehow a wave. Kind of.
As for the electromagnetic spectrum, that is more complicated. Light is electromagnetic radiation. Which is the same as saying that photons are electromagnetic radiation. The electromagnetic spectrum is simply the range of frequencies electromagnetic radiation can take, and we perceive different frequencies as being different colors, although we can only see a limited range.
I think in current physics, electrons are considered to be waves as well and not particles. The particle model works well enough for chemistry, but apparently has not much to do with what electrons really are.
I'm pretty sure the situation is that electrons can act as both particles and waves depending on the circumstances. For example, they will diffract when fired through a diffraction grating, but they can also collide with atomic particles and be affected by magnetic fields, neither of which a pure wave would do.
My research leaves me to believe that this is a matter not entirely decided as of yet. The most certain thing is that they are not waves or particles in the standard sense. The most common interpretation, if I understand it correctly, is that electrons (and photons) are neither particles nor waves but can act as either depending on the circumstances. Another view is that they never act as either particles or waves, but as something inbetween that in the past we have merely succeeded as modelling as a particle or wave in different circumstances. A minority opinion I've heard, and I can't say whether it should be taken seriously or not, is that electrons and photons are in fact both just waves, but weird quantized waves that can be mistaken for particles.
My understanding of the subject is that photons and electrons are confusing things of indeterminate nature that act similarly to both waves and particles but can probably do other things too, we just haven't discovered those other things yet.
It's very much decided. They're quantum objects (as is everything), which means that they're neither, but in different contexts they may act similar to particles or waves.
@noparlpf: Make no mistake. Just because we can't liken a photon or electron's behaviour to the way everyday, macroscopic stuff behaves, that doesn't mean we understand how they act to a freightening degree of accuracy. As for 'what they really are' it seems that such a question literally makes no sense. It's much like asking "how tall is the color green?"
A photon is a boson (more exactly a gauge boson, but that is probably too much for you), a packet (quanta) of energy and momentum used to mediate electromagnetic interactions, characterized by a spin number of one (important for its statistically properties) and no mass. Basically what this means is that in electromagnetic interactions energy is transferred into small packets of energy, that is, light is made of a large number of discrete units. That's what «particle» means in this sense.
Strangely enough, despite being particles, their description requires the use of wave properties, with frequencies and wavelengths. The energy (E) of the photon defines a quantity called frequency (v) , by the simple relation E = hv, where h is the so called Planck constant. This frequency, or the corresponding wavelength (l = c/v, c being the speed of light) is what we associate with color. The electromagnetic spectrum is nothing more than the range of wavelengths of the photons.
I'm not a physicist, so I'm just reporting what I've read, but what I've read is written by physicists so you'll forgive me if I'm not yet convinced of what you say. To be clear, I don't think anyone except the one wave guy strictly disagrees with you. But there are at least two ways of interpreting what you said. In what I understand to be the standard model wave-particles act exactly like waves in some circumstances and exactly like particles in others, but never like both at the same time. The other interpretation has them always acting like some sort of wave-particle which we only approximate as waves and particles in different circumstances. I don't think the math changes either way, this is just interpretation.
I'm fairly certain that you don't need to use wave properties to describe a photon, as the momentum of the photon will uniquely describe it as well.
But it's just easier to use frequency and wavelength, because light behaves more like a wave at macroscopic levels than it does a particle.
Interesting point, but I thought it was the other way around - it's only when you break it down to individual particles that the wave-particle duality becomes obvious and thus necessary. The double-slit experiment, for example; it can be explained away as particles taking different routes and interfering with each other - in other words, a large group of particles can act like a wave, just like a large group of water molecules can - but when you only let a single particle through, you get the same interference pattern, which can only be explained by the wave-like nature of the particle itself (or possibly alternate universes or whatever, but never mind that).
Also, on an unrelated note, the forums just bugged out and replaced the little green arrow with an emoticon of the ancient black dragon. But when I refreshed, it went back to normal. Did my attempt to observe it change the outcome? :smallamused:
Well yeah, that's what I meant. At macroscopic levels you're dealing with something that by all intents and purposes is a wave. Okay, it's a lot of particles that look like a wave, but it's easier to talk about it's frequency and wavelength in that context.
I have to say that just the concept of a wave surpasses my comprehension. I understand a wave of liquid or a wave of pressure, or even a sine wave as a mathmatical function.
But a wave of electromagnetism? The wind tastes awfully blue today.
It's kinda simple once you understand it. The key to it all is that a moving electric field creates a magnetic field, and a moving magnetic field creates an electric field. So you start with an oscillating electric field. The creates a magnetic field oscillating perpendicularly, and you can see where that leads. What you get is mutually perpendicular oscillating fields propagating each other in the third perpendicular direction.
A.K.A, Electromagnetic Radiation.
Is Earth just spiralling the drain? By which I mean we are already losing .0...1 of a second (I'm not sure how many zeros) each day. One day, after all of Eath's systems die down, when all currents, spheres and rotations stop (which it will) will Earth just plummet into the sun?
Well, the sun also loses mass while Earth loses velocity, this may results in both canceling each other out, or even cause the earth to move in increasingly larger circles. The moon is making increasingly larger circles around the earth.
However, I've read in several places that the earth will be crushed by gravity as the Sun grows larger (and at the same time less denser), so the effect of gravity on earth appears to be increasing. Which would mean yes, eventually it would fall in.
You mean it's a series of alternating layers of magnetic and electronic fields?
Er, what? The Sun may very well get larger as it gets older, but it won't get any more massive--where would the extra mass come from? Thus the gravitational field at Earth's distance would be exactly the same. What may well happen once the Sun becomes a red giant is that the star will be so large that the Earth will be orbiting through its outer layers, and even though those layers will be so tenuous they'll be a pretty good approximation of a vacuum, there'll still be enough drag to slow the Earth in its orbit and cause it to fall deeper into the Sun, eventually to be consumed.
As for the Earth's orbit slowing down, yes, it is, but this is because the Earth is actually moving further from the Sun. The rate at which this is happening is absolutely tiny, though, no need to worry about it for a good few thousand million years!
Just because green light has a wavelength of 550 nm doesn't mean the color green itself is that tall.