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Author Topic:   General Relativity.
RoyLennigan
Inactive Member


Message 46 of 129 (247164)
09-29-2005 2:05 AM
Reply to: Message 44 by madeofstarstuff
09-28-2005 8:36 PM


Re: Light and Energy
but you've got to understand that all these terms do not 'determine' an aspect of the wave. they are all measurements of certain aspects of the wave. the energy of a photon is not dependant upon its frequency, but rather the other way around. the amplitude, and frequency both depend on the energy of a single photon of the wave. the intensity depends on the energy of the entire wave, or source.
about the site specifying that energy of a wave is dependant upon frequency only; well like i said. the energy is not dependant, but the other way around. and for the other part; amplitude is a measure of an aspect of the wave that corresponds to the amount of energy it has. when you turn up the volume on your speakers, you are increasing the amplitude of the sound wave they are producing, but you aren't changing the frequency of the notes being played. it works the same way with light.
the last picture is sort of misleading because it is not in 3D. refer to the link in 1.61803's post after mine, message 42. electric fields and magnetic fields are at perpendicular angles.
photons are grouped together that have the same frequency, amplitude, and wavelength; they all come from the same source, and have the same properties. the measurement that differentiates is intensity. intensity measures the energy per unit volume (volume=space) multiplied by the velocity. so it measures the overall energy of the entire wave, which varies depending on the number of photons. intesity is measured in watts, perhaps you can relate that to something familiar
This message has been edited by RoyLennigan, 09-29-2005 02:08 AM

This message is a reply to:
 Message 44 by madeofstarstuff, posted 09-28-2005 8:36 PM madeofstarstuff has replied

Replies to this message:
 Message 47 by madeofstarstuff, posted 09-29-2005 12:10 PM RoyLennigan has replied

  
madeofstarstuff
Member (Idle past 5929 days)
Posts: 47
Joined: 08-12-2005


Message 47 of 129 (247296)
09-29-2005 12:10 PM
Reply to: Message 46 by RoyLennigan
09-29-2005 2:05 AM


Re: Light and Energy
RL:
the energy of a photon is not dependant upon its frequency, but rather the other way around.
How about, the frequency of a photon is a byproduct of its energy. Is that better wording or more accurate?
amplitude is a measure of an aspect of the wave that corresponds to the amount of energy it has. when you turn up the volume on your speakers, you are increasing the amplitude of the sound wave they are producing, but you aren't changing the frequency of the notes being played. it works the same way with light.
But what I am trying to say is that you can't increase the amplitude of an individual photon because every individual photon's amplitude is the same regardless of the frequency. If you want more amplitude, you add more photons, which, in turn, increases the intensity of the light.
photons are grouped together that have the same frequency, amplitude, and wavelength; they all come from the same source, and have the same properties.
I'm not so sure about this. White light isn't composed of a bunch of photons all having the various characteristics you mention of white light. I think it is a bunch of photons of all different frequencies, and consequently colors, that make it appear white, as white is an amalgam of all colors. These can be separated, as I'm sure you know, through diffraction. Your statement is only true, as I understand it, for a coherent light source, i.e. laser.
All of these things being said, I maintain that the frequency of a photon is directly related to its energy and that the energy of an individual photon only changes for changing frequeincies. The amplitude of a photon of any frequency is the same, and intensity is a measure of photons (smallest possible packet of energy still related only to frequency) per unit time and related squarely to amplitude. I have seen no evidence contrary to this, only more evidence corroborating this. You have provided insight, but only relating the wave properties of photons to sound, which doesn't seem totally analogous. Perhaps there is something lost in the translation of thinking about photons as sound waves.

This message is a reply to:
 Message 46 by RoyLennigan, posted 09-29-2005 2:05 AM RoyLennigan has replied

Replies to this message:
 Message 48 by RoyLennigan, posted 09-29-2005 5:40 PM madeofstarstuff has not replied

  
RoyLennigan
Inactive Member


Message 48 of 129 (247373)
09-29-2005 5:40 PM
Reply to: Message 47 by madeofstarstuff
09-29-2005 12:10 PM


Re: Light and Energy
quote:
How about, the frequency of a photon is a byproduct of its energy. Is that better wording or more accurate?
yes, much better.
quote:
But what I am trying to say is that you can't increase the amplitude of an individual photon because every individual photon's amplitude is the same regardless of the frequency. If you want more amplitude, you add more photons, which, in turn, increases the intensity of the light.
amplitude is determined by the energy leaving the source as an interaction between the electric field and magnetic field. this energy then travels with individual photons. altogether, that energy would be the intensity (energy/unit volume * velocity). i think the only way the amplitude of a photon ever changes is when energy is lost in collisions. but if you added more photons then it would have a greater intensity, but they have to come from somewhere. i dont know if adding more photons affects the amplitude of the wave at all, because amplitude is a scalar, it measures the distance that the wave displaces. i would think, therefore, that amplitude only relates to the energy of each photon, not the overall energy. i know that you can measure the amplitude of one single photon, and you can also measure the amplitude of a group of photons from the same source, acting as a continuous wave.
quote:
I'm not so sure about this. White light isn't composed of a bunch of photons all having the various characteristics you mention of white light. I think it is a bunch of photons of all different frequencies, and consequently colors, that make it appear white, as white is an amalgam of all colors. These can be separated, as I'm sure you know, through diffraction. Your statement is only true, as I understand it, for a coherent light source, i.e. laser.
yes, of course, thats why i said it applies to a group of photons from the same source. white light is only white because we cannot differentiate all the different frequencies it consists of.
quote:
All of these things being said, I maintain that the frequency of a photon is directly related to its energy and that the energy of an individual photon only changes for changing frequeincies. The amplitude of a photon of any frequency is the same, and intensity is a measure of photons (smallest possible packet of energy still related only to frequency) per unit time and related squarely to amplitude. I have seen no evidence contrary to this, only more evidence corroborating this. You have provided insight, but only relating the wave properties of photons to sound, which doesn't seem totally analogous. Perhaps there is something lost in the translation of thinking about photons as sound waves.
frequency is related to the amount of energy in that, in a period of time, a higher frequency will carry more energy than a lower frequency. but the actual amount of energy carried by a photon is measured by amplitude. think of microwaves. the frequency of a microwave is less than that of visible light. but then how does it cook your food so fast? well, the particles have a greater amplitude. the same frequency can have different amplitudes, it depends on the source it is coming from. In fact, frequency, amplitude, wavelength, and intensity all depend on the source of the light. the same source produces the same frequency, amplitude, wavelength, and intensity, unless that source itself changes (chemically).
all waves in nature are analagous, and the information i have been giving is information directly on photons. the only info about sound i have given is from my own experience. try looking at a wider variety of sites, specifically ones that are more professional.

This message is a reply to:
 Message 47 by madeofstarstuff, posted 09-29-2005 12:10 PM madeofstarstuff has not replied

Replies to this message:
 Message 49 by JustinC, posted 09-29-2005 9:24 PM RoyLennigan has replied

  
JustinC
Member (Idle past 4844 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 49 of 129 (247456)
09-29-2005 9:24 PM
Reply to: Message 48 by RoyLennigan
09-29-2005 5:40 PM


Re: Light and Energy
I think you guys are extremely confused about the nature of light. You are trying to combine the particle model and wave model into one unified model. There is no easy way to do this. The subject that deals with predicting the behavior of photons is quantum electrodynamics.
quote:
frequency is related to the amount of energy in that, in a period of time, a higher frequency will carry more energy than a lower frequency.
This is not true. The formula E=hf determines the energy of a photon based on the frequency of light. This energy is delivered in a packet, a quantum. There is no mention of any period of time going by.
quote:
but the actual amount of energy carried by a photon is measured by amplitude.
If light was a wave, then the energy of light would be determined by the amplitude. It's not, as several experiments have shown. Look up the photoelectric effect.

This message is a reply to:
 Message 48 by RoyLennigan, posted 09-29-2005 5:40 PM RoyLennigan has replied

Replies to this message:
 Message 50 by madeofstarstuff, posted 09-29-2005 11:57 PM JustinC has not replied
 Message 52 by RoyLennigan, posted 09-30-2005 12:47 AM JustinC has replied

  
madeofstarstuff
Member (Idle past 5929 days)
Posts: 47
Joined: 08-12-2005


Message 50 of 129 (247502)
09-29-2005 11:57 PM
Reply to: Message 49 by JustinC
09-29-2005 9:24 PM


Some corroboration
Thank you Justin, I realize that I don't totally understand all about light, but am trying. I have said that something is lost in the translation of thinking about photons as sound waves, but it seems that some things are gained as well. I knew that it wasn't totally analogous.
By the way RL, just because your reasoning was sound in the following revelation, I had to find out:
the frequency of a microwave is less than that of visible light. but then how does it cook your food so fast?
Microwaves | HowStuffWorks
Just because I didn't know and it is pretty interesting.

This message is a reply to:
 Message 49 by JustinC, posted 09-29-2005 9:24 PM JustinC has not replied

  
madeofstarstuff
Member (Idle past 5929 days)
Posts: 47
Joined: 08-12-2005


Message 51 of 129 (247503)
09-30-2005 12:05 AM


Back to general relativity
I have posted some ideas I have regarding GR and am curious as to whether they are even in the right ballpark. They are now at least a couple of pages back due to the slight departure from topic. If anyone who knows a lot about this stuff can take a look, I would appreciate it, thanks.

  
RoyLennigan
Inactive Member


Message 52 of 129 (247505)
09-30-2005 12:47 AM
Reply to: Message 49 by JustinC
09-29-2005 9:24 PM


Re: Light and Energy
quote:
This is not true. The formula E=hf determines the energy of a photon based on the frequency of light. This energy is delivered in a packet, a quantum. There is no mention of any period of time going by.
frequency is measured by oscillations per unit of time. how is that not mentioning time? the way i see it, a higher frequency has more oscillations, that means the 'waves' of the electric field and the magnetic field are closer together. this means that the packets of energy are closer together. therefore more energy would be transfered in one second of a 2Hz wave than in one second of a 1Hz wave. am i right?
can you break down that equation for me? E is energy i presume, f for frequency, but what is h?
btw, madeofstarstuff, sorry if i come off as condescending at all, its just my way of getting people to think more. believe me, this debate has made me learn a lot more about light than i previously did.
This message has been edited by RoyLennigan, 09-30-2005 12:55 AM

This message is a reply to:
 Message 49 by JustinC, posted 09-29-2005 9:24 PM JustinC has replied

Replies to this message:
 Message 53 by JustinC, posted 09-30-2005 1:20 AM RoyLennigan has replied
 Message 57 by madeofstarstuff, posted 09-30-2005 1:20 PM RoyLennigan has not replied

  
JustinC
Member (Idle past 4844 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 53 of 129 (247508)
09-30-2005 1:20 AM
Reply to: Message 52 by RoyLennigan
09-30-2005 12:47 AM


Re: Light and Energy
quote:
frequency is measured by oscillations per unit of time. how is that not mentioning time? the way i see it, a higher frequency has more oscillations, that means the 'waves' of the electric field and the magnetic field are closer together. this means that the packets of energy are closer together. therefore more energy would be transfered in one second of a 2Hz wave than in one second of a 1Hz wave. am i right?
I'm not an expert on this subject either, so don't take what I say as gospel. Light was traditionally thought of as a wave in an electromagnetic field. Different types of light were ascribed frequencies. Later, around the turn of the century, it was discovered that light is actually composed of particles, called photons.
One piece of evidence for this is the photoelectric effect. Light was shined on a metallic surface. As you increase the intensity of light (I= Energy/Time/Area) the kinetic energy of the electrons coming off the surface was the same. This only makes sense if light is composed of discrete packets of energy, quantum (actually, it can also be interpreted as the electrons only absorbing a certain amount of energy, but further experiments have confirmed that light is a particle). E=hf is the formula we use to figure out how much energy these packets deliver. When light was interpreted as a wave, it was ascribed various frequencies. These frequencies can be related to the energy of the photons of that light by that formula. h is called planck's constant, and is a constant of proportionality.
Quantum electrodynamics says that light is composed of photons (actually just one type of photon, different observers view it differently from different frames of reference, i.e., red shift and blue shift). In order to see what will happen in a give experimental setup, you have to figure out every path the photon can take. This gives a probability that the photon will start at a given point and end up at a specified point.
In some setups, there is an interference pattern, i.e., it seems like it is behaving like a wave. But it is not a wave. You can dim the light so that is only sends one photon through a given experiment. Each will produce a tiny mark on a photosensitive screen. As more photons go through the setup, an interference pattern develops. Photons of different energy produce different interference patterns, and this was interpreted as different wavelengths/frequencies of light.
In different experiments, no interference develops. It all depends on the experimental setup.
This may be unclear, so look of the "Two Slits Experiment" to see what I mean.

This message is a reply to:
 Message 52 by RoyLennigan, posted 09-30-2005 12:47 AM RoyLennigan has replied

Replies to this message:
 Message 56 by RoyLennigan, posted 09-30-2005 11:44 AM JustinC has replied

  
JustinC
Member (Idle past 4844 days)
Posts: 624
From: Pittsburgh, PA, USA
Joined: 07-21-2003


Message 54 of 129 (247509)
09-30-2005 1:25 AM


You guys should pick of the book, "QED", by Richard Feynman. It is based ona series of lectures he gave to the laymen in New Zealand on the subject of quantum electrodynamics. Very informative with regard to the nature of light, and the mysterious wave/particle duality.
Feynman is probably the greatest physics teacher of all time, so the book isn't hard to read at all but gives one a deeper understanding of the subject. You may not be able to explain light to someone at the end, but you'll be able to spot mumbojumbo from a while away.

Replies to this message:
 Message 55 by Ben!, posted 09-30-2005 1:38 AM JustinC has not replied

  
Ben!
Member (Idle past 1398 days)
Posts: 1161
From: Hayward, CA
Joined: 10-14-2004


Message 55 of 129 (247510)
09-30-2005 1:38 AM
Reply to: Message 54 by JustinC
09-30-2005 1:25 AM


Page Redirection
You can listen to the lectures yourself online. Even if you guys just listen to the first one, you'll be all set.
Justin, any chance you can take a peek at my original message at Message 17?
Thanks,
Ben

I don't want a large Farva, I want a goddamn liter-a-cola.

This message is a reply to:
 Message 54 by JustinC, posted 09-30-2005 1:25 AM JustinC has not replied

Replies to this message:
 Message 58 by madeofstarstuff, posted 09-30-2005 1:24 PM Ben! has replied

  
RoyLennigan
Inactive Member


Message 56 of 129 (247655)
09-30-2005 11:44 AM
Reply to: Message 53 by JustinC
09-30-2005 1:20 AM


Re: Light and Energy
yeah i've read a little bit about planck's constant. its just hard to remember so much, especially when i've learned most of it in the last few days. the two slits experiments is a pretty easy way to show wave-particle duality, but it seemed more and more clear to me as i studied this how wave-particle duality worked. i don't know if thats from naivete of the subject or what. early in my investigations i saw how frequency was the amount of oscillations, or number of crests in the wave, per second. then what 1.61803 said made me realize that these oscillations are the movement of a photon and some other particle (what would be the particle for the magnetic field?) later i saw a diagram (A) that made me think of particles along a wave path. it seems to me like the two types of particles are revolving around each other at 90 degree angles to their direction of movement.
your second paragraph seems to further my premise that amplitude is the energy carried by individual photons, or packets as you put it, and not the entire group.
This message has been edited by RoyLennigan, 09-30-2005 11:46 AM

This message is a reply to:
 Message 53 by JustinC, posted 09-30-2005 1:20 AM JustinC has replied

Replies to this message:
 Message 61 by JustinC, posted 09-30-2005 5:54 PM RoyLennigan has replied
 Message 62 by JustinC, posted 09-30-2005 6:01 PM RoyLennigan has not replied

  
madeofstarstuff
Member (Idle past 5929 days)
Posts: 47
Joined: 08-12-2005


Message 57 of 129 (247669)
09-30-2005 1:20 PM
Reply to: Message 52 by RoyLennigan
09-30-2005 12:47 AM


Re: Light and Energy
btw, madeofstarstuff, sorry if i come off as condescending at all, its just my way of getting people to think more. believe me, this debate has made me learn a lot more about light than i previously did.
I didn't take it as condescension, it is a confusing yet fascinating topic that leads the layman such as myself down the rabbit hole. Nevertheless, we all perceive it, so it seems that there should be some way of seeing its true colors some way (pun intended).

This message is a reply to:
 Message 52 by RoyLennigan, posted 09-30-2005 12:47 AM RoyLennigan has not replied

  
madeofstarstuff
Member (Idle past 5929 days)
Posts: 47
Joined: 08-12-2005


Message 58 of 129 (247670)
09-30-2005 1:24 PM
Reply to: Message 55 by Ben!
09-30-2005 1:38 AM


Lectures
I just watched the first one and it was very interesting, thanks. I have never before heard the relation of the spinning vector determining the probability, that was a bit insightful. I will watch the rest when I have more time.

This message is a reply to:
 Message 55 by Ben!, posted 09-30-2005 1:38 AM Ben! has replied

Replies to this message:
 Message 59 by Ben!, posted 09-30-2005 1:29 PM madeofstarstuff has not replied

  
Ben!
Member (Idle past 1398 days)
Posts: 1161
From: Hayward, CA
Joined: 10-14-2004


Message 59 of 129 (247672)
09-30-2005 1:29 PM
Reply to: Message 58 by madeofstarstuff
09-30-2005 1:24 PM


Re: Lectures
Sure. Unfortunately, this topic has little to do with General Relativity. Maybe we should open up a new topic on quantum mechanics and quantum electrodynamics where we can discuss things like the nature of light.
I'm definitely glad to hear you're enjoying the lecture!

This message is a reply to:
 Message 58 by madeofstarstuff, posted 09-30-2005 1:24 PM madeofstarstuff has not replied

  
madeofstarstuff
Member (Idle past 5929 days)
Posts: 47
Joined: 08-12-2005


Message 60 of 129 (247677)
09-30-2005 1:48 PM
Reply to: Message 15 by cavediver
09-17-2005 7:35 AM


Re: My feeble attempt at understanding
Well, after thinking a little more about the rest of what you have given me, it seems you have answered my question regarding where space goes when something “occupies” it. Looks like it becomes it!
Cavediver:
when we expand to something like supergravity or string theory, we regain this wonderful picture that space and matter are the same thing.
This is strange, but I see where it parallels string theory. So, it seems that my prior post has to be rephrased to wonder what happens as one bit of curved space approaches another bit of curved space? A photon is matter with no mass, so what does it do? I suppose from its perspective it instantaneously arrives at different locations to perform various tasks, such as adding energy to an electron, or becoming the energy released by an electron. It travels through space from ours, so, in this regard, can space be considered a medium (I have had the impression that this is an incorrect way to think about space)? Because, as has been shown, space can change the wavelength of light, so space does have some effect on light. I suppose you could even say that space is why light has a wavelength.
I also posted some other ideas earlier regarding GR that I wanted you to peruse, perhaps your a bit busy with life.
This message has been edited by madeofstarstuff, 09-30-2005 01:50 PM

This message is a reply to:
 Message 15 by cavediver, posted 09-17-2005 7:35 AM cavediver has not replied

  
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