Speed of light

[jajrussel]

I've been having a thought based on a few different videos watched ,and articles read, but it kind of requires something I am not sure is gonna fly, because of generally accepted views. 

I don't consider thought to be a waste of time, but it might be easier if I had an idea of what to expect in advance?

The thought: out loud...

light exist as a wave until it is observed, at which point we call it a particle, because at that point it fits the discription of a particle. This thought actually came from a video, but maybe with some misunderstanding on my part.

One might have to accept that in observing the particle you have to interact with the wave. Which might imply that anything interacting with the wave might present a particle at any possible point. Until that point occurs we still have a wave of energy, so in essence anything that causes the wave to peak or compress might produce another wave that when observed would appear as a particle when observed.

Now accepting the thought possibility I'm thinking that to measure the speed of light I need a photon/particle. It will measure at c in a vacuum. Why a photon/particle? Cause, how do you measure a wave? Okay, I wouldn't know how to measure the speed of a particle either, but I have heard of it being done, and c is the measure in a vacuum presented.

Then accepting that the whole thought might be completely wrong I thought okay, I need a particle how do I get one? I need to add mass/energy to peak of compress the wave. It is generally accepted that if you add mass to something it slows down. Now the first problem that my completely pliable intellect encounters is.  Slows down from what to get c?

Accepting that my thinking is completely wrong, this is all nonsense. 

But then I remembered a part in the video where particles are popping in and out of existence apparently from nowhere? Okay, somebody's imagination is as pliable as mine.

Sorry,  but it has been suggested several times that I stop thinking classically and start thinking quantumly. This is essentially my first attempt.

The implication is that the wave which actually has energy presenting as zero mass might possibly move faster than the measured speed of the photon/particle which presents mass when observed. What do you think?

Is the implication simply a hurdle, or is it a wall?

I'm assuming that if it is complete nonsense you will tell me without my asking

Edited January 15, 2019 by jajrussel

[studiot]

8 minutes ago, jajrussel said:

light exist as a wave until it is observed, at which point we call it a particle, because at that point it fits the discription of a particle. This thought actually came from a video, but maybe with some misunderstanding on my part.

Simply , No.

 

Newton's original particulate theory of light (known as the corpuscular theory) predicted that the particles should move faster in a denser medium.

This was not disproved until 1750 (Foucault) was able to make comaprative measurements.

However Huygens made other less important objections

https://www.phas.ubc.ca/~stamp/TEACHING/PHYS340/SLIDES/PDF/P340-08--PP17-Light.pdf

 

Simply refracting light into a denser medium is an observation.

[Eise]

1 hour ago, jajrussel said:

Now accepting the thought possibility I'm thinking that to measure the speed of light I need a photon/particle. It will measure at c in a vacuum.

No, you just need light. The speed of light was already determined by experiments before people even knew that light is made up of photons, e.g. see Fizeau–Foucault apparatus, or Rømer's determination of the speed of light.

And then the speed of light was theoretically derived by Maxwell, also, no talk of photons necessary.

1 hour ago, jajrussel said:

Then accepting that the whole thought might be completely wrong I thought okay, I need a particle how do I get one? I need to add mass/energy to peak of compress the wave. It is generally accepted that if you add mass to something it slows down. Now the first problem that my completely pliable intellect encounters is.  Slows down from what to get c?

That train of thought is completely wrong. Photons can be measured, because they have energy and momentum, but they are massles, i.e. they have no rest mass.

Edited January 15, 2019 by Eise

[jajrussel]

48 minutes ago, studiot said:

Simply , No.

 

Newton's original particulate theory of light (known as the corpuscular theory) predicted that the particles should move faster in a denser medium.

This was not disproved until 1750 (Foucault) was able to make comaprative measurements.

However Huygens made other less important objections

https://www.phas.ubc.ca/~stamp/TEACHING/PHYS340/SLIDES/PDF/P340-08--PP17-Light.pdf

 

Simply refracting light into a denser medium is an observation.

Thank you...

I still need to read this, but from the hip wouldn't Newton be thinking along the line of gravity. Gravity tends to clump/increase density, and the more density the greater the gravitational value thus an increase in velocity, at least in thinking. The bigger the planet, the harder you fall so to speak. Thus a thought in line with the thinking, but how do you prove it?  Do you imagine the mass of a planet with enough space to move through? 

I guess I'll read the article and see what he came up with. Thanks

 

[studiot]

7 minutes ago, jajrussel said:

I still need to read this, but from the hip wouldn't Newton be thinking along the line of gravity. Gravity tends to clump/increase density, and the more density the greater the gravitational value thus an increase in velocity, at least in thinking. The bigger the planet, the harder you fall so to speak. Thus a thought in line with the thinking, but how do you prove it?  Do you imagine the mass of a planet with enough space to move through? 

I guess I'll read the article and see what he came up with. Thanks

Reading the article is better than guessing.

You would then find out that the article is additional to the biggie that I first said. I also said that.

No it was not to due to gravity.

Corpuscular theory require the light to accelerate when it enters a denser medium to meet Snell's Law and the observed fact about which way the light ray bends.

Both Newton and Huygens knew this and also knew that wave theory required the light to decelerate to meet the observations.
Neither had the means to measure which was true, that came later, as I also said.

Edited January 15, 2019 by studiot

[jajrussel]

13 minutes ago, Eise said:

No, you just need light. The speed of light was already determined by experiments before people even knew that light is made up of photons, e.g. see Fizeau–Foucault apparatus, or Rømer's determination of the speed of light.

And then the speed of light was theoretically derived by Maxwell, also, no talk of photons necessary.

That train of thought is completely wrong. Photons can be measured, because they have energy and momentum, but they are massles, i.e. they have no rest mass.

I am assuming that you are not implying that one has to know what they are measuring in order to measure it?

The measure generally helps to define. I will follow your links thank you.

As for the last sentence don't they present mass when you measure it, or would you prefer to just call it energy?

Edited January 15, 2019 by jajrussel
Isn't it always the spelling

[swansont]

10 minutes ago, jajrussel said:

As for the last sentence don't they present mass when you measure it, or would you prefer to just call it energy?

They behave in a manner consistent with having no mass. When they are absorbed by an atom, the atom behaves as if it absorbed a particle which had no mass, but had energy (E) and momentum (E/c), consistent with our models for how massless particles behave.

 

 

[jajrussel]

12 minutes ago, swansont said:

They behave in a manner consistent with having no mass. When they are absorbed by an atom, the atom behaves as if it absorbed a particle which had no mass, but had energy (E) and momentum (E/c), consistent with our models for how massless particles behave.

 

 

An atom?

I was editing this to state,that I was trying to stay consistent with what I have read or heard, occurs. But, the editing disappeared? Aren't you one of the ones who told me I needed to stop thinking classically? Wouldn't an atom be a bit large?

Edited January 15, 2019 by jajrussel

[Eise]

20 minutes ago, jajrussel said:

I am assuming that you are not implying that one has to know what they are measuring in order to measure it?

I think you can perfectly measure the speed of something, without knowing exactly what it is. As long as you have ways to measure positions and time of a moving phenomenon, you can measure its speed.

24 minutes ago, jajrussel said:

As for the last sentence don't they present mass when you measure it, or would you prefer to just call it energy?

They are what they are: quanta of electromagnetism. And as such they have energy and have momentum.

In Swansont's example, the atom absorbs a part of the energy (the atom comes into an excited state). But because of the momentum of the photon, the object of which the atom is a part, will get a tiny push in the same direction as the photon. 

[swansont]

21 minutes ago, jajrussel said:

An atom?

I was editing this to state,that I was trying to stay consistent with what I have read or heard, occurs. But, the editing disappeared? Aren't you one of the ones who told me I needed to stop thinking classically? Wouldn't an atom be a bit large?

A bit large for what? (also, that was my first post, so I made no admonishment about thinking classically in this discussion)

When an atom absorbs a photon, it recoils, because momentum is conserved. The momentum it gets is E/c, which is the momentum of a massless particle.  

16 minutes ago, Eise said:

 In Swansont's example, the atom absorbs a part of the energy (the atom comes into an excited state). But because of the momentum of the photon, the object of which the atom is a part, will get a tiny push in the same direction as the photon. 

All of the energy of the photon, in fact. One thing we observe is that you can't just absorb part of a photon's energy . Otherwise yes, precisely. 

[Eise]

11 minutes ago, swansont said:

All of the energy of the photon, in fact. One thing we observe is that you can't just absorb part of a photon's energy . Otherwise yes, precisely. 

OK. I thought a part of the energy goes into the movement of the object of which the atom is part of. If not, where goes the momentum? And is there no energy associated with this?

[studiot]

16 minutes ago, Eise said:

OK. I thought a part of the energy goes into the movement of the object of which the atom is part of. If not, where goes the momentum? And is there no energy associated with this?

That's the whole point of the quantum theory.

The amount of energy has to be exactly the right amount, like the bus fare on Aberdeen buses. Not a penny more and not a penny less.

[jajrussel]

13 minutes ago, swansont said:

A bit large for what? (also, that was my first post, so I made no admonishment about thinking classically in this discussion)

When an atom absorbs a photon, it recoils, because momentum is conserved. The momentum it gets is E/c, which is the momentum of a massless particle.  

All of the energy of the photon, in fact. One thing we observe is that you can't just absorb part of a photon's energy . Otherwise yes, precisely. 

Not in this thread, you didn't, but you pretty much finished a couple of my other threads by pointing out that I needed to stop thinking classically. In this thread I am trying not to think classically. It's no biggy ... Trying to be funny here.

But an atom is somewhat larger than,it's particles.

So, the atom recoils, and what? Is a photon emitted?  What part of the atomis absorbing the first photon?  My understanding might be wrong but my thinking was that there would be a Change in electron position resulting in a photon emission?

Which I suggested would exist as a wave until it was observed or interacted with something else , perhaps another wave in the energy field which I did not mention, but seems to be where the thought leads. The other wave may present as a particle, or the interaction might present the particle .

Again I might be wrong but isn't the picture of the electron position generally presented as a cloud. Now I'm combining the thought, cloud equals wave. For observational purposes  the electron is no more than a cloud until it has a reason to be otherwise.

Note I'm not trying to be argumentive, just trying to be clear in presentation.

It would help if I had a larger pair of reading glasses, and a keyboard that didn't seem to insist on speaking some foreign language resulting in constant corrections.

Hmm, deep breath...

 

21 minutes ago, studiot said:

That's the whole point of the quantum theory.

The amount of energy has to be exactly the right amount, like the bus fare on Aberdeen buses. Not a penny more and not a penny less.

Are you sure? Isn't it more like filling a cup. You can keep pooring water in but the size of the cup determines when the cup overflows. While the amount you poor determines the amount that overflows, while the shape determines where it goes.

Actually as your bus driver, not a penny less would apply, but if you want you can put in all the pennies you want.

Note -  The point of quantum theory does seem to be, simple. My question is what happened in the interim?

[swansont]

51 minutes ago, jajrussel said:

Not in this thread, you didn't, but you pretty much finished a couple of my other threads by pointing out that I needed to stop thinking classically. In this thread I am trying not to think classically. It's no biggy ... Trying to be funny here.

It depends on what you're doing. It's one of the things you pick up along the way — when is it appropriate to use a particular model.

Atoms behave classically (Newtonian physics) in their response to photon absorption, though the photon properties are described by relativity

Quote

But an atom is somewhat larger than,it's particles.

So, the atom recoils, and what? Is a photon emitted?  What part of the atomis absorbing the first photon?  My understanding might be wrong but my thinking was that there would be a Change in electron position resulting in a photon emission?

Th atom will eventually emit a photon, or lose its excitation via other (non-radiative) means. You can't say that one part absorbs the photon, just that the atom does, and it is now in an excited state.

Quote

Which I suggested would exist as a wave until it was observed or interacted with something else , perhaps another wave in the energy field which I did not mention, but seems to be where the thought leads. The other wave may present as a particle, or the interaction might present the particle .

Thinking of it as either/or is a summary for people who have not studied physics very much. As you go on, you learn that it's more subtle and nuanced.

Describing a photon (or anything) as being a wave or a particle is trying to shoehorn the behavior into one of the two classical descriptions we have of things. We know how particles and waves behave at the macroscopic level, so that's a convenient starting point. But photons are gonna photon.

 

Quote

Again I might be wrong but isn't the picture of the electron position generally presented as a cloud. Now I'm combining the thought, cloud equals wave. For observational purposes  the electron is no more than a cloud until it has a reason to be otherwise.

Cloud is used because there is no defined trajectory, and also because of the wave nature. You don't know where an electron is or where it's going. Just that there's a certain chance of being found in a certain region. It's nebulous. 

Quote

 Are you sure? Isn't it more like filling a cup. You can keep pooring water in but the size of the cup determines when the cup overflows. While the amount you poor determines the amount that overflows, while the shape determines where it goes.

Actually as your bus driver, not a penny less would apply, but if you want you can put in all the pennies you want.

Note -  The point of quantum theory does seem to be, simple. My question is what happened in the interim?

Pouring to overflow would be like ionization, rather than excitation. And excitation is the phenomenon here. Your pint glass also has markings for a half pint or three-quarters. If someone comes along with a pitcher that happens to have e.g. 5/8 or 7/8 of a pint, or less than half a pint, you find that you can't pour anything into the glass. It just refuses to accept any of the beverage.

 

1 hour ago, Eise said:

OK. I thought a part of the energy goes into the movement of the object of which the atom is part of. If not, where goes the momentum? And is there no energy associated with this?

It's a tiny amount, and usually ignored at least to first order in a calculation. The recoil of an atom is going to be of order 1 cm/s (depending on its mass and the energy of the photon). So a 1 or 2 eV photon might have a billionth of an eV end up as KE of an atom that was originally at rest. (a 120 amu atom has a mass of 2 x10^-24 kg, so the KE at 1 cm/s is 10^-28 J, which is 0.625 neV)

I was trying to stave off the misinterpretation that some part of the photon might remain after the interaction. I would have said the atom absorbs all of the energy, and most of that is the excitation with a very, very small bit ending up as KE.

[jajrussel]

6 minutes ago, swansont said:

It depends on what you're doing. It's one of the things you pick up along the way — when is it appropriate to use a particular model.

Atoms behave classically (Newtonian physics) in their response to photon absorption, though the photon properties are described by relativity

Th atom will eventually emit a photon, or lose its excitation via other (non-radiative) means. You can't say that one part absorbs the photon, just that the atom does, and it is now in an excited state.

Thinking of it as either/or is a summary for people who have not studied physics very much. As you go on, you learn that it's more subtle and nuanced.

Describing a photon (or anything) as being a wave or a particle is trying to shoehorn the behavior into one of the two classical descriptions we have of things. We know how particles and waves behave at the macroscopic level, so that's a convenient starting point. But photons are gonna photon.

 

Cloud is used because there is no defined trajectory, and also because of the wave nature. You don't know where an electron is or where it's going. Just that there's a certain chance of being found in a certain region. It's nebulous. 

Pouring to overflow would be like ionization, rather than excitation. And excitation is the phenomenon here. Your pint glass also has markings for a half pint or three-quarters. If someone comes along with a pitcher that happens to have e.g. 5/8 or 7/8 of a pint, or less than half a pint, you find that you can't pour anything into the glass. It just refuses to accept any of the beverage.

 

One, well maybe more than one thought before I go back to trying to figure out exactly what I'm thinking. It has been a long time since I was technically a student. I was admittedly a poor one. However, since I foolishly walked away from that position to join the army. I have spent an enormous amount of time trying to, understand what I missed.My head is like the glass you present. There is a point where you just can't pour anything else in, but I keep pouring and pouring. It gets messy. So I grab a rag, but sometimes I am puzzled why some can not see what I see in the mess I have made.

The other thing I want to point out, is that I want to thank you for Spelling out the word pour for me. Otherwise with this iPad and Gboard combination I would have spelt it poor and pooring. Remaining absolutely clueless to my error.  So, thank you...

 

[studiot]

1 hour ago, jajrussel said:

2 hours ago, studiot said:

That's the whole point of the quantum theory.

The amount of energy has to be exactly the right amount, like the bus fare on Aberdeen buses. Not a penny more and not a penny less.

Are you sure? Isn't it more like filling a cup. You can keep pooring water in but the size of the cup determines when the cup overflows. While the amount you poor determines the amount that overflows, while the shape determines where it goes.

Actually as your bus driver, not a penny less would apply, but if you want you can put in all the pennies you want.

Note -  The point of quantum theory does seem to be, simple. My question is what happened in the interim?

 

Maybe on your bus, but not in Aberdeen you can't.
If you pay by cash, you have to have the right money.

 

No its nothing like filling a cup. Particularly drop by drop whcih you can do with a cup.
The filling is all at once.
You cannot add some (a quantum or three) and then some more to make up the total.
The observational proof of that was one of the two founding experiments that led to the quantum theory.
It is called the photoelectric effect.

http://physics.bu.edu/~duffy/semester2/c34_photoelectric.html

 

 

[jajrussel]

33 minutes ago, studiot said:

 

Maybe on your bus, but not in Aberdeen you can't.
If you pay by cash, you have to have the right money.

 

No its nothing like filling a cup. Particularly drop by drop whcih you can do with a cup.
The filling is all at once.
You cannot add some (a quantum or three) and then some more to make up the total.
The observational proof of that was one of the two founding experiments that led to the quantum theory.
It is called the photoelectric effect.

http://physics.bu.edu/~duffy/semester2/c34_photoelectric.html

 

 

Okay, okay . I should have know better than to try analogy, even when joking. For me it is like wearing a T - shirt that says I'm with stupid then showing up to the party alone. Hmm, maybe in this case the analogy fits?

But, while taking a break I came across a video that might help or, maybe, she'd some light on my thinking. Note,this is not the video that caused the thought, but it does give credit to your analogy, and it might show some idea of why I referenced valence shells to waves.  The original video was really long, and if I remember correctly was hosted by Brian Green, so much more boring to the point that I would feel guilty if I presented it, and didn't include time references. This video is short and will only need time references for those who want to be stubborn.

 

Edited January 15, 2019 by jajrussel

[jajrussel]

Okay I found the original video I was thinking about and yes it was long, and yes it was hosted by Brian Greene, but it was not boring and the only reason it seemed long is because while watching the vedioi I suddenly realized that a part of the video was repeating, but I couldn't find anything that referenced the thoughts I had, which means therewas something else that trigured the thinking of what if. Bummer, I was hoping that the video would at least rationalize what I was thinking.

[jajrussel]

13 hours ago, Eise said:

No, you just need light. The speed of light was already determined by experiments before people even knew that light is made up of photons, e.g. see Fizeau–Foucault apparatus, or Rømer's determination of the speed of light.

And then the speed of light was theoretically derived by Maxwell, also, no talk of photons necessary.

That train of thought is completely wrong. Photons can be measured, because they have energy and momentum, but they are massles, i.e. they have no rest mass.

Okay, thank you...

[MigL]

You made a very profound statement, Jajrussel…
" I am assuming that you are not implying that one has to know what they are measuring in order to measure it? "

That is precisely what wave-particle duality implies.
( Swansont has already alluded to this )

[Eise]

15 hours ago, swansont said:

I was trying to stave off the misinterpretation that some part of the photon might remain after the interaction. I would have said the atom absorbs all of the energy, and most of that is the excitation with a very, very small bit ending up as KE.

Clear. Thanks.

[jajrussel]

10 hours ago, MigL said:

You made a very profound statement, Jajrussel…
" I am assuming that you are not implying that one has to know what they are measuring in order to measure it? "

That is precisely what wave-particle duality implies.
( Swansont has already alluded to this )

After reading everything over and over, again, and again. I finally realized that I was the one who said "I needed a photon" , so basically, I am the one who implied that I needed to know what I was measuring. So, my bad, Eise... I apologise.

[MigL]

QM is 'funny' that way...
If your experimental set up looks for wave properties you will detect waves.
If it looks for particle properties, then, that is what you'll detect.

[studiot]

7 minutes ago, MigL said:

QM is 'funny' that way...
If your experimental set up looks for wave properties you will detect waves.
If it looks for particle properties, then, that is what you'll detect.

Even in the photoelectric effect?

Edited January 16, 2019 by studiot

[swansont]

36 minutes ago, studiot said:

Even in the photoelectric effect?

How would you set up the photoelectric effect to look for wave behavior?