Speed C is Dependant Upon Source?

[quantumdude]

Waves are psychologial theories, which are physically subjective as we speak.

No, waves are propagating disturbances in a physical field.

The book Wu Li Masters claims physically objective originating cause of the subjective wave theory through descriptions of past experiments.

The book Quantum Mechanics by Sakurai claims that all physical phenomena are really wave phenomena. Does that mean that the objective world doesn't exist?

You're talking philosophy here, when everyone else in the joint is talking physics.

And you're wrong about photons not having "reactions". When an atom emits a photon, the atom recoils. This happens despite the fact that the photon has no mass.

 

[quantumdude]

All waves, by definition, have no mass.

Matter waves have mass.

 

[omin]

Interesting. We sense the atom recoil. Do atoms recoil between photons emiting or just when photons emit? If they only emit when the photon leaves, the photon is involved in the recoil.

The state of the atoms interia (in respect to another atom in non-uniform motion) does not determine the photons speed, but the photon emission process determines the recoil? This appears to represent a violation of N III Law.

The velocity of the body which the atom resides and the velocity of the atom in the body does not determine the photons speed from the atom? If this represents the physics, then the photon moves constant at c across something like the field aether rather and the photon's speed being determined by the atom from which it was emitted.

If the atom does determine the photons c from it, the photon moves specificaly from the atom at c. If another body of atoms were moving slower than this body (in relation to a third point) that simultaneously emitted a photon, the body of atoms traveling faster will emit a photon that travels faster than the slower moving body of atom's emitted photon.

This implies light travels at same speed from atoms through space, but approaches objects in non-linear motion at different speeds.

Or what? I'm open to understand.

 

[russ_watters]

Matter waves have mass.

You mean like sound (or maybe I don't know what a "matter wave" is...)? Sound waves ride on air, which has mass - sound waves themselves do not.

 

[Chronos]

You lost me there, Tom. Waves, by definition, have no mass, just mass potential.

 

[pmb_phy]

Matter waves have mass.

A matter wave is more of a verb than a noun. It is not a thing but rather something which describes a thing. The term matter wave usually refers to the wavelike characteristics of the probability distribution associated with a particle which has a non-zero proper mass. I spose that it can apply to a photon to since all the wavelike properties of a photon are identical to the wavelike properties of any other particle and as such they don't depend ont he particle's proper mass.

Pete

 

[pmb_phy]

Interesting. We sense the atom recoil. Do atoms recoil between photons emiting or just when photons emit? If they only emit when the photon leaves, the photon is involved in the recoil.

For simplicity consider a single isolated atom in an inertial frame of reference. In this frame the atom emits a photon. The atom recoils because the photons are emited. This can be described by saying that in order for the total momentum of the system to be conserved the atom must have momentum and that means it must move. The amount of energy the photon has is directly related to the final speed of the atom. The higher the photon energy the higher the final speed of the atom. If the atom is in a body then, for the purposes of analyzing the dynamics, you can simply consider the body to be that which emits the photon.

No matter what the final speed of the atom, the final speed of the photon is always the same, c. All that is different for photons with different momentum is the energy of the photon. The speed of the atom, however, is a function of the atoms final proper mass (the proper mass of the atom must have decreased in this process) and the atom's momentum.

Pete

 

[quantumdude]

Interesting. We sense the atom recoil.

I'm pretty sure that no one has ever "senses" an atom recoil.

Do atoms recoil between photons emiting or just when photons emit? If they only emit when the photon leaves, the photon is involved in the recoil.

They recoil as a direct result of emission (or absorption, for that matter) of photons. This is because the photon carries momentum and energy, and both are conserved quantities.

The state of the atoms interia (in respect to another atom in non-uniform motion) does not determine the photons speed, but the photon emission process determines the recoil? This appears to represent a violation of N III Law.

It doesn't violate Newton's third at all. In fact, it's entirely consistent with it. The change in momentum of the atom is precisely equal to the momentum of the photon.

The velocity of the body which the atom resides and the velocity of the atom in the body does not determine the photons speed from the atom?

No. The speed of the photon is c, regardless of the motion of the atom.

 

[quantumdude]

Matter waves

You mean like sound (or maybe I don't know what a "matter wave" is...)? Sound waves ride on air, which has mass - sound waves themselves do not.

You lost me there, Tom. Waves, by definition, have no mass, just mass potential.

What does QM teach us? It teaches us that particles act as waves. These waves are referred to as matter waves.

A matter wave is more of a verb than a noun. It is not a thing but rather something which describes a thing. The term matter wave usually refers to the wavelike characteristics of the probability distribution associated with a particle which has a non-zero proper mass.

I don't see how "matter wave" can be considered a verb. For instance, an electron is a matter wave. It doesn't do a matter wave.

I spose that it can apply to a photon to since all the wavelike properties of a photon are identical to the wavelike properties of any other particle and

Not really. As I'm sure you know, the wavelike properties of light are described by the EM wave equation. Not so with matter waves. If we want to get relativistic, then spin-0 bosons are described by the Klein-Gordon equation, and spin-1/2 fermions are described by the Dirac equation. There are more complicated equations for higher spins, but none of them is identical to the EM wave equation.

as such they don't depend ont he particle's proper mass.

Would you consider frequency and wavelength "wavelike properties"? If so, then the wavelike properties of matter waves depend on their proper mass.

 

[BobG]

They recoil as a direct result of emission (or absorption, for that matter) of photons. This is because the photon carries momentum and energy, and both are conserved quantities.

So this explains the (1+q) part of this equation?

F=\frac{F_sA}{cm}(1+q)cosi

In other words, all the photons received are received and some force is exerted to the surface receiving them.

Depending upon the reflectivity of the surface, only a certain percentage of the photons are emitted and only the departing photons affect the momentum of the surface.

The difference, the absorbed photons, have their kinetic energy converted to potential energy by raising the level of the electron's orbit.

Fairly close?

 

[quantumdude]

So this explains the (1+q) part of this equation?

F=\frac{F_sA}{cm}(1+q)cosi

I'm not familiar with the equation. What do all the variables stand for?

 

[BobG]

F=\frac{F_sA}{cm}(1+q)cosi

where F_s is solar pressure or 1367 W/m^2.
c is speed of light
m is mass of satellite
q is reflectivity (1 for totally reflective, 0 for totally absorbant)
i is incidence angle

The equation refers to the affect of solar pressure on high altitude satellites. Over time, it causes torques to build up on the spacecraft that have to be compensated for to keep the satellite's sensors/antennas/etc pointed accurately. It also affects the shape of the orbit, since solar pressure slows the satellite slightly when the satellite is headed towards the sun and speeds it up slightly when it is headed away from the sun.

 

[omin]

...The atom recoils because the photons are emited...for the total momentum of the system to be conserved the atom must have momentum... The amount of energy the photon has is directly related to the final speed of the atom...No matter what the final speed of the atom, the final speed of the photon is always the same, c. All that is different for photons with different momentum is the energy of the photon.

The change in velocity of atom (in recoil) is directly proportional to the amount of energy of the photon, but the photon's velocity isn't? How is that consistent with conservation of energy? In every physical collision, the velocity change of one entity is directly proportional to the change of velocity of the other entity, unless the quantity of change of velocity is internalized in the photon, making it unapparent to the viewer. Is this what the photon does?

I'm pretty sure that no one has ever "senses" an atom recoil.

Couldn't this be done through instrument aided sense?

 

[quantumdude]

The change in velocity of atom (in recoil) is directly proportional to the amount of energy of the photon,

Where are you getting this from?

First, the change in velocity is a vector, and the energy of a photon is not. There is no way that one could be proportional to the other. Second, even if we were talking about the change in the speed of the atom, this wouldn't be right. The change in speed of the atom is determined by:

(1/2)m_atom(v_f²-v_i²)=ΔE_photon.

That's not a direct proportion!

but the photon's velocity isn't?

Right. The photon's energy is directly proportional to its frequency.

Couldn't this be done through instrument aided sense?

Either the human senses it, or the instrument does. I stand by my original statement: humans don't sense atomic recoil. It's below the threshold of our sense of touch.

 

[BobG]

Well, I'm probably mixing apples and oranges, but it kind of feels like all the atoms in my skin are moving faster when I step into the sunlight.

This is a complicated subject when you try to figure out its relationship to things you observe.

You're receiving light. Some of the light is reflected. Some of the light exerts a force that can move objects (the same light that is reflected). Some of the light creates heat (the portion that isn't reflected). It almost does seem like we're getting too much energy out of the transaction.

 

[russ_watters]

What does QM teach us? It teaches us that particles act as waves. These waves are referred to as matter waves.

Gotcha - fair enough. I thought you meant sound waves or the like.

 

[omin]

Where are you getting this from?

First, the change in velocity is a vector, and the energy of a photon is not. There is no way that one could be proportional to the other.

I get it from this simple equation.

KE = 1/2 m * v ^2

where m = mass of photon

v = speed of photon (velocity has direction, which is included in the energy equation.)

Therefore, if photon mass is consistent, a change in speed changes photons energy. If the photon doesn't change speed, then does it's mass change during recoil?

If the photon doesn't change speed or mass during recoil, then where does the energy go? Conservation of energy represents that a change of energy on one side of the equation is proportionate to the other side of the equation, where one side is a atom and it's property recoil and the other is a photon emission.

Please explain that equation. I'm not sure if it infers the photon has change in it's mass or velocity when the atom in the equation appear to.

Either the human senses it, or the instrument does. I stand by my original statement: humans don't sense atomic recoil. It's below the threshold of our sense of touch.

If an instrument senses recoil, for us to know the instrument senses recoil, we have to sense the instrument sensing recoil. If we know it sensed it, we indirectly sense recoil. Instrument aided sense. All sense is indirect really, we don't sense the objects we sense a piece of the chain of a chain reaction. I'm basing this on the fact that thought or sense of a physical object is an expression of the object rather than the object. Which assures me, we've sensed the photon, because it has mass. Without mass, it sends no expression properties of its existence.

 

[russ_watters]

If the photon doesn't change speed or mass during recoil, then where does the energy go?

What you may be missing here is that the photon doesn't acceerate up to C like a car accelerating up to highway speed. At the instant of release, it is traveling at C. The "recoil" is therefore also an instantaneous change in energy. A photon doesn't undergo "changes" when it is emitted.

 

[quantumdude]

I get it from this simple equation.

KE = 1/2 m * v ^2

where m = mass of photon

v = speed of photon (velocity has direction, which is included in the energy equation.)

OK, so where are you getting that from?

That equation does not apply to photons. Firstly, it only applies to particles with mass (which photons don't). Secondly, it doesn't even apply to massive bodies if the speed v is comparable to c (and in the case of photons, the speed is c).

Therefore, if photon mass is consistent, a change in speed changes photons energy. If the photon doesn't change speed, then does it's mass change during recoil?

Since this is predicated on the above misconception, I have no answer for you.

If the photon doesn't change speed or mass during recoil, then where does the energy go? Conservation of energy represents that a change of energy on one side of the equation is proportionate to the other side of the equation, where one side is a atom and it's property recoil and the other is a photon emission.

I already told you: The photon energy is proportional to its frequency. For photons: E=hf (h=Planck's constant, f=frequency).

If an instrument senses recoil, for us to know the instrument senses recoil, we have to sense the instrument sensing recoil. If we know it sensed it, we indirectly sense recoil. Instrument aided sense. All sense is indirect really, we don't sense the objects we sense a piece of the chain of a chain reaction. I'm basing this on the fact that thought or sense of a physical object is an expression of the object rather than the object. Which assures me, we've sensed the photon, because it has mass. Without mass, it sends no expression properties of its existence.

The instrument doesn't aid our senses, it is replaces them. There is no such thing as "indirect sensation". Sensations are direct, first person experiences. But now we're talking philosophy again.

 

[quantumdude]

where F_s is solar pressure or 1367 W/m^2.
c is speed of light
m is mass of satellite
q is reflectivity (1 for totally reflective, 0 for totally absorbant)
i is incidence angle

OK, now I can tell you about (1+q). If a photon is absorbed by a body and never heard from again, then it transfers all its momentum to the body. This would correspond to q=0. This is a highly idealized state of affairs that is not realized in practice, but q=0 can be approached and it serves as a lower bound. Now for the other extreme: the photon is absorbed, and then promptly re-emitted in the exact opposite direction. The momentum change of the photon is not p, but 2p. This would correspond to q=1, which gives us a multiplier of 2 for the force on the body.

 

[BobG]

I get it from this simple equation.

KE = 1/2 m * v ^2

where m = mass of photon

v = speed of photon (velocity has direction, which is included in the energy equation.)

Therefore, if photon mass is consistent, a change in speed changes photons energy. If the photon doesn't change speed, then does it's mass change during recoil?

If the photon doesn't change speed or mass during recoil, then where does the energy go? Conservation of energy represents that a change of energy on one side of the equation is proportionate to the other side of the equation, where one side is a atom and it's property recoil and the other is a photon emission.

Please explain that equation. I'm not sure if it infers the photon has change in it's mass or velocity when the atom in the equation appear to.



If an instrument senses recoil, for us to know the instrument senses recoil, we have to sense the instrument sensing recoil. If we know it sensed it, we indirectly sense recoil. Instrument aided sense. All sense is indirect really, we don't sense the objects we sense a piece of the chain of a chain reaction. I'm basing this on the fact that thought or sense of a physical object is an expression of the object rather than the object. Which assures me, we've sensed the photon, because it has mass. Without mass, it sends no expression properties of its existence.

A photon has no mass. So the equation for finding the kinetic energy of an object of mass doesn't apply.

You need to use this equation:

E=\frac{hc}{\lambda}
where E = energy

c = speed of light (2.9979 x 10^8)
h = Planck's constant (6.626 x 10^-34)
and \lambda= wavelength

An alternative version is to use the frequency. Frequency is speed of light (corrected) divided by the wavelength. Energy is then Planck's constant times frequency.

The higher the frequency, the more energy. (or, the shorter the wavelength, the more energy)

Edit: Oops. Thinking faster than I could type.

 

[BobG]

OK, now I can tell you about (1+q). If a photon is absorbed by a body and never heard from again, then it transfers all its momentum to the body. This would correspond to q=0. This is a highly idealized state of affairs that is not realized in practice, but q=0 can be approached and it serves as a lower bound. Now for the other extreme: the photon is absorbed, and then promptly re-emitted in the exact opposite direction. The momentum change of the photon is not p, but 2p. This would correspond to q=1, which gives us a multiplier of 2 for the force on the body.

Right. I'm with you so far.

But, now, something should happen to the light when it is re-emitted in the opposite direction. If the light moved the mirror, then it seems like the light should lose some energy. In other words, the frequency of the reflected light would seem to have to have a lower frequency than the original received light.

 

[quantumdude]

Right. I'm with you so far.

But, now, something should happen to the light when it is re-emitted in the opposite direction. If the light moved the mirror, then it seems like the light should lose some energy. In other words, the frequency of the reflected light would seem to have to have a lower frequency than the original received light.

You're right. I failed to mention that q=1 is also an idealized case that is not realized in practice, but that it can be approached and that it is an upper bound.

 

[Doc Al]

Do reflected photons lose energy?

But, now, something should happen to the light when it is re-emitted in the opposite direction. If the light moved the mirror, then it seems like the light should lose some energy. In other words, the frequency of the reflected light would seem to have to have a lower frequency than the original received light.

You're right. I failed to mention that q=1 is also an idealized case that is not realized in practice, but that it can be approached and that it is an upper bound.

Right, q=1 represents the case of an ideal reflector. But I don't think that this formula that BobG produced addresses his real concern, which is conceptual.

I think BobG is asking: Isn't it true that the reflected photons must lose energy? After all, they produce a radiation pressure on the reflecting surface, thus do work on the surface, thus supply energy to it. That energy must come from somewhere. If the photons reflect back with the same frequency as before, then something's fishy. (Is that an accurate statement of your reasoning, BobG?)

That reasoning looks good to me. I would say that the reflected photons must be redshifted (however slightly) compared to their original frequency. Comments? Am I missing something?

 

[BobG]

Yes, exactly.

Also, I take it that all the photons are absorbed by atoms in the surface of the object being struck. The difference between being converted to heat (increasing the motion of the atoms in a random pattern) vs. being reflected is just because of the direction the photons are re-emitted.

(I've got to read something on this, this has kind of got my curiosity up - especially if you go another step further and start substituting transparent or translucent surfaces for the 1 in 1+q).

 

[russ_watters]

That reasoning looks good to me. I would say that the reflected photons must be redshifted (however slightly) compared to their original frequency. Comments? Am I missing something?

Its awful, but I don't know this one either. It seems like a situation where momentum is conserved but energy isn't. Maybe its just a matter of not taking into account mass differences, ie we tend to not think about how much velocity an individual photon will give to something with mass it hits.

Thinking about billiards balls, in a collision between a moving one and a stationary one, the moving one stops. What if the stationary one were larger than the moving one? The moving one bounces back, right? Taking the limit, if the stationary ball is almost infinitely large, it doesn't move much and the moving ball bounces back with almost the same speed/energy as it started with. Since light can't travel at almost C, it must be very, very, very slightly redshifted. Seems like maybe we just oversimplify and get rid of the "almost."

Am I close?

 

[omin]

The instrument doesn't aid our senses, it is replaces them. There is no such thing as "indirect sensation". Sensations are direct, first person experiences. But now we're talking philosophy again.

They call it physics because only physics can be sensed, the rest is religion and philosophical psychological order (pure theory).

If you say we don't sense the photon, then it's not physics. It's pure psychological mass in the brain.

Be aware, you are the one who is claiming I'm the philosopher, but you claim theories come from nonsense, which is no physical origin.

It's clear I"m after the physics here, which is only the senseable stuff!

 

[quantumdude]

They call it physics because only physics can be sensed, the rest is religion and philosophical psychological order (pure theory).

They call it physics because it's the study of things that exist. These things need not be sensed to be known. A detector whose workings are known is a valid substitute.

If you say we don't sense the photon, then it's not physics.

Wrong. Every day physicists do experiments with photons that are never sensed by humans. The detector registers their presence, and that is sufficient.

It's pure psychological mass in the brain.

What is "psychological mass"?

Be aware, you are the one who is claiming I'm the philosopher,

I said that you were drifting off into philosophy, but not that you are a philosopher. You've got a long way to go before you could be called a philosopher.

but you claim theories come from nonsense, which is no physical origin.

I never claimed that theories come from nonsense, nor did I claim that they come from "no physical origin". That's just your strawman argument.

It's clear I"m after the physics here, which is only the senseable stuff!

It's clear that you don't understand what you're talking about.

Anyway, do you have anything to say about the other corrections I made to your post? For instance, about the kinetic energy of the photon?

 

[omin]

A photon has no mass. So the equation for finding the kinetic energy of an object of mass doesn't apply.

You need to use this equation:

E=\frac{hc}{\lambda}
where E = energy

c = speed of light (2.9979 x 10^8)
h = Planck's constant (6.626 x 10^-34)
and \lambda= wavelength

The word order above are representations of thoughts. Thoughts only represent senses. Senses only represent the physically objective world. The physically objective world consists of either thought of the objective world or thought of thought existing in the mind (the subjective physical world). Therefore, these symbols are representation of physics of the objective world or they or only a theory of the mind which does not represent the objective world accurately.

What I have said is not philosophy, it's the basis of what we call theory that all physicists must understand to represent the physical world accurately.

Mass represents anything physical or a property of something physical. Or is mass also a theory existing in the mind that is outside the valid representation of the physical world?

If you guys undermine valid physical theory by asserting psychological order that represent no physics of the world is valid physics, then it's not physics and we can't talke senseably about this.

 

[quantumdude]

The word order above are representations of thoughts. Thoughts only represent senses. Senses only represent the physically objective world. The physically objective world consists of either thought of the objective world or thought of thought existing in the mind (the subjective physical world). Therefore, these symbols are representation of physics of the objective world or they or only a theory of the mind which does not represent the objective world accurately.

If we can at least agree that things that are detected by measurement apparatus (as opposed to direct sensation) constitute knowledge of the physical world, then we can move on from this issue of "sensing" and get back to your misconceptions about the kinetic energy of photons.

What I have said is not philosophy,

It very obviously is philosophy. You are defining what it means to be physical, to be objective, to be a representation of the physical world, and you are demarcating the line between the mind and the physical. That's metaphysics through and through. And your earlier comments on how sensation is prerequisite to knowledge of the physical universe is very clearly an epistemological theory. If this isn't philosophy, then nothing is.

it's the basis of what we call theory that all physicists must understand to represent the physical world accurately.

The theories that physicists develop to represent the world are already known to be accurate because they match measurements so well. The proof of the pudding is in the eating.

Mass represents anything physical or a property of something physical. Or is mass also a theory existing in the mind that is outside the valid representation of the physical world?

What difference does it make? If mass is a property of physical objects, then we can formulate physical theories in terms of it. What you are doing here is pondering the metaphysical meaning of "mass", which is a philosophical tangent issue.

If you guys undermine valid physical theory by asserting psychological order that represent no physics of the world is valid physics, then it's not physics and we can't talke senseably about this.

Will you please stop spouting off your opinions about who is undermining what theory until you demonstrate that you have mastered the theories yourself? You are still hung up on some very basic issues and you would benefit the most from getting those cleared up, rather than doing all this philosophizing (there's that word again) on things you clearly do not understand.