Does light have a mass?

James R, in all honesty, these relativistic reasons are a fake argument

you said:

mainstream explanation --> mass increase
argument --> source of acceleration itself is the cause
counter-argument --> no, mass increase

it's not an argument, it's just repeating the 1°

@Crisp

When I am driving around with my car and I am going faster than the one whose driving in front of me, and I bounce against it, will I take advantage of the collision and gain speed?
Besides, the photon IS going faster. How will de particle be able to run into the photon?

 

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Hi all,

Tom,

"Acceleration decreasing with the increase of speed is not something that is limited to quantum mechanics, we see it in everyday objects. (...) But you believe that particles in particle accelerators act DIFFERENTLY than all the other objects in our everyday world. You believe that the decreased acceleration HAS to be the result of increasing mass.""

Some explanation on the observed effect in everyday objects would be welcome. However, I think you are referring to mechanical effects.

Yes, I do believe particles in particle accelerators behave differently than all other objects in our everyday world. There are plenty of quantummechanical phenomena that occur constantly on a particle scale and never on macroscopic scale.


C'est moi,

"When I am driving around with my car and I am going faster than the one whose driving in front of me, and I bounce against it, will I take advantage of the collision and gain speed?
Besides, the photon IS going faster. How will de particle be able to run into the photon?"

A sideways collision (not under a 90 degree angle) for example (but I do believe we're looking at the situation too much in a classical way, quantum collisions really don't just work that way). However, I know too little of the quantum nature of fields to exactly say how the photons interact with the particles; I'll look this up and come back on this.

Bye!

Crisp

 

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okay Crisp

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James R, I do understand it. Obviously, you are ignoring what I am saying and twisting my words. You cannot object an argument to something by just repeating the thing. Are you brainwashed?

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Crisp,

"Some explanation on the observed effect in everyday objects would be welcome. However, I think you are referring to mechanical effects.

Yes, I do believe particles in particle accelerators behave differently than all other objects in our everyday world. There are plenty of quantummechanical phenomena that occur constantly on a particle scale and never on macroscopic scale."

Why do you assume that particles in particle accelerators don't follow classical mechanics?? You assume that since subatomic particles are involved, quantum mechanics must be involved. This does not have to be the case.

Example 1: Lets take into consideration a bunch of hydrogen nuclei in a container. These nuclei can be considered particles, yet their motion and reaction can be explained using only classical mechanics. They will bounce against each other just like rubber balls. There is nothing unusual until you increase the pressure. If the pressure is high enough then fusion begins to occur. Only after fusion begins to occurs, do you have to start taking quantum mechanics into consideration.

Example 2: You have a bunch of protons and electrons in a container. The electrons and protons attract each other. The resulting speed and motion of particles can be described COMPLETELY using only classical mechanics. Only after one of the electrons joins with a proton to create an atom, do you even have to begin to consider quantum mechanics.

To clarify my argument, I believe that quantum mechanics applies in particle interactions where the particles themselves are changed or converted to other or new particles. In cases where particles are not changed in the reaction, like in particle accelerators, the result of the interaction can be explained using ONLY classical mechanics.

Note: What would happen if I replaced a particle in a particle accelerator with a charged metal ball?? Do you think that quantum mechanics would be involved in this case as well???

Tom

 

James R,

"According to the correspondence principle, all quantum mechanical results reduce to their classical equivalents when large numbers of particles or large quantum numbers or large masses are involved."

I completely agree with you. I was just stating that many single particle interactions can be explained using only classical mechanics. In many particle interactions, quantum mechanics isn't even an issue. As stated earlier, quantum mechanics seems to only apply in particle interactions where one or more particles are transformed or changed into new particles.

I believe that classical mechanics is sufficient to explain all interactions in particle interactions where the particles themselves are not changed or converted into new particles.


Tom

 

Hi Tom,

"I believe that classical mechanics is sufficient to explain all interactions in particle interactions where the particles themselves are not changed or converted into new particles."

Can you give us an example where this would be true (excluding the trivial and non-interesting "plain collision with no side-effects" interaction) ?


From your previous post:

"Why do you assume that particles in particle accelerators don't follow classical mechanics?? You assume that since subatomic particles are involved, quantum mechanics must be involved. This does not have to be the case."

You have a point here. It is possible that classical Newtonian mechanics could give an fair enough description of a certain proces that takes place in a particle collision. However, that is not a general truth (especially at higher energies where relativistic effects involving particle creation, or at low energies where spin-effects arise with some collision types). So I'd rather put my money on QM than on classical mechanics when considering a general collision (note that collisions involving only two particles are virtually non-existant, you usually have beams of millions of particles colliding at all sorts of energies under all sorts of situations - at that point I am very confident that classical mechanics will fail to explain all collisions. I think you'd have to be rather lucky to get even 0,1% of all collisions right under a modern accelerator experiment).


Bye!

Crisp

 

Crisp,

Do you believe that a particles acceleration in a particle accelerator would be constant if the mass of the particle remained constant???

As far as I know, force has three properties: strength, direction, and speed. It has been found that under all conditions, acceleration of an object decreases as the object approaches the speed of the force.

But you are argueing that this does not apply in particle accelerators, even though you claim that you don't understand the interaction between electric or magnetic fields and the charged particles in the accelerators.

Doesn't your argument sound illogical to you. You are basically saying: Event A always occurs, with the exception of particle accelerators where event B occurs, even though I don't know why event B happens, and by the way, event A is indistingushable from event B.

You keep on insisting that the interaction of the electric fields with the particles in the particle accelerators follow the rules of quantum mechanics instead of classical mechanics. But what if I replaced the charged particle in the particle accelerator with a charged metal ball???

I guess since a metal ball is much larger than particles, only classical mechanics would apply in that case, right????

Basically you don't want to even consider this idea, because it would be such an enormous blow to relativity.

It's OK, I understand. It's hard to let go of something that you loved for so long.

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Tom

 

Hi Tom,

D*mn, you're good

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. But I still have to disagree with you:

"Do you believe that a particles acceleration in a particle accelerator would be constant if the mass of the particle remained constant??? As far as I know, force has three properties: strength, direction, and speed. It has been found that under all conditions, acceleration of an object decreases as the object approaches the speed of the force."

Some remarks. First of all, I still think you're applying classical mechanics in a situation where it has been proven not to work. Classical mechanics simply cannot explain some effects in collision experiments. Examples: it is not able to predict why the speed of light seems to be the upper speed limit for massive particles (= relativistic aspect). Differential cross-sections are predicted unaccurately in neutron-neutron or neutron-proton collisions (= quantum aspect). Don't ask me why classical mechanics fails at that point, because I can only give you reasons that are used in the theory of relativity or quantum mechanics (a theory cannot be disproved by that theory alone).

Ok, now let's assume for one second that particles in particle accelerators and collisions obey Newton's laws. In that case: yes, the acceleration of a particle remains constant: F = ma, F doesn't change, m is constant and hence a also has to be constant. From a classical point of view, the acceleration a cannot decrease when m remains constant (ofcourse we assume that the force accelerating the object remains constant too). So if you say that in all situations, the acceleration seems to decrease, then I really wonder how - purely from a classical mechanical point of view - you are going to explain the increase of mass to account for the decrease of acceleration.

"But you are argueing that this does not apply in particle accelerators, even though you claim that you don't understand the interaction between electric or magnetic fields and the charged particles in the accelerators."

I claim that I don't understand the quantum-field interaction between electric fields and charged particles. The Newtonian (or "regular" quantum-mechanical) interaction is not really a problem.

I should also remark that I never talked about acceleration in any of my posts on particle accelerators (except for mentioning the word "accelerator" ofcourse

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). Acceleration and force are "obsolete" concepts in modern theories: the interaction between particles, their position and momenta are nowadays described completely in terms of what is called a potential (which is a mathematical model for the interaction).

"You keep on insisting that the interaction of the electric fields with the particles in the particle accelerators follow the rules of quantum mechanics instead of classical mechanics. But what if I replaced the charged particle in the particle accelerator with a charged metal ball??? I guess since a metal ball is much larger than particles, only classical mechanics would apply in that case, right????"

As James R pointed out, everything is quantum mechanics. The distinction we are making is really artificial. However, assuming that you only need a precision of 10^(-3) or something to explain an effect, you can resort to classical mechanics in some situations (plainly and simply: because it is easy compared to QM).

On your question: that depends on the size of the ball. If it only consists of a few hundred atoms, then individual quantum effects probably still have to be taken into account. A "large" metal ball is described best using classical mechanics, since QM will be too difficult to calculate exactly there, and for large objects, quantum effects become neglegible.

"It's OK, I understand. It's hard to let go of something that you loved for so long."

If you read some of my other posts, then I am sure you'll realize that I am not one of them die-hard physicists who cannot bear the thought of a theory being wrong. However, I do my best to explain what physics has to say on an idea, and that does not necessarily mean that I am happy with the explanation either.

Bye!

Crisp

 

The photon-catch-up-with electron effect

Hi c'est moi,

Concerning the interaction between electrons and photons of an electric field (and the catching up explanation for the electron not being able to attain the speed of light). I've been thinking on it, and discussed with a few fellow students on the matter. Here's what we came up with:

First of all, somebody (correctly) raised the point that the description we both give is only a characterization of what really happens, and that both explanations do not necessarily exclude eachother. Increasing mass being responsible for the electron not being to reach lightspeed is one way to put it, while the catching-up model is something that puts it into easier words (I quote: "het bekt beter

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" (Dutch)).

I've been thinking on it further and I think we both used a wrong interpretation of what really happens. I've come to think that the electric field is present at the location the electron passes, and that the field functions as a source of energy. If an interaction between the electric field and the electron occurs, then the electron simply absorbs one quantum of energy of the field (= one photon). In other words: the field does not consist of photons just fuzzing around, waiting for an electron to absorb one of them. The field is not equivalent with photons, it is the interaction that is quantized into photons (this is exactly one of the fundamental properties of quantummechanics).

I've come up with the following example to disprove the "electric field = photons fuzzing about" statement: Consider a single electrically charged particle. We probably both agree that this particle sets up an electric field in space. If the electric field consisted of photons being radially spread out by the electron, then I wonder where the electron gets all the energy to keep on emitting photons to keep the field intact (in principle, you can maintain the field for an infinite amount of time, and hence the electron would somehow need an infinite amount of energy to maintain that field). This example confirms the idea that the electric field is an underlying medium that allows interaction. If an interaction occurs (eg. another charged particle passes through the field of that single charged particle), then the passing particle simply instantly absorbs a photon of the electric field.


Bye!

Crisp

 

Crisp,

"Ok, now let's assume for one second that particles in particle accelerators and collisions obey Newton's laws. In that case: yes, the acceleration of a particle remains constant: F = ma, F doesn't change, m is constant and hence a also has to be constant. From a classical point of view, the acceleration a cannot decrease when m remains constant (ofcourse we assume that the force accelerating the object remains constant too). So if you say that in all situations, the acceleration seems to decrease, then I really wonder how - purely from a classical mechanical point of view - you are going to explain the increase of mass to account for the decrease of acceleration."

It's good that you are taking into consideration that the collisions might obey Newton' laws, but you don't seem to understand what causes the decreasing acceleration. Let me explain:

The kinetic energy of a moving object(lets say object A) is:

E=m*v^2/2

where m is the mass, and v is the velocity of object A

If object A were to hit object B, while object B is at rest the total kinetic energy of object A would be transferred to object B because the velocity of object A would become zero. The kinetic energy of object A would be converted to a force on object B. This force on object B would cause object B to accelerate:

a=F/m(object B)

If object B is moving away from object A at the speed of v2, and object A was to collide into object B, the energy converted to force would be:

E=(m*v1^2/2)-(m*v2^2/2)

As you can see, the energy converted to force would be less since object A's velocity would not decrease to 0, it would only decrease to v2. Since the energy transferred would be less, the resulting force would be less. Since the force would be less, the acceleration would be less.

Now let me explain this effect without using formulas:

Assume you are driving in a car at 60 km/h and you hit another car which is at rest. As you can imagine, the force would probably kill you.

But what would happen if you were driving at 60 km/h and you hit the car in front of you that was traveling 55 km/h???

The resulting force would be much less. The reason for this is because your speed would not decrease to zero, it would decrease to 55km/h. Therefore your car would conserve most of it's kinetic energy instead of it being converted into force on the second car.

As you can see from the example above, the smaller the difference in speed between the two vehicles, the smaller the resulting force of the impact. Since the force is less, the acceleration is smaller as well.

This would mean that acceleration of an object will decrease as the objects speed approaches the speed of the force. If you were to use this well-known concept in particle accelerators, then the particles acceleration would decrease the closer the particles speed got to the speed of light(the speed of the electric and magnetic fields).

I hope this clears thing up.


Tom

 

Hi Tom,

"If object A were to hit object B, while object B is at rest the total kinetic energy of object A would be transferred to object B because the velocity of object A would become zero."

Not necessarily true, all you require in an elastic collision (= no deformation of the objects) is the conservation of energy and momentum. It is very well possible that in that collision you describe, both A and B scatter under a certain angle, without violating any of those conservation laws.

The same goes for the rest of your explanation. The situations you describe are some of many possible scenarios. Also, the collision between two objects and the resulting change in momenta is totally different from the acceleration in an electric field.

Bye!

Crisp

 

Crisp,

I wasn't attempting to include all the factors in a collision. I was only giving a simplified example to explain momentum transfer in an "ideal" collision. I thought that this was obvious.

"Also, the collision between two objects and the resulting change in momenta is totally different from the acceleration in an electric field."

It doesn't matter if it's different or not. Whether you believe that an electric field consists of photons being emmited from an electron, or if you believe that an electric field is a stationary extension of the electron, the results are the same. In both cases there is an interaction that causes the force. The nature of the interaction is irrelevent, as well. All that matters is that the speed of the interaction is light speed, therefore, the speed of the resulting force is light speed. And if the speed of the force is light speed, the acceleration of all objects pushed by this force decrease as the objects approach the speed of the force.

Even in the "electric field" model you proposed, you will find that this is the case. You suggested that there is a photon interaction only when a charged object enters an electric field. If this is the case, how fast is this interaction?? The answer is that the interaction occures at light speed, and therefore, the velocity of the resulting of force is light speed, as well.

Only in an instantaneous force is acceleration independent of speed. And currently there is no evidence of any instantaneous forces existing(with the exception of quantum entanglement).

Tom

 

James R,

Okay, and one of the virtual photons can then be absorbed by a charged particle as the field interaction. The difference in energy is paid back by ... ? I would say a decrease in field energy, but I remember from somewhere that the field energy density is only dependent on the field-generating particle (I am talking about a classical result, perhaps this changes in QED). Since the original particle does not change, I suspect the field wouldn't either.


Tom,

"You suggested that there is a photon interaction only when a charged object enters an electric field. If this is the case, how fast is this interaction?? The answer is that the interaction occures at light speed, and therefore, the velocity of the resulting of force is light speed, as well."

The field spreads out at the speed of light. If one moment there is no charged particle, and the moment after you put one there, then it will generate a field that, in case of a single charged particle, spreads out radially into space at the speed of light. However, the "speed of the interaction" does not necessarily have to be the same. I suspect it is (since photons are the mediators of the coulomb force), but the situation could be a bit more complicated.

 

Hi James R,

"Hmmm....I'm beginning to wish I paid more attention in quantum field theory classes."

LOL, that makes two of us

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... Ohwell, the quantum field theory exam is only... 5 weeks away for me, so I guess it is about time I open the book

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.

Crisp

 

Crisp,

I found your explanation of "electric fields" interesting, but a little too complicated. I see no need for photons in the electric field interaction at all. Here's my explanation of electric fields:

An electric field is just an extension of an electron. The only difference between an electron and it's field is that an electron is more dense. Therefore, charged particles can travel through an electric field, but not through the electrons themselves(at least not most of the time). The quantum packets of space that are in the center of the electron have the highest quantum of electric charge. The further you go from the center of the electron, the smaller the quantum charge of the space packets.

When two electrons are forced close to each other, the quantum charges of the space packets of the two electrons are forced to consolidate. In other words, two neighboring space packets with a lower quantum charge are forced to become one space packet with a higher quantum charge. Unfortunatly, these new quantum charged are unstable for some reason, so they attempt to split into two packets. Since there is no room for two packets of space, the force is transferred to the electrons forcing them to move away from each other.

A similiar event occures with two opposite charges except they try to consolidate the packets of space, thereby eliminating space between the particles, thereby moving the particles closer.

The explanation I have given would require there to be "magic numbers" of charged quantums of space. If the sum of two neighboring quantum charged packets equals these "magic numbers" the two packets of space would consolidate, otherwise they would continue to split until the resulting individual space packets are stable.

Unfortunatly, I still haven't worked out the "magic numbers", but I'm getting close.

Note: This same model can be used to describe gravity. Finally a model that unites fundamental interactions instead of segregating them(like Einsein's "curved space" theory).

Tom