Particles as excitation of a field

[Strange]

1 minute ago, Butch said:

This is a consequence of a particle being a wave phenomenon... 

This is what I have been saying, review previous content! 

If a particle were a wave of any sort, it would cease to exist without reflective boundaries...  Such as a free electron. 

And several people have tried to explain why you are wrong. 

I will leave you to stew, as you are not interested in learning.

[Butch]

2 hours ago, Strange said:

Calculating the wave function (and its evolution) is how the result of the experiment was calculated. Changing the slits will change the wave function because it changes the boundary conditions.

Doing something (anything) that determines which slit the wave function goes through also changes the wave function, which is why the interference pattern disappears in that context.

Ah, but I  am learning. When I began this post I could not relate my perturbation to wave function... It was you who cleared that up for me Strange. 

Thank you. 

[swansont]

2 hours ago, geordief said:

Is it bound up with the universal speed limit (of causation)?

Since that's tied in with light speed, yes. Light can't travel faster than the universal speed limit, and travels at it, as all massless particles would.

But there's nothing that predicts a priori what that limit is.

[geordief]

1 minute ago, swansont said:

Since that's tied in with light speed, yes. Light can't travel faster than the universal speed limit, and travels at it, as all massless particles would.

But there's nothing that predicts a priori what that limit is.

And since there is (and must be)  a universal speed limit ,it follows that  the vacuum cannot have an infinite permittivity/permeability*? (separately  from the maths which seems to define the universal speed limit (in terms of permittivity/permeability)

 

*if I am right to understand  these terms as a measure of resistance to motion.

 

 

[swansont]

15 minutes ago, Butch said:

This is a consequence of a particle being a wave phenomenon... 

This is what I have been saying, review previous content! 

If a particle were a wave of any sort, it would cease to exist without reflective boundaries...  Such as a free electron. 

You're just making this up, and are providing no model of your own to support it.

Something of the form e^-(x-ct)^2 * sin((x-ct)/lambda) will give you a traveling wave packet that's stable and does not require reflection.

 

Just now, geordief said:

And since there is (and must be)  a universal speed limit ,it follows that  the vacuum cannot have an infinite permittivity/permeability*? (separately  from the maths which seems to define the universal speed limit (in terms of permittivity/permeability)

 

*if I am right to understand  these terms as a measure of resistance to motion.

I'm not sure what prevents the speed limit from being infinite. Other than it being contrary to some of our observations, nobody had much of a problem with instantaneous interaction until relativity came along (or maybe a little earlier).

[geordief]

4 minutes ago, swansont said:

 

 

I'm not sure what prevents the speed limit from being infinite. Other than it being contrary to some of our observations, nobody had much of a problem with instantaneous interaction until relativity came along (or maybe a little earlier).

Not contrary to all our observations? Are there any hypothetical observations that could lead one to believe that something had  moved faster than c  or at an infinite speed?

 

Would they be ,by definition unobservable ?

[Strange]

4 minutes ago, geordief said:

Not contrary to all our observations? Are there any hypothetical observations that could lead one to believe that something had  moved faster than c  or at an infinite speed?

There is no reason, in principle, why we couldn't measure things moving faster than c; or even instantaneously (within measurement limits). Look at the case where OPERA experiment thought they had measured faster than light neutrinos. It turned out to be an instrument error, but there is no reason the measurement couldn't be valid.

 

[geordief]

6 minutes ago, Strange said:

There is no reason, in principle, why we couldn't measure things moving faster than c; or even instantaneously (within measurement limits). Look at the case where OPERA experiment thought they had measured faster than light neutrinos. It turned out to be an instrument error, but there is no reason the measurement couldn't be valid.

 

If there had been a reflector at the other end ,wouldn't the Swiss end have seen the experiment before it began?

 

That observation couldn't have been made could it?

 

Would that "impossible experiment" disprove the other a priori?

[Strange]

16 minutes ago, geordief said:

If there had been a reflector at the other end ,wouldn't the Swiss end have seen the experiment before it began?

There is a common idea that being faster than light means going back in time (I blame Superman and The Flash for this!). It is actually a bit subtler than that. IF you can travel (or communicate) faster than light then it is possible to send a message back in time but it requires a special combination of circumstances. https://en.wikipedia.org/wiki/Tachyonic_antitelephone (Isn't that a great name for a concept!)

 If the neutrinos had travelled faster than light then the travel time (whether one way or both ways) would just be less than the travel time of light. It wouldn't be negative.

[studiot]

In the derivation of a wave equation from Maxwell's 3rd and 4th equations

[math]\nabla  \times E = \frac{{ - \partial B}}{{\partial t}}[/math]

[math]\nabla  \times H = \frac{{\partial D}}{{\partial t}}[/math]

 

Use is made of substition of the so called constitutive equations stating the properties of transmission media in general.

[math]D = \varepsilon E[/math]

[math]B = \mu H[/math]

[math]J = \sigma E[/math]

In the last of these sigma is zero, hence J is zero in free space, which affects the magnetic equation.

 

Substituting these and doing some algebra leads to

The electric wave equation.

[math]\frac{{{\partial ^2}{E_x}}}{{\partial {z^2}}} = {\varepsilon _0}{\mu _0}\frac{{{\partial ^2}{E_x}}}{{\partial {t^2}}}[/math]

The constant on the RHS is equal to the reciprocal of the wave speed, hence

[math]{c^2} = \frac{1}{{{\varepsilon _0}{\mu _0}}}[/math]

Now consider what would happen if  [math]\varepsilon [/math]  and  [math]\mu [/math]  became infinite.

The solution of the equation would become undefined and not a wave.

 

So for any wave that does exist these must be finite.

 

 

 

Edited May 1, 2018 by studiot

[Butch]

3 hours ago, geordief said:

Not contrary to all our observations? Are there any hypothetical observations that could lead one to believe that something had  moved faster than c  or at an infinite speed?

 

Would they be ,by definition unobservable ?

Here is a puzzle to consider... You look to the east and see a quasar receding at 60%c you look to the west and see a quasar receding at 60%c, what is their velocity relative to one another and what does the observer on the eastern quasar think about the western quasar?

[Strange]

2 minutes ago, Butch said:

Here is a puzzle to consider... You look to the east and see a quasar receding at 60%c you look to the west and see a quasar receding at 60%c, what is their velocity relative to one another and what does the observer on the eastern quasar think about the western quasar?

In your frame of reference, their speed difference is 1.2c. (But that is OK; nothing is moving at more than c in your frame of reference.)

They each see the other receding at 0.88c.

[Butch]

A note to all that have participated in this topic, you have helped me immensely. The information you have provided for me I can agree with completely for bosons. I think I have a better explanation for fermions. 

Swan is nearly correct I have not provided a complete model, but I did not have a complete understanding, thanks to you all (especially you Strange!) I do now. I am confident I can produce an excellent model for all of you to take apart.

5 minutes ago, Strange said:

In your frame of reference, their speed difference is 1.2c. (But that is OK; nothing is moving at more than c in your frame of reference.)

They each see the other receding at 0.88c.

I would think that they would not see each other because their difference in velocity is greater than c, but then I am a neophyte.

Edited May 1, 2018 by Butch

[Strange]

1 minute ago, Butch said:

I would think that they would not see each other because their difference in velocity is greater than c.

In their frames of reference, the velocity of the other is less then c.

Nothing can ever move faster than c.

[Butch]

5 hours ago, swansont said:

You're just making this up, and are providing no model of your own to support it.

Something of the form e^-(x-ct)^2 * sin((x-ct)/lambda) will give you a traveling wave packet that's stable and does not require reflection.

The only model I have at this point is in the abstract, I will do better.

Is a photon stable?

Edited May 1, 2018 by Butch

[StringJunky]

19 minutes ago, Butch said:

Is a photon stable?

Is 13+ billion years long enough?

[swansont]

5 hours ago, geordief said:

Not contrary to all our observations? Are there any hypothetical observations that could lead one to believe that something had  moved faster than c  or at an infinite speed?

 

Would they be ,by definition unobservable ?

If c were infinite, then the interactions could be instantaneous. It would be impossible to move faster than c.

1 hour ago, Butch said:

The only model I have at this point is in the abstract, I will do better.

Is a photon stable?

What would it decay into?

[geordief]

30 minutes ago, swansont said:

If c were infinite, then the interactions could be instantaneous. It would be impossible to move faster than c.

 

Interactions would be instantaneous**. I am not sure what would follow from that but  it is not what I would call an interaction ;everything would be undifferentiated,there would only be one global  "interaction". 

 

**or is it they would approach instantaneity as a limit in the same way as the universal speed limit would only approach infinity ?

 

 

[swansont]

9 hours ago, geordief said:

Interactions would be instantaneous**. I am not sure what would follow from that but  it is not what I would call an interaction ;everything would be undifferentiated,there would only be one global  "interaction". 

If I shine a flashlight on a detector the signal is received with zero delay, but a detector in the other direction still records nothing.

9 hours ago, geordief said:

**or is it they would approach instantaneity as a limit in the same way as the universal speed limit would only approach infinity ?

Yes. The time delay varies as the inverse of the speed. As the speed approaches infinity, the delay approaches zero.

[geordief]

11 minutes ago, swansont said:

If I shine a flashlight on a detector the signal is received with zero delay, but a detector in the other direction still records nothing. 

Yes. The time delay varies as the inverse of the speed. As the speed approaches infinity, the delay approaches zero.

If there were no upper limit to the value of c would it be incorrect to define it as "infinite" since ,once measured it is ,by definition finite?

Would the speed of any object  be dependent on an energetic input? (the size  or energy capacity of the universe as a whole)

 

Agree about the flashlight.

 

 

[swansont]

1 hour ago, geordief said:

If there were no upper limit to the value of c would it be incorrect to define it as "infinite" since ,once measured it is ,by definition finite?

Would the speed of any object  be dependent on an energetic input? (the size  or energy capacity of the universe as a whole)

We would notice that all of our measurements were consistent with that, e.g. signal delays being consistent with zero, within the measurement error. We would also notice other any effects that relied on the speed of propagation.  

[geordief]

6 minutes ago, swansont said:

We would notice that all of our measurements were consistent with that, e.g. signal delays being consistent with zero, within the measurement error. We would also notice other any effects that relied on the speed of propagation.  

Are there any theories as to why the values for permittivity and permeabiity of the vacuum are as they have been measured?

Are there any circumstances where they could (have been) be different ? Could  they be a function of any other variable ?

Have they any role in quantum theory?

 

 

[Strange]

4 minutes ago, geordief said:

Are there any theories as to why the values for permittivity and permeabiity of the vacuum are as they have been measured?

The actual numerical values are, as swansont said, because of the arbitrary man-made units we use for measurement.

In Planck units (where c=1, etc) they are both equal to 1. In a way this makes sense because you can (kind of) think of them as the "stiffness" (or something like that) of the electromagnetic field to electric and magnetic forces - one might expect these to be the same. So the only reason that permeability and permittivity appear to be different is because of the units we use.

[swansont]

11 minutes ago, geordief said:

Are there any theories as to why the values for permittivity and permeabiity of the vacuum are as they have been measured?

Are there any circumstances where they could (have been) be different ? Could  they be a function of any other variable ?

Have they any role in quantum theory?

AFAIK there is no theory that predicts the values. That's true of a lot of our physical constants.

It's hard to say how independent they are.

They have a role wherever you have a c, which is in a lot of places.

[geordief]

4 minutes ago, swansont said:

AFAIK there is no theory that predicts the values. That's true of a lot of our physical constants.

It's hard to say how independent they are.

They have a role wherever you have a c, which is in a lot of places.

Am I going (further) off topic to wonder whether   quantum fluctuations are embedded in the various fundamental  fields or ,as it were separate to them?

Edited May 2, 2018 by geordief