Light some interesting questions and an observation

[trogan]

I have some very vexing questions regarding light. We seem to know so little about it.

1. What happens to light when it is not traveling ?

2. Does it accelerate in reaching C ? If not does it "jump" to C ?

3. Can it be destroyed ? If not it seems to me that the amount of light in the universe is constantly increasing. Is this a valid statement ?

4. Why does it travel in a particular direction and what determines this ?

5. Two light beams traveling in opposite directions will meet at a speed of 2C (this has to be true if C is a constant). Doesn't this contradict Einsteins theory of relativity regarding C.

6. How is light absorbed into a particle ? ie what is the mechanism.

7. Where does it end up ?

8. On a slightly different topic, I have a question regarding time and the speed of an object. If time slows down for an object as it speeds up, is this not explained by the fact that it also becomes more massive as it speeds up ? As a result of this, interactions with photons will take longer thus causing a subjective slowing down of time as far as the object is concerned. In other words time is about rate of change. Are speed and mass equivalent ?

Tony

 

[Dale]

Hi trogan, welcome to PF!

I have some very vexing questions regarding light. We seem to know so little about it.

On the contrary, we know more about electromagnetism than any of the other four fundamental forces.

1. What happens to light when it is not traveling ?

It always travels at c. If something is not traveling then it is not light.

2. Does it accelerate in reaching C ? If not does it "jump" to C ?

It always travels at c, its acceleration can only change its direction or its frequency, not its speed.

3. Can it be destroyed ? If not it seems to me that the amount of light in the universe is constantly increasing. Is this a valid statement ?

Certainly it can be destroyed. To prove this simply go into a darkroom with a flashlight, turn it off, and note that it becomes dark.

4. Why does it travel in a particular direction and what determines this ?

Maxwell's equations determine such behavior, although in appropriate circumstances you can use "ray optics" as a simplification.

5. Two light beams traveling in opposite directions will meet at a speed of 2C (this has to be true if C is a constant). Doesn't this contradict Einsteins theory of relativity regarding C.

No.

6. How is light absorbed into a particle ? ie what is the mechanism.

Light consists of electric and magnetic fields which can interact with electrically charged particles, typically the electrons.

7. Where does it end up ?

As mentioned above, it is destroyed. However, its energy is transferred to the absorbing particle which has increased energy after the absorption.

8. On a slightly different topic, I have a question regarding time and the speed of an object. If time slows down for an object as it speeds up, is this not explained by the fact that it also becomes more massive as it speeds up ? As a result of this, interactions with photons will take longer thus causing a subjective slowing down of time as far as the object is concerned. In other words time is about rate of change. Are speed and mass equivalent ?

I hadn't heard that interactions with photons take longer for particles with larger mass. If that is correct it is news to me.

 

[trogan]

Hi trogan, welcome to PF!On the contrary, we know more about electromagnetism than any of the other four fundamental forces.It always travels at c. If something is not traveling then it is not light.It always travels at c, its acceleration can only change its direction or its frequency, not its speed.Certainly it can be destroyed. To prove this simply go into a darkroom with a flashlight, turn it off, and note that it becomes dark.Maxwell's equations determine such behavior, although in appropriate circumstances you can use "ray optics" as a simplification.No.Light consists of electric and magnetic fields which can interact with electrically charged particles, typically the electrons.As mentioned above, it is destroyed. However, its energy is transferred to the absorbing particle which has increased energy after the absorption.I hadn't heard that interactions with photons take longer for particles with larger mass. If that is correct it is news to me.

Thanks for your reply.

I must admit I am totally confused by electromagnetic field theory. Fields I thought had been discredited by quantum theory. So Maxwell's equations , while being useful, have little realtion to reality. Instead an electromagnetic wave according to quantum theory is supposed to consist of photons isn't it ? i.e. light. It seems no-one has much of a clue and this has now been going on for over a century ! Problem is few seem willing to admit this.

 

[Dale]

I must admit I am totally confused by electromagnetic field theory. ... It seems no-one has much of a clue and this has now been going on for over a century ! Problem is few seem willing to admit this.

Please don't over generalize your own sense of confusion into an erroneous conclusion that no-one understands these concepts.

Fields I thought had been discredited by quantum theory.

Why would you think that? The modern quantum theory that governs light is called quantum electrodynamics (QED). It is a quantum field theory, so fields are a core concept in QED.

So Maxwell's equations , while being useful, have little realtion to reality. Instead an electromagnetic wave according to quantum theory is supposed to consist of photons isn't it ? i.e. light.

On the contrary, Maxwell's equations have an overwhelming amount of experimental evidence supporting them. The only reason that QED and later theories are even considered is that they reduce to Maxwell's equations in the appropriate limits.

I don't know how much scientific background you have, but it is absolutely essential that any new theory reduce to earlier experimentally validated theories in the domain of those experiments. Otherwise the new theory would immediately be falsified by existing experimental evidence. That is why we continue to teach Newtonian mechanics in college.

 

[trogan]

Please don't over generalize your own sense of confusion into an erroneous conclusion that no-one understands these concepts.

Why would you think that? The modern quantum theory that governs light is called quantum electrodynamics (QED). It is a quantum field theory, so fields are a core concept in QED.

On the contrary, Maxwell's equations have an overwhelming amount of experimental evidence supporting them. The only reason that QED and later theories are even considered is that they reduce to Maxwell's equations in the appropriate limits.

I don't know how much scientific background you have, but it is absolutely essential that any new theory reduce to earlier experimentally validated theories in the domain of those experiments. Otherwise the new theory would immediately be falsified by existing experimental evidence. That is why we continue to teach Newtonian mechanics in college.

I am a software developer with a chemistry background. I am researching State Machines and am looking to apply the results to generating models of reality. I have read extensively on quantum theory. I am not saying that there is anything wrong with current theory, including Newtonian, just that the theory does not come close to giving me a clear picture of reality. The questions I posed re light I think are questions that need answering before a clearer picture of reality arises. None of your answers give me the clarity I require. For example it is my understanding that a photon is emitted by an electron when it jumps to a lower orbit. I wonder what the mechanism for this is and how the hell the photion is emitted at a speed of c without any accelaration involved. The fact that nonone really knows what a electron is (or for that matter a photon) doesn't help matters !

 

[mikelepore]

In science, things are defined by a list of things that they do. If you can make a list of some true statements about the behavior of an electron, that's what an electron is. Science has no other "is."

There's no need to refer to a mechanism for an electron to emit a photon, because we don't have knowledge of some smaller steps that such a mechanism would have to consist of. If we had evidence for the existence of several more fundamental processes of which this process were known to be a combination, then we would have the challenge to determine which among the building blocks are put together to comprise this composite process.

To form a "picture of reality", perhaps the most basic fact would be that conscious beings who receive all their information through senses must have as their limit of knowledge the sum of all information that has ever been accumulated through everyone's senses and using all existing instruments. To ask what is more basis than the most basic thing that has ever been discovered, the words can be formed into the question, but it's not the task of science to work on it.

 

[trogan]

In science, things are defined by a list of things that they do. If you can make a list of some true statements about the behavior of an electron, that's what an electron is. Science has no other "is."

There's no need to refer to a mechanism for an electron to emit a photon, because we don't have knowledge of some smaller steps that such a mechanism would have to consist of. If we had evidence for the existence of several more fundamental processes of which this process were known to be a combination, then we would have the challenge to determine which among the building blocks are put together to comprise this composite process.

To form a "picture of reality", perhaps the most basic fact would be that conscious beings who receive all their information through senses must have as their limit of knowledge the sum of all information that has ever been accumulated through everyone's senses and using all existing instruments. To ask what is more basis than the most basic thing that has ever been discovered, the words can be formed into the question, but it's not the task of science to work on it.

It seems to me that if you dig deep enough into reality and all you come up with are concepts then that is possibly what reality consists of. In which case it is likely we are a computer simulation of some kind (a la The Matrix). It is certainlty true that at some time in the future we will create computer-based entities that a. are more intelligent than we are b. consider themselves to be "real".

 

[Dale]

None of your answers give me the clarity I require.

Then I would recommend taking some courses on the subject. A few paragraphs on an internet forum are never going to be a proper substitute for organized and complete lectures and doing lots of homework. If you want a clear understanding then you will need to make the same effort that others with a clear understanding have made.

 

[trogan]

Then I would recommend taking some courses on the subject. A few paragraphs on an internet forum are never going to be a proper substitute for organized and complete lectures and doing lots of homework. If you want a clear understanding then you will need to make the same effort that others with a clear understanding have made.

Thanks for your advice.

Yep, I understand what you are saying and agree that an in-depth knowledge of a subject is a great thing to have. I am essentially involved in a creative endeavour and am using my intuition as to what I think I need to know. So am pursuing fairly narrow lines of thought that may make a course a bit of an overkill. My very broad (although somewhat undisciplined) knowledge of physics is my basis for this. I tend to be more interested in concepts than maths although I will delve into the mathematics of something if I find I need to clarify it.

 

[Dale]

So am pursuing fairly narrow lines of thought that may make a course a bit of an overkill.

I understand, everyone's time is limited. But it is rather presumptuous to make general statements that nobody knows something about a specific subject when you are consciously avoiding learning what many people do know about that subject.

 

[Yeti08]

Let me preface this by saying that I am an engineer, not a physicist.

It always travels at c, its acceleration can only change its direction or its frequency, not its speed.

It doesn't always travel at c, as c is the speed of light in vacuum. Refraction relies on the fact that light passing through different mediums will travel at different speeds. Light has also been slowed down http://en.wikipedia.org/wiki/Slow_light" . For the original question, light is massless, so there is no acceleration period like a particle with mass would require, which is what I think you were asking.

 

[Dale]

It doesn't always travel at c, as c is the speed of light in vacuum. Refraction relies on the fact that light passing through different mediums will travel at different speeds.

True, I was being sloppy. I meant in vacuum.

 

[SystemTheory]

I am researching State Machines and am looking to apply the results to generating models of reality.

Have you read The Dreaming Universe by Fred Alan Wolf? This book implies that dreams share the same properties as quantum events. I think consciousness is built upon a reflecting of thought waves in a structure, like a laser generating coherent light.

mirror ( < light > ) mirror

The light reflects multiple times between two spherical mirrors and becomes coherent. The body may generate a form of mutual reflection in the neural pathways to generate coherent consciousness or self. The neurons responsible for ape-like imitation are called "mirror neurons." This is slight off topic re. properties of light but relevant to models of reality and electromagnetic waves involved in signal processing.

 

[trogan]

If something is not traveling then it is not light

Ok, so I guess a photon is destroyed when it is absorbed by an electron. And the electron has the capability to create it anew when it emits a photon. So it would seem light is not really slowed down by a transparant medium. It is constantly being destroyed and recreated by electrons and in between always travels at c.

I wonder about the supposed impossibility of stopping light when I read articles like the followinghttp://www.wired.com/science/discoveries/magazine/15-11/st_alphageek"

Also, from my search of the internet there seems to be increasing evidence for super-luminary travel by photons.

 

[Born2bwire]

Ok, so I guess a photon is destroyed when it is absorbed by an electron. And the electron has the capability to create it anew when it emits a photon. So it would seem light is not really slowed down by a transparant medium. It is constantly being destroyed and recreated by electrons and in between always travels at c.

I wonder about the supposed impossibility of stopping light when I read articles like the followinghttp://www.wired.com/science/discoveries/magazine/15-11/st_alphageek"

Also, from my search of the internet there seems to be increasing evidence for super-luminary travel by photons.

Not really so much by the electrons in the atomic orbitals. An atom only has discrete energy levels that the electrons can transition to, this greatly restricts the frequencies of light that can be emitted. So if the only mechanisms were the electrons and their orbitals, we would not have things like mirrors and such. Instead, the energy of the photon is absorbed by the bulk material, by the bonds between the atoms/molecules. This causes vibrations called phonons. Phonons have a very dense distribution of energy states. In most situations we consider it to be continuous since the separation between the energy states is less than the thermal energy of our environment. This allows for a wide range of frequencies of photons to be emitted.

A full understanding of light would require rigorous understanding of quantum field theory which is far beyond the average person's exposure to physics. A good compromise is to explain the classical theory of electromagnetics and throw in a few quantum ideas about light, like photons and energy levels. This effectively describes light for just about any situation, in fact, classical electrodynamics is still a huge area of active research since it is still very applicable.

 

[trogan]

Hi trogan, welcome to PF!On the contrary, we know more about electromagnetism than any of the other four fundamental forces.It always travels at c. If something is not traveling then it is not light.It always travels at c, its acceleration can only change its direction or its frequency, not its speed.Certainly it can be destroyed. To prove this simply go into a darkroom with a flashlight, turn it off, and note that it becomes dark.Maxwell's equations determine such behavior, although in appropriate circumstances you can use "ray optics" as a simplification.No.Light consists of electric and magnetic fields which can interact with electrically charged particles, typically the electrons.As mentioned above, it is destroyed. However, its energy is transferred to the absorbing particle which has increased energy after the absorption.I hadn't heard that interactions with photons take longer for particles with larger mass. If that is correct it is news to me.

Not really so much by the electrons in the atomic orbitals. An atom only has discrete energy levels that the electrons can transition to, this greatly restricts the frequencies of light that can be emitted. So if the only mechanisms were the electrons and their orbitals, we would not have things like mirrors and such. Instead, the energy of the photon is absorbed by the bulk material, by the bonds between the atoms/molecules. This causes vibrations called phonons. Phonons have a very dense distribution of energy states. In most situations we consider it to be continuous since the separation between the energy states is less than the thermal energy of our environment. This allows for a wide range of frequencies of photons to be emitted.

A full understanding of light would require rigorous understanding of quantum field theory which is far beyond the average person's exposure to physics. A good compromise is to explain the classical theory of electromagnetics and throw in a few quantum ideas about light, like photons and energy levels. This effectively describes light for just about any situation, in fact, classical electrodynamics is still a huge area of active research since it is still very applicable.

Thanks for that Born2bwire. It is exciting to see ever more complex states of matter being discovered. I suspect what we have discovered to date is just a small percentage of the totality of possible states. Can you tell me is a phonon a particle in its own right or a photon in a particular state ?

 

[Born2bwire]

Thanks for that Born2bwire. It is exciting to see ever more complex states of matter being discovered. I suspect what we have discovered to date is just a small percentage of the totality of possible states. Can you tell me is a phonon a particle in its own right or a photon in a particular state ?

We are not using the word states as to mean states of matter. We use the word state to mean a unique, in this case, energy configuration. The physical properties that differ between states could be the spin of the electrons, the electron orbitals, the type of bonds between atoms, etc.

My understanding of field theory is that all matter are fields. The particles, like electrons or photons, are simply the interactions of the fields. When the field interacts, it does so via a quanta of energy/momentum of the field. In the case of light, this quanta is the photon. Since we can only observe and measure via interactions, we can only see light directly as a photon, but we can still see the consequences of the field that gives rise to the photon. The photon is thus the excitation of the field (for light, the field is the scalar and vector potentials, the electric and magnetic fields are observables of the potentials).

So if I have a field of frequency f that is excited to n levels above the ground state, then this field has n photons. Whenever the field interacts, it does so through one of these photons. If the photon is absorbed, the field drops down to the n-1 energy state. That is, the field now has one photon less of energy.

 

[trogan]

We are not using the word states as to mean states of matter. We use the word state to mean a unique, in this case, energy configuration. The physical properties that differ between states could be the spin of the electrons, the electron orbitals, the type of bonds between atoms, etc.

My understanding of field theory is that all matter are fields. The particles, like electrons or photons, are simply the interactions of the fields. When the field interacts, it does so via a quanta of energy/momentum of the field. In the case of light, this quanta is the photon. Since we can only observe and measure via interactions, we can only see light directly as a photon, but we can still see the consequences of the field that gives rise to the photon. The photon is thus the excitation of the field (for light, the field is the scalar and vector potentials, the electric and magnetic fields are observables of the potentials).

So if I have a field of frequency f that is excited to n levels above the ground state, then this field has n photons. Whenever the field interacts, it does so through one of these photons. If the photon is absorbed, the field drops down to the n-1 energy state. That is, the field now has one photon less of energy.

Okayyy, I like it ! Can you recommend a book on quantum field theory that is up to date and high in concepts and low in maths

 

[Born2bwire]

Okayyy, I like it ! Can you recommend a book on quantum field theory that is up to date and high in concepts and low in maths

Not really. Quantum field theory at my university was a graduate level course that had two graduate level quantum mechanics courses as prerequisites (so two graduate and two undergraduate courses on quantum mechanics were the prerequisites for the field theory course). You will be very hard pressed to find a book that was conceptual in nature. The closest I can think of is Feynman's QED which was written for laymen but it does not delve very deeply at all into QED or field theory. The next best thing I can think of is Zee's "Quantum Field Theory in a Nutshell." The first chapter or two may be comprehensible, but he gains simplicity at the cost of deep understanding. He introduces the equations and chapters almost haphazardly because it would be too time consuming and difficult (his aim was to make just a general QFT textbook to act as a general introduction prior to a true QFT course) to explain where they came from exactly or the mathematical rigor behind them. Feynman's Path Integral text is good but it was a single run print in the 60's and can be hard to find. In addition, as the title portion suggests, it is about his path formulation more so than quantum field theory.

EDIT: Art Hobson had a few papers discussing using a few quantum field theory concepts to help explain the wave nature of matter. The same goes for light and photons so it may help as further clarifications of the brief ramblings I introduced earlier.

http://physics.uark.edu/hobson/pubs/05.03.AJP.pdf
http://physics.uark.edu/hobson/pubs/07.02.TPT.pdf

 

[trogan]

Not really. Quantum field theory at my university was a graduate level course that had two graduate level quantum mechanics courses as prerequisites (so two graduate and two undergraduate courses on quantum mechanics were the prerequisites for the field theory course). You will be very hard pressed to find a book that was conceptual in nature. The closest I can think of is Feynman's QED which was written for laymen but it does not delve very deeply at all into QED or field theory. The next best thing I can think of is Zee's "Quantum Field Theory in a Nutshell." The first chapter or two may be comprehensible, but he gains simplicity at the cost of deep understanding. He introduces the equations and chapters almost haphazardly because it would be too time consuming and difficult (his aim was to make just a general QFT textbook to act as a general introduction prior to a true QFT course) to explain where they came from exactly or the mathematical rigor behind them. Feynman's Path Integral text is good but it was a single run print in the 60's and can be hard to find. In addition, as the title portion suggests, it is about his path formulation more so than quantum field theory.

EDIT: Art Hobson had a few papers discussing using a few quantum field theory concepts to help explain the wave nature of matter. The same goes for light and photons so it may help as further clarifications of the brief ramblings I introduced earlier.

http://physics.uark.edu/hobson/pubs/05.03.AJP.pdf
http://physics.uark.edu/hobson/pubs/07.02.TPT.pdf

k, thanks. I have a book called "The Light Fantastic A Modern Introduction to Classical and Quantum Optics" but not a mention in it of Quantum Field Theory.

 

[obing]

for you first question :-


speed is a scalar quantities so direction of light at a small displacement~~ acceleration can be ignored (pointless) this should be valid for stationary

and for body absorbing light " read black body radiation" (for extra coverage)

as per Albert. e speed of light is constant "C" AND does not change in any frame of refrence

 

[obing]

Why does it travel in a particular direction and what determines this ?

consider a light source in a universe and a planet 1/2 ly behind it

then the direction of light wrt planet can be determined by cartesian 2d graph (basic)

relative to any object other objects direction.speed can be determined

without either one its constant ...! eg :- consider 1 lightsource in an empty universe the light / em field created by it looks constant

and expanding universe * can be held account as a frame of refrence for what's going on on the surface* of it (lol ...just weired idea)

thanks ...negative as well as positive critism is always welcomed ;)

 

[trogan]

Not really. Quantum field theory at my university was a graduate level course that had two graduate level quantum mechanics courses as prerequisites (so two graduate and two undergraduate courses on quantum mechanics were the prerequisites for the field theory course). You will be very hard pressed to find a book that was conceptual in nature. The closest I can think of is Feynman's QED which was written for laymen but it does not delve very deeply at all into QED or field theory. The next best thing I can think of is Zee's "Quantum Field Theory in a Nutshell." The first chapter or two may be comprehensible, but he gains simplicity at the cost of deep understanding. He introduces the equations and chapters almost haphazardly because it would be too time consuming and difficult (his aim was to make just a general QFT textbook to act as a general introduction prior to a true QFT course) to explain where they came from exactly or the mathematical rigor behind them. Feynman's Path Integral text is good but it was a single run print in the 60's and can be hard to find. In addition, as the title portion suggests, it is about his path formulation more so than quantum field theory.

EDIT: Art Hobson had a few papers discussing using a few quantum field theory concepts to help explain the wave nature of matter. The same goes for light and photons so it may help as further clarifications of the brief ramblings I introduced earlier.

http://physics.uark.edu/hobson/pubs/05.03.AJP.pdf
http://physics.uark.edu/hobson/pubs/07.02.TPT.pdf

What I cannot find on the internet are animations that illustrate quantum theory. It seems to me that a picture (or even better a video) in this case is better than a million words. And most of the writers on quantum theory lack clarity. Art Hobson is better than most yet without illustrations his work is also lacking clarity. I totally agree with what he is proposing though. The wave/particle duality proposition was always going to be replaced by something that actually made sense.

Are you aware of any software that animates QFT principles ? Would there be a demand for it ?

 

[Born2bwire]

What I cannot find on the internet are animations that illustrate quantum theory. It seems to me that a picture (or even better a video) in this case is better than a million words. And most of the writers on quantum theory lack clarity. Art Hobson is better than most yet without illustrations his work is also lacking clarity. I totally agree with what he is proposing though. The wave/particle duality proposition was always going to be replaced by something that actually made sense.

Are you aware of any software that animates QFT principles ? Would there be a demand for it ?

Quantum mechanics really doesn't directly describe any physical process. The physical observations are described by processing the mathematics. The fields that we are talking about in quantum field theory or the wave functions in quantum mechanics are not physical quantities that we can directly observe and measure. As such, there isn't really anything we can do in terms of visuals. Quantum field theory does have a visualization called Feynman diagrams. But these diagrams are not true physical processes, but rather they are a visual tool that aids in the mathematics. Feyman gives a vague visualization of his path integral in his QED book but it isn't very clear to a reader who doesn't know the mathematics of the path integral in the first place (Feynman discusses the phase variation by using a clock).

 

[trogan]

Quantum mechanics really doesn't directly describe any physical process. The physical observations are described by processing the mathematics. The fields that we are talking about in quantum field theory or the wave functions in quantum mechanics are not physical quantities that we can directly observe and measure. As such, there isn't really anything we can do in terms of visuals. Quantum field theory does have a visualization called Feynman diagrams. But these diagrams are not true physical processes, but rather they are a visual tool that aids in the mathematics. Feyman gives a vague visualization of his path integral in his QED book but it isn't very clear to a reader who doesn't know the mathematics of the path integral in the first place (Feynman discusses the phase variation by using a clock).

so you have no mental picture of quantum fields or their interactions ?

You might try https://www.amazon.com/dp/0387989293/?tag=pfamazon01-20

or http://phys.educ.ksu.edu/vqm/index.html"

The big problem I have with most of physics is that there seems to be a fixation with describing things mathematically. No only does this give rise to problems of visualising systems, mathematics does not deal with complexity well and quantum systems seem to be hideously complex. The only way to fly in my opinion is with computer simulations of quantum fields using advanced state machine concepts.

 

[Dale]

Ok, so I guess a photon is destroyed when it is absorbed by an electron. And the electron has the capability to create it anew when it emits a photon. So it would seem light is not really slowed down by a transparant medium. It is constantly being destroyed and recreated by electrons and in between always travels at c.

I wonder about the supposed impossibility of stopping light when I read articles like the followinghttp://www.wired.com/science/discoveries/magazine/15-11/st_alphageek"

As I mentioned above, I was being sloppy. I was speaking specifically about light in vacuum. You really need to use QED to describe the propagation of photons through a transparent medium at an atomic level, or through a Bose-Einstein condensate at even a macroscopic level. To my knowledge all of the experimental results to date have validated QED.

 

[SystemTheory]

The big problem I have with most of physics is that there seems to be a fixation with describing things mathematically. No only does this give rise to problems of visualising systems, mathematics does not deal with complexity well and quantum systems seem to be hideously complex. The only way to fly in my opinion is with computer simulations of quantum fields using advanced state machine concepts.

Video game developers spend millions (billions) on visualization models with accurate physics engines, and yet we have no major effort to animate concepts of physics. However I am fairly confident that smarter state machines will operate more like our brain, and therefore, machines will not rid physics of the need for math. The machine would either run a math model, or it would adapt to form its own models, and then we'll be back to the challenge of having to question the authority of a human-like expert machine.

 

[ZapperZ]

Video game developers spend millions (billions) on visualization models with accurate physics engines, and yet we have no major effort to animate concepts of physics. However I am fairly confident that smarter state machines will operate more like our brain, and therefore, machines will not rid physics of the need for math. The machine would either run a math model, or it would adapt to form its own models, and then we'll be back to the challenge of having to question the authority of a human-like expert machine.

This is totally false!

For example, what do you think are all those monte carlo simulations being done for numerous systems? While the LHC is down, there were numerous simulations on possible interactions, background, etc.. etc. I can show you many simulations of band structure calculations, etc.. etc. In fact, look at this week's http://physics.aps.org/articles/v2/108" , one such model calculations were done for a topological insulator! Or look up accelerator physics where before any structure is built, we simulate the dynamics or fields within the structure FIRST.

So yes, there are mathematical simulations being done ALL THE TIME! It may not be something you understand, but it is definitely done!

Zz.

 

[chroot]

The big problem I have with most of physics is that there seems to be a fixation with describing things mathematically.

Your "problem" is a common one. Most people naturally wish to make sense of the subatomic world by using concepts that they understand from the macroscopic world. You're familiar with billiard balls and pendulums, and you naturally want those concepts to apply universally -- but they don't. A vast amount of evidence -- compiled by millions of people over hundreds of years of study -- indicates that the behavior of very small things differs from the behavior of large things. If you apply macroscopic concepts to microscopic experiments, you get the wrong answers, after all.

Consider a box full of gas. It has familiar macroscopic properties like pressure and temperature. You know what these properties mean because you have experienced them directly with your senses. The gas is actually composed of a great number of very small constituent particles, though, and you'll find it impossible to think rigorously about the "pressure" of a single particle, or the "temperature" of just one atom. The macroscopic concepts just don't apply anymore. Instead, you'll find a whole new set of (perhaps surprising) microscopic phenomena, but the beauty is this: if you take the average of these microscopic phenomena, in the limit of a large number of particles, you will recover the original, higher-level concepts of pressure and temperature.

This is how science works. You can understand a system (a box of gas) from several different levels of abstraction, but they always dovetail together. The more fundamental levels always "blur" together and become the higher levels of abstraction. Physicists understand a box of gas at many different levels of abstraction: the macroscopic concepts of temperature and pressure rest upon the behavior of many billiard-ball like particles (statistical mechanics), and the particles themselves are composed of smaller subatomic particles, which are themselves described by quantum mechanics, and so on down the ladder.

The idea of a photon "being born" at c, never needing to accelerate, would indeed be a bizarre macroscopic concept, but there's no reason why it cannot be a perfectly acceptable (and complete!) microscopic concept. In the microscopic realm, particles simply do what particles do, even if those behaviors would not be physically possible for macroscopic objects.

You can also stretch some macroscopic concepts into analogies. When you drop a golf ball into a pool of water, the ripples do not "accelerate" from zero speed. They begin moving the instant they are created. In fact, their "creation" and "acceleration" are all tied up together in one movement, that of the ball through the water. It's important to recognize that these are analogies, though, and may have limitations.

It's entirely possible that the subatomic world is made up of little point masses that emit photons that appear instantaneously and disappear instantaneously. You might not like the answer, but you cannot invalidate the explanation by disliking it.

The only way to fly in my opinion is with computer simulations of quantum fields using advanced state machine concepts.

Scientific computation -- the simulation of physical behavior with computers -- is the world's largest use of computer power. Millions and millions of people spend their entire careers developing and running computer simulations. An absolutely astounding amount of our current scientific understanding was made possible by computer simulations. Your opinion is shared by, well, just about everyone.

- Warren

 

[SystemTheory]

This is totally false!

Which part of what I wrote is totally false? That there is no major effort to visualize physics? I meant that in mainstream education we do not animate the physics concepts, by the way, instead society spends money developing video games. I did not mean to imply that there are no animations of physical systems in engineering and expert development tools, since obviously, there are such animations.

So yes, there are mathematical simulations being done ALL THE TIME! It may not be something you understand, but it is definitely done!

Zz.

Notice I said a machine will either run a math model (monte carlo, etc), or it will operate like an internally adaptive knowledge filter and we will not have access to the math model. Thus the computer will either not eliminate the need for a math model, or if it does, it introduces a question of confidence in the solutions generated.

 

[trogan]

This is totally false!

For example, what do you think are all those monte carlo simulations being done for numerous systems? While the LHC is down, there were numerous simulations on possible interactions, background, etc.. etc. I can show you many simulations of band structure calculations, etc.. etc. In fact, look at this week's http://physics.aps.org/articles/v2/108" , one such model calculations were done for a topological insulator! Or look up accelerator physics where before any structure is built, we simulate the dynamics or fields within the structure FIRST.

So yes, there are mathematical simulations being done ALL THE TIME! It may not be something you understand, but it is definitely done!

Zz.

thanks ... the one I am particularly after is a traveling electron generating an electromagnetic field. I have looked high and wide on the internet and cannot find such a beast. In fact simulations of any kind regarding quantum physics are as rare as hen's teeth. Or maybe I need to know where to look ? I can find illustrations of Maxwell's equations but these don't give me a picture of what is actually happening in space.

And most, if not all, books I have read on quantum physics (and I have read heaps) spend 99% of their length trying to describe difficult concepts that are much better described in illustrations, and in particular illustrations based in time.

 

[trogan]

This is totally false!

For example, what do you think are all those monte carlo simulations being done for numerous systems? While the LHC is down, there were numerous simulations on possible interactions, background, etc.. etc. I can show you many simulations of band structure calculations, etc.. etc. In fact, look at this week's http://physics.aps.org/articles/v2/108" , one such model calculations were done for a topological insulator! Or look up accelerator physics where before any structure is built, we simulate the dynamics or fields within the structure FIRST.

So yes, there are mathematical simulations being done ALL THE TIME! It may not be something you understand, but it is definitely done!

Zz.

thanks. I suspect most of the simulations you talk about are based totally on mathematics rather than state machines. Mathematics has no hope when it comes to simulating complex systems. True, it is used in state machines but only in transitions from one state to another (where no time is involved ... or a quantum "leap" if you like). The behaviour of a state machine is determined by states and events. A big problem is that a deep understand of state machines requires about 10 years of study/practice (on top of a firm grounding in computers) and that current state machine theory has a long way to go before it can adequately simulate certain types of systems (this is my area of research).

I am guessing that because most physicists are also mathematicians, that state machines are not "elegant" enough for them or that they don't really understand state machines.

Actually, it seems to me that the main reason for the lack of simulations in quantum physics is that we don't have a deep enough knowledge of reality to enable a state machine to truly model it. We seem to know a lot about effects but little about causes. For example do we know why a particular energy 3d shape is able to persist over time ? It seems to be likely to have to do with attraction and repulsion forces within the shape but as far as I know no one has pinpointed the exact mechanism. But even so, we can at least animate (vs simulate) what is happening. As an aside (I am probably being naive here) are not 3d shapes rather than waves a better way of describing quantum fields ?

 

[SystemTheory]

I am guessing that because most physicists are also mathematicians, that state machines are not "elegant" enough for them or that they don't really understand state machines.

If I properly recall the premise of The Dreaming Universe it is that the universe can be considered a quantum state machine and so can the human brain. This is why I mentioned the book above and the idea that model-free computing merely uses complexity to know complexity, such that state machine = human brain. Then machines will debate humans.

What connection is there between your research and the physical properties of light? Are you trying to build a quantum computer that runs calculations with minimal power and time?

 

[ZapperZ]

thanks ... the one I am particularly after is a traveling electron generating an electromagnetic field. I have looked high and wide on the internet and cannot find such a beast. In fact simulations of any kind regarding quantum physics are as rare as hen's teeth. Or maybe I need to know where to look ? I can find illustrations of Maxwell's equations but these don't give me a picture of what is actually happening in space.

And most, if not all, books I have read on quantum physics (and I have read heaps) spend 99% of their length trying to describe difficult concepts that are much better described in illustrations, and in particular illustrations based in time.

This is odd, because (i) this is a classical physics problem and (ii) how do you think we design all those synchrotron radiation facilities?

Zz.

 

[ZapperZ]

Which part of what I wrote is totally false? That there is no major effort to visualize physics? I meant that in mainstream education we do not animate the physics concepts, by the way, instead society spends money developing video games. I did not mean to imply that there are no animations of physical systems in engineering and expert development tools, since obviously, there are such animations.



Notice I said a machine will either run a math model (monte carlo, etc), or it will operate like an internally adaptive knowledge filter and we will not have access to the math model. Thus the computer will either not eliminate the need for a math model, or if it does, it introduces a question of confidence in the solutions generated.

1. There ARE visualization tools for physics concepts in education. See the http://phet.colorado.edu/index.php" project for example!

2. "Visualization" is way overblown in this case. I'm NOT saying they aren't important, but trying to visualize 6D phase space, for example, and drawing it in 3D (or 2D as is the case) is a futile attempt and are done only for "public relations" to those who have no clue of the physics.

3. People don't complain about such thing to musicians when they represents their music using music notes. They somehow don't get the idea that when physicists read mathematical equations, those equations can, in fact, give the "music".

Again, simulations and "visualizations" are used ALL THE TIME in physics. It may not be the type of simulations that you think, or what you get out of some silly video game, but it is done!

Zz.