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Author Topic: Are mass and energy really interchangeable?  (Read 19969 times)

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #25 on: 05/06/2014 12:42:35 »
Interestingly, if we rewrite the e=hf equation as et=h then it can be seen that as we increase energy, time decreases and vice versa. And if we increase time, energy decreases and vice versa. It could be argued that time and energy are interchangeable, much like energy and mass.
 

Offline JP

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Re: Are mass and energy really interchangeable?
« Reply #26 on: 05/06/2014 12:51:23 »
No, because T=1/f, where T is period of oscillation, so as we increase period energy decreases and vice versa.
 

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #27 on: 05/06/2014 13:16:55 »
e=hf so h=e/f so h=e * 1/f so h=eT  what is wrong with my logic?
 

Offline JP

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Re: Are mass and energy really interchangeable?
« Reply #28 on: 05/06/2014 13:25:48 »
You said T was time, and it is not.  It is period of oscillation.
 

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #29 on: 05/06/2014 13:39:55 »
Period is time isn't it? I should have been more precise about the original equation. So h=eT and so it would appear in some sense energy and time are interchangeable. Given that this is happening inside a quantum, it seems to be a fundamental transformation. What about conservation of energy though? Energy cannot just vanish can it. So maybe the equation is flawed in some way? Hard to see unless e=hf itself is flawed in some way.
 

Offline JP

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Re: Are mass and energy really interchangeable?
« Reply #30 on: 05/06/2014 14:04:56 »
Period is not time.  Period is a measurement of the length of time it takes for the field to go through one full oscillation.  This oscillation is a physical process describing a fundamental property of the field.  This is important because if you change the value of period, you're describing a fundamentally different physical process-- a field with fundamentally different properties.

It therefore makes sense that ET=h, since if you change the field you're describing, it is natural that the energy of its quanta change as well.
 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #31 on: 05/06/2014 18:37:34 »
Quote from: mxplxxx
Hi PmbPhy. I was talking about the Quantum of Action. If you can define and explain this entity, then I take my hat off to you. Care to have a try?
Why? You already know what it is and what it means, donít you? Itís what most people call Planckís constant. In fact some texts, such as Principle of Modern Physics by Leighton refers to this constant on page 65 as Planckís quantum of action and is given the symbol h. In case you donít know your physics history and donít know why Planck define this term Iíll explain: There were problems in thermodynamics for which all attempts using classical physics failed to solve the problem. Planck was working on the problem of black body radiation. He was able to solve the problem theoretically by making a few assumptions, namely that the walls of the cavity inside a black body contained harmonic oscillators and that each oscillator could only radiate energy having the value E = nhf where n is a positive integer and f the frequency of the oscillator. In order for Planckís theory to fit the observed data Planckís constant has to have the value h = 6.6252x10^(-34)Js

Quote from: mxplxxx
You are aware, I assume, that all quanta contain the same amount of action.
Not only is that wrong but itís meaningless. Quanta such as a photon can never be said to ďcontainĒ action. Itís total nonsense to suggest such a thing

Quote from: mxplxxx
I am sorry to say that many physicists do not understand Planck's constant ..
Quite wrong. All physicists know what Planckís constant is. You donít know what youre talking about.

Quote from: mxplxxx
- at least that is what I glean from my adventures on physics forums.
Then you gleaned wrong. Worst case scenario Ėphysicists donít recall that Planckís constant used to sometimes be referred to as Planckís quantum of action. Thatís about it. However thatís merely history. Not physics. Or perhaps they donít know why Planckís constant is also called Planckís quantum of action. But certainly not what youíre claiming.

Quote from: mxplxxx
In fact, many physicists seem unaware of the Quantum of Action (this discussion of mine on Physics Forums makes this quite clear http://www.physicsforums.com/showthread.php?t=367434).
Thatís merely a name. A simple alternate term which hardly ever used. Not knowing this alternate terms means nothing other than people donít memorize dictionaries.
 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #32 on: 05/06/2014 18:40:24 »
I find that impossible to believe. If what you claim is true for "many" physicists then you should be able to name just one. Please do so.

Juliana Brooks Mortenson at [NO SPAMMY LINKS PLEASE]
You have to be kidding me!! There's nothing on that page but a companies website. Merely posting that URL in no way addresses my question
« Last Edit: 06/06/2014 09:40:34 by Georgia »
 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #33 on: 07/06/2014 00:00:17 »
Quote from: mxplxxx
Judging by the number of people in physics asking the meaning of e=hf, it is reasonable to ask if the equation is correct. Many in the physics community are deciding that it is not.
Iím still waiting for your reply. I also want to know who it is that youíre referring to when you speak of the Many in the physics community. Are you referring to actual professional physicists? First, letís be clear as to what a professional physicist is as the term is used by members of the profession. A professional physicist is a person who works at a job that requires special education in the various branches of sciences including physics, chemistry and math. That person may or may not get paid for their work as a physicist. So what proof do you have that that the majority of such people are as confused as you claim they are?

Quote from: mxplxxx
I explain why in http://www.thenakedscientists.com/forum/index.php?topic=41125.0. The post has been viewed by 1537 people and only one reply has been forthcoming.
So what? I canít blame them. Youíre all over the map with your accusations and from the posts youíve made itís clear that your understanding of quantum mechanics is seriously flawed. Itís quite possible that people may be ignoring you because they donít thing that youíd be able to understand the explanation that they give you.

Take Planckís constant as an example. In explained its origin above. I believe it was later on, after he defined it and after Einstein used it, that the synonym quantum of action was coined. There was a very good reason for it in the Old Quantum Theory described in Wikipedia at
http://en.wikipedia.org/wiki/Old_quantum_theory

Look at the first integral is known as a Phase integral (caution: the term phase integral, like so many other words in English, has other meanings). It has units of action. As you can see, the first integral in that page is the integral of pdq where p is the generalized momentum conjugate to the generalized coordinate q. Do you know physics well enough to know what these terms mean?

The action is probably different than youíre used to seeing it. Typically action is defined as the time integral of the Lagrangian which means that it has units of ďenergyĒ x ďtimeĒ, i.e. J*s. Recall that the units of Planckís constant also has units of action. If you sat down and worked out the units of the integral of p*dq youíd also see that it too has units of action. If we were to apply this to the hydrogen atom then weíd get the results known as the Wilson-Sommerfeld quantization rules. According to these rules, the phase integral of any variable over a complete cycle of its motion must be equal to an integer times Planckís constant. Thatís exactly why h is also referred to as the quantum of action. Since this is from the old quantum theory itís wrong and no longer used anymore. Thatís why nobody uses it.

Bohr came up with the idea that
(1) each electron in an atom revolves about the nucleus in a fixed orbit satisfying the condition that the angular momentum is an integral multiple of hbar == h/2*pi
(2) an electron does not radiate while occupying one of the quantized orbits but light s emitted or absorbed when an electron changes from one orbit to another.

So everything youíve said about quantum mechanics, Planckís constant h and the Quantum of Action is therefore wrong. All of what Iíve said can be found in the textbook Principles of Modern Physics by Robert B. Leighton, McGraw-Hill Book Company (1959) in chapter two.

Quote from: mxplxxx
Not certain what this means Ö.
Itís simple enough to find out what it means. Simply send a select number of members a PM asking them if they read it. When you find some of those who read it then ask them why they didnít respond. When people read what other people believe and see that itís all wrong experience has shown them that the people who post their beliefs rarely if ever, change them even after theyíve been corrected. More often than not they are unable to understand the corrections and then go ahead and claim its wrong. Iíve seen this a countless number of times. A very large number of physics enthusiasts learn what they know of physics from popular physics books on particular subjects. They rarely pick up an actual physics textbook such as the ones used in a college course. The reason most likely being that it requires a lot of math (algebra, geometry, trigonometry, calculus, etc), which they hated in high school and certainly donít want to experience as an adult. This results in a very poor foundation, which then causes all sorts of misunderstandings.

Quote from: mxplxxx
Öbut am sure if I was talking rubbish I would get many challenges.
Thereís absolutely no reason to believe that at all. Most people are likely very comfortable letting you believe whatever it is that you want to believe. People will only correct you when you attempt to explain something to someone else thatís wrong. For example; if you want to believe that the Earth is flat then all the power to you. However if someone comes here asking about how the shape of the Earth was discovered and you try to convince them that the surface of the Earth is flat then people will correct you very quickly.

Quote from: mxplxxx
Basically, the proposition being put by many physicists Ö
Please provide proof of this assertion.

Quote from: mxplxxx
(and me) is that the quantum is one of energy, not action.
Your poor understanding of quantum mechanics is causing you some problems now. You donít seem to know what the term quantum means. Please learn the correct definition of quantum and other terms such as [I[quantized[/i] at http://en.wikipedia.org/wiki/Quantum

Let me give you some examples of how one uses the term.

Example 1) A electron is a quantum of the charge on a Van de Graaff generator.

Example 2) An atom is a quantum of matter.

Example 3) A photon is a quantum of light.

Example 4) The states of a particle in a potential well are quantized.

Example 5) The z-component of the spin of any particle is quantized.

Quote
Lets face it, no one really knows how a quantum of action relates to reality.
This is quite a false statement and is based on your ignorance of quantum mechanics.

Note: By ignorance I merely mean lack of knowledge, and not anything like stupidity or a state of being unwise. I donít mean any disrespect by what Iíve talked about above.
 

Online alancalverd

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Re: Are mass and energy really interchangeable?
« Reply #34 on: 07/06/2014 10:31:14 »
I should point out that what's going on in situations like pair annihilation/production is that the form of the matter is what's being converted.

Tell me more! AFAIK a photon is not matter. We start with a quantum of energy, transform it through an intermediate phase of mass, and end up with two quanta of energy.
 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #35 on: 07/06/2014 16:40:17 »
Quote from: alancalverd
Tell me more! AFAIK a photon is not matter.
That depends on how you define the term matter. In his 1916 paper on general relativity Einstein defined it as follows
Quote
We make the distinction hereafter between "gravitational field" and "matter" in this way, that we denote everything but the gravitational field as "matter." Our use of the word therefore not only includes matter in the ordinary sense, but the electromagnetic field as well.
This appears in some texts publishedwithin that last 10-20 years as well such as some by the relativist Hans C. Ohanian.

This whole "converstion" thing can be phrased without using the term "matter." The invariant mass of a system of particles is given by

M_system = Sum m_i + Sum K_i/c^2

where m_i is the proper mass of the ith particle and K_i is the kinetic energy of the ith particle. Since the proper mass of a photon is zero the proper energy of a photon also zerp. Since the enery of any particle is the sum of its proper energy and kinetic energy it follows that the energy of a photon is all kinetic energy. Therefore part the mass of constituents has been coverted into energy. But it must be kept in mind that total mass and total energy remains the same in all reactions. Only the makeup of the system has changed.
 

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #36 on: 08/06/2014 03:12:50 »
I repeat what I have said about action. Energy comes in wave packets called quanta. All quanta expend the same amount of action when interacting - Planck's constant h. Action is the expenditure of energy per unit of time. This is given by the equation h=ET.
 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #37 on: 08/06/2014 05:14:24 »
Quote from: mxplxxx
I repeat what I have said about action. Energy comes in wave packets called quanta. All quanta expend the same amount of action when interacting - Planck's constant h. Action is the expenditure of energy per unit of time. This is given by the equation h=ET.
Why on Earth are you changing the subject to something that nobody cares about?

Let me recall for you what you asked of me and what you said the return would be
You asked the following question:
Quote from: mxplxxx
I was talking about the Quantum of Action. If you can define and explain this entity, then I take my hat off to you. Care to have a try?
I took the time and effort to explain exactly what you were looking for, ad this is what I get for my trouble, i.e. you igored it and stated some bogus  nonsense rooted in your ignorance in physics? 

BTW - I asked you where and/or how you learned physics but you never answered. Why is that? Explaining this to me will help me help you learn

I explained why most people arenít familiar with it, i.e. it's from the old, and thus invalid, quantum theory and its probably no longer taught even in undergraduate quantum mechanics courses. I know it because I've been physicist for well over 20 years now and studying physics for 30 years now. I learned it in my undergraduate quantum mechanics course.


and I was kind enough to take the time to answer it. Youíve been looking for that answer for sometime now. The least you could do is acknowledge that you now have your answer and why you were wrong. However we have no expectations of you thanking us when we help you. But this response is clearly your attempt to get around not acknowledging that you have proof of why you made a serious mistake like that.

You should have listened to JP. Heís very smart and very knowledgeable person. Better yet, you should learn physics, the right way this time. Then learn how to engage in a scientific discussion. In that kind of discussion you donít simply ignore what the other person is saying. You either present an argument in which you demonstrate that their wrong or you admit that youíre wrong. Of if youíre the type who is too arrogant to admit to their mistakes then gracefully bow out of the argument. Under no condition do you instead change the subject to something totally irrelevant where nobody cares about the subject, like you just did here.

However you learned it up until now, it led you to have many misconceptions. One of these misconceptions has to do with your obsession with the term quantity of action. Even though I explained to you, and even showed you the Wiki page about the old quantum theory, you ignored me. We call it the Old Quantum Theory because (1) it predates modern orthodox quantum mechanics and (2) its not used anymore because it has major flaws in it (e.g. in the Bohr model an electron in the ground state has the value h/pi whereas in the correct theory, i.e. orthodox quantum mechanics, L = 0).

One of the major problems with it, which is not mentioned there, is that its derivation is based on classical trajectories. For example; in the Bohr theory the electron moves in circular orbits. In the Wilson-Sommerfeld theory the electrons can also move in elliptical orbits.

Another misconception you have is your statement Energy comes in wave packets called quanta which is wrong. Youíre thinking of particle ot energy. Particles are the real physical entities that experience the wave-particle duality. Energy is merely a mathematical concept related to whatís observed in nature. All we know about energy is that it comes in various forms and the sum of the various forms for a closed system remains constant in time, i.e. is conserved.

Youíre claim that All quanta expend the same amount of action when interacting - Planck's constant h is quite misguided. First off its based on action which comes from a wrong, outdated theory. However if, for example, youíre talking about a photon and are referring to the relation E = hf where h = Planckís constant, f = frequency of photon and E = energy of the photon and are claiming that all photons have the same energy, then youíre absolutely wrong. If youíre thinking about the old theory and are referring to Integral pdq= nh then youíre wrong there too.

You should have listened to JP. He knows what he's talking about.

In my next post I'll explain what E = hf means in excruciating detail
« Last Edit: 08/06/2014 06:11:07 by PmbPhy »
 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #38 on: 08/06/2014 07:03:16 »
Quote from: mxplxxx
All quanta expend the same amount of action when interacting - Planck's constant h. Action is the expenditure of energy per unit of time. This is given by the equation h=ET.
There's no such thing as expending action. Action is not a thing that exists in nature. The same is almost true about energy but with energy there is something corresponding to the mathematical bookkeeping concept that defines energy. So it's not all together un-meaningful to speak of expending energy but one has to be very clear about what one means when talking about it. But you're once again confusing period with time, thus once more ignoring what JP said. You're confusing time with period because they're related and have the same units.

Consider time to start with. We will set up a laboratory and in the laboratory we will set up a clock. On Jan. 1 at 12:00am 2015 we will set the clock to read zero. It reads the absolute value of time, in seconds(s), after the zeroing event and not the time of day like other typical clocks read. Let this value be ďtĒ. It represents the time that the clock reads. It represents the time parameter that appears in Maxwellís equations. Itís a constantly increasing number. If we might repeat an experiment starting at exactly the same time each day then when we start the experiment the clock will read the time it read yesterday plus 86,400 s.

In the lab we will have 3 sources of photons. Each source emits individual photons. One emits blue photons (wavelength= 720 nanometers), one emits red photons (wavelength = 440 nanometers) and the last source emits green photons (wavelength = 833 nanometers). There is a photo detector that detects the photons and reads out the energy of the photon. All the photon detectors are identical. The wavelengths I used for sources is merely representative of those colors. In reality there is an entire spectrum of red, green and blue light.

Each morning we launch a red photon from the red photon emitter to its corresponding detector and measure the energy of the photon. An hour later we repeat this experiment. An hour after that we do the same thing but with green photons and then repeat it. Finally we repeat the whole thing using blue photons. The value of ďtĒ keeps increasing at a constant rate since thatís what time does. However T will have one single value in the first set of experiments corresponding to the period of red photons. T will have an entirely different yet single, value in the second set of experiments and finally T has another value corresponding to blue. So you see, the ďperiodĒ of a photon as a very different meaning than time itself. In each experiment ďtĒ Ė time had a different value. However T = period had the same value in the first and second experiments. T had the same value in the third and fourth experiments. T had the same value in the fifth and sixth experiments.

It takes about the same time to emit each photon and about the same time to detect each source. The frequency of the photons shouldnít be taken too literally. All it means is that the phase of the photon changes as it propagates at the rate given by the frequency of the photon. The period of the photon is also not related to how long it takes to absorb the photon either. We donít even think of the period of the photon as the time it takes for the photon to pass a certain plain parallel to its direction of propagation. The frequency of a photon has the following meaning: It is the amount of time for the phase of the photon to change by the value of 2pi.

Now we look at the energy of each photon, E = hf.  Let L = wavelength, T = period, c = speed of light. We can derive expressions for how theyíre related by using the fact that they have their usual meaning when applied to electromagnetic waves and these relations remain the same when going back to quantum theory. Therefore

c = L/T = Lf  => f = c/L

E = hf = hc/L

h = 6.626 x 10^(-24) Js, c = 3.00 x 10^8 m/s

L_red = 440 nm, L_blue = 720 nm, L_green = 833 nm

hc = [6.626 x 10^(-24) Js][3.00 x 10^8 m/s] = 1.9878 x10^(-15) Jm

E_red = hc/L_red = 1.9878 x10^(-15) Jm /440 x 10^(-9) m
E_red = 4.518 x 10(-9) J

E_green = hc/L_green = 1.9878 x10^(-15) Jm /833 x 10^(-9) m
E_green = 2.254 x 10(-9) J

E_blue = hc/L_blue = 1.9878 x10^(-15) Jm /720 x 10^(-9) m
E_blue = 2.761 x 10(-9) J

The way youíre using E = h/T is all twisted since you keep misinterpreting what T is. And your obsession with ďquantum of actionĒ is just a waste of time since it originated from an old theory, one no longer in use. The reason itís a waste is because this old theory is old because itís wrong. No such action can be defined in modern quantum mechanics because the classical trajectories that itís defined relative to donít exist.
 

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #39 on: 08/06/2014 08:35:06 »
I do not have the time to reply to your copious posts. Pick your battles. I do not reply full-stop to people who come across as unfriendly and you most certainly do. I am only replying to your last post because you have toned down your language. I have studied quantum physics as a hobby for many, many years. I have university maths A & B qualifications. Also Computer Science. I am a software developer who specialises in State Machines. Also a degree-qualified life coach. I firmly believe physics has somewhat missed the boat by concentrating so much on mathematics in an attempt to explain reality. The purity of mathematics and the messy nature of reality do not go together well. Computer-based state-machine simulations (with, maybe, a mathematical core) are the only way to go, in my opinion, to explain reality. I study physics because it is fascinating and because I am trying to create an artificial reality based on state machines and the principles of physics. I am a world-class software developer who has a real talent for simplifying complex phenomena.

I try to learn physics based on concepts rather than mathematics. I can learn a concept in minutes whereas it may take me weeks to understand the mathematics that attempt to underpin the concept. Unfortunately physics seems to have few champions who can talk in conceptual rather than mathematical terms. Unfortunate, also, that physics is full of often competing theories that just don't make much sense in the big picture and don't explain the "how" of reality. Last time I heard there were about 10 string theories that do all an equally good job of explaining the standard model. If I were you, I would not hold onto your precious theories with any degree of certainty.

I all my copious research on quanta and my equally copious discussions in physics forums I have never found out that h is not a quantity of action (I am aware that action is the integral of energy over time by the way). I am aware that energy is a disturbance in a field and that this equates to a particle (the field makes a comeback!). I am also aware that there is one field for each type of particle. And that a field occupies all of space. This is remarkably like the class/object relationship in software development. I am aware of symmetry's role in force and totally agree with susy's prediction that there will be a type of fermion that corresponds to each type boson. 

Finally, I don't actually accept h as a unit of action. Rather that it is a unit of energy and that all quanta "contain" h amount of energy. But this has been discussed before in the post. Hopefull you have read these onedrive files https://onedrive.live.com/redir?resid=8147C9C160CC0049!9056&authkey=!AI7DhJ90MuZE08U&ithint=folder%2c.

I am a long, long way from being an expert on physics and try and make it clear that I am no expert when discussing it - not always successful in this!




 

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #40 on: 08/06/2014 10:01:20 »
Knew all this. Pretty basic stuff. I am not talking about photons. I am talking about energy. It comes in wave packets called quanta. All quanta "contain" a constant amount of action, h (joules.sec). This is the basis of quantum physics and is a most remarkable fact. If action is obsolete then E=hf is also obsolete. The equation h=ET (a version of E=hf) illustrates the nature of a quantum (T is the period of the wave packet). If h = 10, then ET can be e.g. 10*1, 5*2, 1*10 etc..  Increase the energy and you decrease the period. And vice versa. Since energy is present in all particles in the standard model, the particles are said to be quantized.

But I am repeating myself.

Thank you all so much for your time, and a very interesting thread.
« Last Edit: 08/06/2014 10:41:01 by mxplxxx »
 

Offline lightarrow

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Re: Are mass and energy really interchangeable?
« Reply #41 on: 08/06/2014 12:22:34 »
I repeat what I have said about action. Energy comes in wave packets called quanta. All quanta expend the same amount of action when interacting - Planck's constant h. Action is the expenditure of energy per unit of time. This is given by the equation h=ET.
Apart the concept of "expenditure of energy", which I don't know what it means, what I coloured red of your post is wrong: action is energy*time, not energy/time. You don't even know what "per unit time" means?

--
lightarrow
« Last Edit: 02/09/2014 16:45:25 by lightarrow »
 

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #42 on: 09/06/2014 01:17:43 »
I repeat what I have said about action. Energy comes in wave packets called quanta. All quanta expend the same amount of action when interacting - Planck's constant h. Action is the expenditure of energy per unit of time. This is given by the equation h=ET.
Apart the concept of "expenditure of energy", which I don't what it means, what I coloured red of your post is wrong: action is energy*time, not energy/time. You don't even know what "per unit time" means?

--
lightarrow
Hi lightarrow. I always try and enlighten when I criticise a post. "Action is energy*time" is not an explanation of action. It is like saying energy is mass*speed of light squared. What does energy*time actually mean in reality? Noone knows. Probably I should not have attempted to try to explain it, especially as I have previously argued in this post that h is better thought of as energy, not action. Time to wind up this thread I think.
 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #43 on: 09/06/2014 03:14:15 »
Quote from: chiralSPO
momentum is not always defined as: p=m*v. In the case of a photon, p=h/λ.
That is incorrect. You're confusing a definition with an equality. The expression p = mv defines mass m (as well as momentum p). To understand what that ,seemingly confusing, statement means please see Eq. (7) at
http://home.comcast.net/~peter.m.brown/sr/inertial_mass.htm

Basically one defines m such that mv is conserved.

The expression p=h/λ does not define momentum. It is merely a relationship/equality between the momentum of a photon and its wavelength. However this thread was about special relativity, not qauntum memechanics. The former is a classical theory whereas the later is not. However the mass of a photon is well known to be defined the same way as for all other particles. In terms of magnitudes p = mv so that the mass of the photon in terms of its momentum is m = p/v. Since v = c for a photon we have m = p/c. The relationship between a photons energy and its mass is E = pc so that p = E/c. The mass of the photon in terms of the photons energy is then m = (E/c)/c = E/c2.

When mass is defined as m = p/v its sometimes referred to as relativistic mass. For more on the mass of a photon please see
http://math.ucr.edu/home/baez/physics/ParticleAndNuclear/photon_mass.html

 

Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #44 on: 09/06/2014 05:45:48 »
Mxplxxx: Let me explain something before I continue. I used to post using the handle Pmb. Iíve been a member since July 2009, i.e. for five years now. Iíve posted over 1,800 posts which has earned me the title Hero Member. However, due to the lack of proper moderation there are few members here who the moderators permit to be rude and violate the forum rules. Since you canít quit this forum and I was too tempted to come back and attempt to forget those horrible people I changed my account so that I couldnít use it. I went away and created my own successful forum. The hosting company went out of business so until I recreate my forum Iíll be posting here. I miss helping people to much.

Iím in the unfortunate position of being disabled. I have chronic pain that has not only ruined my professional life but makes me impatient. I also get angry easily as a result of what the pain does to my mind. So if I appear to be impatient you now know why.

However youíre not acting in way that makes me wish to continue after this post. My experience of posting online over the last 20 years has shown me that when you ask then a direct question about their knowledge of physics, i.e. how they learned it, where they learned it, how long theyíve been studying it, etc. in perhaps 95% of the time people will act as if you never asked the question and ignore you. They then repeat all the same nonsense that already corrected as if you never said anything at all. I will not bother helping people as inconsiderate as that. And thatís what youíre doing. I clearly asked you about the source of your education and you ignored me. If youíre ashamed of it then I have no time for you. But in order to help you I must know it. How else am I to understand what explanation you will or wonít be able to understand? As far as I know, the way youíve chosen to handle explanations you canít grasp is to ignore it as if I never posted it and then go on like I never posted it. Also, how can I possibly know how to explain something to you when I donít know whether you can grasp it or not. E.g. you keep talking about action but I have no way to know whether you even know what action is and how itís used in physics. From your responses and comments about it you speak as if youíre totally clueless about what it is. For example, you keep talking as if particles can actually ďpossesĒ or ďcontainĒ action which is complete nonsense. Any physicist will tell you that someone who says things like that doesnít know what theyíre talking about.

I have no wish to be rude. In fact Iím actually quite a polite person in life off the Internet.
But since youíve chosen to ignore me then Iím going to place you in my ďblock senderĒ list. I simply canít see talking to someone whoís ignoring what I write. Especially since your claim that you were to take your hat off to me was clearly a lie. When I proved what you wanted me to you ignored me.

Quote from: mxplxxx
Knew all this. Pretty basic stuff. I am not talking about photons.
Correction. You were talking about the relationship E = hf = h/T and kept making incorrect assertions about it. You keep confusing T (period) with t(time) and thatís what I was talking about. I used an example to drive my point home and you canít use an example unless you chose a type of particle to use in the illustration for which E = hf. Since that expression works for photons and all free particles I used photons to make it easier since the frequency has a more direct meaning that anyone can understand. E.g. a statement like ďthe photon is blueĒ canít be applied to electrons.

Quote from: mxplxxx
I am talking about energy.
Not really. You keep confusing energy with particles.

Quote from: mxplxxx
It comes in wave packets called quanta.
This is where your confusion lies and I already explained why its wrong. Why did you ignore me? If youíre going to ignore what Iím telling you then thereís no reason for me to make any attempt to help you, is there? If you claim than Iím wrong then please make an attempt to demonstrate it. But please donít simply ignore my correction and repeat your mistake over and over again. Itís frustrating.

Quote from: mxplxxx
All quanta "contain" a constant amount of action, h (joules.sec).
So. Once again youíre ignoring me and repeating your mistake. Let me let you in on something. When you wrote If you can define and explain this entity, then I take my hat off to you. Care to have a try? I was kind of impressed. I thought Hmmm. Perhaps


w
Donít you understand how much that kind of exchange violates the very foundations of science?  Since you donít appear to understand that please read the definition of science defined by the American Physical Society which is online at
http://home.comcast.net/~peter.m.brown/ref/what_is_science.pdf

Quote from: mxplxxx
This is the basis of quantum physics and is a most remarkable fact.
That is incorrect. The basis of quantum mechanics is the postulates of quantum mechanics. Theyíre also online at
http://hyperphysics.phy-astr.gsu.edu/hbase/quantum/qm.html

Quote from: mxplxxx
If action is obsolete then E=hf is also obsolete.
You keep ignoring what youíre being told. h is not action like you keep claiming that it is. I keep telling you why thatís wrong and you keep ignoring that with all the other things Iím trying to explain to you. Do you understand how irritating that is?

Iíll explain it one last time and then Iíll never try to help you understand it again until you learn it.

h is defined as a constant which appears in many places in quantum mechanics. Most notably it appeared when quantum mechanics was first being discovered. The very first instance that it occurred was the place it was defined. I already explained this above, i.e.  by Max Planck in order to account for black body problem radiation. Planck conceived of a black body as being composed as a collection of harmonic oscillators. To each oscillator he assigned it energy of the form E = hf, where h is a constant determined by experiment, f took on a variety of values. Later on in 1905 Einstein published a paper for which he was awarded the Nobel Prize. It was on the photoelectric effect.

The photoelectric effect is defined as follows: when light falls on a metal surface electrons are sometimes given off. Such electrons are referred to as photoelectrons. They are no different than any other kind of electron. They have that name only because of the way they are emitted.  Prior to Einstein physicists envisioned electrons absorbing energy from electromagnetic waves. The electrons are imagined to being shaken by the electric field until it has enough kinetic energy to be emitted from the surface of the metal that the light is being shined on. In order to explain the experimental results Einstein postulated the existence of photons, i.e. Einstein postulated that light is quantized (the light exists in discrete amounts) in units which came to be given the name photon. According to Einsteinís photon concept the basic process is the absorption of a quantum of energy E = hf by an individual particle.

Later on it was shown that when the energy of any free particle is measured it has a value given by E = hf whether itís a photon, an electron, a pion, a neutrino, etc. The relationship E = hf is not a condition of quantinization. For a free particle the energy can have any value in a continuous spectrum of possible values. So be aware of making that mistake. As a counter example consider the two examples all quantum mechanics students must learn; a particle of mass m in (1) an infinite square well of width a and (2) an harmonic oscillator of natural angular frequency w. The values of energy are (let n be a positive integer, i.e. n = 1, 2, 3, Ö.)

Infinite square well) En =hbar kn2/2, where kn = n pi/a

Harmonic Oscillator) En = (n + Ĺ)hbar w

If youíre not careful then youíre going to confuse the E = hf as being the energy of any particle whatsoever. When you do that youíll be making a mistake.

For a free particle E = hf is only one of a possibly continuous spectrum of values that the energy can have. E.g. a wave-packet for a free particle moving in one dimension is a superposition of plane waves, each of which has a different energy. Any function be represented as a Fourier series of sines and cosines so Fourier methods are used to create the superposition.

Quote from: mxplxxx
The equation h=ET (a version of E=hf) illustrates the nature of a quantum (T is the period of the wave packet).
Thatís not true. E = hf tells you absolutely nothing about a wave-packet. In fact if the only possible energy that the particle can have is E = hf then thereís no wave-packet at all. The wave is a plane wave. Only when you add up plane waves of different energies do you get a wave-packet.

Quote from: mxplxxx
Increase the energy and you decrease the period. And vice versa. Since energy is present in all particles in the standard model, the particles are said to be quantized.
Thatís quite wrong. Energy could always have been said to be present in particles dating back to the invention of kinetic energy. Classical mechanics gives the presence of energy in a particle. That in no way, shape or form makes the particles quantized.í

By the way, youíre misusing the term standard model. Thatís a widely misused term. The term Standard Model refers only to the theory of elementary particle physics. See http://en.wikipedia.org/wiki/Standard_Model

The only other use in physics is ďStandard Model of CosmologyĒ.


Quote from: mxplxxx
If action is obsolete then E=hf is also obsolete.
Good Lord! Where did you ever get that idea from? Itís only the ďquantization of actionĒ defined as Integral pdq = nh which is wrong. That in no way implies that E = hf is in anyway wrong. They have nothing to do with each other. This is what you get for being obsessed with ďquantum of actionĒ at the expense of all else. You too an alternate name for h and then claimed that since the motivation for that name is wrong then so to is all theories which motivated the term. Do you understand how illogical that deduction is? Wow! Its use in its current and original form has remained the same since it was created by Planck and Einstein. Donít confused  Wilson and Sommerfeldí s wrong turn as being the end all and be all of all of the quantum physics connected with Planckís constant h.


Quote from: mxplxxx
Thank you all so much for your time, and a very interesting thread.
What? No ďhatís offĒ yet for solving your problem, huh? False promises like that make people like me not want to help you ever again. This is about false statements, not arrogance of being under appreciated. Do what you promise to do or donít make any promises again.
 

Offline lightarrow

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Re: Are mass and energy really interchangeable?
« Reply #45 on: 09/06/2014 11:17:02 »
I repeat what I have said about action. Energy comes in wave packets called quanta. All quanta expend the same amount of action when interacting - Planck's constant h. Action is the expenditure of energy per unit of time. This is given by the equation h=ET.
Apart the concept of "expenditure of energy", which I don't what it means, what I coloured red of your post is wrong: action is energy*time, not energy/time. You don't even know what "per unit time" means?

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Hi lightarrow. I always try and enlighten when I criticise a post. "Action is energy*time" is not an explanation of action.
First, differently from you, I have never tried to provide such an explanation...
Second, I simply have corrected a mistake of you.
Third, if you want to discuss about physics concepts you have to use them properly...
Quote
It is like saying energy is mass*speed of light squared.
I wish you could! To define energy in general is not so simple, my friend!
Quote
What does energy*time actually mean in reality? Noone knows.
Tell it to Richard Feynman: he showed its meaning creating the "Path Integral" approach of quantum mechanics.
Quote
Probably I should not have attempted to try to explain it, especially as I have previously argued in this post that h is better thought of as energy, not action.
But you cannot give your personal meaning to physics concept which are already defined: they have *that* meaning and it's all. More so, you cannot do it with *physical quantities*: you cannot give the meaning of "energy" to a physical quantity which is instead "energy multiplied time", as you cannot, for example, give the meaning of "time" to a quantity which actually is a "lenght".

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Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #46 on: 10/06/2014 05:43:14 »
Returning to my original question, E (kg⋅m2/s2) = m (kg) c (m/s)2 looks remarkably like a units conversion to me! Is mass just concentrated energy? How can a unit that relies on gravity to define it come to represent energy at an atomic level?
« Last Edit: 10/06/2014 08:28:56 by mxplxxx »
 

Offline mxplxxx

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Re: Are mass and energy really interchangeable?
« Reply #47 on: 10/06/2014 08:48:44 »
For a much easier to understand approach to quantum physics, including equations that do not include Planck's constant, I recommend Jonathan Deutsch's Time's Dual Nature. I promise you it is a real game-changer.

http://www.amazon.com/Times-Dual-Nature-Common-Sense-Approach/dp/1453780998/ref=sr_1_1?s=books&ie=UTF8&qid=1402385625&sr=1-1&keywords=times+dual+nature
 

Offline lightarrow

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Re: Are mass and energy really interchangeable?
« Reply #48 on: 13/06/2014 18:20:01 »
Returning to my original question, E (kg⋅m2/s2) = m (kg) c (m/s)2 looks remarkably like a units conversion to me! Is mass just concentrated energy?
We had a lot of threads about mass in this forum.
You can define a system's mass as its energy (divided by c2) computed in a frame of reference where the system is still (= its total momentum is zero).But, as I and others have already written to you, if the system it's not still, its energy is not its mass multiplied c2.
Quote
How can a unit that relies on gravity to define it come to represent energy at an atomic level?
Because (and Einstein exploited this fact in GR) gravitational mass and inertial mass are the same thing.

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Offline PmbPhy

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Re: Are mass and energy really interchangeable?
« Reply #49 on: 14/06/2014 02:52:02 »
Quote from: lightarrow
Because (and Einstein exploited this fact in GR) gravitational mass and inertial mass are the same thing.
Letís be precise about this. Inertial mass, which Iíll label mi is not the same thing as gravitational mass. They are not identical, they are proportional.

What follows is how this is all explained in the physics literature, not merely something I came up with. Although it is something I highly agree with.

Einstein used the emperical fact that the inertial mass of an object is proportional to the bodies passive gravitational mass which Iíll label as mp. This is the mass on which gravity acts. If we let active gravitational mass as ma, which is the source of gravity. The gravitational force on the body due to the source, Fg, is then

Fg = Kmamp/r^2

where K is a constant of proportionality. Then since Fg = mai

a = (mp/mi)Kma/r^2

What Einstein exploited was the fact that there exists some constant c such that

mp = c*mi

a = (cmi/mi)Kma/r^2

a = cKma/r^2

Define the constant G = cK and call it the gravitational constant. Then

a = Gma/r^2
« Last Edit: 14/06/2014 03:13:13 by PmbPhy »
 

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Re: Are mass and energy really interchangeable?
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