0 Members and 1 Guest are viewing this topic.

The famous e=mc2 equation seems to imply that mass and energy are interchangeable. Most people have this view. However, most bosons in the standard model are massless but do contain energy. This seems to strongly refute the interchangeability theory. I have also read recently that e=mc2 is just a conversion of mass units into energy units. This makes just so much sense when you try and think where the weird "speed of light squared" fits into the picture. So it may be that the equation is all about concepts rather than reality. Also, can anyone tell me where I can obtain a picture of the standard model that contains how many quanta (these will be whole numbers) are present in each particle in the table? And also, how do I convert quanta into mass?

That equation only works for masses at rest with respect to you (the observer) and indicates the energy content of the mass of that object if you were to measure it at rest. However, you're right that a Boson has zero mass, so how can it have energy? Well, a zero-mass Boson can't be at rest! So this equation doesn't hold for moving particles. The correct form of the more general equation is:E^{2}=m^{2}c^{4}+p^{2}c^{2}where p is momentum. So a moving Boson can (and does) have momentum and therefore energy, even though its mass is zero.

momentum is not always defined as: p=m*v. In the case of a photon, p=h/λ.

3. You cannot even find the number of quanta of energy in a particle of which you know the energy, if you don't have other informations. For example, for the quanta of electromagnetic field (photons) you have, at least, to know also the frequency of the field.

Yes.Energy-mass-energy conversion is an everyday phenomenon. If a sufficiently energetic (> 1.02 MeV) photon interacts with a nucleus it can produce an electron-positron pair (1.8 x 10^-30 kg) which then self-annihilates to generate two 511 keV photons. This phenomenon is exploited in radionuclide imaging.

Quote from: JP on 03/06/2014 11:44:05That equation only works for masses at rest with respect to you (the observer) and indicates the energy content of the mass of that object if you were to measure it at rest. However, you're right that a Boson has zero mass, so how can it have energy? Well, a zero-mass Boson can't be at rest! So this equation doesn't hold for moving particles. The correct form of the more general equation is:E^{2}=m^{2}c^{4}+p^{2}c^{2}where p is momentum. So a moving Boson can (and does) have momentum and therefore energy, even though its mass is zero.Thx JP. Problem with this equation is that p is momentum which is mass * velocity and many bosons do not have mass.

Quote from: lightarrow on 03/06/2014 13:09:073. You cannot even find the number of quanta of energy in a particle of which you know the energy, if you don't have other informations. For example, for the quanta of electromagnetic field (photons) you have, at least, to know also the frequency of the field. Thx lightarrow. My reading of a quantum is that h equals energy times 1 second. The energy, e, in e=hf is energy per second. All quanta, no matter what their frequency contain h amount of energy in total. The frequency relates to the power of a quantum, i.e. how fast the h amount of energy is transferred. Energy is a constant but power varies.

Quote from: lightarrow on 03/06/2014 13:09:07In a computer, reality is basically the digits (0/1) that make up the memory and the ability to manipulate the memory. Computer languages translate concepts into digits. Reality appears to be made up of space, time and fields (energy being a property of a field) plus, maybe, a meta-field. Everything else seems to be some kind of an abstraction (concept) of these basic elements, much like a computer. Hope I am not making a fool of myself here:).

What do you think of the possibility that e=mc2 is just a units of mass to units of energy conversion?

The famous e=mc2 equation seems to imply that mass and energy are interchangeable.

Quote from: mxplxxx on 04/06/2014 06:58:30Quote from: lightarrow on 03/06/2014 13:09:073. You cannot even find the number of quanta of energy in a particle of which you know the energy, if you don't have other informations. For example, for the quanta of electromagnetic field (photons) you have, at least, to know also the frequency of the field. Thx lightarrow. My reading of a quantum is that h equals energy times 1 second. The energy, e, in e=hf is energy per second. All quanta, no matter what their frequency contain h amount of energy in total. The frequency relates to the power of a quantum, i.e. how fast the h amount of energy is transferred. Energy is a constant but power varies.I answer to what I have underlined of your post.No! First, h is not energy, is "action". Second, the quantum of energy in the EM field is h*f where f is the frequency, so the value of the quantum *does* depend on its field frequency.Example: in a blue laser beam with (exact) wavelenght = 400 nm, every photon has an (exact) energy of 3.1 eV; in a red laser beam with (exact) wavelenght = 700 nm, every photon has an (exact) energy of 1.77 eV.--lightarrow

My reading of a quantum is that h equals energy times 1 second.

The energy, e, in e=hf is energy per second.

All quanta, no matter what their frequency contain h amount of energy in total.

The frequency relates to the power of a quantum, i.e. how fast the h amount of energy is transferred. Energy is a constant but power varies.

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.

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.

Not certain what this means but am sure if I was talking rubbish I would get many challenges.

Basically, the proposition being put by many physicists (and me) is that the quantum is one of energy, not action.

This proposition takes so much weirdness out of quantum mechanics. Lets face it, no one really knows how a quantum of action relates to reality.

Total nonsense. All physicists know what Planck's constant is and how it relates to reality.

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.

That is incorrect. That expression has units of energy, not power. It is the energy of one quantum. For example; if there is a photon whose frequency is f then the energy that the photon has is E = hf

Quote from: JP on 05/06/2014 10:54:51 My search for someone who can provide a definition of the Quantum of Action continues. I remain convinced that most of the physics community cannot provide this definition and so do not understand the basis of quantum physics (I may live to regret saying this!) .

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?

You are aware, I assume, that all quanta contain the same amount of action.

I am sorry to say that many physicists do not understand Planck's constant ..

- at least that is what I glean from my adventures on physics forums.

In fact, many physicists seem unaware of the Quantum of Action (this discussion of mine on Physics Forums makes this quite clear ...sorry, you cannot view external links. To see them, please REGISTER or LOGIN).

Quote from: PmbPhy on 04/06/2014 23:31:37I 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]

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.

Lets face it, no one really knows how a quantum of action relates to reality.

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 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.

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.

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?

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.

Quote from: mxplxxx on 08/06/2014 03:12:50I 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

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).

If action is obsolete then E=hf is also obsolete.

Thank you all so much for your time, and a very interesting thread.

Quote from: lightarrow on 08/06/2014 12:22:34Quote from: mxplxxx on 08/06/2014 03:12:50I 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?--lightarrowHi 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.

Returning to my original question, E (kg⋅m^{2}/s^{2}) = 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?

Because (and Einstein exploited this fact in GR) gravitational mass and inertial mass are the same thing.