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Author Topic: A poll on relativistic mass  (Read 18240 times)

Offline lightarrow

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Re: A poll on relativistic mass
« Reply #50 on: 06/12/2014 09:40:19 »
Alas, theoretical physics provides plenty of insights but no actual knowledge.
I (think to) understand what you mean, Alan, and I partially agree.
But remember that without any sort of theoretical framework, you can't even give any interpretation to experimental results...
So, actual knowledge is made of both experimental and theoretical physics, I believe.

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Offline JohnDuffield

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Re: A poll on relativistic mass
« Reply #51 on: 06/12/2014 15:05:43 »
Quote
...See "An Incorrect Application of Invariant Mass " in the webpage: http://home.comcast.net/~peter.m.brown/sr/invariant_mass.htm
The problem with posting such references is that nobody reads them and thus they never learn what the problems really are. They think that they know everything about the subject matter so they think they will learn nothing by reading any reference I post and therefore they remain ignorant of the problems.
People do read them. I've read this article, and I can say this: the mass of a particle is not invariant. It varies with gravitational potential. The kinetic energy of a falling particle comes from the mass-energy of that particle. Once the kinetic energy is dissipated you're left with a mass deficit. The mass is less than it was. It is not the same as it was and there is some magical mysterious negative energy thrown into the mix. There is now less positive energy, and less mass.
 

Offline yor_on

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Re: A poll on relativistic mass
« Reply #52 on: 06/12/2014 18:50:24 »
Ah well.
 

Offline PmbPhy

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Re: A poll on relativistic mass
« Reply #53 on: 06/12/2014 19:47:07 »
Quote from: alancalverd
I am an experimental physicist. I don't have a personality.

Add a "therefore", stir, and serve in any order you choose.
You said that you're a medical physicist, did you not? If so then you're not an since they're defined differently. A medical physicist does applied physics whereas an experimental physicist does experiments to test theories, i.e. they do experiments.

http://en.wikipedia.org/wiki/Medical_physics
Quote
Medical Physics is generally speaking the application of physics concepts, theories and methods to medicine or healthcare.

http://en.wikipedia.org/wiki/Experimental_physics
Quote
Experimental physics is the category of disciplines and sub-disciplines in the field of physics that are concerned with the observation of physical phenomena and experiments.

In my very humble opinion it was deceptive to say that you're an experimental physicist. I suggest that from now on you state the full truth, that you're a medical physicist, even if you do experiments! Einstein himself did a few experiments in his day. However that didn't make him an experimental physicist in addition to a theoretical physicist. I myself worked in a lab for a while calibrating the CCDs for the Chandra X-Ray observatory but just because I worked in a lab that didn't make me an experimental physicist. I didn't do experiments in that lab. The only experiments I've done were for my chemistry and physics courses.
« Last Edit: 06/12/2014 19:57:44 by PmbPhy »
 

Offline jeffreyH

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Re: A poll on relativistic mass
« Reply #54 on: 06/12/2014 22:30:03 »
Quote from: lightarrow
It was just *an example* of the fact that people usually (I'm not referring to you) have the incorrect idea that "energy is transformed in mass" or the other way round>>.
Now I can refer to you too...
Good point. It's so unfortunate that so many people make that mistake, regardless of how many articles are in the physics literature correcting that erroneous idea such as

Does nature convert mass into energy? by Ralph Baierlein, Am. J. Phys., 75(4), Apr. (2007)
http://home.comcast.net/~peter.m.brown/ref/baierlein.pdf

Thanks for that Pete. I will be saving a copy for future reference.
 

Offline jeffreyH

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Re: A poll on relativistic mass
« Reply #55 on: 06/12/2014 22:37:48 »
Quote
...See "An Incorrect Application of Invariant Mass " in the webpage: http://home.comcast.net/~peter.m.brown/sr/invariant_mass.htm
The problem with posting such references is that nobody reads them and thus they never learn what the problems really are. They think that they know everything about the subject matter so they think they will learn nothing by reading any reference I post and therefore they remain ignorant of the problems.
People do read them. I've read this article, and I can say this: the mass of a particle is not invariant. It varies with gravitational potential. The kinetic energy of a falling particle comes from the mass-energy of that particle. Once the kinetic energy is dissipated you're left with a mass deficit. The mass is less than it was. It is not the same as it was and there is some magical mysterious negative energy thrown into the mix. There is now less positive energy, and less mass.

Hang on a minute John. If that is your viewpoint then I think a mathematical proof is in order. I'm sorry but opinion just doesn't cut it. I've been down this path mathematically and my conclusion is that mass itself IS invariant.
 

Offline PmbPhy

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Re: A poll on relativistic mass
« Reply #56 on: 06/12/2014 23:32:47 »
Quote from: jeffreyH
I've been down this path mathematically and my conclusion is that mass itself IS invariant.
Hold on Jeff. If that is your viewpoint then I think a mathematical proof is in order for you too. Can you prove that mass is invariant other than choosing a definition in which it's invariant by definition. That's how everyone who presents such an argument does so. They either define the term mass as the value of mass as measured in the rest frame of the object/particle or they attempt to define it as the value of the particles 4-momentum (letting c = 1 for simplicity). Which do you do?

Let's once and for all resolve the problems with such a definition. Jeff: Please study the following page
http://home.comcast.net/~peter.m.brown/sr/invariant_mass.htm

very deeply so that you don't miss a trick. After you study that please study the section called "Definition of Mass" in my article at http://arxiv.org/abs/0709.0687

After you've studied those then you'll have an excellent understanding of these issues. Also let it be know that there is a difference between mass and energy in relativity. In GR the relativistic mass of a particle is defined as the time component of the particle's 4-momentum while the energy of the particle is defined as the time component of the particle's momentum 1-form. These two expressions do not equal each other. They're not even proportional. This is a fact that is all too often missed by most students studying relativity. It's one of the most important reasons why you can't say that relativistic mass and energy are the same thing.
 

Offline jeffreyH

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Re: A poll on relativistic mass
« Reply #57 on: 07/12/2014 00:53:05 »
Quote from: jeffreyH
I've been down this path mathematically and my conclusion is that mass itself IS invariant.
Hold on Jeff. If that is your viewpoint then I think a mathematical proof is in order for you too. Can you prove that mass is invariant other than choosing a definition in which it's invariant by definition. That's how everyone who presents such an argument does so. They either define the term mass as the value of mass as measured in the rest frame of the object/particle or they attempt to define it as the value of the particles 4-momentum (letting c = 1 for simplicity). Which do you do?

Let's once and for all resolve the problems with such a definition. Jeff: Please study the following page
http://home.comcast.net/~peter.m.brown/sr/invariant_mass.htm

very deeply so that you don't miss a trick. After you study that please study the section called "Definition of Mass" in my article at http://arxiv.org/abs/0709.0687

After you've studied those then you'll have an excellent understanding of these issues. Also let it be know that there is a difference between mass and energy in relativity. In GR the relativistic mass of a particle is defined as the time component of the particle's 4-momentum while the energy of the particle is defined as the time component of the particle's momentum 1-form. These two expressions do not equal each other. They're not even proportional. This is a fact that is all too often missed by most students studying relativity. It's one of the most important reasons why you can't say that relativistic mass and energy are the same thing.

It's the time component and the dilation effect that appears to produce more mass. It depends upon the interactions of the gravitational field with the elctromagnetic field. That is not easy to derive.
 

Offline jeffreyH

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Re: A poll on relativistic mass
« Reply #58 on: 07/12/2014 00:58:34 »
I am currently reading Lee Smolin's Three Roads to Quantum Gravity. When I have finished that I will get back to you.
 

Offline PmbPhy

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Re: A poll on relativistic mass
« Reply #59 on: 07/12/2014 01:22:36 »
I am currently reading Lee Smolin's Three Roads to Quantum Gravity. When I have finished that I will get back to you.
Okay. Let me know how that book is.
 

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Re: A poll on relativistic mass
« Reply #59 on: 07/12/2014 01:22:36 »

 

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