The Feynman File (2005)(discovermagazine.com)
discovermagazine.com
The Feynman File (2005)
http://discovermagazine.com/2005/mar/feynman-file#.UYajjbWPMnk
5 comments
A random note.
I first really understood special relativity from reading Feynman's lectures. A concept that he explained in there is that E = MC^2 really means that energy and mass are the same thing. A moving object weighs more because in addition to its own weight, it has the weight of its kinetic energy.
This is a very nice way to think about the issue. Unfortunately I discovered years later that nobody else thinks of it this way. Instead they think about mass as being rest mass, and that you turn from having energy to having mass and vice versa. Linguistically slightly different, but logically equivalent.
It still makes me sad that physics doesn't think about things in the simpler way that Feynman presented.
I first really understood special relativity from reading Feynman's lectures. A concept that he explained in there is that E = MC^2 really means that energy and mass are the same thing. A moving object weighs more because in addition to its own weight, it has the weight of its kinetic energy.
This is a very nice way to think about the issue. Unfortunately I discovered years later that nobody else thinks of it this way. Instead they think about mass as being rest mass, and that you turn from having energy to having mass and vice versa. Linguistically slightly different, but logically equivalent.
It still makes me sad that physics doesn't think about things in the simpler way that Feynman presented.
I can pretty much guarantee you Feynman didn't either -- when he was actually working with relativistic equations. The idea of a rest mass makes everything way, way simpler.
There was a Feynman quote in one of my physics texts that left a big impression on me -- basically saying that you shouldn't call yourself a physicist until you can understand the same physics using multiple models, gleaning insight from whichever is the most useful in context.
There was a Feynman quote in one of my physics texts that left a big impression on me -- basically saying that you shouldn't call yourself a physicist until you can understand the same physics using multiple models, gleaning insight from whichever is the most useful in context.
>you shouldn't call yourself a physicist until you can understand the same physics using multiple models
This applies to pretty much any field. Feynman was a great physicist from this point of view.
You want two line breaks in there.
Oh, I understand the practical advantages.
But I prefer it conceptually.
But I prefer it conceptually.
I have found "The concept of mass" by Lev Okun, (Physics Today, 1989) to be thought-provoking and informative on the subject. I return to it every time discussions of rest mass come up.
Physics Today link here: http://www.physicstoday.org/resource/1/phtoad/v42/i6/p31_s1?... Free PDF here: www.itep.ru/theor/persons/lab180/okun/em_3.pdf
Physics Today link here: http://www.physicstoday.org/resource/1/phtoad/v42/i6/p31_s1?... Free PDF here: www.itep.ru/theor/persons/lab180/okun/em_3.pdf
It still makes me sad that physics doesn't think about things in the simpler way that Feynman presented.
Two names for the same thing are redundant, so physicists decided to make a meaningful distinction:
By convention, 'mass' denotes the invariant but not conserved scalar quantity (rest mass/energy), whereas 'energy' denotes the non-invariant but conserved quantity, the time component of energy-momentum (total mass/energy).
Two names for the same thing are redundant, so physicists decided to make a meaningful distinction:
By convention, 'mass' denotes the invariant but not conserved scalar quantity (rest mass/energy), whereas 'energy' denotes the non-invariant but conserved quantity, the time component of energy-momentum (total mass/energy).
Interesting read, but if anyone is interested in more personal anecdotes like this, I suggest:
[1] http://www.amazon.com/Surely-Feynman-Adventures-Curious-Char...
[2]http://www.amazon.com/What-Care-Other-People-Think/dp/039332...
[1] http://www.amazon.com/Surely-Feynman-Adventures-Curious-Char...
[2]http://www.amazon.com/What-Care-Other-People-Think/dp/039332...
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http://www.amazon.com/gp/product/0465023711/
(The letters to family and Wolfram is also there.)
Another good one, in my opinion, is a rather raw portrait made from the vantage point of a student towards the end of Feynman's life. It's the unvarnished details that reveal the ordinariness and greatness of that physicist dude.
http://www.amazon.com/Feynmans-Rainbow-Search-Physics-Vintag...
I think Feynman really believed that anybody could become as (wise? accomplished? happy?) as he, and I think most books don't do justice to that dream of his, by making him out to be some kind of trickster god.