Common Misconceptions in Physics II

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Mar 2019
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cosmos
math vs physics

@dragon:
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What I want you to answer is your own question:
"Okay, I pretty much understand what you are talking about when you say "projections." It's pretty standard in Linear Algebra and stuff."
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What render space scale in projective geometry?
Human/math?
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thank you.
 

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topsquark

Forum Staff
Apr 2008
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On the dance floor, baby!
This is not a "Common Misconception." Please keep the speculation to a minum in this thread. Again, if you wish to have a conversation then we'll have to go further than this. I suppose I could allow a new thread but it would have to be in the Lounge Forum. And no more lewd pictures.

-Dan
 
Mar 2019
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speculation? or dictation?

@dragon:
Oh? Can you choose an answer in my first post in this thread?
 
Mar 2019
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freedom vs lewd

@dragon:
"...I suppose I could allow a new thread but it would have to be in the Lounge Forum"
That is your freedom.
"...And no more lewd pictures."
In the Chinese-English dictionary, even a simple English word would have several explainations. What's the standard for "lewd"? For this reason, I attached a picture for judgement...?
 

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Mar 2019
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analysis of answer

While such question as that one in my first post in this thread should not appear in test paper, it's an interesting question in physics.
When someone choose answer A, he is appling the vector calculation rule. it hints that the superposition of speed principle might be applicable to light. But the MM experiment demonstrates it's not.
 
Mar 2019
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cosmos
biggest misconcept

"...Most of Introductory level QM deals with Linear Algebra at its base concepts. Along with that concept comes "linear superposition," which means that we can simply add the wavefunctions as they move with respect to each other.

No, waves cannot be considered to be a sum of particle states.

This is exactly what I mean. You need more information to talk about QM. I could make a list if you like. I'd suggest starting with Linear Algebra.

What I've seen of X4 is that it illuminates nothing but obscures the structure that is there. (And in QM we don't need more complexities!)"
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The biggest misconcept is: math superior to physics
 

topsquark

Forum Staff
Apr 2008
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On the dance floor, baby!
"...Most of Introductory level QM deals with Linear Algebra at its base concepts. Along with that concept comes "linear superposition," which means that we can simply add the wavefunctions as they move with respect to each other.

No, waves cannot be considered to be a sum of particle states.

This is exactly what I mean. You need more information to talk about QM. I could make a list if you like. I'd suggest starting with Linear Algebra.

What I've seen of X4 is that it illuminates nothing but obscures the structure that is there. (And in QM we don't need more complexities!)"
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The biggest misconcept is: math superior to physics
If you have waves that obey the superposition principle then QM is greatly simplified. And many of the waves we observe are, to a large degree, linear. However, it is true that much of Physics does tend to work with linear waves because the Math of non-linear behavior is much more complicated. In that sense Physicists are a bit blind when it comes to non-linear behavior.

Of course we need to have more information to talk about QM. If we could find a method to understand everything (or at least a lot of) about QFTs then we'd be in a much better situation.

I have a tendance to joke about Physics being better than Math but when it comes down to it Math is the major tool that Physics uses to understand what is going on (at least from the standpoint of Theoretical Physics, which is primarily what I do.)

-Dan
 
Jun 2016
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England
There is nothing "wrong" with maths, and it is the best (perhaps the only) way of describing many phenomena in physics.

However some people become carried away by the elegance or "beauty" of the mathematical model,
possibly to the point of missing the "truth" of the underlying reality being described.

As an analogy,
I have read some books where the language was nuanced, poetic and lyrical.
I could marvel in shear admiration of the clever interplay of the words.
But the actual story being told was totally rubbish.
 
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Mar 2019
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rubbish mirrors rubbish

I don't like to say rubbish words. I like to do something substantial and creative step by step.
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Analysis of answer B:
The released photon is in the state of X4 =∞.
Next, let’s see what the result will be.
X = X4*χ=∞*χ= ∞
So, the four dimension spacial coordinate in the world of the released photon is X ≡∞
That is to say any point of three dimensional space is the same from the view of the released photon.
The three dimensional space is ineffective in another word. Vetcor does not applicable in the world of released photon. So, answer C is actually the best one. But we can try to analysis answer B for spirit of exploration. Namely the component of light speed is the same c in all directions. There is a natural phenomenon: the speed of propogation of spherical light is the same c in all directions.
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(Don't make misconcept in the attached picture...it's navel. haha...)
 

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Mar 2019
774
40
cosmos
math vs physics

"...Of course we need to have more information to talk about QM."
It's true. Seems not limited to QM alone. If Einstein got that exact "more information", I think he would not have so much rows with QM physist in his last days of life. That's history.
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"...If we could find a method to understand everything (or at least a lot of) about QFTs then we'd be in a much better situation."
I think "at least a lot of" is more appropriate than "everything".
There are a lot of "storys" such as QFT in modern physics. Almost one suit of theory is needed or one model is established to explain one phenomenon. But cosmos is just only one. But I don't think any one of the storys should be dubbed the word "******". They are all endevours of human to try to understand nature. High price is true in history of exploration.
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"...I have a tendance to joke about Physics being better than Math ". "but when it comes down to it Math is the major tool that Physics uses to understand what is going on (at least from the standpoint of Theoretical Physics, which is primarily what I do.)"
You have already know that "Math is the major tool that Physics uses to ...", why tend to "joke about Physics being better than Math "?
The question is that if the kind of math you use is capable of describing the the issues of phsics at your hand. I like to joke about that if plane geometry can describe solid?
 

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