Stefan Ram

2023-09-23 21:08:36 UTC

I prefer to learn from books. But videos have two advantages: One

can watch/listen to them while doing household chores, and one also

learns the correct English pronunciation of the technical terms.

So I listened to some videos of QFT lectures by Prof. Susskind.

However, after about three videos so far, I am rather disappointed.

I have the impression that Susskind deliberately wants to

counteract all too flowery gobbledygook with a "don't talk, but

calculate" approach. I have always found such an approach absurd

in physics, but especially devastating in teaching. He does some

math, "We put this in here, and then we get this," "I'm not going

to say why, I'm just going to do it this way," and then he says,

"And this is the simplest example of a quantum field." (these are

all not literal quotations). He doesn't explain what a "quantum

field" is supposed to be. This doesn't seem very educational to me.

As an example of an approach that I like (at least according to the

few pages I have read so far), I would like to mention "Quantum Field

Theory" by Mark Srednicki (which is a written text, not a video).

He first explains that it is about combining quantum mechanics and

relativity. In order to do this, space and time must be treated

"on an equal footing at the outset". In quantum theory, time is a

label (parameter), location is an operator. So to treat them equally,

one can either treat location as a label, or one can treat time as

an operator, says Srednicki. Since the second is a bit complicated

(Srednicki says it would lead to string theory), Srednicki follows

the way to make the location a label. Each location x is associated

with an operator phi(x). And this is a quantum field.

So Srednicki first explains what requirements a quantum field

should satisfy and why, and then he shows how these requirements

can be satisfied, so that one can grasp the concepts. Susskind

lacks such an explanation (though I have not seen all the

videos in the series, so I may be missing something).

[[Mod. note -- It would be useful to have references to the specific

videos and books under discussion. -- jt]]

can watch/listen to them while doing household chores, and one also

learns the correct English pronunciation of the technical terms.

So I listened to some videos of QFT lectures by Prof. Susskind.

However, after about three videos so far, I am rather disappointed.

I have the impression that Susskind deliberately wants to

counteract all too flowery gobbledygook with a "don't talk, but

calculate" approach. I have always found such an approach absurd

in physics, but especially devastating in teaching. He does some

math, "We put this in here, and then we get this," "I'm not going

to say why, I'm just going to do it this way," and then he says,

"And this is the simplest example of a quantum field." (these are

all not literal quotations). He doesn't explain what a "quantum

field" is supposed to be. This doesn't seem very educational to me.

As an example of an approach that I like (at least according to the

few pages I have read so far), I would like to mention "Quantum Field

Theory" by Mark Srednicki (which is a written text, not a video).

He first explains that it is about combining quantum mechanics and

relativity. In order to do this, space and time must be treated

"on an equal footing at the outset". In quantum theory, time is a

label (parameter), location is an operator. So to treat them equally,

one can either treat location as a label, or one can treat time as

an operator, says Srednicki. Since the second is a bit complicated

(Srednicki says it would lead to string theory), Srednicki follows

the way to make the location a label. Each location x is associated

with an operator phi(x). And this is a quantum field.

So Srednicki first explains what requirements a quantum field

should satisfy and why, and then he shows how these requirements

can be satisfied, so that one can grasp the concepts. Susskind

lacks such an explanation (though I have not seen all the

videos in the series, so I may be missing something).

[[Mod. note -- It would be useful to have references to the specific

videos and books under discussion. -- jt]]