Penrose's "The Road to Reality" - Objection to Broken Electroweak Symmetry?

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In summary: AIn summary, Penrose seems to be critiquing the conventional perspective on electroweak symmetry, which is that it is unbroken. He seems to think that there is something strange about the way U(2) is taken as a gauge group, and he is hinting that there might be a problem with the Higgs mechanism due to this symmetry breaking.
  • #1
torquil
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Hi! This is for those who have read Penrose's "The Road to Reality" (btw, fantastic book).

In paragraph 25.8, on page 651, he writes something that I interpret as a critical remark regarding the spontaneous broken electroweak gauge symmetry.

Quote ( btw, he writes U(2) instead of the usual SU(2)xU(1) ):

"Also, there is the rather strange asymmetry between the roles of SU(3) and U(2) - in that SU(3) is taken to be exact, whereas U(2) is severely broken. Indeed, in my view, there does appear to be something strange about the particular way that U(2) is taken as a 'gauge group', which would seem to require an exact unbroken symmetry..."

Is he alluding to some problem regarding the EW theory that he does not write explictly? What does he mean by "... the particular way that U(2) is taken as a 'gauge group'"?

Anyone know/understand?

Best regards
Torquil
 
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  • #2
A gauge theory requires massless vector bosons. The vector bosons of weak interactions are massive (to the extent the 80 GeV is not negligible). By forgetting this, G, S, and W won the Nobel prize.
 
  • #3
Penrose doesn't like gauge symmetry breaking.

For Penrose's perspective, read the two sentences At the bottom of page 652 that begin with "The conventional perspective on electroweak ...," and then read sections 28.1, 28.2, and 28.3.
 
  • #4
George Jones said:
Penrose doesn't like gauge symmetry breaking.

For Penrose's perspective, read the two sentences At the bottom of page 652 that begin with "The conventional perspective on electroweak ...," and then read sections 28.1, 28.2, and 28.3.

Ok, thanks. I'm in chapter 27 at the moment, so I'll have it in the back of my head when I get to those sections.

Torquil
 
  • #5
clem said:
A gauge theory requires massless vector bosons. The vector bosons of weak interactions are massive (to the extent the 80 GeV is not negligible). By forgetting this, G, S, and W won the Nobel prize.

From wikipedia:

"In 1963 American physicist Sheldon Glashow proposed that the weak nuclear force and electricity and magnetism could arise from a partially unified electroweak theory. In 1967, Pakistani Abdus Salam and American Steven Weinberg independently revised Glashow's theory by having the masses for the W particle and Z particle arise through spontaneous symmetry breaking with the Higgs mechanism."

So maybe you could say that Glashow forgot it, then Salam and Weinberg remembered it later on :-)

Hopefully the LCH will be able to shed some light on the Higgs mechanism.

Torquil
 

1. What is "The Road to Reality" by Penrose?

"The Road to Reality" is a book written by physicist Sir Roger Penrose that attempts to explain the fundamental principles of the laws of physics and their relationship to mathematics. It covers a wide range of topics including quantum mechanics, relativity, and cosmology.

2. What is the concept of "broken electroweak symmetry"?

Broken electroweak symmetry is a theoretical concept in particle physics that explains the difference between the weak nuclear force and the electromagnetic force. It suggests that at high energies, these two forces were once unified, but as the universe cooled, the symmetry between them was broken, resulting in the distinct forces we observe today.

3. What is the objection to broken electroweak symmetry?

The objection to broken electroweak symmetry is that it is not fully supported by experimental evidence. While the Standard Model of particle physics predicts the existence of the Higgs boson, which is responsible for giving particles their mass and is linked to the concept of broken electroweak symmetry, it has not yet been directly observed.

4. How does Penrose address the objection to broken electroweak symmetry in "The Road to Reality"?

In "The Road to Reality", Penrose discusses the potential implications of the discovery of the Higgs boson on the concept of broken electroweak symmetry. He also explores alternative theories, such as supersymmetry, that could potentially explain the origin of mass and the separation of the weak and electromagnetic forces.

5. Is "The Road to Reality" a suitable book for non-scientists?

"The Road to Reality" is a highly technical and mathematical book that is best suited for those with a strong background in physics and mathematics. It may be challenging for non-scientists to fully understand and appreciate the concepts presented in the book.

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