Dear Professor Dufourny and Mr. Cox,
Thank you for sharing your opinions.
As you mentioned: we cannot still affirm what are the truths, it's very true, because different "assumptions" lead to different models and universes. Nature doesn't know which to follow. However, my philosophy is that truth will surface when certain assumptions are replaced by concrete definitions, which leads to non-designed theories.
It was contended earlier that linear space with micro dimensions cannot be flat with automatic symmetry presence unless sub-geometries exist and once sub-geometries exist, micro dimensions are no longer needed. In fact, no micro dimensions are observed anyway. Therefore, whether it's spheres or strings, it may be more sensible to apply them at the sub-geometries level. The basic math of the sub-geometries, which is not visible at the linear dimensions level as they are on different platforms, is copied from my paper below:
Appendix A - Grand Plan for Future Development - Outline of Classical 3-d, 4-d and 5-d Angle Rotation Field Theories
Classical 2-d angle rotation fields, i.e. EM theory (for 4-d spacetime)
Lorentz gauge condition,
∂Aµ / ∂xµ = 0 (A1)
There are 6 electromagnetic fields rotating between each pair of the 4 linear axes,
FВµП... = ∂AВµ / ∂xП... - ∂AП... / ∂xВµ (Вµ, П... = 0,1,2,3) (A2)
Classical 3-d angle rotation fields (for 5-d spacetime) (conjectured to be weak fields)
For the 3-d angle fields rotating between planes, there are 10 2-d planes in the 5-d spacetime. Let them be named: px1x2, px2x3, px3x1, px0x1, px0x2, px0x3, pxmx1, pxmx2, pxmx3 and px0xm. Imagine a 10-d superspace with each axis being one of these "plane" angle scales running from 00 , 10 , 20 , 30 , .... 3600 , 3610 , 3620 to infinity. The origin of each axis, 0, could be any chosen 2-d surface on the 3-d spacetime. (It can be transformed if a different 2-d surface is chosen as the origin, 0. As to which side of the 2-d surface is pointing to positive of the axis, it is not rigidly defined here, but must be defined rigidly when detailed math is attempted.) To imitate EM, the corresponding 3-d angle Lorentz gauge condition is:
∂Dx1x2 / ∂px1x2 + ∂Dx2x3 / ∂px2x3 + ∂Dx3x1 / ∂px3x1 + ∂Dx0x1 / ∂px0x1
+ ∂Dx0x2 / ∂px0x2 + ∂Dx0x3 / ∂px0x3 + ∂Dxmx1 / ∂pxmx1 + ∂Dxmx2 / ∂pxmx2
+ ∂Dxmx3 / ∂pxmx3 + ∂Dx0xm / ∂px0xm = 0 (A3)
There are 45 3-d angle rotation fields running among the 10 planes:
GxВµxП..., xО»xПЃ = ∂DxВµxП... / ∂pxО»xПЃ - ∂DxО»xПЃ / ∂pxВµxП... (A4)
(where xВµxП... and xО»xПЃ run among the 10 planes and xВµxП..., в‰ xО»xПЃ)
Quantum fields will be obtained upon quantization of the classical fields.
Classical 4-d angle rotation fields (for 5-d spacetime) (conjectured to be CP-violation fields) (omitted)
Classical 5-d angle rotation fields (for 5-d spacetime) (conjectured to be strong fields)
For the 5-d angle theory, there are 5 4-d surfaces in the 5-d spacetime. Let them be named: qx2x3x0xm , qx1x3x0xm , qx1x2x0xm , qx1x2x3xm and qx1x2x3x0. There are 10 5-d angle rotation fields running between the 5 4-d surfaces:
HxВµxП...xПЃxП†, xО»xОѕxПѓxП‡ = ∂ExВµxП...xПЃxП† / ∂c xО»xОѕxПѓxП‡ - ∂E xО»xОѕxПѓxП‡ / ∂cxВµxП...xПЃxП† (A7)
(where xВµxП...xПЃxП† and xО»xОѕxПѓxП‡ run among the 5 4-d surfaces and xВµxП...xПЃxП† в‰ xО»xОѕxПѓxП‡ )
As observed from any 4-d Lorentz frame, the spatial axes, x1, x2, x3, are distinct from xm and time axes, x0, thus the 10 5-d angle rotation fields are grouped into 4 distinct categories: Rotations between 4-d surface pairs qx1x3x0xm-qx2x3x0xm, qx1x2x0xm-qx2x3x0xm and qx1x2x0xm-qx1x3x0xm are equivalent to each other under spatial rotations and are conjectured to cause baryon number. Rotation between 4-d surface pair qx1x2x3x0-qx1x2x3xm is conjectured to cause electron number. Rotations between 4-d surface pairs qx1x2x3x0-qx2x3x0xm, qx1x2x3x0-qx1x3x0xm and qx1x2x3x0-qx1x2x0xm are equivalent and are conjectured to cause muon number. Rotations between 4-d surface pairs qx1x2x3xm-qx2x3x0xm, qx1x2x3xm-qx1x3x0xm and qx1x2x3xm-qx1x2x0xm are equivalent and are conjectured to cause tauonic lepton number. (The reason for these designation is on the assumption that the more xm and x0 are involved, the more massive the particle is, but need to be verified.)
There are 3 5-d angle rotation fields corresponding to the 3 baryon rotations, qx1x3x0xm-qx2x3x0xm, qx1x2x0xm-qx2x3x0xm and qx1x2x0xm-qx1x3x0xm.
Hx1x3x0xm,x2x3x0xm = ∂Kx1x3x0xm / ∂qx2x3x0xm - ∂Kx2x3x0xm / ∂qx1x3x0xm (A8a)
Hx1x2x0xm,x2x3x0xm = ∂Kx1x2x0xm / ∂qx2x3x0xm - ∂Kx2x3x0xm / ∂qx1x2x0xm (A8b)
Hx1x2x0xm,x1x3x0xm = ∂Kx1x2x0xm / ∂qx1x3x0xm - ∂Kx1x3x0xm / ∂qx1x2x0xm (A8c)
Quantum fields will be obtained upon quantization of the classical fields.
There is a lot of math to be done in the sub-geometries. It would be a good idea to discuss with Witten and Susskind. Do you have contact with them?
I also agree with John. The universe may very well be curved, bending toward the xm dimension. But it is completely ignored because only 4 dimensions are recognized today, just like no one would imagine the 2d earth is curved toward the third dimension unless proved by accurate measurement of longer distances.
If accurate measurement of long distances proves the universe is in fact round, then accurate charting may clarify whether the accelerated expansion is actually an illusion.
Happy New Year and Best regards,
Kwan Chiang
1/4/2022