Abstract

In four dimensions, the Minkowski metric leads to the 16-dimensional Clifford algebra C(1,3), Dirac's equation [1] is using four of these 16 matrices that form a basis of this algebra, a new operator is defined using all of these matrices and also generalized for a curved space. This new multilevel operator generalizes the Dirac's equation, the value of the generalized Dirac's operator is calculated in the Schwarzschild's metric. The torsion tensor is calculated taking into account the non-symmetric part of the metric tensor in the vanishing of its covariant derivative and applied to Kerr's metric generalizing the Clifford algebra.

Key Words

Gravitomagnetic Tensor; Gravitational Magnetic Field; Energymomentum1-Form; Clifford Algebra; Dirac Equation; Dirac Operator; Gravity and Quantum Mechanics Unification; Multilevel Operator; Schwarzschild's Metric; Torsion Tensor; Rearranged Kerr's Metric; Generalized Clifford Algebra

Introduction

Dirac's equation is the relativistic wave equation derived by physicist Paul Dirac in 1928. The wave functions in the Dirac theory are vectors of four complex components (known as bispinors), two of which resemble the Pauli wavefunction in the non-relativistic limit, in contrast to the Schrodinger equation which described wave functions of only one complex component [1, 2].

Dirac's operator is just the tip of the iceberg, the tip of a generalized operator that is obtained by operating on all members of the Clifford algebra basis and not just on four of them.

The Schwarzschild's metric is named in honour of Karl Schwarzschild, who found the exact solution in 1915 and published it in January 1916, a little more than a month after the publication of Einstein's theory of general relativity. It was the first exact solution of the Einstein field equations other than the trivial at space solution. Schwarzschild died shortly after his paper was published, as a result of a disease he developed while serving in the German army during World War I. Johannes Droste in 1916 independently produced the same solution as Schwarzschild.

Schwarzschild's metric is an exact solution to the Einstein's field equations that describes the gravitational field outside a spherical mass, on the assumption that the electric charge of the mass, angular momentum of the mass, and universal cosmological constant is all zero.

The new generalized Dirac's operator, the multilevel operator, is calculated in the Schwarzschild's metric, torsion tensor and new gravitomagnetic tensor appear in level 2, curvature tensor appears in levels 3 and 4.

The Kerr's metric is a generalization to a rotating body of the Schwarzschild's metric.

Multilevel operator

We are using Pauli matrices σ, electromagnetic four-potential and charge e with

                                                                                                                                              1

In four dimensions, Minkowski's metric η_μν = diag (+1,-1,-1,-1) leads to the Clifford algebra C(1,3)[2],  Dirac matrices

                                                                                                               2

Multilevel operator Dⁿ  acts on level n, n is the number of matrices in the product of the algebra members, for example, D³ acts on γ¹⁰, γ¹¹, γ¹², and γ¹³. Total multilevel operator = D⁰ +D¹ +D² +D³ +D⁴, the action of on the spinor function vanishes ψ=0                                      3

                                                                                                                                                                                                                                            4

                                                                                                                                                                                                                        5

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                                                                                                                                                         8

                                                                                                                                           9

Multilevel operator can be generalized for a curved space with four-potential P, field charge q and covariant derivative [3] instead of derivative  in the definition of

                                                                                                                                                                                                                      10

                                                                                                                                                                                                                           11

                                                                                                                                                                                                                                             12

                                                                                                                                                                                                                         13

 with                                                                                                                                                                                     14

                                                                                                                                                                                  15

                                                                                                                                                                                                                16

                                                                                                                                                                             17

For gravity  is the new gravitomagnetic tensor.  is the torsion tensor [4].

                                                                                                                                                               18

 with  the Riemann-Christoffel tensor [5].                                                                                                                                       19

                                                                                                         20

                                                                                                                                               21

                                                                                                                                                                                         22

                                                                                                                                                               23

Gravitomagnetic Tensor Defined in Schwarzschild's Metric

We are using  with , this metric is defined by [6]

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                                                                                                                                                                                                                       28

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                                                                                                                                                                                                                              30

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                                                                                                                                                                                                                          33

                                                                                                                                                                                                                          34

                                                                                                                                                                                                                      35

                                                                                                                                                                                                                     36

                                                                                                                                                                                                                37

                                                                                                                                                                                                                 38

                                                                                                                                                                                                   39

, from equations (16) and (17)                                                                                                                  40

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                                                                                                                                                         42

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                                                                                                                                                       44

                                                                                                                                                                    45

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                                                                                                                                                                   47

Energy-momentum form is a 1-form [7]                                                                                             

                                                                                                                                                                                           48

dp is a 2-form

                                                                                     49

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                                                                                                                                                                                                                      51

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Comparing equations (41-43) and (50-52) we can infer

                                                                                                                                                                                                                                       53

 is related to the scalar 0 -form  is related to the Energy-momentum 1-form, is related to the Electromagnetic 2 -form, is related to
3-form [8].

                                                                                                                                                                                                                  54

is related to L 4-form [9].                                                                                                                

                                                                                                                                                                                          55

 is the proyector matrix, historically

                                                                                                                         56

Torsion Tensor in a Rearranged Kerr's Metric

We are using  M is the black hole's mass and a is the angular momentum per unit mass with G = c = 1. The invariance of the length of vectors under parallel transport means that the connection is compatible with the metric, it is a metric connection, the requirement of the preservation of the length by parallel transport may be stated as [10].

                                                                                                                                                                                                                                57

                                                                                                                                                                          58

, with                                                                                                              59

                                                                                                                                                             60

                                                                                                                                                                       61

                                                                                                                                                                  62

Solving these equations, we get the torsion applying its definition [11].

                                                                                                                                                                                                                63

Expanding the line element in powers of  and examining the leading terms [12].

                                                      64

Rearranging the line elements

                                  65

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                                                                                                                                                                                                                                   75

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                                                                                                                                                                                            78

Generalizing Clifford algebra with , if  and  then 1, else 0

                                                                                                                                                                       79

                                                                                                                                        80

                                                                                                                                                                                       81

                                                                                                                                                                                82

                                                                                                                                    83

, from equations (16) and (17)                                                                                                              84

                                                                                                                 85

                                                                       86

                                                              87

                  88

                                                             89

                                                                                                                                                                                   90

 is the proyector matrix, historically , but

                                                                                                                                                                   91

Conclusions

Multilevel operator  has been generalized for a curved space with a general four-potential P. For gravity  is the new gravitomagnetic tensor and torsion tensor  appears in its definition.

In a at space  and operators vanish. In a curved space the curvature tensor  appears in levels 3 and 4.

The appearance of torsion tensor  and curvature tensor  in multilevel operator  means that this operator is a fundamental operator in Quantum Field Theory.

, have been calculated for Schwarzschild's metric, then , the gravitomagnetic tensor has been obtained

Each, where n is the number of γ matrices in the product of the algebra members, is related to an n-form.

The invariance of the length of vectors under parallel transport requires the vanishing of the metric tensor covariant derivative, a new term appears in equation (59) with  measuring the non-symmetric part of the metric tensor, solving these equations we get the torsion tensor.

Rearranging Kerr's metric we obtained , the non-symmetric part of the metric tensor, gravitomagnetic tensor has also been calculated generalizing the Clifford algebra.

References

1. Marian Fecko (2006) Differential Geometry and Lie Groups for Physicists. Cambridge University Press 637.
2. Marian Fecko (2006) Differential Geometry and Lie Groups for Physicists. Cambridge University Press 650-652.
3. Marian Fecko (2006) Differential Geometry and Lie Groups for Physicists. Cambridge University Press 380.
4. Marian Fecko (2006) Differential Geometry and Lie Groups for Physicists. Cambridge University Press 384.
5. Marian Fecko (2006) Differential Geometry and Lie Groups for Physicists. Cambridge University Press 404.
6. P.A.M. Dirac (1996) General Theory of Relativity. Princeton University Press 30-32.
7. J.A. Wheeler., C. Misner., K.S. Thorne (2017) Gravitation. Princeton University Press 91.
8. Roger Penrose (2006) El camino a la realidad. Random House Mondadori, Barcelona 603.
9. J.A. Wheeler., C. Misner., K.S. Thorne (2017) Gravitation. Princeton University Press 119.
10. Marian Fecko (2006) Differential Geometry and Lie Groups for Physicists. Cambridge University Press 383.
11. Marian Fecko (2006) Differential Geometry and Lie Groups for Physicists. Cambridge University Press 389.
12. J.A. Wheeler., C. Misner., K.S. Thorne (2017) Gravitation. Princeton University Press 891.