The equivalence principle (EP) is a basic assumption of the general relativity. The quantum test ... more The equivalence principle (EP) is a basic assumption of the general relativity. The quantum test of the equivalence principle with atoms is an important way to examine the applicable scope of the current physical framework so as to discover new physics. Recently, we extended the traditional pure mass or energy tests of the equivalence principle to the joint test of mass–energy by atom interferometry (Zhou et al.,Phys.Rev.A 104,022822). The violation parameter of mass is constrained to η0 = (−0.8 ± 1.4) × 10–10 and that of internal energy to ηE = (0.0 ± 0.4) × 10–10 per reduced energy ratio. Here, we first briefly outline the joint test idea and experimental results, and then, we analyze and discuss how to improve the test accuracy. Finally, we report the latest experimental progress toward a high-precision mass–energy test of the equivalence principle. We realize atom interference fringes of 2T = 2.6 s in the 10-m long-baseline atom interferometer. This free evolution time T, to the...
To the second order in metric and the first order in equations of motion in the local coordinates... more To the second order in metric and the first order in equations of motion in the local coordinates of an accelerated rotating observer, the inertial effects and gravitational effects are simply additive. To look into the coupled inertial and gravitational effects, we derive the third-order expansion of the metric and the second-order expansion of the equations of motion in local coordinates. Besides purely gravitational (purely curvature) effects, the equations of motion contain, in this order, the following coupled inertial and gravitational effects: redshift corrections to electric, magnetic, and double-magnetic type curvature forces; velocity-induced special relativistic corrections; and electric, magnetic, and double-magnetic type coupled inertial and gravitational forces. An example is provided with a static observer in the Schwarzchild spacetime.
International Journal of Modern Physics D, Sep 1, 2011
For detecting gravitational waves in space, deep-space laser ranging using drag-free spacecraft i... more For detecting gravitational waves in space, deep-space laser ranging using drag-free spacecraft is a common method. Deep space provides a large arena and a long integration time. Laser technology provides measurement sensitivity, while drag-free technology ensures gravitational phenomenon to be measured with least spurious noises. In this talk, we give an overview of motivations and methods of various space missions/proposals for detecting gravitational waves, and refer them to various references.
ABSTRACT Ephemeris is necessary for mission orbit design. For non-astrodynamical missions, an exi... more ABSTRACT Ephemeris is necessary for mission orbit design. For non-astrodynamical missions, an existing ephemeris like JPL DE 405 and 406 can be used for this purpose. For astrodynamical missions, one needs to have a working ephemeris flexible enough that one can do orbit simulation for mission design, and orbit determination and astrodynamical-parameter fitting during actual mission. In real-time with the astrodynamical mission, the working ephemeris is continuously improved. After the mission the working ephemeris would be better than all previously existing ephemeris at least for certain parts of the ephemeris. For the ASTROD orbit design and simulation, we have worked out CGC 1 and CGC 2 ephemeris framework. Here we describe how CGC 2 ephemeris framework is built (CGC: Center for Gravitation and Cosmology). In the CGC 2 framework, we include the Sun, nine planets, the Moon and 3 big asteroids in a mutually interacting evolution with the solar field to the post-Newtonian order. Solar quadrupole moment and Earth's quadrupole moment are also included. We include additional 489 asteroids with diameter larger than 65 km in the calculation of the perturbation of orbits of nine planets, the Sun, the Moon and the 3 big asteroids. To simplify calculation, the heliocentric orbits of these 489 asteroids are determined by the Kepler elements. The computing program (in C++) is open to public. A comparison of CGC 2 with DE 405 for the range, latitude and longitude of Mercury and Mars in the Earth-Moon mass-center equatorial coordinate frame for 1200 days after the initial time shows that the deviations from DE 405 are below 0.5 km in range, 0.3 mas in latitude and 1.2 mas in longitude.
The equivalence principle (EP) is a basic assumption of the general relativity. The quantum test ... more The equivalence principle (EP) is a basic assumption of the general relativity. The quantum test of the equivalence principle with atoms is an important way to examine the applicable scope of the current physical framework so as to discover new physics. Recently, we extended the traditional pure mass or energy tests of the equivalence principle to the joint test of mass–energy by atom interferometry (Zhou et al.,Phys.Rev.A 104,022822). The violation parameter of mass is constrained to η0 = (−0.8 ± 1.4) × 10–10 and that of internal energy to ηE = (0.0 ± 0.4) × 10–10 per reduced energy ratio. Here, we first briefly outline the joint test idea and experimental results, and then, we analyze and discuss how to improve the test accuracy. Finally, we report the latest experimental progress toward a high-precision mass–energy test of the equivalence principle. We realize atom interference fringes of 2T = 2.6 s in the 10-m long-baseline atom interferometer. This free evolution time T, to the...
To the second order in metric and the first order in equations of motion in the local coordinates... more To the second order in metric and the first order in equations of motion in the local coordinates of an accelerated rotating observer, the inertial effects and gravitational effects are simply additive. To look into the coupled inertial and gravitational effects, we derive the third-order expansion of the metric and the second-order expansion of the equations of motion in local coordinates. Besides purely gravitational (purely curvature) effects, the equations of motion contain, in this order, the following coupled inertial and gravitational effects: redshift corrections to electric, magnetic, and double-magnetic type curvature forces; velocity-induced special relativistic corrections; and electric, magnetic, and double-magnetic type coupled inertial and gravitational forces. An example is provided with a static observer in the Schwarzchild spacetime.
International Journal of Modern Physics D, Sep 1, 2011
For detecting gravitational waves in space, deep-space laser ranging using drag-free spacecraft i... more For detecting gravitational waves in space, deep-space laser ranging using drag-free spacecraft is a common method. Deep space provides a large arena and a long integration time. Laser technology provides measurement sensitivity, while drag-free technology ensures gravitational phenomenon to be measured with least spurious noises. In this talk, we give an overview of motivations and methods of various space missions/proposals for detecting gravitational waves, and refer them to various references.
ABSTRACT Ephemeris is necessary for mission orbit design. For non-astrodynamical missions, an exi... more ABSTRACT Ephemeris is necessary for mission orbit design. For non-astrodynamical missions, an existing ephemeris like JPL DE 405 and 406 can be used for this purpose. For astrodynamical missions, one needs to have a working ephemeris flexible enough that one can do orbit simulation for mission design, and orbit determination and astrodynamical-parameter fitting during actual mission. In real-time with the astrodynamical mission, the working ephemeris is continuously improved. After the mission the working ephemeris would be better than all previously existing ephemeris at least for certain parts of the ephemeris. For the ASTROD orbit design and simulation, we have worked out CGC 1 and CGC 2 ephemeris framework. Here we describe how CGC 2 ephemeris framework is built (CGC: Center for Gravitation and Cosmology). In the CGC 2 framework, we include the Sun, nine planets, the Moon and 3 big asteroids in a mutually interacting evolution with the solar field to the post-Newtonian order. Solar quadrupole moment and Earth's quadrupole moment are also included. We include additional 489 asteroids with diameter larger than 65 km in the calculation of the perturbation of orbits of nine planets, the Sun, the Moon and the 3 big asteroids. To simplify calculation, the heliocentric orbits of these 489 asteroids are determined by the Kepler elements. The computing program (in C++) is open to public. A comparison of CGC 2 with DE 405 for the range, latitude and longitude of Mercury and Mars in the Earth-Moon mass-center equatorial coordinate frame for 1200 days after the initial time shows that the deviations from DE 405 are below 0.5 km in range, 0.3 mas in latitude and 1.2 mas in longitude.
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Papers by Wei-Tou Ni