10 мая 2018 г. · The four velocity is the tangent vector to a world line, and null or indeed spacelike world lines still have tangent vectors. But we'd have to ...

16 мая 2019 г. · In our four-geometry we define the four-velocity →U to be a vector tangent to the world line of the particle, and of such a length that it ...

30 окт. 2020 г. · A potential source of confusion is that the photon frequency is a Lorentz scalar, but also observer-dependent. In order to clarify, ...

14 нояб. 2023 г. · Physical Interpretation: The four-velocity's magnitude is always the speed of light, which reflects the constancy of the speed of light in ...

26 мая 2015 г. · The 4-momentum is defined as p=mU where m is the rest mass of the particle and U is the 4-velocity. Now I am confused as to how this applies to ...

12 апр. 2017 г. · Yes, but in SR as well. Energy depends on both the object being observed and the observer. Just think of a photon. Sure it has an energy E=hf if ...

5 авг. 2019 г. · The velocity is v=−drdt (minus sign because the gas is moving inward); The four-velocity components are usually written as Uμ=d ...

14 мая 2021 г. · Considering four-velocity (derivative of "proper length" with respect to "proper time"), the invariant becomes the square of speed of light, and ...

2 мар. 2023 г. · Yes, but it is more general than this. The norm of any 4-vector is invariant under arbitrary coordinate transformations in any spacetime.

23 нояб. 2016 г. · If a photon has four-momentum Pa then its three-momentum, relative to the frame defined by a unit time-like vector Va is ERa=Pa−VaPbVb, where E ...