November 3, 2000
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October 24, 1996
If Lorentz invariance is only an approximate property of equations describing a sector of matter above some critical distance scale, the speed of light c will not necessarily be the only critical speed in vacuum. Superluminal sectors of matter may exist related to new degrees of freedom not yet discovered experimentally. The new particles would not be tachyons: they may feel different minkowskian space-times with critical speeds much higher than c and behave kinematically lik...
December 4, 2010
We report the first direct photon velocity measurements for extragalactic objects. A fiber-optic, photon time-of-flight instrument, optimized for relatively dim sources ($m 12$), is used to measure the velocity of visible photons emanating from galaxies and quasars. Lightspeed is found to be $3.00\pm0.03\times10^{8} \mathrm{m s}^{-1}$, and is invariant, within experimental error, over the range of redshifts measured ($0\leq z\leq1.33$). This measurement provides additional va...
July 14, 2004
It has always been considered a serious error to treat the cosmological redshift as a Doppler velocity effect rather than the result of space expansion. It is demonstrated here that in practical terms this is not the case, and that the apparent distance - redshift relation derived from a Doppler interpretation is reasonably consistent with supernova data (though not as good as the standard model with dark energy). The normal Doppler effect is examined in detail and shown to c...
September 8, 2009
It is well known that interstellar travel is bounded by the finite speed of light, but on very large scales any rocketeer would also need to consider the influence of cosmological expansion on their journey. This paper examines accelerated journeys within the framework of Friedmann- Lemaitre-Robertson-Walker universes, illustrating how the duration of a fixed acceleration sharply divides exploration over interstellar and intergalactic distances. Furthermore, we show how the u...
March 24, 2023
The Robertson-Walker (RW) metric allows us to apply general relativity to model the behavior of the Universe as a whole (i.e., cosmology). We can properly interpret various cosmological observations, like the cosmological redshift, the Hubble parameter, geometrical distances, and so on, if we identify fundamental observers with individual galaxies. That is to say that the interpretation of observations of modern cosmology relies on the RW metric. The RW model satisfies the co...
October 1, 2008
The space expansion physics contains several paradoxes which were clearly demonstrated by Edward Harrison (1981, 1995, 2000), who emphasized that the cooling of homogeneous hot gas (including photon gas of CBR) in the standard cosmological model based on the violation of energy conservation by the expanding space. In modern version of SCM the term "space expansion" actually means continuous creation of vacuum, something that leads to conceptual problems. Recent discussion by ...
February 9, 2014
We present a derivation of the cosmological distance-redshift relation up to second order in perturbation theory. In addition, we find the observed redshift and the lensing magnification to second order. We do not require that the density contrast is small, we only that the metric potentials and peculiar velocities are small. Thus our results apply into the nonlinear regime, and can be used for most dark energy models. We present the results in a form which can be readily com...
February 14, 2008
After a brief introduction to the sixteenth and seventeenth century views of the Universe and the nineteenth century paradox of Olbers, we start the history of the cosmic expansion with Hubble's epochal discovery of the recession velocities of spiral galaxies. By then Einstein's theories of relativity were well known, but no suitable metric was known. Prior to introducing General Relativity we embark on a non-chronological derivation of the Robertson-Walker metric directly fr...
March 22, 2021
Most cosmological data analysis today relies on the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric, providing the basis of the current standard cosmological model. Within this framework, interesting tensions between our increasingly precise data and theoretical predictions are coming to light. It is therefore reasonable to explore the potential for cosmological analysis outside of the exact FLRW cosmological framework. In this work we adopt the general luminosity-distance ...
October 12, 1996
The apparent Lorentz invariance of the laws of physics does not imply that space-time is indeed minkowskian. We consider a scenario where Lorentz invariance is only an approximate property of equations of matter above a certain distance scale, and superluminal sectors of matter exist related to new degrees of freedom not yet discovered experimentally. The new particles would not be tachyons: they may feel different minkowskian space-times with critical speeds much higher than...