Do White Holes Exist?

Do Black Holes Exist?

Proof that black holes exist will likely require confirmation of the existence of event horizons. The common assumption that the mere existence of large compact masses proves the case for black holes is an unwarranted extrapolation of General Relativity into a strong-field regime where it has not been adequately tested. Neither the large compact masses of galactic nuclei nor the massive compact...

Do Black Holes Exist?

Do semiclassical zero temperature black holes exist?

The semiclassical Einstein equations are solved to first order in epsilon = Planck's over 2pi/M2 for the case of a Reissner-Nordström black hole perturbed by the vacuum stress energy of quantized free fields. Massless and massive fields of spin 0, 1/2, and 1 are considered. We show that in all physically realistic cases, macroscopic zero temperature black hole solutions do not exist. Any static...

Do Supermassive Black Holes Exist at the Center of Galaxies?

General relativistic models of star clusters with large redshifts are investigated to see whether such objects can be stable and long-lived based on evaporation and collision timescales and stability criteria. We find that physically reasonable models of massive clusters of stellar remnants can exist with masses ≥ 10 M⊙, which could simulate black holes at the center of galaxies with large M/L ...

Primordial Black Holes: Do They Exist and Are They Useful?

Recent developments in the study of primordial black holes (PBHs) are reviewed, with particular emphasis on their formation and evaporation. It is still not clear whether PBHs formed but, if they did, they could provide a unique probe of the early Universe, gravitational collapse, high energy physics and quantum gravity. Indeed their study may place interesting constraints on the physics releva...