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1

There is quite a nice explanation on this web page. A key passage is this: in curved spacetime there aren't these "best" co-ordinate systems, the inertial ones. So even very reasonable different choices of co-ordinates can give disagreements about particles vs antiparticles, or what's the vacuum. These disagreements don't mean that "everything is ...


0

Perhaps this was a galactic black hole and is now a remnant from a previously accreted galaxy. Our Milky Way is rather large and could have swallowed up a smaller galaxy.


1

If you are talking about the temperature of the event horizon, then it depends on the mass. Super-massive black holes have a temperature of $1.4 \times 10^{-14}$ Kelvin while a solar mass black hole has a temperature of only $6.0 \times 10^{-8}$ Kelvin. This temperature comes from the proposed Hawking radiation of black holes$^1$. The reference below gives ...


3

See Hawking radiation. The temperature of a black hole depends on its mass, and is given by: $T=\frac{hc^3}{16\pi^2GMk_B}$ Where $h$ is the Planck constant, $c$ is the speed of light, $G$ is Newton's gravitational constant, $M$ is the mass of the black hole, and $k_B$ is the Boltzmann constant.


30

There're several pieces of information one needs to understand this. Although stars more massive than 70 solar masses exist, when they become black holes, they usually lose mass in the process. The exact amount of mass lost depends on the metallicity (which is a technical term that describes how much "metals" - the astronomer's definition of metals is ...


1

In special relativity, changes of reference frame are symmetric between observer and observee. If moving a neutron star gave it enough kinetic energy to become a black hole, then you could effect this change by jumping into a moving reference frame yourself. What matters is the neutron star's mass in its rest frame.


5

The shape of the surface shown in the video is a depiction of the spacial curvature of the spacetime. (The relationship with time are depicted seperately by the arrows and the colors.) More particularly, the shape is depicting the curvature of equatorial plane of the binary. The depicted surface has been embedded in a (fictional) 3D space in such away that ...


2

tldr; extremely little. Space is big, even biggest black holes are ridiculously tiny in physical size The amount of starlight absorbed by black holes is really minuscule. A black hole is not going to be sucking light in: it can be fairly well approximated to be an absolutely black object around the size of its event horizon (or photon sphere, does not ...


3

According to Ginsburg, Loeb & Wegner (2012) "Hypervelocity planets and transits around hypervelocity stars", planet-hosting hypervelocity stars could form from the disruption of a stellar binary by a massive black hole, and the probability that the planet remains bound to the hypervelocity star is fairly high for suitable initial conditions. In their ...


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