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Different places on the web imply that Schwarzschild's metric uses four components or separate equations, similar to how Einstein's full set requires 6 or 10, or they say only two are needed. Is it 2 …

The Friedmann equations can be solved exactly in presence of a perfect fluid with equation of state $${\displaystyle p=w\rho c^{2}} \qquad p=w\rho c^2$$ where ${\displaystyle p}$ is the pressure, ${\d …

And: These are from Wikipedia on Schwarzschild metric, Derivation of the Schwarzschild metric and the last is from Science Direct, Schwarzschild metric.

From what I understand, stars that explode as a supernova at the end of their lives become either a black hole or a neutron star, and less massive stars that do not explode become white dwarves, but.. …

Over the past year and a half, multiple articles in the popular press have come out talking about how unexpectedly rapidly Titan is moving away from Saturn, and how this is causing Saturn to wobble mo …

From the year-end issue of New Scientist Magazine (Dec. 18-31,2021): Astronomy: 'Space Cow' explosion was probably a failed supernova' Page 10: 'They found that the strength of this radiation oscill …

One site I came across says Einstein's 10 Field Equations use 20 variables, while another said 40. There are four variables in spacetime - three for space and one for time, right? But there are two in …

As @PeterErwin's comment compassionately points out: "Acceleration" means changing the velocity vector, so an object in a circular orbit is always "accelerating" (because the direction of the velocit …

Is it related to the way they deduce the Hubble constant from Planck data? Would more types of oscillating and mixing neutrinos mean faster or slower expansion of the universe? Would a fourth mass eig …

I have heard a lot recently about so-called 'dark stars'; stars that are formed with the help of the gravitational pull of dark matter, or perhaps entirely from self-annihilating Majorana-type dark pa …

Many popular and professional science sites said something about Stephen Hawking's black hole area theorem being proven observationally, finally, not just mathematically, to 95% confidence. For exampl …

Obviously, the speed of light is a presumed limit, at least for 'physical' objects moving 'within' ('through'?) spacetime, but... In recent news some scientists believe they have figured out the appro …

In the Modified Theory of Newtonian Gravity or MOND, they say that massive objects, accelerating slowly, experience this modified gravity. But are they actually gaining in velocity, albeit very slowly …

Somehow, I have never come across an explanation of why cosmologists claim that the alleged inflation of the very early universe occurred not at the Big Bang, but very shortly afterwards (~10^-36 to 1 …

So-called 'hairless' black holes (no-hair theory, or theorem?) , which is what real black holes are, can be described by just three characteristics: Mass, spin, and charge. It is easy enough to contem …