Status Updates From المجرَّات: مقدمة قصيرة جداً

🙄اوكي غلطتي التسجيل الأخير

شيييق للآن لكن كنت تحت المُراقبة مما جعل الكلمات تتطاير يساري وحولي، حاولت أصطياد قدر قادر

"Relativistic effects become important once we are dealing with
‘velocities’ bigger than about a third of the speed of light. Once we take these effects into account, a redshift of 2, for example, does not mean that an object is receding from us at twice the speed of light but at 80 per cent of the speed of light; a redshift of 4 corresponds to a recession velocity of 92 per cent of the speed of light"

"The cosmological redshift is not a Doppler effect caused by galaxies moving outward through space [...] the spaces between galaxies increase while light is on its way from one galaxy to another. This stretches the light waves to longer wavelengths, which means shifting them towards the red end of the spectrum."

"In fact, any object will become a black hole if it is sufficiently compressed.
For any mass, there is a critical radius, called the Schwarzschild radius, for
which this occurs. For the Sun, the Schwarzschild radius is just under 3 km;
for the Earth, it is just under 1 cm. In either case, if the entire mass of the
object were squeezed within the appropriate Schwarzschild radius it would
become a black hole"

" [the spiral shape of a galaxy] persists because it is a wave of star formation maintained by clouds of gas and dust moving around the Galaxy in their own orbits and being squeezed as they cross the spiral arms"

" (...) cosmological redshift is not caused my motion through space and is not a Doppler effect. "

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