Saturday, May 04, 2019

Universe and its expansion

Oldest Star in the Milky Way      

Astronomers have found one of the oldest stars in the Milky Way and possibly one of the oldest in the universe, a body made up almost entirely of elements generated in the Big Bang birth of the cosmos.

The tiny, 13.5-billion-year-old star is part of the Milky Way’s “thin disk,” the realm where the sun resides. Given the age of the newly discovered star, the solar system’s neighbourhood may be up to three billion years older than previously thought.

This is the problem I have. Read a bit of this which says it is only about 1,950 ly (600 pc) fron Earth. How come this star is in the Milky Way. Why is it still around, if we think there was a Big Bang around 14 billion years ago?  It should have gone beyond it's 'eat by date' has gone?  And why don't it have a red-shift, indicating it is flying away from us?

Gravity

What is gravity has f****** lots of human's brain out. So simple explanation huh? Wikipedia says this:

Gravity (from Latin gravitas, meaning 'weight'[1]), or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light[2]—are brought toward (or gravitate toward) one another. On Earth, gravity gives weight to physical objects, and the Moon's gravity causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing, forming stars – and for the stars to group together into galaxies – so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become increasingly weaker on farther objects.

Not so smple is it?
And then I came across the Einstein's General Relativity theory. In that :

The prediction of the deflection of light was first confirmed by Arthur Stanley Eddington from his observations during the Solar eclipse of 29 May 1919.[23][24] Eddington measured starlight deflections twice those predicted by Newtonian corpuscular theory, in accordance with the predictions of general relativity. However, his interpretation of the results was later disputed.[25] More recent tests using radio interferometric measurements of quasars passing behind the Sun have more accurately and consistently confirmed the deflection of light to the degree predicted by general relativity.[26] See also gravitational lens.

So if we know the dimention of the Sun, the distance to the quasar, and the speed of light, can't we get a solution for gravity in terms of seconds and meters? And we know that the gravity of the Sun is 28 times that of Earth. I am not a maths boffin so I am afraid I cannot do any investigation into this.  In the bucket list li (loving it)