hello-every-one-how-do-they-calculated-the-universe-old-wich-is-13-8-billion-years-

Question Number 97885 by M±th+et+s last updated on 10/Jun/20

h e l l o e v e r y o n e

h o w d o t h e y c a l c u l a t e d t h e u n i v e r s e o l d

w i c h i s 13.8 b i l l i o n y e a r s

Commented by EmericGent last updated on 10/Jun/20

One way is use the density in function of time and see when the density reach Planck's limit

Commented by M±th+et+s last updated on 10/Jun/20

t h a n x f o r a l l

Answered by smridha last updated on 10/Jun/20

y o u c a n p r o v e t h i s b y i n t r o d u c i n g

H u b b l e c o n s t a n t (H_{0}) \dots

b u t t h e f a c t i s o u r u n i v e r s e i s

e x p a n d i n g, n o t i n c o n s t a n t r a t e

i t i s a c c e l a r a t i n g s o a g e

o f u n i v e r s e c a n n o t d e t e r m i n e

p e r f e c t l y, t h i s i s j u s t a t h e o r i t i c a l

v a l u e \dots

w e l l I c a n p r o v e t h i s \dots

Commented by M±th+et+s last updated on 10/Jun/20

s i r y o u m e a n t h i s r u l e

t_{0} = \frac{2}{3} \times \frac{1}{H_{0} \sqrt{Ω_{v_{0}}}} {s i n h}^{- 1} (\sqrt{\frac{3 Ω_{v_{0}}}{2 (1 + q_{0}}})

a n d i h o p e i f y o u h a v e a t i m e s h o w t h e

p r o v e a n d t h a n k y o u .

Commented by smridha last updated on 10/Jun/20

i t s w e l l b u t y o u c a n a l s o d e t e r m i n e

i t i n e a s i e s t w a y l i k e . .

\frac{1}{H_{0}} = a g e o f t h e u n i v e r s e

H_{0} = \frac{73 k m / s}{1 M p c} i t m e a n s i f t h e

d i s t a n t {b e t}^{n} t w o g a l a x y i e s i s

1 M p c t h e n t h e r e l a t i v e v e l o c i t y

o f m o v i n g a w a y f r o m o n e t o o t h e r

i s 73 k m / s .

s o y o u c a n s e e i m e d e a t e l y t h a t

d i s t a n t a n d v e l o c i t y i s p r o p o r t i o n a l

a n d t h e p r o p o r t i o n a l i t y c o n s t a n t

i s H_{0} . . t h i s i s c a l l e d H {u b b l e}^{'} s l a w .

Commented by smridha last updated on 10/Jun/20

t h a n k y o u \dots

Commented by M±th+et+s last updated on 10/Jun/20

g o d b l e s s y o u s i r

Answered by Rio Michael last updated on 10/Jun/20

The truth is that we cannot actually determine

the actual age of the universe due to its expanding

nature . Astronomers tell us that the universe is

about 13.7 to 13.8 billion years . They do calculations

- Based on the oldest star (methusela star) .

- by measuring the rate at which the universe is

expanding from the big bang start point .