Here are some explanatory notes that can help us better understand the problem of twin paradox.

**Alternative method for finding the age of Zarak:**

Zarak’s age can be found by using one another approach. When the spacecraft goes with a velocity of 0.8c, the distance from earth to the star contracts. If we find the contracted distance and then apply the simple formula of S = vt, we can find the time Zarak takes on his round trip visit. That time will be the age of Zarak.

From earth point of view

Distance to the destination star = l_{0} = 30 light years

Both sides journey = 2 × 30 = 60 light years.

In terms of kilometers = 60 × 94608 × 10^{11} m. = ℓ

velocity = 0.8 c = 0.8 × 10^{8} m/s.

Formula:

Put the value of ℓ, v and c.

Now apply formula t = s/v

**What is light year?**

Light year is the unit of distance when we deal with relativistic mechanics. “It is the distance light covers in one year”. Mathematically,

1 light year = 3 × 10^{8} × 60 × 60 × 24 × 365 = 94608000 × 10^{8 }m.

**What is a paradox?**

د پیراډاکس مطلب داسی یوکار یا خبره چی پهٔ ظاهره خو صحیح لګي ولی د عقل او منطق پهٔ بنیاد د منلو نهٔ وي.

**Twin Paradox**

Twin paradox is the problem of exact ages of twin siblings in the case when one of them goes to space and the other remains on earth. Time “delays” and lengths “contract” when we deal with relativistic velocities. Therefore, there must be difference in the ages of twin brothers/sisters when one of them goes to space in a spaceship and the other remains on the earth. There are different approaches to the problem and different opinions. (Note that no such thing has happened yet and this is just an imaginary situation called thought experiment).

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