<p>Referring to the twin paradox, where we have an Earth Bound Twin “EBT”  and a Traveling Twin “TT” who travels away from Earth at velocity= .8c, lets say to Alpha Centauri, when the TT is half way there, what would the TT calculate as how much his EBT’s aged at that point?</p>
<p>To simplify, round the distance to Alphas Centauri to say 4 lightyears.</p>
<hr />
<p>I am thinking .8c yields a lambda of .6 and so the TT’s  4 lightyear trip, reduced to 2.4 lightyears due to space contraction. Therefore the midway point is only 1.2 light years. Traveling at .8c, means the TT must himself be 1.2/.8…. 1.5 years older at the midway point.</p>
<p>Since his EBT, relatively, is “traveling” at v=-.8c during this time, his EBT must appear to age relatively slower compared to him.  Using the lambda of .6, the TT would calculate as the amount aged by his EBT to be 1.5*.6=.9 years.</p>
<p>Is this correct?</p>

CC BY-SA 4.0
2020-09-12T18:48:45.887Z
Is this really a hard question? Either I don't understand relativity in this context and someone can point that out to me or its just a little math and someone should be able to do it?
ParityViolator
CC BY-SA 4.0
2020-10-04T11:58:30.320Z
This doesn't relate to astronomy, and is more a pure physics thought experiment
James K
<special-relativity><time-dilation>
Thinking about the Twin Paradox, what would a Twin Traveling at .8c, calculate as the amount his EBT aged at the mid-point in a 4 lightyear trip?
ParityViolator
# Thinking about the Twin Paradox, what would a Twin Traveling at .8c, calculate as the amount his EBT aged at the mid-point in a 4 lightyear trip?

(Asked by: username_0 on 2020-09-09)

Referring to the twin paradox, where we have an Earth Bound Twin “EBT” and a Traveling Twin “TT” who travels away from Earth at velocity= .8c, lets say to Alpha Centauri, when the TT is half way there, what would the TT calculate as how much his EBT’s aged at that point?

To simplify, round the distance to Alphas Centauri to say 4 lightyears.

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I am thinking .8c yields a lambda of .6 and so the TT’s 4 lightyear trip, reduced to 2.4 lightyears due to space contraction. Therefore the midway point is only 1.2 light years. Traveling at .8c, means the TT must himself be 1.2/.8…. 1.5 years older at the midway point.

Since his EBT, relatively, is “traveling” at v=-.8c during this time, his EBT must appear to age relatively slower compared to him. Using the lambda of .6, the TT would calculate as the amount aged by his EBT to be 1.5\*.6=.9 years.

Is this correct?

**Tags:** special-relativity, time-dilation

> **Comments:**
> **username_0**: Is this really a hard question? Either I don't understand relativity in this context and someone can point that out to me or its just a little math and someone should be able to do it?  
> **username_1**: This doesn't relate to astronomy, and is more a pure physics thought experiment  

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## 0 answers

