# Twin Paradox: Can Barbara Reach XEON Alive?

• ucsaint
In summary, Barbara will reach the planet XEON alive if her spaceship is fast enough. Alex will die before she reaches it.
ucsaint
My query is this.

In the twin paradox let's assume that one twin Barbara keeps on moving at a relative speed of "c" away from the stationary Earth twin Alex.
If I were to be able to be at both Barbara's rocket and the Earth at the same instant ( meaning I could travel through space instantaneously ) would I actually see any difference in the ages of the two twins.

Which then gives rise to the question
Lets say we on Earth know this planet XEON to be 20light years away from us.
Lets say we have a twin on Earth Alex and another twin Barbara moving at speed of light "c" towards the planet and away from earth.
Lets assume the twins meet at an event "p" on the surface of earth. At that event both twins are of the same age and exactly same physical condition. From this event "p" onwards Barbara is moving towards the XEON, while Alex stays behind on earth.
A doctor has give both Alex and Barbara 10 years to live from event "p"

Now Alex knows that he will die in 10years and so will Barbara . I assume he can claim that there is no way Barbara can reach the planet XEON alive since she will take 20 years but she will be dead in 10years. Is it possible for Barbara to reach planet XEON alive or will she die before she reaches it ?

In special relativity, "instantaneous travel" is ill-defined, since instantaneousness is reference frame specific.

It is quite possible for Barbara to reach the planet alive, if her spaceship is fast enough. If she has a really fast ship, she can make it there and back to Earth. Of course, by the time she gets back, at least 40 years will have passed by Earth's clock and Alex will be long dead.

Suppose Bob and Alex are both stationary on Earth. We know that though Barbara is moving at high speed away from us, because we know that both Alex and Barbara should describe physical law in the same way, their reference frame relative to Bob should be different:
Standing on view of Bob, Bob counts time in the same way as Alex so if Alex knows he dies after 10years, Bob also know that Alex dies after 10 years.
However, according to relativity principle,Bob ,who can't distinguish whether he moves away from Barbara or Barbara away from him, would change his reference to describe Barbara's life.

Bob can choose like this:
1.) using (ct,x,y,z) to describe a moving Barbara and using (ct,x,y,z) to describe Alex
2.) he can choose (ct',x',y',z') to describe a stationary Barbara and use (ct,x,y,z) to describe Alex
Notice that these description should deal with infinisimal region and should concentrate on one reference frame in each description only

If Bob chooses 2.), he can describe the matter easily.
Think about that if Barbara and Alex and Bob are at rest on Earth, Bob sees that they die at the same "time".
But now the 2nd method requires him to describe Barbara dies after N years,not equal to 10,in the proposed problem. And he says that Alex dies after 10 years ,the same. He cannot say they die at the same "time" anymore, but he can say they die at the same way or same format as his description.

Last edited:
Thanks all for the reply, I think I have got my answers. Its basically the simultaneity of events that was confusing me.

## 1. What is the Twin Paradox?

The Twin Paradox is a thought experiment in physics that explores the effects of time dilation on twins who are separated and then reunited after one of them has traveled at high speeds.

## 2. How does the Twin Paradox relate to Barbara reaching XEON alive?

In this scenario, Barbara is one of the twins and XEON is a distant planet. The question is whether Barbara can reach XEON and return to Earth alive while the other twin remains on Earth.

## 3. What is time dilation and how does it affect the Twin Paradox?

Time dilation is a phenomenon where time appears to pass slower for an object moving at high speeds compared to a stationary object. In the Twin Paradox, the twin who travels at high speeds will experience less time than the stationary twin due to time dilation.

## 4. Is the Twin Paradox a real phenomenon or just a thought experiment?

The Twin Paradox is a thought experiment used to illustrate the concept of time dilation in special relativity. While time dilation is a real phenomenon, it is difficult to test in a real-world scenario with humans due to the high speeds needed to observe its effects.

## 5. Can the Twin Paradox be resolved or is it a paradox?

While the Twin Paradox may seem like a paradox at first, it can be resolved by considering the perspective of the two twins. From the perspective of the twin who travels at high speeds, their own clock will appear to be ticking normally while the other twin's clock will appear to be ticking slower. This resolves the paradox and is consistent with the principles of special relativity.

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