# Homework Help: Spcaetime problem

1. Aug 13, 2011

### athrun200

1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

I am not sure for part a and part e. Especially for part e, without the initial distance, how can I find the time?

Can you also help me to check whether my answers are correct?

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2. Aug 13, 2011

### vela

Staff Emeritus
Your initial work is unnecessary for answering part (a). The problem states that "transmission produces a Samantha identical to the original in every respect"; in particular, that means she's the same age when she is transmitted from Earth and when she is reassembled on Zircon.

Your answers to b, c, and d are correct. Your work for part (e) completely misses the mark. I'm not sure what you're doing there.

3. Aug 13, 2011

### athrun200

In fact I don't know how to complete part e, I just try sometime seem possible.
Can you help me with part e?

4. Aug 13, 2011

### vela

Staff Emeritus
Part (e) is asking the same question as part (b). What's the difference between the two cases?

5. Aug 13, 2011

### athrun200

They are different.
In part b, the object doesn't move, however in part e, it does.
So the time taken to reach the destination in part e is longer than part b, and the question is I don't know how long does it take.

6. Aug 13, 2011

### vela

Staff Emeritus
Did the time taken to reach and return from Zircon affect how much Samantha aged?

7. Aug 14, 2011

### athrun200

Oh... I understand now thanks

8. Aug 14, 2011

### vela

Staff Emeritus
Do you? The answer to (e) isn't 1 year if that's what you're thinking.

9. Aug 14, 2011

### athrun200

Why?
The time taken to reach and return from Zircon won't affect the age, I think.

It seems it is very difficult for me...

10. Aug 14, 2011

### fleem

Unchanged data doesn't "age"

Questions (a) through (d) include no relative velocities, so the Lorentz transform is unneeded and the solutions are simple.

Question (e) makes it clear that the transporternaut sees local clocks advance by one year, therefore that transporternaut ages one year. Since that is what the question asks, the Lorentz transform is unneeded there, also.

11. Aug 14, 2011

### vela

Staff Emeritus
Oops. Yes, fleem's right. Sorry, athrun, I misled you.

12. Aug 14, 2011

### athrun200

Oh thank everyone!
By doing this question, it seems I can get a conclusion.
Everythings move in speed of light do not age.

It is correct?

13. Aug 15, 2011

### fleem

Correct.

Not only that, but in this case even if the data moved slower than light one could argue that it does not age, because the data (presumably) does not change.