## Could traveling at high speed pay off financially back on Earth?

Hypothetical Space/time perception concept with financial implications.

If you were to invest a $100,000 in an account with 3% annual interest, how much interest would you have accrued in$ if you were to travel at 80 % the speed of light directly away from earth for 1 year, and then directly back to earth for 1 year at the same speed? How much time would have went by on earth?
 You age 2 years, Earth ages 3. http://www.1728.org/reltivty.htm At the bottom of the page is a calculator. Enter .8 and press c=1 to see the time dilation factor.

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 Quote by drbanner Hypothetical Space/time perception concept with financial implications. If you were to invest a $100,000 in an account with 3% annual interest, how much interest would you have accrued in$ if you were to travel at 80 % the speed of light directly away from earth for 1 year, and then directly back to earth for 1 year at the same speed? How much time would have went by on earth?
At 0.8c, gamma = 1/√(1-0.82) = 1/√(1-0.64) = 1/√(0.36) = 1/0.6 = 1.666 or exactly 5/3. Since you are gone 2 years, 3.3333 years will pass on earth. Assuming that the interest is compounded three times a year at 1%, you will end up with $110462.21. By the way, if you had stayed on earth, with the same compounding, you would end up with$106152.02 so you have $4310.19 more by taking the trip but I doubt you will get any bank to honor your claim unless the bank goes with you. Recognitions: Gold Member ## Could traveling at high speed pay off financially back on Earth?  Quote by ghwellsjr At 0.8c, gamma = 1/√(1-0.82) = 1/√(1-0.64) = 1/√(0.36) = 1/0.6 = 1.666 or exactly 5/3. Since you are gone 2 years, 3.3333 years will pass on earth. Assuming that the interest is compounded three times a year at 1%, you will end up with$110462.21.
Which would be WAY less than it would cost to make the trip
 Blog Entries: 1 Recognitions: Gold Member Science Advisor Another obvious point is that even if you make the example more extreme: Put X dollars in a Trust with with 'reliable' management company, travel such that after one year of your time passes, 100 years of earth time passes. You come back and have lot's of dollars - but probably not so much more in spending power than when you left. If you instruct that you want minimal risk of decrease, the best you can hope for over the long haul is a little better than inflation.

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Worse yet, I just got a notice from one of my financial institutions warning:
 The law in California states that any financial account that's been inactive for 3 years must be reported and may be claimed by the state as an "abandoned account."
So you better not try this in California.

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 Quote by ghwellsjr Worse yet, I just got a notice from one of my financial institutions warning: So you better not try this in California.
Many states have such a law. That's why I mentioned a Trust, managed e.g. by a Bank's trust department. It is completely exempt from such laws. FYI: even in states with such a law, if you set up online access to your account and simply check the balance periodically on line, that counts as 'activity' for the purposes of such laws (at least in my state it does; we ran into this issue in one account). The big issue for a long term investment is management that is both competent and free of conflict of interest, and must be a corporate entity with successor policies, else you are at great risk over a very long time window.
 Recognitions: Gold Member Now there's an interesting problem: how often would you have to contact your bank while traveling on a spaceship to make sure they got a call from you every three years (so as not to lose your funds)? For this particular scenario, when would the traveler make a call so that it arrived at the bank after three years?

 Quote by ghwellsjr [..] if you had stayed on earth, with the same compounding, you would end up with $106152.02 so you have$4310.19 more by taking the trip but I doubt you will get any bank to honor your claim unless the bank goes with you.
I don't follow this - the bank simply counts the number of bank years, and it has to honour that obligation. However, not only the trip will cost much more, there's also inflation.-
 Recognitions: Science Advisor No discussion of this topic would be complete without a reference to "The Theory of Interstellar Trade" by Paul Krugman: http://www.princeton.edu/~pkrugman/interstellar.pdf

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Quote by harrylin
 Quote by ghwellsjr [..] if you had stayed on earth, with the same compounding, you would end up with $106152.02 so you have$4310.19 more by taking the trip but I doubt you will get any bank to honor your claim unless the bank goes with you.
I don't follow this - the bank simply counts the number of bank years, and it has to honour that obligation. However, not only the trip will cost much more, there's also inflation.-
You're right, I don't know what I was thinking concerning the need for the bank to take the trip. Thanks for catching this.

But what about my question for the need to contact the bank every 3 years? When does the traveler need to send a message to the bank so that it will arrive 3 years after he leaves?

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 Quote by ghwellsjr You're right, I don't know what I was thinking concerning the need for the bank to take the trip. Thanks for catching this. But what about my question for the need to contact the bank every 3 years? When does the traveler need to send a message to the bank so that it will arrive 3 years after he leaves?
Just have the traveler set up a trust, problem avoided.

 Quote by ghwellsjr You're right, I don't know what I was thinking concerning the need for the bank to take the trip. Thanks for catching this. But what about my question for the need to contact the bank every 3 years? When does the traveler need to send a message to the bank so that it will arrive 3 years after he leaves?
Your time is 2 years. Earth time is 3.3333 years. All shorter intervals will have a similar ratio.

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 Quote by Nugatory No discussion of this topic would be complete without a reference to "The Theory of Interstellar Trade" by Paul Krugman: http://www.princeton.edu/~pkrugman/interstellar.pdf
Very witty, even hilarious, thanks for sharing this.

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 Quote by PAllen Just have the traveler set up a trust, problem avoided.
Too late, the traveler already left and got a communication from his bank, along with the first interest credited, sent four months (1/3 year) after he left that he had to communicate at least every 3 years to satisfy the state. Now the question is, when will he receive the message and when will he need to respond in order for the reply to get to the bank at the three year deadline?

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Quote by DaveC426913
 Quote by ghwellsjr But what about my question for the need to contact the bank every 3 years? When does the traveler need to send a message to the bank so that it will arrive 3 years after he leaves?
Your time is 2 years. Earth time is 3.3333 years. All shorter intervals will have a similar ratio.
If you are saying that he can send the message 1.8 years after he left, it will be too late, the state will already have his funds by the time he gets back.

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 Quote by phinds Which would be WAY less than it would cost to make the trip
Not according to Paul Krugman:
 Quote by Nugatory No discussion of this topic would be complete without a reference to "The Theory of Interstellar Trade" by Paul Krugman: http://www.princeton.edu/~pkrugman/interstellar.pdf
Competition will have driven the travel costs to zero. (You gotta read the paper.)