If you go to space for 50 years and you come back will everyone you know be old,but you wouldn't have aged?

Question

I remember hearing somewhere that if you want to go, for example, to mars it'll take hundreds of years, but you won't age and when you come back everyone you know will be old or dead. Is this true?

Answer 1

What you've heared of would be time dilation according to the special theory of relativity.

This depends on the speed at which you travel, and only has a notcable effect of your speed is really high.

At speeds that can be realistically attained for a spaceship with current technology, you wouldn't notice a thing.

At about one tenth of the speed of light, you'd start actually noticing an effect

The closer you get to the speed of light, the stronger the effect will be, asymptotically approaching a point where no time would seem to have passed in the spaceship if it had travelled at the speed of light.

Answer 2

Traveling to Mars, using the most efficient trajectory (i.e. a Hohmann Transfer orbit), takes around 260 days. Once there, you'd have to stay for another 455 days before the planets are properly aligned for a return trip, which takes another 260 days. So round-trip Earth to Mars requires roughly 980 days.

If you to travel to Mars, when you came back you'd be 2 3/4 years older. And you'd discover that everyone on Earth is also 2 3/4 years older.

The effect you're vaguely misremembering is called time dilation, and it was predicted by Albert Einstein in his theory of special relativity. As an object approaches the speed of light, its mass increases, its length contracts, and time slows down. The effect is only noticeable for velocities close to that of light. At 99% the velocity of light (0.99 c), for every day traveled, 7 days would pass in the rest of the universe. But at 10% the velocity of light (0.10 c), for every day traveled only an extra 7 minutes would pass everywhere else. On the trip described above, the max velocity reached is only 7.2 km/s, which is 0.000024 c; time dilation effects would be negligible.

Suppose you had a spaceship with a warp drive, like in Star Trek. You wouldn't have to take the most fuel efficient route, you could just point yourself at Mars and poof you're there. If your spaceship can do 0.99 c, the trip takes 2 minutes. Observers on Earth will tell you it took 13 minutes. You're watch is 11 minutes behind everyone's watches on Earth. On longer voyages, the differences in time would be more pronounced. A round trip to a star 10 light years away on this same spaceship would take two months from the passengers' perspective, but folks at home would have waited 20 years for their return.

However, it's unlikely we'll ever be able to build such a ship. As I said earlier, Einstein's theory also predicts that mass increases as objects approach light speed. The energy needed to accelerate a ship to such velocity goes up exponentially. In real life, only very tiny things - namely subatomic particles and photons- can reach such speeds.

Answer 3

HaHa...this is an example of confusing science fiction stories with reality...

If "you" go to space for 50 Years, and return on the first day of the 51st year, you will be 50 years older yourself because that is how long you have been alive, and your internal clock has been running along just like nothing has changed from your life on Earth.

When you arrive back on Earth, all of your friends and associates will also be 50 years older because of the same thing, and it is normal for us to all speak together about time in relation to Earth Time, Earth Days, Earth Weeks, Earth Months, and Earth Years.

Science fiction novels suggest that in space travel, were you able to travel faster than the speed of light, you might move into the future...get ahead of time, as it were. Mankind is not anywhere close to achievement of that possibility. So, plan on getting old just like the rest of us, at about the same time that we do.

Answer 4

I've read through the first half dozen answers and I'm afraid they are not quite satisfactory.

Part of what you heard is absolutely wrong, but there is some kernel of truth on which it is based.

One, you WILL age. If you travel in space, and roam about, exploring for 50 years, when you are finished, you will be 50 years older. However, depending on how fast YOU travel, those left behind on Earth will have aged a bit faster, relative to you. You don't have to travel at the speed of light for this phenomenon to have occured.

Einstein thorized that time is experienced differently for those moving at a high rate of speed, relative to the point of origin. In fact, this has been proven by scientists by placing atomic clocks on sattelites, and measuring their VERY accurate rates and comparing them to atomic clocks left on Earth. The faster the rate of travel, the greater the difference. This difference has been measured with rates of speed in the tens of thousands of miles per hour, much less than the speed of light.

A trip to Mars will only take several months, and, even at interplanetary speeds, when the astronauts return, the age differences, compared to someone left behind will be very negligible, perhaps only a matter of minutes or days. But for a potential explorer, travelling to the near stars, moving at large fractions of the speed of light, a 50 year trip for them may seem like a journey of hundreds of years to those of us on Earth.

I can't explain the science of it, since the calculations involve mathmatics of a sort much too complicated for me, but the mere fact that the theory has been proven is, for me, very exciting.

Answer 5

ye, you dont age as much whilst in space, so if you spent 50 years in space, you would come back to earth only 40 years older or something... you have to quite far away from earth for this to work though, is you are in earths orbit the change will not be noticeable.

Answer 6

Not exactly... You must travel away at relativistic speeds (speeds that are a considerable fraction of the speed of light) and return before you would notice this effect of Einstein's Relativity Theory. You wouldn't have to go that fast to get to Mars in a reasonable amount of time, it's not THAT far away.

Answer 7

depends how fast you're going. Time slows down when you are in motion - relative to people who aren't in motion, that is - even if you're just on an airplane. Of course, in the case of a train or an airplane, we're only talking millionths of seconds. But if you were approaching the speed of light, then time would, in fact, slow down dramatically, and you wouldn't age as quickly, relative to the folks on earth.

Answer 8

Only if you're traveling at or near the speed of light, which is a little less than 300,000 miles per second.

Answer 9

im not an expert but i'm sure the people would be dead.50 to 100 years is a long time. life expectancy doesnt reach 100.

Answer 10

Using modern space travel technology you would age the same as those you left behind on earth. Aging is not controlled by your being on Earth, it is a measurement that is universal.