is it possible to travel more than 70 light years, if the average lifespan is 70 years?

Question

The average life span in the united states is about 70 years. Does this mean that it is impossible for an average person to travel a distance greater than 70-light years away from the earth? Explain.

relativity hurts my mind. My guess is no, because you can not travel faster than light. The thing that is confusing me here I think though is that light years are a distance. Does that mean that 70 light years from the earth at rest frame is different than 70 light years from the spaceship rest frame?

clear answer for dummies would be appreciated!

Answer 1

Does that mean that 70 light years from the earth at rest frame is different than 70 light years from the spaceship rest frame?



They are the same if the spacecraft travels so slow that you can accurately solve the problem with Newtonian mechanics alone.



BUT, if relativity is significant, then no. There will be length contraction fro the spacecraft observer.



Consider 80% light speed for the spacecraft wrt Earth. Consider Earth the origin and Alpha Hydri A to be the destination.





The lorentz factor for 80% light speed is 0.6. That means, that length will contract to 60% of what it actually is in the Earth reference frame. Hence, the spacecraft astronauts will think the distance from Earth to Alpha Hydri A is only 42 ly instead of 70 ly.



Correspondingly, with time dilation, the astronauts experience 52.5 years passing.

Answer 2

No. Not possible. The traveler would be dead. Unless there were hybernation sleep



The guy will only reach about 65 light years or so (before he dies) if his space ship can travel very close to light speed. (If he could travel at light speed) 70 light years for a guy traveling at light speed is an actual 70 years experienced by the guy.



That is why in sci-fi moves they have to put people to a hybernation sleep (and because the director doesnt want an 80 year old grandpa bustin' up alien scum....it wouldnt be believable). If you could go into some sort of hybernation sleep that slowed your aging process then you would effectvily increase your life span. Making it possible for you to travel the 70 light years.

Answer 3

Pay attention to gintable's answer and then read it carefully perhaps several times until you can absorb it fully.



It's a comprehensive and excellent answer towards helping your understanding.



Don't be overly concerned about finding the topic a little mind-bending, it drives most people nuts at first This it because it flies in the face of what we may term, common sense thinking. In fact a lot of science does this.



There is a splended book, now available in paperback, at modest £8.99, to help all you students out there who find relativity a pain in the brain.



Title ....Why does E = mc^2 ? (and why we should care?)



Authors Brian Cox and Jeff Forshaw (University of Manchester professors)



ISBN 978-0-306-81911-7



I've just finished reading this and it is really brilliant. Probably the best book on the topic for some time. (amazingly you only need high school maths to get through it. So, beg or borrow one before they all sell out)

Someone out there, this might be a great xmas present for Richard our question poser.

Answer 4

Practically its impossible to travel 70 light years in just 70 years.

Answer 5

Practically speaking, no. Going anywhere remotely near the speed of light is impossible, let alone the speed of light itself. The faster you go, the more affected by gravity you are, plus, the amount of power needed is astronomical. Essentially, you would get sucked in to the nearest gravity well while speeding up.

Now, if there were some way to go the speed of light, it has something to do with the space-time continuum, therefor we are not affected by time.

Answer 6

The thing is that due to relativity as one is traveling at the speed of light, the effect of time is less for you, so 2 months of aging for you maybe 40 years for an outside observer



no wait actually at the speed of light, time stops for you but not for an outside observer

but near the speed of light, time significantly slows down for you

Answer 7

no its not possible because a light year is how far light can travel in a year moving at i think 300000 km/s ITS IMPOSSIBLE