Stephen Hawkins Universe - Time Travel

Amp34 · 25 Sep 2010 at 21:04

Now, lets just ignore the really basic wording of the show and focus on one specific thing, the time travel.

I just watched it and one big thing hit me, essentially time travel would be worthless, if you could only travel forwards in time like described at the end. The big spaceship travelling at 0.99x the speed of light causes one minute on the ship to be one year on eath. That means hundreds and thousands of years will have passed before they slow down again, let alone get back to earth. Not bad on its own but getting to the edge of the galaxy this way apparently means you could do it in one lifetime (80 years). Well that's useful, because aside from those on the ship humans and potentially earth would be long gone by that point. Real life Red Dwarf apparently.

I'm sure by the time they got there there would be more "advanced" humans there, probably having set up a Butlins holiday park!

So, is time travel actually worth while?

Spektor · 25 Sep 2010 at 21:10

Amp34 said:
The big spaceship travelling at 0.99x the speed of sound causes

Impossible! not even men of the future could go faster than sound!

Castiel · 25 Sep 2010 at 21:11

I think that's "speed of light" not sound.

apeZ · 25 Sep 2010 at 21:12

I don't think it's useful, but it's very very cool.

Tefal · 25 Sep 2010 at 21:14

useful for ark ships but at that speed i doubt you'd be able to avoid obsticals (or even have computers/people process their presence and react in time to even start the manoeuvre).

Also it could be useful for certain people "leapfrog though history has it where.

one thing though does this mean it would significantly reduce the wear on the ships components?

ie they only have 80 years of run time though the engines or would the engines put in X years of undiluted run time as it were.

Amp34 · 25 Sep 2010 at 21:21

Spektor said:
Impossible! not even men of the future could go faster than sound!

Just checking to see if people were awake...

Tefal said:
useful for ark ships but at that speed i doubt you'd be able to avoid obsticals (or even have computers/people process their presence and react in time to even start the manoeuvre).

Also it could be useful for certain people "leapfrog though history has it where.

one thing though does this mean it would significantly reduce the wear on the ships components?

ie they only have 80 years of run time though the engines or would the engines put in X years of undiluted run time as it were.

I did wonder about the leapfrog idea, but in which case if we can build a (almost) speed of light ship I'm sure we will be able to build a stasis chamber, or work out how to revive people from freezers! interesting idea about the equipment, I'm assuming the engines would be on the "ship" time and so would only have 80 years on them, not the ~36.5 million years the rest of the universe/earth would have experienced in that time.

Flubble · 25 Sep 2010 at 21:23

so if i had a ship that could do this and i traveled for 1 minute away from earth then 1 minute back to earth i would be 2 years older?

doesn't make sense to me, surely i would be 2 minutes older?

Tefal · 25 Sep 2010 at 21:26

Flubble said:
so if i had a ship that could do this and i traveled for 1 minute away from earth then 1 minute back to earth i would be 2 years older?

doesn't make sense to me, surely i would be 2 minutes older?

No if you got on this ship and travel (assuming instant acceleration and deceleration) for 1 year of earth out then 1 year of earth time back 2 years would have passed on earth but for you in the ship only 2 minutes would have passed.

Castiel · 25 Sep 2010 at 21:27

Amp34 said:
Just checking to see if people were awake...

I did wonder about the leapfrog idea, but in which case if we can build a (almost) speed of light ship I'm sure we will be able to build a stasis chamber, or work out how to revive people from freezers! interesting idea about the equipment, I'm assuming the engines would be on the "ship" time and so would only have 80 years on them, not the ~36.5 million years the rest of the universe/earth would have experienced in that time.

I think your math is a little skewed. If you travelled for one year at 99% of the speed of light, seven years would have passed on earth, also the galaxy is somewhat more than 80 lightyears across so even at the speed of light it would take many, many lifetimes to traverse the Galaxy.

Tefal · 25 Sep 2010 at 21:29

Castiel said:
also the galaxy is somewhat more than 80 lightyears across so even at the speed of light it would take many, many lifetimes to traverse the Galaxy.

that's what he said the people on the ship experiencing the "slower" time only experience 80 years but the journey takes millions of years.

Amp34 · 25 Sep 2010 at 21:29

I'm taking my maths from the TV show that was just on. If that's that wrong then I have no idea. :confused:

mrk · 25 Sep 2010 at 21:31

Teddybear!

Amp34 said:
Now, lets just ignore the really basic wording of the show and focus on one specific thing, the time travel.

I just watched it and one big thing hit me, essentially time travel would be worthless, if you could only travel forwards in time like described at the end. The big spaceship travelling at 0.99x the speed of light causes one minute on the ship to be one year on eath. That means hundreds and thousands of years will have passed before they slow down again, let alone get back to earth. Not bad on its own but getting to the edge of the galaxy this way apparently means you could do it in one lifetime (80 years). Well that's useful, because aside from those on the ship humans and potentially earth would be long gone by that point. Real life Red Dwarf apparently.

I'm sure by the time they got there there would be more "advanced" humans there, probably having set up a Butlins holiday park!

So, is time travel actually worth while?

Cryogenic sleep solves that problem.

Castiel · 25 Sep 2010 at 21:34

Tefal said:
No if you got on this ship and travel (assuming instant acceleration and deceleration) for 1 year of earth out then 1 year of earth time back 2 years would have passed on earth but for you in the ship only 2 minutes would have passed.

Nope, the OPs math is way off. If you travel for one year at the speed of light (.99) then during that lightyear, seven earth years would have passed.

Incidently if you travelled for one year at twice the speed of light only 7 months would have passed, hence travelling back in time (but only in relation to your travelling time)

Tefal · 25 Sep 2010 at 21:34

Khaaan! said:
Cryogenic sleep solves that problem.

depends on if it works, if it has a time limit, side effects or if it's even possible.

Tefal · 25 Sep 2010 at 21:35

Castiel said:
Nope, the OPs math is way off. If you travel for one year at the speed of light (.99) then during that lightyear, seven earth years would have passed.

well you'll want to write to the program makers then as he's just quoting them.

where are you getting the 7 year figure from btw?

Robosapien · 25 Sep 2010 at 21:37

Amount of energy required to accelerate anything with mass resembeling that of spaceship up to that speed would be a problem.

*Haven't watched said programme

Castiel · 25 Sep 2010 at 21:43

Tefal said:
that's what he said the people on the ship experiencing the "slower" time only experience 80 years but the journey takes millions of years.

The time dilation at only 99 percent the speed of light is not great enough for that period of Earth time to have passed in relation to Ship time.

One Lightyear is the distance it takes light to travel a specific distance....Thus in 80 years ship time, only 560 years would have passed during the journey. The Galaxy (milky way) is about 100,000 light years across so light would take 100,000 years to traverse the galaxy.

To extrapolate, a starship travelling at lightspeed would also take 100,000 years to traverse the galaxy (ship time), however back on earth due to relativistic time dilation 700,000 years subjective earth time would have passed.

Narziss · 25 Sep 2010 at 21:44

Yes.

(sent 4 days from now)

LordSplodge · 25 Sep 2010 at 21:44

Flubble said:
so if i had a ship that could do this and i traveled for 1 minute away from earth then 1 minute back to earth i would be 2 years older?

doesn't make sense to me, surely i would be 2 minutes older?

It's all Relative, baby!

Go read A Brief History of Time and then you may be a little wiser...

Tefal · 25 Sep 2010 at 21:45

Castiel said:
The time dilation at only 99 percent the speed of light is not great enough for that period of Earth time to have passed in relation to Ship time.

One Lightyear is the distance it takes light to travel a specific distance....Thus in 80 years ship time, only 560 years would have passed during the journey. The Galaxy (milky way) is about 100,000 light years across so light would take 100,000 years to traverse the galaxy.

To extrapolate, a starship travelling at lightspeed would also take 100,000 years to traverse the galaxy (ship time), however back on earth due to relativistic time dilation 700,000 years subjective earth time would have passed.

write the program makers then.