The answer to time travel?

[Tiesto]

Forgive me if you think i'm crazy, i think i may have cracked Time Travel subject to a few theories which could well be wrong.

If it were possible for Nasa to put a spaceship into orbit and accelerate constantly, would this ship eventually not speed up to the point where it would be travelling faster than the speed of light hence travelling back through time, and if the ship could then land before it actually took off???? 

 

[trilobite]

No. Why would this make you go backwards in time?

Firstly, the spaceship could not exceed the speed of light ( 'c' ) as the closer it got to c, its mass and spacial dimensions would increase, and thus would require infinite energy to continue accelerating.

Secondly, time slows down with velocity. So that at high velocities, time would slow for the occupants. This means that upon their return to Earth, what seemed to them like a, say, 6 month trip would seem like a three year trip relative to those remaining on Earth.

There was a thread around here yesterday about atomic clocks, and someone mentioned that due to the accuracy of these 'timepieces' it has been possible to demonstrate that if you have two synchronised (atomic) clocks, and you fly one around at high speed for a bit, it will run slower relative to the one that remains stationary.

So, if you travelled at near-light speeds, it would, in theory, be possible to go forwards in time, relative to where you took off from. This doesn't mean you could meet yourself in the future, or anything like that, as you would not have been there in the first place to meet. (if you see what I mean) Relativity doesn't allow those paradoxes to happen.

[Tiesto]

Thanks for that, had a feeling it probably wouldn't be possible or someone would have already tried it!!

[trilobite]

Keep trying! And if you do manage it, don't forget to look me up in 1995 with a list of every Grand National winner up to 2004. Cheers!

[helghast]

someone actually has travelled forwards in time

this guy on the space station was going so fast that he actually travelled a miniscule fraction of a second into the future

but who would be bothered to work that out and how?????

[natalie_1982]

Ok,I'm venturing into unknown territory (another section I don't use!), so if this is a dumb question tell me.

 

Deamo, how do you know they travelled a fractio of time forwards if it wasn't recorded why or how?  And who did that happen to and why haven't I heard about it already?

 

Does anyone think it is actually possible to travel time then?  My boyfriend is into maths and physics, the universe and stuff like that that I don't really understand (anything other than English, food content, music and celebrities!)

[stoo_pid]

It was kind of recorded natalie_1982.  The astronaut referred to here was British-born Michael Foale.  I think he holds the record for the most time in space by a U.S. astronaut.

He was interviewed on Breakfast with Frost the other week.  He was saying that because of the speed he was travelling at in the space station & the length of time time travelling at that speed, they had calculated that time had run at a fraction of a second slower for him.

The thing is, time isn't fixed - its relative to other things, speed being one of them.  So from his prespective he will have travelled forward in time a fraction of a second because he arrived back when we were all a little bit older than him.

 

[stoo_pid]

BTW natalie_1982, it's not a dumb question.

As for the time travel thing, in theory it's not possible.  However, get a load of blokes round their mate's house after a session on the beers & the conversation will usually eventually turn to either Time Travel Theories, Star Wars or both.

 

[trilobite]

The point about my first answer was that 'moving clocks run slow' - so if I go to the corner shop and back - even on a bike, my clock has run slower relative to my wife's time (who just sat at home)

So it's not a case of ".someone actually has travelled forwards in time ...this guy on the space station " we all do it by virtue of our relative velocities in immeasurable fractions of a second. I thought my first answer implied this.

 

To all intents and purposes though, and to answer in the vein of the question, to generate a good-old-sci-fi-instantaneous-time-jump of, say, a few hundred years, would require incredibly high (near-light)speeds, so is not really possible.

[Tiesto]

Thanks Stoo-pid, i'm glad that the lads and me are not the only people in the world who try and and solve the worlds unsolveable when we've had a few!!

Funny isn't it, the things people talk about when we're drunk.

[finex]

Further to the previous questions, relativity also states that as one approaches the speed of light, the mass of an object increases exponentially. I think the idea is that an object would have virutally infinite mass before it ever got to the speed of light.

[slimfandango]

Someone talks of 'speed'. I don't know what 'speed' is, without reference to time. I want to talk to you about 'fgorg'. Fgorg is a quality of objects that makes them ferg and farg, at rates determined by feerg.

Of course, you don't know what I'm talking about yet, but could it refer to something real? Would there be any meaning to it other than the meaning I impute? My point is that we impute a quality 'speed' to something, which is the distance travelled by a certain time frame. So what the heck does it mean to then say that we can talk of this relative to time (of course time is included in its meaning) and Eineysteiney also said that the only absolute was c, the speed of light, which includes time as a part of its meaning, no? help (trilobyte/whoever). My brain hurts.

[stoo_pid]

Just back from the pub slimfandango? ; - )

 

[Tiesto]

For Fargs sake Slimfandango, my brain is hurting. Surely the speed of light can be measured as a unit of time, and why would something increase in mass if it were going faster as someone else put it.

[JohnPPotts]

Under Relativity, you could never accelerate beyond the speed of light as the energy you put into acceleration would increasingly add mass, and if you could ever attain the speed of light, your mass would be infinite. The only circumstance under which time travel might be allowed is with wormholes - however such an outcome requires matter with negative energy and any such wormholes would probably be of atomic (or subatomic) size and mere nanoseconds in longevity. A good (if slightly nerdy) book that explains some of the problems of faster than light travel is "The Physics of Star Trek" (as well as discussing how a transporter, holodeck and phasers might work) - though obviously bases its examples on a highly successful TV series! 

[Gef]

trilobite has got it backwards. If you could travel at speeds close to the speed of light you would go BACKWARDS in time. Imagine, I leave Earth at near light speed now and return one year later on my clock, ie November 2005. My clock has been running slow relative to those on Earth so more time will have passed on Earth and it will be later than November 2005. I am now in the past.

[IndieSinger]

Time travel must be possible. Busted have been to the year 3000. (Not much has changed, apparently, but they live under water. Oh, and your great-great-great-granddaughter is pretty fine... iii-iine. Although by my reckoning, she'd be roughly 2900 years old.)

[trilobite]

Sorry, gef, but the Earth has moved on since then !! ;o)

"I leave Earth at near light speed now and return one year later on my clock"

 

As for the real issue, Busted (who?) may have been to the year 3000, but Zager & Evans (Google it, kiddies) have been to the year 2525, 3535 AND 4545. Na Na Na-naa Na

(Nice to converse again, indieSinger, but do you remember 'Stump'?)

[magicdice]

Povemeister:

energy = 1/2 x mass x speed

so, the more energy you gain, the greater the speed becomes, right? however, there is a limiting top speed, c, also known as the speed of light in a vacuum (approx 300000000m/s). once this speed has been reached, it is impossible to get any faster. so speed is no longer a variable in our equation. which leaves us with energy, still increasing... 1/2 is a constant, speed has become a constant, so mass must increase

tadaaa! oh the wonders of A-level physics(!)

[stoo_pid]

Sorry Gef, trilobite has got it right.  Using your example, if you went away from Earth close to the speed of light for a while & then came back, your clock will have moved slower than one on Earth.  In other words, as you correctly point out, more time will have passed on Earth.  So from your perspective you will have come back to Earth in your future.

[Pinotage]

If time travel of the sort shown on TV films is possible, how come we don't have tourists visiting from the future?

 

On the other hand it may be possible, its just we haven't worked out how to do it. Think just how recent the creation and use of electricity is; who'd have guessed it could be made by rotating magnets in wire coils, or what can be done by using it?