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Time travel possible?

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  • 31-07-2009 10:50pm
    #1
    karlog
    Closed Accounts Posts: 1,563 ✭✭✭


    I remember hearing from someone that it's possible to travel forward through time by moving through space really fast. For e.g travelling round the earth close to the speed of light for minutes will result in days passing on earth or something like that. Kinda like superman, except forward in time.

    If i could explain it any better i would:o
    Tagged:


«13

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    #2
    [Deleted User]
    Posts: 4,630 ✭✭✭ [Deleted User]


    Yah, that's true. The physics behind it is very complex, but the implications are relatively easy to understand.

    There are certain paradoxes which arise, such as the Twin paradox. Having a read of that wikipedia article should explain it a little better.


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    #3
    r3nu4l
    Registered Users Posts: 17,399 ✭✭✭✭r3nu4l


    Of course, the problem we have as humans at the moment is that we haven't a hope of developing a craft that can travel at this speed. However, the concept is there, the physics and maths on paper says this form of time travel can happen so it just remains for us to see how else we can 'hack' time :)


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    #4
    Helix
    Closed Accounts Posts: 17,661 ✭✭✭✭Helix


    -JammyDodger- wrote: »
    Yah, that's true. The physics behind it is very complex, but the implications are relatively easy to understand.

    There are certain paradoxes which arise, such as the Twin paradox. Having a read of that wikipedia article should explain it a little better.

    i think he was talking about forward time travel, which is definitely possible.

    backwards time travel is still unproven as far as i know, beyond assumptions including exotic matter which is assumed to exist for the purpose of the idea


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    #5
    IRISH DAYWALKER
    Closed Accounts Posts: 114 ✭✭IRISH DAYWALKER


    to travel forward in time while travelling close to the speed of light a near infinte ammount of fuel or energy is needed, more than is on the earth at the moment!


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    #6
    HouseHippo
    Closed Accounts Posts: 1,332 ✭✭✭HouseHippo


    Yep very possible, infact we could be surrounded by travellers from the future right now as along the way to time travel its likely that scientists will have discovered the properties of invisibility!

    Think about that next time your havin a sh1t :D


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    #7
    HouseHippo
    Closed Accounts Posts: 1,332 ✭✭✭HouseHippo


    IRISH DAYWALKER wrote: »
    to travel forward in time while travelling close to the speed of light a near infinte ammount of fuel or energy is needed, more than is on the earth at the moment!
    If we were to harness that energy which I reckon would be most likely sourced from dark matter it is possible that we may cause the earth to implode so to speak...


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    #8
    Amalgam
    Registered Users Posts: 6,026 ✭✭✭Amalgam


    Is it true astronauts on the space shuttle lose or gain a tiny tiny amount of 'time', relative to people on Earth?

    What governs that, velocity\momentum\gravity?


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    #9
    HouseHippo
    Closed Accounts Posts: 1,332 ✭✭✭HouseHippo


    As far as I know its true, not sure why though


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    #10
    FrostyJack
    Registered Users Posts: 1,726 ✭✭✭FrostyJack


    Is it true astronauts on the space shuttle lose or gain a tiny tiny amount of 'time', relative to people on Earth?

    What governs that, velocity\momentum\gravity?

    It is true, as the astronauts are further away from the planet, time travels quicker, so to speak, than on the surface. They would have to be there a long time to gain any noticable time. So astronauts are affectivly the first time travellers. There is a good episode of BBC Horizon on google video if you do a quick search. Can't rememeber if it mentions this in it.


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    #11
    Amalgam
    Registered Users Posts: 6,026 ✭✭✭Amalgam


    If the past is a state of 'decay', then the past will be maybe just heat or radiation. It could be there, just not in a form that's navigable in the way science fiction portrays it.

    Ugh, the idea of 'catching up' on time, or a future of sorts.. makes me feel a bit: http://www.youtube.com/watch?v=x8w95xIdH4o


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    #12
    legologic
    Registered Users Posts: 382 ✭✭legologic


    There's also the wormhole timetravel method.

    step 1: construct or find a stable wormhole (just to make the first step easy)
    step 2: maneouver one opening of the wrmhole onto a VERY fast spaceship
    step 3: fly away in said spaceship close to the speed of light creating a time difference between the opening on the spaceship and the opening back on earth.
    step 4: jump through wormhole, congratulations you have now travelled through time!
    step 5: ???
    step 6: Profit!


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    #13
    mussha
    Registered Users Posts: 121 ✭✭mussha


    ive been try to get my head aroud the idea of time travel. is you can travel faster than the speed of light can you move through time?

    for example if i beamed a light and at the same time i set off at the faster than the speed of light and then after 1 hour i stopped the light i had turned opn an hour ago would not yet have happened where ever i was?

    if i set off aroud the world at 10 -20 times the spee of light by the time i got back to where i started would more time have passed than i would be after using whikle traveling?


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    #14
    Thoie
    Registered Users Posts: 6,344 ✭✭✭Thoie


    I'm reading Time Travel in Einstein's Universe at the moment, which was helping me understand all of this, but have now confused me with quantum vacuum states.

    It uses examples of a party invitation to Alpha Centauri that's 5 years away, and explains answers to your question quite well, but using diagrams that I'm not even going to try to replicate here :)


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    #15
    AlmightyCushion
    Moderators, Education Moderators, Technology & Internet Moderators Posts: 35,046 Mod ✭✭✭✭AlmightyCushion


    Amalgam wrote: »
    Is it true astronauts on the space shuttle lose or gain a tiny tiny amount of 'time', relative to people on Earth?

    What governs that, velocity\momentum\gravity?

    Yes. Gravity causes time to travel slower. Because there is less gravity on the international space station, time will travel quicker so any one who stays there will age quicker than they would on earth.


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    #16
    narac
    Closed Accounts Posts: 27 ✭narac


    No expert on this matter at all, but will give my tuppence anyways ;).
    mussha wrote: »
    ive been try to get my head aroud the idea of time travel. is you can travel faster than the speed of light can you move through time?

    You are always travelling through time. This is immediately obvious. Time progesses for everybody. But what you are getting at is that, as you travel at different velocities, time progresses at a different pace. This is true, and has been measured. In everyday life, it has no influence, as the difference is incredibly small, practically infinitesimally small.

    But a test was carried out where two atomic clocks were synchronised, and one was essentially flown around the earth pretty much as fast as possible (yeah I don't know the exact specifics). When the two atomic clocks were brought together, they were out of syncyh by nano-seconds (not a lot of time, but measurable).

    If you were to travel at close to the speed of light, time would slow significantly for you. This is important. Time would only slow for you. Thus, if you travelled off into space at, say, 95% the speed of light. If you travelled as such for a week, and then came back to earth, you would find the rest of the earth would have aged by years, but you would have only aged by a couple of weeks. If you travelled at the speed of light, you would experience no time passing. You could return to earth instantly, and years would have passed.

    The problem is that, approaching the speed of light takes ever increasing amounts of energy, to the point that it takes an infinitely large amount of energy to achieve the speed of light. Thus travel at the speed of light is impossible (for anything but the zero mass elementary particles, such as photons).
    mussha wrote: »
    for example if i beamed a light and at the same time i set off at the faster than the speed of light and then after 1 hour i stopped the light i had turned opn an hour ago would not yet have happened where ever i was?

    if i set off aroud the world at 10 -20 times the spee of light by the time i got back to where i started would more time have passed than i would be after using whikle traveling?

    So, yes, basically if you travel near the speed of light (doesn't need to be 10-20 times the speed of light), you would have experienced noticeably less time than thos of us who didn't travel.


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    #17
    r3nu4l
    Registered Users Posts: 17,399 ✭✭✭✭r3nu4l


    Two time travel threads merged. Very interesting discussion!! Wish I could get my head around some of the concepts out there. :)


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    #18
    PCPhoto
    Registered Users Posts: 6,584 ✭✭✭PCPhoto


    r3nu4l wrote: »
    Two time travel threads merged. Very interesting discussion!! Wish I could get my head around some of the concepts out there. :)

    whats the point in trying to figure it out....... just accept it when it becomes commercially available. :D


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    #19
    narac
    Closed Accounts Posts: 27 ✭narac


    legologic wrote: »
    There's also the wormhole timetravel method.

    I think the wormhole method is more likely to be to manouvre one end of the wormhole so that it is near a very strong source of gravity (i.e. a black hole), and have the other end in normal gravity (e.g. maybe orbiting earth or something). As AlmightyCushion said, gravity causes time to slow down, and thus causing the two ends of the wormhole to drift apart in time.

    Then you fly a spaceship into the wormhole orbiting earth, you will appear out of the one orbiting the black hole, but will have also travelled back in time.

    Easy, eh? :D
    Helix wrote: »
    i think he was talking about forward time travel, which is definitely possible.

    backwards time travel is still unproven as far as i know, beyond assumptions including exotic matter which is assumed to exist for the purpose of the idea

    Yeah, it is unproven. People have tried to prove it, but without any verifiable success.

    Basically, Einstein's theories preclude travel at the speed of light, because it would take an infinite amount of energy to accelerate any object up to that speed. However, his theories don't preclude travel at greater than the speed of light.

    In the same way that it takes infinite energy to accelerate to light speed, if an object was travelling at greater than the speed of light, it would take infinite energy for that object to slow down to the speed of light. However, if you were travelling at greater than the speed of light, then you would experience time in reverse.

    The only way for this to work would be for the object to somehow be able to instantly change it's velocity from being this side of the speed of light, to being the far side of the speed of light, without ever achieving the speed of light.

    Either that, or the object would have to come into existence at greater than the speed of light (and by that I mean the creation of subatomic particles). There is even a name used for particles that, for their entire existence, travel at greater than the speed of light. I can't remember it though.

    Anyways, people did a test to see if these particles actually exist. They knew when a solar flare was coming, so they set up sensors on the earth's ground to detect an increase in particle activity before the effect the solar flare reached the earth. Thus, if these greater-than-light-speed particles were created by the flare interacting with the earth's atmosphere (not the flare itself, but the stream of particles emitted from the sun associated with the flare), they would travel back in time towards the earth's surface, and interact with the sensors.

    It of course failed, but that only proved that these particles aren't created by a stream of solar particles interacting with the earth's atmosphere, though most physicists agree that it is unlikely that these greater-than-light-speed particles don't exist. They're kindof a by-product of a theory, rather than a physical fact.

    :confused:

    Edit: just remembered that the greater-than-light-speed particles are called tachyons, and conversely particles that travel at less than the speed of light have been grouped as tardons

    Edit: and the massless particles that travel at exactly the speed of light (e.g. the photon) are sometimes referred to as luxons :)


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    #20
    thethedev
    Closed Accounts Posts: 300 ✭✭thethedev


    I personnally beleive the concept of time travel is a proposterous notion.
    Time is just a man made mechanism for all I can see.
    I'll have to get the books out to fully understand the idea, but right now it just seems completely silly!


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    #21
    Daftendirekt
    Closed Accounts Posts: 1,312 ✭✭✭Daftendirekt


    thethedev wrote: »
    I personnally beleive the concept of time travel is a proposterous notion.
    Time is just a man made mechanism for all I can see.
    I'll have to get the books out to fully understand the idea, but right now it just seems completely silly!

    Someone can correct me on this if I'm wrong, but as far as I'm aware, time is as much a part of the universe as matter and energy, it has a beginning and probably will have an end, and is affected by both speed and gravity.

    Much more than just a human invention. Pretty mind boggling stuff all the same.


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    #22
    mussha
    Registered Users Posts: 121 ✭✭mussha


    over and over again people are saying we dont have the energy to get to the speed of light. i understand this but in theory IF we did manage it and could travel at the speed of light of faster than light what would happen?

    i was under the impression that time is a definate thing that always travels in one direction (foward) so going back in time is impossable pegardless of what speed we could go? am i wrong?

    if we could travel at the speed of light or faster would time mearly stop?
    ie if i took off in my speed of light veichle and did a lap of the earth would it be the same time when i got back to where i started?

    and if it was the same time when i got back but rater than me goin back to the excact spot i started of from ( my garage ) i went somewhere else (to the shop) would this mean i would have went from my garage to the shop in 0 seconds?
    and what would the people in the shop see me just appearing?

    is it as basic as saying that if we can travel fast enough we can stop time and teleport (travel from place to place without time passing)?


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    #23
    narac
    Closed Accounts Posts: 27 ✭narac


    This is where I become a bit hazy on the subject.
    If you travel at the speed of light, from your viewpoint, time stands still. From someone elses viewpoint, you take the length of time it takes for light to travel anywhere, i.e. you travel at 300,000kph.
    Example: a photon leaves the sun and travels towards the earth. From our viewpoint, the photon is traveling ar 300,000kps, and thus takes about eight minutes to reach us. However, from the photons viewpoint, no time passes from when leaves the sun and reaches the earth, as it is traveling at the speed of light.

    My understanding is that if you travel faster than the speed of light, from your point of view, time would flow backwards. However, from everybody else's point of view, you would still be travelling at a given speed, and thus would take time to reach your destination.
    Example: if you leave the sun and travel at twice the speed of light towards the earth, time would flow backwards for you. However, to an observer on the earth, you would still take four minutes to reach the earth, as you are travelling at 600,000kps.

    I may be wrong on this one - in fact, I probably am - but it makes sense to me.

    BTW if this were moved to the physics forum, some better answers might be got.


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    #24
    AlmightyCushion
    Moderators, Education Moderators, Technology & Internet Moderators Posts: 35,046 Mod ✭✭✭✭AlmightyCushion


    narac wrote: »
    This is where I become a bit hazy on the subject.
    If you travel at the speed of light, from your viewpoint, time stands still. From someone elses viewpoint, you take the length of time it takes for light to travel anywhere, i.e. you travel at 300,000kph.
    Example: a photon leaves the sun and travels towards the earth. From our viewpoint, the photon is traveling ar 300,000kps, and thus takes about eight minutes to reach us. However, from the photons viewpoint, no time passes from when leaves the sun and reaches the earth, as it is traveling at the speed of light.

    My understanding is that if you travel faster than the speed of light, from your point of view, time would flow backwards. However, from everybody else's point of view, you would still be travelling at a given speed, and thus would take time to reach your destination.
    Example: if you leave the sun and travel at twice the speed of light towards the earth, time would flow backwards for you. However, to an observer on the earth, you would still take four minutes to reach the earth, as you are travelling at 600,000kps.

    I may be wrong on this one - in fact, I probably am - but it makes sense to me.

    BTW if this were moved to the physics forum, some better answers might be got.

    If you travel at the exactly the speed of light then I imagine if you were to look out your windows that for the duration of your trip you would see exactly what you seen when you started your trip. Because the light that was around you when you started the trip is travelling at the same speed as you. Although that doesn't sound correct to me. As for travelling faster than light, that's quite hard to imagine. Maybe you see everything like it's in fast forward.


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    #25
    Gurgle
    Closed Accounts Posts: 5,064 ✭✭✭Gurgle


    AlmightyCushion wrote: »
    If you travel at the exactly the speed of light then I imagine if you were to look out your windows that for the duration of your trip...
    The trip doesn't have duration, you arrive instantly (subjectively).


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    #26
    AlmightyCushion
    Moderators, Education Moderators, Technology & Internet Moderators Posts: 35,046 Mod ✭✭✭✭AlmightyCushion


    Gurgle wrote: »
    The trip doesn't have duration, you arrive instantly (subjectively).
    So if I travel for a year at exactly the speed of light, to me no time has passed? This is all starting to hurt my head.


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    #27
    Gurgle
    Closed Accounts Posts: 5,064 ✭✭✭Gurgle


    AlmightyCushion wrote: »
    starting
    :D


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    #28
    AlmightyCushion
    Moderators, Education Moderators, Technology & Internet Moderators Posts: 35,046 Mod ✭✭✭✭AlmightyCushion


    Gurgle wrote: »
    :D

    Yup. Everytime a see something to do with time travel, my brain tells me not to bother with it. I'm fine for a while but it doesn't take long for something to not make a blind bit of sense to me and that's when I break down into tears and assume the fetal position. :)


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    #29
    DublinWriter
    Registered Users Posts: 9,555 ✭✭✭DublinWriter


    AlmightyCushion wrote: »
    If you travel at the exactly the speed of light then I imagine if you were to look out your windows that for the duration of your trip you would see exactly what you seen when you started your trip. Because the light that was around you when you started the trip is travelling at the same speed as you. Although that doesn't sound correct to me. As for travelling faster than light, that's quite hard to imagine. Maybe you see everything like it's in fast forward.
    Not really. Einstein's theory of Special Relativity describes how time dilation occurs between two observers when there is a significant difference in spatial velocity between them both, and General Relativity more importantly describes how space and time are not separate, but are interconnected dimensionally.


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    #30
    veXual
    Registered Users Posts: 344 ✭✭veXual


    But if you were to travel at the speed of light for a year technically would a year not pass and you would just end up in some obscure location X amount of lightyears away??

    Like Almightycushion said once timetravel is mentioned my brain just does not want to co-operate.


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    #31
    Hellrazer
    Moderators, Arts Moderators, Recreation & Hobbies Moderators Posts: 10,581 Mod ✭✭✭✭Hellrazer


    veXual wrote: »
    But if you were to travel at the speed of light for a year technically would a year not pass and you would just end up in some obscure location X amount of lightyears away??

    If you were to travel at the speed of light for exactly one year then surely you`d end up "one light year" away from where you started--no??

    Now for the confusing bit-assuming the above is true---would you age by 1 year and would you notice that year passing?

    I remember reading something that taking the above as an example ie you travelled 1 year at the speed of light (one light year) then a year would pass normally for you (the traveller) but on your return in 2 years of your time(ie travelling 2 light years) you would find that the earth had aged by a few hundred or few thousand years??

    Very confusing!!!


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