Time travel?

[Quasmo]

This is weird, I was thinking about this when I went to sleep list night. I believe that time travel to the past is not possible, If someone was going to do it in the future, they would have already come back in time, but you must not rule out time viewing. I believe that time travel to the future is possible, by simply slowing time around you until you reach the future, but you could never go back.

 

[silverpig]

Originally posted by: Quasmo
This is weird, I was thinking about this when I went to sleep list night. I believe that time travel to the past is not possible, If someone was going to do it in the future, they would have already come back in time, but you must not rule out time viewing. I believe that time travel to the future is possible, by simply slowing time around you until you reach the future, but you could never go back.

What if time is infinitely divisible? Even if it isn't, we know of the Planck time (~10^-42 seconds) so why should we assume that someone has come back to our exact point in time? If we assume that there ARE other timelines, then it should be safe to assume that a timeline progresses at each point in time (doesn't make sense there...). That is to say that you can travel back to any point in time you want and there will be something there. So there are 10^42 of these to choose from for every second the universe exists, multiply that by another factor of 10^15 or so for the age of the universe and you've got 10^57 possible instances to travel to. Why would you expect a future time traveller to pick our exact instant over some other?

 

[SonicIce]

I dont really understand time travel. I mean, if you were ot go back in time, you wouldn't know that you even moved, right? Would your mind be in the same state that it was when you left, or would it be how it was in the point in time that you just traveled to? So time travel is like you get in a box and everything in the box goes back in time and you'll see yourself in the point in time that you went to? Wouldn't that mean that you wouldn't exist in the point where you left from?

 

[imported_Sasha]

Originally posted by: Cattlegod
you can't go backward in time, you can only go forward at different speeds. from time being frozen to extremely accelerated time.

When I was younger I thought of a 'time bank'. This is where I could 'skip' portions of time like taking a nap and waking up some time in the future, but to the nap-taker it was instataneous. This would allow nidividuals to great extend the amount of time they existed.

Let's say that you time-banked one hour each day. At the end of the year you aged 365 days minus 365/24, saving yuo 4-1/6%. So, if you would have lived for, say, 100 years without banking time you could conceibeably extend that to 104 years.

Of course, using Special Relativity you would accelerate yourself away from a point-origin. Time dilates and if you had a twin staying at the origin they would seem to be 'older' upon your return. The speed for which you traveled plays a function for this dilation, as is the length of travel. {Talk about gonig back a few years to college}

But, the idea of a time bank would be interesting if noe did not need to travel using SR, but instead found a form of stasis. I can imagine periods of inactivity that I wouldn't mind not aging through, and instead use the stasis, or other non-SR process/means to extend my stay.

Oh, I do have plans for living for 150 years, but my original desire was 1500. Technology just isn't meeting my needs these days.

 

[Chaotic42]

Originally posted by: silverpig


What if time is infinitely divisible?

Wouldn't time being infinitely divisible wreak havoc with calculations?

 

[neospwn]

it would be impossible for 1 reason. something can't just appear or it would cause serious problems. think about it, if you were just to apear in 1 spot instantly, what about the physical matter occupying that space ( air mulecules, etc,) since you are appearing instantly,it would not have time to shift away.

 

[rubix]

well when you bring string theory into the equation isn't time travel in both directions possible on the quantum level with all those little dimensions and weird occurances?

on the non-quantum level time travel to the past is definately not possible for many reasons mentioned here already. it is possible to the future but not in any spectacular way like "poof" and you're 1000 years in the future. i always imagine the only practical way would be freezing yourself cryogenically and waking up later, which is a hack.

 

[Diademed]

Originally posted by: ReiAyanami
<BR>time is generally regarded as the 4th dimension, and all first 3 dimensions are traversable in both directions, so why not the 4th as well. although quantum scientists say there are 10-12 dimensions total but then things get real loopy.

Time is not the 4th, I believe. I think it's the 5th, or maybe the 6th......

 

[imported_jb]

so does that mean that the answer is:
Yes you can travel to the future by cyrogenically freezing yourself and travel thru space at near light speed for 1000 years and when you come back, it will be like 1001 years later ?

 

[HVAC]

What do you think memories are?

But you are asking whether you could travel back in time and observe/interact with yourself or others. I would say that it is theoretically possible but not practical. Like a man swept away by the current of a strong river, we will continue to move forward through time, unable to paddle backwards against the unrelenting and infinitely wide current.

Only an external force could dislodge us from the stream, and even then we would have perception problems, having lived our lives in a certain direction and speed since...forever.

Let's get transporter tech figured out first, then we can worry about the impossible.

 

[cquark]

Originally posted by: Diademed

Originally posted by: ReiAyanami
<BR>time is generally regarded as the 4th dimension, and all first 3 dimensions are traversable in both directions, so why not the 4th as well. although quantum scientists say there are 10-12 dimensions total but then things get real loopy.

Time is not the 4th, I believe. I think it's the 5th, or maybe the 6th......

If you're talking about conventional special and general relativity or quantum field theory, then he's right that time is considered the 4th dimension. While spacetime is curved in general relativity, it's not curved through an extra dimension.

 

[everman]

Originally posted by: jb
so does that mean that the answer is:
Yes you can travel to the future by cyrogenically freezing yourself and travel thru space at near light speed for 1000 years and when you come back, it will be like 1001 years later ?

You wouldn't even need to freeze yourself. Just travel at 0.999999999999 the speed of light. In one day of traveling at that speed(from the perspective of the traveler inside the ship), nearly 2000 years will have passed on earth. I'm not sure if you'd want to travel for 1000 years, that would = 730,000,000 earth years I think. That's kinda a long time

 

[silverpig]

Originally posted by: neospwn
it would be impossible for 1 reason. something can't just appear or it would cause serious problems. think about it, if you were just to apear in 1 spot instantly, what about the physical matter occupying that space ( air mulecules, etc,) since you are appearing instantly,it would not have time to shift away.

This is why time travel to the past is impossible (theoretically as of now). It's basically thermodynamics that says we can't go back.

 

[imported_jb]

Originally posted by: everman
You wouldn't even need to freeze yourself. Just travel at 0.999999999999 the speed of light. In one day of traveling at that speed(from the perspective of the traveler inside the ship), nearly 2000 years will have passed on earth. I'm not sure if you'd want to travel for 1000 years, that would = 730,000,000 earth years I think. That's kinda a long time

yeah, i had no idea what kind of time passage occured. your numbers seem a bit wrong from what i've seen, but whatever. i believe it, then next, i can't comprehend it. what is this? einstein's special relativity? does distance play a role? i mean, could we just build a human-accelerator big-ass loop in space that was like photon-powered or something? can i just mount one on the moon? what if i vibrate at 99% of the speed of light?

yeah! wtf? if it takes light five hours to get from here to pluto, why would it take only .007 hours for you if you were essentially travelling in a photon? am i wrong? it only takes .007 hours for a photon to go 5 light years? if you asked the photon anyway. i thought the speed of light meant that the photon said, "well shit! i travel at the speed of light and it still takes me 5 years to get from earth to pluto!"

 

[syconub]

yea, my new rig can do all this, AND a bag of chips. jk..

 

[imported_jb]

i liked the idea of lightspeed time travel to future at first, but not anymore.

 

[unlockthesource]

Originally posted by: mmcdonalataocdotgov
Time Travel Is Not Possible Pragmatically.<BR><BR>Proof: If time travel had ever been possible, we would always have known about it, since time travellers would have brought us the information - eventually. It would be inevitable that once time travel was known in one time, it would be known in all times (method, mode, theory, etc.)<BR><BR>Since we do not know how to travel in time, we will never know (never knew) how to travel in time.

How can you be so sure?? Perhaps roswell was an accident by some time travellors? Im not saying I believe the Roswell hype at all, but you cant be that sure. The reason being that anyone with a brain (here and now) can understand the dangers of time travel and its implications. So dont you think that humans who are a few centuries more evolved will recognize these dangers as well?

My point is that if time altering devices could be constructed, the technology would, without a doubt, be very heavily controlled and monitored. If you could create a device to alter time, you, in theory, would also need a devide that was not affected by the passage of time. That device would be responcible for detecting changes in time that are not authorized, and restoring the timeline (before it ever changed )


...i think im done here...

 

[everman]

Originally posted by: jb

Originally posted by: everman
You wouldn't even need to freeze yourself. Just travel at 0.999999999999 the speed of light. In one day of traveling at that speed(from the perspective of the traveler inside the ship), nearly 2000 years will have passed on earth. I'm not sure if you'd want to travel for 1000 years, that would = 730,000,000 earth years I think. That's kinda a long time

yeah, i had no idea what kind of time passage occured. your numbers seem a bit wrong from what i've seen, but whatever. i believe it, then next, i can't comprehend it. what is this? einstein's special relativity? does distance play a role? i mean, could we just build a human-accelerator big-ass loop in space that was like photon-powered or something? can i just mount one on the moon? what if i vibrate at 99% of the speed of light?

yeah! wtf? if it takes light five hours to get from here to pluto, why would it take only .007 hours for you if you were essentially travelling in a photon? am i wrong? it only takes .007 hours for a photon to go 5 light years? if you asked the photon anyway. i thought the speed of light meant that the photon said, "well shit! i travel at the speed of light and it still takes me 5 years to get from earth to pluto!"

I don't quite understand time dilation myself, just managed to pull together infor off various sites. I do know that it's measurable even if you had an atomic clock travelling around the speed of sound. I didn't make up the 0.999999999999 either, it's just derived with a function to measure time dilation.

 

[imported_jb]

yeah, right? some tv show was saying the .999 thing meaning an infinitly growing mass of the object. it would be increasing, but the speed of light IS a number. there probably is a maximum mass you will never reach. no great links on time dialation from what i've seen.
__
oh ok.
well i just saw a post from "cquark" maybe in the 'stability near 125' thread. according to him and the experiment he linked to, time dialation really does exist. proven with half-lives, not a clock.
so weird..
still, it means those cosmic muons take only 2.2seconds to get to earth.

 

[silverpig]

Originally posted by: jb
yeah, right? some tv show was saying the .999 thing meaning an infinitly growing mass of the object. it would be increasing, but the speed of light IS a number. there probably is a maximum mass you will never reach. no great links on time dialation from what i've seen.
__
oh ok.
well i just saw a post from "cquark" maybe in the 'stability near 125' thread. according to him and the experiment he linked to, time dialation really does exist. proven with half-lives, not a clock.
so weird..
still, it means those cosmic muons take only 2.2seconds to get to earth.

The way it works is your mass increases as you go faster and faster. As a result it takes more and more energy to accelerate the larger mass. It would thus take an infinite amount of energy to accelerate a body moving at the speed of light.

 

[imported_jb]

right, but the speed of light isn't just a theory, is it? isn't it an actual speed, like the speed of sound?
what i was saying is that it takes a certain amount of energy to go 5mph so it must also take a certain, finite, amount of energy to get to the speed of light. forgetting about the energy to keep the object at speed.

 

[theinsen1]

it is obviously NOT possible. think about it?
lets say you have your exams today,and you jump aboard the time machine to go in the future
and get the paper, but to reach there you must have passed that moment.
now that is not possible beacause you have jumped into the time machine and can never reach that piont of time no matter how fast you travel.
well any comments on this?

 

[silverpig]

Originally posted by: jb
right, but the speed of light isn't just a theory, is it? isn't it an actual speed, like the speed of sound?
what i was saying is that it takes a certain amount of energy to go 5mph so it must also take a certain, finite, amount of energy to get to the speed of light. forgetting about the energy to keep the object at speed.

You're not quite getting it... Assuming no air/water/source of drag, it takes no energy to keep something at speed. This is inertia. An object in motion will continue to move in a straight line at a constant velocity until acted upon by a force. So if you're up in space and you throw a rock at 20 mph, it'll continue to move at 20 mph forever (of course, neglecting gravity from planets/sun etc). So even if you're at 99.9% the speed of light, you'll keep going at that speed until you hit something. You don't need to keep your rockets firing in order to maintain that speed.

However, you may have noticed that it takes some energy to throw a baseball at 20 mph. You have to push it along until you let it go. You may have also noticed that it takes about 10 times as much energy to throw a bowling ball at 20 mph (assuming a bowling ball is 10 times as massive as a baseball... just guessing here). This is because the bowling ball is more massive.

Now, relativity states that as you go faster, your mass increases. So you weigh 100 kg now, but if you go fast enough your mass will be 200 kg. Because you're more massive, it takes more energy to accelerate you (baseball vs bowling ball). As you approach light speed, your mass becomes infinite. It would then take you an infinite amount of energy to make yourself go any faster. Think of it as trying to throw a baseball with infinite mass... you just can't do it.

 

[willfreund]

A common idea is if you go faster then the speed of light you can reverse time...But if you have fast light , wouldnt that mean you would never see it?

 

[imported_jb]

you did bring up some things i forgot. what i was getting at/questioning is that:
why the infinite mass? isn't the speed of light approx. 300 000 kilometers per second? doesn't that give a finite mass?
whatever... i'm getting sick of this topic..