Next Generation Emulation banner

1 - 20 of 32 Posts

·
Registered
Joined
·
789 Posts
Discussion Starter #1
a thread about the time travel theory ... here my point of view tell me what yah think according to this text
So how long to Andromeda at 1g using Newton's theory? We will add the condition that we wish to stop when we get there, if only to turn around and come back. The best time we can make is achieved by accelerating for the first half of the journey and decelerating for the second. The total time for the trip can be calculated to be some 2,065 years. Rather a long time really. Consider the same journey in an Einsteinian Universe. We now have a limited maximum speed (the speed of light), which at 1g is reached in 30,000,000 seconds, or a little under 354 days. After we reach this speed, how much longer will it take to reach Andromeda? The answer is no time at all! For the distance to Andromeda will have shrunk to zero for the spacecraft. However to the people back on Earth a considerable length of time would pass: some 2.2 million years
OK all well and good but I think this is flawed because I don’t think speed has anything to do with time travel why? if I ride my bike to work rather than walking I am going faster I arrive quicker I don’t go forward in time. Time doesn’t go any faster or slower for me. if someone was walking and I was riding they would have to meet me there and they would arrive after me but i haven’t went backwards of forward in time.... k so what does that mean if i traveled at let say light speed to get to a planet let say it takes 12 years at light speed but at our current speed it would take 1000 years or whatever the fact is back on earth 200o years would not have passed 12 years would have passed, like my bike journey I get there in 8 minuets the walker gets there in 35 minuets. 8 minuets have passed not 35 minuets i haven’t skipped time...
Superman spinner the world round faster wont change time as well it would just make day and night quicker but time itself would remain the same but time as we know it would change. What are your thoughts...?

I think we could go back in time or forward in time if we found a black whole nothing else maybe.... :???:
 

·
Knowledge is the solution
Joined
·
7,168 Posts
You need to expand your horizons a little Raiden. The counterexamples you are using are only micro scaled, so you shouldnt see any significant difference at all... but lets use some example that I read in Brian Green's The beautiful universe, an example that can even apply to our micro Newtonian universe :)

Consider a train that is in motion. In one of the carts, you are standing while throwing a rubber ball up and down. Now, consider an observer that is watching you throwing the ball from outside the train. Now lets see this. For you, the ball is only traveling an up-down travel(aka in the y axis). However, for the observer the ball is both traveling up and down(y axis) AND advancing alongside the train (x axis) So, for the observer the ball is traveling a greater distance in the same time, while for you the ball is just going up and down(a smaller distance) in this amount of time. Hence for the observer the ball is traveling FASTER through time-space. (yay, relativity)

It's just a small example but it gives space for some discussion :)
 

·
Wind, Life, Eternity
Joined
·
1,331 Posts
Raiden01 said:
so what does that mean if i traveled at let say light speed to get to a planet let say it takes 12 years at light speed
When you are travelling at light speed, distances shrink to zero, so you can get to anywhere in no time :lol:
And time does slow down if you travel faster.
 

·
Registered
Joined
·
789 Posts
Discussion Starter #5
our perseption of time does but the time itself stays as it is. no light speed isnt no time to go anywhere becuase a stars light can take 300 years to reach us....
 

·
Knowledge is the solution
Joined
·
7,168 Posts
It took 300 years(hey, thats a close star :D) from OUR perception, then again if you were the ray of light itself you would reach Earth in no time. Again, the absolute time (if such a thing exists, and even if it did its useless because there is no one to perceive it :p) remains the same, however, the object perception, the relative one, do varies dramatically
 

·
Registered
Joined
·
1,576 Posts
As far as I have understood, time is a broad concept, yet litterly implying nothing but passed-, current-, and moments to come. Timetravel is purely fictional to me, as it would require you to defy its untouchable rules. All that can be changed is our perception on the passing of time, which does not involve timetravel at all.

Proto pretty much said it all.

I think absolute time does exist, but only in the way of the passing of moments. If it did not, then would it not be feasible to recall events that had already happened?
 

·
Registered
Joined
·
252 Posts
this relates to time but in a different way , I once stood perfectly still for what seemed like a second but when I looked at the clock 30 minutes passed . I guess future time travel is possible but I believe past time travel is not .
 

·
Registered
Joined
·
91 Posts
It's also good to keep in mind that time is not a definite rule. Time is merely a concept created by humans to mark the progress of events.

As I recall it, there was an experiment on the subject of relative time. By placing two clocks, completely synchronized, on two different air planes, and had them travel around the world at different speeds. Once they landed, the clock on the plane that went at a higher speed was lagging behind.

Personally I don't believe that travelling back in time will be possible, but discoveries have been made in science before, that shook our very understanding of the universe, and it could very well happen again. As for going into the future, going by the "speed of light = no time" argument, one could indeed 'travel' into the future.
 

·
Registered
Joined
·
10,223 Posts
the perception of time is subjective depending on the speed an object is moving, that object will also physically age slower, but actual time still does not change

the thing is that the speed of light is a constant speed... i remember watching on cosmos and example of this where carl sagan presented the following example or something similar to it (i have to use more words since this is only text)

okay... say, two objects are trying to reach one point, they are an equal distance away from their target... object a is travelling at the speed of light, object b is travelling at the speed of light, plus 100 km an hour... which one reaches the destination first?

the answer is they both reach it at the same time. The speed of light cannot be added on to, it is a constant
Einstein's causality theory states that causes must naturally occur before effects

there is a bit of talk about light pulses which can travel faster than light, and some say that these light pulses actually reach their destination before leaving their starting point ... this however does not occur naturally, and these light pulses cannot be used in any way for our purposes

why is the speed of light important to time travel? well time slows down FOR US as we reach that speed (approx 300,000km/s) unfortunately unless we get very close to that speed it isnt even noticable... the speed of light is a very important mesuring tool because like i mentioned before it cant be added on to, our sun, and all the other suns in the universe as far as we know emit light at the same speed regardless of the speed at which they are moving, so naturally, if it cant be added on to we could see it as a maximum limit for natural speeds, if we cannot reach or exceed that speed we cannot reach nor go back in time

As I recall it, there was an experiment on the subject of relative time. By placing two clocks, completely synchronized, on two different air planes, and had them travel around the world at different speeds. Once they landed, the clock on the plane that went at a higher speed was lagging behind
yes that was part of einsteins tests

if I ride my bike to work rather than walking I am going faster I arrive quicker I don’t go forward in time. Time doesn’t go any faster or slower for me.
time actually would travel a tiny micro bit slower for you but nothing noticable, you arent exactly traveling the speed of light there, plus, you forget that you also need to add the speed at which the universe (or atleast our solar system) is expanding at, and the speed at which our planet spins around its axis and around the sun, BUT, even with all those speeds added on we do not travel anywhere near the speed of light and therefore nothing is noticable

I think we could go back in time or forward in time if we found a black whole nothing else maybe....
nobody can be sure what happens in a black hole but even so you'd be dead (crushed into a micron) before you got anywhere near it

the thing about a black hole is that it is an extinct star, the only difference is that unlike red dwarves, electric forces didnt stop its compression, and unlike neutron stars, nuclear forces didnt stop its compression, nothing apparently stopped its compression, so it compressed fully onto itself and with its extremely high gravitational pull, it just adds more density into itself as time goes by
 

·
Wind, Life, Eternity
Joined
·
1,331 Posts
Raiden01 said:
our perseption of time does but the time itself stays as it is. no light speed isnt no time to go anywhere becuase a stars light can take 300 years to reach us....
We observe the star light to take 300 years, but the star light took no time to reach us.

klatch said:
I think absolute time does exist, but only in the way of the passing of moments. If it did not, then would it not be feasible to recall events that had already happened?
Time and space is related so it makes 4D with components x,y,z,ict. (this is the last thing I remember from my physics class :()

And there's some theory about blackhole that says things getting pulled in by a black hole can only go in 1 direction (toward the center of black hole) but can move through time. It's like we go in 1 direction in time (foward?) but can go through space.
 

·
Registered
Joined
·
10,223 Posts
I think absolute time does exist, but only in the way of the passing of moments. If it did not, then would it not be feasible to recall events that had already happened?
hmm, kinda relates to the causation theory that causes must preceed events ;)

anyways, even if we managed to find a new planet to live on, then came back to earth to rejoice and be famous, everyone on earth that we knew would be dead (hell all life on earth may be already dead) so that is quite a depressing fact, if we ever go star searching, its a one way trip with no turning back, so dont forget your socks or anything
 

·
Registered
Joined
·
839 Posts
There's another theory I was reading about in a book that shows how at the beginning of the universe the speed of light may have actually been faster.
 

·
Registered
Joined
·
157 Posts
this thread reminds me of john titor.

does time really exist? to me no. time is a concept created by man. so my answer would be no to time traveling. if time traveling is possible why couldn't the people from the future travel to the past and prevent disasters?and don't say it would change their time because it won't(something to do physics)not sure though, but i read somewhere that if you traveled to the pass and shot your mother before you were born you would still be alive.
 

·
Registered
Joined
·
1,576 Posts
WindHydra said:
We observe the star light to take 300 years, but the star light took no time to reach us.
I'm not sure if I understand. The initial reflection of a just initiated light needs to "travel" (speed of light?) before reaching a destination, doesn't it? Seeing how I don't think you can deny the passing of moments (things that were, are no longer), even light takes its "time".

Strider said:
hmm, kinda relates to the causation theory that causes must preceed events ;)
I suppose my every thought relates to it until convinced otherwise.
 

·
Okama Way!
Joined
·
352 Posts
all very enlightening - kind of destroys the prospect of star trek though, or at least the propect of going home after "seeking our new worlds"

about the going back and shooting you mother thing - I think you still live because at that time (when you shoot your mother) you are still there even though in the future you (or a younger version of you) would never have been born. But sinse the prospect of time travel we are saying here is based entirely on light speed travel going back in time should be imposible while going forward (at least relitavely) should be.
 

·
Registered
Joined
·
789 Posts
Discussion Starter #17
as i said befour how can speed have anything to do with it. even tho i wasnt travaling at light speed. mabie i have just been watching too much star trek lol. also about the clocks on the planes clockes are a man made object to measure time... so there are many reasons why it could be lagging behind....
 

·
Registered
Joined
·
10,223 Posts
being three dimensional beings it is hard for most of us to understand concepts that go outside the box ;)

ive mentioned carl sagan before (he was a scientist/physicist who used to work for nasa) heres a bit from an interview he did a while ago about this subject

NOVA: As a physicist, what do you make of Stephen Hawking's chronological protection conjecture [which holds that the laws of physics disallow time machines]?

Sagan: There have been some toy experiments in which, at just the moment that the time machine is actuated, the universe conspires to blow it up, which has led Hawking and others to conclude that nature will contrive it so that time travel never in fact occurs. But no one actually knows that this is the case, and it cannot be known until we have a full theory of quantum gravity, which we do not seem to be on the verge of yet.

One of Hawking's arguments in the conjecture is that we are not awash in thousands of time travelers from the future, and therefore time travel is impossible. This argument I find very dubious, and it reminds me very much of the argument that there cannot be intelligences elsewhere in space, because otherwise the Earth would be awash in aliens. I can think half a dozen ways in which we could not be awash in time travelers, and still time travel is possible.

NOVA: Such as?

Sagan: First of all, it might be that you can build a time machine to go into the future, but not into the past, and we don't know about it because we haven't yet invented that time machine. Secondly, it might be that time travel into the past is possible, but they haven't gotten to our time yet, they're very far in the future and the further back in time you go, the more expensive it is. Thirdly, maybe backward time travel is possible, but only up to the moment that time travel is invented. We haven't invented it yet, so they can't come to us. They can come to as far back as whatever it would be, say A.D. 2300, but not further back in time.

Then there's the possibility that they're here alright, but we don't see them. They have perfect invisibility cloaks or something. If they have such highly developed technology, then why not? Then there's the possibility that they're here and we do see them, but we call them something else—UFOs or ghosts or hobgoblins or fairies or something like that. Finally, there's the possibility that time travel is perfectly possible, but it requires a great advance in our technology, and human civilization will destroy itself before time travelers invent it.

I'm sure there are other possibilities as well, but if you just think of that range of possibilities, I don't think the fact that we're not obviously being visited by time travelers shows that time travel is impossible.
I find his last point quite likely ;) maybe we're not swamped by futuristic time travelers because we've already destroyed ourselves before we can get that far in technological advances
here's the interview
http://www.pbs.org/wgbh/nova/time/sagan.html

i'd also recommend his documentorial series "cosmos" to anyone who wants to learn a little more about the universe, its a 13 part series so if you dont have the time dont bother ;)

and heres a little bit of all this crushed more into layman's terms ;) http://science.howstuffworks.com/time-travel.htm

they also make mention to time being the 4th dimension forming the space-time continuum where if the universe is affected in some way so must time be and vice versa
 

·
Knowledge is the solution
Joined
·
7,168 Posts
does time really exist? to me no. time is a concept created by man. so my answer would be no to time traveling. if time traveling is possible why couldn't the people from the future travel to the past and prevent disasters?and don't say it would change their time because it won't(something to do physics)not sure though, but i read somewhere that if you traveled to the pass and shot your mother before you were born you would still be alive.
So for you time is just a concept that exists upon the existance of a being that perceives it? If that's so, you could as well say that space is senseless if there is no one to observe it. As much as we are tied to relative concepts, absolute measures do exists (again, its just that for our level they arent practical), which would result in an absolute time (just the passing of events) and an absolute space
 

·
Retired
Joined
·
8,882 Posts
I've written about this subject several times... I'm getting tired of it :p
Nightwolf's Time Travel Thread has lots of my posts explaining several details of the underlying physics. You should check it out.

There's a very good book, written for the laymen, about time travel called Time Travel in Einstein's Universe: The Physical Possibilities of Travel Through Time , by Richard Gott III. Gott avoids the usual hype regarding the subject, and goes straight to the physics. He gives a fairly good account of the subject, IMO, and provides a good bibliography in the end.

Let me bring back a few of my old posts here, and I'll make some new considerations. Here we go:

From this thread you have the following:

Boltzmann said:
Time travel is by itself a great subject. I've read Gott's book "Time Travels in Einstein's Universe" and it's very helpful in clarifying the subject.
I believe the past is bound by a Cauchy horizon so it would be impossible to come back before time machines become feasible (far, far in the future). Or maybe Gott is right in his paper entitled Can the Universe Create Itself? and time travels were possible only in the beginning of the universe and now our entire future is bound by a Cauchy horizon.
If you want to see an interesting site that uses the time travel theme to get money look at: http://www.timetravelfund.com/
In a nutshell: it asks you for ten dolars. They'll put your money into a fund, and thanks to compound interests you'll have more than 40 billion dolars in 500 years. Sounds promising, not? :lol:
Boltzmann said:
Someone quoted Stephen Hawking about time travels, but I should warn that the quotation used was before Kip Thorn's work in black holes, worm holes and time travel. As I've said before, maybe our past is bound by a Cauchy horizon, so we cannot visit it (and travelers from the future cannot come here). Only after time travels are allowed the time-period will be available to time-travelers (e.g. after the first time-machine is built).
Personally I don't believe time-machines will be feasible in the next 5 thousand years (just a figure of speech), given the EXTREMELY HIGH requirements to create a distortion (like a rip) in time. And maybe our entire history is bounded by a Cauchy horizon in the beginning of the universe. If this is the case then time travels are impossible, period.
Boltzmann said:
>>BTW.I'd belive that you move faster than light you'd move faster than time and therefore distort space and time allowing you to move backwards in time

In a certain sense, if you travelling faster than a photon than you're going back in time (you can return before you've ever left). The problem is: no one can travel faster than light (according to Einstein's relativity).
I know that many of you've heard about tachions, so you'll think that I'm wrong. But I must put two objections against tachions:

1. They're hipothetical particles, no one has ever seen a "real" tachyon. They're allowed as some solutions to Gordon-Klein equations in general relativity.
2. Even though one tachyon could theoretically travel faster than light it could never transmit information faster than light locally. Furthermore, we have the problem of Cerenkov radiation with ever-accelerating transcedental tachyons.

But there is a way to circumvent this: worm-holes. This is not the place to go into detail about the physics of worm-holes, and there are many good books about worm-holes (e.g.: Gott's, Thorn's, Hawking's, Krauss'). Any kind of time-travel solution using worm holes must involve exotic matter (with negative energy), so it's currently imposible (we don't even know if such exotic matter exists). And all this will fail in the end if we're bounded by a Cauchy horizon in the beginning of the universe (I've said this three times by now).
Boltzmann said:
As far as the physicists today know time-travel via worms would not break any known laws of physics (nor would exotic matter or chargeless tachyons). Worm holes would be the only safe method of time-travel, but they would require HUGE (and I mean HUGE) ammounts of matter (on the order of 10^26 g/cm3) to create an adjustable time machine. Natural stable worm holes can have lesser requirements, but you would never know where you would be taken.
But as Paul Dirac has stated in 1928, given the laws of quantum physics everything that's not explicitly forbiden will happen, given a reasonable amount of time (and space).
Boltzmann said:
First, it's true that Maxwell's eletromagnetism equations (they are four diferential equations) are time-symmetric (all physical laws are time-symmetric under the CPT-theorem). So, if the laws of eletromagnetism can't distinguish between past and future, then an electron (for example) should (in average) send half of the waves as advanced and half of them as retarded. But that's not what we observe. We see all waves being emmited towards the future.
One possible explanation, given by the physicist Richard Gott III is that the universe is bound by a region of CTCs (closed time-like curves) in the past, and the waves cannot go to the past or the universe wouldn't be self-consistent. I'll not go further into this as it gets too full of math.
The other possibility was given by Nobel prize winner Richard Feynman and the physicist John Wheeler (yes, the one who gave black holes their name). They say that particles do emit waves in both directions, but they rebound in the past and their past versions then send a half wave to the future, and so on. So we observe full potentials in the present, as it's composed by today's waves and rebounds from past waves (sorry for my poor explanation, my english isn't very good, I'll try to improve this later).

And the waves going to the past aren't going FTL, they're moving at the exact speed of light. It's not as an actual time travel, as you can't send information to the past this way.
Boltzmann said:
I don't think we'll have the power of doing this kind of experiment [experiments about time travel] in this century. It requires an enormous ammount of energy, so it's not feasible with our current technology nor will it be for a long long time. In Gott's book he describes a way of traveling in time that needs the transportation of enormous amounts of mass, much bigger than an average black hole (and it's pretty dense, believe me).
The only way we could be messing with time travels would be if we find a naturally stable euclidian worm-hole (which many physicists believe is impossible, but not all - see Kip Thorn and Stephen Hawking in their recent works).
Maybe five hundred years in the future... who knows??
^^^^^^^^^^^^^

klatch said:
I think absolute time does exist, but only in the way of the passing of moments. If it did not, then would it not be feasible to recall events that had already happened?
You cannot recall past events because our particular arrow of time is determined by the transformation of negentropy into entropy . Time is just another dimension, according to general relativity (that it: 3 dimensions of space plus one time dimension). Our brains have just evolved in a way to cope with the dynamics of our low-entropy patch in the universe.
According to several scientifically sound theories, you could actually travel in time, as long as some requirements are satisfied (read my posts above). Finding a traversable wormhole would be a sure way of doing the trick ;)
 
1 - 20 of 32 Posts
Top