So how does everyone feel about time travel? Do you think it exist or is it possible? Do you believe it should be created? Would it even be worth investigating?



Personally I dont think it exist or will ever exist. There are way too many paradoxes and falicies. If somehow time travel was possible I would think its only possible through different parellel dimesions. If you go back in time it would never be the same dimesion that you were at and changing something there wouldnt exactly change anything in the next dimesion you may travel to. I dont think you would ever even end up in the same dimesion you left from. I think the closet to time travel we will ever get to is from now until the next second.

This is a very interesting topic (to me). If it is possible, it won't happen for hundreds of years because our technology is not sophisticated enough to make some of the time-travelling theories come to fruition. It would be really interesting to go back in time to see how life on Earth began.

According to conventional theories and physical laws, we are only able to travel further into the future. The past is out of the question unless you start in with the theorhetical like parallel, string, and matrix universes and dimensions.

Originally posted by lex400sc
According to conventional theories and physical laws, we are only able to travel further into the future.

Put another way, all we can do is waste time more quickly. :D

Originally posted by bitkahuna
Put another way, all we can do is waste time more quickly. :D

. . . . . like getting all riled up arguing continuously in this forum ? ;)

All i need is to be able to go back in time for one day (even for one hour) and come back. I would be a very very rich man the next day.

Tomorrow's lottery results from across the country would come in really handy. :D

Wouldnt be very ethical though now would it? lol

That kinda brings me to the "should time travel be created" because you can do a whole lot by going back into time by a day. Theoretically, going back in time could result in all kinds of things. Yea you can get the lottery ticket but the same numbers wouldnt necessarily come up because from what we know it could be a different parallel universe with different lottery numbers. Which means trying to warn a country about a war before it happens wouldnt always helps since that same war doesnt have to happen that day or even happen at all. Personally I think its unethical to time travel (at least back in time, if possible). If travelling back in time is possible it will most likely be through different parallel universes so it wouldnt really matter to us but the other universes would suffer from it. But then again on the other hand it wouldnt really matter since going back in time wouldnt even affect us and if that person tried to go back into the future it would most likely be in a different universe so, again, would have no affect on us.

you can go both forward and backwards in time in certain ways. you can't do it like the back to the future way where everyone is still doing the same thing at that time in another dimension, but you can use space/time to travel backwards or forwards if you were going fast enough.

100 milion years ago a star exploded, the light wont reach us until 200,000 more years and THEN we know it has happened. to us, it just happened, to the star it happened millions of years ago. if you start a journey towards the light at 10,000 light years per second you will reach it fairly fast. you have just witnessed a star explode.

Now, turn around and outrun it to the next galaxy and watch it explode again. you have just rewinded time. now run back to earth and watch it explode again (provided you eat healthy and plan to live 200,000 more years ) now you have rewinded time 3 times in a row and seen the same event unfold 3 times.

time / distance / speed

i can travel around the earth at the exact pace one rotation takes staying at 4:32 PM for one whole day. did i just make time stand still?

Originally posted by O. L. T.
if you start a journey towards the light at 10,000 light years per second

This violates Special Relativity; No object with any mass can achieve the speed of light.

Originally posted by O. L. T.
i can travel around the earth at the exact pace one rotation takes staying at 4:32 PM for one whole day. did i just make time stand still?

Time, as you describe it, is nothing more than a human construct by which we measure and quantify our experiences and memories. By travelling at over 1000mph (or the speed of Earth's rotation), you are not stopping time or causal events; you're just moving very fast.

Did anyone catch the show Elegant Universe on PBS lately? It's about string theory and how it is supposed to unify Einstein's relativity and quantum mechanics. The show was three hours long and discussed the various theories behind the universe, I found it to be quite thought-provoking. Here's the link to the site: http://www.pbs.org/wgbh/nova/elegant/ It discusses the nature of strings, how it relates to atomic particles, and how 10 dimensions are required for this theory to work.

Back to the discussion about time travel. Well, time is the 4th dimension in our universe. What is meant by "dimension" is a freedom of movement. We have the freedom to move on an X, Y, & Z axis (back/forward, left/right, & up/down), i.e. three dimensions. The fourth freedom of movement is time, we can exist anywhere on the X, Y, Z axis, the only difference is when we are at that specific point. Time measures our degree of freedom through duration. I am on the point 0,0,0 at 0 time, I was at the point 3,1,2 four minutes ago. Although minutes are not something tangible, it is a standard of duration based on the time it takes for an atom to release energy (atomic clocks). It may seem that time is constant and cannot be changed because it is only a unit of measurement to describe duration. Well, Einstein showed otherwise through his theories of relativity.

It all goes back to the situation where a person on a train, which is moving at 50 mph, throws a ball at 20 mph. The person on the train sees the ball as moving at a rate of 20 mph, but a person standing to the side of the tracks will see the ball moving at 70mph because of the combined speeds of the train (50 mph) and the ball (20 mph). The problem arises when light is used instead of a ball. Light always travels at 186,000 miles per second. If a person moving on a train, which is traveling at 180,000 mps (an assumption of course), he will observe the light travelling away from him at the rate of 186,000 mps. But the person standing next to the tracks will not see the light travelling at 366,000 mps (the combined speeds of 180,000 mps and 186,000 mps) because light always travels at 186,000 mps. So what gives? Speed= distance over time (60 mph= 60 miles / 1 hour). The speed of light remained the same at all times (186,000 mps). The speed of light remained the same to each observer no matter how much distance they travel. Therefore, the only thing that must have changed is time.

So, the person on the train who turned on the flashlight is moving slower in time because the speed of light must move away from him at 186,000 mps no matter how fast he is moving. The person standing next to the train would not suffer any time dilation (slowness). If the train stops and the person gets off, he would notice that he is in the future because when he was on the moving train time slowed down for him. Therefore, time is something more than a unit of measurement, it can be bent (slowed down).

Well, movement forward in time is theoretically possible, but practically there is not enough energy in the universe to move us at the speed of light because mass increases exponentially as you get closer to the speed of light.

Originally posted by 93LexoGS300
Back to the discussion about time travel. Well, time is the 4th dimension in our universe. What is meant by "dimension" is a freedom of movement.

There are at least three workable definitions of time in physics. That is only one ;). Time isn't always necessary to fit a model of the universe. A universe without time can exist.

Originally posted by 93LexoGS300
Although minutes are not something tangible, it is a standard of duration based on the time it takes for an atom to release energy (atomic clocks). It may seem that time is constant and cannot be changed because it is only a unit of measurement to describe duration. Well, Einstein showed otherwise through his theories of relativity.

As you said in your last sentence, time is never a constant. Time is relative. Time is different for everyone.

Originally posted by 93LexoGS300
The problem arises when light is used instead of a ball. Light always travels at 186,000 miles per second. If a person moving on a train, which is traveling at 180,000 mps (an assumption of course), he will observe the light travelling away from him at the rate of 186,000 mps.

Wrong, he will not see the light travelling away from him. If he is travelling the speed of light (which is impossible), he will see no light from the flashlight. He is travelling at the same speed at which the light is and thus the light never approaches his eyes. This negates the rest of your argument.

Originally posted by 93LexoGS300
The person standing next to the train would not suffer any time dilation (slowness).

Time dialation is caused by gravity, not relativity.

Originally posted by 93LexoGS300
If the train stops and the person gets off, he would notice that he is in the future because when he was on the moving train time slowed down for him. Therefore, time is something more than a unit of measurement, it can be bent (slowed down).

You are explaining relativity, however the difference is negligible. If someone lived on a near earth satellite for their entire life, they would age slower than the rest of mankind, but only by a few minutes over their entire lifetime.

Originally posted by 93LexoGS300
Well, movement forward in time is theoretically possible, but practically there is not enough energy in the universe to move us at the speed of light because mass increases exponentially as you get closer to the speed of light.

This experiment was conducted many many times at CERN (a particle accelerator in Europe). They were able to push subatomic particles up to 99.99% the speed of light, but no matter how much more energy they pumped into the particle accelerator, the particle absolutely would not travel the speed of light. We are talking SUBATOMIC PARTICLES here. Forget something the mass of a grown man!!!

The only way you would be able to travel into the future is to hitch a ride onto a double-wormhole. A natural wormhole is tapered at one end by a singularity, which would annihilate your existance upon your destination. If you ride a wormhole, you can cover more distance than light can (not the same as travelling faster than light though), essentially because the definition of distance is redefined in wormholes. However, travelling back into time introduces all sorts of violations (ie: conservation of energy, causality), so it is for all intents and purposes impossible.

Originally posted by lex400sc
Wrong, he will not see the light travelling away from him. If he is travelling the speed of light (which is impossible), he will see no light from the flashlight. He is travelling at the same speed at which the light is and thus the light never approaches his eyes. This negates the rest of your argument.
Not true. The speed of light is always the same (186,000 mps). If you are moving near the speed of light (assuming this is possible), light will move away from you at 186,000 because it is always constant. The only thing that changes is time, and time would slow down.

I think that something got mixed up, you argued that the guy would not see the light because he is travelling near the speed of light. But, that is not right because light always travels away from its source at 186,000 mps no matter how fast the source is moving. That's why time must slow down, hence the negation of this argument:

Originally posted by lex400sc
Time dialation is caused by gravity, not relativity.

***

Originally posted by lex400sc
You are explaining relativity, however the difference is negligible. If someone lived on a near earth satellite for their entire life, they would age slower than the rest of mankind, but only by a few minutes over their entire lifetime.
This is correct if the traveller in orbit did not come close to the speed of light, but my arguments were about a train where a person was travelling near the speed of light, hence a significant difference in the amount of time that passes.

Originally posted by lex400sc
This experiment was conducted many many times at CERN (a particle accelerator in Europe). They were able to push subatomic particles up to 99.99% the speed of light, but no matter how much more energy they pumped into the particle accelerator, the particle absolutely would not travel the speed of light. We are talking SUBATOMIC PARTICLES here. Forget something the mass of a grown man!!!
Uh, I did mention mass:

Originally posted by lex400sc
mass increases exponentially as you get closer to the speed of light.

There is one subatomic particle in the universe that theoretically travels faster than light, it's a tachyon. This is only a theory that scientists posit, even though it is no proven.

Originally posted by lex400sc
Wrong, he will not see the light travelling away from him. If he is travelling the speed of light (which is impossible), he will see no light from the flashlight. He is travelling at the same speed at which the light is and thus the light never approaches his eyes. This negates the rest of your argument.

Time dialation is caused by gravity, not relativity.
A source for the argument that light always travels at 186,000 no matter how fast the source is moving, therefore the person would be able to see the light from the flashlight.

"No matter how you measure it, the speed of light is always the same.
Einstein's crucial breakthrough about the nature of light, made in 1905, can be summed up in a deceptively simple statement: The speed of light is constant. So what does this sentence really mean?

Surprisingly, the answer has nothing to do with the actual speed of light, which is 300,000 kilometers per second (186,000 miles per second) through the "vacuum" of empty space. Instead, Einstein had an unexpected—and paradoxical—insight: that light from a moving source has the same velocity as light from a stationary source. For example, beams of light from a lighthouse, from a speeding car's headlights and from the lights on a supersonic jet all travel at a constant rate as measured by all observers—despite differences in how fast the sources of these beams move.

Light in motion
The Special Theory of Relativity is based on Einstein's recognition that the speed of light does not change even when the source of the light moves. Although it might seem logical to add the speed of the light source and the speed of the light beam to determine the total speed, light does not work this way. No matter how fast Einstein rides his bike, the light coming from his headlight always moves at the same speed.

STATIONARY LIGHT
Light from a stationary source travels at 300,000 km/sec (186,000 miles/sec).

MOVING LIGHT
Light from a moving source also travels at 300,000 km/sec (186,000 miles/sec).

Speed of light 300,000 km"

-American Museum of Natural History http://www.amnh.org/exhibitions/einstein/light/constant.php
****

"The Special Theory of Relativity.

Light is special, in that all observers in constant motion relative to somebody else will see exactly the same speed for light in vacuum.

This postulate screws up space and time totally. If everyone is to see light as going 1 billion km/hr then everyone has to be measuring different space lengths and different time durations to get the velocity of light to come out so that everyone gets the the same 1 billion km/hr value.

Nobody can perform any experiment to show any differences in physical phenomena when they are traveling at constant speed relative to somebody else.

The laws of physics stay exactly the same when the observer is in constant motion, no matter how fast that motion is. If something blows up in a constantly moving frame of reference then all constantly moving frames of references will see the same thing blow up.

These two postulates essentially imply that whenever you move relative to someone else you enter into a distinct temporal universe. You will measure time differently from the other person and you will measure lengths differently from the other person. Things, however, will conspire in such a way that everybody will measure exactly the same value for the speed of light. Things will also conspire to never allow causes to precede effects. Special relativity preserves the causality of all situations." http://scholar.uwinnipeg.ca/courses/38/4500.6-001/Cosmology/SpecialRelativity.htm

Therefore negating:

Originally posted by lex400sc
Time dialation is caused by gravity, not relativity.

93LexoGS300 ya I was watching that show a couple nights ago but missed some of it. It was very well done and is worth watching if anyone is interested in all the different theories about the universe. Logically, from what we know about time travel and how it should work it cannot exist. We are probably looking at it the wrong way because we only run into more and more paradoxes and falicies the more we research it. The only real way to gain more knowledge about time travel would be, well go into the future :egads:

The only real problem I see with time travel is finding the energy to even be able to use it. We would not only need an enormous amount of energy but enough to keep going at a constant rate. That would be a big problem. I dont think I would want to run out of "gas" while travelling through time and suddenly stop and be crushed into a singularity. That would probably not feel too good. Even if we dont need the energy to create a time machine I dont think I would want to be the first to try out a worm hole either. From what we know travelling through a worm hole will take us somewhere but without knowing where we could end up in some distant part of the universe floating in space and then imploading. The other end of the worm hole doesnt necessarily have to go through time itself but could take you through time faster into another part of the universe. So instead of travelling in a spacecraft for 3 light years you can take a worm hole to that location in under a few seconds. Then again we dont know enough about that to know it would even work. Just because there is no singularity in a worm hole does not mean we wont die but does not imply we will live either. But then again we dont have enough proof that worm holes even exist so just about every means of time travel dont exist as of yet.

Originally posted by lex400sc
This violates Special Relativity; No object with any mass can achieve the speed of light.



Time, as you describe it, is nothing more than a human construct by which we measure and quantify our experiences and memories. By travelling at over 1000mph (or the speed of Earth's rotation), you are not stopping time or causal events; you're just moving very fast.

i disagree. especially with the mass v/s speed of light. but overall just disagree. but you have gotten so used to arguing, it's fruitless to persue. just like when you respond to this :)

All I know is that I will not be the one who invents/discovers time travel. Because I've always thought that if I did, I would go back in time to when I was a young child and tell myself that "YOU WILL INVENT TIME TRAVEL!" And I don't remember that event happening to me as a child.

Originally posted by O. L. T.
i disagree. especially with the mass v/s speed of light. but overall just disagree. but you have gotten so used to arguing, it's fruitless to persue. just like when you respond to this :)

That's a humorous way to dodge quantum law. Let's see, you disagree with the theory of special relativity, which can predict the behavior of every known and measured particle in the universe. I'm left to assume that you must have the unified theory, which has elluded physicists for centuries!