Parallel universes and time travel

[issaiah1332]

Parallel universes have been a thing of the twilight zone until recently, scientists have been, more and more, starting to believe in, or at least take into consideration that alternate universes may exists. I was wondering what some of your thoughts were. And while we are on this subject what are your views on time travel.

[Ynot]

thought the multi-verse theory was pretty old don't certain quantum theories rely on the existanse of a multi-verse?

[issaiah1332]

Yes, many quantum mechanical theories revolve around the existence of parallel universes. This brings forth the theory "Everytime the quantum world is faced with a choice it divides itself to complete each choice." This has been abserved in a lab, when observing the quantum world, sceintists place 2 slits, and a particle actually divided to go into both slits. Amazing! Also, superstring theory explains lot of this.

[issaiah1332]

I was wondering (and please post, ONLY if you understand relativity) what some of your views and theories were on time travel.

[Levi1057]

aww and here I was all ready to talk about time travel.

[issaiah1332]

Awww, sorry to offend you Levi. [/quote]

[Krrish]

Time travel is possible if you can travel faster than light. For example: Start from earth now and go away to another glaxy with a speed greater than light. So you can see the light waves of incidents just happened are falling behind you. Now increase the speed very much and catch a light wave of an incident that was started from earth one year ago. Now return back to earth with more speed. You will be landing on earth with a time shift to past. If you believe in multiple universes as the M theory states, there is no need to travel to space. You can travel to another universe just around you and return back through another door. You will reach a time shifted version of this universe. Inorder to go to another universe, we dont have to travel to the boundaries of this universe. The universes are embedded within each other which I cant explain with our limited knowledge on dimensions. Consider the following. You are watching a movie in a theatre. The hero in the movie is surrounded by terorists. They will surely kill him ( It is not neo in matrix ). So what is the only chance he has to survive. " He can step out from the movie screen in to the movie house ! ". Impossible ? That is m- theory saying about multiple universes. In that way, we can travel from one universe to another, without considering distance. Now scientists are working very hard to achieve this. They are trying to send a "graviton" to another universe. I can tell more on M-theory, if you want..

[Distant Clone]

Originally posted by korothism Time travel is possible if you can travel faster than light. The speed of light is not constant. It depends on the density of the medium through which it is traveling. Consider yourself traveling through a room filled with water, and a room filled with air. I'm sure you have a higher maximum speed traveling in one room instead of the other. By the way, the M theory with doors to other universes sounds really interesting. I had a dream where I jumped into outer space and saw open white doorways in the blackness. I did not go into it then, but it's a goal of mine to do just that.

[Krrish]

I talked about the maximum speed of light 3x10^8 m/s. If we can travel faster than that, time travel is possible.

[bradybaker]

There are other ways that travelling backward in time is possible...though its much trickier than travelling forward in time. It involves the way that cosmic strings (http://en.wikipedia.org/wiki/Cosmic_string) effect the fabric of space as the travel through it...I forget exactly how it works...it has something to do with travelling around the string as it moves in the warped space it creates. By doing this, it is theoretically possible to end up when and where you started. If I can find the article where I first read this (I think it was Scientific American...like 4 years ago) I'll post it. Sorry for confusing everyone.

[Howie]

Doesn't the String theory support parallel universes. All of wich are stack on on e another? Time travel. This may sound a bit obsurd but hey. They say you cannot reach the speed of light. In space there is no restriction or force against your mass. So having said that does it not seem possible that at some point we could device a device that would gradually work up to tremendous speed. Wich would make time slow down. I think withvhe universe as big as it is that this is the only true means of time travel we can even ponder.

[Krrish]

[quote]Doesn't the String theory support parallel universes. All of wich are stack on on e another? The string theory is gone. M theory has taken its place. We can say that string theory is the predecessor of M theory. There are theoretical proofs of particles that can travel faster than light. "Tachyon" is one of them. Read the wikipedia article of tachyon. A team of researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) has successfully demonstrated, for the first time, that it is possible to control the speed of light – both slowing it down and speeding it up – in an optical fiber, using off-the-shelf instrumentation in normal environmental conditions. Read the full article .

[Howie]

Thanks korothism for the information. As you can see I am about nine issues behind on scientific American. So much to read so little memory...& time.

[WindsOfPlague]

whats the difference between Parallel universes and Alternate universes? Has the string theory changed at all after its now called the m theory?

[Krrish]

whats the difference between Parallel universes and Alternate universes?[/b] In meaning no difference. But I say \"All parallel universes are alternate universes but all alternate universes are not parallel universes\". See what wikipedia says.. If you are tossing a coin, the output will be either head or tale. But in multiverse theory we say that we will have both the ouputs and it is splitted in to two \"parallel universes\". In one universe you will be continuing with the head output and in the parallel one you will be continuing with the tale output. To know the difference between parallel and alternate consider a more detailed example. It is known as \"Quantum Immortality\" Imagine that a physicist detonates a nuclear bomb located beside her. In almost all parallel universes, the nuclear explosion will vaporize the physicist. However, there should be a small set of alternative universes in which the physicist somehow survives (ie. the set of universes which support a \"miraculous\" survival scenario). The idea behind quantum immortality is that the physicist will remain alive in, and thus able to experience, at least one of the universes in this set, even though these universes form a tiny subset of all possible universes. Over time the physicist would therefore consider herself to be living forever. Now the next question... Has the string theory changed at all after its now called the m theory?[/b] M theory generalised all the different string theories in to a single theory. It was believed before 1995 that there were exactly five consistent superstring theories. It was shown later that these super string theories were related by dualities, which allowed physicists to relate the description of an object in one string theory to the description of a different object in another theory. So scientists thought that these five theories are nothing but reflections of a single truth in "five different mirrors". So the scientists decided to find out the original theory and they discarded the mirror images. And that single underlying theory is named as M theory.

[Howie]

So what of time travel? Anyone elaborate on my thoery. Go ahead, pick it apart!

[Krrish]

Suppose you travelled back in time and killed your biological grandfather before he met your grandmother. Then you would never have been conceived, so you could not have travelled back in time after all. Now did you travel back or not? The grandfather paradox has been used to argue that backwards time travel must be impossible. Stephen Hawking once suggested that the absence of tourists from the future constitutes a strong argument against the existence of time travel. But I personally believe (wish) that time travel is possible. Here is the \"How time travel works\" article.... This is the best one available on the subject.

[andorf]

[quote] does it not seem possible that at some point we could device a device that would gradually work up to tremendous speed.. its entirely possible that such a device can be created, but for a human to travel safely at the speed of light or faster, they would have to accelerate extremely slowly.

[Howie]

Originally posted by andorf its entirely possible that such a device can be created, but for a human to travel safely at the speed of light or faster, they would have to accelerate extremely slowly. I know as a result of these speeds that time dialation is an issue. But I did not think that traveling over the speed of light was obtainable. Realisticly, half way would be a quite remarkable achievment.

[bradybaker]

Accelerating an object with mass to the speed of light is physically impossible.

[Stalker]

Originally posted by bradybaker Accelerating an object with mass to the speed of light is physically impossible. But can still take a shortcut and get a practical speed that is larger than the speed of light.

[issaiah1332]

Originally posted by korothism Suppose you travelled back in time and killed your biological grandfather before he met your grandmother. Then you would never have been conceived, so you could not have travelled back in time after all. Now did you travel back or not? The grandfather paradox has been used to argue that backwards time travel must be impossible. Stephen Hawking once suggested that the absence of tourists from the future constitutes a strong argument against the existence of time travel. But I personally believe (wish) that time travel is possible. Here is the \\\"How time travel works\\\" article.... This is the best one available on the subject. If you travel back in time you do not akter this reality, you alter someone elses, hence parallel universes.

[issaiah1332]

Originally posted by andorf its entirely possible that such a device can be created, but for a human to travel safely at the speed of light or faster, they would have to accelerate extremely slowly. But why does the speed of light have to be a factor. Remember, Einstein united space and time, so we could travel at warp speed. If we did this we can penetrate space-time, and theoretically create a wormhole.

[Krrish]

Originally posted by issaiah1332 If you travel back in time you do not akter this reality, you alter someone elses, hence parallel universes. Thank you... That was a brain refreshing trigger !

[bradybaker]

Originally posted by Stalker But can still take a shortcut and get a practical speed that is larger than the speed of light. If you're talking about using wormholes to cover vast distances in small amounts of time so that d/t > c, yes that is theoretically possible. But since the distance travelled is reduced significantly by the wormhole, in actually, d/t would still be less than c. Once again, it is physically impossible to accelerate an object with mass to the speed of light.