Friday, September 09, 2005

Time Travel

Admin Note: I am moving this discussion of time travel to the main area of the blog so it's easier to access.

frankd23 said...
I would like to make a comment about the possibility of time travel. Even though the majority of people feel that it is possible, there are some that dont and I would like to try and convince you. Time travel is THEORETICALLY possible with the use of a wormhole. A wormhole is two black holes that are connected through a fourth dimension called hyperspace. It is essentially a tunnel. Now suppose we shook hands through the wormhole, and then I was to go and take a trip at speeds close to that of the speed of light. Because of Einstein's and other brilliant scientists theories, I would experience time dilation. That is, my time would pass more slowly then ur time. So what seemed like 1 year to me may have been hundreds to you. So I return to earth after my 1 year and your hundreds. It is then possible for me to step through the wormhole to where u are and be in the future, and same with u as you would be in the past. Of course I'm no expert on the topic and some of what I just explained may need a few small fixes but the majority of it should be correct. I also can't take credit for coming up with that explanation because I intially read it in Black Holes and Time Warps by Kip S Thorne (Great book I recommend it and the class). So hypothetically time travel is possible, however I dont believe we will ever achieve it through the use of a wormhole. So I hope I was able to convert a couple of you to believing that time travel is possible. If you have good arguments against what I said I'd love to hear them. But keep in my I'm argueing that time travel is possible. I am NOT argueing that we will in fact achieve time travel.

11:20 AM


Blogger Chris Tillman said...

Nigel said...
Before we attempt to answer all these questions about when time began, or if time could go backwards, we really have to get a grasp of what time really is? Does time really exist as we percieve it, or is that just the only way our minds can make sense of it? Im not at all an expert on the topic, but i have read of theories which say that time does not go chronologically as we see it. If time really is a 4th dimension, does that mean it has some sort of physical structure? I guess thats one of the main topics of the course, but i think a better understanding of time could open up a lot of doors for understanding the nature of the universe. Im not sure if there is anyway to accomplish this without complex mathematical equations or if college students could really understand the philosophical theories, but i know i would like to try. Anyone who has a greater understanding of this subject, feel free to post.

11:47 AM
Hawaii said...
Time travel could indeed be possible. However, I believe that it is only possible in one direction. This doubles with the flow of time question. The flow of time cannot be reversed. For example, if I were to go back in time to (hypothetically) retake a test. Now ignoring the fact that I would have two bodies in the room at the same time, I would conceivably get a better grade this time around. This would cause me to not need to time travel in the first place. Therefore, I would never go back in time to retake the test. So...never having gone back in time, I would once again receive a bad grade on the test. This in turn means I WOULD go back in time to remedy the problem. It creates an infinite loop of events.

Travel into the future however doesn't have these problems. You simply didn't exist in a certain time period.

12:03 PM
Hawaii said...
In respons to frankd23...the use of wormholes as a method of time travel has some problems. Einstein's theories have serious holes in them at the sub-atomic level. His equations just do not work out at this level. Quantum mechanics explains sub-atomic motions much more accurately.

Now let's take a close look at what a wormhole is:

According to this site (and I agree) a wormwhole has nothing to do with a fourth dimension. It is simply like bending a piece of paper (space) to make two points closer together. Now when you walk through the wormhole, time's speed won't change because your velocity never exceeded that of your own step (NOT on the own view). You won't BE in the future on the other side. You'll just be there before light from your previous position normally would. It isn't technically faster than light travel because the space you traverse isn't equal to the distance from one point to've just made the points really close together.

12:11 PM
frankd23 said...
In response to the rebuttal of hawaii...I will not argue that there are probably mathematical problems that are way too advanced for me to even dream about. But I still mantain that the point I made is true. I read what was written on the website that u gave, which says that using exotic matter, a wormhole can be kept open. Thus, if a wormhole is kept open and we execute the plan that I had said in my original post, we should be able to travel through time because of time dilation at relativistic speeds. I am not just talking about walking through a wormhole, the story told of a person traveling at relativistic speeds so that time dilation occurs. Also, maybe I shouldnt have referred to hyperspace as a 4th dimension. Hyperspace was created as an imaginary dimension to represent four-dimensional spacetime. The astronomy 102 website is good at explaining this.
sept. 30th slide 5 describes hyperspace and Nov 23rd describes the use of hyperspace for wormholes and retells my story better then i did. I actually believe i had it backwards when i told it. But if a wormhole is able to be kept open and one end of it travels at speeds close to the speed of light, time dilation will occur and theoretically you could go back and forth in time, but no earlier then the trip had began.

2:29 PM
chris said...
For those with some physics background who are interested in the possibility of time travel, this site may be of interest. It is more technical than anything we will discuss, but it gives a good overview of the case for the possibility of time travel with respect to modern physics.

9:34 AM  
Blogger mparent said...

First, I have a comment about the wormhole theory of time travel. This is indeed a physical possibility as already mentioned but it would require the amount of energy stored in a planet the size of Jupiter to keep it open. However, there are other less well known ideas for time travel, many of which are physically impossible. There are some involving infinitely long cylinders, traveling faster than light or other things all physicists agree are impossible. Another possibility is to make a large torus (basically a large donut) and to alter the gravitational waves within it. This could be done by moving a very massive object around it very quickly, analagous to adding a weight to a rope and swinging it around in a circle. If someone were to enter the hole in the middle of the torus they would then travel back in time to when the time machine began operating. As with every possibility of time travel you can't go back before the time machine was made. As a result we don't see future time travelers around because we haven't made a time machine yet. I'll also be commenting on Hawaii's flow of time in my next post.

1:45 PM  
Blogger mparent said...

This is in response to the flow of time question. If you work with the physical equations time is the one variable that can be made negative and still have the equations actually behave (ie. no singularities etc...). So thewre is clearly a theoretical possibility for time to flow backwards but it doesn't for reasons believed to be related to the laws of thermodynamics, primarily entropy. This basically says a closed system (presumably the universe as a whole) can only become more and more chaotic as time goes on. This is not the point though, the argument you make is that of paradoxes occuring and there have been numerous suggesstion for dealing with them.
One suggestion is simply that the future already exists, So using the test example, if in the future you chose to go back and retake the test then you would actually have your future self in the room with you the first time you took the test.
Others theorize that something would prevent your future self from retaking the test and altering the past.
Another group takes the back to the future approach of multiple parallel time lines (related to the parallel universe idea). So that when your future self goes back and changes the past the time line actually splits in two at that place. In one time line the future you didn't take the test and in the other the test was retaken.
There are countless other ideas proposed for dealing with time travel paradoxes but obviously we don't know the truth since our physics doesn't tell us and we haven't actually had anyone time travel yet.

2:00 PM  

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