[HolgerL]

Renate asks about time-travel forward in time in a thread down below.
I would like to ask:

If time-travel will be possible sometime, how come we don't get visitors from the future, today?
Isn't the fact that noone is visiting us the best proof of the impossibility of timetravel?

[Tormod]

Well, Stephen Hawking has a neat answer to this one: he says that one reason may be that it will not be possible to travel further back in time than to the date when the time machine you travel with was created.

For example: If I create a time machine today, it will always be possible to travel back and forth in this time machine - but not further back than today.

How far you could go in the other direction, though, I know nothing about. Perhaps until the day it is taken in by the feds due to tax evasion on behalf of the owner? ("We have uncovered an anomaly in your bank account - it has grown by $1 per day for 40,000 years and we would like to take a closer look at this strange machine of yours."). But then he can quickly enter the machine, go back and fix his problems...

Tormod

[anonymous]

Here is a question I found hard to give a reply , I am still without an answer , it went on the lines like this=

If you had a spacecraft that could travel at light speed or faster then which way would you point your ship if say you wanted to travel to the future or back in time

Would you then come back to a rich stephen hawkings after depositing a single dollar for him after 40,000 years or would you still have a dollar to invest for say stephen hawkings

[anonymous]

assuming you're serious...

General relativity permits time travel in the forward direction only. The spatial direction of the traveller is irrelevant, but as the velocity of the traveller approaches c, time slows relative to the 'stationary' reference frame. This means that one way time machines already exist; any astronaut that has flown on a high speed space craft has travelled into the future, albiet by a small fraction of a second.

Of course, there are exceptions to every rule. Kip thorne has popularized an application of General relativity which through the use of a wormhole where one end is stationary and the other in motion, creates a tunnel to the past. I personally disagree with Thorne, primarily because he ignores the necessity of matter moving THROUGH dimensional space to create time dilating effects. His model moves space through space, which should create no net dilation.

In terms of reverse time travel, I think this would much more likely be accomplished by creating a specialized gravitational field that reverses time flow with intensity. Also, there is some promising research in optics that utilize q. mechanics for reverse time travel.

[kilduh]

How would we know if someone visited us from the future? Some how I don't think they would be announcing it and if they did the nearest asylum is probably where they are. Or is it
will be or have been?

[kilduh]

I'm afraid I would have to disagree with the VERY esteemed Mr Hawking. You can't travel back in time by isolating an object and then making it go back through time.You must isolate the object from the universe and the make the universe go back in time.(Or at least the local area.ie the distance light travels in a year times the number of years you want to travel back in time. Apply the measurement you get to a spheres radius.That's a local area.) Somewhat energy intensive but works without paradox and violates no laws of physics.

[Noah]

Although there is some contraversy as to whether we can actually travel backwards in time, I saw something that said (assuming we can travel backwards) even if people from the future traveled backwards in time, we could not see them, but they could see us. I am not sure about all the details of this theory, but it was neat.

Noah

[6unofabitch]

<< How would we know if someone visited us from the future? Some how I don't think they would be announcing it and if they did the nearest asylum is probably where they are. Or is it

will be or have been? >>



Good point. That guy with the big red alcoholic face that sits in the park and talks to his shoes all day just might be a time traveller who was driven to drink and madness by a society that would not believe...

[Eugene]

Forget about it, gang! Time is not a dimension....just a tool for describing a specific relationship between mass, distance and velocity. "Mmmm...goo good..." - Homer Simpson
Eugene

[CD27]

for one thing, if anyone went through time, it would always change history, because someone just seeing you could make them change their mind and then they could make a bad decision and do something they wouldn 't have done if they had just not seen you in the first place. but another thing, i don't belive that when people time travel they use a machine to do it. i belive that they use their very own brains and minds to do it. here, let me tell you my theory on the subject, it is a copy and paste of a forum i posted on www.physicsforums.com


<DIV class=smallfont>space and time travel with the mind </DIV>
<HR style="COLOR: #d1d1e1" SIZE=1>

<DIV>Recently, I went through a sort of "stage" where i wanted to disprove everything worth disproving, and we all know, if you move one card at the bottom of a stack, you change quite a bit. What i did was try to figure out the atomic theory structure. I wanted to see if it was right. I came up with the conclusion that it has to be missing something, to have as many flaws as it does. And in the process of doing that, i ran across an amazing discovery, it is yet to be tested, to even be true or not, i have absolutely no mathematics to it, i myself am no mathematician, but i have a good understanding in physics. I belive i have figured out how to time travel with the mind inside you. Now, if you dont belive in the spiritual dimension, turn away now, because this theory revolves around the belief that there is one. And i dont want anyone getting "angry" because i belive something they do not, that is pure ignorance. Ok, i was trying to figure out where the connection of the physical and spiritual worlds were. It is obviously there, somewhere, because our spirit is able to control our physical body and yet be a "spirit" at the same time. This means that is connected to the physical world through a hole structure and not a solid structure. Put it this way, if you take a crochet blanket: the holes will represent inol energy (i will explain inol energy in a minute) and the solid lines represent the physical and spiritual worlds. the inol energy, in the crochet blanket, works in small groups and not as one whole, so if you were to try and control them in this state, you could only control one at a time. While on the other hand, if they were like a comforter blanket, it acts as a whole and you could control them all as one large group of inol energy. Now, let me explain what inol energy is exactly. I was trying to understand the atomic structure, but it just didn't fit right with me. Negative and positive charges, attraction and repulsion, they just didnt mix together. I discovered that without some force to push the electrons away from the protons it would cause a catostrophic end of the atomic structure, and i didn't want to see that. Some people tell me that it is the force of the electron's high speeds that holds it away from the proton. That is false, electrons can not move that quickly without causing a constant electrical disturbance, and from what i can see, i dont get electricuted constantly, do you? I didn't think so. I aggree, the electrons move relatively fast, but not fast enough to overcome the laws of electrical forces. Yea, it's a simple idea, but if they were even able to move fast enough to keep from falling into the atom, well they would end up colliding with each other and we would see little electrical "pops" in mid air all the time, but we dont. So i thought id try and fix the problem. My solution said that electrons have negative charges (which we already know) and that all negative electrical charges ONLY repel, never attract. Well that goes completely against what i was taught in high school. So i had to fix that as well; i belive i have. I included the inol force, from inol energy. Inol energy has no time or particle intervention. Basically the element of time travel. In ANY electrical charge or force, which ever direction the inol energy is flowing is also where the electrical forces flow. Now this