PDA

View Full Version : time travel



Silent Knight
2005-Feb-03, 09:53 PM
I was watching the science channel a few days ago and a guy said that it would be possible to make a time machine and as soon as it was turned on you could start receiving messages from the future. What happens if five minutes later you decide to destroy it?

Normandy6644
2005-Feb-03, 10:05 PM
I was watching the science channel a few days ago and a guy said that it would be possible to make a time machine and as soon as it was turned on you could start receiving messages from the future. What happens if five minutes later you decide to destroy it?

I suppose you wouldn't have received any messages. :D

Gramma loreto
2005-Feb-03, 10:42 PM
Was that the one trying to use an array of lasers to induce frame dragging? Interesting concept.

Sticks
2005-Feb-04, 07:18 AM
Suppose you receive a message from the future saying that tomorrow you get killed in a train crash, and you decide to take the day off so you are not on the train when history unfolds? :-?

Paul Beardsley
2005-Feb-04, 09:28 AM
So you're sitting at home playing Spider Solitaire when suddenly a train is derailed and hurtles into your house.

ToSeek
2005-Feb-04, 02:51 PM
So you're sitting at home playing Spider Solitaire when suddenly a train is derailed and hurtles into your house.

That would be impressive considering the nearest train line for me is three miles away and down the hill on the other side of a lake.

sidmel
2005-Feb-04, 03:34 PM
Well according to one 'what if' show. You would temporarily create a wave effect in the time line, creating a series of scenarios.

In the one, you never received the message. In the second a train track would have been built by your house. Maybe in another, you actually moved to a house next to a train track. The wave would then select the most likely event and time would straigten out again.

No problem!

That's why I don't check my messages anymore. :D

Amadeus
2005-Feb-04, 03:45 PM
Was that the one trying to use an array of lasers to induce frame dragging? Interesting concept.

I saw that a while back. Gave me an idea.

Say that you got a "basic" system working and you could recieve messages from a week ahead. Why dont you use the machine to send back the details of a further weeks R&D on the machine.

Could be that because of this the first message that you appear to get are the plans for fully operational machine that would have taken years of
R&D

farmerjumperdon
2005-Feb-04, 04:25 PM
Sounds way too much like Back to the Future scenes where the pictures and newspapers change before their eyes as they undo or redo history. I thought it was pretty well established that, given what we know, time dilation only occurs for objects traveling at speeds a significant fraction of the speed of light. And that it is not time travel in the sense that you can visit yourself in the future, or go back in time, or any of that hokey stuff. You experience time passing differently than someone observing from outside your inertial system. You are traveling forward in "their" time, but not your own.

Argos
2005-Feb-04, 04:36 PM
Living in such an interesting epoch, why havenīt we received any message, or visitor, from the future yet? They must have some kind of code of conduct forbidding time travel to the past...

farmerjumperdon
2005-Feb-04, 07:32 PM
Argos,

Your question, IMO, serves as a very good arguement that going back in time is not possible. If the future does already exist in some other place or dimension, (which I do not believe), and if in the incredibly broad expanse of that future, Earthlings have discovered how to go back in time, we would have certainly heard from them by now. (They might have rules against doing so, but all man-made rules get broken).

I think the whole concept gets ill-percieved simply because it is too often called "time travel." That is such a misnomer. It should be called "time dilation" or "time compression." Calling it time travel gives people the idea that it's like hopping in a car and going somewhere, just a little more complicated. Also, the examples of how dilation occurs all involve, by necessity, moving at very high speeds, again alluding to the Lets-take-a-ride-to some-other-time perception.

Time is a local and personal phenomenon. You can not jump ahead or back in time and you can only experience one timeline (your own). On the scale and in the dimensions in which humans exist, the direction arrow of time is one-way.

Moose
2005-Feb-04, 08:28 PM
So you're sitting at home playing Spider Solitaire when suddenly a train is derailed and hurtles into your house.

That would be impressive considering the nearest train line for me is three miles away and down the hill on the other side of a lake.

To rip off (and butcher) the Minbari saying from Babylon 5: "Fate manages". :wink:

Moose
2005-Feb-04, 08:36 PM
I think the whole concept gets ill-percieved simply because it is too often called "time travel." That is such a misnomer. It should be called "time dilation" or "time compression." Calling it time travel gives people the idea that it's like hopping in a car and going somewhere, just a little more complicated. Also, the examples of how dilation occurs all involve, by necessity, moving at very high speeds, again alluding to the Lets-take-a-ride-to some-other-time perception.

Actually, you'd have to travel physically as well. Suppose you jump back to the same time you'd been three months ago without altering your physical location. Congrats, you are now... somewhere... where the Earth will pass once the motion of all objects from the Earth to the galaxy are factored in.

Time shifting might be a cheap way to get satellites in orbit though. Shift the appropriate number of minutes or hours to gain altitude, then light off the engines to achieve the desired orbital velocity.

farmerjumperdon
2005-Feb-04, 08:49 PM
Depends on what you mean by "back." If you travel back to a place where you were 3 months ago, you have not necessarily dilated your time experience relative to anything or anyplace else. If you mean you travel somewhere very fast, then travel back to where you started very fast, then you may experience some time dilation; but I don't see how that has anything to do with, or in any way supports the idea of "traveling" through time. You certainly wouldn't be going backward in time. If you went fast enough to cause dilation or compression of time, you might find that people in the place you originally left have experienced the passage of a longer peroiod of time than you have.

I still prefer to think of it as having traveled, and because of the speed of travel, having also experienced time dilation relative to others. "Traveled through time" is simply not an accurate way of putting it. Could you travel under, around, over or behind time also?

Maddad
2005-Feb-04, 10:21 PM
Suppose you receive a message from the future saying that tomorrow you get killed in a train crash, and you decide to take the day off so you are not on the train when history unfolds? :-?James P. Hogan wrote an entire science fiction book, Thrice Upon a Time, on sending information ten minutes through time. Before you dismiss him becaue it's science fiction, he has impressive credentials in physics too. Anyways, he made the case that fluctuations would allow different outcomes. You send a message back saying to be careful because you just knocked over a vase. Hearing the message from ten minutes in the future, you look over at the coffee table and see the vase dangerously near the edge. You carefully reposition it in the center of the coffee table and never experience the accident. When you call ahead ten minutes, your future self also has never experienced the accident.

Chuck
2005-Feb-05, 01:55 AM
Suppose you receive a message from the future saying that tomorrow you get killed in a train crash, and you decide to take the day off so you are not on the train when history unfolds? :-?

A pickpocket steals your wallet and is still carrying it when he dies in the train crash. He's mistaken for you when his body is searched.

sidmel
2005-Feb-05, 03:13 AM
You've been duplicated by evil Sith cloners and your evil copy is the one that got run over. All's well, have a poptart.

Argos
2005-Feb-05, 12:15 PM
Farmerjumperdon, I like your point. Thatīs what I think about time travel.