new thread
You may think this question does not relate to men's long hair, so it actually should say :OFF TOPIC. But in fact it DOES relate to long hair! Ive read this forum for a year and I read many posts and Ive I've came to the conclusion that you are all very smart people. And I also came to the conclusion that we all have long hair/strive for long hair. So Im saying this is no coincidence. Long haired people are very smart. And smart people should answer smart questions... (SO shop Smart, shop S SMART... YOU GOT THAT!) so here it is...
Say you built I time machine, went back in time and killed your mother before she gave birth to you. (Just saying!) The thing is, if you went in time and killed your mother before you were born, you would never have been born to build the time machine and do the nasty deed, which means she could not have been killed. So what happen?!
Hey there :-)
Ive heard about this somewhere else I think... So basically, your suggestion cannot happen due to a "cosmic sensor" which would stop you from changing history.
Although if history was changed then nobody would know anyway!! So infact history could be changing all the time, and whilst right now we "know" that there was a second world war, if history changes right now, then you wont be able to read this as I would never have wrote it in the first place.... (If you asked the same question I might be saying something like well right now we know there was no second world war...)
Wow this stuff gets way to confusing and interesting..!!
Im going to Uni to study physics with astophysics so hopefully I will hear lots more about these theories, and can come back and update you with more info! :-)
I just grabbed this from www.bbc.co.uk:
"What about the paradoxes caused by time travel, like going back and killing your grandparents?
There are several problems that suggest that time travel is not possible. One of the arguments that is most frequently put forward is the so-called 'grandmother paradox': if you travel back to the past and kill your grandmother before your mother is born, you will not be born. Therefore, you could not have travelled back to the past to kill your grandmother, therefore you would be born!
Physicists have managed to come up with solutions to this. Some have proposed the Principle of Self-consistency: you can visit the past but are physically unable to change it. So, if you tried to shoot your grandmother, the gun would jam or you would be prevented in some other way from killing her. This is well illustrated in the film Bill & Ted’s Excellent Adventure. This seems to go against notion of free will but philosopher David Lewis made the point that free will does not allow you to do something logically impossible, such as instantaneously turning yourself into a tomato.
Another solution is suggested by Professor David Deutsch. He says that quantum mechanics tells us that parallel universes exist. So if you travelled back to past and killed your grandmother, you would simply end up being in a parallel universe where you had killed another version of your grandmother and were a time traveller.
One of the most famous arguments against time travel is that if time travel is possible, why haven’t we been visited by lots of time travellers from the future? Again, people have come up with ways round this objection: we may be inundated with time travellers and not be aware of it. Maybe that's what UFOs are. Perhaps civilisations don’t last long enough to develop the knowledge and technology required to build a time machine. And most convincing of all, general relativity says that you can only go back to the time a time machine was created. Since no one has built a time machine yet, no one can come back to this time."
Wow I like those theories. makes my brain buzz.
I'm convinced backwards time travel is impossible, anyway. There is one particularly convicing mathematical simulation that was done.
First, for a little background. Einstein conjectured, rightly, that the speed of light is a universal speed limit. Nothing can possibly exceed it. What Einstein didn't know was that it wasn't just a limit, it was the ONLY speed.
Did you know that all objects travel at the speed of light? It's true! You just have to remember that we are not three dimensional beings, but a least FOUR dimensional. Time is an oft-neglected and very, very important dimension of movement.
So, since I can obviously sit here at my computer and say that I'm clearly not moving at the speed of light, there has to be something wrong with that statement. Where is all the extra speed? In the time dimension, my friend. While I stand here, I'm moving at nearly the speed of light in the time dimension, thus aging and changing and generally moving forward in time.
Now, for example, I get up and walk to make myself some coffee. By doing this, I have increased my speed here in our three dimensions. If I add my 3D speed to my time speed, I would be going faster than the speed of light. But, since I can never exceed the speed of light, I slow down in the time dimension. Granted, the change is miniscule, but it does exist.
So, all I have to do to slow down time (for myself) is go really, really fast. Fast like, say, a Space Shuttle.
So here's where the wormhole comes in. A wormhole has two ends, it's basically the cosmic equivelant of a shortcut. I step in one end and walk out the other, right? Right. Now, someone came up with the idea of keeping one end of the wormhole here on earth, but taking the other end and moving it at extremely high velocity (I.E., setting it in orbit around the Earth). The end effect should be that the two ends of the wormhole exist in two slightly different times. Instead of walking through one end and appearing in another location, you should now be walking through one end and appearing in a completely different location AND time!
However, by the mathematics, the instant that the worm hold would have been usable as a time travel device, there was a massive explosion, far beyond any nuclear weapon.
It has become my pet theory that if you can think of a way to break the laws of physics, you'll end up with a gigantic explosion before you're allowed to cheat. : )
THREE WORDS... EX -CELL-ENT
Dude, that's awesome! I love physics, so much so that I'm planning on leaving school (6th form) and dropping all but two of my advanced level subjects and going to attend college instead where they've got an awesome physics department:)
I'm not 100% sure I'm going to do it though, there's only 2 girls there who are keeping me back, two who I incedently have a massive crush on.
Have you read The Elegent Universe, by Brian Greene?
I've read bits an pieces, yes. A very good work. I've gotten several people VERY confused with the NOVA special. : )
I used to have an idea that if going back in time was actually possible, hypothetically (just sorta appearing rather than slowing down time), surely the extra energy and matter of your arrival would upset the cosmic equilibrium of everything thus resulting in a massive expolsion. therefor, travelling back to when there was nothing... before the beggining, such an expolision within a miniscule area could infact have similar effects to the big bang.
slighty bigger odds than being your own mother i guess; in a way you would become your own God... proberbly just me talking crap but if any physists r on here, what would happen if extra matter or energy somehow popped into existence, with none leaving... would it just be a little crowded or would anything cool happen? am i making any sense at all??
You have too much time on your hands!
If you did go back and killed your mother, the future that you came from would cease to exist, but as you are no longer in that timeline, you would still exist in the past - you just could not return to the future...
...at least not the one you came from.
So if you returned to the time you came from, it would be a different future where you didn't exist - you'd have no ID, no birth certificate etc.
Either that or there would cease to be a future from the point where you killed your mother, as you would have changed time and therefore it would have to pick up from where it was changed. So you'd be stuck back in time when cigarettes were 20 cents a pack...
...all I need now is a time machine :)
wolfeyes
While in the middle of travelling back in time, theoretically you don't exist anymore as there is no one or no reference point to state you are there or confirm that you exist. Once you disapear from this world in this present, you cease to exist So it shouldn't be possible to kill your mother by goign back in time.
I wonder what being in a state of LIMBO looks like!?!......
Although it's been answered this way in another message, the parallel universe (Kabbalah's existence planes) is probably the best answer. The very fact of your being in the past alters it, therefore it is not your past. Killing your mother would prevent your being born in that plane of existence. The return would be interesting as well. *IF* you returned within that universe, you should cease to exist as your mother was killed by the you from the universe in which you did exist. If you returned to your own universe, then you would see no difference at all - and would probably conclude that it never happened.
Isaac Asimov covered this paradox in one of his books (I forget which one) except he used the example of his father.
However, if you were to consider chaos theory, then any change to the past would give a different future (your mere presence during a time when you did not exist). Ergo the paradox would come into effect before you found your father, or even got out of the "time machine".
Another thing that has to be considered with time travel into either the future or the past is the conservation of momentum. If you come into the past or future in a mechanical contraption, you are introducing mass into the system, without any momentum (assuming you're going for the classic, non-moving style time machine). Now visualize a billiard table with no friction and the pockets closed, with a bunch of moving balls. Without friction, the balls will continue to move forever, conserving their momentum. Open the pockets, and the momentum that the ball falling into the pocket (leaving the closed system) has will be lost from the system, and the remaining balls will be moving slower (conservation of momentum). If you keep the pockets closed, with the balls moving, and introduce a new ball (not moving), then the total momentum of the system will be spread across the entire mass of the system (once the new balls are hit by moving ones), therefore slowing down the system.
Now a single person in a time machine going into the future (introducing mass with no momentum) would not be that great, considering the massive amounts of momentum in the universe, but if you were to apply the limiting process to this phenomenon, the more mass you introduce into the system without momentem, the closer you come to actually stopping the entire system.
Did that make ANY sense?
That makes perfect sense, and at the risk of adding confusion, I must point out that you discuss only mechanical momentum (thereby mechanical engergy). The law of conservation of energy requires all forms of energy to be considered, as energy can transform between mechanical, electrical, thermal, chemical, nuclear, etc. Then there are also the effects of relativity, where mass and energy transform between one another. Therefore it is insufficient to state that a non-moving time machine is not inducing energy, without making assumptions as to the other energy that could be carried with it.
Then there's the case of the non-classic time machine, like the DeLorean in back to the future that will be travelling at 88 mph!
Good point, though I didn't want to completely swamp the non-physics minded readers out there!
Not only are my eyes crossed, but my hair's all tangled now, too.
How's that for getting a thread close to on-topic? ;-)
JE
This is something I have mulled over for at least 15 years. My conclusion is if you alter history even slightly you are asking for big trouble. If you affected history in a way that prevented your parents from being born or even meeting in the first place you would cease to exist. If you were to alter history in a way that did not affect your birth you may still return to your own time to a very different world. Here is an ezample. If you went back in time and started a pacifist movement in the USA in 1939 thus delaying the USA from entering WW2 you could return to a world ruled by nazi Germany. There was a Star Trek episode (The City On The Edge Of Forever) based on this. In a nutshell don't mess with the time line, if you do, you are asking for big trouble. Absalom
man, i don't want to look like a scientist, but u can't answer to this, 'cuz it just doesn't make any sense... despite to everythin' u've heard in all ur life, time machine cannot be build, fo' no reason... think 'bout it: time doesn't really exist, it's just something that we use to measure the course of our lifes. nature doesn't "record" things that happen, so that u can see'em again, i'm sorry... the only possibility would be if there existed some forms of soprannatural phenomena, in which case u could admit even time machines, but there wouldn't be any paradoxes anyway, 'cuz they would fix it all
Simple. You would forget about it because first you would not exist to think about it and eventually end up being born. But, since you don't really exist, then you could not possibly think about any time machine and killing your parent. Or you would end up like this guy....
http://www.zdrux.com/content.php?content.4
That is one of the things which means that time travel as you describe it is probably impossible.
Your going back in time would warp the universe so bad that you would fall into or create another universe, perhaps cloning our universe. You kill your mother and you go to jail. But in our universe your mother is alive and well and safe!
Time is linear so if it where possible to go back in time to kill your mother before she gave birth to u then doing so would alter the future time, future you at that instant would cease to exist upon killing yourself. However there is no sense in arguing this as its impossible, if time travel is possible then it is certainly only conceivable to travel forwards in time. If it where possible to travel back in time then we would be inundated at every point in our history with time travellers (since there is an countably infinite future ahead of us (end of universe is cut off point, provided we havent developed means to create our own universe or simply occupy another dimension/space)) then u would assume a countably infinite number of potential time travellers which should have visited us if possible). It is unlikely with such potentials also that they just havent been detected by us unless they are observing us from a space we are unable to see/reach).
Having just re-read your question, if you yourself built the time machine in your present and travelled back to kill your past then your time machine would cease to exist along with you. You would still be dead in your past tho, killed by your future self. Or maybe not, once again you cant really argue this, no one knows for sure... perhaps the universe would collapse in on inself since space and time are intertwined, you could unwittingly destroy everything. There is also a theory about meeting ur self in the past whereby you would cancel each other out I believe. There is no answer to this question. its sort of like "how long is a piece of rope?"
I still think it's impossible to go back in time without cloning the universe. The rate of time change can be slowed or increased or stopped, but the instant one goes back in history, the history is changed. You can not go back in time without changing history in the cloned universe. A person being present in their past would be able to see himself or herself in the past as a second person. What ever they do in that cloned universe would be as if they did it in the existing universe, but it wouldn't have any effect on our existing universe. So we would see that his mother is ok in our universe, but in his cloned universe he would be in jail for murder.
