# Wormholes and time travel



## Brian G Turner (Jun 9, 2003)

Okay, here's a link to a ercent article in Nature magazine about Wormholes - everyone's favourite* method of Time Travel. 

Making a wormhole just got easier...but it's no simple matter.

*meaning most scientifically plausably practical. 


So, to open up the discussion - Time Travel - possible or not?

If there is Time Travel then obviously none of us can go back in time and alter the past. Or could we? OR would the future then be part of the past and thus not negatable?

Is time even linear (past, present, future)?

Or wuold Time Travel actually never achieve more than travel into infinite possible universes where the past is like our own, only the future has not occurred - and if so, how would you know? 

Or is Time Travel itself not even remotely likely in any of the above scenarios?


Comments, if you will. ;D


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## nemesis (Jun 10, 2003)

If time travel were possible we would have met the future by now. The ability for humanity to invent time travel as fiction would have us believe is disproven by the conspicuous absence of time travellers.


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## X Q mano (Jun 11, 2003)

"Time-travelling" forward wouldn't be impossible I think, but back again? Hmmm...

I suppose, if you could make a ship travelling at far above light-speed or something, then time would be different for the occupants on that ship compared to earth. But back again, that would be a problem methinks...

And there are people who claim to be time-travellers... But more often than not we lock them up in rooms with padded walls...


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## Brian G Turner (Jun 12, 2003)

I like the idea that if time0travel were possible, it has alerady been accounted for by time, and hence the time travellers are here but are unable to change the past because the past always involved them and they were always unable to change whatever it was they wanted to change!


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## nightwalker (Jun 12, 2003)

It can't be done. If it could there would be no future to create time travel because there would always be someone changing the timeline. People could time travel to prevent the time machine being built and so create a parado,,,,I think.


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## X Q mano (Jun 13, 2003)

Anyone read Hitchhiker's guide to the galaxy series?

There you are presented with an interesting problem when it comes to time-travel... i think it's in the Restaurant at the end of the universe book...


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## Brian G Turner (Jun 13, 2003)

Saw the BBC TV series but remember little of it, other than as a kid I just didn't "get it".

Would you care to enlighten as to the restaurant at the end of the universe issue? Intrigued.


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## X Q mano (Jun 17, 2003)

I would have to grab my book at home... I'll see if I can do it tomorrow ok? It's really funny...


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## X Q mano (Jun 18, 2003)

Ok, here goes... This is a quote from the book "The Restaurant at the end of the Universe" by Douglas Adams. If I'm doing something illegal here, I apologize. It's a really great book and a great trilogy (of five books) and it is highly recommended.

ONe of the major problems encountered in time travel is not that of accidentally becoming your own father or mother. There is no problem involved in becoming your own father or mother that a broadminded and well adjusted family can't cope with. There is also no problem about changing the course of history - the course of history does not change because it all fits together like a jigsaw. All the important changes have happened before the things they were supposed to change and it all sorts itself out in the end.

The major problem is quite simply one of gramma, and the main work to consult in this matter is Dr Dan Streetmentioner's Time Traveller's Handbook of 1001 Tense Formations. It will tell you for instance how to describe something that was about to happen to you in the past before you avoided it by time-jumping two days in order to avoid it. The event will be described differently according to whether you are talking about it from the standpoint of your own natural time, from a time in the further future, or a time in the further past and is further complicated by the possibility of conducting conversations whilst you are actually travelling from one time to another with the intention of becoming your own mother or father.

Most readers get as far as the Future Semi-Conditionally Modified Subinverted Plagal Past Subjunctive Intentional before giving up: And in fact in later editions of the book all the pages beyond this point have been left blank to save on printing costs.


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## Brian G Turner (Jun 18, 2003)

That's actually pretty good.


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## dwndrgn (Jun 19, 2003)

The Guide is hilarious!  I recommend it to anyone who just needs a chuckle to make a bad day better.  ;D

As for time travel...well, I'd like to believe it but it just doesn't fit into my own personal form of logic.  Just the fact that time itself is an idea, not a fixed thing sort of makes the logistics a little weird.  My brain is wiggling just trying to think about it.  

I find the idea of *place* travel much more plausible - that there are parallel universes/realities that could be *jumped* to, as depicted often in fantasy novels.  I couldn't really tell you why this seems more plausible  ???  Maybe I am just more fascinated by it so want to believe it.


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## Brian G Turner (Jun 25, 2003)

Would anybody actually _want_ to go back in time and intentionally change the past?


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## X Q mano (Jul 1, 2003)

It would be tempting sometimes... But I have made up my mind to never regret anything... So I would try not to change anything either...


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## Brian G Turner (Jul 1, 2003)

Ah - but what about regretting what happens to _other_ people, though? For example, I figure a lot of people would want to prevent the implementation of "the Final Solution" the Nazis. However, wouldn't stopping that have an inadvert negative impact? In the realm of genetics that we currently explore, the whole issue of Eugenics has been thoroughly destroyed precisely because of the Nazis. However, before them it was an entirely respectable field. Without Hitler, we could be stumbling into a whole different Eugenics nightmare right now - and with far, far, more powerful tools.


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## Arch (Jul 3, 2003)

I would go back in time, collect some items I know are rare in the present day, and then bury them. Then I would return to the future to where I buried those things and then unbury them! Hence I become rich and the world and is enriched by my new discovery!


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## littlemissattitude (Aug 11, 2003)

May I recommend Kage Baker's series of novels about an entity called the Company, which will, in a couple of hundred years or so, invent both time travel and immortality?  She has some interesting takes on how time travel could work and how to avoid paradoxes.  The books are: _In the Garden of Iden_, _Sky Coyote_, _Mendoza in Hollywood_, and _The Graveyard Game_.  There is also a collection of loosely related short stories, the title of which I cannot recall offhand.

Oh, and also David Gerrold's _The Man Who Folded Himself_.  This is a quick read from the man who gave us Tribbles, which postulates that wherever a paradox might logically occur during time travel (as, when we meet ourselves), another time thread or alternate universe opens up.  It has been a long time since I read this one, but as I recall it was a fairly entertaining book.

For another take on time travel, one which is in a very real way much more pessimistic about its effect on the world, try _Pastwatch: The Redemption of Christopher Columbus_, by Orson Scott Card.

As far as the possible reality or possibility of time travel goes: I don't the know the physics involved, so I can't comment on it on that level.

I just know that I love time travel stories, and some part of me hopes that it is possible.  I think it is the historian in me, who would love to be able to witness past events to see what really happened, as opposed to the interpretations of those events that have come down to us.

By the way, is there anyone here old enough to remember the old television series, "The Time Tunnel"?  It was quite cartoonish, but lots of fun at a time when we really didn't have much science fiction on television.


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## Brian G Turner (Aug 13, 2003)

Ah - now, we're really into multiverse theory there! Used to be a favourite of mine (now I simply don't think about it - or am simply not sure what to think).

Anyway, here is the website of David Deutsche, who is the effective progenitor of multiverse theory:


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## dwndrgn (Aug 13, 2003)

I loved the Kage Baker books.  Wish there were more.  I love time travel stories as well - but usually only if they go backwards through time instead of forward.

Very nicely done - lots of thinking involved, good character develpment and wonderful historical scenes.


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## Brian G Turner (Aug 23, 2003)

Just found something else about Wormholes from the Ne Scientist website:

*Quantum wormholes could carry people*

All around us are tiny doors that lead to the rest of the Universe. Predicted by Einstein's equations, these quantum wormholes offer a faster-than-light short cut to the rest of the cosmos - at least in principle. Now physicists believe they could open these doors wide enough to allow someone to travel through.

Quantum wormholes are thought to be much smaller than even protons and electrons, and until now no one has modelled what happens when something passes through one. So Sean Hayward at Ewha Womans University in Korea and Hisa-aki Shinkai at the Riken Institute of Physical and Chemical Research in Japan decided to do the sums.

They have found that any matter travelling through adds positive energy to the wormhole. That unexpectedly collapses it into a black hole, a supermassive region with a gravitational pull so strong not even light can escape.

But there's a way to stop any would-be traveller being crushed into oblivion. And it lies with a strange energy field nicknamed "ghost radiation". Predicted by quantum theory, ghost radiation is a negative energy field that dampens normal positive energy. Similar effects have been shown experimentally to exist. 

*Delicate balance*

Ghost radiation could therefore be used to offset the positive energy of the travelling matter, the researchers have found. Add just the right amount and it should be possible to prevent the wormhole collapsing - a lot more and the wormhole could be widened just enough for someone to pass through.

It would be a delicate operation, however. Add too much negative energy, the scientists discovered, and the wormhole will briefly explode into a new universe that expands at the speed of light, much as astrophysicists say ours did immediately after the big bang.

For now, such space travel remains in the realm of thought experiments. The CERN Large Hadron Collider in Switzerland is expected to generate one mini-black hole per second, a potential source of wormholes through which physicists could try to send quantum-sized particles. 

But sending a person would be another thing. To keep the wormhole open wide enough would take a negative field equivalent to the energy that would be liberated by converting the mass of Jupiter.


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## GnomeoftheWest (Aug 23, 2003)

I would go back in time and become an oracle.

(and write the Beatles' "Yesterday" myself)


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## dwndrgn (Sep 4, 2003)

Wow, I didn't realize they had gotten that far working with wormholes.  Maybe our kids' kids will be able to travel accross space like that!


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## BlueSkelton (Jun 18, 2004)

According to Einstein (the leading expert as of right now id say) Time travel is not possible. The interesting thing Einstein said was possible was that it might be possible 
to look back or forward in time.
I have yet to see any definitive answers other than what einstein wrote and if 
their are any studies out there that are published i would love to hear bout them


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## polymorphikos (Jun 18, 2004)

I think the thing to remember with timetravel is that we are not living in the present, we are living in someone else's future. That is to say that no-one, for example, has ever destroyed Sydney with an atomic device. Therefor, in our universe atleast, no-one could ever go back and destroy Sydney with an atomic device, because we'd know about it. I'm of the mind that if there are timetravellers, then they're inconspicuous or in the deep past, and all the changes and paradoxes and such that we talk about have happened. Timetravellers probably have had a direct influence on the past and present, but it all fits into our perception of the course of histriy. Some people will say that this is a belief in predetermined destinies, but it's not. It's just realising that, logically, we exist and our past exists and so, relative to anyone from our future or present going back in time, they will not be able to change anything because it already happened and they know about it. 

I probably misexplained myself, but that's my opinion.


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## Jayaprakash Satyamurthy (Jun 18, 2004)

Time travel happens. We are contantly travelling into the future at the speed of one second per second. Einstein evnisaged travel into the future at lightspeed. Kip Thorne has shown how a 'tame wormhole' could be used as a secure portal permitting two-way time travel between two distinct points in space and time. 


Time travel back to our past, however, is something that even now seems to have no theoretical basis. A good overview of current theories and speculation can be found in Paul Davies' How To Build A Time Machine.


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## ste-makina (Nov 11, 2005)

any one intrested in time travel should look up 9dimensional theory on the internet or maybe they should watch the bill and ted movies.. ha if time travell is ever goin to be possible they are already here maybe they are being kept locked up maybe they are hiding but in the end how can they keep it from people some one must find out eventually but they would probably be locked up too  if you ever saw the movie k-pax thats how it would be for a time traveller also nobody would believ them so how are we supposed to know if they are telling the truth if the truth is impossible. and if people can time travel in the future they can do it now because the time travellers would build a time machine in the now ..ok cya


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## ste-makina (Nov 11, 2005)

thinking about time travell fees weird


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## Eradius Lore (Nov 11, 2005)

due to the theory that time travel creates parallel universes for every decision that was ever made, once you have passed the event horizon and travelled back through time a new time paradox is created, subsequently forming a new universe, once there a time machine would not send you back to your plane of existence, for that you would need a controlled quantum singularity generator. This in theory would allow you to return to your own dimension.


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## ras'matroi (Nov 12, 2005)

The only theory, I know of, that could be called timetravel and is known by now is based on the theory of relativity.

Time is relative and goes slower if you move. There are experiments with particle accerleraters which confirmed that. It is possible to prove it theoretical, too.

=> it might be possible travel foreward in time by moving almost at the speed of light. The person moving inside the moving container would experience time. But it would run slower than outside.

The problem is that it would be impossible to travel back.


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## Quokka (Nov 12, 2005)

gravity affects relative time as does speed, there are also quite a few theories that state that, relative time tavel backwards must be possible... of course those same mathimatics indicate that *we* are almost definately not real or atleast not the starting point of life: aka gregory benford's_ cosm. _We simply know to little, today


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## Dave25 (Nov 12, 2005)

I am unsure as to whether time travel is possible but potentially at least I like to think it is. Purely speculating based on our current understanding that time is just a dimension, we can travel backwards and forwards in the x,y,z directions (spatial dimensions) then why not in time as well? Perhaps time is different to the spatial dimensions but so far time seems to interact with them in things like mathematical or scientific equations so perhaps not. I suppose it all depends on exactly what would be classed as time travel

My views on the multiverse have changed a little after recently watched some programs on creation of the universe etc... In that I never gave this idea any credability but now I think there is maybe just maybe a chance of these mutliverses existing. However, if they do I have no hope that it would be possible to travel between the multiverses.


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## chrispenycate (Nov 14, 2005)

And there's me complaining about the use of "multiverse" to explain that the universe (all the matter and space that exists, by definition) has a few more dimensions and a bit more matter than previously considered. here I get landed with "multiverses" Arrg!

A straight forward four dimentional universe does not disallow time travel, but it is static: everything that will be done, has been done or is being done is fixed. The ultimate in predestination, no problem of paradoxes and pretty boring for stories. It would allow filming the crusades of solving murder mysteries bu not much else.

The "time scan" facility which would allow information (but not matter or energy- that'd contradict conservation laws) to come forward along the entropy arrow- not much more use. Running it backwards is disturbing- if the moment you get your time machine running there's a note in it from yourself telling you how to build it better, which horse to back and tomorrows weather, that's saved us a lot of trial and error.

Add a dimension or two and  you can travel into the past. Unfortunately you can never come home again, as your appearance has either changed the universe into one in which several kilos of mass suddenly appeared fom nowhere, or splits off an alternate, running parallel, which steadily diverges from previous history. Somehow takes some of the point out of it.

Of course, we hit some other slight problems- if we travel from the surface of a planet, when we arrive, the planet's not there. Or, if by some freak of orbital dynamics it happens to be, it's not moving at the same speed. It would be much wiser doing it in a spacecraft, and finding the planet later (probably what all those UFOs are) H.G.Wells put his machine in fast forward rather than hop mode, so its weight and friction stopped it from detaching itself from the surface of the planet, probably very wise, but he was lucky that the surface of the planet stayed at the same level- rare over such periods- so embarassing to find oneself buried under five meters of rock, or twenty meters above the surface of the sea.

Philosophers tell us we can never go home, and if time travel were to be invented I'm surethere would be students willing tu come back to a very slightly changed reality in exchange for the knowledge gained, paying enormous attention to make minimal changes so they can still operate their word processors when they got back. And, sooner or later there'd be someone who'd decide the world could only be better if Hitler were assasinated in 1936, (and WW2 would start eight years later and everyone would have atomic weapons) and the a time traveller from that sequence would come back and change everything, and history would go on a wild roller coaster ride until, on one cycle, no-one invents the time machine, ever, and that one's stable, so here we are in it and I'm travelling into the future at sixty seconds per minute, thank you very much.


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## dreamwalker (Nov 15, 2005)

TIME TRAVELING AT 60 WORKS PER MINUTE WILL BE OUT LIMIT

famous quote, not sure who it was by, but I don't think it would be wise to travel backwards in time for all the reasons just mentioned. I watched the simpsons halloween special, the one with the time traveling toaster.It was pretty stupid, but fun none the less and reminded me about the key issuse. 
*Why would you want to change the past? *Why would you want to forget or negate all the things that our past has taught us? Even if bliss would be possible, would you ever be happy with bliss for ever?


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## chrispenycate (Nov 16, 2005)

dreamwalker said:
			
		

> TIME TRAVELING AT 60 WORKS PER MINUTE WILL BE OUT LIMIT
> 
> famous quote, not sure who it was by, but I don't think it would be wise to travel backwards in time for all the reasons just mentioned. I watched the simpsons halloween special, the one with the time traveling toaster.It was pretty stupid, but fun none the less and reminded me about the key issuse.
> *Why would you want to change the past? *Why would you want to forget or negate all the things that our past has taught us? Even if bliss would be possible, would you ever be happy with bliss for ever?


Perhaps ¿Baxter ,wasn't it? Timescape? message from the future saying "when you are going to have started this power station it will have produced black holes which are going to be eating the planet that I'm standing on and you're going to would and here's the mathematics to prove it so perhaps it would be a good idea not to particularly since you're going to be me if you do" or Varley's "air raid" where the travellers came from a time so desperate that they consider the dissolution of the universe preferable- everybody has his break point, I merely don't know where mine is.


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## Dean (Jan 12, 2006)

firstly, I think its possible, I think backwards to memories of loved ones all the time, but to actually go there is conceptual. If you did you would almost certainly alter something that would destroy the foundation that made your own time line viable, and so you would go out with a quick Ker-pop. What if time does not exist at all in the first place? you measure the minutes by the clock on the wall, but nothing evidentual eludes to the existance of time that can be travelled through like some cosmic stew. I think it comes down to atomic structure, we see time because matter decays. new structures become old, still nothing visible as "time" And arnt we time travellers ourselves anyway? At least forward, whatever direction that is in time.
As to whether I would want to change the past? Yes, she did not deserve to be pre-empted by a psychotic gunman, and I feel like it should have been me that passed, and as far as destiny? Nope. I just cant beleive I am the completely miraculous invention of a cookie cutter. So I have the power to choose my fate, as many times a day as I like and that is power, the power to choose my own destiny.


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## Sandro (Sep 2, 2006)

Hi there,

I stumbled accross this forum and had to join as I found your writings very interesting. As a professor I have to ask you to ask yourself if you are a fantasist or a realist? - And then to further ponder space, time and quantum physics. (It is all about susceptibility and whether your brain can actually comprehend what you are about to learn - Einstein was good at this).

I can tell you that time travel is only possible from a theoretical point of view and always will be. You cannot go back in time or forward into the future.

Time is what is real to our world and to its people as a measurement. The fact that atomic clocks which fly around the world on planes and have a different reading to ones set at precisely the exact time, but which were left on solid ground should prompt you to think about which clock is really right!

I believe that as you have expressed an interest in the subject, then another area which is sure to fascinate you would be:

Particle accelleration and the artificial creation of black holes (already done in Geneva by scientists!)

Keep up the good work chaps!

I thank you

Prof. Alessandro J Rabar
(Manchester)


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## Sandro (Sep 2, 2006)

Hi,

Do you really think that time travel is possible? Firstly, forget the TV programs of the 80's and stop trying to hold on to the notion that you could have stopped your old dog from dying or have prevented splitting up from your partner back in 1996!

This should really get you going...

Black holes have a gravity so strong they can suck in light itself.

Then, If you were to enter a black hole - which should throw you out at some random, undefined place somewhere else - what would be the opposite of a black hole?

A white hole which spat you out at speeds which would destroy you just as the black hole did?!?

Space is no different than my toaster - the front is the opposite to the back!

If I shone a laser into a black hole would I indeed blind some poor alien in another place in another time?

Q) What is behind a black hole? The answer...

A) The back of a black hole.

I thank you.

Prof. Alessandro J Rabar
Manchester (UK)


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## steve12553 (Sep 2, 2006)

If history teaches us anything, isn't it that we always have more to learn and the more we know, the more we understand that we don't? That, Professor is the beauty of Science Fiction and Fantasy. Although we do appreceate the hard facts even though for the purpose of this forum, we'll assume they are a little soft. 

By the way, Greetings and Felicitations.


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## carrie221 (Sep 2, 2006)

Umm... I believe that time travel is possible it is just that as far as the general public knows we don't have it yet but anything is possible and I do mean anything. All history and science has taught us is that it can and probably will be rewritten many times in the future and as was pointed out above the more that we know and discover the more we will realize that we don't know anything.


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## The DeadMan (Sep 22, 2006)

I think that if time travel were possible it would only be into the past, and even then you would only be able to observe events but not interfere with them. If this were true then future generations could be observing our time period and even futher back and we would be completely unaware!


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## Dave (Sep 23, 2006)

I have to disagree. I don't believe time travel to the past will ever be possible.

My reasoning is just logical, not based on the practicality of it. If it ever were to become possible, then time-tourists would travel back in time to observe past events. Just as certain geographical places become tourist traps, certain time periods and events would become time-tourist traps. Now, think of an event in the past that you would like to visit yourself. Does history record a huge number of spectators who suddenly turned up just before it happened?


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## The DeadMan (Sep 23, 2006)

Dave said:
			
		

> I have to disagree. I don't believe time travel to the past will ever be possible.
> 
> My reasoning is just logical, not based on the practicality of it. If it ever were to become possible, then time-tourists would travel back in time to observe past events. Just as certain geographical places become tourist traps, certain time periods and events would become time-tourist traps. Now, think of an event in the past that you would like to visit yourself. Does history record a huge number of spectators who suddenly turned up just before it happened?


Many of history's greatest events and greatest disasters were witnessed by large numbers of people. The World Trade Center, The Space Shuttle Challenger explosion, the Atomic bombing of Japan in WWII. Whose to say that some of those people who witnessed those events might or might not have been time travelers. Of course some events one might like to witness are known to have only one or two people present. If as my idea states one could not interfere with the past then one would not be able to appear at those events.


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## Leandra (Sep 23, 2006)

It's a really interesting issue, to say the least. I believe time travel is possible, but that you can't change the future, because it already counts with you changing it. An example would be the end of the third Harry Potter book (the main characters should have known that they wouldn't be seen because they hadn't seen their future selves) or Philip K. Dick's short story _The Skull.

_I hope it makes sense - anyway, the theory was already mentioned here several times. 

Personally, I would only go to the past to observe, not to change anything. I also have a point about not regretting anything that has ever happened to me and going on... Which leads me to:



			
				brian said:
			
		

> Ah - but what about regretting what happens to _other_ people, though? For example, I figure a lot of people would want to prevent the implementation of "the Final Solution" the Nazis. However, wouldn't stopping that have an inadvert negative impact? In the realm of genetics that we currently explore, the whole issue of Eugenics has been thoroughly destroyed precisely because of the Nazis. However, before them it was an entirely respectable field. Without Hitler, we could be stumbling into a whole different Eugenics nightmare right now - and with far, far, more powerful tools.


My theory is that perhaps, before, the WWII and all was much worse (hard to imagine, sure, but anyway). For example there was a different leader than Hitler, who made an even narrower choice of who to let live, wiping out ninety percent of the world in the end. Then a time-traveler zoomed back, got rid of this person and replaced him with Hitler, who was maybe weaker and had a bigger chance of losing. The Final Solution stayed, but there was no negative impact, like Brian wrote. Thus the situation turned out as we know it today and we never suspected anything.

There's a slight catch, though. When we would get to the future, there would have to be a mention of the time-traveller and some details. Otherwise we wouldn't know that we're supposed to send someone out... Darn, I'm getting too caught up in this! I hope I managed to get the idea across. The best way would be to read _The End of Eternity_ by Isaac Asimov. That's where I got the theory from, and Eternity itself (a name for an organization, not the real thing) is a very cool concept as well.



			
				ste-makina said:
			
		

> any one intrested in time travel should look up 9dimensional theory on the internet or maybe they should watch the bill and ted movies.


Yay! Bill and Ted  I've only seen the first movie, but the _best_ part was when they were walking down the street (in their time), and one of them bent behind the billboard and took out the keys.



			
				chrispenycate said:
			
		

> A straight forward four dimentional universe does not disallow time travel, but it is static: everything that will be done, has been done or is being done is fixed. The ultimate in predestination, no problem of paradoxes and pretty boring for stories. It would allow filming the crusades of solving murder mysteries bu not much else.


It looks like chrispenycate had voiced my theory in a far less complicated manner! So, basically, this is what I had meant 



			
				chrispenycate said:
			
		

> The "time scan" facility which would allow information (but not matter or energy- that'd contradict conservation laws) to come forward along the entropy arrow- not much more use. Running it backwards is disturbing- if the moment you get your time machine running there's a note in it from yourself telling you how to build it better, which horse to back and tomorrows weather, that's saved us a lot of trial and error.


I've always wanted to try the horse-betting one. I read a story about a man who could communicate with himself as he would be in 48 hours. He became a millionaire by working the stock market.



			
				chrispenycate said:
			
		

> Of course, we hit some other slight problems- if we travel from the surface of a planet, when we arrive, the planet's not there. Or, if by some freak of orbital dynamics it happens to be, it's not moving at the same speed. It would be much wiser doing it in a spacecraft, and finding the planet later (probably what all those UFOs are) H.G.Wells put his machine in fast forward rather than hop mode, so its weight and friction stopped it from detaching itself from the surface of the planet, probably very wise, but he was lucky that the surface of the planet stayed at the same level- rare over such periods- so embarassing to find oneself buried under five meters of rock, or twenty meters above the surface of the sea.


I think time machines would have that figured out - either they would change place with the rock (so they'd end up in a time machine-shaped hole in the middle of the mountain... but at least they won't be squashed) and then bore out of it like a mole. Or the travellers would figure out what the place will look like in the future - like jumping through hyperspace. You also have to make sure you won't end up in the middle of a sun.



			
				Sandro said:
			
		

> As a professor I have to ask you to ask yourself if you are a fantasist or a realist? - And then to further ponder space, time and quantum physics. (It is all about susceptibility and whether your brain can actually comprehend what you are about to learn - Einstein was good at this).
> 
> I can tell you that time travel is only possible from a theoretical point of view and always will be. You cannot go back in time or forward into the future.


I'd be the first to admit I know _nothing_ about physics, the theory of relativity, etc. But isn't it a bit early to make such a judgement? From today's point of view, and quite well many future years' point as well, it is impossible. However, maybe someone will make a grand breakthrough sometime in the future and will get the hand of time-travelling. *shrug* 

Anyway, at least there's still hope (and A. C. Clarke's first law )



			
				The DeadMan said:
			
		

> Many of history's greatest events and greatest disasters were witnessed by large numbers of people. The World Trade Center, The Space Shuttle Challenger explosion, the Atomic bombing of Japan in WWII. Whose to say that some of those people who witnessed those events might or might not have been time travelers. Of course some events one might like to witness are known to have only one or two people present. If as my idea states one could not interfere with the past then one would not be able to appear at those events.


I think that too. Nicely stated *grin*.

I apologize for the lengthy reply - the subject is just so intriguing that I had to add my two cents. And it was great reading through ll of your responses


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## j d worthington (Sep 23, 2006)

No need to apologize for lengthy responses ... you should see some of my older (and, who knows, future?) posts.... oh, my!

While I tend to agree that time travel will only ever be theoretically possible, I also agree that there may yet be an undiscovered science or aspect of the universe that may stand that on its head; so I'll say that I think the probability is nearly -- but not entirely -- nil.


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## steve12553 (Sep 23, 2006)

I'm kinda bothered by the word "believe" in this thread. Time travel either is, isn't, will be, or won't be possible. It doesn't matter what I believe or what you believe. You can believe that you can breathe underwater and you'll still drown. We can theorize or we can subscribe to someone else's theory. I'll hold an open mind till I see proof or I die.(Or become senile) Save the word believe for religion, morality (I believe in the sactity of life), or if proof is offered (When he brought back next Thursday's paper, I still didn't believe it was real.)

OK, I'm through complaining. My back still hurts, but I've had my say.


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## Dave (Sep 23, 2006)

steve12553 said:
			
		

> I'm kinda bothered by the word "believe" in this thread. Time travel either is, isn't, will be, or won't be possible. It doesn't matter what I believe or what you believe. You can believe that you can breathe underwater and you'll still drown.


I can believe that one day, some time in the future, science will allow me to grow gills, or invent oxy-gum that I can chew and breath underwater, but what I meant was, I think science is unlikely to invent a time travel machine that can travel to the past for the reason I gave. And that was a philosophical reason rather than a practical one.

On the other hand, if backwards time travelers cannot have any influence, can only observe, and may not be seen, that would defeat my argument. Maybe this is even an explanation for the appearance of ghosts.


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## steve12553 (Sep 23, 2006)

Dave said:
			
		

> I can believe that one day, some time in the future, science will allow me to grow gills, or invent oxy-gum that I can chew and breath underwater, but what I meant was, I think science is unlikely to invent a time travel machine that can travel to the past for the reason I gave. And that was a philosophical reason rather than a practical one.


 
Having faith in Science is basically having faith in the ability of the human race to develope something in the future. That's different than believing that a fact is true. A fact is either true or not true, I doesn't matter what you believe. Whether the future is certain or changable is philosophical (at least at this point in time) and subject to belief. Belief in Science and the uncertainty of the future is what drives these forums and keeps all of us thinking.


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## Dave (Sep 24, 2006)

steve12553 said:
			
		

> Having faith in Science is basically having faith in the ability of the human race to develope something in the future. That's different than believing that a fact is true. A fact is either true or not true, I doesn't matter what you believe.


I never disputed that, but I would add that Luminiferous aether was once believed to be true, and now it is not true. These working hypotheses about Wormholes and Time Travel are still being tested. We probably have a few million years left on this planet to investigate. It may be possible to find a Wormhole or a Cosmic String that can be travelled through (and back again) without the traveller being reduced to Neutronium, but until one is found it is purely speculation and conjecture. 





			
				steve12553 said:
			
		

> Belief in Science and the uncertainty of the future is what drives these forums and keeps all of us thinking.


And long may it do so! Now I return you to the speculation and conjecture!


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## Specfiction (Sep 26, 2006)

There are those things that are possible and those things that are not. The problem is that we don't know what they are.

Although Matt (Vissor) came up with a neat way to "open" the throat of two bacl-to-back black holes years ago, we still have the following issues:

1) We've never seen a black hole, we've only seen them inferred by things like gravitational lensing, etc...

2) We've never seen a wormhole even inferred--they may not exist.

3) We've never seen exotic matter in any form, only the inference of exotic matter effects between Casmir plates, and, of course the new interest in the cosmological constant. But all of this is Speculative (fiction?).

4) Hawking believes that feedback effects in time-loops prohibit any interaction with the past (as a boundary condition).

5) Causality, if it is a real principle, would be violated by time travel into the past.

But if we can get past all that, not to mention engineering on a scale tha people can't even imagine, then yes, time travel would be a blast...


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## Harpo (Sep 26, 2006)

"Time-travel will never be invented because we can't see any time-travellers" goes the argument against.  

But what if, instead of a time-machine being a machine which travels through time, it is a machine in which people can travel through time (within the operational lifespan of the machine).  

This way, time-travellers will be able to travel into the past as far back as the day the first working time machine gets switched on.

Suppose that day is December 21st 2012 - when the Mayan Calendar says our concept of time will change.

I'm looking forward to it.


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## carrie221 (Sep 26, 2006)

Okay if we have the technology to build time machines maybe we would also have the technology to build invisability cloaks (or we could just borrow some from the wizarding world) then there could be poeple watching all these events without us seeing them.


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## steve12553 (Sep 27, 2006)

carrie221 said:
			
		

> Okay if we have the technology to build time machines maybe we would also have the technology to build invisability cloaks (or we could just borrow some from the wizarding world) then there could be poeple watching all these events without us seeing them.


 
If I were to critique a story that used borrowing from the wizarding world out of the blue like that, I'd call it a cop out. But I not, so I won't.


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## carrie221 (Sep 27, 2006)

steve12553 said:
			
		

> If I were to critique a story that used borrowing from the wizarding world out of the blue like that, I'd call it a cop out. But I not, so I won't.


 
Oh but I am not talking about a story... I am talking about reality  

If Harry's cloak is an antique then the technology has to have been around for awhile so they could be watching all of us right now (Have to go now prof is leaving story land)


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## Harpo (Sep 27, 2006)

another thought: suppose when JFK was shot there was a time-travelling tourist (for example) standing on the grassy knoll?
and wasn't there an unidentified mystery ship reported in the area when the Titanic sank?


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## steve12553 (Sep 27, 2006)

Harpo said:
			
		

> another thought: suppose when JFK was shot there was a time-travelling tourist (for example) standing on the grassy knoll?
> and wasn't there an unidentified mystery ship reported in the area when the Titanic sank?


 
And maybe a few passenger in steerage who somehow managed to escape intime.


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## carrie221 (Sep 27, 2006)

steve12553 said:
			
		

> And maybe a few passenger in steerage who somehow managed to escape intime.


 
  That would be soooooo cool could you imagine getting to explore the past like that... wow


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## Harpo (Sep 27, 2006)

crowds of time-tourists pretending to be the ones who didn't survive historical calamities? The Lost Tribes of Israel? The Mary Celeste?


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## Memnoch (Sep 27, 2006)

nemesis said:
			
		

> If time travel were possible we would have met the future by now. The ability for humanity to invent time travel as fiction would have us believe is disproven by the conspicuous absence of time travellers.


 
We wouldn't be aware of time travel due to there ability to adjust history, if we met a traveler of time and space and we realised his identity then surely he would go back in time n stop him meeting us!! If ya get me? If history was altered also we wouldn't be aware due to everything adjusting from that point and us in the present would be oblivious!!! 

Bill Gates is a Time Traveler I'm convinced, or the anti christ, or met a djinn as youngster and was granted a wish (obviously didn't get more than one as he would have improved his looks lol) !! (Sorry for the tangent guys)


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## Specfiction (Sep 27, 2006)

> Okay if we have the technology to build time machines maybe we would also have the technology to build invisability cloaks (or we could just borrow some from the wizarding world) then there could be poeple watching all these events without us seeing them.



Think about what is real, from your own (objective) experience. Think of the real lives of people in the "dark ages" and the lack of measurable progress they made by confusing superstition with reality. The world was flat, doctors bled patients to cure them, no body washed their hands before patients were treated, ships were little better than corks, navigation was a matter of luck.

Things like time machines are a different order of intellectual exercise from anything that we can imagine today (in a sober way). And the chances that such a thing is possible, even by intellects that are as far above people as we are above ants, is very small.


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## Harpo (Sep 27, 2006)

in a future earth where time-travel is as common as car travel for us, they all know that we in 2006 had no way of knowing how to do it.
They also know the date that we learn how, and when that date comes most of us will be very very confused


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## Specfiction (Sep 27, 2006)

Ponder this. I think we all become a little taken away with modern accomplishments, but in truth, they are very modest. Although we've been able to do some neat things with electronics, TV, computers, the Internet; we have not really achieved any of the hard things. 

Energy production: like the Bronze Age before us, we mostly burn oil and coal. The nuclear energy we have is scarcely better than some sources naturally occurring, and our best yields are scarcely 3% and very dirty—to the point where we almost can’t use it. We're having a very hard time getting back to the moon and our rockets are better versions of what the Chinese created thousands of years ago. 

Time travel, which is probably not possible, no matter how advanced a civilization is, would probably require energy on a planetary scale. If it were possible, and it probably isn't, it would not be a casual matter.


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## j d worthington (Sep 28, 2006)

I'm afraid I'd go even further; I think, from my understanding of the actual theory surrounding the concept, based on genuine astrophysics as well as as particle physics, etc., the energy required, _were such a thing possible_, would quite literally be more than our sun would produce in its entire lifetime, and that for only a very modest trip of a few moments. As reality, unless we invent an entirely new physics _from the ground up_ (not piddling changes such as Einstein or Planck have introduced -- and they are piddling, compared to what I'm talking about), it simply is not realistically possible.

As speculation for fiction, however, I'm all for it (I love time travel stories, and I love paradoxes, as long as they're intelligently done). However, a flagrant violation of physics as we understand it tends to leech life out of most stories, and should be avoided if at all possible. Otherwise one ends up with a simple wish-fulfillment fantasy, not a mature piece of fiction that stands up under rereading, or any serious thought.


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## Specfiction (Sep 28, 2006)

I agree. I was trying to be optimistic about the reality of the venture.


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## steve12553 (Sep 28, 2006)

One thing to consider. Within the span of our recorded history, most people believed the Sun circled the Earth. Our concept of the Sciences have changed by leaps and bounds since then. I am willing to grant our ability to misunderstand the universe to that degree and through changes in view and discoveries of better measuring equipment, that some day we may have such a different view of things as to make the concept of time travel possible. Other eras of humankind presumed they had a pretty good grasp on the universe. As I grow older and continue to learn, what I learn is how much I have left to learn. I suspect humanity as a whole should at least try to look at things the same way. I don't think we've reached "godhood" just yet.


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## Briareus Delta (Sep 28, 2006)

Quantum Physics Rule 1 (or could be Rule 363 for all I know about the subject) - *Anything* is possible


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## Specfiction (Sep 28, 2006)

> One thing to consider. Within the span of our recorded history, most people believed the Sun circled the Earth.



At this time, science, as we know it, did not exist. Belief is not science. Science requires proof and critical peer review, and reproducibility. That's why it took so long just to get to this very modest state of development.




> Quantum Physics Rule 1 (or could be Rule 363 for all I know about the subject) - Anything is possible…



According to QM there are a set of conservation laws that dictate what is possible. For example, processes that don't conserve energy and momentum are NOT possible. There are many other conservation laws as well as causality, which is respected by QM. Time Travel, on a macroscopic scale, violates causality. 

The correct statement is: "Any state that does not violate physical laws is possible."


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## SteveR (Sep 28, 2006)

Cool thread. 

For me it's actually a non-argument. Time is....well exactly, what is it?  It's a mental perception of something that does not actually exist. So if it does not exist, how can you travel through/in it?

I find it interesting that humans have a need the concept of time. Things are. We are. There is no past, no present just now. At the risk of sounding like I'm quoting from Babylon 5, the moments are all that we have.

Just like numbers - concepts our brains have developed to help us to 'understand'. But they are not real, just like time isn't real.

Ok, said my piece. 

Oh, and nobody is alllowed to ask "But, what is real anyway?" 

Steve


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## Kbanfield (Sep 29, 2006)

Hey...here are my 2 cents...

Though we understand time as a mental perception does not mean we cannot travel through it. I think we have a long way to go to really developing an understanding of how time actually works which I think should leave the possibility of time travel still on the table. 

We can reach a better understanding through our desire to do something. I was watchin this preview of a new movie called The Fountain and it was essentially about a guy going through time to find a cure to save his lady...I think its stuff like this that will push us to come up with the necessary methods to time travel.

What do u think?

The funny thing is...in 100 years...someone will travel back to read this conversation...


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## j d worthington (Sep 29, 2006)

It's an interesting concept, yes; and as I said, I very much enjoy time travel stories. But the problem here is that, as opposed to the differences in viewpoint referred to earlier, when science as such was extremely primitive and understanding of the laws of nature was not only sparse but uncoordinated and often impossible to test, time travel completely violates several aspects of physics that, by all evidence, are constants; they are the very basis of how the universe works. So while I won't completely rule out the possibility of an entirely new science -- and, as I said before, this means _an entirely new science, with everything we've learned so far scrapped and starting from zero_ -- the probability is indeed nil; and that is what science is: probabilities based on empirical, testable evidence. True, in order to be science it must be "falsifiable"; but there is absolutely no evidence indicating that such a thing as time travel is possible under any circumstances, while there is an abundance that it would, in fact, violate the conservation aspects of physics. It amounts to getting something from nothing... it can't be done. (And, lest someone bring up the Big Bang: no. That was not something from nothing. The original matter/energy of the Big Bang always was; it had no beginning, and it has no ending, it simply will be dispersed so widely that it will no longer be available for work, but will be a low-level radiant "heat" permeating the universe ... unless one accepts the "big crunch" as well -- mildly tenable, perhaps, but becoming less so with each new finding we make.)


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## SteveR (Sep 29, 2006)

Kbanfield, well I would argue human perception of time is actually what we call memory and imagination. And for sure memory and imagination do exist explainable by science in terms of biology,brain activity, neurons and all that. 

But again memories and imagination are not real things in that you could potentially touch them - but I accept this argument then heads for the  how many dimensions are there really (perceptions once again) and if there are more then we can only see in our perceived dimensions anyway. 

With regard to whether "Time" is a useful concept to advance knowledge then I think I would have to agree and say yes. It's a theory, and like all theory's they are a step (one way ot the other) to the truth, the reality. The motivation to develop our understanding is as you say very focused on our human values - long may it continue.



> The funny thing is...in 100 years...someone will travel back to read this conversation...



I hope so, so if anybody is reading this in the year 2106 or later then please post the truth and put us all out of our misery! 

Steve


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## SteveR (Sep 29, 2006)

Hi J.D.

I hear what you saying about the laws of physics. I would argue however that the fact that 'time travel' can't be explained by physics  is not the reason that it is not possible. As my argument goes I would say that physics simply describes what is real and not what is imaginary.

Hope that doesn't sound too pedantic!

Steve


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## Specfiction (Sep 29, 2006)

I think there are some misunderstandings here. 

1)Time, at least in at some level, is well understood in physics, especially thermodynamics and statistical mechanics.

2)Causality is NOT a physical conservation law like energy and momentum. It is put into all physical theory "by hand," because (like an axiom) it "seems" right to us. However, CPT “is” a conservation law (Charge Conjugation Parity, Parity, Time).

3)On the quantum level, time reversal is Ok! In fact, quantum states "require" that you have negative time or energy states for a complete description of a state.

4)There are some very hard to understand time/space reasons for believing that time travel "could" be possible given “extensions” of our current physics. These include models of accelerating frames in Minkowski space--this is very "speculative" and should be taken with a grain of salt.

The bottom line: the chances that macroscopic time travel is possible is almost zero--but not quite zero. That's why guys like Penrose, Hawking, Thorn, Gödel (maybe Vissor) and others keep coming back to it. It is a fascinating piece of fringe physics that cannot be totally discounted.


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## Dave (Sep 29, 2006)

carrie221 said:
			
		

> Okay if we have the technology to build time machines maybe we would also have the technology to build invisability cloaks


The US Army already has prototype invisability cloaks. There was an article in National Geographic magazine two years ago. Given a long enough timeframe who knows what can be invented.

When I said I didn't think we could have backwards time travel, as I said then that I was making a logical, philosophical argument against it. From a purely practical point of view, I'm sure science could find a way given enough time.

There is, however, a huge difference between making an atomic particle get younger, and a complete man. The same thing applies to matter transportation. There is also the problem of the energy that may be involved, already mentioned here.

I do love time travel stories though, especially the inconsistencies and paradoxes, so even if it is never possible, I will still want it to be.


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## j d worthington (Sep 29, 2006)

Dave said:
			
		

> I do love time travel stories though, especially the inconsistencies and paradoxes, so even if it is never possible, I will still want it to be.


 
Agreed.


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## steve12553 (Sep 30, 2006)

As an engineer deal with control system technology, I have many occasions to measure quantities and variables. As things get more accurate we use more significant digits. We measure more closely. But you know what? We never measure anything exactly. Everything in the world is rounded and less than perfectly accurate. Nothing is exact. Nothing will ever be exact. We will always get better and we will always come up with new and better ways until such time as somebody does something really stupid and nukes us back to the Stone Age. In the mean time, we probably will discover new laws, or new takes on existing laws, or new corollaries of existing laws of Science. It may take a thousand years. We might get a thousand years. We might travel in time. Only time will tell.*




*I couldn't help it.


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## j d worthington (Sep 30, 2006)

steve12553 said:
			
		

> Only time will tell.*
> 
> 
> 
> ...


 
No, you _could _... you just chose _not to_.


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## Harpo (Aug 21, 2007)

Harpo said:


> "Time-travel will never be invented because we can't see any time-travellers" goes the argument against.
> 
> But what if, instead of a time-machine being a machine which travels through time, it is a machine in which people can travel through time (within the operational lifespan of the machine).
> 
> ...




Is it too late for me to patent the idea?
Time Travel Machine Outlined - Yahoo! News

"Ori emphasized one significant limitation of this time machine—"it can't be used to travel to a time before the time machine was constructed." "

Does my post from last september count as copyright for the idea?


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## Interference (Aug 22, 2007)

Harpo said:


> Does my post from last september count as copyright for the idea?



Sadly, and I weep for you, but no, unless you've invented a time machine and can go back even further in time to be the first one to think of the idea.

I'm afraid your idea has been pre-dated and was the basis for the fictional fundament of Quantum Leap - it wasn't the basis for QL, just for its underlying limitation theme.

I think you'll find a semi-whimsical reference to the limitation of time travel to the life-span of the time machine in A Brief History.... and if I had a more encyclopaedic memory I'd tell you where else I've read the proposition, I'm sure I've read or read about or seen on telly the same or a similar notion.  It's certainly one I've been aware of for a number of years as I have tried to circumvent it in notes I made in 1995/6, and I _know_ I didn't come up with it myself.

Of course, fiction-wise, it's an annoyingly limiting concept.  If you've read any Jenny Randles, you might come round to the idea that time travel isn't such a big deal, anyway, and with the right conditions, anyone might do it.  Now, that's an idea I'd love to find out was real.


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## Urien (Aug 22, 2007)

You need to end this conversation now. In three days it leads to a schism in the etheric consciousness of the disaggregated and naive human sub-culture. Two days after that demented warpuls breach the D wall and infect all six toed people, violence ensues.

Only by hopping in my time kettle and steaming back to today can I save you all.


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## Interference (Aug 23, 2007)

Have you done it yet?

Have you done it yet?

Have you done it yet?

Have you done it yet?

Have you done it yet?


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## ghost8772 (Aug 27, 2007)

ok, on the original idea of time trasvel, possible or not.  and all that jazz.   there are too many possible things that have been shown could happen.  one COULD make changes, butterfly effect stuff, that alters the future from that point, creating what could only be called an alternate timeline from where the traveller started.  another view is that history is set, and that any changes that were made in the past HAD to be made, and if they weren't then the fabric of the universe would self-destruct, fire, brimstone, and all sorts of bad things would be incurred at that point.  another possibility would be that the person travelling back in time could not interact with the past,  but would be only an observer, with nobody being able to perceive his/her existence at that time..... hmmmm... maybe the reason for ghosts?


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## Harpo (Aug 27, 2007)

........ghosts in historical costume though?


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## Interference (Aug 28, 2007)

Harpo said:


> ........ghosts in historical costume though?



Personally, see no reason why not.  Even interacting with them might be possible.  Replays of a cosmic tape loop caught up in the granite - just realised I can't spell granate (or grannut, for that matter) - is one proposed explanation, but time slips aren't cosmologically impossible.  Spacetime is a whole bunch of stuff.  I hate to harp on about things we all know, but if we did meddle in our own history, even the history of our planet, would it matter a jot in cosmic terms?  Seriously, I doubt it.  Some say "There must be safeguards", but whom will these safeguards protect?  A bunch of carbon-based organisms whose time on this planet and contribution to the Universal All is as important as the next word I type.


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## ghost8772 (Aug 29, 2007)

historical costume?  maybe, maybe not.  after all fashion trends ARE cyclical.


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## Dave (Aug 30, 2007)

ghost8772 said:


> historical costume?  maybe, maybe not.  after all fashion trends ARE cyclical.


Hmmm! Maybe, it's an interesting proposition you make. Ladies dressed in green are common ghosts in Scottish castles - maybe this is a fashion trend of the future? But I think I can bring down your argument with the ghosts dressed in suits of armour - I'm not sure that they will be the de rigueur clothing for future time travellers.


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## ghost8772 (Aug 31, 2007)

well another supposition could be time travellers taking an effort to arrive surreptitiously,  so they DO travel in era clothing,  but need to have their machine calibrated.   maybe several attempted trips that drift the traveller into then back out of where they were supposed to go, but at the wrong time.  once they make it to the correct time they are either commited forever.  they die in that time or something like that.  operating backwards in time though makes it that they are sighted sfter their death on their journey backwards.  like I said in the original post,  to many ideas/theories/possibilities on what might happen if persons had the technology to travel at will through time.   

Of course the possibility that one would end up in hard vacuum with the earth being light years away  because they didn't travel in space during their travel in time must be considered also.


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