Topic: Why "The Time Machine" shouldn't work!

[Krathen Astreyk]

Sandman I would have to say you are inncorrect you are never actually time traveling as you aproch the speed of light time for you remains constant where as time for everyone else remains constant for themselves to you there time will speed up causing them to age when you have not.
You can not reach the speed of light because the closer you get to the speed of light the more apparent mass whatever your traveling in has there fore needs more thrust that it can't get. The only reason light travels at the speed of light is that it has no apparent mass.

[Jehenna]

current physics does not have a definition for the quality of time, while the quantity can be measured in relation to space (a second is a certain number of vibrations by a sodium isotope i believe, hence we actually define it in terms of distance moved)
i suggest you go do physics at uni if you really want to start understanding what little is known about time.

[Farseer_Nimliiost]

wow we have some smart people on eo!
personaly i try not to thing about paradox's and time travel it hurts my head

[BoyProdigy]

finally a good off topic post

if you guys are really into stuff like this read books by Dr. Michio Kaku he is a string Theorist. his offical site is http://www.mkaku.org/

he wrote this at his site on the subject about time travel

In H.G. Wells' novel, The Time Machine, our protagonist jumped into a special chair with blinking lights, spun a few dials, and found himself catapulted several hundred thousand years into the future, where England has long disappeared and is now inhabited by strange creatures called the Morlocks and Eloi.

That may have made great fiction, but physicists have always scoffed at the idea of time travel, considering it to be the realm of cranks, mystics, and charlatans, and with good reason. However, rather remarkable advances in quantum gravity are reviving the theory; it has now become fair game for theoretical physicists writing in the pages of Physical Review magazine.

One stubborn problem with time travel is that it is riddled with several types of paradoxes. For example, there is the paradox of the man with no parents, i.e. what happens when you go back in time and kill your parents before you are born? Question: if your parents died before you were born, then how could you have been born to kill them in the first place?

There is also the paradox of the man with no past. For example, let's say that a young inventor is trying futilely to build a time machine in his garage. Suddenly, an elderly man appears from nowhere and gives the youth the secret of building a time machine. The young man then becomes enormously rich playing the stock market, race tracks, and sporting events because he knows the future. Then, as an old man, he decides to make his final trip back to the past and give the secret of time travel to his youthful self. Question: where did the idea of the time machine come from?

There is also the paradox of the man who is own mother. (My apologies to Heinlein.) "Jane" is left at an orphanage as a foundling. When "Jane" is a teenager, she falls in love with a drifter, who abandons her but leaves her pregnant. Then disaster strikes. She almost dies giving birth to a baby girl, who is then mysteriously kidnapped. The doctors find that Jane is bleeding badly, but, oddly enough, has both sex organs. So, to save her life, the doctors convert "Jane" to "Jim."

"Jim" subsequently becomes a roaring drunk, until he meets a friendly bartender (actually a time traveler in disguise) who wisks "Jim" back way into the past. "Jim" meets a beautiful teenage girl, accidentally gets her pregnant with a baby girl. Out of guilt, he kidnaps the baby girl and drops her off at the orphanage. Later, "Jim" joins the time travelers corps, leads a distinguished life, and has one last dream: to disguise himself as a bartender to meet a certain drunk named "Jim" in the past. Question: who is "Jane's" mother, father, brother, sister, grand- father, grandmother, and grandchild?

Not surprisingly, time travel has always been considered impossible. After all, Newton believed that time was like an arrow; once fired, it soared in a straight, undeviating line. One second on the earth was one second on Mars. Clocks scattered throughout the universe beat at the same rate.

Einstein gave us a much more radical picture. According to Einstein, time was more like a river, which meandered around stars and galaxies, speeding up and slowing down as it passed around massive bodies. One second on the earth was Not one second on Mars. Clocks scattered throughout the universe beat to their own distant drummer.

However, before Einstein died, he was faced with an embarrassing problem. Einstein's neighbor at Princeton, Kurt Goedel, perhaps the greatest mathematical logician of the past 500 years, found a new solution to Einstein's own equations which allowed for time travel!

The "river of time" now had whirlpools in which time could wrap itself into a circle. Goedel's solution was quite ingenious: it postulated a universe filled with a rotating fluid. Anyone walking along the direction of rotation would find themselves back at the starting point, but backwards in time!

In his memoirs, Einstein wrote that he was disturbed that his equations contained solutions that allowed for time travel. But he finally concluded: the universe does not rotate, it ex- pands (i.e. as in the Big Bang theory) and hence Goedel's solution could be thrown out for "physical reasons." (Apparently, if the Big Bang was rotating, then time travel would be possible throughout the universe!)

Then in 1963, Roy Kerr, a New Zealand mathematician, found a solution of Einstein's equations for a rotating black hole, which had bizarre properties. The black hole would not collapse to a point (as previously thought) but into a spinning ring (of neu- trons). The ring would be circulating so rapidly that centrifugal force would keep the ring from collapsing under gravity.

The ring, in turn, acts like the Looking Glass of Alice. Anyone walking through the ring would not die, but could pass through the ring into an alternate universe.

Since then, hundreds of other "wormhole" solutions have been found to Einstein's equations. These wormholes connect not only two regions of space (hence the name) but also two regions of time as well. In principle, they can be used as time machines.

Recently, attempts to add the quantum theory to gravity (and hence create a "theory of everything") have given us some insight into the paradox problem. In the quantum theory, we can have multiple states of any object. For example, an electron can exist simultaneously in different orbits (a fact which is responsible for giving us the laws of chemistry). Similarly, Schrodinger's famous cat can exist simultaneously in two possible states: dead and alive. So by going back in time and altering the past, we merely create a parallel universe. So we are changing someone ELSE's past by saving, say, Abraham Lincoln from being assassinated at the Ford Theater, but our Lincoln is still dead. In this way, the river of time forks into two separate rivers.

But does this mean that we will be able to jump into H.G. Wells' machine, spin a dial, and soar several hundred thousand years into England's future?

No. There are a number of difficult hurdles to overcome.

First, the main problem is one of energy. In the same way that a car needs gasoline, a time machine needs to have fabulous amounts of energy. One either has to harness the power of a star, or to find something called "exotic" matter (which falls up, rather than down) or find a source of negative energy. (Physicists once thought that negative energy was impossible. But tiny amounts of negative energy have been experimentally verified for something called the Casimir effect, i.e. the energy created by two parallel plates). All of these are exceedingly difficult to obtain in large quantities, at least for several more centuries!

Then there is the problem of stability. The Kerr black hole, for example, may be unstable if one falls through it. Similarly, quantum effects may build up and destroy the wormhole before you enter it. Unfortunately, our mathematics is not powerful enough to answer the question of stability because you need a "theory of everything" which combines both quantum forces and gravity. At present, superstring theory is the leading candidate for such a theory (in fact, it is the ONLY candidate; it really has no rivals at all). But superstring theory, which happens to be my specialty, is still to difficult to solve completely. The theory is well-defined, but no one on earth is smart enough to solve it.

Interestingly enough, Stephen Hawking once opposed the idea of time travel. He even claimed he had "empirical" evidence against it. If time travel existed, he said, then we would have been visited by tourists from the future. Since we see no tourists from the future, ergo: time travel is not possible.

Because of the enormous amount of work done by theoretical physicists within the last 5 years or so, Hawking has since changed his mind, and now believes that time travel is possible (although not necessarily practical). (Furthermore, perhaps we are simply not very interesting to these tourists from the future. Anyone who can harness the power of a star would consider us to be very primitive. Imagine your friends coming across an ant hill. Would they bend down to the ants and give them trinkets, books, medicine, and power? Or would some of your friends have the strange urge to step on a few of them?)

In conclusion, don't turn someone away who knocks at your door one day and claims to be your future great-great-great grandchild. They may be right.

[Farseer_Nimliiost]

freeky yeah well hg wells was in the what like 50's??? a little off but pretty good
the best fictional time travel was the computer game serise the journyman project, its a trillogy, the journyman project, burried in time and a 3rd although i cant remember the title of that game but if anybodys ever played it, it is a pretty good discription of time travel

[Cheantoa]

I'm now going to quote myself. "Time does not exist."

Face it, it doesn't. The big crunch theory... I obviously got mixed up at some point, I thought that was the climax point of a big cycle our universe goes through... every billion quadrilliion quintilion sechtillion octillion nanmillion dodillion ya well you get the point. years. It is sorta like clearing a slate.. obviously I was wrong...

The possibility of multiple dimensions would already mean that there are infinite. Things just... work like that... I attempted to... solve that... it was so mentally taxing it wasn't funny and I wound up right where I started...

[Jehenna]

btw kage: mass of the universe is not known - hence we dunno if it'll go crunch or not. postulated its fairly close to critical but which side it's on... not to mention that we could spend our time making mass into energy and change it!

[Niran of Asha An]

the idea as our universe as being an oscillating form is getting popular i see...  but it's really inflationary.  As for time; I go with the quantum-spectrum belief that each second is a seperate universe with horizontal properties (it makes sense to me!)  that becomes a different freeze-frame in each "instant"  our minds react as we do to video, by filling in the gaps causing the illusion of "time."

[AdmanGroover]

There is no point in making a time machinebecause if we went forward in time to gain knowledge or technology then as we are using the knowledge now it would already exist well before the time you got it from, this means that the future would be changed so you could never go to the future meaning that you couldn't get the knowledge which means we are back where we started. Or the universe doesnt exist.
Also, if we went backwards in time thenwe would change preveous events which, at the worst, would stop the time machine being built, or stop you going in the time machine. Either way you never went in the time machine in the first place so none of the events happened.
Ah, the wonderfull world of paradox.

[StuffGuy]

wow some ppl here obviously arnt up to date on curretn science....

a what couple years ago now..... a group of scientist made a photon reach the speed of light.... the result? it got to its destination before they started sending it... the expirments been repeated a whole ton of times with the same result... so time travel into the past is possible =)

it has also been recently discovered that the universe appears to be accelerating away from the the point of the big bang... which according to the current theory of existence(fake name i just made up to explain everything in the universe)... dosnt make since, some guy at i think MIT has proposed a theory thats becoming more and more accepted its based on this:

1. It is known that in a vacum small atmoic particles appear and disappear in a time so small u need exponents to express it

2. Before the universe there was absolute nothing! not even space.... well in theory..... dont try imagining this space cuz its impossible because no human has ever expierenced anything like it

3. In theory.. this nothing would have the same appearances as there would be in a vacuum..... dont ask me why.... i cant remember the hull article......

4.If one of these things had the right mass and time... space time would curve in the correct way causing this one thing to inflate indefinatly

5. therefore the universe is born

[The Hive Custodian (Retired)]

First, I read that if you moved a black hole in a certain way, you could travel in time (but not before the time you created it).

Second, there are some ways that time travel is possible: you may just visit an alternate universe. You may or may not be able to get back. If you do, everything is how you left it. I don't know, though...

Does anyone believe in fate? 'Cuz I sure don't.

[TheMightyPikachu]

anyone care to pick apart the time machine idea for "back to the future"?

[Death_on_demand]

how do you know time will right itself? that is theoretical. In all truth, time righting itself makes no sense either. What would make it happen? and


StuffGuy. whoa freeky man! now that's sum speed... wait a minute. Okay in that case how far off is the scientific unit Light Year? I mean technically you just stated that we are seeing what happens with the stars before it happens, while every current theory holds that it takes light hundreds of years to travel the distance, it would in fact travel the entire distance before it was even emitted! That in fact would be a great astronomical thing indeed!

[Addinarr]

Well it HAS to right itself......otherwi se time would end right then and there, or become severely distorted.

Oh yes, I've got a question of the Photon into the past thing. After the photon was found, did they send it anyway? If they didn't......well....paradox!

[Cheantoa]

Photon passing speed of light and vanishing? What does that have to do with time? unless I read something wrong, that doesn't make all that much sense.

"wow, I can't find that Photon that we made pass the speed of light"
"It must've mysteriously travelled into the past!"
"or it escaped and we couldn't keep track of it"
"ya but my idea sounded better and will be more publicly acceptable"
"I see"

or at least that's what I'll bet happened. I didn't know that the speed of light was a signifigant speed... It's just the speed that light travels at... if something accelerated beyond that, you just wouldn't see it until after it happened, and it would look distorted, wouldn't it (cause not as much light would've been able to refract/reflect)... Someone enlighten me...

Note I said: You wouldn't see it until after it happened NOT It happened after it happened, which is what the result of seeing it would be...

[Lord Calamir]

a what couple years ago now..... a group of scientist made a photon reach the speed of light.... the result? it got to its destination before they started sending it... the expirments been repeated a whole ton of times with the same result... so time travel into the past is possible =)

You probably mean pass, not reach. Photons always travel at the speed of light.

Yes, superluminal movement is possible, but only for elemental particles and only over very short distances (tunnel effect).

[Cormer Lir]

The experiments in FTL movement are pretty weird.  Basically, there's some controversy over just what exactly is happening.  The tunneling experiments seem to imply that the front velocity MAY exceed the speed of light, but there's not really all that much PROOF yet.  They're still not sure what's happening.  And quite frankly it's all WAY beyond me.

In any case, I do have a link that's pretty easy to understand :  http://www.nasatech.com/WWWboard/messages/1232.html  

On the flip side, similar experiments have apparently resulted in SLOW light (seemingly part of the same principle).  Another link here: http://focus.aps.org/v3/st37.html

[StuffGuy]

oops.......

yeah they made it PASS the spead of light only when it passes does it go back in time.....

and they didnt get it to got must faster.... so the photon didnt go "that far" into the past

hey u know theirs some ppl in switzerland building a machine that might have the side affect of creating a black hole....., couple years ago their was these ppl that thought if they messed with the things that make um an atoms nucleus they could start a chain reaction to destroy the universe..... of course they had to test their theory..... good thing it was wrong..... u think they could ask before endangering the universe?

[Cormer Lir]

Sorry, still no dice.  The experiments you're referring allowed a sort of faster-than-light travel, but nothing ever went back into the past.  It simply arrived before it was supposed to, which is not the same thing.  

The idea that travelling faster than light will send you into the past is one of those things that still irritates me.  a.) present theory seems to exclude the possibility, and b.) even if you could somehow accelerate something beyond the speed of light, chances are it would simply go faster than light.  Not go back in time.

[Death_on_demand]

Well it HAS to right itself......otherwi se time would end right then and there, or become severely distorted.

okay well how can you be so sure it hasn't become twisted... how would we know? maybe that's what deja vu is! Lolz!

anyway it does not HAVE to right itself, nothing says that it would