Time travel: four ways in which it could be possible

Some physicists are convinced that time travel is possible. Here's how we might move through the fourth dimension

LAST UPDATED AT 13:14 ON Fri 30 Jan 2015

Time travel has long been a science fiction staple – and an affront to common sense. But physicists have not yet been able to prove or disprove that humans may one day be able to manipulate the fourth dimension.

"Time travel was once considered scientific heresy," writes Professor Stephen Hawking in the Daily Mail. "I used to avoid talking about it for fear of being labelled a crank." However, these days he's far less cautious, admitting he believes human will one day figure out how to travel into the future.

How could time travel be possible?

"The question of time travel features at the interface between two of our most successful yet incompatible physical theories," explains physicist Martin Ringbauer. "Einstein's general relativity and quantum mechanics." Using both of these theories, scientists have suggested several ways they believe time travel could be possible – at least theoretically. These include:

Wormholes


Einstein suggested the theoretical existence of "bridges" through time and space – often referred to as wormholes. His theory has been further developed by numerous physicists including Stephen Hawking and Kip Thorne.

"The basic idea if you're very, very optimistic is that if you fiddle with the wormhole openings, you can make it not only a shortcut from a point in space to another point in space, but a shortcut from one moment in time to another moment in time," Professor Brian Greene, a prominent string-theory physicist, told Live Science.  

Problem
: No wormhole has ever been discovered, and even if it was, it would be far too small for scientists to manipulate for the purposes of time travel – measuring just a billion-trillion-trillionth of a centimetre across. They also pose a significant risk, bringing with them the threat of sudden collapse, high levels of radiation and contact with dangerous exotic matter, Space.com warns.

Wormholes are unstable because of the feedback created by this radiation, explains Hawking. In the same way that excessive feedback between a microphone and a speaker will fry the equipment, a wormhole is damaged by the radiation feedback it generates. "As soon as the wormhole expands, natural radiation will enter it, and end up in a loop," he explains. "So although tiny wormholes do exist, and it may be possible to inflate one someday, it won't last long enough to be of any use as a time machine."

Cosmic strings

Described as one-dimensional "cracks in the universe" and some of the strangest structures observed by cosmologists, cosmic strings could help us navigate through time. "Cosmic strings are either infinite or they're in loops, with no ends", explains J Richard Gott, an astrophysicist at Princeton University. "So they are either like spaghetti or Spaghetti Os."

They are thought to have formed billions of years ago, moments after the Big Bang, and because they contain such large amounts of mass, some scientists believe they could potentially "warp" space-time around them. "The approach of two such strings parallel to each other, will bend space-time so vigorously and in such a particular configuration that [it] might make time travel possible – in theory," according to Live Science.  

Problem: Again, cosmic strings only exist only in theory. "This is a project a super civilisation might attempt," says Gott. "It's far beyond what we can do. We're a civilisation that's not even controlling the energy resources of our planet."

Supermassive black hole

Described by Professor Hawking as natural time machines, black holes are so dense that they have a dramatic impact on time, slowing it down more than anything else in the universe. If a spaceship were to orbit a black hole, those on board would only experience eight minutes of time for every 16-minute orbit.

"Around and around they'd go, experiencing just half the time of everyone far away from the black hole. The ship and its crew would be travelling through time," he explains. "Imagine they circled the black hole for five years. Ten years would pass elsewhere. When they got home, everyone on Earth would have aged five years more that they had."

Problem: 
Black holes are more practical than wormholes because they don't present the same paradoxes and won't be destroyed by feedback. "But it's pretty dangerous," concedes Hawking. "It's a long way away and it doesn't even take us very far into the future.

Travelling at the speed of light

Another possibility would be travelling at the speed of light, a constant, finite speed of 186,000 miles per second. "If you go fast, your clock runs slow relative to people who are still," explains physicist Professor Brian Cox in the Daily Mail. "As you approach the speed of light, your clock runs so slow you could come back 10,000 years in the future."

Problem: According to the laws of physics, nothing can travel as fast as the speed of light – let alone a spaceship. Even the Large Hadron Collider, the strongest particle accelerator in the word, can't make protons move that fast. "If a proton did achieve that speed, it would need infinite energy to go any faster, and we don't have an infinite supply of energy," explains the BBC's Jennifer Ouellette. Also, the human body would not be able to withstand time travel at all, as travelling at nearly the speed of light would kill you.

 

Why time travel may be impossible by any means

Apart from physical problems, several paradoxes stand in the way of time travel. These include the "grandparent paradox", which has long flumoxed physicists and philosophers

As Science Alert explains, a time traveller could in theory prevent his or her grandparents from meeting, "thus preventing the time traveller's birth". This would make it impossible for the time traveller to have set out in the first place and kept the grandparents apart.

However, cosmologists believe they have figured a way around this by suggesting that there is more than one universe in existence – the 'multiverse' model. This allows for every possible version of an event to take place. The Independent's science editor Steve Connor gives this example: "a woman who goes back in time to murder her own granny can get away with it, because in the universe next door the granny lives to have the daughter who becomes the murderer's mother." 

This, and other paradoxes, are situations that "give cosmologists nightmares," writes Hawking. But, "even if it turns out that time travel is impossible, it is important that we understand why it is impossible," he says.

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IT WORKS!

I'm going to test out my time machine.
I'm setting it to go back 5 minutes.
See you when I get there!

There will never be time travel, because there is no such thing as time: There is only condition - and change. Time is an illusion in mind.

Elaborate.

gold star

The answer is always; "kill Hitler"

Things exist; they have condition as matter. They can change condition (as when something rots away; or, when someone crafts a machine from component matter). But it doesn't take "time." It's just a change of condition. Change itself is a condition. This is original thinking on my part. Someone once said to me: 'But what about a clock, and it's register of time?' A clock is a machine, and it doesn't know it's a "clock." The movement of hands are just a condition, and change of condition. "Time" for us is just a way to pit one condition against another, for convenience: We go to bed when the sun goes down, usually, and we have machines (analog, digital, etc.) clocks that gauge when the condition of Earth vis-à-vis Sun is favorable, and we plan activities based on that, and other matters of calendaring and clocks. Planning itself is a condition - and any condition of yourself against plan (and plan's potential) is just another... condition.

Not according to basic physics. What you're suggesting is nothing but a bunch of philosophical nihilist tripe. Time exists, and not just as a theoretical construct.

You've provided no reasoning for your position: It is yours that is tripe. As to basic physics, physics is the antithesis of "time" (in quotes, as it doesn't exist except as a convenience of mind). Keep the discussion on a civil plain.

Hello DogBoy;

Your post would have been funnier if you posted the "IT WORKS" first, and THEN the "I'm going to..."

:-)

Are you serious? Congratulations, you might just be the biggest idiot I've ever had the pleasure of conversing with. No, time is not just a construct. It can be affected by gravitational lensing. Clocks on the space station run faster than they do down here on earth, no matter how accurate the mechanism. If you're in one location one moment, and in another in another, I suppose that's just an elaborate deception fabricated by your mind, too, eh? Wow, deep thinker, I think you need to go back to the drawing board. Maybe start by staying awake through an entire documentary film?

Hmmm... you derive pleasure from talking with idiots? I think that, and your insulting nature, belies who the idiot may be. As to clocks running faster on a space station - means nothing - just another condition of a machine (the clock) suffering an impact to its workings by virtue of environment. I can put a clock underwater and make it stop. I guess I stopped time, huh? You have me laughing, and I like to laugh... so, thanks! If you want to have an intelligent conversation, debate, whatever, try being civil.

*Facepalm* You clearly didn't read what I wrote. The clock mechanism doesn't matter. The "relativity" in Special Relativity is time. I wasn't kidding when I said this was basic physics. What I've explained is what e=mc^2 means. This is all proven science, with hard math and real experiments behind it. The truth is, I'm a little embarrassed for you, having spoken on a subject you've obviously given a lot of thought but very little actual research. Clearly, I overreacted, but what you've suggested shows a very conceited worldview-to the point where it's a little offensive. To share an unresearched opinion in attempt to refute a scientific article smacks of extreme arrogance, and makes you look foolish.

"It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt." -- Mark Twain

I'm familiar with the Twain quote; one of my favorites. It's good to know you have self-awareness: "Clearly, I overreacted..." - you'll note that I am civil, and take genuine interest and pleasure in examining these sorts of things, and remain mature and reasoned (non-emotional; there are far better things to get emotional about).. As you say, "The clock mechanism doesn't matter." Indeed; the clock doesn't know it's a clock - it's a machine, and only our proactive assignation of numbers and our willful interpretation of them makes it a clock - in our minds. There remains only 1) Condition, and 2) Change. There is no Time... and Time Travel cannot be possible.

Wow. You claim to remain mature, and reasoned, yet you don't listen to reason. Time runs slower outside of a gravity well. It's proven fact. It's one of the basic facts of the universe. Yes, hours and minutes are constructs, but time itself is immutable fact. This isn't a personal opinion. Einstein himself had a theoretical idea for a time machine. It would require obscene amounts of matter to construct, but it's possible. You have probably stepped into a slightly higher gravity well within your lifetime, and experienced a minuscule form of time travel without realizing it. Astronauts come back to earth slightly younger than they would have had they remained on earth. I don't know what else to say. I could post countless websites explaining Relativity to you, but somehow I don't think you'd quite understand. Time is a physical reality. You aren't a time-traveling Shakespearean Touchstone by any chance, are you?

Don't let it get to you Jeremiah - plenty of other things to worry about.

I don't understand people like you, that's all. How on earth can you be satisfied with such a limited pool of knowledge, and not be eager to fill your brain with as much as it can contain? I'm often called arrogant, because I often inform people when they're mistaken, and yet people like you exist everywhere, spouting off uninformed opinions as if they were fact. If that's not the epitome of arrogance, how can you stand knowing there's so much you don't know? I can't stand it, myself, and I spend a great deal of my time trying to fill those gaps. I worry, because I see you as a microcosm of the deteriorating human condition. I wonder: can man be taught to love learning again? Is this arrogant ignorance cultural? Is it a recent affectation? Or are there genuinely different classes of civilization, and people like you really belong in the proletariat? That last one is really terrifying. I hope it's wrong. If it is, it means you've only been conditioned to be the way you are, and might one day learn to change. If not, I fear I may one day be looking into the government's mirror, preparing to be fitted with a rat cage.

I guess I must know something. I published a book, "I.T. WARS", that became an MBA-text used by 40 universities. It's still on Amazon, ranked at around a million and a half; it came out in '07. Helped me buy a nice house for cash. I guess I know a smattering of something. IT is very empirical, and requires a great deal of knowledge, especially at the level at which I practice. It's a discipline of mind that allows me to examine and realize all sorts of things. You'd probably find interest in the last chapter, "What's At Stake", which examines the threat of EMP.

And yet you know nothing about time or physics. And apparently had no interest in researching the field, preferring your own pontifications to reality. Why is that? Has your success in one field blinded you to your ignorance in others? I'm genuinely curious as to what your affliction is.

What people really don't realize about travel is that there really doesn't exist a fourth dimension. A dimension is something that describes a specific wave function that are believed to divide existing hidden doorways in the universes structure that act simultaneous as a whole function of what we call reality. So the question is asked Is there really a fourth dimension? Is light speed a universal speed limit for earth or does life goes on? The answer to this divine question is 'Life goes on of course'. What seems to happen may not really happen at all.
In the illustration A ship travels faster than light and observes things reversing backwards back into the past that it originated from like watching a clock run backwards or the origin of reality a its pathway it traveled from minutes before hand . But is that really what's going on? Is the universe of what's known as the fourth dimension really a dimension at all? What the captain sees in the ship traveling at time travel coordinates is reality passing up from itself. Or what Einstein's believes happens at that time. But in reality it doesn't happen that way at all. Your traveling so fast you can’t observe the scene anyways you can’t slow it down or speed it up what you will see if you could is momentum vibrating into shorter moment wavelengths of time that keep shortening more and more until reality reaches a point where it seems in the observation as though time has stopped. It will seem to stop but it doesn't - time just gets shorter and shorter and shorter as velocity in the ship gets faster and faster. The view Einstein illustrates as time traveling is just a description of the arrow of time running backwards. He explains it this way because 'light' seemed to him as a universal speed limit because it touches everything as being a special limit that can be directed for momentum and mass.(reality) The facts are - is that for time travel to happen as Einstein describes time stops. The ship is traveling at a velocity that it enters a new reality of time and space called a dimension and acts as a pathway between the past and the present. Directed by the description Einstein illustrates a time limit between the past and the present by means through velocity traveled in a spacecraft. But what he is observing is a physical illusion of what might be that happens if the speed of light were a speed limit - and the pathway by which it would continue if it were so. So a new question arrives. Does the universe really stop at light speed and does reality really assume back into the past? And is there really a dimension that will take you there? The answer is No. A wormhole takes you to a dead end because the space fabric tension projectiling the planets round upon won't allow passage through it. Space acts as a surface grid which not even planets or galaxies are allowed passage. Secondly, time is a human developed measuring techique for mathematics to measure a specific length using time for an equation. There exist no doorway back into the past. Spacetime as Einstein describes is a directive in a mathematical measurement that if placed on paper makes the universe past, present and future simultaneous. The passage through 'spacetime' does not take you through TIME itself at least not backwards into the past. The fastest pathway to china is straight through the earths core to the other side (the shortest distance) allowed to travel at the fastest time it takes to get there but it does not make the path a fourth dimension of space and time. Space and time are exactly that space and time. They do not entangle together to form a path in reality a reality that has sat for the universe for billions of years. Taking that shortest root to somewhere does not make that root a new dimension it only makes it that fastest root to the place of travel. Time travel in this respect means a passage through reality (matter/mass) from an out of the way manner and make reality intervene backwards or forwards and changing the universe's direction just for you the pilot of the ship even if it only means using just one of the planets time cycle like earths in relativity. It means devising a devise that changes the direction of (not time but reality (matter/mass) materialism that will allow you to pass through the realm (the universe) in a different direction of passage that already is permanent and exist in the structure of the universe is already. It means changing the way the material universe works and I don't think that is really possible. Time might be able to be used as a coordinates for such a thing but making it reality is beyond this day and age. Imagine viewing a passage way that allows to observe reality (atoms) and such structured passing backwards instead of forwards at a specific momentum. A vehicle for such a journey would have to be part of the realm and it doesn't seem to me that that is a passage of a new dimension. Does it you? Things vibrate towards a specific direction and obtain a specific result because of it. This I don't think can actually be even temporarily changed for even just a second of time. Traveling from place to place in everyday life is just that and the coordinates of time it takes for the ride is predetermined by reality and to be able to travel through this predetermined cosmic clock (or atomic clock which one) is really fast. This doesn’t mean that time travel isn’t possible. It only puts a lid of facts about the speed of light.
By: Rodney Kawecki 2014.07.07 yr.

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