Time travel? Maybe

May 11, 2010 By Dave Goldberg

Imagine that you're a science-fiction writer on a tight schedule. You'd like to play in the vast expanses of the universe, but you have too much scientific integrity to conjure up a warp drive or a DeLorean out of thin air. You're also concerned that your audience would get bored in the thousands of years that it would take for a spaceship to realistically travel the distances between stars. What you really need is a wormhole -- a shortcut through time and space. Best of all, unlike most science-fiction tropes, wormholes might very well be real.

Seventy-five years ago, and his collaborator, Nathan Rosen, submitted a paper to the Physical Review with the goal of unifying gravity and . Although they failed to discover a theory of everything, they did something arguably more much important: By creating the first theoretical model of a wormhole, Einstein and Rosen allowed science-fiction writers -- including Arthur C. Clarke, Madeleine L'Engle and the writers of "Babylon 5" and "Doctor Who" -- to explore vast stretches of space and time in the blink of an eye.

From the outside, an Einstein-Rosen bridge, as wormholes were originally known, looks a lot like its cousin, the black hole. And I risk having my official Physics Badge revoked if I don't tell you, ideally in a spooky voice, that "nothing can escape from a black hole -- not even light."

Einstein and Rosen made a very bold supposition: What if a traveler fell into the mouth of something that looked like a black hole, but rather than being crushed by a singularity at the center of a black hole, instead emerged from another mouth, potentially many light-years from where he or she started? This isn't as crazy as it sounds. Einstein's theory of general relativity -- our current working model for how gravity and space work -- has been confirmed with countless experiments. And, as ad hoc as it sounds, an Einstein-Rosen bridge is a perfectly valid solution to the equations of general relativity.

And it's not just a shortcut through space. In 1988, Caltech physicist Kip Thorne also showed something else: If you can build a wormhole, you can also turn it into a time machine. By dragging one of the mouths of the wormhole around space at nearly the speed of light, we can create a two-way tunnel connecting two points in time. Even better, you don't need to worry about mucking up history. A time machine built from the laws of general relativity is necessarily self-consistent, and thus your history will remain safely as you left it.

However, Einstein's original concept had a few flaws. For one thing, going through an Einstein-Rosen bridge, later theorists have concluded, would have to be a one-way trip, since one mouth always serves as the entrance and the other the exit. An even bigger problem with the wormhole Einstein envisioned was found in 1962, when John Archibald Wheeler demonstrated that an Einstein-Rosen bridge would collapse before anything, even a beam of light, could travel through.

Fortunately, wormhole design has improved considerably in the last 75 years. In 1988, Thorne and his students took up the problem of traversable wormholes, in large part because of a plea from his friend Carl Sagan, who was then working on the novel "Contact." Thorne found that it was theoretically possible to construct models of wormholes, but they would require the existence of as-yet-undiscovered "exotic matter" -- strange stuff that has less than zero mass -- to keep them open. Unlike Einstein-Rosen bridges, Thorne's model was bi-directional and, more important, stable.

This all might seem like good news, but the fine print on wormholes is pretty daunting when you get into it. For one thing, we've never discovered anything like the exotic matter needed to prop wormholes open, and for another, we're not sure how we -- or even a supercivilization -- could punch a hole through the universe to create one in the first place. Furthermore, the idea of time travel is so anathema to many respectable physicists that some, including Stephen Hawking, have proposed a "chronology protection conjecture," basically insisting that physics must somehow outlaw time machines in order to keep "the universe safe for historians."

Theoretical physicists have the luxury of being able to invent things that don't, or perhaps can't, exist. In the three-quarters of a century since Einstein thought up wormholes, we haven't come close to observing one, though we've gotten some fantastic science fiction in the bargain. It may be that in science fact, if we want to explore the galaxy, it would be much easier to do so without trying to rip up the fabric of space-time in the process.
___

ABOUT THE WRITER

Dave Goldberg is the author, with Jeff Blomquist, of "A User's Guide to the Universe: Surviving the Perils of , Time Paradoxes, and Quantum Uncertainty." He is an associate professor of Physics at Drexel University. He wrote this for the Los Angeles Times.

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User comments : 35

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mike352
4.2 / 5 (5) May 11, 2010
Nothing new at all in this article. Read Kip Thorne's book to see all this information, and lots more.
po6ert
2.5 / 5 (4) May 11, 2010
note discovery of an empty hole in space. a place where nothing is. located in a star nursery
SmartK8
4.3 / 5 (4) May 12, 2010
The problem is of course, that universe is hardly u-shaped as a folded paper example. The energy needed to bend it, is absurd. A near light speed travel will possibly affect the surroundings (because of the gravity wave it will generate). A wormhole is very unprobable, potentially unusable, and universe is probably nearly flat locally anyway. Warp travel is the way to go, but still may affect the surroundings if not done properly, and also requires some absurd requirements. My guess is we first need immortality, and then just go for it at some reasonable light speed factor. Only if immortality won't imply on us to be stripped of the emotions, like to explorer the new things. I'd say let's go to Mars first, and be reasonable.
Doug_Huffman
3.3 / 5 (4) May 12, 2010
What sort of conspiracy must be believed in for there to be no observations of timetravelers if timetravel is possible?
rbrtwjohnson
3 / 5 (3) May 12, 2010
I think spacetime theories are little flawed, because the science is unable to define what is time, the time could be more an effect than a cause, it could be an effect involving space and motion.
Question
3.6 / 5 (7) May 12, 2010
Time is just a measurement of change. The changes that take place originate in the micro world and happen at the speed of light in such huge numbers it would be for all practical purposes impossible to reverse.

It is safe to say time cannot be reversed and time travel is just a science fiction dream.

Hunnter
4.5 / 5 (2) May 12, 2010
SmartK8 hit it on the head, really.

If we ever figure our way around Higgs (if it exists), we could probably channel solar radiation in to mass to generate blackholes to potentially generate the power requirements for folding space.
But to do so in a way that wouldn't destroy the ship as well... that will be a huge barrier to overcome.
Hopefully we would have found out a way to generate a barrier to prevent gravity crossing it as well. Then we will have our very own blackhole drive that could last quite a while without having to be refueled.

It is either that or we will have to go the immortality route.
The difference between them is that we know the immortality route is possible now, just held back by stupid regulations at the moment.
Stem cells are already showing massive results from current tests.
Whether or not these could lead to cancers in later life is, sadly, going to take time.
Re-engineering the human genome to allow for better regeneration will help too. (not for us)
Ravenrant
4.6 / 5 (8) May 12, 2010
The title of the article is completely wrong, it isn't about time travel at all, it's about travel time. If wormholes are possible they will link two locations for instantaneous travel between them. You will enter one end now and emerge from the other now. No time travel involved.

Our understanding of time is wrong, that's why people think time travel is possible. There is no past and there is no future, there is only now. Now is simultaneous everywhere. You can slow the perception of time and you can slow the benchmarks we measure time with. We are all time travelers but it's a one way ticket to the future and in order to do so we and anything else must exist through every intervening instant, all the infinite nows between any 2 points in time.
Hunnter
1.7 / 5 (3) May 12, 2010
Time is just a measurement of change.


As far as we know, that is.
Time could be the expression of another spacial dimension, perhaps even several as one theory suggested a while back.
Think of a point moving through 4D space in the 4th dimension as an example. (obviously not anywhere near as simple as that)

Until we actually do these experiments at these speeds and energies, we simply cannot say 100% that time is just the rate of change.

Of course, if we did find this out, it would be one hell of a stake in the heart of free will...
Even the things we done to "change" the flow of time would have already happened anyway since it was the seeing the "future" that caused the effect.
I'm going to lie down...
Hunnter
2.3 / 5 (4) May 12, 2010
What sort of conspiracy must be believed in for there to be no observations of timetravelers if timetravel is possible?

I always find this one fascinating.

I'd think one reason could be that time travel is heavily restricted in the future.
And those that use it are mainly going to be researchers and historians.

Any who suddenly decided to go rogue and try screw with time could be known about in advance due to them already being capable of seeing their futures as well.
So to stop them, they could simply bring them back to the future before they even do anything, or remove their time travel device and leave them stranded, only to watch them remotely to make sure they really don't screw time up.
Thought-crime, essentially.
"The butterfly effect" is only really dangerous if it leads to huge changes within a short time jump.

Who knows, all those "crazy time travellers" could well have been time travellers at some point, and punishment is banishment in that time period.



Angus_P__Magilicutty
3 / 5 (3) May 12, 2010
First, right on, Author. I love the " ideally in a spooky voice..." thing! That's funny.

Personally, I like the multiple timeline idea, but that's really just a guess. We aren't yet in a great position to get time and space theory correct. There's a lot of work to be done still. Be patient. But if one enters a new timeline, or new universe when "traveling" in time, then that would explain not seeing time travelers-- we just aren't in one of the universes that has had a time traveler appear in it-- yet. In any case, there's no reason to give up hope yet. What would that do other than stop progress?
flhu
3 / 5 (2) May 12, 2010
I believe that IF time travel is possible, that the time machine would look like a a free-standing doorway. When you first turn this gate on, the furthest in the future you can go is when you eventually turn it off. As you look into the gate, the other side will appear to be moving backwards until the moment you turn the gate on.

But this whole thing starts with a BIG IF that I think is only hypothetically possible.
theophys
2.5 / 5 (4) May 12, 2010
I would think that there would be two reasons for nit seeing time travelers.
1) this isn't one of the more interesting time periods. There are no dinosaurs, Nazis or feudal battles.
2) if you were a time traveler, would you run around telling everyone? "hey, my name is bill and i was born in 3043" not exactly the best way to mingle with the locals
sender
1 / 5 (5) May 12, 2010
Maybe suspension of polariton bubbles in time displacement photofields could yield some more insight?
tjcoop3
1 / 5 (4) May 12, 2010
If you are really interested in the latest time travel research check the following site.
http://www.anders...ault.asp
douglaskostyk
3 / 5 (2) May 12, 2010
I would still like to see the space-time path of something exiting this Einstein-Rosen Bridge. Is there any time-like path that can do this? I think it is only one way, and virtual particle pair creation OUTSIDE the horizon is the only way out. The size of the horizon would need to be extremely small for a particle of the mass of a person to be created and this would be in the presence of a very intense flux of other created particles as the hole evaporates.
Jarek
5 / 5 (1) May 12, 2010
There is a lot of time travel consideration, while if it's really possible, there should be also much simpler possibility which would already turn our world upside-down - just sending information back in time, what shouldn't require any wormholes etc. - retrocausalibility is a natural aspect of (CPT conserving) quantum mechanics and can be literally observed in e.g. already confirmed Wheeler's experiment ...
http://en.wikiped...periment
Just imagine CPT transformation of free electron laser...
http://www.advanc...?t=11844
Alizee
May 12, 2010
This comment has been removed by a moderator.
Alizee
May 12, 2010
This comment has been removed by a moderator.
Simonsez
4 / 5 (2) May 12, 2010
There is no past and there is no future, there is only now. Now is simultaneous everywhere. You can slow the perception of time and you can slow the benchmarks we measure time with. We are all time travelers but it's a one way ticket to the future and in order to do so we and anything else must exist through every intervening instant, all the infinite nows between any 2 points in time.

Quoting Ravenrant for truth. This has long been my observation of the nature of time. We can record events that happened during a previous "now", but the fact is that they no longer exist.

Time can only be graphed on a single line, with the point of origin ever increasing by one unit of whatever magnitude you wish to define. The equation n=n+1 is about as close as we can get to defining "now" or "time". Everything is always moving and always changing.
droid001
2.5 / 5 (4) May 12, 2010
Nothing is impossible. We can create our universe as a computer model, and travel anywhere we want.
Alizee
May 12, 2010
This comment has been removed by a moderator.
rbrtwjohnson
3 / 5 (2) May 12, 2010
Photons and electromagnetic waves, cause-and-effect, which is the cause and which is the effect?
I think theories confuse cause and effect.
Alizee
May 12, 2010
This comment has been removed by a moderator.
Shootist
4 / 5 (4) May 15, 2010
note discovery of an empty hole in space. a place where nothing is. located in a star nursery


hardly a hole.
Newbeak
1 / 5 (3) May 16, 2010
Perhaps some UFOs are time travellers from the future.Some of the manoeuvres reported by witnesses are otherwise impossible to explain,such as instantaneous disappearance.
Has any commentator heard of Ron Mallett? He may have worked out a way to communicate with the future: http://www.physor...210.html
Skeptic_Heretic
5 / 5 (2) May 16, 2010
It is safe to say time cannot be reversed and time travel is just a science fiction dream.

No, time travel is a misnomer. And the concept that one can travel backwards in time is a fantasy.

Accelerated time perceptive relativistic travel is real and mathematically proved to be possible by all manners of validation. By exploiting time dilation one can move through time at greater "speed". It is, however, a one way trip.
Shootist
3 / 5 (2) May 16, 2010
Perhaps some UFOs are time travellers from the future.Some of the manoeuvres reported by witnesses are otherwise impossible to explain,such as instantaneous disappearance.
Has any commentator heard of Ron Mallett? He may have worked out a way to communicate with the future: http://www.physor...210.html


marsh gas
MorituriMax
not rated yet May 16, 2010
po6ert-"note discovery of an empty hole in space. a place where nothing is. located in a star nursery"

The title of that article still pisses me off. Thanks again to the writers at PhysOrg for another fine sensationalistic headline.

From the offending article in question:
"It is in fact a hole that has been blown in the side of NGC 1999 by the jets and winds of gas from the young stellar objects in this region of space."

So NOT in SPACE, but in the material of the nebula itself.

Raygunner
3.7 / 5 (3) May 16, 2010
I used to believe in time travel but ultimately decided that I had seen too much sci-fi. Since there is no compelling scientific evidence common sense tells me the past exists in our imaginations, in the fossilized evidence of decay around us, and in the echos of ancient light from the sky. The future resides in our imaginations. I am convinced that there is only a "now" and will always be a "now". The path to a universal grand theory of everything would be much easier if we simply stop trying to force the concept of time down the equations' throat. The universe is ultimately a much simpler place than we know - at least in some respects - and will not go out of its way to satisfy our desire to make a human illusion real.
bluehigh
3 / 5 (4) May 16, 2010
Indeed Skeptic Heretic, quite correct. We are in fact time travellers moving at a particular rate in the flow. It is demonstrably possible to alter our rate of flow. However, one property of time flow immutable in our reality is that it is uni-directional. No going back and a change in velocity will see you travel faster or slower in the time flow relative to others. You may watch others grow old or grow old while others stay young. Neither of these outcomes is tantamount to commonly considered travel to the future. Even in deep freeze suspended animation you must wait for the future to happen before you can be there.
bluehigh
1 / 5 (1) May 16, 2010
One practical outcome with enabling technology is that you could take a day off work and in a special zone have a (say) six week holiday. Conversely, you could leave home for one day and be at work for (say) six weeks. In either case, you would be away only one day (relative to others outside the special zone) but age an absolute six weeks. As usual the first applications of the new Time Flow Rate Management technology will be for military purposes. It is obviously a winning advantage, if one side can build a huge stockpile of weapons in what is a blink of the eye to opponents.
ZeroX
2.3 / 5 (3) May 17, 2010
.. We are in fact time travellers moving at a particular rate in the flow...
This is what I explained above - this particular speed is given by speed of omnidirectional expansion of Universe. So if we would expand faster, then our Universe does, we would travel into future, if we would collapse, we would travel into past. Gas expands by heating - when all his molecules are moving faster, then the time runs more slowly for them.
abhishekbt
5 / 5 (1) May 17, 2010
Is this a news article?
This article should be titled 'My fantasies with the wormhole" and go into the pyshorg forums or a blog post. Nothing less.
KBK
1 / 5 (1) May 17, 2010
The interesting thing about time is that it only exists across particles, not within them. Ie, it is an observation standpoint or vector. Quantum calcs and theory show this.

Since time exists as a external viewpoint (Heisenberg, etc),and flies as an arrow, this means that the external aggregate viewpoint of time flowing is one of particle interactives (time creation) having an asymmetrical aspect.

This is the core of Maxwell's full 20 equations in 20 unknowns, the ones that Heaviside and Lorentz discarded. An extremely minute and complex asymmetry in the system. Heaviside removed most of the asymmetry to simplify for electric motor design. There is ample evidence to show that Lorentz worked for and was supported by JP Morgan, and this, after Morgan saw Tesla's works and shut Tesla down.

The answer hides in returning to Maxwell's full original works.

Recent work in resonance of 'lasers on gasses' and solids thus creating huge cooling effects (!!!) shows the way through this mess.
Shootist
1 / 5 (1) May 17, 2010
I used to believe in time travel but ultimately decided that I had seen too much sci-fi. Since there is no compelling scientific evidence common sense tells me the past exists in our imaginations, in the fossilized evidence of decay around us, and in the echos of ancient light from the sky. The future resides in our imaginations. I am convinced that there is only a "now" and will always be a "now". The path to a universal grand theory of everything would be much easier if we simply stop trying to force the concept of time down the equations' throat. The universe is ultimately a much simpler place than we know - at least in some respects - and will not go out of its way to satisfy our desire to make a human illusion real.


Really? space and time fit so well together. After all, mass causes both to measurably distort.
Grave
5 / 5 (1) May 18, 2010
The future resides in our imaginations. I am convinced that there is only a "now" and will always be a "now".


i think time travel as people imagine is not possible (travel to a specific time-place and change things), because there is only "now", future/past are concepts that help human mind to understand the "now"

you COULD possibly see the past, to see you need information, which might be carried by light (if you use your sight) which travels at defined speed. if you can travel faster than this information you could SEE older and older information the faster you travel
-this is also the case of spatial jumps (wormholes, jumpgates/etc)

you cannot simply jump to abstract "future" since there is only "now",
you COULD "travel-one-way" to a future by using something like hibernation to let your mind/body sleep through predefined amount of time, you dont move in time, but your perception of time moves (time-capsule concept)
Skeptic_Heretic
not rated yet May 18, 2010
Now keep in mind, although I don't think it'll ever be possible, that doesn't mean time travel backwards is impossible. I jsut don't think anything could ever survive it.

It'd be akin to performing a cut and paste of information on reality, and reality doesn't like information loss as we can see from hypothetical blackhole physics.
ZeroX
2.3 / 5 (3) May 18, 2010
The situation, when quantum objects are traveling in time back and forth in small extent is quite common situation at the quantum level. The formation and evaporation of density fluctuations inside of fluids is basically the same process.

http://tinyurl.com/36fql36

The animation above illustrates the solution of time dependent Schroedinger equation for particle wave packet inside of potential hole.

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