Time Travel with Laser Ring: Dr. Ronald L. Mallett's Theory

[MaxPlank]

I've just finished reading the book "Time Traveler - A scientist's personal mission to make time travel a reality", by Dr. Ronald L. Mallett, professor of physics at the University of Connecticut. In this book Mallett explains a new theory to travel back in time using a laser ring, which creates frame dragging and closed loops in time, according with the Einstein's gravitational field equations. Did anyone of you read this book, too? Or does someone know something more about this theory, and what do you think of it?


And...another thing...Don't you think traveling back to the past would go against the law of thermodynamic, especially the law of entropy? What do you think...?

 

[Mentz114]

I haven't read the book, but I suspect the good prof's machine is based on a solution of the Einstein field equations which admit closed time-like trajectories. The source of such a space-time is no doubt a rapidly rotating ring of matter or energy.

There are many ways to get mathematical solutions that appear to admit time travel, but these are just mathematical speculations. It is unlikely that the energy could be found to create any of them. Also, we have no guarantee that all the predictions of GR are correct.

As you say, time travel seems to violate other laws of physics, even causality, so it doesn't seem to be possible.

And, if it were possible, where are the time travelers ?

 

[DaveC426913]

And...another thing...Don't you think traveling back to the past would go against the law of thermodynamic, especially the law of entropy? What do you think...?

There's nothing wrong with locally altering entropy - Earth life powered by the sun is a good example.

 

[Hernik]

But it would violate the conservation of energy, would it not? because if someone traveled to our time from the future, the traveller would represent an injection of energy into the current spacetime and a removal of energy from the future that the traveller leaves?

 

[JesseM]

But it would violate the conservation of energy, would it not? because if someone traveled to our time from the future, the traveller would represent an injection of energy into the current spacetime and a removal of energy from the future that the traveller leaves?

It wouldn't locally violate conservation of energy in any small region of spacetime (locally GR always reduces to SR), and energy is not always conserved globally in GR anyway.

But there are a lot of questionable aspects of Mallett's particular scheme for time travel--see the "objections" section of the wikipedia article, or the discussion in the previous thread here.

 

[MaxPlank]

I haven't read the book, but I suspect the good prof's machine is based on a solution of the Einstein field equations which admit closed time-like trajectories. The source of such a space-time is no doubt a rapidly rotating ring of matter or energy.

There are many ways to get mathematical solutions that appear to admit time travel, but these are just mathematical speculations. It is unlikely that the energy could be found to create any of them. Also, we have no guarantee that all the predictions of GR are correct.

As you say, time travel seems to violate other laws of physics, even causality, so it doesn't seem to be possible.

And, if it were possible, where are the time travelers ?

As for "where are the time travellers now?", Mallett sais: "My type of time-machine could only carry a time treaveller back to the moment the machine was turned on, and not one second before".
So it's easy to understand why there aren't time travellers visiting us now: because the machine is yet to be made...

Sorry for my english, but I am 17, from Italy...

 

[Mentz114]

As for "where are the time travellers now?", Mallett sais: "My type of time-machine could only carry a time treaveller back to the moment the machine was turned on, and not one second before".
So it's easy to understand why there aren't time travellers visiting us now: because the machine is yet to be made...

Sorry for my english, but I am 17, from Italy...

Your english is fine.

"My type of time-machine could only carry a time treaveller back to the moment the machine was turned on, and not one second before".

Sounds like it can only be used to go forward, then. I'll wait for the bi-directional family saloon with the automatic calendar.

 

[JesseM]

Your english is fine.

"My type of time-machine could only carry a time treaveller back to the moment the machine was turned on, and not one second before".

Sounds like it can only be used to go forward, then. I'll wait for the bi-directional family saloon with the automatic calendar.

Why do you say it can only be used to go forward? He said it could take the traveler back to the time the machine turned on. The same would be true of the hypothetical wormhole time machine, which could only take the time traveler back to the time when the time difference between the two wormhole mouths was created. All time travel solutions in general relativity work this way, I think.

 

[Mentz114]

JesseM,
If I wanted a machine to go back in time ( say to bet on a horse race) it would be useless to me. The machine would need to have been turned on before the race.

Don't tenses get difficult when talking about 'time-travel' ?

 

[JesseM]

JesseM,
If I wanted a machine to go back in time ( say to bet on a horse race) it would be useless to me. The machine would need to have been turned on before the race.

Sure, you can't go back to the 19th century or the dinosaur age or whatever with a GR time machine, but you can win on as many horse races as you want as long as they happen after you get the damn thing working! And once it is working, from your perspective it will definitely be "going back in time", even if the date you go back to is ahead of 2008 A.D. (a trip from 3000 A.D. back to 2999 A.D., say)

 

[Hernik]

But when I turn on my newly constructed time machine everybody (everybody who uses it from now on to the end of times to go back to the moment it first was turned on) shall have to instantly pop up right next to the machine, right? Otherwise history/time shall have to run over and over with new characters whenever somebody uses the machine in the future because they want to be part of the action in their past?

 

[JesseM]

But when I turn on my newly constructed time machine everybody (everybody who uses it from now on to the end of times to go back to the moment it first was turned on) shall have to instantly pop up right next to the machine, right? Otherwise history/time shall have to run over and over with new characters whenever somebody uses the machine in the future because they want to be part of the action in their past?

It's not true that everyone who uses a GR time machine always goes back to the date it was created, just that this is the furthest back you can go. With the wormhole time machine, you accelerate one mouth and then bring it back close to the other mouth, and the acceleration has now introduced some set time difference between the two mouths. For example, say this time difference is 3 years, and the two mouths were first brought together with this time difference in the year 2500. Then if someone travels through the right mouth in 2509, they'll exit out the left mouth in 2506. Then if they want to go back further they can just take a short trip through normal space to the right mouth in 2506, and then travel through it, exiting the left mouth in 2503. Finally, if they want to go back even further, they can again take a trip through normal space to the right mouth in 2503, travel through it, and exit the left mouth in 2500...but then that's it, they can't go back any further.

 

[Hernik]

I see. But if anybody in the future decides to take the machine as far back as possible they will have to suddenly appear when the machine is first turned on?

 

[JesseM]

I see. But if anybody in the future decides to take the machine as far back as possible they will have to suddenly appear when the machine is first turned on?

Yes, presuming the wormhole is wide enough to accommodate all these future travelers who want to go back as far as possible...if not, then they'll have to work out some system (or fight for it) to decide who gets the golden ticket!

 

[Hernik]

So if this one guy called John winns a timetravel in a gameshow and he decides it is cool and goes, then he will pop up in his own past and live alongside his first life? And then when "the original" John "again" reaches the time of the gameshow he'll win again won't he? And now there will be three of this guy.. But that is just the beginning, isn't it because this thing will go on for ever every three years? And so when the machine is turned on at first, an endless number of John will turn up? And he'll probably elect himself for president! Or did I go wrong somewhere?

 

[JesseM]

So if this one guy called John winns a timetravel in a gameshow and he decides it is cool and goes, then he will pop up in his own past and live alongside his first life? And then when "the original" John "again" reaches the time of the gameshow he'll win again won't he? And now there will be three of this guy.. But that is just the beginning, isn't it because this thing will go on for ever every three years? And so when the machine is turned on at first, an endless number of John will turn up? And he'll probably elect himself for president! Or did I go wrong somewhere?

Unless you believe in parallel universes or some notion that it's possible for a time traveler to "change the past", there'll just be two Johns in the past, not more. For example, if in the year 2500 John is 30 and he sees his 60-year-old self emerge from the future, and then they live alongside each other for 30 years, so in the year 2530 we have a 60-year-old John and a 90-year-old John, then the 60-year-old John will win the gameshow and go back through the time machine to 2500 and be the exact same 60-year-old future self that he remembers meeting when he was 30, living out the rest of his years normally until he's 90 in 2530.

 

[MaxPlank]

But, for example, what may happen, if the "old John", after winning the timetravel, goes back in the past, meet the "young John" and prevent him from winning at the gameshow...?

In my opinion there are too many paradoxes...I think time travel won't become a reality..

 

[JesseM]

But, for example, what may happen, if the "old John", after winning the timetravel, goes back in the past, meet the "young John" and prevent him from winning at the gameshow...?

Well, the most popular theory is that he wouldn't be able to, the timeline is just a fixed 4-dimensional structure that doesn't change. See the Novikov self-consistency principle hypothesis for example.

 

[peter0302]

And, if it were possible, where are the time travelers ?

Maybe they have a Temporal Prime Directive or something. Sheesh.

 

[MaxPlank]

So, this means that the "old John", who goes back to past, hasn't got free will, doesn't he?...Otherwise if he made decisions, he would change the course of the events...


I like the comparison with the Prime Directive...very good !

 

[JesseM]

So, this means that the "old John", who goes back to past, hasn't got free will, doesn't he?...Otherwise if he made decisions, he would change the course of the events...

I don't really see how any modern theories of physics could be compatible with "free will" (assuming free will means something different than just quantum randomness--and the Novikov self-consistency principle argues that even in QM, the probability of inconsistent events would always go to zero thanks to quantum interference).

 

[peter0302]

Now that's a depressing thought. In fact, I think it's wrong. I couldn't cite you a source but I recall when I first learned about QM, it was said that before QM, people thought that if you knew the location & velocity of every paritcle in the universe, you could predict the future perfectly. THAT would imply no free will. At least now, with the inability to know such detail, there is still the possibility that the future is not set and that we might have some influence over it.

 

[JesseM]

Now that's a depressing thought. In fact, I think it's wrong. I couldn't cite you a source but I recall when I first learned about QM, it was said that before QM, people thought that if you knew the location & velocity of every paritcle in the universe, you could predict the future perfectly. THAT would imply no free will. At least now, with the inability to know such detail, there is still the possibility that the future is not set and that we might have some influence over it.

Well, that's why I said "assuming free will means something different than just quantum randomness". But surely hooking a deterministic intelligent machine up to a random number generator (one based on random quantum events like radioactive decay, for example) doesn't give it "free will", since the random input is completely beyond its control and has absolutely nothing to do with its inner feelings, thoughts, or desires? This gets into philosophy, but I don't really think "free will" as most people conceive of it is even a coherent notion.

 

[eventhorizon1]

Time Travel

The reason time travel will not work in OUR universe is simple. If it were possible to time travel in our universe it would be very detrimental to evolution. Just think cells evolve only to be "time traveled" to the past and thus effect the evolution of the previous cells. you can say, i can travel back in time but any actions i do there won't effect the future that you came from unless you have some kind of parallel universe theory. I don't think that is the case. Since time travel would be detrimental to evolution of the human race, a race intelligent enough to ask the question "can we time travel" the mire fact that we can ask this question means we can not do it. If we could time travel i believe we would not have been able to evolve because something would have "time traveled" to thwart evolution at ANY POINT in the time line. Therefore it is only logical to point out that our Universe must be one that time travel is impossible in order for us to exist and ask the question.

 

[eventhorizon1]

the laws of physics if they support time travel, remember, would exist without a machine, just like you don't need an Atomic reactor to have nuclear fission. Ie the SUN.

 

[Ian Davis]

Regarding time travel, I think we make a mistake in treating it as possible only if we can do it. Time travel would be just as significant if light could go backwards in time, or if a positron was indeed an electron moving backwards in time as Richard Feynman proposed, or wave functions can go backwards in time as proposed by Professor Cramer.

http://seattlepi.nwsource.com/local/292378_timeguy15.html

The logic that time travel does not exist if we can't do it, is comparable to the logic that says that Alpha Centuri doesn't exist if we can't get there.

A question I have asked which none have yet answered relates to frame dragging in the vicinity of a rapidly spinning black hole. I have read that frame dragging in this context is a consequence of warping of space time so that time is no longer orthogonal to space. If that is indeed so I'd love an answer either way to the questions posed at:

http://cs.astronomy.com/asycs/forums/p/29882/361586.aspx#361586

regarding:

http://www.astronomy.com/asy/default.aspx?c=a&id=5606

It seems somewhat amazing to me that despite Einstein noting that no longer could one talk about space or time but only space-time, everyone describes the spatial drag experienced by one in the ergosphere of a spinning black hole (kerr space) but NOBODY that I have ever read thought to worry about what type of temporal effects occur to an object in the vicinity of a spinning black hole. Physically in such space ones velocity exceeds c, when standing still. I've read that one can exploit faster than c velocities to send messages backwards in time. And physically it is also possible to escape the ergosphere of a spinning black hole.

Why is it that everyone loves thinking about time travel using worm holes that require immense amounts of negative pressure to remain open? These are unconstructable, while pretty extreme examples of warped space time genuinely exists and could already in theory be exploited as a vehicle for probing the nature and reversability of time. Namely a black hole spinning at 98.7% of the rate needed to reveal their singularity, and this in the first black holes we've tried to determine the angular rotation of.

 

[DaveC426913]

In my opinion there are too many paradoxes...I think time travel won't become a reality..

This viewpoint has never sat well with me. I don't think that our finding paradoxes means that time travel likely isn't possible. It's a completely emotional argument.

We simp'y don't understand time and physics well enough to know whether it's possible in principle.

 

[Devoney]

Not that I have ever managed. Do I did had some experience... Just hear me out ;)

Not directly timemachine related yet:
Have you ever heard of astral projection? Interesting topic, not that I am an occultist or some kind. I just like to know everything interesting.
Astral projection (as you can find on the internet and many books) is a phenomenom to leave your body behind and travel only with your spirit on the astral dimension. Know that there are seven dimensions. (maybe the seventh heaven comes from this principle?) And the astral plane (plane is rather used then dimension in these kind of books) is one of them. all dimensions have their own characteristics. The first dimension is what we all are conscious in, the material world. The second is the etheral which has something already to do with your spirit but I don't know much about this one. The third one is the astral plane. Characteristic for this one is that it looks like the material one but everything is fluid and adjustable by thought. Also thoughts of you, and other people are energy waves that habitat on this plane. The nice thing comes now: you can travel to anywhere in the universe you want... The jungle, the moon, or whatever...

Now the timemachine stuff:
It is also claimed that you could travel in time while being here. The main principle described in lots of books is this one: Everything is one. And the higher in these 7 dimensions you get, the more it gets all one... And there is no barrier anymore by time if everything is one thing.

My experience:
It is hard to do this all conciously. Just like dreams, these memorys are very hard to remember and fade very easily. All of you have had out of body experiences or lucid dreams but just forgotten them. Dont believe me? Do you know in detail what you have dreamed last night? How could you know then if what I am saying is not true. Also dreams have somethings to do with the astral plane. Well I have had very short conscious out of body experiences where my legs where floating and my head still stuck to my physical self. Very odd experience together with sleep paralysis and the shocks when your different energybodys (physical and astral) separate are very impressive.

Theory:
I did not come up with this. It was in a book. The dimension we know is 3D. You can get over bariers by going up or down, left or right. In a 2 dimensional world you would only be able to pas a barrier (a line for example) by going left or right. If it is a closed line you can not get past it. In a 3D world you can, because different laws apply. Timetraveling is not possible in our physical world, therefore you have this other dimensions with other laws. Like can you materially read someones mind? Can you express feelings in physical matter? Thoughts and feelings are part of the astral world.


Maybe for yourself if you want to timetravel it would be interesting to study how to conciously get these out of body experience in the astral plane which you probably will learn earlier then a trustable build timemachine in this world will be invented.

Grtz Devoney

 

[Ian Davis]

Since posing the question I would point out the interesting research referenced from:

http://en.wikipedia.org/wiki/Delayed_choice_quantum_eraser

and the project proposed by Cramer at:

http://seattlepi.nwsource.com/local/292378_timeguy15.html

Ian

 

[gtimespace]

Hello MaxPlank,
I have not read the book Time Traveler, but I was fascinated by Dr. Mallett when when I heard him speaking on a local radio station here in Connecticut. It was the first time I had ever considered the possibility that either rotating matter or energy could be used to stretch or drag spacetime, let alone create a temporary microscopic worm hole or a tiny time machine. If I remember correctly, Dr. Mallett was only working on the scale of particles, not human beings, and even a particle size wormhole would require great energy. I do recall him saying that if a large enough time machine could even be created, it could only carry you back as far as the time it was turned on. It is interesting to note how he remained motivated by the memory of his father to continue his research work even after he realized that this limitation existed.

Brian Greene mentions several limitations to time travel in his book The Fabric of The Cosmos: Like our lucky lottery winner, John, Quantum vacuum fluctuations from the future could travel through the wormhole to the past, travel through ordinary time and space to the future, and continue entering the wormhole again and again creating an intense positive feedback loop that presumably destroys the worm hole, as was suggested by Stephen Hawking. Still, Greene attests that there is no conclusive proof of this. Moreover, if we are talking about a worm hole, a worm hole exists between two points in a previously nonexistent tube between space so to speak, so it's walls tend to rapidly collapse in on themselves unless some kind of exotic matter, shall we say negative energy, is pumped into keep it stable by shoreing up it's walls against space(time). Then there is the matter of what is at the other end of the worm hole. By accelerating the other end of the worm hole in space one could obtain a relativistic time difference that one will experience when they step out of the worm hole at the other end. This worm hole example which Greene attributes to Kip Thorn and his students at California Institute of Technology is easier for me to understand than encircling a very dense infinitley long cylinder studied by Kurt Godel and van Stockum, or a spinning particle within a spinning laser ring of light studied by Dr. Mallett, so I can not say if the limitations would apply and I will keep an open mind.