Mr Smith,

I do check on all FQXi discussion threads as often as I can, particularly of course this thread! I did my own quick search through the essay threads and also drew a blank. Lurking in the back of my mind is a vague recollection of seeing an Einstein quote to that effect. I will continue searching when I can, as it is important of course to see what context he was talking in, if indeed he said it!

At the moment I am concentrating on possible extensions to Bohmian Mechanics which attempt to make it relativistic & Lorentz invariant so that it can apply at all scales & therefore to our concept. Still getting my head around that static hydrogen electron too! Surely it can't be right!!!

Cheers

Mr. Johnstone,

It's comforting to read that you also have at least a vague recollection of having seen the Einstein quote. I'm hoping my subconscious didn't simply fabricate it from whole cloth. Have been reading so many essays and threads recently that things have begun to blur as to exactly where I've seen what. I'm definitely kicking myself for not having paused long enough to make a careful note of where I saw that particular quote, however, assuming I did in fact see it. Lesson learned; haste makes waste. Perhaps other fqxi denizens who stumble across this thread will have better memories and thus be able to help us sort it out.

Good luck with your other related pursuits!

Cheers,

jcns

Mr. Johnstone,

Just a very quick comment on the static electron: I haven't been following your deliberations on this so am hesitant to comment without knowing the background, but is it possible that you're looking at some sort of standing wave phenomenon which might be indistinguishable from a "static" electron? Just a thought, but I suspect that either this is not germane to your context or else you've probably already considered and dismissed it.

Cheers,

jcns

For readers of this thread who have more than a passing interest in "the problem of time," I'd like to offer links to a couple of papers which are highly relevant and thought provoking.

1. 'A Possible Solution to the Problem of Time in Quantum Cosmology' by Stuart Kauffman and Lee Smolin, 5 March 1997, http://arxiv.org/pdf/gr-qc/9703026v1

2. 'The present moment in quantum cosmology: Challenges to the arguments for the elimination of time' by Lee Smolin, 30 August 2000, http://arxiv.org/pdf/gr-qc/0104097v1

Enjoy!

jcns

Mr. Johnstone,

In the first of the two papers I referenced in my previous post one may find the following:

"One has simply a set of rules by which a set of possible configurations and histories of the universe is constructed by a finite procedure, given any initial state. In a sense it may be said that the system is constructing the space of its possible states and histories as it evolves.

"Of course, were we to do this for all initial states, we would have constructed the entire state space of the theory. But there are an infinite number of possible initial states and, as we have been arguing, they may not be classifiable. In this case it is the evolution itself that constructs the subspace of the space of states that is needed to describe the possible futures of any given state. And by doing so the construction gives us an intrinsic notion of time." (page 11)

Is it simply my fevered imagination working overtime or is it possible that the above is simply a more rigorous way of stating that a particular time is identically equivalent to, and is completely defined by, and only by, a particular configuration of the universe, and that "the flow of time" is nothing more and nothing less than the evolution of the physical universe?

Inasmuch as we tend to see these issues from a similar perspective, I'd welcome your thoughts here. In other words, sanity check appreciated. Thanks.

jcns

Mr. Smith,

I enjoyed reading your essay. I am a believer in a real, objective Universe, otherwise said "what we see is what we get", no extra dimensions, no dark energies or or dark matter... only phenomena waiting for a simple explanation. That leads me to believe that reversing the time falls in the same category with the assuming that objects may exist with negative dimensions ... Like you mention in the paper, it is difficult enough to find out what in fact are we trying to reverse? How you "reverse" time for atoms which are part of a bigger picture? It is obviously that even if it is very weak, we are gravitationally bound to the center of the galaxy. Are we going to "reverse" that too? Is there a cutting point for those interactions? I think that the entire speculation comes from confusing "slowing down" with "going back."

I am also a big fan of John Wheeler. I wholeheartedly agree with his comment about time you quoted in the essay:"We don't realize we're the source of the puzzle because we invented the word." I am not an expert in physics or mathematics, but I have been using both in my practice. As an engineer I am always translating this quote into a more practical "just because you can, doesn't mean you should..."

Best regards and best of luck with your essay.

Mr. Coman,

Thank you for your kind and encouraging words. I like your "translation" of Wheeler's quote. Sounds like good advice. Wheeler certainly is one of the most frequently quoted of all modern physicists, along with Einstein of course. He represents a now mostly vanished generation of physicists who we revere for their humanity as well as for their thirst for a deeper understanding of the universe. One of my greatest treasures is a personal letter which I received from Mr. Wheeler in reply to a monograph I'd mailed him. I'd mailed copies of the same monograph to probably dozens of younger physicists, but Mr. Wheeler was one of the very few who took the time to reply, and a most gracious reply it was.

Good luck with your essay and with your ongoing professional efforts, too!

jcns

Mr Smith,

I think your sanity is probably safe! Without knowing the context ie the "finite procedure" these statements relate to, they would seem to be consistent with an evolving configuration based description of reality, with future "time" being dynamically determined, rather than the "block Universe" description of GR with time being "moved through" by massive bodies. I think I may have read both of those papers at some stage, but now might be a good time to review them when I can. I know Lee Smolin seems to have changed his mind about the reality or at least the "utility" of time in recent years and that seems to be borne out in the title to the second paper.

Regarding the mysterious Bohmian static electron, it seems to have more to do with the wave function for the hydrogen ground state being real valued (ie not complex). I must say at this stage that the explanation & justification for this seems just as mysterious to me as the mysterious quantum behaviour Bohmian Mechanics is supposed to explain!! But it just may be beyond me to understand the technicalities, at least at the moment. It is probably trivial in the wider application of the theory anyway.

Cheers

Roy J

Dear J.C.N. Smith,

The mainstream physics affirms that time travel is impossible. All physics textbooks prove the impossibility of time travel. And you prove the same impossibility of time travel. Do you think such essay advances the physics? The present essay context looks for ideas at the limits of physics. Do you have any ideas at the limits of physics? The most part of scientists are sure that time travel is impossible and they do not need in additional proofs.

Imagine that I'll write the essays: On the impossibility of violation of energy conservation laws; On the impossibility of violation of Albert Einstein's general theory of relativity; Maybe I mist write the essay: 'The Newton gravitation theory is true'. All these papers do not advance physics, they repeats the known statements only. In the same way, your essay repeats the known already statement that time travel is impossible.

Your arguments from essay are non-convincing:

1)You wrote 'a carbon atom which once resided on the tip of Cleopatra's eyelash may now reside on the tip of your eyelash'

Time travelers use the Everett's multiverse theory to travel in past. In this case your arguments fail. A carbon atom which resided on the tip of Cleopatra's eyelash is from the Universe number one whereas another carbon atom is from universe number two. There is no paradox here.

2) Your arguments about the particular time and configuration of universe also do not work for case of multiverse theory;

3) You wrote 'we believe that it is made up, of the same bits and pieces which formerly were arranged very differently to include dinosaurs' If the observer jumps from one universe to another, all your arguments fail.

Since each new configuration of Universe replaces the previous configuration, consequently it is a physical process. In order to travel in time we must control this process.

Mr. Leshan,

Thank you for your comments.

You wrote, "All physics textbooks prove the impossibility of time travel." If this is true, can you please explain for me why numerous respected physicists continue to speculate about the possibility of time travel? References 1 and 2 to my essay were intended merely as representative examples of this genre, not as an exhaustive list.

Your arguments invoking Everett's multiverse theory clearly hinge on that theory or other, similar multiverse theories being generally accepted as correct, which I believe is not the case. Until stronger evidence is presented for the existence of multiverses, I'll continue to focus my attention on the one (and only) universe which I'm able to observe.

You wrote, "Since each new configuration of Universe replaces the previous configuration, consequently it is a physical process. In order to travel in time we must control this process." Yes, I totally agree with you on this point. As soon as we devise a way to manipulate and control the configuration of the entire universe (e.g., if we could arbitrarily return the entire universe to a former configuration, for example), then time travel might indeed be possible. Good luck with this project! I hope that when you've figured out how to accomplish this feat you'll explain it in an essay here at FQXi.

jcns

Mr. Johnstone,

Reassuring sanity check much appreciated. Regarding the mysteries or Bohmian Mechanics, I freely (if regretfully) acknowledge that the technicalities of this topic currently exceed my grasp. Good luck with your investigations, especially as they apply to the problem of time. Any resulting conclusions which can be explained in lay terms will be most welcome. Thank you.

Cheers,

jcns

Re: "All physics textbooks prove the impossibility of time travel".

I think it would be much more accurate to say that most physics textbooks describe paradoxes that *should* preclude time travel and that the majority of physicists agree that it should not be possible, however I don't recall seeing any proofs. The whole question of how to treat time in current theories is still open. In fact, the "mainstream" theory for the macroscopic world is General Relativity, a theory which allows solutions giving closed time-like curves, wormholes, singularities etc, all of which are undesirable and can in principle allow time travel/causality violation. Einstein himself didn't realise the full implications of his theory!

Everett's Relative State theory ("many worlds") was a response to the Copenhagen "observer created reality" weirdness, but when used as an "escape" from causal violations (eg Grandfather Paradox), itself relies on time travel via GR to be possible. The challenge is to falsify these solutions or find a way via quantum gravity/cosmology or even string theory to avoid them. This is an ongoing process.

So, whilst "mainstream physics" may "affirm" that time travel is impossible, the "proofs" are not yet there. Clearly stated principles relating to the nature of time such as that put forward by Mr Smith in his essay, whilst perhaps already intuitive, are I think a necessary step on the way to a full understanding of reality. We know that GR is incomplete, as is quantum mechanics and until they are either unified or replaced by something better, we will not have the evidence we need to prove the impossibility of time travel.

Cheers

RoyJ

Mr. Craft,

I'm glad you enjoyed the essay. Your question about the "duration" of the present time is a fair one; I wish that I could give you a good, simple, straightforward answer, but I can't. I suspect that our notion of "duration" is a relic, a holdover from our old, conventional ways of thinking about time, but even this is not one hundred percent clear to me.

The universe is what it is. We observe that it evolves; the challenge is to describe that evolution without invoking the old, separate, conventional quantity of time in the process of doing so. As always, the devil is in the details. Fortunately, people who are much smarter than I am are giving these issues a great deal of thought even now. Aside from cheering them on, I'm afraid I've not been of much help in this regard.

Please do check out reference 4 to my current essay if you ever have time; it looks at some of these same issues, but from a somewhat different perspective which may shed additional light on the topic.

Mr Smith ,

You say

Wheeler certainly is one of the most frequently quoted of all modern physicists, along with Einstein of course.

I prefer Mr Bohr ...it's the main piece ,and his son of course .

But I recognize his extrapolation and some interesting mathematical imaginations .

Mr Tegmarg probably is a fan of Mr Wheeler .

I think what the sciences aren't there for a competition about fundamenatls because fundamenatls dislike the

Bohr have formed Mr Wheeler ....and I think it exists thus two sciences systems .One harmonic ,the other chaotic .But of course I don't explain more about this reality.It's not necessary for my health hihihi

The spirituality of Bohr and Einstein are the main pieces of our fundamentals .

Let's take the multiverses or the uniqueness ....the electric energy or the H bomb ......in fact it's a real problem for sceinces and its evolution.

IBM and Princeton in the city of the speculations in short time with the long term funds????

The problem thus is not the sciences but an other thing ,its name is the monney .....

Some people have the fear to loose their capitals and these capitals are since a long time on Earth ....the family system and its habits without consciousness .

I think what the harmonisation must be fundamenatl in all centers of interest and that for all ,the individual being and the humanity more its complexity of creations .

But it's just a suggestion of course .

Sincerely

Steve,human on Earth

The past is to learn ,the present to act and the future to evolve ....

Time is a constant of evolution towards harmony .All chaotics systems shall disappear with or without our approbation ,our proposal ,our whishes .

The Faith is universal ,and any human systems can contredict that .

Sincerely

Steve

Dear J.C.N. Smith,

I published a Time Travel method here:

Can you find any errors in this Time Travel method? Pay attention that my method allows time travel to future only. I wrote in my paper that time travel in PAST is possible if multiverse theory is true only.

If multiverse theory is wrong then my theory allow time travel to future only.

The modern physics allows time travel into future. It does not violate causality and conservation laws. Thus Time travel is possible!

Sincerely, Leshan

Hi Leshan ,

You are incredible .hihihi a real catalyzer of threads .You are likeable in fact .

Sorry but it's impossible to travel in Time ,the dilatation of Time by Einstein is so complex ,but never he said what it was possible .

He said what the space and time are linked and the space due to the gravity changes and produces gravitational waves .

It's totally different .

Furthermore the multiverses ideas are against the uniqueness and its equation .

Only one is sufficient to explain all in respect with our creator of course .

On the other side for the future it's an other question indeed but if it's possible ,it's in a very short space and during a short moment thus not necessary .But it's just my opinion of course.

I reread your papper about time travel ,you are very strong in fact and in fact relevant .

In your essay ,why did you say what the waves are infinites .

I don't understand really dear Leshan ,in the physicality ,nothing is infinite ,perhaps the space due to our human extrapolations but the Universe and its laws are finites .

In fact it's not serious what the multiverses and time travel are falses ,it's just fundamental .

Why to travel in time .....it's more essential to travel in space in fact No ?

Regards

Steve

Dear Steave,

Outside of Universe does not exist time as a property. Therefore if we send a body outside of universe, we 'froze' a body, for example for 100 years. Outside of Universe a body experiences no time because time dilation is infinite. After 100 years a body reappears again in the real universe. It is time travel to future. No physical laws are violated.

You wrote: In your essay, why did you say what the waves are infinites.

I examine there how to travel in time using quantum mechanics. All bodies are particle-like objects with wavelength l=0. For time travel we must transform a body into a wave with l= infinity due to a body disappears. Then its wave-function collapse and this body reappears in another place or time

Yours Leshan