Falling Through the Cracks

[RainmanTime]

The grandfather paradox violates causality and cannot exist, so why would you want me to say that it is true?

Maybe because you were using the GP in your argument above for string theory? You held up the GP as being somehow important enough to define a solution. So if it cannot exist due to causality violation, then it matters not whether string theory can "solve" the GP. It is a problem that does not exist, so it does not require a faux solution, yes?

RMT

 

[Twighlight]

quote:

"
Now for the physics

In my experience, people whose posts are invariably little more than quotes.....generally do so because they fundamentally do not themselves understand the subject matter to a level where they can argue 'off their own bat' so to speak - but instead feel the need to qualify their lack of knowledge with ' Professor XXX supports everything I say '.

 

[RainmanTime]

but instead feel the need to qualify their lack of knowledge with ' Professor XXX supports everything I say '.

I'm a professor (of aerospace engineering)... and I support everything I say!!! WOW! /ttiforum/images/graemlins/loveit.gif

RMT

 

[Twighlight]

and I support everything I say!!!

Ah ! Now would be a great time for me to post the 'Homer Simpson Theory Of Donut/Teacup Equivalence'. A topological PROOF that eating tea cups is no different to eating donuts. Then I'll start my class action lawsuit against the Simpsons makers for discrimination against tea cups. I'm sure I'll have your full support...

 

[khan2012]

Portals are continually being created via mental nexus points in space-time. It becomes possible to fall through the cracks into alternate realities and future/past scenarios.

The grandfathers paradox is not ..."true", it simply cannot exist.

http://mkaku.org/home/?page_id=252

quote:

"
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

"

 

[Packerbacker]

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

But just on the outside chance they might be testing the grandfather paradox, keep your shotgun within reach!

 

[Darby]

Maybe because you were using the GP in your argument above for string theory?

You're on the right track, Ray. String or any other QM situation won't resolve GP. Leptons and hadrons could care less about grandfather and grandson. All they care about is that their numbers are conserved plus an assortment of other conserved quantities associated with them. And they are absolutely indistinguishible from one another. When and where they appear in some configuration space, alive or dead, the particles making up gramps and grandson will just continue on with their existence oblivious to the fact that someone somewhere perceived a paradoxical situation. Neither their existence nor an "observation" as defined in QM requires an intelligence to be present to resolve the interaction.

Applying a classical situation, the Grandfather Paradox, to a strictly quantum interaction, the state vectors of two or more individual sub-atomic particles, is mixing apples and oranges. Applying it to general relativity, a classical theory of physics, is appropriate.

 

[RainmanTime]

Portals are continually being created via mental nexus points in space-time. It becomes possible to fall through the cracks into alternate realities and future/past scenarios.

Not sure what this is in response to, because I cannot presently view your JPG you embedded inside the quote block. However, these are highly non-deterministic words that mean little (perhaps nothing) in a scientific discussion. "mental nexus points in space-time"?

You are arguing from a hypothetical standpoint, from what I can tell. I am asking for repeatable (and veridical) science.

RMT

 

[khan2012]

http://www.dailygalaxy.com/my_weblog/2008/01/parallel-univer.html

quote:

"

Their research shows that Everett was indeed on the right track when he came up with his multiverse theory. The Oxford team, led by Dr David Deutsch, showed mathematically that the bush-like branching structure created by the universe splitting into parallel versions of itself can explain the probabilistic nature of quantum outcomes.

The work has another strange implication. The idea of parallel universes would apparently side-step one of the key complaints with time travel. Every since it was given serious credibility in 1949 by the great logician Kurt Godel, many eminent physicists have argued against time travel because it undermines ideas of cause and effect. An example would be the famous “grandfather paradox” where a time traveler goes back to kill his grandfather so that he is never born in the first place.

But if parallel worlds do exist, there is a way around these troublesome paradoxes. Deutsch argues that time travel shifts happen between different branches of reality. The mathematical breakthrough bolsters his claim that quantum theory does not forbid time travel. "It does sidestep it. You go into another universe," he said. But he admits that there will be a lot of work to do before we can manipulate space-time in a way that makes “hops” possible. While it may sound fanciful, Deutsch says that scientific research is continually making the theory more believable.

"Many sci-fi authors suggested time travel paradoxes would be solved by parallel universes but in my work, that conclusion is deduced from quantum theory itself."

The borderline between physics and metaphysics is not defined by whether an entity can be observed, but whether it is testable, insists Tegmark.

He points to phenomena such as black holes, curved space, the slowing of time at high speeds, even a round Earth, which were all once rejected as scientific heresy before being proven through experimentation, even though some remain beyond the grasp of observation. It is likely, Tegmark concludes that multiverse models grounded in modern physics will eventually be empirically testable, predictive and disprovable.

"

 

[Twighlight]

He points to phenomena such as black holes, curved space, the slowing of time at high speeds, even a round Earth, which were all once rejected as scientific heresy before being proven through experimentation, even though some remain beyond the grasp of observation. It is likely, Tegmark concludes that multiverse models grounded in modern physics will eventually be empirically testable, predictive and disprovable.

No that's rubbish. The veracity of one idea, or whether people disbelieved it, has no bearing whatever on the veracity of any other idea. Simply arguing ' ah well, they laughed at XXX theory' does not prove YOUR theory right !

 

[khan2012]

http://space.mit.edu/home/tegmark/multiverse.html

quote:

"

I survey physics theories involving parallel universes, which form a natural four-level hierarchy of multiverses allowing progressively greater diversity.

* Level I: A generic prediction of inflation is an infinite ergodic universe, which contains Hubble volumes realizing all initial conditions - including an identical copy of you about 10^{10^29} meters away.
* Level II: In chaotic inflation, other thermalized regions may have different effective physical constants, dimensionality and particle content.
* Level III: In unitary quantum mechanics, other branches of the wavefunction add nothing qualitatively new, which is ironic given that this level has historically been the most controversial.
* Level IV: Other mathematical structures give different fundamental equations of physics.

The key question is not whether parallel universes exist (Level I is the uncontroversial cosmological concordance model), but how many levels there are. I discuss how multiverse models can be falsified and argue that there is a severe "measure problem" that must be solved to make testable predictions at levels II-IV.

"

 

[Twighlight]

Khan...

Are you actually capable of a post that isn't simply a cut and paste from some other site ?

When I used to manage a political forum on MSN, one of my pet hates was the 'cut and paste' brigade. People whose every post was not their own ideas or words, but simply cut from some news site or wherever.

Such people display that they DON'T really understand the issues, as they are not capable of debating an issue using their own knowledge but somehow seem to feel that they gain 'authority' by simply cutting and pasting someone else's words.

It is well nigh impossible to have any sort of intellectual debate with such a person.

 

[RainmanTime]

Khan,

Are you actually capable of a post that isn't simply a cut and paste from some other site ?
(snip)
It is well nigh impossible to have any sort of intellectual debate with such a person.

I agree with Twighlight. Several times now I have challenged some of the scientific (or not) thoughts behind your posts. Rather than engage me like a human being, you answered with quotes from some site. Those quotes, by the way, did not address the question/issue I put to you, although you may think they did in some twisted way.

The least you could do is directly speak to people, answering their questions/issues with your posts, before you cite a quote from somewhere. Because what you are doing is rude, and furthermore does not display to us that you have a level of intelligence high enough to debate some of this heady stuff.

Please and thanks,
RMT

 

[RainmanTime]

Khan,

Another point: Would you be willing to use the "quote" function so I know what you are responding to? For example:

http://www.dailygalaxy.com/my_weblog/2008/01/parallel-univer.html

quote:

"

Their research shows that Everett was indeed on the right track when he came up with his multiverse theory. The Oxford team, led by Dr David Deutsch, showed mathematically that the bush-like branching structure created by the universe splitting into parallel versions of itself can explain the probabilistic nature of quantum outcomes.

The work has another strange implication. The idea of parallel universes would apparently side-step one of the key complaints with time travel. Every since it was given serious credibility in 1949 by the great logician Kurt Godel, many eminent physicists have argued against time travel because it undermines ideas of cause and effect. An example would be the famous “grandfather paradox” where a time traveler goes back to kill his grandfather so that he is never born in the first place.

But if parallel worlds do exist, there is a way around these troublesome paradoxes. Deutsch argues that time travel shifts happen between different branches of reality. The mathematical breakthrough bolsters his claim that quantum theory does not forbid time travel. "It does sidestep it. You go into another universe," he said. But he admits that there will be a lot of work to do before we can manipulate space-time in a way that makes “hops” possible. While it may sound fanciful, Deutsch says that scientific research is continually making the theory more believable.

"Many sci-fi authors suggested time travel paradoxes would be solved by parallel universes but in my work, that conclusion is deduced from quantum theory itself."

The borderline between physics and metaphysics is not defined by whether an entity can be observed, but whether it is testable, insists Tegmark.

He points to phenomena such as black holes, curved space, the slowing of time at high speeds, even a round Earth, which were all once rejected as scientific heresy before being proven through experimentation, even though some remain beyond the grasp of observation. It is likely, Tegmark concludes that multiverse models grounded in modern physics will eventually be empirically testable, predictive and disprovable.

I have no idea what this quote (the bold part or the normal text part) is responding to. Could you please:

a) Quote the part of my posts (or anyone's post) that you are responding to.
b) Use some of your own words to set the context for your answer...and THEN...
c) Cite material from other sources (if you must).

Another note: Max Tegmark is a theoretician. A very intelligent one, but his opinions about how things might be are not facts, nor necessarily scientifically established. Unfortunately, this is how a lot of the newly minted PhD's seem to operate: They take a theoretical construct which has not been validated (such as David Deutsch's version of the multiverse) and build upon it with pretty graphics/concepts of their own (equally unvalidated) with pictures of Mandelbrot sets and cats in boxes floating in space.

RMT

 

[Packerbacker]

quote: The borderline between physics and metaphysics is not defined by whether an entity can be observed, but whether it is testable, insists Tegmark.

I don't get this. An entity which is metaphysical but observable? Like what?

He points to phenomena such as black holes, curved space, the slowing of time at high speeds, even a round Earth, which were all once rejected as scientific heresy before being proven through experimentation, even though some remain beyond the grasp of observation.

proven through experimentation....but....beyond the grasp of observation

Duh...?

It is likely, Tegmark concludes that multiverse models grounded in modern physics will eventually be empirically testable, predictive and disprovable.

[/quote] One certainly hopes so. :D

 

[RainmanTime]

quote: The borderline between physics and metaphysics is not defined by whether an entity can be observed, but whether it is testable, insists Tegmark.

I don't get this. An entity which is metaphysical but observable? Like what?

Yes, I agree, especially when one understands that to "test" means to "collect data" which means that one must "observe" something. Unless Tegmark is using the non-scientific meaning of "observe" which is limited to human visual spectrum (and if he is, shame on him!).

It is like I mentioned above about the newly minted generation of PhDs... the large majority of them could go their entire career without testable results for the things they ponder and try to develop theories about. The "publish or perish" paradigm has a strong hold on academia. Less important is testing one's theories. More important is getting lots of papers out there so later students can cite your work.

RMT

 

[khan2012]

If you are going to put all these restrictions and stipulations and how and what I post then I see no point in continuing. This forum is about TIME TRAVEL and time travel is currently highly theoretical and speculative.

Have fun being the thought police.

 

[RainmanTime]

If you are going to put all these restrictions and stipulations and how and what I post then I see no point in continuing.

Restrictions and stipulations? You actually mean it is too much to ask to have you actually participate in a normal conversation, rather than just be a quote-monkey? Honestly... what you are doing is downright rude to the readers attempting to engage you.

This forum is about TIME TRAVEL and time travel is currently highly theoretical and speculative.

And you are so lazy that you would rather just post other people's speculations, rather than burn calories of your own?

Have fun being the thought police.

Gee. Where did you get THAT quote from? 1984?
RMT

 

[Packerbacker]

If you are going to put all these restrictions and stipulations and how and what I post then I see no point in continuing.

And another one rides the bus. /ttiforum/images/graemlins/ooo.gif

 

[khan2012]

Leptons and hadrons could care less about grandfather and grandson. All they care about is that their numbers are conserved plus an assortment of other conserved quantities associated with them. And they are absolutely indistinguishible from one another. When and where they appear in some configuration space, alive or dead, the particles making up gramps and grandson will just continue on with their existence oblivious to the fact that someone somewhere perceived a paradoxical situation. Neither their existence nor an "observation" as defined in QM requires an intelligence to be present to resolve the interaction.

Applying a classical situation, the Grandfather Paradox, to a strictly quantum interaction, the state vectors of two or more individual sub-atomic particles, is mixing apples and oranges. Applying it to general relativity, a classical theory of physics, is appropriate.

The need for a solution TO the paradox applies to individual particles as well as larger configurations of particles called people.

Any action via traveling back in time or otherwise, that prevents the time travel in the first place, means that the time travel does not take place.

A reference:

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


quote:

"

Novikov self-consistency principle

See the Novikov self-consistency principle and Kip S. Thorne for one view on how backwards time travel could be possible without a danger of paradoxes. According to this hypothesis, the only possible timelines are those which are entirely self-consistent, so that anything a time traveler does in the past must have been part of history all along, and the time traveler can never do anything to prevent the trip back in time from being made since this would represent an inconsistency. In laymen's terms, this is often called destiny and it is sometimes unpopular because it contradicts the "common sense" notion that people choose their own fates.




Parallel universes/alternate timelines

There could be "an ensemble of parallel universes" such that when the traveller kills the grandfather, the act took place in (or resulted in the creation of) a parallel universe in which the traveller's counterpart will never be conceived as a result. However, his prior existence in the original universe is unaltered.

Examples of parallel universes postulated in physics are:

* In quantum mechanics, the many-worlds interpretation suggests that every seemingly random quantum event with a non-zero probability actually occurs in all possible ways in different "worlds", so that history is constantly branching into different alternatives. The physicist David Deutsch has argued that if backwards time travel is possible, it should result in the traveler ending up in a different branch of history than the one he departed from.[3] See also quantum suicide and immortality.

* M-theory is put forward as a hypothetical master theory that unifies the six superstring theories, although at present it is largely incomplete. One possible consequence of ideas drawn from M-theory is that multiple universes in the form of 3-dimensional membranes known as branes could exist side-by-side in a fourth large spatial dimension (which is distinct from the concept of time as a fourth dimension) - see Brane cosmology. However, there is currently no argument from physics that there would be one brane for each physically possible version of history as in the many-worlds interpretation, nor is there any argument that time travel would take one to a different brane.


"