Time Travel is Science Fiction

OnlyMe said:
Prof. Alcubierre: What "Billy" says is not correct. According to General Relativity, the future and past do exist.
Click to expand...
I think language and grammar themselves help us out here. "do exist" is the present tense; i.e., they exist now. The future exists now in that it can be spoken about and thought of, but that is the extent of it because how do we know the universe won't come crashing down around our ears at any moment? I know it is unlikely, but... As for the past existing in the present, of course it does. The Great Pyramid at Giza would be an excellent example. It surely existed in the past, and has survived into the present, and will probably still be here next week, but when next week comes that will be the present, not the future or the past. So future and past only exist in the present, which is the only time worth considering, they themselves are mere thought configurations.
 
Billy T said:
Totally irrelevant. What causes the result of an observation on a QM system is not the issue. It could be "hidden variables" as Einstein believe when he said "God does not roll dice." but later accepted the commn POV.
Click to expand...
It is only irrelevant if one believes that one can directly observe chance rather than infer it with the help of some assumptions.

Point is that you can not predict the future if anyone has free will. Either that being true or the nearly total acceptance that mixed Eigen state system are real being correct, means that with each passing second nature (and man if you believe he has free will) CHOOSES ONE of more than a trillion, trillion (all different) new states for the universe. Ergo there is not one now one existing "future" that will arrive as the "now" only one second from now.
Click to expand...
Unsurprisingly, you are simply begging the question in favor of your position.

If we live in a deterministic block universe, it doesn't matter what "choice" is made by someone, it is something that is part of the standard physical set of events obeying the laws of physics. So the "random" events of QM are determined in part by the eventual measurements that were going to be run on them.
 
OnlyMe said:
I did not say that. What I meant to be saying is that I don't believe they represent reality.
Click to expand...
They surely don't.

So there are two options.

a) They don't represent reality simply because of the arrangement of matter and energy in the world but it could, in principle, happen.

b) They don't represent reality because of another physical principle outside of GR.
 
Billy T said:
My virus protection blocked opening Paddoboy's first link in post 1119, but this is a quote from the second:
Click to expand...

Not sure why.....
let me help.....it is lengthy...at least too lengthy for me to paste.
it starts....
Do the laws of nature allow for time travel? We won’t answer this question, because the answer depends on what the laws of nature really are, and that is a matter we leave to the scientists, and specifically the physicists. Still, what we do have to say here is certainly pertinent to the question. Take this as an elementary primer for a study of the actual physics of time travel.

Our modest goal is to sketch how both forward and backward time travel are permitted by relativity theory. The prospects of forward time travel are less complex to describe and will require fewer idealizations. Backwards time travel is much more a matter of purely theoretical consideration. After a brief introduction to relativity theory, we will describe a case of time travel to the future and a case of time travel to the past; each case is consistent with the laws of relativity theory.

It concludes:
That is our introductory case for the conclusion that forward time travel and backward time travel are consistent with the theory of relativity. In fact, we have described two different methods for traveling to the future: (i) traveling along a different (shorter) path through spacetime than the rest of your civilization, or (ii) hopping in the earlier end of a wormhole time machine that connects two points in the history of your civilization. The wormhole time machine provides our only case of time travel to the past: Tim’s hopping in the later mouth of the wormhole connecting events in the history of his civilization. There are other possibilities permitted by relativity theory that provide for time travel to the future and time travel to the past. In Time Travel in Einstein’s Universe(Chapters 2 and 3), J. Richard Gott nicely describes some of these methods including a stay-at-home method of traveling to the future, a wormhole time machine, and Gott’s own two-cosmic-strings method for traveling to the past.

For those of you looking for a conclusive statement on whether the actual laws of nature permit time travel to the past, you’ll need to wait for a theory that goes beyond relativity theory, something like a finalized theory of quantum gravity. Thorne has recently provided an accessible sketch of his and other physicists’ doubts about whether the actual laws of nature do permit time travel in “Is Time Travel Allowed?” For those of you who are adventurous and feel ready to deal with some difficult physics, Smeenk and Wϋthrich’s “Time Travel and Time Machines” (2011) includes advanced discussion of whether time travel is permitted by our laws.
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::

He also references the same excellent Kip Thorne link I have provided at least 8 times?



Billy T said:
"The properties of quantum particles are 'fuzzy' or uncertain to start with, so this gives them enough wiggle room to avoid inconsistent time travel situations," he said."

Clearly marked as an opinion by the "he said"
Click to expand...


We are all expressing opinions except for the one fact that GR does not forbid time travel, and in fact its equations show us the methodolgy.

I'm sticking with GR and the general consensus of opinion in mainstream science.
 
Landau Roof said:
I think language and grammar themselves help us out here. "do exist" is the present tense; i.e., they exist now. The future exists now in that it can be spoken about and thought of, but that is the extent of it because how do we know the universe won't come crashing down around our ears at any moment? I know it is unlikely, but... As for the past existing in the present, of course it does. The Great Pyramid at Giza would be an excellent example. It surely existed in the past, and has survived into the present, and will probably still be here next week, but when next week comes that will be the present, not the future or the past. So future and past only exist in the present, which is the only time worth considering, they themselves are mere thought configurations.
Click to expand...

I don't believe you can break it down to the language of one sentence. The second was a conditional response to the first.

"Prof. Alcubierre: What "Billy" says is not correct. According to General Relativity, the future and past do exist."

Since Billy's argument was that the past and future have no physical reality now, the Professor's comment has to be interpreted as saying that they both do!

The bigger issue in this whole discussion, is the one I raised about the definition of time-travel itself. Go through the posts. There is no single definition that fits. Sometimes not even from beginning to end of a single post.

Why? Because as the thread title suggests, time-travel is science fiction.
 
paddoboy said:
...We are all expressing opinions except for the one fact that GR does not forbid time travel, and in fact its equations show us the methodolgy.
Click to expand...
Two points:
(1) I was willing to agree that that the laws of physics do not prohibit many , many things that I symbolically called X, one of which was the X = Time Travel* but I read the link at the end of you post 1124 of the link my virus protection would not let me open. Thanks for that partial quote of it. Here is what I read:
http://plus.maths.org/content/time-travel-allowed said:
... When we physicists have mastered the laws of quantum gravity (Hawking and I agree), we will very likely discover that chronology is protected: the explosion always does destroy any time machine, when it is first activated.
Click to expand...
(2) Hawking & Thorn are quite smart "cookies" so Now I have strong doubts that your: the laws of physics do not prohibit time travel* is even true. They seem to say those laws do prohibit it by "time travel macines, at least but not by any of the methods that slow your rate of aging (as measured by clocks of Earth).

But be that as it may be, it is unimportant as: "Not prohibited" is not the same as "Is possible."

* Time travel as you understand it being more than just slower than normal aging and requiring technlogy of a more advanced civilization, than even just suspended animation.
 
Last edited by a moderator:
OnlyMe said:
Why? Because as the thread title suggests, time-travel is science fiction
Click to expand...
At least we can all agree on that. Yes, I see what you mean; the past has some physical reality now, as in the case of the Great Pyramid or a thing that was here five minutes ago and still remains.
 
Last edited:
OnlyMe said:
... Since Billy's argument was that the past and future have no physical reality now, the Professor's comment has to be interpreted as saying that they both do! ...
Click to expand...
That is correct and worse he is denying both free will and the probabilistic nature of QM results as his "now existing future" must be evolved from the present by purely deterministic laws of physic. His POV that the future, very nano second of it, already exist also does away with the concept of sin and responsibility - the child murder had to kill the child as that child is not alive in the already existing future of the professor.
 
Last edited by a moderator:
Billy T said:
That is correct and worse he is denying both free will and the probabilistic nature of QM results as his "now existing future" must be evolved from the present by purely deterministic laws of physic.
Click to expand...
No he isn't.
 
Billy T said:
Two points:
(1) I was willing to agree that that the laws of physics do not prohibit many , many things that I symbolically called X, one of which was the X = Time Travel* but I read the link at the end of you post 1124 of the link my virus protection would not let me open. Thanks for that partial quote of it.
Click to expand...

I believe you are reading what you want into it...confirmation bias if you will......and it was the whole quote...the rest was the different methodology of how it could be achieved




Billy T said:
Here is what I read: (2) Hawking & Thorn are quite smart "cookies" so Now I have strong doubts that your: the laws of physics do not prohibit time travel* is even true. they seem to say those laws do prohibit it.
Click to expand...

Like I said, you are reading what you want into it...
Here is the site he referenced...
http://plus.maths.org/content/time-travel-allowed
Here's a couple more for good measure....
http://www.pbs.org/wgbh/nova/physics/Sagan-Time-Travel.html
http://mkaku.org/home/articles/the-physics-of-time-travel/
That's just off the top of my head...many more I have already given.


Billy T said:
But be that as it may be, it is unimportant as: "Not prohibited" is not the same as "Is possible."
Click to expand...

You keep saying that. Why? Putting words into my mouth again?
Just to refresh your memory and to highlight what you seem emotionally unable to accept, is that time travel is not forbidden by GR and the laws of physics.
I'll put a couple of words in your mouth now, "not prohibited" is not the same as "Impossible" alrighty?
 
Billy T said:
That is correct and worse he is denying both free will and the probabilistic nature of QM results as his "now existing future" must be evolved from the present by purely deterministic laws of physic. His POV that the future, very nano second of it, already exist also does away with the concept of sin and responsibility - the child murder had to kill the child as that child is not alive in the already existing future of the professor.
Click to expand...

I think in a way my comments are too critical of the professor. If you read I think his last response from beginning to end he was presenting a spectrum of context, which could not easily fit a single definition of time travel. And he did end with a theoretical context.

I think my earlier comment was better, and he was just unaware of the breadth of the discussion. Didn't know he might be stepping into quicksand so to speak.
 
I am not so well versed in science as OM and BT, but surely Billy is right. Only think. How can the future be a predetermined and set and decided thing? I, for a humble instance, may decide not to take the main street bus home tonight, but opt at the last moment to walk to the next parallel street to get an alternate bus there, and my small action might result in a whole different set of future events that reach far beyond me in ways we cannot guess. Therefore time-travel into the future is of course utterly impossible because what branch of the multitudinous possibilities of the so called future would you travel to? Every little happening that happens opens up new possibilities. If you travel to the future do you travel to the one, say where an asteroid the size of Connecticut didn't smash into Berlin on August 1oth 2341 and cause a great extinction and the end of civilization as we know it? Or one in which indeed it has? None of the future has happened yet, so how can we 'direct the controls of a time machine' to a certain time or place. As I said, in effect, in an earlier post, you could travel to your own time laboratory/backyard shed 500 years hence and find yourself under 1,000 feet of water or 50 feet up in the air, or in the middle of a concrete beam. How will you know until you get there?
 
Last edited:
Landau Roof said:
I am not so well versed in science as OM and BT, but surely Billy is right.
Click to expand...

Billy has an opinion...I have an opinion.
Irrespective, time travel is not forbidden.
The non absolute nature of space and time originally was also counter-intuitive at one time...BH's were counter-intuitive also...DM in recent times was also counter-intuitive. :shrug:
What you find as counter-intuitive is nether here nor there when you are confronted by experimental and observational data that says different.
 
quantum_wave said:
"8. What actually happens when a disk is put into rotation depends upon its elastic properties. A maximally rigid disk, with sound velocity equal to the velocity of light, will in fact contract when its angular velocity is increased.
Click to expand...

Gron's paper was a consolation of all the different approaches and attempts at solutions over the years. This problem was sidestepped and wasn't part of Gron's solution as the wheel was considered as having no thickness (through the z axis being zero) as points 3 and 4 of his conclusions reveal.
3. Due to the relativity of simultaneity Born rigid rotating motion of a ring with angular
acceleration represents contradictory boundary conditions.
4. If the disk is regarded as a 2-dimensional surface it can be put into rotation in a Born
rigid way, that is without any displacements in the tangential plane of the disk, by
bending for example upwards so that it obtains the shape of a cup.
Click to expand...

In the cases of ships traveling in a circle or even rotating sources (galaxies) the principles are the same but the Born rigidity does not actually come into it as it is not a solid wheel as such. This is why SR works because mass and rigidity are not considered and only the positions where the light was emitted and where the light is received are important to the solution (at least for rotating ships and sources).
 
Just a heads up - Paddoboy, I updated your post (1136) at tashja's request - the professor in question asked to remain nameless
 
paddoboy said:
The non absolute nature of space and time originally was also counter-intuitive at one time...BH's were counter-intuitive also...DM in recent times was also counter-intuitive. :shrug:
Click to expand...

The differences between SR and GR and how each regards time travel are a bit counter intuitive as well until you look at other components like the Compton wavelength and the Planck constant, their reduced forms and the roles they play in the SR and GR equations.

Paddoboy, if you have any links to new DM papers that show the latest figures it would be much appreciated.

I have not seen any lately and wonder how the recent news that nearly half of the stars we see would not be considered to be part of any galaxy would impact on calculations. Out of all the papers I have read about DM there is only one which is a rebuttal of a no DM paper and the difference between DM and no DM seemed to rest on which radius you used in calculations for the mass of non central disk stars (center of mass for no DM or axis of rotation for DM).

The DM clouds are only found outside galactic disks so the results from current calculations to date would include many stars (up to 50 %) that would not actually be part of any galaxy. It seems reasonably evident that galaxy rotation curves and mass calculations need to be urgently adjusted to reflect this major change.

If there is nowhere near as much DM as we thought or if it doesn't exist then I would agree that we have taken a great step into the future (without traveling through time).
 
You must log in or register to reply here.
Back
Top