Time Travel is Science Fiction

[Billy T]

...
Let's try and explain it this way.....
You are on earth....I'm sitting on the Sun.....
How do we synchronise our clocks?
You send me a message on the "mark"to synchronise my clock at 1200hrs...Good.
I receive that message 8.25 minutes later at 1208.25 hrs
Are you seeing the fault in your "analogy"yet?

Yes that is a foolish way to synchronize clocks that are 8.25 light seconds apart.

The cheapest way, since you know the separation is for one to send the "t is now" zero MARK to the other who sets his clock to 12:08:25 when the signal is received.

A more costly way is to have mirror at both sites and go what you hope is the midway point and test it with brief flash sent at same time towards each mirror. When reflected light form morrow "a" returns before than from mirror "b" by "delta t" seconds you move c(delta t)/2 farther form mirror "a" Then send more flashes and the msg: "These came form our mutual mid point."

BTW, one (or more) of the visits to the moon left "corner cube" mirrors on the moon. They have been used to confirm experimentally that the moon to Earth separation is in fact increasing. Tidal dissipation is why.

 

[Billy T]

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

If you read the portion of the profesor's statement in red, as in response to Billy's position, it must be assumed he is saying that both the future and the past have some physical existence, right now.., according to GR.., because Billy is saying they don't. That is an interpretation and opinion, on the part of the good professor! GR is a theory. As far as I know there is no experimental evidence supporting the idea that the past and future have any physical reality right now... While it is certain the the past did occur and that the future will occur and that GR does as a theory deal with past, present and future events.., the idea that the past and future have any physical existence right now in the present, is opinion... And there are scholars of GR on both sides of the argument.

Absolutely correct. To put it crudely the Professor's POV is crazy - only possible in a completely deterministic universe* - he is denying the existence of very well established quantum events. I. e. that atomic scale states can be superposition of two Eigen states and the "observation" can result in EITHER Eigen state. Every second that passes produced a new state of the universe and each of the trillion, trillion plus possible "new states" is different from all the others.

Again: You can not "travel to the future" as it does not yet exist anywhere. There are several ways you can slow your rate of aging. Most common one, which I use, is to exercise and eat a healthy diet. Eating a low calorie diet I don't do, but my "body weight index" is very good as I am tall and thin.

I have about a 25% change of living to be 100 years old, and the great news is that probability is INCREASING !

* Kiss your "free will" fantasy, good by.

 

[PhysBang]

Absolutely correct. To put it crudely the Professor's POV is crazy - only possible in a completely deterministic universe - he is denying the existence of very well established quantum events. I. e. that atomic scale states can be superposition of two Eigen states and the "observation" can result in EITHER Eigen state. Every second that passes produced a new state of he universe and each of the trillion, trillion plus possible "new states" is different from all the others.

Yet this is an interpretation of quantum mechanics, not the science. We can equally well interpret QM as a hidden variable theory, as long as we are willing to accept non-locality. And, certainly, we could accept a block universe model as instantiating a certain form of non-locality (i.e., the outcomes of the experiments were, in fact, determined before the experiment began and this inflenced the beginning of the experiment).

I don't belive in the block universe, myself, but there isn't much in the way of evidence regarding it.

 

[theorist-constant12345]

I don't believe you are being honest in the discussion.

The question is, Does time travel exist? Not what is time?

While how you answer the second does influence any discussion of the first, by beginning with that first question the second has been already set aside. Not necessarily agreed upon but assumed to exist. That is.., the question, Does time travel exist?, already assumes that time exists. Your statement that, "it is not time that dilates, it is a change of timing..." Is a question about time itself not time travel.

Your argument is the same as saying, I don't believe in time travel, because I don't believe in time!

There is another thread for the underlying apparent intent of your comment.

The whole point being, that you can not travel through a thing that is not a real thing. The misconception of time itself, being the cause of what causes gibberish theory, such has ''time travel''. You do not travel forward in time, you cannot travel back in time.
However, this is based on the counting of our time, and not to say an alternative reality, a different domain of space time, is not evolved differently to our time.

Imagine a mirrored visual universe to our own, but 2014 years less evolved than our own. We would see ourselves of the past if we could travel there.
If a there existed of cause.

And the reality is, this is the only sort of ''time travel'', that could possibly exist.

 

[OnlyMe]

Absolutely correct. To put it crudely the Professor's POV is crazy - only possible in a completely deterministic universe* - he is denying the existence of very well established quantum events. I. e. that atomic scale states can be superposition of two Eigen states and the "observation" can result in EITHER Eigen state. Every second that passes produced a new state of the universe and each of the trillion, trillion plus possible "new states" is different from all the others.

Again: You can not "travel to the future" as it does not yet exist anywhere. There are several ways you can slow your rate of aging. Most common one, which I use, is to exercise and eat a healthy diet. Eating a low calorie diet I don't do, but my "body weight index" is very good as I am tall and thin.

I have about a 25% change of living to be 100 years old, and the great news is that probability is INCREASING !

* Kiss your "free will" fantasy, good by.

I have to believe that the Professor's comments were based on an incomplete transcript of the discussion. GR does deal with past, present and furture events... I just don't see it proclaiming any present physical reality to anything but the present.

 

[OnlyMe]

The whole point being, that you can not travel through a thing that is not a real thing. The misconception of time itself, being the cause of what causes gibberish theory, such has ''time travel''. You do not travel forward in time, you cannot travel back in time.
However, this is based on the counting of our time, and not to say an alternative reality, a different domain of space time, is not evolved differently to our time.

Imagine a mirrored visual universe to our own, but 2014 years less evolved than our own. We would see ourselves of the past if we could travel there.
If a there existed of cause.

And the reality is, this is the only sort of ''time travel'', that could possibly exist.

Your argument does not belong in this discussion. As I said there is a thread, What is Time. The question here assumes that time does exist. Thus your arguments are not relevant to the question here!

 

[PhysBang]

I have to believe that the Professor's comments were based on an incomplete transcript of the discussion. GR does deal with past, present and furture events... I just don't see it proclaiming any present physical reality to anything but the present.

If we accept that the Godel solutions are a legitimate solution to GR, then it seems that we have to accept that events can be both the past and future of other events (and themselves). Now, given the many time related phenomena in physics that seem to indicate a direction, it may be that there are other reasons to deny the Godel solutions that lie outside of GR. Few, if any, people believe that GR is complete, so this isn't a problem for GR, just an interesting fact.

 

[OnlyMe]

If we accept that the Godel solutions are a legitimate solution to GR, then it seems that we have to accept that events can be both the past and future of other events (and themselves).

Emphasis on the if in blue and there is no question as to the validity of the statement in standard bold. .... (and themselves) could apply in as far as seeing yourself in a mirror might affect your present, but that does not make the past represented in the mirror, anymore real now than the light from a star makes what we see a description of the star now.

No issues with the following.

Now, given the many time related phenomena in physics that seem to indicate a direction, it may be that there are other reasons to deny the Godel solutions that lie outside of GR. Few, if any, people believe that GR is complete, so this isn't a problem for GR, just an interesting fact.

 

[PhysBang]

Emphasis on the if in blue and there is no question as to the validity of the statement in standard bold. .... (and themselves) could apply in as far as seeing yourself in a mirror might affect your present, but that does not make the past represented in the mirror, anymore real now than the light from a star makes what we see a description of the star now.

Yet the Godel solutions I am thinking of are significantly different in that there exist closed timelike loops. This is more than simply a reflection from one event reaching another event where we identify the same object, this is a line of cause and effect leading from one event to that same event.

 

[paddoboy]

Yes that is a foolish way to synchronize clocks that are 8.25 light seconds apart.

The cheapest way, since you know the separation is for one to send the "t is now" zero MARK to the other who sets his clock to 12:08:25 when the signal is received.

You are still ignoring different tick rates.....

BTW, one (or more) of the visits to the moon left "corner cube" mirrors on the moon. They have been used to confirm experimentally that the moon to Earth separation is in fact increasing. Tidal dissipation is why.

Plus the rotational velocity of the Earth is slowing due to tidal friction and both will continue until an Earth day is equal to a lunar month, in around 2 to 3 billion years?
Not sure what it has to do with the fact that we do not have a universal now.

 

[OnlyMe]

Yet the Godel solutions I am thinking of are significantly different in that there exist closed timelike loops. This is more than simply a reflection from one event reaching another event where we identify the same object, this is a line of cause and effect leading from one event to that same event.

By emphasizing the IF in, "If we accept the Godel solutions...", I was saying I don't.

I followed that by agreeing that events (now) can be both the past and future of other events. Something led to now and now leads to something else... I did not mean to confuse the mirror analogy that followed with Godel's solutions.

Separating the, (and theirselves) was excluding it from association with the statement above and then qualifying that.., as I did.

I should have separated the comment into better defined and separate comments.

All of this is what I believe, because obviously I cannot know.

 

[paddoboy]

Absolutely correct. To put it crudely the Professor's POV is crazy....

It's the same view held by Carroll, Smolin, Kaku, and Sagan, as well as most Astrophysicists today.

Again: You can not "travel to the future" as it does not yet exist anywhere.

Again, time travel is not forbidden by the laws of physics and GR, and possibilities are evident in how this could be achieved through the equations of GR.

There are several ways you can slow your rate of aging. Most common one, which I use, is to exercise and eat a healthy diet. Eating a low calorie diet I don't do, but my "body weight index" is very good as I am tall and thin.

Rubbish! You are now grasping at straws...Time is still progressing and your body is aging in line with that.
I'm short and nuggety, but what has this to do with time travel and its possibilities?

 

[quantum_wave]

You are still ignoring different tick rates.....

...

Not sure what it has to do with the fact that we do not have a universal now.

A question for you paddoboy, regarding the now in your frame. Given two inertial frames, wouldn't the Lorentz transformations allow you to determine what the time would be on your clock if it somehow materialized in the other frame?

 

[tashja]

Prof. Alcubierre's response is obviously an opinion, rather than a fact.

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

If you read the portion of the profesor's statement in red, as in response to Billy's position, it must be assumed he is saying that both the future and the past have some physical existence, right now.., according to GR.., because Billy is saying they don't. That is an interpretation and opinion, on the part of the good professor! GR is a theory. As far as I know there is no experimental evidence supporting the idea that the past and future have any physical reality right now... While it is certain the the past did occur and that the future will occur and that GR does as a theory deal with past, present and future events.., the idea that the past and future have any physical existence right now in the present, is opinion... And there are scholars of GR on both sides of the argument.

Absolutely correct. To put it crudely the Professor's POV is crazy - only possible in a completely deterministic universe* - he is denying the existence of very well established quantum events. I. e. that atomic scale states can be superposition of two Eigen states and the "observation" can result in EITHER Eigen state. Every second that passes produced a new state of the universe and each of the trillion, trillion plus possible "new states" is different from all the others.

Again: You can not "travel to the future" as it does not yet exist anywhere. There are several ways you can slow your rate of aging. Most common one, which I use, is to exercise and eat a healthy diet. Eating a low calorie diet I don't do, but my "body weight index" is very good as I am tall and thin.

I have about a 25% change of living to be 100 years old, and the great news is that probability is INCREASING !

* Kiss your "free will" fantasy, good by.

Prof. Alcubierre:

It is not an opinion, simultaneity is relative, and we have known this for over 100 years. This means that there is simply no way to even define "the present" except a a single point. Asking what is happening in Andromeda "right now" doesn't even make physical sense, so past and future coexist. This is not only what GR says, it is also what special relativity says.

Yes, GR and SR are theories, the very best we have. They have not failed a single time experimentally or observationally. We live in a 4-dimensional space-time, not in a 3-dimensional space plus time. This is very well understood.

Why we "feel" time happening in just one direction is indeed an open question. Time travel to the future due to time dilation is perfectly possible. Time travel to the past could be consistent with GR (through a worm-hole for example) as long as nothing is altered. That is, if you could travel to the past then it is already part of history, nothing changed. Everything would have to be consistent. No paradoxes are allowed. This is what GR says. Since this sounds difficult to accept because it would clearly limit free will, then the obvious solution is that you can't travel to the past. Maybe it is impossible to create a worm-hole, even if they would in principle be allowed by GR.

Miguel Alcubierre

 

[PhysBang]

By emphasizing the IF in, "If we accept the Godel solutions...", I was saying I don't.

You don't accept that the Godel solutions are mathematical solution to the Einstein field equation? That's a fairly radical position.

 

[OnlyMe]

You don't accept that the Godel solutions are mathematical solution to the Einstein field equation? That's a fairly radical position.

I did not say that. What I meant to be saying is that I don't believe they represent reality.

 

[Billy T]

Yet this is an interpretation of quantum mechanics, not the science. We can equally well interpret QM as a hidden variable theory, as long as we are willing to accept non-locality. ...

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.

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.

 

[paddoboy]

tashja...thanks again, and could you please pass on my total agreement with the good professor and his following statement.......

Prof. Alcubierre:

It is not an opinion, simultaneity is relative, and we have known this for over 100 years. This means that there is simply no way to even define "the present" except a a single point. Asking what is happening in Andromeda "right now" doesn't even make physical sense, so past and future coexist. This is not only what GR says, it is also what special relativity says.

Yes, GR and SR are theories, the very best we have. They have not failed a single time experimentally or observationally. We live in a 4-dimensional space-time, not in a 3-dimensional space plus time. This is very well understood.

Why we "feel" time happening in just one direction is indeed an open question. Time travel to the future due to time dilation is perfectly possible. Time travel to the past could be consistent with GR (through a worm-hole for example) as long as nothing is altered. That is, if you could travel to the past then it is already part of history, nothing changed. Everything would have to be consistent. No paradoxes are allowed. This is what GR says. Since this sounds difficult to accept because it would clearly limit free will, then the obvious solution is that you can't travel to the past. Maybe it is impossible to create a worm-hole, even if they would in principle be allowed by GR.

 

[Billy T]

... Time travel to the future due to time dilation is perfectly possible. ... This is what GR says. Since this sounds difficult to accept because it would clearly limit free will, then the obvious solution is that you can't travel to the past. ...[/B]

And travel into a future now existing (already fully determined) is a total and complete DESTRUCTION of the concept of free will.

Again: what you can do by at least 4 different ways to experience a more distant future as your "now" is slow your rate of aging so you are still alive when it becomes (briefly) your now. You can call, I think very deceptively, slowing your rate of aging "time travel." That phrase has an entirely diffent meaning in 10,000 science fiction stories. Again: Is English your native language?

 

[paddoboy]

And travel into a future now existing (already fully determined) is a total and complete DESTRUCTION of the concept of free will.

I did not say that Billy...I was quoting the good professor. And of course there are many solutions around such paradoxes. I'm sure the good professor knows and realises that.