Time Traveling - Impossible?

[DrRocket]

Time travel means we can go back to the past or go forward into the future or both.

 

Of course we can.

 

I just traveled about 30 seconds in the future direction while typing this.

 

DrRocket, as always you use "spacetime" as a given matter of established fact. I'm guessing you didn't read any of the material I suggested on the ontology of it. Fine, but that doesn't make its critics wrong just because you refuse to even engage in the conversation on the subject.

 

Yeah, I took a look at it. It simply showed me that, in addition to not understanding general relativity, you don't understand your own references. For instance, while you assume, using a wild trail of illogic, that the universe must be infinite, it is listed as an open question by your vaunted ISASS.

 

The only point in even addressing your posts is to mitigate the damage that might occur to people who are actually trying to learn a bit about relativity.

[owl]

DrRocket:

Of course we can.

 

I just traveled about 30 seconds in the future direction while typing this.

But seriously!... How did you get out of the ongoing present? Could you see what you typed in real time (not just in imagination) before you typed it, from actually "traveling" 30 seconds into the furure? Can you jump to the end of a horse race before it starts and bet on the winner? Either you don't have a clue what the thread is asking or you don't take the question seriously.

 

Yeah, I took a look at it. It simply showed me that, in addition to not understanding general relativity, you don't understand your own references. For instance, while you assume, using a wild trail of illogic, that the universe must be infinite, it is listed as an open question by your vaunted ISASS.

I didn't say I agreed with everything published by Deiks or the ISASS, just that they are examining what spacetime actually is, rather than, with GR, simply taking it for granted as an established fact, like you do.

(BTW, how does quantum gravity theory fit in with your absolute certainty that "curved spacetime," as per GR, is the only valid explanation of how gravity works?)

I answered the rest of your post in the Is Space Infinite thread.

Edited May 17, 2011 by owl

[DrRocket]

DrRocket:

 

...(BTW, how does quantum gravity theory fit in with your absolute certainty that "curved spacetime," as per GR, is the only valid explanation of how gravity works?)

 

You, as usual, argue against a straw man. I have never said that curved spacetime is the only possible explanation of gravitation.

 

It is the only currently available model that explains the body of empirical data. That is simply a fact.

 

There are actually two models that match the data. They are general relativity and Einstein-Cartan theory. Both involve spacetime curvature. EC theory dispenses with the assumption that spacetime is torsion-free and is more difficult from a mathematical perspective. The two theories make predictions under most circumstances that are nearly the same and current technology does not permit experiments able to distinguish between the two.

 

You might extend the list of contenders to Beckenstein's modification of GR to handle MOND ideas regarding the "dark matter" issue, but you still have curved spacetime.

 

As to quantum gravity -- there is no current viable theory of quantum gravity. If and when it exists we will see. But any viable theory of gravitation, quantum or otherwise, will have to agree with the predictions of general relativity in most circumstances -- away from the center of a black hole and later than about 10^-33 sec after the big bang.

 

What never ceases to amaze is your absolute confidence in assertions that you make that are factually and demonstrably just plain wrong. How can you discuss the ontology of a theory about which you have no clue ?

[owl]

DrRocket, You have completely ducked the time travel question, the focus of this thread and specifically my last post... see key words "horse race."

 

Theories of gravity are not the subject here. (Apologies to the OP.) I just thought that quantum theory was a viable alternative to GR theory vis-a-vis gravity, which might belie your certainty.

Still, observed curvature of objects' paths of travel does not prove that spacetime is an entity which "curves" and guides objects.... Just to be clear about what the ontology addresses, whether you are interested or not.

[DrRocket]

DrRocket, You have completely ducked the time travel question, the focus of this thread and specifically my last post... see key words "horse race."

 

 

The answer lies not in philosophy and certainly not in ontology. It is a question of physics and a deep question at that. This issue has been recently discussed in the context of real physics -- much remains unknown.

 

http://www.scienceforums.net/topic/55142-does-einsteins-theory-of-relativity-support-time-travel/

[owl]

DrRocket:

The answer lies not in philosophy and certainly not in ontology. It is a question of physics and a deep question at that.

 

Really!? It would seem that a deep understanding of what time is and is not (ontology) would be quite relevant to the question, "Can we travel through it?" Anyway you continue to dodge the horse race question; and visiting the past is just as absurd, or we could "go back in time" and visit with our dead ancestors before they died, which would in many cases be before we were born!?

This is science? No, clearly just sci-fi.

[DrRocket]

DrRocket:

 

 

Really!? It would seem that a deep understanding of what time is and is not (ontology) would be quite relevant to the question, "Can we travel through it?" Anyway you continue to dodge the horse race question; and visiting the past is just as absurd, or we could "go back in time" and visit with our dead ancestors before they died, which would in many cases be before we were born!?

This is science? No, clearly just sci-fi.

 

Had you read, and understood, the thread to which I provided a link, you would know that your "horse race" question was not ducked. You need to learn some physics.

 

The heart of the matter is Stephen Hawking's "chronology protection conjecture".

 

It can be proved under some reasonable, but not universally accepted assumptions. It may not be true at the quantum level. It remains a conjecture.

 

Ontology has not contributed any understanding of the problem. Ontologists have contributed less.

 

“…How can we understand the world in which we find ourselves ? How does the universe behave ? What is the nature of reality ? Where did this come from ? Did the universe need a creator ? Most of us do not spend most of our time worrying about these questions, but almost all of us worry about them some of the time.

 

Traditionally these are questions for philosophers, but philosophy is dead. Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge.” -- Stephen Hawking in The Grand Design

 

 

[owl]

DrRocket:

Had you read, and understood, the thread to which I provided a link, you would know that your "horse race" question was not ducked. You need to learn some physics.

 

I will read the link and get back to you on it. (Patience can be helpful among busy people, even us crappy stupid pigeons.)

What I "need" is for me to decide, not you. You could benefit from (no need projected) a study of what ontology is for science rather than your constant bitter prejudice against all philosophy.

 

DrR:

The heart of the matter is Stephen Hawking's "chronology protection conjecture".

 

It can be proved under some reasonable, but not universally accepted assumptions. It may not be true at the quantum level. It remains a conjecture.

 

The "heart of the matter" for the scientific community as a whole is not Hawking's theories, in any case, though you obviously elevate him to near infallibility (with proper disclaimers, of course.)

 

Dr.R quoting Hawking:

…How can we understand the world in which we find ourselves ? How does the universe behave ? What is the nature of reality ? Where did this come from ? Did the universe need a creator ? Most of us do not spend most of our time worrying about these questions, but almost all of us worry about them some of the time.

 

These questions are often the focus of philosophy, but not exhaustive. For instance there are the more contemporary questions in the specific realm of philosophy of science, like the 'not dead yet' question, "What is spacetime?; Is it or not an entity or malleable medium in the real world?"

 

Doctor Rocket vehemently wants this question (and me with it!) to go away, but it won't, as lots of not-so-stupid philosophers and scientists are still working on the question... often together in mutual respect. Imagine that!

 

And what a premature pronouncement of death for philosophy followed by zealous evangelism for his version of scientists as saviors of the world!

Hawking:

Traditionally these are questions for philosophers, but philosophy is dead. Philosophy has not kept up with modern developments in science, particularly physics. Scientists have become the bearers of the torch of discovery in our quest for knowledge.” -- Stephen Hawking in The Grand Design

 

I have studied several mainstream scientists over the years (no citations on the tip of my tongue) who think very much less of him as a scientist than you do,DrR, and I am among them, at least as an amateur scientist (one who "loves it", but not a pro.)

 

Here is my best example of his non-scientific, even grandiose hyperbole. (I am in fact a retired psychologist who has seen lots of grandiosity, both "on the couch" and in such "celebrities" as Hawking):

 

His cosmology of a primordial singularity as the origin of the universe is the most absurd statement ever to be uttered by a scientist, in my personal opinion... that all cosmic matter came from a singularity of "infinite mass density in a point of zero volume." (Look at his site for conformation... maybe deleted by now, however, but surely still on record.)

 

Yet DrR has the highest regard for this pop fame (formally, popular and famous) scientists, and, I presume, his M-Theory buddies, now that they are all in the same camp. (The modern metaphysicians of physics.)

DrR:

Ontology has not contributed any understanding of the problem. Ontologists have contributed less.

 

That would be ontology as you understand it, which is minimal or not at all, as per your interest in it.

Edited May 20, 2011 by owl

[DrRocket]

DrRocket:

 

 

I will read the link and get back to you on it. (Patience can be helpful among busy people, even us crappy stupid pigeons.)

What I "need" is for me to decide, not you. You could benefit from (no need projected) a study of what ontology is for science rather than your constant bitter prejudice against all philosophy.

 

DrR:

 

 

The "heart of the matter" for the scientific community as a whole is not Hawking's theories, in any case, though you obviously elevate him to near infallibility (with proper disclaimers, of course.)

 

Dr.R quoting Hawking:

 

 

These questions are often the focus of philosophy, but not exhaustive. For instance there are the more contemporary questions in the specific realm of philosophy of science, like the 'not dead yet' question, "What is spacetime?; Is it or not an entity or malleable medium in the real world?"

 

Doctor Rocket vehemently wants this question (and me with it!) to go away, but it won't, as lots of not-so-stupid philosophers and scientists are still working on the question... often together in mutual respect. Imagine that!

 

And what a premature pronouncement of death for philosophy followed by zealous evangelism for his version of scientists as saviors of the world!

Hawking:

 

 

I have studied several mainstream scientists over the years (no citations on the tip of my tongue) who think very much less of him as a scientist than you do,DrR, and I am among them, at least as an amateur scientist (one who "loves it", but not a pro.)

 

Here is my best example of his non-scientific, even grandiose hyperbole. (I am in fact a retired psychologist who has seen lots of grandiosity, both "on the couch" and in such "celebrities" as Hawking):

 

His cosmology of a primordial singularity as the origin of the universe is the most absurd statement ever to be uttered by a scientist, in my personal opinion... that all cosmic matter came from a singularity of "infinite mass density in a point of zero volume." (Look at his site for conformation... maybe deleted by now, however, but surely still on record.)

 

Yet DrR has the highest regard for this pop fame (formally, popular and famous) scientists, and, I presume, his M-Theory buddies, now that they are all in the same camp. (The modern metaphysicians of physics.)

DrR:

 

 

That would be ontology as you understand it, which is minimal or not at all, as per your interest in it.

 

 

 

I will thank you to cease and desist from mis-stating and mis-representing my opinion of Stephen Hawking or anyone else. That extends to my opinion regarding any currently speculative physical theories. You may be a retired psychologist, but I am quite confident that you are no more clairvoyant than anyone else.

 

You may take whatever issue you feel capable of supporting with a concrete issue, but setting up a straw man by misrepresenting my opinions, which you very clearly do not grasp, is logically fallacious.

 

What is truly an exaggeration is your opinion of the gravitas of your opinion. You would do well to first understand a theory before you criticize it.

Edited May 20, 2011 by DrRocket

[steevey]

All this time travel stuff seems a bit convoluted. I would just not worry about it, especially since it would probably cause trouble if we did manage to do it.

Edited May 20, 2011 by steevey

[Ramesh ss]

My Future is undecided. Then how can I travel through something which has not been made yet.

[owl]

DrR:

I will thank you to cease and desist from mis-stating and mis-representing my opinion of Stephen Hawking or anyone else. That extends to my opinion regarding any currently speculative physical theories.

...

 

The heart of the matter is Stephen Hawking's "chronology protection conjecture".

 

So Hawking's conjecture is the "heart of the matter" of the time travel question, but I have misrepresented your opinion of him in this context? How so?

 

Quoting the intro to that conjecture:

“It has been suggested that an advanced civilization might have the technology to warp spacetime so that closed timelike curves would appear, allowing travel into the past.”

 

Oh!... All we need is "the technology to warp spacetime so that closed timelike curves would appear, allowing travel into the past." Now I get it!

How exciting! Then I could go back and talk to Plato himself about “platonic ideals.”... I mean, you know, if Hawking thinks it’s possible, who am I to question?!

DrR:

Had you read, and understood, the thread to which I provided a link, you would know that your "horse race" question was not ducked.

 

Just finished it. What was the answer to the horse race question? I didn't find it in the thread.

First, this present thread is a general inquiry as to the possibility of time travel, not:

“Does Einstein's Theory of Relativity Support Time Travel? "

 

The latter topic is based on the supposed time travel expertise of Mallet, whom you regard as “ renowned for being a nut.”

Given the question, “Can we travel into the past or the future?,”and my above specific challenges to actually doing so, I agree that anyone who believes it is possible is a nut, or at least confusing science with science fiction.

A technical objection:

"CTC’s?" is used without previous reference. Then the whole discussion of whether "CTCs” are allowed proceed without spelling it out. Typical for all who take pride in speaking a special language and condescending upon the stupidity of those not familiar with specific shop talk. The rule is (or should be) first spell out acronyms, then use them, especially on a public forum.

 

If you assume global hyperbolicity the question of existence of CTCs is settled immediately -- they don't.

But if you don’t automatically assume that space has shape (Oopse, ontology again).... even without CTC clarification... (I'll let this one dangle.)

 

I agree with “The Conqueror” that:

If time travel was possible, then certainly if anyone invents time travel machine say in 2042 then he should be talking with us!!

Anyone know of verified visitors from the future? If so I will gladly "eat my hat."

 

ajb:

Really, time machines should be seen as pushing our understanding of classical, semi-classical relativity and our notion of causality to the limit, rather than real attempts at contacting the past...

 

But the question at hand is about the possibility of those “real attempts.” Can we visit the past and future or not? (Ans: Not.)

 

ajb:

To paraphrase Brian Cox " even if the laws of physics do not prohibit time travel, that doesn’t mean to say it’s going to happen....

 

(and)... It is fair to say that within classical general relativity it is not obvious that time travel is not allowed.

But it is obvious to everyone but sci-fi fans and general relativity theorists... which does the latter no credit!

The test of the laws of physics must be empirical verification. If it is impossible to visit dead ancestors before they died (visiting the past) or to make a killing on horse races (visiting the future), then it is safe to say that time travel is not possible.

The laws of physics don’t prohibit the “existence of god” either, but I will remain atheist on the grounds of no positive proof (and the conviction that it is a silly supernatural mythology) rather than lack of proving a negative.

Edited May 20, 2011 by owl

[Newbies_Kid]

I'm confidently say time traveling is impossible. If human really want to travel through time i challenge them to create a 4D space first. For me, only God can control time.

[MigL]

I find it funny that in this thread regarding time travel you insist on proof and empirical verification. I.e. no visitors from the future, so time travel is impossible.

Yet on the other thread regarding the topology of space/time ( the locked one in relativity forum ) you find it convenient to disregard all the many verifications of curved space/time and GR that have been made since 1916. In that one you base your arguments on ontology, the philosophical study of reality, instead of the proven science.

 

Myself, I have a 'gut' feeling that time travel is impossible, although I cannot prove or disprove it. My only objections to time travel are the possibility of violation of causality, i.e. you cannot have something happen that hasn't been caused yet, and the fact that the dimension of time is not like the other three spatial dimensions in our GR description of it. Maybe GR isn't a complete picture of it yet, since in some circumstances it allows for CTL.

Incidentally the term closed timelike loops was coined by Kip Thorne when he started investigating the possibility of travel through wormholes, which when arranged in a certain way do permit time travel. The media thought this very sensational so he changed the term from travelling through time, to closed timelike loops. Notice that the equations permit it, as to wether its actually possible, who knows. ( Relativistic QM equations also permit Tachyons which always travel faster than c and move backwards in time, but do they exist ??? )

 

 

[DrRocket]

I find it funny that in this thread regarding time travel you insist on proof and empirical verification. I.e. no visitors from the future, so time travel is impossible.

Yet on the other thread regarding the topology of space/time ( the locked one in relativity forum ) you find it convenient to disregard all the many verifications of curved space/time and GR that have been made since 1916. In that one you base your arguments on ontology, the philosophical study of reality, instead of the proven science.

 

Myself, I have a 'gut' feeling that time travel is impossible, although I cannot prove or disprove it. My only objections to time travel are the possibility of violation of causality, i.e. you cannot have something happen that hasn't been caused yet, and the fact that the dimension of time is not like the other three spatial dimensions in our GR description of it. Maybe GR isn't a complete picture of it yet, since in some circumstances it allows for CTL.

Incidentally the term closed timelike loops was coined by Kip Thorne when he started investigating the possibility of travel through wormholes, which when arranged in a certain way do permit time travel. The media thought this very sensational so he changed the term from travelling through time, to closed timelike loops. Notice that the equations permit it, as to wether its actually possible, who knows. ( Relativistic QM equations also permit Tachyons which always travel faster than c and move backwards in time, but do they exist ??? )

 

 

 

Pretty much everyone expects that something like the chronology protection conjecture will be shown to be true. But it is not straightforward. Closed timelike curves do exist in some exotic solutions to the Einstein field equations. Gödel's lambda dust space, the Tipler cylinder and Kerr black holes have CTCs.

 

On the other hand Hawking showed that if the weak energy condition holds then there are no CTCs.

 

Quantum fields, as I understand it, generally do not conform to the weak energy condition (ajb chime in) so chronology protection may well not hold at the quantum level. There are Feynman diagrams that include non-causal branches.

 

I have no idea if Thorne coined "closed timelike curves", but it is natural terminology for dealing with the geometry of a Lorentzian manifold.

 

There is good reason to demand a mathematical proof based on general relativity. Odd things really do happen. When black hole solutions were first found, many physicists, Einstein included, did not believe that physical black holes would exist. One learns in physics by pushing the limits of what is known and investigating situations that might be termed "exotic". Exotic is not necessarily impossible.

 

Any proof of the chronology protection conjecture will have to include some conditions that constrain the admissible solutions to the Einstein field equations. The known exotic solutions with CTCs serve to demonstrate that fact. General relativity alone is not enough.

 

In a sense the deep problem is that causality appears to not strictly hold at the quantum level, but it seems to apply in "normal" macroscopic situations. So, where is line between the quantum world and the macroscopic world where causality kicks in ? This is well worth understanding.

Edited May 22, 2011 by DrRocket

[IM Egdall]

DrRocket - Excellent summary on time travel issues.

 

I edited to add these thoughts:

 

Special Relativity - You travel from Earth to outer space and back in a rocket at say 87% the speed of light. Say to you on the rocket the round trip takes 5 years. But per special relativity, to us on Earth 10 years have gone by. This is because time runs faster on the Earth than it does on the rocket.

 

Say you leave in the year 2020. Per your rocket calendar, when you arrive back on Earth it is the year 2025. But calendars on Earth say it is the year 2030. So you arrive back on Earth 5 years into the future!

 

An everyday example: You go to work or school but your roommate stays at home. Your motion to and from work or school means your time runs a tiny bit slower than time for your stationary roommate. So you arrive back at home at the end of the day a tiny bit into the future. We are all time travelers.

 

General Relativity - Here we travel into the future and into the past. Say you go to the top of a mountain. While there, your time runs (a little bit) slower than time at sea level.

 

At some later time, I go to the mountain top. Since time runs faster on the mountain top, I find more time has gone by on the mountain top than at sea-level. So I have traveled into the future.

 

But what if I stay at sea-level and at some later time, you travel from the mountain top to sea-level. Because time runs slower on the surface than on the mountain top, you effectively travel into the past! But you cannot return to the surface to a time that is before when you left - casuality is maintained.

 

(For simplicity,we ignore the effects on time of motion up and down the mountain here.)

 

So whenever we are in motion or change altitude, we are time travelling! And this is not a possible outcome of relativity, but a definite outcome based on experimentally verified time effects.

Edited May 22, 2011 by I ME

[owl]

I ME,

We all know that clocks run faster or slower under different conditions, as you described. ("Time dilation.")

I suspect that people age more slowly in high speed (etc.) conditions as well.

But the question is still unresolved for me how this proves that "time runs faster (or slower)" under the different conditions you mention. Is it just semantics or is there some actual entity, "time" which changes under these different conditions? Please refer to my "Ontology of Time" thread in the "speculations" section for the background behind my question.

 

To be more specific... regarding your statement (and apparently accepted relativity theory... as per "the twins paradox" and such):

Say to you on the rocket the round trip takes 5 years. But per special relativity, to us on Earth 10 years have gone by.

 

Is there not a "reality check" here... that a year is one orbit of earth around sun? Speeding out into space and back in a rocket does not make ten earth orbits into five just because the rocket's clock and calendar says that only five years have elapsed.

Or regarding your thought experiment:

Say you leave in the year 2020. Per your rocket calendar, when you arrive back on Earth it is the year 2025. But calendars on Earth say it is the year 2030. So you arrive back on Earth 5 years into the future!

What could the last statement possibly mean? You come back to an Earth in which events have not yet happened and will not happen for five more years? Does this make any sense at all? Not to me!

What am I missing here?

[DrRocket]

What am I missing here?

 

You are missing the fact that time is not universal. Time is a local concept and two accurate clocks can measure very different "proper time" intervals between two given points in spacetime. Time neither "speeds up" nor "slows down" -- speed presupposes ability to reckon time and "time per unit time" is meaningless.

 

Time is NOT Newton's "flowing river" that is the same everywhere for everyone.

 

Relativity was a revolutionary theory of the very nature of space and time. The result is that neither space nor time are global. There is no way to understand or explain this without recourse to abstract mathematics. Should you ever want to try to understand, Gravitation by Misner, Thorne and Wheeler is the classic source.

[owl]

DrRocket:

You are missing the fact that time is not universal. Time is a local concept and two accurate clocks can measure very different "proper time" intervals between two given points in spacetime.

I must question your use of "fact" in this context. Do you discard presentism out of hand, or have you studied it at all? "Present" means "now", and now is not a locally unique "environment" but everywhere present at once, without regard for lightspeed and the information it conveys (The province of relativity.)

 

I'm interrupted by life's priorities so must cut this reply short. The above illustrates my point anyway.

And, again, "spacetime" is not such a malleable matter of fact as relativity generally assumes... the other conversation which I will not again mention here in this forum section.

Edited May 24, 2011 by owl

[rktpro]

I wish Einstein were also a member of this forum.

[DrRocket]

DrRocket:

 

I must question your use of "fact" in this context. Do you discard presentism out of hand, or have you studied it at all? "Present" means "now", and now is not a locally unique "environment" but everywhere present at once, without regard for lightspeed and the information it conveys (The province of relativity.)

 

I'm interrupted by life's priorities so must cut this reply short. The above illustrates my point anyway.

And, again, "spacetime" is not such a malleable matter of fact as relativity generally assumes... the other conversation which I will not again mention here in this forum section.

 

"Nuts" -- Anthony C. McAuliffe

Edited May 25, 2011 by DrRocket

[Widdekind]

It is expected that you can only send a message back in time only as far back as when the time machine was created. Thus, we will not get any messages until the machine is turned on.

 

Paul Davies discusses this (briefly) in his book Eerie Silence, which references his previous book How to Build a Time Machine. Lay readers may learn more, from a popular introduction, to the time-travel topic.

[owl]

My question, "What am I missing here?" in post 67 replying to I ME was a serious question about how ten years, defined as Earth orbits around the sun, can become five years (for the rocketeers) by virtue of a fast round trip in a rocket ship which slows down their clock and calendar.

I also asked what it means to arrive back on earth five years in the future, i.e., before the events of those five years have even happened. These are reasonable questions, and calling me "nuts" for asking them is not worthy of a science forum, and it seems to violate Admin's recent warning against name calling here.

As a retired psychologist, my professional opinion is that believing those situations to be possible demonstrates a state of mind out of touch with reality... no personal insult intended.

And in accordance with the admin advice given me, I will not re-engage the ontology of spacetime topic again outside the philosophy section, regardless of DrRocket's persistence in insulting me.

(...and veiling the insult as a McAuliffe quote does not make it OK.)

Edit for correction. DrR's insult was directed to my reply to his last post, not to my reply to I ME. But the insult was just as inappropriate in either case.

And, just to be clear, the present is universal, now everywhere, and time is the "clocked" duration of events from one "now" to another, between clicks of the "timer's" stopwatch... not some stuff woven together with space... which is... debatable as to what it is. Enough of that already.

Edited May 25, 2011 by owl

[DrRocket]

My question, "What am I missing here?" in post 67 replying to I ME was a serious question about how ten years, defined as Earth orbits around the sun, can become five years (for the rocketeers) by virtue of a fast round trip in a rocket ship which slows down their clock and calendar.

I also asked what it means to arrive back on earth five years in the future, i.e., before the events of those five years have even happened. These are reasonable questions, and calling me "nuts" for asking them is not worthy of a science forum, and it seems to violate Admin's recent warning against name calling here.

As a retired psychologist, my professional opinion is that believing those situations to be possible demonstrates a state of mind out of touch with reality... no personal insult intended.

And in accordance with the admin advice given me, I will not re-engage the ontology of spacetime topic again outside the philosophy section, regardless of DrRocket's persistence in insulting me.

(...and veiling the insult as a McAuliffe quote does not make it OK.)

Edit for correction. DrR's insult was directed to my reply to his last post, not to my reply to I ME. But the insult was just as inappropriate in either case.

And, just to be clear, the present is universal, now everywhere, and time is the "clocked" duration of events from one "now" to another, between clicks of the "timer's" stopwatch... not some stuff woven together with space... which is... debatable as to what it is. Enough of that already.

 

You need to brush up your history and dial down the paranoia. "Nuts" was the exact response of General Anthony McAuliffe when presented an unreasonable position by the Geremans during the Seige of Bastogne during the Battle of the Bulge.. It is simply a categorical denial.

[owl]

I ME,

Please reply to my post 67.

Have our variable clocks become the standard for relativity arguments based on "time dilation", or is a year still one earth orbit? If the latter, then days, hours, minutes, seconds, & on down are fractions thereof standardized by the above natural cycles ? If the latter, can we not admit instrument error for clocks and then credit relativity with corrective math for all such variation?

 

More generally (to the forum) regarding time, anyone interested in presentism as relevant to "time travel?"

Specifically, was Einstein correct in concluding that the past, present, and future all exist simultaneously as per the "world lines" of everything in the universe (including all three) all existing at once.

Ref from article, "Timelessness":

http://everythingforever.com/einstein.htm

Surprising as it may be to most non-scientists and even to some scientists, Albert Einstein concluded in his later years that the past, present, and future all exist simultaneously.

and

"...for us physicists believe the separation between past, present, and future is only an illusion, although a convincing one."

 

If I may interject a philosophical comment, the above not only implies strict determinism for the whole universe, but says that everything that ever existed still exists, which is blatantly absurd... as is "eternalism" in general as a philosophy of time.

 

In contrast, here is Wikipedia's intro to Presentism:

In the philosophy of time, presentism is the theory that only present things exist, and future and past things are unreal. The opposite of presentism is 'eternalism', which is the belief that things in the past and things yet to come exist eternally.[1] Presentism is compatible with Galilean relativity, in which time is independent of space but is probably incompatible with Lorentzian/Einsteinian relativity in conjunction with certain other philosophical theses which many find uncontroversial.

The controversy is very "real," which means that relativity's version of time (etc.) is not the matter-of-fact as presented here, particulary by DrRocket.

BTW, nice try, Doctor, on weaseling out of responsibility for the "nuts" insult, but the veil was very thin, and I really don't "need" to "brush up" on my history or defend my sanity to know that you meant it as an insult. Further, "categorical denials" are not arguments addressing the points I have made in recent replies to I ME and to you.