Musings on Time Travel

[MalcolmM]

I'm sure I read this thread about 350 years ago and was about to reply when I got distracted by an apple hitting me on the head

[ollypenrice]

If we travelled back to a time in which we were there as a returner, it would not be the same past as a past in which we were not there as a returner. The decision to return or not return can therefore create two pasts.

I think our incomprehension of time is the biggest intellectual obstacle we face.

Olly

[Mr Spock]

I'm from 500 years in the future. Unfortunately the time machine I used to get here won't be invented for another 500 years, so, I'm stuck here in the dark ages.

[Ags]

I'm from one femtosecond in the past.

[Alien 13]

37 minutes ago, ollypenrice said:

I think our incomprehension of time is the biggest intellectual obstacle we face.

Olly

Would agree, watched a vid the other day that suggested that it was time itself that gave rise to gravity in space -time.

Alan

[cloudsweeper]

14 minutes ago, Alien 13 said:

Would agree, watched a vid the other day that suggested that it was time itself that gave rise to gravity in space -time.

Alan

Yes.  Mass bends time; bent (dilated) time causes gravity.   (And no, I don't pretend to understand this.)

Re Olly's recent post - yes, the only way to go to the past must be as an observer.

Doug.

[andrew s]

1 hour ago, ollypenrice said:

I think our incomprehension of time is the biggest intellectual obstacle we face.

Olly

I think Einstein had it about right when he said time is what a clock measures and space is what a stick measures (or words to that effect ).

In GR energy density, including mass, bends spacetime not space or time individually .

In some fundamental sense we don't understand anything totally. We just get used to using the concept.  They are just terms in "models" we used to make sense of the world. 

Regards  Andrew 

[ollypenrice]

29 minutes ago, cloudsweeper said:

Yes.  Mass bends time; bent (dilated) time causes gravity.   (And no, I don't pretend to understand this.)

Re Olly's recent post - yes, the only way to go to the past must be as an observer.

Doug.

 In popular imagination a time traveller goes back in time as a separate entity from the self who arrived at the point when he or she began their journey into the past. There are, therefore, two of them co-existing at the same time on this backward journey, one travelling forwards and a different one travelling backwards. This seems odd... And, while travelling backwards, what does the time traveller see? People moving and speaking like a film played in reverse?

Perhaps travelling backwards in time is an unpleasant and incomprehensible experience because the laws of time travel turn out to require you to replay your existing experiences backwards without being able to become a separate entity? Not a very rewarding experience, being stuck inside a self walking and speaking and thinking backwards in a world in which everyone is doing likewise. And then, after this, you simply replay your previous experiences in the right direction without being aware of replaying them (because you weren't aware of replaying them first time around!)  Ah! 

...and here's the thing: how do you know this isn't exactly what you are doing while reading this?

Olly

Edited April 8, 2022 by ollypenrice

[saac]

19 minutes ago, ollypenrice said:

 In popular imagination a time traveller goes back in time as a separate entity from the self who arrived at the point when he or she began their journey into the past. There are, therefore, two of them co-existing at the same time on this backward journey, one travelling forwards and a different one travelling backwards. This seems odd... And, while travelling backwards, what does the time traveller see? People moving and speaking like a film played in reverse?

Perhaps travelling backwards in time is an unpleasant and incomprehensible experience because the laws of time travel turn out to require you to replay your existing experiences backwards without being able to become a separate entity? Not a very rewarding experience, being stuck inside a self walking and speaking and thinking backwards in a world in which everyone is doing likewise. And then, after this, you simply replay your previous experiences in the right direction without being aware of replaying them (because you weren't aware of replaying them first time around!)  Ah! 

...and here's the thing: how do you know this isn't exactly what you are doing while reading this?

Olly

Because that is what happens when I have had too much whisky, and I haven't yet had too much whisky  

Jim

[cloudsweeper]

39 minutes ago, andrew s said:

we don't understand anything totally. We just get used to using the concept.  They are just terms in "models" we used to make sense of the world. 

Regards  Andrew 

..........which makes me think of the wave/particle thing.  Particle when created; wave when propagating - only because we want behaviour to fit models we are at ease with.  In reality, the nature of EM radiation is something we can't properly comprehend.

Doug.

[andrew s]

 

11 hours ago, cloudsweeper said:

..........which makes me think of the wave/particle thing.  Particle when created; wave when propagating - only because we want behaviour to fit models we are at ease with.  In reality, the nature of EM radiation is something we can't properly comprehend.

Doug.

True but we have some very accurate models that can predict outcomes with exquisite precision.  Regards Andrew 

Edited April 9, 2022 by andrew s

[iantaylor2uk]

3 hours ago, andrew s said:

 

True but we have some very accurate models that can predict outcomes with exquisite precision.  Regards Andrew 

And we can also measure the speed of photons even though some people believe they don't exist during their motion!

[ollypenrice]

I'm still pondering the time frame of the H G Wellsian traveller going backwards in time. He's not going backwards in his 'pre-time-travel' time frame because that would simply mean running himself and his experience in reverse. What he must be doing is continuing to move forwards in his own new time frame (he opens the time machine door, then steps out, then looks around, etc...)  Now, what if he only went back half an hour to the time when he was about to get into the damned thing? He'd be able to watch himself doing so. There would be two of him. Does this mean that the time traveller's time frame and his original are now parallel? (He can't re-join his old time frame because there would be two of him.)

The more I think about this, the more convinced I am that H G Wells must have been making it up.

Shocking.

Olly

[saac]

2 hours ago, ollypenrice said:

I'm still pondering the time frame of the H G Wellsian traveller going backwards in time. He's not going backwards in his 'pre-time-travel' time frame because that would simply mean running himself and his experience in reverse. What he must be doing is continuing to move forwards in his own new time frame (he opens the time machine door, then steps out, then looks around, etc...)  Now, what if he only went back half an hour to the time when he was about to get into the damned thing? He'd be able to watch himself doing so. There would be two of him. Does this mean that the time traveller's time frame and his original are now parallel? (He can't re-join his old time frame because there would be two of him.)

The more I think about this, the more convinced I am that H G Wells must have been making it up.

Shocking.

Olly

The moment he time travels (punches it) he isolates himself from the frame of reference ( time line ) in which he existed to date; he becomes a dislocated frame of reference in time as he travels. If he travels to the moment where he opened the time machine door, then that is the past with respect to his old reference frame (the timeline he left) and simultaneously it is both his future and present with respect to his dislocated timeline.  As he lingers and watches his past self open the door to the time machine his dislocated timeline merges with his past timeline .  He now finds his future, present and past coalescing to a common timeline.  The universe wasn't constructed to hold these two versions of our time traveller (matter, energy and time existing where it should not). Whether it was the Pauli exclusion principle, the first law of thermo dynamics or simply a need to maintain an energy equilibrium the universe therefore isolates him , he is unable to interact with this timeline.  Like a virtual particle he appears to instantly disappear paying back the energy he stole.  Our time traveller is confined to only exist in his isolated timeline forever travelling, never existing outside of his own island of time  

Jim  

 

Edited April 9, 2022 by saac

[ollypenrice]

1 hour ago, saac said:

The moment he time travels (punches it) he isolates himself from the frame of reference ( time line ) in which he existed to date; he becomes a dislocated frame of reference in time as he travels. If he travels to the moment where he opened the time machine door, then that is the past with respect to his old reference frame (the timeline he left) and simultaneously it is both his future and present with respect to his dislocated timeline.  As he lingers and watches his past self open the door to the time machine his dislocated timeline merges with his past timeline .  He now finds his future, present and past coalescing to a common timeline.  The universe wasn't constructed to hold these two versions of our time traveller (matter, energy and time existing where it should not). Whether it was the Pauli exclusion principle, the first law of thermo dynamics or simply a need to maintain an energy equilibrium the universe therefore isolates him , he is unable to interact with this timeline.  Like a virtual particle he appears to instantly disappear paying back the energy he stole.  Our time traveller is confined to only exist in his isolated timeline forever travelling, never existing outside of his own island of time  

Jim  

 

But he got back to narrate the story!  As an Archbishop in the House of Lords said about Gulliver's Travels, 'For my part, I don't believe a word of it.' *

Olly

*This is honestly true, by the way.

[saac]

53 minutes ago, ollypenrice said:

But he got back to narrate the story!  As an Archbishop in the House of Lords said about Gulliver's Travels, 'For my part, I don't believe a word of it.' *

Olly

*This is honestly true, by the way.

Maybe what we see as ghosts are actually time travellers making the most of things before the universe rips them out of exitance in our timeline!    I'm with the Archbishop, I don't believe it either  

Jim

[KenG]

I raised this in an earlier post.  As I see it, it would be impossible to exist in two places at once, so what happens if our traveller goes back say, five hundred years, does a bit of looking around for a couple of weeks and then returns to his/her point of departure? Would it be as though they had never left, that they return in the same instant they departed? And what would happen to them in the time zone they travelled to? Would everything be frozen at the instant of their arrival so that however long they lingered, nothing would change? Again, I couldn't see them travelling as a person, rather in a disassembled state - a projection if you like - that would hopefully all come back together when they get to where they're going, which raises all manner of problems that it's too late to discuss tonight.

Anyway, just musing. Back to the wine🍷.

[Ags]

I understand not everyone on this thread is familiar with the finer points of time travel, but having worked for 7 years in Starfleet's Temporal Directorate (many more years than that counting excursions), I would like to say if you are travelling into the past or the future, it is standard protocol to return 5 minutes before you left. That way, if you don't survive the trip, you know in advance and therefore simply never set out on your journey.

Edited April 10, 2022 by Ags

[Elp]

But if you are aware of your 5 minute self won't the space time continuum be destroyed and life as we know it cease to exist?

[ollypenrice]

17 hours ago, Ags said:

I understand not everyone on this thread is familiar with the finer points of time travel, but having worked for 7 years in Starfleet's Temporal Directorate (many more years than that counting excursions), I would like to say if you are travelling into the past or the future, it is standard protocol to return 5 minutes before you left. That way, if you don't survive the trip, you know in advance and therefore simply never set out on your journey.

Tracey:  This is Tracey of the wheel clamping agency. How may I help you?

Dr Who: Ah, my vehicle has been clamped and I need to liberate it.

Tracey: Where did you park the car?

Dr Who: I prefer to call it a vehicle. It's in one of the outer arms of the galaxy Beta Centuron.

Tracey: Do you have the postcode?

Dr Who: No.

Tracey: I see. So when did you park the vehicle?

Dr Who: Tomorrow.

(From a radio comedy series on the UK's Radio 4.  Tracey was a real person at work and the guy doing Dr Who got the voice just right. At some point in every phone call the victim would ask the caller's name and be told, 'The Doctor,' at which point they would invariably ask, 'Doctor who?'

🤣lly

[Miguelo65]

On 29/03/2022 at 19:13, saac said:

My personal time machine is my inner picture of myself that I  carry in my head. In there, I see myself as I was when in my 20s.  Sadly, one look in the mirror brings me back to the present .

Welcome to Entropy

[Ags]

21 hours ago, Elp said:

But if you are aware of your 5 minute self won't the space time continuum be destroyed and life as we know it cease to exist?

But that has never will have happened.

[Zermelo]

56 minutes ago, Ags said:

But that has never will have happened

I've lost track of this thread now, so this may have been quoted already (or may have been in another timeline).
Douglas Adams, of course, identified the real issue:

"One of the major problems encountered in time travel is not that of becoming your own father or mother. There is no problem in becoming your own father or mother that a broad-minded and well-adjusted family can't cope with. There is no problem with changing the course of history—the course of history does not change because it all fits together like a jigsaw. All the important changes have happened before the things they were supposed to change and it all sorts itself out in the end.

The major problem is simply one of grammar, and the main work to consult in this matter is Dr. Dan Streetmentioner's Time Traveler's Handbook of 1001 Tense Formations. It will tell you, for instance, how to describe something that was about to happen to you in the past before you avoided it by time-jumping forward two days in order to avoid it. The event will be descibed differently according to whether you are talking about it from the standpoint of your own natural time, from a time in the further future, or a time in the further past and is futher complicated by the possibility of conducting conversations while you are actually traveling from one time to another with the intention of becoming your own mother or father.

Most readers get as far as the Future Semiconditionally Modified Subinverted Plagal Past Subjunctive Intentional before giving up; and in fact in later editions of the book all pages beyond this point have been left blank to save on printing costs.

The Hitchhiker's Guide to the Galaxy skips lightly over this tangle of academic abstraction, pausing only to note that the term "Future Perfect" has been abandoned since it was discovered not to be."

 

 

 

Edited April 11, 2022 by Zermelo

[saac]

8 minutes ago, Zermelo said:

I've lost track of this thread now, so this may have been quoted already (or may have been in another timeline).
Douglas Adams, of course, identified the real issue:

"One of the major problems encountered in time travel is not that of becoming your own father or mother. There is no problem in becoming your own father or mother that a broad-minded and well-adjusted family can't cope with. There is no problem with changing the course of history—the course of history does not change because it all fits together like a jigsaw. All the important changes have happened before the things they were supposed to change and it all sorts itself out in the end.

The major problem is simply one of grammar, and the main work to consult in this matter is Dr. Dan Streetmentioner's Time Traveler's Handbook of 1001 Tense Formations. It will tell you, for instance, how to describe something that was about to happen to you in the past before you avoided it by time-jumping forward two days in order to avoid it. The event will be descibed differently according to whether you are talking about it from the standpoint of your own natural time, from a time in the further future, or a time in the further past and is futher complicated by the possibility of conducting conversations while you are actually traveling from one time to another with the intention of becoming your own mother or father.

Most readers get as far as the Future Semiconditionally Modified Subinverted Plagal Past Subjunctive Intentional before giving up; and in fact in later editions of the book all pages beyond this point have been left blank to save on printing costs.

The Hitchhiker's Guide to the Galaxy skips lightly over this tangle of academic abstraction, pausing only to note that the term "Future Perfect" has been abandoned since it was discovered not to be."

 

 

 

Or as Sheldon Cooper put it:

Jim

 

[ollypenrice]

10 hours ago, Zermelo said:

I've lost track of this thread now,

Hardly surprising since it's a trackless waste....*

The notion of a past, a moving present and a future is known to philosophers and theoretical physicists as The Tensed Theory of Time. Your Douglas Adams quotation tells us why!

(Trivia: one of my best friends was at school with Douglas Adams but, prodigious as this information is, it must take second place in my repertoire to the fact that my cousin is the bass player in Jethro Tull.)

Olly

* of time...