Time Travel/Bootstrap Paradox?

[Neogaia777]

@sjastro @SelfSim @Hans Blaster

Thanks for your time guys, I greatly appreciate it, as always.

Take Care/God Bless.

 

[Neogaia777]

You know, I've been mentioning some pretty large, vast differences/distances, but this could probably be tested (or proven/disproven) on a lot much more smaller, and much more local, scales?

Take another planet in our solar system for example, it's so many light minutes away, correct? Well, can we somehow show (or prove) whether those images/distances are also that "old" or not? Yes? No?

Or whether or not the "time" there from our present position would also need to be adjusted/measured/accounted for or not (our present time plus however many light minutes it was away or not), or to be in it's right or correct time, or not, etc? Because, if so, then wouldn't that also have to be true of other much larger distances also? Regardless, or irregardless, or however far they were away (or close) they were or not?

We might even be able to use differences/distances even much smaller than that maybe to show whether this was true or not true or not? Light seconds or less maybe, etc? Either way, if it is true, then wouldn't it also have to be true of other differences/distances also? Regardless (or irregardless) of what those differences/distances were also?

Take Care/God Bless.

 

[SelfSim]

You know, I've been mentioning some pretty large, vast differences/distances, but this could probably be tested (or proven/disproven) on a lot much more smaller, and much more local, scales?

Take another planet in our solar system for example, it's so many light minutes away, correct? Well, can we somehow show (or prove) whether those images/distances are also that "old" or not? Yes? No?

Or whether or not the "time" there from our present position would also need to be adjusted/measured/accounted for or not (our present time plus however many light minutes it was away or not), or to be in it's right or correct time, or not, etc? Because, if so, then wouldn't that also have to be true of other much larger distances also? Regardless, or irregardless, or however far they were away (or close) they were or not?

We might even be able to use differences/distances even much smaller than that maybe to show whether this was true or not true or not? Light seconds or less maybe, etc? Either way, if it is true, then wouldn't it also have to be true of other differences/distances also? Regardless (or irregardless) of what those differences/distances were also?

Take Care/God Bless.

The syncronisation issues between distant spacecraft and Earth originated control commands would have to have been solved for Voyager 1 and 2, and more recently for the New Horizons/Pluto/Kuiper Belt spacecraft.

(I think I recall that the Voyager spacecraft only have onboard oscillator counters which are downloaded to Earth and translated to UTC time upon arrival .. ie: they have no real onboard clocks(?) .. but New Horizons has an ultrastable oscillator onboard and its synchronisation with Earth is critical for successfully achieving its mission activities).

 

[Neogaia777]

The syncronisation issues between distant spacecraft and Earth originated control commands would have to have been solved for Voyager 1 and 2, and more recently for the New Horizons/Pluto/Kuiper Belt spacecraft.

(I think I recall that the Voyager spacecraft only have onboard oscillator counters which are downloaded to Earth and translated to UTC time upon arrival .. ie: they have no real onboard clocks(?) .. but New Horizons has an ultrastable oscillator onboard and its synchronisation with Earth is critical for successfully achieving its mission activities).

Are any light distances that we are viewing from our present position, are they also that "old" or not?

 

[SelfSim]

Are any light distances that we are viewing from our present position, are they also that "old" or not?

Voyager 1 is approximately 0.0021 light-years from Earth, and Voyager 2 is about 0.0018 light-years from Earth.
New Horizons is approximately 0.0024 light-years away from Earth.
ETA: Hang on .. that can't be right!

ETA#2: Yeah .. New Horizons is only 0.0009665 light years distant, 61.128 AUs. Voyager 1 is 166.34 AUs distant.

 

[Neogaia777]

Voyager 1 is approximately 0.0021 light-years from Earth, and Voyager 2 is about 0.0018 light-years from Earth.
New Horizons is approximately 0.0024 light-years away from Earth.
ETA: Hang on .. that can't be right!

I'll claim my ignorance on not right now knowing which was launched first, or later, or after without Googling it right now, etc.

Maybe you can fill me in?

Take Care.

 

[Neogaia777]

Voyager 1 is approximately 0.0021 light-years from Earth, and Voyager 2 is about 0.0018 light-years from Earth.
New Horizons is approximately 0.0024 light-years away from Earth.
ETA: Hang on .. that can't be right!

ETA#2: Yeah .. New Horizons is only 0.0009665 light years distant, 61.128 AUs. Voyager 1 is 166.34 AUs distant.

That makes much more sense, lol.

Otherwise I was going to ask if it was maybe launched in a different direction, or was on the other side of the solar system right now? But I still don't think that would have made up for it though, lol.

Take Care.

 

[SelfSim]

I found a pretty old New Horizons design document (published 2008) .. (called: 'The New Horizons Spacecraft').

It says:

5.2. TIME MANAGEMENT
The accuracy of the correlation of MET {Mission Elapsed Time} to Universal Time (UT) is of major importance to support navigation, G&C activities, and the collection of science data. The ultrastable oscillator (USO) used as the onboard source of a 1 pulse per second (PPS) signal maintains the spacecraft time base. Careful design of the ground to MET clock register in the C&DH {Command Data and Handling} system ensures onboard correlation of better than ±4 seconds when the spacecraft is at Pluto (a 9 hour round trip light time delay). Science instrument time correlation (postfacto) requirements are ±10 ms for REX, LORRI, Ralph, and Alice. Postlaunch measurements in July 2006 verified that the postfacto timing correlation is well within this requirement.

Not quite sure how this intersects with your question but the design is to achieve synchronisation between the spacecraft, ultra stable oscillator clock and a ground based timekeeping clock. I guess what they can demonstrate is that an uploaded command to be executed autonomously by the spacecraft, would occur within ±4 seconds of the ground expectation of the scheduled execution time .. (with a spacecraft distance separation of a 4.5 hour one-way light transit time).

By way of a rough comparison, I've seen calculations which assume a speed of Voyager 1 as being 3.595 AU per year over, say, a 35 year period, which returns the result that the Voyager 1 clock would have been slower by 1.8 seconds compared to a clock on Earth (using the SR time dilation eqn).

 

[Neogaia777]

I found a pretty old New Horizons design document (published 2008) .. (called: 'The New Horizons Spacecraft').

It says:


Not quite sure how this intersects with your question but the design is to achieve synchronisation between the spacecraft, ultra stable oscillator clock and a ground based timekeeping clock. I guess what they can demonstrate is that an uploaded command to be executed autonomously by the spacecraft, would occur within ±4 seconds of the ground expectation of the scheduled execution time .. (with a spacecraft distance separation of a 4.5 hour one-way light transit time).

By way of a rough comparison, I've seen calculations which assume a speed of Voyager 1 as being 3.595 AU per year over, say, a 35 year period, which returns the result that the Voyager 1 clock would have been slower by 1.8 seconds compared to a clock on Earth (using the SR time dilation eqn).

That's cool/interesting, and I appreciate it, but does it answer my question though?

Thanks/Take Care.

 

[Neogaia777]

By way of a rough comparison, I've seen calculations which assume a speed of Voyager 1 as being 3.595 AU per year over, say, a 35 year period, which returns the result that the Voyager 1 clock would have been slower by 1.8 seconds compared to a clock on Earth (using the SR time dilation eqn).

So did Voyager 1's clock run or operate slower because it was in motion, or was moving along at that velocity/speed, but nowhere else did the clocks ever change?

Because, if so, then this would indicate that the passage of time only ever slows down for the one in motion, and moving at faster speeds/velocities, but for no one anywhere else does it ever change ever, etc? Which was another of my questions, etc?

Take Care.

 

[SelfSim]

So did Voyager 1's clock run or operate slower because it was in motion, or was moving along at that velocity/speed, but nowhere else did the clocks ever change?

There are two effects to consider (ie: if the Voyagers had an onboard clock - they don't):

i) SR - In the case of Voyager it would run slower than clocks here on Earth assuming an average of 3.595 AU per year velocity for the entire 35 years. (The actual velocity difference is not so easy to calculate accurately because it varies depending on the probe flight trajectory and on Earth's orbital trajectory and on the thermal issues found to affect the Voyager's 'peculiar' velocities);

ii) GR - In Voyager's case, (assuming the above average velocity for 35 years), clocks on the Earth (in the sun's gravity well) run slower than the clock on the Voyager 1. (The actual difference however would require integrating along the probe trajectory path to determine the distance separation between it and Earth at any given time).

(i) and (ii) are generally additive. I'm not sure about the magnitude of the thermal 'peculiar' velocity but the GR effect, I think, is the greater of the two relativistic impacts. (This may be why the New Horizons clock correlation difference of ±4 seconds is quoted in its performance specs .. I can't confirm that however .. this may just be the impact of the onboard oscillator drift over a nominal mission duration).

The heliocentric frame could be used as a simplifying reference frame here too, I suppose.

Because, if so, then this would indicate that the passage of time only ever slows down for the one in motion, and moving at faster speeds/velocities, but for no one anywhere else does it ever change ever, etc? Which was another of my questions, etc?

The gravitational time dilation effect has been verified in GPS satellite vs ground based clock correlations and also by the updated Eddington experiment. SR dilation is demonstrated by observed particle lifetimes in accelerators (as posted previously by @sjastro).

 

[Neogaia777]

There are two effects to consider (ie: if the Voyagers had an onboard clock - they don't):

i) SR - In general, it would run faster than clocks here on Earth because of the velocity difference. (The actual velocity difference is not so easy to calculate accurately because it varies depending on the probe flight trajectory and on Earth's orbital trajectory and on the thermal issues found to affect the Voyager's 'peculiar' velocities);

ii) GR - In general, clocks on the Earth (in the sun's gravity well) run slower than the clock on the Voyager 1. (The actual difference however would require integrating along the probe trajectory path to determine the distance separation between it and Earth at any given time).

(i) and (ii) are generally additive. I'm not sure about the magnitude of the thermal 'peculiar' velocity but the GR effect, I think, is the greater of the two relativistic impacts. (This may be why the New Horizons clock correlation difference of ±4 seconds is quoted in its performance specs .. I can't confirm that however .. this may just be the impact of the onboard oscillator drift over a nominal mission duration).

The heliocentric frame could be used as a simplifying reference frame here too, I suppose.

The gravitational time dilation effect has been verified in GPS satellite vs ground based clock correlations and also by the updated Eddington experiment. SR dilation is demonstrated by observed particle lifetimes in accelerators (as posted previously by @sjastro).

From the perspective of either one, nobody's own clocks would be or are running any slower or faster, etc, but when compared after stopping, or rejoining, the one that was moving through spacetime faster, would have been the one that was running slower the entire time, etc.

 

[Neogaia777]

There are two effects to consider (ie: if the Voyagers had an onboard clock - they don't):

i) SR - In general, it would run slower than clocks here on Earth because of the velocity difference. (The actual velocity difference is not so easy to calculate accurately because it varies depending on the probe flight trajectory and on Earth's orbital trajectory and on the thermal issues found to affect the Voyager's 'peculiar' velocities);

ii) GR - In general, clocks on the Earth (in the sun's gravity well) run slower than the clock on the Voyager 1. (The actual difference however would require integrating along the probe trajectory path to determine the distance separation between it and Earth at any given time).

(i) and (ii) are generally additive. I'm not sure about the magnitude of the thermal 'peculiar' velocity but the GR effect, I think, is the greater of the two relativistic impacts. (This may be why the New Horizons clock correlation difference of ±4 seconds is quoted in its performance specs .. I can't confirm that however .. this may just be the impact of the onboard oscillator drift over a nominal mission duration).

The heliocentric frame could be used as a simplifying reference frame here too, I suppose.

The gravitational time dilation effect has been verified in GPS satellite vs ground based clock correlations and also by the updated Eddington experiment. SR dilation is demonstrated by observed particle lifetimes in accelerators (as posted previously by @sjastro).

I've been trying to keep gravitational time dilation effects out of the equation for right now, as I'd like to only discuss one at a time. Which for right now, is about different velocities effects on time, or the time dilation effect as it relates to speed, or faster or slower movement through space-time, etc.

Not that I'm denying that gravitational time dilation effects are not also important, or aren't interesting, or do not most definitely play a part, or are not an important factor, etc, but for simplicities sake right now, let's just try to only tackle or only discuss one at a time.

 

[SelfSim]

I've been trying to keep gravitational time dilation effects out of the equation for right now, as I'd like to only discuss one at a time. Which for right now, is about different velocities effects on time, or the time dilation effect as it relates to speed, or faster or slower movement through space-time, etc.

Not that I'm denying that gravitational time dilation effects are not also important, or aren't interesting, or do not most definitely play a part, or are not an important factor, etc, but for simplicities sake right now, let's just try to only tackle or only discuss one at a time.

Ok .. fair enough.
As you can see, the best, most direct measure of onboard spacecraft clocks gets more complicated, (and more difficult to calculate and account for apparent time dilation), the deeper one goes into the spacecraft clock example.

 

[Neogaia777]

Ok .. fair enough.
As you can see, the best, most direct measure of onboard spacecraft clocks gets more complicated, (and more difficult to calculate and account for apparent time dilation), the deeper one goes into the spacecraft clock example.

Not really, from the perspective of both, no one's clocks are moving any faster or slower, but if you took a round trip in a spacecraft (with a clock on board) and you were traveling faster than most everything else around you through the fabric of spacetime the whole time, when you got back, your clock would be shown to have been experiencing the passage of time slower than the ones back on earth the entire time, etc. (Leaving gravitational time dilation effects out of it for the moment of course). But, from the perspective of both looking at their own clocks the entire time, no one's own clock was going any faster or slower the entire time, but that's only because in the ship, both the clock, and the one's looking at the clock on board, were experiencing the passage of time slower the entire time. And, because of this, also when they looked out of their window, or whatever, at everything else outside of them, including the clock on earth, etc, they think they would see them as having been experiencing the passage of time slower the entire time, but it was just only because they were the entire time, etc. (or even slower as they were headed away from Earth, and just a little bit faster as they were headed back) (but that might take a little bit more explaining, and will just only further complicate the issue, so let's just leave that out of it for now) but, point being, when the craft got back to earth, their clock on board would always be behind the one on earth, and that's because they experienced the passage of time slower than those on Earth just simply because of their velocity, or faster movement/travel through spacetime, etc. And while it may have appeared to them that everything else was experiencing the passage of time slower for a time, it actually wasn't, but was just only them experiencing the passage of time slower the entire time, just simply due to their faster velocity, or faster movement/travel through spacetime, etc.

Take Care.

 

[SelfSim]

Not really, from the perspective of both, no one's clocks are moving any faster or slower, but if you took a round trip in a spacecraft (with a clock on board) and you were traveling faster than most everything else around you through the fabric of spacetime the whole time, when you got back, your clock would be shown to have been experiencing the passage of time slower than the ones back on earth the entire time, etc. (Leaving gravitational time dilation effects out of it for the moment of course). But, from the perspective of both looking at their own clocks the entire time, no one's own clock was going any faster or slower the entire time, but that's only because in the ship, both the clock, and the one's looking at the clock on board, were experiencing the passage of time slower the entire time. And, because of this, also when they looked out of their window, or whatever, at everything else outside of them, including the clock on earth, etc, they think they would see them as having been experiencing the passage of time slower the entire time, but it was just only because they were the entire time, etc. (or even slower as they were headed away from Earth, and just a little bit faster as they were headed back) (but that might take a little bit more explaining, and will just only further complicate the issue, so let's just leave that out of it for now) but, point being, when the craft got back to earth, their clock on board would always be behind the one on earth, and that's because they experienced the passage of time slower than those on Earth just simply because of their velocity, or faster movement/travel through spacetime, etc. And while it may have appeared to them that everything else was experiencing the passage of time slower for a time, it actually wasn't, but was just only them experiencing the passage of time slower the entire time, just simply due to their faster velocity, or faster movement/travel through spacetime, etc.

Take Care.

Let's just stick with standard descriptions of the Twins Paradox, eh?

I mean, when you use the phrase: 'from the perspective of both', you need to be more specific about what reference frame(s?) you're talking about there. The Twins Paradox description was a purely hypothetical thought experiment where the practicality of viewing 'from the perspective of both' was irrelevant ... but in the real universe, where real measurements are being made to test the theory ... it simply isn't achievable .. unless those practicalities are taken into account and spelled out clearly in order to avoid miscommunications (and thereby; misunderstandings).

PS: I get that you're attempting to describe proper time .. but there's a term for that, ie: 'the proper time'.

 

[Neogaia777]

Let's just stick with standard descriptions of the Twins Paradox, eh?

I mean, when you use the phrase: 'from the perspective of both', you need to be more specific about what reference frame(s?) you're talking about there. The Twins Paradox description was a purely hypothetical thought experiment where the practicality of viewing 'from the perspective of both' was irrelevant ... but in the real universe, where real measurements are being made to test the theory ... it simply isn't achievable .. unless those practicalities are taken into account and spelled out clearly in order to avoid miscommunications (and thereby; misunderstandings).

PS: I get that you're attempting to describe proper time .. but there's a term for that, ie: 'the proper time'.

Doesn't the Twin Paradox claim that one will have aged less? Or I might be thinking of something else maybe? (I might have to Google it again?)

 

[Neogaia777]

Let's just stick with standard descriptions of the Twins Paradox, eh?

I mean, when you use the phrase: 'from the perspective of both', you need to be more specific about what reference frame(s?) you're talking about there. The Twins Paradox description was a purely hypothetical thought experiment where the practicality of viewing 'from the perspective of both' was irrelevant ... but in the real universe, where real measurements are being made to test the theory ... it simply isn't achievable .. unless those practicalities are taken into account and spelled out clearly in order to avoid miscommunications (and thereby; misunderstandings).

PS: I get that you're attempting to describe proper time .. but there's a term for that, ie: 'the proper time'.

Perspective of both, I was talking about each one each individually in their own reference frames.

 

[SelfSim]

Doesn't the Twin Paradox claim that one will have aged less? Or I might be thinking of something else maybe? (I might have to Google it again?)

Its not a crime to do some research of your own before posting .. y'know(?)

 

[Neogaia777]

Its not a crime to do some research of your own before posting .. y'know(?)

If that's a nice way of you saying.I should maybe take a break, and maybe do a bit more googling before responding or replying back right now, maybe you are right, I probably should, etc. I'm out and about right now anyway, so I'll catch up with you more later, k.

Take Care