Time Travel is Science Fiction

[paddoboy]

Strange as it may seem, not everything on TV, the movies and comic books is true. In fact, the main reason this thread is so long and full of controversy is that time travel was depicted on TV and hence many people take it as gospel truth. Would old H.G. Wells late-night TV and Michael J. Fox movies lie!? Not about what general relativity does and does not forbid surely! That would be sacrosanct!

Strange as it may seem, the Universe on a whole, does not always adhere to the "intuitive" nature and outlook we will always perceive on planet earth. eg: Non absolute nature of space and time....time dilation and length contraction plus the fact that all FoR's are as valid as each other....BH's....DM....DE.

The Universe is a weird and wonderful place, and one must go where the observational and experimental data tells him, and forget intuition.

No, you don't get it.

The reason this thread is so long is because of people who don't want to address the hard parts of the science and just dismiss it on prejudice. Or, in the case of Farsight, who want to use the rejection of time travel as evidence that their own pseudo-theories are correct.

Time travel is an element of science fiction. It is not likely that we can actually do anything like that fiction. Yet many physicists have outlined plausible scenarios where something similar to time travel is possible and there is no definitive argument against these scenarios.

Yep, just as all the links and tashja's experts have said!

 

[Billy T]

The reason the satellite clock tick rate is faster than the earth clock tick rate is the gravitational time dilation component is > the SR [relative velocity] component. ...

I of course agree. Said exactly the same. Quoting from first line of post 1263:
"the slowing of the earth based clock by stronger gravity dominates the satellite speed's slowing."

I did not make the effort to follow your math, but assume it confirms that gravity dominates - makes more slowing of clock on Earth than the orbital speed slows the clock in orbit. Is that what your math shows for the GPS clock orbit?

There surely must be a higher altitude orbit where the earth clock and the orbiting clock run at the same rate as we gravity falls off rapidly (in verse square) with distance. That I the orbit I called a second geostationary orbit - one where equal clock rates occur. Not one where the orbit period is 24 hours in the standard "geostationary orbit."

Can you "twist" your math to find that second geostationary orbit? Below it orbiting clocks run faster than earth clocks. Above it orbiting clocks run slower than earth clocks.

I probably am not the first to recognize this second type of geostationary orbit exist. I am not good at searching - perhaps some one has already calculated it. I bet clocks on some planet's most distant small moons do run slower than earth's clocks. Surely Pluto's tiny moon, Charon's clocks do run slower than Earth's do. What do you think - Are they "time traveling" or just aging more slowly?

 

[Sylvester]

paddoboy, so why dont you tell us how you travel back in time?
What are you going to get in a space ship and travel real fast in the upper atmosphere and go back to 1959? Not happening pal.

 

[paddoboy]

paddoboy#1225
I don't see you as arrogant, maybe just opinionated.
People may see me as such, but if they can prove me wrong based on some evidence, I'll change.

In actual fact, there are may opinionated posters here and they have taken two opposite sides and opposing views. Am I one? I don't believe so, and I also believe those holding the contrary view to mine, have taken this whole debate beyond the simple statements that.....
GR and the laws of physics do not forbid time travel, and in fact give possible solutions to how that can be achieved:
Any sufficiently advanced civilisation could achieve it:

This is your gloom and doom conclusion, based on what, other than your life experiences.
D0n't you think the problems of the world can be solved?

The point of the fly scenario is perspective. If they had lived longer, they could have reconciled the differences in their interpretation of their world.

That is not true. I'm an optimist and always have been. When I said.....
"And in all reality, if we don't achieve all those possibilities, along with inter-stellar travel, then we are doomed as a species.
In summing, we were not born to stagnate on this fart arse little blue orb"
I was referring to the inevitable use by date of the Sun and the Earth.
In other words I was being optimistic enough to perceive the human race as still being around in about 3 to 4 billion years, when the Sun becomes a red giant, and life on Earth will be impossible.
If we havn't moved beyond our solar system by then, then yes, we are doomed.

The marvelous human mind, is not going to understand the complex universe after two centuries of concentrated scientific study. Knowledge is a continuous process of refinement. There are still more questions than answers.

Agreed. Did I say or infer any different?

To me it's foolishness to predict a long term outcome based on short term limited information.
Long term predictions assume a trend will continue, without any intervening phenomena, and are based more on ignorance than fact.

I wasn't predicting as much as just saying that what is not forbidden by the laws of physics and GR could be obtainable, given that all important ingrediant called time.
We have about 3 billion years to progress to the technology of interstellar travel.
If we are able to do that, we may survive as a species beyond 3 billion years.
First though, we need to survive our own planetary Earthly follies to get to that period, but I believe we will do it.

 

[paddoboy]

paddoboy, so why dont you tell us how you travel back in time?
What are you going to get in a space ship and travel real fast in the upper atmosphere and go back to 1959? Not happening pal.

The methodologies have been given many times. At this stage we do not have the technology to do it, also said many times, and the possibility exists that it may never be done. We only have theoretical applications as to how it maybe achieved.
But that isn't what's being debated here.
What you are asking me to do is akin to asking Captain James Cook, to fly from England to Australia in 1770

 

[Sylvester]

Its not possible. Organic substances are related to TIME. That trumps everything else. Organic substances will NOT be the same as they were.

 

[paddoboy]

Its not possible. Organic substances are related to TIME. That trumps everything else. Organic substances will NOT be the same as they were.

Don't argue with me. You take it up with all those in mainstream cosmology, including Thorne, Sagan, Smolin, Carroll, Kaku, Paul Davis, and the many professional links given in this and the other time thread.

 

[krash661]

Not happening pal.

neither is the intelligence you wish to achieve or think you have achieved.

 

[Trippy]

Surely Pluto's tiny moon, Charon's clocks do run slower than Earth's do. What do you think - Are they "time traveling" or just aging more slowly?

You've already been given an answer to this question, however, you chose to ignore it.

 

[Billy T]

If you add up the accumulated speed cosmonaut Sergei Krivalev has traveled in space – the most of any human with a total time spent in orbit of 803 days 9 hours and 39 minutes – he has actually time-traveled into his own future by 0.02 seconds.

To show how silly it is IN PRINCIPLE to call 0.02 of slower aging "time travel" I will assume: Other guy in photo is Ivan Krivalev, Cosmonaut Sergei's identical twin brother. (Note "identical twin" means they were once a single fertilized egg - i.e. began life at exactly the same time.)

Ivan was at the launch and then 803 days later, went to the landing site, by bus, to greet his returning brother, who indeed was now 0.02 seconds younger than Ivan was. Some silly people think Sergei "time traveled" yet Sergie & Ivan were hugging each other at exactly the same time 804 days after launch - started life at the same instant and embraced each other at the same instant about 804 days post launch. If one "time traveled" by space craft to the "embrace instant" so did the other, but Ivan got to that location AND TIME by bus!

The truth is neither "time traveled" but also true is that Sergie did age less during his earth orbiting than Ivan did by 0.02 seconds.

If instead of just orbiting Earth, Sergei had done the standard "twin paradox" trip, starting when both twins were 30 years old, then when he returned to Earth, in the prime of his life (40 years old) Sergie could be embracing Ivan, a 70 years old man. I.e. while Sergei spent 10 years traveling in a rocket ship Ivan spent 40 years on earth waiting for his brother to return. None-the less there they were, embracing in the same minute that was 40 years after the launch of the rocket.

Clearly, what has happened is Sergei aged at only 25% of the rate Ivan did, but did not travel any farther into the future as there they are embracing 40 years after the launch. The principle is the same for being 0.02 seconds or being 30 years younger than your twin. It is not "time travel" it is "slower rate of aging."

 

[Sylvester]

Don't argue with me. You take it up with all those in mainstream cosmology, including Thorne, Sagan, Smolin, Carroll, Kaku, Paul Davis, and the many professional links given in this and the other time thread.

They can come here and debate me. Why dont you send them an email?

 

[brucep]

I of course agree. Said exactly the same. Quoting from first line of post 1263:
"the slowing of the earth based clock by stronger gravity dominates the satellite speed's slowing."

I did not make the effort to follow your math, but assume it confirms that gravity dominates - makes more slowing of clock on Earth than the orbital speed slows the clock in orbit. Is that what your math shows for the GPS clock orbit?

There surely must be a higher altitude orbit where the earth clock and the orbiting clock run at the same rate as we gravity falls off rapidly (in verse square) with distance. That I the orbit I called a second geostationary orbit - one where equal clock rates occur. Not one where the orbit period is 24 hours in the standard "geostationary orbit."

Can you "twist" your math to find that second geostationary orbit? Below it orbiting clocks run faster than earth clocks. Above it orbiting clocks run slower than earth clocks.

I probably am not the first to recognize this second type of geostationary orbit exist. I am not good at searching - perhaps some one has already calculated it. I bet clocks on some planet's most distant small moons do run slower than earth's clocks. Surely Pluto's tiny moon, Charon's clocks do run slower than Earth's do. What do you think - Are they "time traveling" or just aging more slowly?

We could figure out the tick ratio between a clock in Charons local proper frame and a clock in our local proper frame at the surface of the earth. This is how it goes according to GR. The delta tick ratio is probably going to be an infinitesimal [as is the GPS] for most all local proper frames in the weak field which is most everywhere in the universe. You'll be able to get that after I'm done with this very simple calculation [most GR analysis is pretty simple being one of the reasons folks comment on how elegant the theory is]. To see where this comes from review the box on page 2-31 on chapter 2 Curving at the download I linked for the project on the GPS.

In geometric units
M_earth = .00444 meter
r_shell earth surface = 6.371E6 meter

M_Pluto = .000009689 meter
r_shell Charon = 17,536,000 meter

dt_shell earth / dt_shell_charon = (1-2M_earth/r_shell earth surface)^1/2 / (1-2M_pluto/r_shell Charon)^1/2

= .999999999/1 the local proper frame tick rates are equivalent to < a nanosecond per second. That's pretty much what you'll find when comparing weak field local proper frame tick rates. The strong field begins when comparing the near sun spacetime with with weak field objects like the earth. Culminating with comparisons with near black hole space times. That's pretty much how you would calculate the worm hole thought experiment that Prof Thorne was discussing. Compare the local proper frame tick rate at the mouth of the wormhole to the local proper frame tick rate at the egress of the wormhole. The only reason a discussion like this can be scientific is because Einstein made it happen when he derived his LOCAL theory of gravity.
BTW the SR. component associated with relative velocity is irrelevant due to obvious reasons for this analysis. The reason we bother for the GPS is the signals travel at c which is approximately 1/3 meter per nanosecond. So for every nanosecond deviation the signal will be off ~ 1/3 meter.

 

[LaurieAG]

To compare GR and its predictive equations to "flying pigs" is pretty silly and naive in the extreme.

Sending light pulses through a wormhole isn't exactly time travel either.

 

[PhysBang]

To show how silly it is IN PRINCIPLE to call 0.02 of slower aging "time travel"

It is silly.

However, only you (and perhaps some cranks I have yet to come across) are calling this "slower aging". There is a big difference between the change of a rate of certain processes (e.g., biological processes) and the change of all possible physical processes in a coordinated fashion.

Some silly people think Sergei "time traveled" yet Sergie & Ivan were hugging each other at exactly the same time 804 days after launch - started life at the same instant and embraced each other at the same instant about 804 days post launch. If one "time traveled" by space craft to the "embrace instant" so did the other, but Ivan got to that location AND TIME by bus!

The above is foolishness: one expects that time travelers, should they exist, will end up at some place and time. So that someone is present at an event is not evidence that they did not time travel.

The truth is neither "time traveled" but also true is that Sergie did age less during his earth orbiting than Ivan did by 0.02 seconds.

Neither of those is true. Sergie literally experienced a different amount of time, he did not merely age less in the same amount of time.

Unless one wants to adopt peculiar relativity (like Farsight) where there is an absolute reference frame with the real speed of light and the real measurements of objects and all other frames are merely distortions. (Bell also developed this idea, but with some actual rigor and without many of the conceptual mistakes Farsight introduces.)

 

[paddoboy]

Sending light pulses through a wormhole isn't exactly time travel either.

It's theoretically applicable from the GR equations...Flying pigs are not.

 

[paddoboy]

They can come here and debate me. Why dont you send them an email?

A number have already given their views and in all cases, they all agree that time travel is not forbidden by the laws of physics and GR, and GR gives possible solutions also.
If you disagree with that, then let's see you show evidence that GR equations are totally wrong, before I ever go to the trouble of bringing anyone with professional expertise on this subject, to debate with amateurs, with all due respect of course.

 

[Billy T]

... one expects that time travelers, should they exist, will end up at some place and time. So that someone is present at an event is not evidence that they did not time travel. ...

Nor was that "Other people are there." offered as proof that it was silly to say Sergei is a "time traveler."
What made that claim silly was that his identical twin brother, Ivan, arrived at that the same time and place by bus, not by space craft.

I agree, that Sergei could have made a standard twin paradox trip that aged him 10 years, to age 40, while on Earth Ivan aged 40 years to become 70 years old.

It is silly to claim that only one of the twins who began life as a single egg (at precisely the same time and place) and then years later embrace at precisely the same time and place did "time travel" and the other one did not. It makes more sense IF you must insist some "time travel" was done to say Sergei traveled BACKWARDS in time to the era that he and Ivan were both 40 years old.

For those who did not read post 1290 (photo of cosmonaut Sergei there) here is link: http://www.sciforums.com/threads/time-travel-is-science-fiction.140847/page-65#post-3251637

SUMMARY: My argument is semantic. I just think it silly (certainly inconsistent) to say only one of two twins would shook hands just before one got into his space suit and was there later to embrace him when he returned to earth was a "time traveler." Both were together at same time and place at start of the space trip and together at the same time and place when the trip was over.

I accept SR's time dilation. In fact 10 years ago posted supporting evidence that it is very real. I.e. the cosmic ray "daughter" muons have very short half life so even at the speed of light, they could not get down to the surface of the earth from the very high altitude were the primary ray created them unless time dilation (and space contraction)* are real.

* In their rest frame half of them "die right on schedule" but they "see" our 100,000 meter thick atmosphere as contracted to only a few hundred meters thick, so most make it to the surface, before they die (decay). What we see as "time dilation" the muon "see" as "space contraction." These are just the "two sides" of SR coin.

 

[paddoboy]

I accept SR's time dilation. In fact 10 years ago posted supporting evidence that it is very real. I.e. the cosmic ray "daughter" muons have very short half life so even at the speed of light, they could not get down to the surface of the earth from the very high altitude were the primary ray created them unless time dilation (and space contraction)* are real.

* In their rest frame half of them "die right on schedule" but they "see" our 100,000 meter thick atmosphere as contracted to on a few hundred meters thick, so most make it to the surface, before they die (decay). What we see as "time dilation" the muon "see" as "space contraction." These are just the "two sides" of SR coin.

Well I'm not sure they'll award you a medal for that, considering it has been two well verified facts of relativity for quite a while now.
I mean, really, there is no reason [considering the observational data] for anyone to disbelieve it.

On the twin paradox, which isn't a paradox anyway, the travelling twin arrives back on Earth 230 years into the future...because he has aged slower, but that slower aging, has been the cause of him missing 229 Earth years, and all the changes that has occurred in that 229 years, [while he has aged 12 months] including the long dead and buried twin he left behind.
I don't understand why anyone does not see that as a form of time travel.

 

[PhysBang]

Nor was that "Other people are there." offered as proof that it was silly to say Sergei is a "time traveler."
What made that claim silly was that his identical twin brother, Ivan, arrived at that the same time and place by bus, not by space craft.

Yes, and it is equally as useless to point out that people can arrive at the same event (or at adjacent events) by different means.

Your reasoning is not getting any better.

It is silly to claim that only one of the twins who began life as a single egg (at precisely the same time and place) and then years later embrace at precisely the same time and place did "time travel" and the other one did not. It makes more sense IF you must insist some "time travel" was done to say Sergei traveled BACKWARDS in time to the era that he and Ivan were both 40 years old.

I do not think that calling time dilation time travel is useful. It is, however, far more useful and correct than calling it the slowing of the aging process.

SUMMARY: My argument is semantic. I just think it silly (certainly inconsistent) to say only one of two twins would shook hands just before one got into his space suit and was there later to embrace him when he returned to earth was a "time traveler." Both were together at same time and place at start of the space trip and together at the same time and place when the trip was over.

That is, again, not a good argument. If someone wrote a science fiction story where one twin got into a device and immediately met his or her twin twenty years in the future, it would not do to argue that it was not a time travel story because the twins met again.

In the case of time dilation, there is a different amount of time on different paths to the same event. So while it is much less interesting "time travel" than what one expects from science fiction, it certainly highlights that time behaves differently according to SR than our ordinary understanding.

I accept SR's time dilation.

You seem to do so selectively, but let's accept that you do.

 

[Motor Daddy]

On the twin paradox, which isn't a paradox anyway, the travelling twin arrives back on Earth 230 years into the future...

So he left in 1600 and returns in 1830.

because he has aged slower, but that slower aging, has been the cause of him missing 229 Earth years,

So he missed 229 earth years, from 1600-1829.

and all the changes that has occurred in that 229 years, [while he has aged 12 months] including the long dead and buried twin he left behind.

When did the long dead twin die, 1601?

I don't understand why anyone does not see that as a form of time travel.

Help me out here and we'll find out.