Time traveling

[JesterFace]

”Traveling” in time is possible to the future with a massive gravity source, but...

If timetraveling was possible backwards in time, wouldn't we have already seen visitors from the future?

My own assumption is that there is no past of future to travel to, present is the only place to exist.

 

[Metryq]

”Traveling” in time is possible to the future with a massive gravity source,

What makes you think time is slowing down in a gravitational field and not merely atomic processes? Does time slow down when you press a finger into the movement of a clock? Don't reify mental constructs.

If timetraveling was possible backwards in time, wouldn't we have already seen visitors from the future?

Proving a negative didn't work for the Fermi paradox, and it doesn't work here.

My own assumption is that there is no past of future to travel to, present is the only place to exist.

First sensible thing you said in this post.

 

[Asbo Zaprudder]

I can travel into the future at an average rate of one second per second although if I'm standing up my head is ageing more rapidly than my feet.

http://www.nist.gov/pml/div688/clocks_092810.cfm

 

[JesterFace]

What makes you think time is slowing down in a gravitational field and not merely atomic processes?

I'm simply basing this on documentaries on TV...

 

[JesterFace]

Proving a negative didn't work for the Fermi paradox, and it doesn't work here.

The universe is still quite young... and big.

 

[Ronald Held]

Time dilation in SR is a way to travel into the future.

 

[JesterFace]

SR?

 

[B.J.]

^Special Relativity

 

[HIjol]

I absolutely believe time travel is possible. We have evidence that subatomic particles and atoms can do it, and it is likely only a matter of time before we figured out how to do it with larger quantities of mass. Eventually, we will build our own time machine, go back or forward, change the slightest bit of past or future, and then, like
"Millennium", "Back to the Future's" and nu"Apes", cause a time ripple or tear or discontinuity or what have you, have it cascade through "our" spacetime, and destroy Everything. Maybe that partly explains the posited existence of infinite universes and such. Civilizations keep destroying them with time travel, and the "unravel/'re-ravel' (if you will) continues in an infinite cycle.

Wow! Only two cups of coffee!

HIjol, Dude!
I know, man, I know!...

But I do believe that could be true!

 

[Skellington]

^ One thing that concerns me is that the (presumed) non-existence of civilisation elsewhere in the universe means that apparently no-one else has tried backwards time travel, in which case our first foray would be a singular event for the universe, with no experimental evidence that the causal nexus could accommodate it.

 

[HIjol]

^ One thing that concerns me is that the (presumed) non-existence of civilisation elsewhere in the universe means that apparently no-one else has tried backwards time travel, in which case our first foray would be a singular event for the universe, with no experimental evidence that the causal nexus could accommodate it.

I like your theoretical thinking, but, perhaps the singular event would only be for this Universe, thereby only destroying our perception and experience of "reality?, if that makes sense.

Similarly, you are absolutely correct as to the '...no experimental evidence..." (In the words of Sarah Conner, "They (we) cannot make (do) things like that yet.") so, again, the causal nexus you speak of may only be operative for the "reality" and Universe we perceive.

(Wow, reread sounds like Doc Brown on amphetimines!)

But it is making sense in my brain!

 

[Silvercrest]

I can travel into the future at an average rate of one second per second although if I'm standing up my head is ageing more rapidly than my feet.

http://www.nist.gov/pml/div688/clocks_092810.cfm

That explains why the hair on my head is turning grey faster than the rest.

 

[Crazy Eddie]

”Traveling” in time is possible to the future with a massive gravity source,

What makes you think time is slowing down in a gravitational field and not merely atomic processes?

1) Isn't that one of the predictions of General Relativity? That gravitational time dilation causes an inherent breaking of simultaneity between an object in strong gravity and an object outside of the gravity well? That was, in fact, a critical plot point in "Interstellar" and one of the things Stephen Hawking has been saying for years.

2) IF the effect is only atomic processes and not the actual passage of time, wouldn't it only be the OBSERVATION of those processes that's affected? I.E. the atomic clock appears to be running slower simply because gravitational distortion lengthens the wavelength of electromagnetic waves you're using to view the clock in the first place?

 

[Asbo Zaprudder]

There is no such thing as simultaneity in either Special or General Relativity. It depends on the frame of reference (FoR). The only guarantee is that causally connected events happen in the correct order although the timings can be different as seen from different FoRs. Within your FoR, you don't notice any difference in the passing of time. It's your measurement of the timing of events, whether micro or macro, in other FoRs that can differ. Moving clocks, again micro or macro, appear to tick slower as do clocks deeper in a gravity well. The effect has been experimentally verified by taking atomic clocks on plane journeys, the Mössbauer effect, pulsar observations... There is no such thing as absolute spacetime. In fact, there would be no such thing as spacetime if it weren't for the Higgs field imbuing particles such as quarks and electrons with rest mass and so preventing them from travelling at the speed of light. Passage through time or space aren't measurable for particles travelling at light speed, which have no rest frame.

 

[Nebusj]

2) IF the effect is only atomic processes and not the actual passage of time, wouldn't it only be the OBSERVATION of those processes that's affected? I.E. the atomic clock appears to be running slower simply because gravitational distortion lengthens the wavelength of electromagnetic waves you're using to view the clock in the first place?

What is the difference between the passage of time and changes in observable things?

 

[HIjol]

“Einstein said, ‘Time has no independent existence apart from the order of events by which we measure it,’”

If I am reading this very good article on the subject, there is no "...difference between the passage of time and changes in observable things." (Nebusj)


The "passage of time" defines the observable thing. In the article, an example is given of a photon moving a Planck's Distance from point 1 to point 2. There is no "time" involved, just movement (change).


This one just blew me away:


“Newton theory on absolute time is not falsifiable, you cannot prove it or disprove it, you have to believe in it,” Sorli said. “The theory of time as the fourth dimension of space is falsifiable and in our last article we prove there are strong indications that it might be wrong. On the basis of experimental data, time is what we measure with clocks: with clocks we measure the numerical order of material change, i.e., motion in space.”

A good read and pretty clear language for something difficult to Grok (at least for me!).

http://phys.org/news/2011-04-scientists-spacetime-dimension.html#jCp

 

[Crazy Eddie]

Moving clocks, again micro or macro, appear to tick slower as do clocks deeper in a gravity well. The effect has been experimentally verified by taking atomic clocks on plane journeys, the Mössbauer effect, pulsar observations... There is no such thing as absolute spacetime.

The thing is, if the effect is merely OBSERVED between differing frames of reference, then the effect should disappear when the clocks are brought bak together into the same reference frame.

In your post, you suggest this doesn't happen: a clock placed in motion or placed deeper in a gravity well will, when returned to the frame of the stationary/higher clock, no longer be simultaneous with its partner (one of them will be slightly ahead, having elapsed more time than the other).

So when Metryq asked:

What makes you think time is slowing down in a gravitational field and not merely atomic processes?

The answer is:

Moving clocks, again micro or macro, appear to tick slower as do clocks deeper in a gravity well.

If this is merely an "appearance" of an effect, then it should be apparent ONLY while one clock is deeper in the gravity well than the other one.

If this is an ACTUAL effect, then the slower clock will remain behind the faster even after they are returned to an identical frame of reference.

The implication in the latter case -- that this is an actual effect -- suggests that placing an object in extremely strong gravity would slow down the passage of time for that object to the point that it would be able to travel FAR into the future (relative to everything outside the gravity well) while experiencing very little progression of its own time.

2) IF the effect is only atomic processes and not the actual passage of time, wouldn't it only be the OBSERVATION of those processes that's affected? I.E. the atomic clock appears to be running slower simply because gravitational distortion lengthens the wavelength of electromagnetic waves you're using to view the clock in the first place?

What is the difference between the passage of time and changes in observable things?

Certain changes are known to take a consistent amount of time to occur (half lives of isotopes, for example). The passage of time is the interval over which these changes tend to take place.

 

[Asbo Zaprudder]

The twin paradox has been experimentally verified with initially synchronised atomic clocks. If you return a clock to a FoR after it's been accelerated, decelerated or placed at a different level in a gravity well, the clocks again tick at the same rate but show different times as predicted by SR and GR within experimental error.

http://math.ucr.edu/home/baez/physics/Relativity/SR/experiments.html#Twin_paradox

 

[Metryq]

Certain changes are known to take a consistent amount of time to occur (half lives of isotopes, for example).

The Sun is changing the rate of radioactive decay, and breaking the rules of chemistry

Also:
What the Global Positioning System Tells Us about Relativity

It is important to realize that none of the 11 independent experiments said to confirm the validity of SR (Special Relativity) experimentally distinguish it from LR (Lorentzian Relativity) — at least not in Einstein's favor.
...

Richard Keating was surprised in 1972 that two atomic clocks traveling in opposite directions around the world, when compared with a third that stayed at home, showed slowing that depended on their absolute speed through space -- the vector sum of the Earth's rotation and airplane speeds -- rather on the relative velocities of the clocks. But he quickly accepted that astronomers always use the Earth's frame for local phenomena, and the solar system barycentric frame for other planetary system phenomena, to get results that agreed with the predictions of relativity. Being unaware of LR, he did not question the interpretation at any deeper level.
...
Of those who have compared both LR and SR to the experiments, most seem convinced that LR more easily explains the behavior of nature.

This is just one example. There are many studies and observations that question the accuracy of Einsteinian Relativity, from GPS and simultaneity to bending of starlight.

 

[Timewalker]

If timetraveling was possible backwards in time, wouldn't we have already seen visitors from the future?

Maybe we have, and just didn't recognize them as being from the future.

Or if time travel was discovered far enough in the future, they might just consider this particular era as too boring to visit.