Time Dilation and the Speed of Light

[timewerx]

You guys realize you're drudging through concepts written of in SF decades ago, right?

Isaac Asimov
Robert Heinlein
Larry Niven
Jack Haldeman
Jerry Pournelle
et cetera

Yes because not everyone knows about it. Many are not even aware of these concepts. Not many are tuned in to either science or SF.

 

[Radrook]

Oh yeah, there are some good arguments why it might not work, or might work just something interesting to think about.

True!

 

[Radrook]

, hunts heads

Yes because not everyone knows about it. Many are not even aware of these concepts. Not many are tuned in to either science or SF.

Hard to imagine how anyone raised in our modern society can be totally ignorant of the time dilation in relation to the speed of light or feel that he is innovating by mentioning it in a sci-fi short story.

Maybe if a person is raised in the Amazon jungle, roams around in a loin cloth, uses a blow-gun with poisoned-tipped thorns, hunts for heads and shrinks them while chillingly chanting magical incantations through double a wooden lip plates?

 

[timewerx]

Hard to imagine how anyone raised in our modern society can be totally ignorant of the time dilation in relation to the speed of light or feel that he is innovating by mentioning it in a sci-fi short story.

You're not serious are you? You'll be surprised!

 

[Radrook]

You're not serious are you? You'll be surprised!

I guess my expectations might be a little too high. Especially here in the USA?

 

[Radrook]

Instead of speed, I've always liked the idea of just "folding space". However, it requires a lot of spice!

Then there is that little problem with the Harkonians.

 

[Radrook]

There is an interesting fact about time dilation that is truly mind-boggling.

The furthest known galaxy (as of March 2016) goes by the name of GN-z11. It’s around 13.4 billion light years away (13,400,000,000 light years). An interesting point to note is that while the light we see it by started off on its journey over 13 billion years ago that’s as measured by our Earth-bound clocks,... from the perspective of the light itself, it got here instantly and travelled zero distance in doing so. ’
Time Dilation

 

[Radrook]

Spoiler Warning!

(Just kidding. No one has to put spoiler warnings on 50 year old movies.)

Revealing that they landed on a planet of apes would' be a spoiler for either version since the title tells us that's where they are going anyway. That would be like saying that revealing that there is an alien in the film Alien is a spoiler.

Neither does the film being 50 years old avoid someone from spoiling it by revealing the ending since there are films in that age range which millions of people haven't seen and giving away the ending would indeed spoil it for them.

In fact, I once commented on the western Comanche, gave away too much and was told that I had spoiled it for the person who had wanted to see it. That film is older than Planet of the Apes. I was also recently accused of spoiling the film Burnt Offerings by provide too much detail. That one is approx. 35 years old.

 

[Justatruthseeker]

Time Dilation

The fascinating thing about traveling at close to the speed of light is time dilation-the experiencing of time at a slower rate for those on board than for those remaining back on Earth.

For example let’s consider the ratio of Earth time to ship time if we travel at 99% light speed.

At that rate it has been estimated that each day on our ship would equal a year on Earth. So a trip to our closest star system, the Alpha Centaury, which is approx four light-years distant, would be experienced as merely four days on our ship but as four years back on Earth.

Of course this isn’t factoring in the acceleration and deceleration times that such a trip would require in order to gradually build up momentum. So the crew would not experience such a drastic time dilation effect uniformly throughout the voyage. Only as the acceleration increases would the time discrepancy become more severe and the time dilation or stretching on our ship become enormous.

In any case, lets say that in our trip to the Alpha Centari system our ship takes a day for accelerate and another to gradually decelerate. That still leaves us with two ship days of time dilation at 99% speed of light on our trip to the alpha centaury system. That means that while the crew experiences two days Earth experiences two years during that same period of time. Which is neat for the crew since it significantly reduces the severe psychological stress that long duration space travel entails.

A farther destination:

For farther destinations things get a bit more creepy. For example, if the destination is 365 light years distant, then at the rate of a ship day for each Earth a year, we would reach the place in one ship year. Unfortunately, that would amount to approx 365 years on Earth.

Upon arrival, perhaps a regular year might be spent exploring the region. But with an additional ship year added in the return trip, it would increase the total round trip to approx 730 Earth years. That is similar to a person from the year 1287, 205 years before Columbus traveled to the Americas, suddenly being transported to our present time of 2017 after traveling for two years..


Other Consequences:

Of course such a phenomenon would increase the human ability to reach distant places in the cosmos via the lifespan extension. People back on Earth would be born and would die over and over as we calmly would remain untouched. Traveling at 99% the speed of light and aging only a day for every earth yea would have us age only a year for the 365 years back on earth.

But it does have a certain rather bitter downside. It requires the crew to be willing to sacrifice all relationships and the hopes of returning to the familiar Earth they left behind since many a drastic unpleasant thing can happen politically and environmentally during 730 years.


One Religious Perspective:

One sci fi film, starring Charlton Heston had the Earth overrun with apes upon their return.

Of course believers in the biblical promises would never expect such an eventuality. What they would expect would be to find Earth transformed into a global paradise instead as Bible prophecies indicate.

Other Consequences:

So lets assume the person on board the ship were to start from a stationary frame (remember, earth is traveling at an unknown velocity through space already).

1) So as he accelerates up until he reaches his top speed his clocks are continuing to slow, and he is continuing to decay slower, yes?

2) This means that in his past, his clocks ticked faster, and he decayed faster, yes?

3) So if he attempted to calculate his true age using the rate his clocks ticked while at top velocity, and assuming his decay rate was constant, he would get the wrong answer, yes?

4) To get the correct answer would require that he apply time dilation for when his clocks and decay rate occurred faster in the past, yes?

5) And if on board he had a radioactive sample, if he assumed the decay had always been the same, but in reality it was faster in the past, he would incorrectly assume vast periods of time as the sample would have decayed faster in the past, but he would be using what he believes to be the slower rate now as the constant, yes?

 

[Radrook]

Other Consequences:

So lets assume the person on board the ship were to start from a stationary frame (remember, earth is traveling at an unknown velocity through space already).

1) So as he accelerates up until he reaches his top speed his clocks are continuing to slow, and he is continuing to decay slower, yes?

2) This means that in his past, his clocks ticked faster, and he decayed faster, yes?

3) So if he attempted to calculate his true age using the rate his clocks ticked while at top velocity, and assuming his decay rate was constant, he would get the wrong answer, yes?

4) To get the correct answer would require that he apply time dilation for when his clocks and decay rate occurred faster in the past, yes?

5) And if on board he had a radioactive sample, if he assumed the decay had always been the same, but in reality it was faster in the past, he would incorrectly assume vast periods of time as the sample would have decayed faster in the past, but he would be using what he believes to be the slower rate now as the constant, yes?

Using the radioactive sample of something that had decayed faster in the past would give him an incorrect reading if he assumed that the rate had been constant. So yes I agree the same applies to all the other scenarios you describe which are essentially him making the same mistake but with the clocks.

However, true age as it would be counted by Earth time vs true age as counted by ship time are both legitimate ages. A person on board the ship might say that he is twenty years old after leaving Earth and the persons he left behind might have died of old age. But that doesn't mean that he isn't really twenty years old relatively speaking. What it means is that he isn't twenty Earth- years old, right?

 

[Justatruthseeker]

Using the radioactive sample of something that had decayed faster in the past would give him an incorrect reading if he assumed that the rate had been constant. So yes I agree the same applies to all the other scenarios you describe which are essentially him making the same mistake but with the clocks.

However, true age as it would be counted by Earth time vs true age as counted by ship time are both legitimate ages. A person on board the ship might say that he is twenty years old after leaving Earth and the persons he left behind might have died of old age. But that doesn't mean that he isn't really twenty years old relatively speaking. What it means is that he isn't twenty Earth- years old, right?

But since God "stretched out the heavens", and the local galactic group accelerated at an unknown rate for an unknown period to reach its present unknown velocity, dont you think time dilation needs applied for the earth as well? I mean it didnt get to its present unknown velocity without accelerating, yes? So what does that say about the radioactive samples on this rocket ship we call earth, not just the other rocket ship??

But the person in motion cant tell his clocks are slowing, and actually believes earth clocks are slowing, even if he is the one increasing in acceleration. So his clocks cant be relied upon to give a true accounting once he leaves this frame. Just as once the earth began accelerating........

Edit: So wouldn't the radioactive samples on earth assuming the constant of today when it was faster in the past, also provide incorrect answers?

 

[Radrook]

But since God "stretched out the heavens", and the local galactic group accelerated at an unknown velocity for an unknown period to reach its present unknown velocity, dont you think time dilation needs applied for the earth as well? I mean it didnt get to its present unknown velocity without accelerating, yes? So what does that say about the radioactive samples on this rocket ship we call earth, not just the other rocket ship??

I imagined that you were leading up to the age of the earth and how it could be misinterpreted.
That is a very interesting point. Why indeed would Earth or any other celestial body be totally impervious to time dilation induced by velocity? I personally see no reason to conclude why they should be an exception.
.
However, one very important thing that should be kept in mind about stretching out the heavens is that the stretching which cosmologists are referring to does not involve the proper motion of the objects in the universe.

It is only related to the stretching of space itself which make the galactic super clusters appear to be traveling close to the speed of light and are assumed to be distancing themselves from us at that velocity due the constant addition of distance or space and not because of their proper motion through space itself.

Indeed if it were proper motion then we would need to conclude that galaxies beyond our detection are breaking the speed of light limit. But that isn't the case. What is being added faster than light is the space between the galactic super clusters and causing what we detect as great voids.

So if indeed time dilation took place, which I am sure it has, we cannot attribute it to proper motion through space at the rate that the stretching seems to indicate. Which means of course that we would need to refrain from using the great velocities attributed to the expansion of the universe in reference to it as applicable to our Earth. Otherwise, if the current models of universal expansion is true, then we fall into the same pitfall as our hypothetical space traveler who uses improper criteria to determine his age.

However, if the current idea isn't true, then the time dilation via proper motion through space comes into play with far more force.

 

[essentialsaltes]

Revealing that they landed on a planet of apes would[n't] be a spoiler for either version since the title tells us that's where they are going anyway.

What I was referring to was when you wrote: "had the Earth overrun with apes"

 

[FrumiousBandersnatch]

... lets assume the person on board the ship were to start from a stationary frame (remember, earth is traveling at an unknown velocity through space already).

There is no universal stationary frame. Everything is moving with respect to something else. Einstein's legacy is relativity. All that matters is that you specify how the particular objects you're interested in are moving relative to each other. If they're not moving relative to each other, each is stationary in the other's frame of reference.

1) So as he accelerates up until he reaches his top speed his clocks are continuing to slow, and he is continuing to decay slower, yes?

His clocks only tick slower as measured from a frame he's moving relative to (e.g. Earth).

2) This means that in his past, his clocks ticked faster, and he decayed faster, yes?

Relative to some other frame of motion.

3) So if he attempted to calculate his true age using the rate his clocks ticked while at top velocity, and assuming his decay rate was constant, he would get the wrong answer, yes?

If he measures time by his own clocks, he will always see his time running at a constant rate - that should be obvious; the clocks measure the time he and everything moving with him experiences. For him, his age is the elapsed time he has experienced (as measured by his clocks). For someone in relative motion to him, it would be different. There is no 'true' age, just as there is no universal stationary frame, and no absolute simultaneity; I suppose you could say his 'true' age is his age as he measures it, but that ignores the rest of the universe.

4) To get the correct answer would require that he apply time dilation for when his clocks and decay rate occurred faster in the past, yes?

Only if he wanted to get his age as calculated by someone in relative motion to him (e.g. on Earth).

5) And if on board he had a radioactive sample, if he assumed the decay had always been the same, but in reality it was faster in the past, he would incorrectly assume vast periods of time as the sample would have decayed faster in the past, but he would be using what he believes to be the slower rate now as the constant, yes?

There is no absolute measure of time; it varies with relative motion (and the influence of gravity). For him, it would be constant (he'd see other's time faster or slower depending on their motion relative to him). For others his time might have flowed faster in the past or slower in the past, depending on their relative motion.

 

[FrumiousBandersnatch]

But since God "stretched out the heavens", and the local galactic group accelerated at an unknown rate for an unknown period to reach its present unknown velocity...

Since the accelerating expansion of the universe is spacetime itself expanding, the galaxies are not undergoing relativistic acceleration (which also means their separation velocity can exceed light speed), so they don't undergo relativistic time dilation, only a Doppler effect time dilation (as when a siren has a higher frequency when approaching and a lower frequency when going away).

 

[jacks]

To be perfectly honest, I'm not even sure what "time" is. Does it exist or is it just a handy way to think about things?

 

[Radrook]

To be perfectly honest, I'm not even sure what "time" is. Does it exist or is it just a handy way to think about things?

Whether or not time itself is a tangible existing thing apart from the human mind or is merely a judgment based on perceptions of sequences of events, going from the past through the present to the future is a matter of debate.

Remove the presence of a perceiving mind and what remains? That is the real question since our reality as perceived is a mere an interpretation of our senses and what remains when human senses aren’t involved remains a mystery.

Time - Wikipedia

 

[Justatruthseeker]

I imagined that you were leading up to the age of the earth and how it could be misinterpreted.
That is a very interesting point. Why indeed would Earth or any other celestial body be totally impervious to time dilation induced by velocity? I personally see no reason to conclude why they should be an exception.
.
However, one very important thing that should be kept in mind about stretching out the heavens is that the stretching which cosmologists are referring to does not involve the proper motion of the objects in the universe.

Yes, I know, they have objects in the universe magically increasing in distance away from one another but not increasing in actual velocity

Simply their excuse to keep belief in cosmological redshift alive after technology falsified their belief, so the changed it to magical expanding nothing.

It is only related to the stretching of space itself which make the galactic super clusters appear to be traveling close to the speed of light and are assumed to be distancing themselves from us at that velocity due the constant addition of distance or space and not because of their proper motion through space itself.

And yet a boat on a river that was increasing in speed, would still be accelerating, even if it was motionless in relation to the water itself. So if cosmological redshift does not equal velocity and distance, then their is no reason to assume those galaxies are at the claimed distance based on redshift values, now is there? I'm sorry, but they can't have it both ways.....

Indeed if it were proper motion then we would need to conclude that galaxies beyond our detection are breaking the speed of light limit. But that isn't the case. What is being added faster than light is the space between the galactic super clusters and causing what we detect as great voids.

Or that they simply refused to look for another cause once technology falsified their belief that redshift was velocity and distance before they changed it to magical expanding nothing?

I see no reason to accept ad hoc theory when actual physics will do.

A New Non-Doppler Redshift

So if indeed time dilation took place, which I am sure it has, we cannot attribute it to proper motion through space at the rate that the stretching seems to indicate. Which means of course that we would need to refrain from using the great velocities attributed to the expansion of the universe in reference to it as applicable to our Earth. Otherwise, if the current models of universal expansion is true, then we fall into the same pitfall as our hypothetical space traveler who uses improper criteria to determine his age.

However, if the current idea isn't true, then the time dilation via proper motion through space comes into play with far more force.

And yet I refuse to believe in magic expansion of nothing. They want galaxies to be increasing in distance at an accelerating rate, but not increasing in velocity. Unless you can show me the expansion of space in a laboratory, I see no reason to accept magical expanding nothing that would violate every known physical law including conservation of energy. Not only must energy be increasing, but nothing (space) must be being created as well. I don't buy into their stop gap excuse of illogic, see reference above.

Ever ask yourself why 96% of their cosmology is non detectable ad hoc fluff filler to make the numbers add up?

 

[Radrook]

Yes, I know, they have objects in the universe magically increasing in distance away from one another but not increasing in actual velocity

Simply their excuse to keep belief in cosmological redshift alive after technology falsified their belief, so the changed it to magical expanding nothing.



And yet a boat on a river that was increasing in speed, would still be accelerating, even if it was motionless in relation to the water itself. So if cosmological redshift does not equal velocity and distance, then their is no reason to assume those galaxies are at the claimed distance based on redshift values, now is there? I'm sorry, but they can't have it both ways.....


Or that they simply refused to look for another cause once technology falsified their belief that redshift was velocity and distance before they changed it to magical expanding nothing?

I see no reason to accept ad hoc theory when actual physics will do.

A New Non-Doppler Redshift


And yet I refuse to believe in magic expansion of nothing. They want galaxies to be increasing in distance at an accelerating rate, but not increasing in velocity. Unless you can show me the expansion of space in a laboratory, I see no reason to accept magical expanding nothing that would violate every known physical law including conservation of energy. Not only must energy be increasing, but nothing (space) must be being created as well. I don't buy into their stop gap excuse of illogic, see reference above.

Ever ask yourself why 96% of their cosmology is non detectable ad hoc fluff filler to make the numbers add up?

I agree, it does sound a bit funny. That's why I added "If it is true...." at the end.

 

[FrumiousBandersnatch]

To be perfectly honest, I'm not even sure what "time" is. Does it exist or is it just a handy way to think about things?

A very good question - I went to a talk last week by Dean Buonomano on the 'Neuroscience and Physics of Time' in London, and came away with a lot of hypotheses about it, but more questions than answers. Eternalism (4D block universe) or Presentism (only 'now' exists), or something else?

I asked him whether the difficulty was more a semantic and conceptual one than a physical one - he agreed that there's a sense in which we're too embedded in it to be objective or find the concepts intuitive.