Time

[EvilEye]

No no no... the person standing still is still moving... but slower relative to the person going near the speed of light... who ages slower.

They meet back up after the same counted time for each and traveler has aged less. Traveler cannot age less than himself. Just less quickly that than static friend.

der..... time passes the same for each as they travel their OWN paths, but not relative to each other.... HOWEVER they are still both moving along the same "static" time.

I can ride a bike and you can drive a car. It has no effect on the how far we can go.. just on how fast we get there.

If I leave for Boston on a flight from Orlando, and you leave for Boston in a car, we will both eventually be in the same place, but NOT at the same time. AND when we are there at the same time, I will have been there longer than you. (ie: I aged less than you did at the relative times we got there)

AHHH! One more...

YES.... If I hauled butt across the universe and came back...you would be much older and I would still be young. But my clock ticked the same as yours. As I was seemingly slowing to no movement from YOUR perspective, MY watch was still counting off regular seconds.

To a humming-bird we are as slow as snails. But a snail can barely detect the passage of time at all. Their time is in such slow motion that time passses before they can even effectively react.

[Ken G]

Asking how the "less part of reality" is interpreted into reality by the two observers. does each observer use the two sets of information of motion & time separately or is it motion, time combined to create a one summed time that is then interpreted by each observer?

I would say the latter, if it is clear we are talking about the conceiving of time for someone else, not the experiencing or measurement of time for ourselves (which has a reality in its own right, as it is directly measurable).

[RussT]

I'll assume you mean "imperceptibly close to the speed of light". The answer requires no "tactics", merely knowledge of relativity. The answer is that I will not be going 4 light years into your past, because light years are a distance, not a time. Furthermore, I will also not be going 4 years into your past, because you are simply mistaken that things separated from you "are in your past". There is a way, using Einstein's simultaneity convention, to completely consistently extend the concept of time to distant events such that they are in your present.

So the answer to all this is, you need to learn some relativity before you can say anything meaningful in terms of critiquing it. But after you do learn relativity, you will find that the underlying answer behind the question you should be asking is that time is fundamentally a local concept, so if you want to extend it globally to distant objects, you are doing something purely conceptual that will require you provide some instructions for how you want to do that-- "some assembly is required".

Geez Louise.....

The answer requires no "tactics", merely knowledge of relativity.

SO, you start right off with a "Tactic"!

It might even be funny if it weren't so sad!

The answer is that I will not be going 4 light years into your past, because light years are a distance, not a time.

what part of the word 'year' do you not understand as time???

It takes 4 'years' for light to travel from Alpha Centauri to earth, at the speed of light, 186,000 mps...hence the word Light "Year"why am I having to even explain this???

When we see HST photos of galaxies 5 billion lys away, we are seeing them as they were 5 billion years ago ie; where they were 5 billion years ago when their light left them to come to us...ago means past...

Furthermore, I will also not be going 4 years into your past, because you are simply mistaken that things separated from you "are in your past".

This is also funny...the wall across from my desk is IN my past...

Geez...your now is ONLY right where you are...anything seperated from your now by any distance, requires light to travel to you at "c" to see it, so you simply divide the distance by the speed of light to get how long AGO the light left. Again, why am I having to explain this?

There is a way, using Einstein's simultaneity convention, to completely consistently extend the concept of time to distant events such that they are in your present.

Yes, thus my statement...

If I explain the 'Illusion' that revolves around 'simultaneity' here, I will be banned, so...

And then your conclusion...

So the answer to all this is, you need to learn some relativity before you can say anything meaningful in terms of critiquing it. But after you do learn relativity, you will find that the underlying answer behind the question you should be asking is that time is fundamentally a local concept, so if you want to extend it globally to distant objects, you are doing something purely conceptual that will require you provide some instructions for how you want to do that-- "some assembly is required".

Is a Total Tactic...designed to impune ME and the simple question that I asked by having to 'mislead' and obfusicate what is really happening.

You see, I do 'really' understand this, because I know that IF...you just look at the 'going to somewhere' part, Without the turn around and then using..."Einstein's simultaneity convention", then the going out speed and time simply are not conceivable.

SO, I'll rephrase the question so that the...nothing of mass can reach the speed of light, will be eliminated.

Take off in your spaceship at 99% the speed of light from earth and go to Alpha Centauri, 4 light years away.

How is it possible to get ~4 years in my past in "Nano-seconds"???

[Ken G]

SO, you start right off with a "Tactic"!

Crying "tactic", in place of an actual argument, is a tactic itself.

what part of the word 'year' do you not understand as time???

I was pointing out that the better word in your statement would have been "year", not "light year", but your statement is still quite wrong either way so the distinction hardly matters.

When we see HST photos of galaxies 5 billion lys away, we are seeing them as they were 5 billion years ago ie; where they were 5 billion years ago when their light left them to come to us...ago means past...

That is actually sort of correct, depending on what one means by "5 billion light years away". We do in fact see light from distant places at a retarded time from when the light was emitted, using the Einstein simultaneity convention. Your error is in connecting that with the idea that because we are seeing the past, the distant object is somehow in our past. That is simply incorrect usage of time in relativity, because we correct for the light travel time before conceptualizing time for that distant object. I don't know what else to tell you-- google the "Einstein simultaneity convention" if you actually want to learn how time works in that theory.

This is also funny...the wall across from my desk is IN my past...

Same error again. The wall does not "have" a time, so it is not "in your past". You are seeing it as it was in your past, but there is still a concept of your present that applies to the wall (assuming it is still there). You are making the classic error of mistaking light time-of-flight effects for how time works in relativity, when in fact relativity is what appears after you have corrected for the time of flight effects. If you don't believe me, note that when you hear sounds from distant objects, you hear an event that occured in your past, but none of that has the least to do with relativity-- Galileo, for example, was well aware of the finite speed of sound when he formulated the relativity that was used pre-Einstein.

More to the point, your claim was that if I travel at very close to the speed of light to alpha Cen, that I somehow arrive in your past. This is flat wrong. It is true that if I do that, and send a signal back to you, you will not receive that signal until 8 years after I leave. That is all you can say, it says nothing about me being in your past (indeed everything I do on alpha Cen will occur in your future, relative to my departure time). Think this correct statement through very carefully, or you will never have any hope of understanding relativity, and will continue to critique it entirely on the basis of your own misconceptions. If you don't care, that's fine, others will just have to see through it.

Geez...your now is ONLY right where you are...anything seperated from your now by any distance, requires light to travel to you at "c" to see it, so you simply divide the distance by the speed of light to get how long AGO the light left. Again, why am I having to explain this?

You are only explaining your own misconceptions, which have been obvious to us all from the start. If you don't like being the only one who doesn't get it, I suggest you make the google I suggested, and think about what I'm telling you. If you still think you are right and I am wrong, then you can try again to make an argument, but please don't make statements about "now" that do not correctly reflect how relativity defines that word. As I said, you are right that "now" is only a transparent concept when treated "here", but nevertheless relativity finds ways to extend the concept elsewhere, and you are not doing relativity until you learn how that works. Then, and only then, can you meaningfully critique it.

You see, I do 'really' understand this, because I know that IF...you just look at the 'going to somewhere' part, Without the turn around and then using..."Einstein's simultaneity convention", then the going out speed and time simply are not conceivable.

No, you don't understand. Relativity is a theory, and part of that theory is Einstein's simultaneity convention. This immediately implies two things:
1) You have to use that convention or you are not doing relativity.
2) You are not allowed to say "I don't like that convention so I'm not using it, and furthermore, when I don't use it, relativity doesn't work". No kidding.

How is it possible to get ~4 years in my past in "Nano-seconds"???

I have answered this above, and again here. No one is going into your past that way. You cannot critique relativity until you know how to use it. If you dispute that, you must either establish that you are allowed to critique something you don't know how to use, or that you are in fact using relativity correctly.

[speedfreek]

Take off in your spaceship, "At the Speed Of Light", from Earth and travel to Alpha Centauri, ~4 light years from Earth.

How is it possible that you traveled 4 light years into my past virtually instantaneously???

If I were to travel to a star 4 light years away and back at a speed so close to c that it only took me 1 second each way, and you knew I was doing it, you might want to consider me to be at that star only a second after I departed. But then you have to think of the return journey in the same way, don't you? So I should be back home only 2 seconds after I departed, but that would obviously be false from your point of view, as it would take me over 8 years to return, so you shouldn't really be considering it that way, should you?

[steve000]

Yes, both match up time intervals such that the other has aged less, even though they are both aging at the same rate when referenced to their own sense of time.

OK..I've thinking about this Time dilation and trying to connect it to the physical world... would it be correct to look at it like this?

Each observer has to take into account the distance the other observers second travels through time (the faster the motion be-tween each observer, the longer the distance be-tween each second?). So the length of time between relative seconds is longer compared to each observers normal seconds?
Motion requires each second of normal time to travel further in relative time?

[Ken G]

Each observer has to take into account the distance the other observers second travels through time (the faster the motion be-tween each observer, the longer the distance be-tween each second?). So the length of time between relative seconds is longer compared to each observers normal seconds?
Motion requires each second of normal time to travel further in relative time?

Yes, I think the way this is often said is that we perceive everything as moving through spacetime at the same rate (one unit of proper time per unit of proper time), but if we perceive a motion through space, that contributes to the total motion through spacetime, leaving less for the motion through time alone.

[steve000]

Yes, I think the way this is often said is that we perceive everything as moving through spacetime at the same rate (one unit of proper time per unit of proper time), but if we perceive a motion through space, that contributes to the total motion through spacetime, leaving less for the motion through time alone.

To be honest I'm not getting (understanding) the separation of motion through space-time & motion through time... Is it basically saying that it all contributes to the length of relative time between the 1 unit of proper time and another unit of proper time?

[Ken G]

Think of it like this. Everyone has their own concept of the amount of time between two events, but the only person who actually experiences that time interval is someone who was at both events. That person can call the time interval the "proper time". Everyone else will conceptualize a shorter time interval (acceleration or gravity complicates this, but let's not go there yet). You can think of the reason that everyone else conceptualizes a shorter time is that to them, part of the elapsed time between the events actually shows up as a spatial displacement between them, whereas the person who was at both of them sees them as being at the same place (we never see ourselves as moving). In the case of the traveling twin, he can be at both events and still get a shorter time than someone else at those events (his twin), but that's because he accelerated when we was far away, so he can't see the events as being at the same place (it wouldn't make sense).

[EvilEye]

There was a great episode of Mork and Mindy (ironically) that perfectly explained all this.

Mork went into high-speed, and they showed it from both perspectives.

When seeing everything from Mork's point of view, everyone was going very slow, but aging at HIS time, while he just moved about normally.

When viewed from the perspective of those he was moving about, he was nearly invisible...incredibly fast... so from their point of view he aged only the 2 seconds they saw, while in fact he sauntered about screwing with them for 15 minutes.

(not accurate, but a way to explain it.)

edit: Therefore...he was IN FACT younger by 14 minutes 58 seconds than they were when he rejoined their speed.


edit again... He aged only 2 seconds in THEIR 15 minutes, while They experienced his 15 minutes in 2 seconds.

[hhEb09'1]

edit again... He aged only 2 seconds in THEIR 15 minutes, while They experienced his 15 minutes in 2 seconds.

DId they explain all that in the show?

Because, if they were going slow, wouldn't their body functions/processes also slow down? In other words, they experienced two seconds, so they aged two seconds. I think that is Ken G's axiom.

[EvilEye]

DId they explain all that in the show?

Because, if they were going slow, wouldn't their body functions/processes also slow down? In other words, they experienced two seconds, so they aged two seconds. I think that is Ken G's axiom.

Now I'm confusing myself. I need to go to bed earlier.

[EvilEye]

OK... they BOTH passed through the same static 15 minutes. But for him he did it in only 2 seconds according to their reletive timeframe. Therefore he aged slower. He experienced all 15 actual minutes in just 2 seconds. And they experienced the full 15 minutes from their own.

[hhEb09'1]

OK... they BOTH passed through the same static 15 minutes. But for him he did it in only 2 seconds according to their reletive timeframe. Therefore he aged slower.

But he spect fifteen of his own minutes "aging", surely that has some effect?

Why would the others age 15 minutes? They only experienced 2 normal seconds.



We could get in trouble, discussing Orkan physics

[EvilEye]

That's the paradox that you get when you put the observers in close proximity.

The faster person has aged less than those around him.

It just works that way.

[Ken G]

It's certainly how it works on Mork and Mindy.

[hhEb09'1]

That's the paradox that you get when you put the observers in close proximity.

The faster person has aged less than those around him.

It just works that way.

But the faster person also experiences less. So, a true paradox, thanks to Robin Williams, comic and genius.

[steve000]

Think of it like this. Everyone has their own concept of the amount of time between two events, but the only person who actually experiences that time interval is someone who was at both events. That person can call the time interval the "proper time". Everyone else will conceptualize a shorter time interval (acceleration or gravity complicates this, but let's not go there yet). You can think of the reason that everyone else conceptualizes a shorter time is that to them, part of the elapsed time between the events actually shows up as a spatial displacement between them, whereas the person who was at both of them sees them as being at the same place (we never see ourselves as moving). In the case of the traveling twin, he can be at both events and still get a shorter time than someone else at those events (his twin), but that's because he accelerated when we was far away, so he can't see the events as being at the same place (it wouldn't make sense).

The rate between 1 unit of proper time and the next unit of proper time is dependent on the velocity of the two events? The faster the velocity (in the relation to the two events) then the more time we spend in motion in space-time and less motion in time. reaching light speed, the rate of proper time is zero?...

http://www.phy.syr.edu/courses/modul...trail-v=8-A.rm
--
(Twin Paradox Question)
From the point of view of the twin on Earth, does the relative time of the twin at the point of U-turn on the journey nearly stop (or does stop? like the relative time is turning back on itself)?

http://upload.wikimedia.org/wikipedi...ki_diagram.png

[Ken G]

The faster the velocity (in the relation to the two events) then the more time we spend in motion in space-time and less motion in time. reaching light speed, the rate of proper time is zero?...

It is not us that are experiencing motion in space rather than time, it is the other observer, as far as we are concerned. We are in essence being egocentric and imposing our concept of time onto someone else, even though that other person has a clock and is perfectly capable of constructing their own concept of time based on that clock. If we forget about gravity and acceleration for the time being, so deal only with "inertial frames" of reference, then our own frame is always completely stationary, so is moving "entirely through time" at rate unity. But we can conceive of other observers in other frames who are in motion, so some of their movement, from our perspective, is through space, which means less of their movement is through our concept of time. That's why we interpret them as moving more slowly through time than we are, even though they see themselves as stationary, their own clock as working fine, and we who are moving partially through space.

(Twin Paradox Question)
From the point of view of the twin on Earth, does the relative time of the twin at the point of U-turn on the journey nearly stop (or does stop? like the relative time is turning back on itself)?

From the point of view of the twin on Earth, who does not accelerate, nothing special happens when the other twin turns around-- all that matters is the other twin is moving, so the stationary twin matches up longer segments of his own time with shorter segments of his twin's time. The U-turn does create weird effects for the traveling twin, because the traveling twin at first is also matching up longer segments of his own time with shorter segments of the stay-at-home twin's time, but during the U-turn, a vast amount of the stay-at-home twin's time gets matched up with a tiny amount of the traveling twin's time. That is what allows their matching-up processes to agree when they reunite, but not at every point along the way. The reason behind the weirdness at the U-turn is that the simultaneity convention changes suddenly for the twin that turns around. Nothing like that happens for the stay-at-home twin because he does not change speed (he's not on a rocket, after all).

[steve000]

It is not us that are experiencing motion in space rather than time, it is the other observer, as far as we are concerned. We are in essence being egocentric and imposing our concept of time onto someone else, even though that other person has a clock and is perfectly capable of constructing their own concept of time based on that clock. If we forget about gravity and acceleration for the time being, so deal only with "inertial frames" of reference, then our own frame is always completely stationary, so is moving "entirely through time" at rate unity. But we can conceive of other observers in other frames who are in motion, so some of their movement, from our perspective, is through space, which means less of their movement is through our concept of time. That's why we interpret them as moving more slowly through time than we are, even though they see themselves as stationary, their own clock as working fine, and we who are moving partially through space.

Yes I've got that (I think).....At the point in our normal time that we reach our normal second. From that point, the distance there second has to travel is what we perceive as there motion through space and less in our time.

It's the proper time that I'm grappling with.... I can understand one person at both events (theoretically speaking) and time running normally for him in proper time. Both observers at the events would have to take into account the distance the other observers second travels through time.
What relationship does proper time have to our time?

(quoted of a website)

the faster a system travels through space, the slower its internal processes go

Is that saying that the relationship of the two events, the proper time, that everything connected to those two events will run slower and slower (the proper time running slower and slower) with increased velocity.
And observers connected to the system of the two events their seconds would run slower and slower (if the velocity is increasing) from the point of view of a stationary clock (the clock being disconnected from the two events, but it can't be disconnected from the events..... Only theoretically)?

[Ken G]

What relationship does proper time have to our time?

Proper time is our time, it's the French meaning propre=own.

Is that saying that the relationship of the two events, the proper time, that everything connected to those two events will run slower and slower (the proper time running slower and slower) with increased velocity.

Proper time never runs slower, because it is the time experienced in the frame it is occuring. That's why I take issue with the wording from that website-- you often see it said that way, and it isn't exactly wrong, but it leads to misconceptions and worse of all it deflects from the importance of the concept of proper time. It basically takes the perspective of one observer, but to me relativity is above all the statement that we should express "reality" from the perspective of the person who was there, because the rest is just a conceptual mapping that may not preserve the sense of what is real.

[steve000]

Proper time is our time

So It's a simply a way of measuring the two events (or however many events there may be) as one?

(seems obvious now, a person at the two events would perceive a second as a normal second, as each observer at the events would do).

[EvilEye]

As I walk past you while you lounge in your chair, I age slower than you (however small that difference is), even though we are in each other's reference frame. My second and your second are the same reletive to US individually, but my second for you is faster. ...you have aged more than me by sitting still.

[Ken G]

(seems obvious now, a person at the two events would perceive a second as a normal second, as each observer at the events would do).

Yes, relativity retains an obvious aspect, that's important to recognize. Indeed, I would say that relativity is a means for identifying what remains obvious, even as other things become surprisingly subtle.

[Ken G]

As I walk past you while you lounge in your chair, I age slower than you (however small that difference is), even though we are in each other's reference frame. My second and your second are the same reletive to US individually, but my second for you is faster. ...you have aged more than me by sitting still.

That is true, but only because if you walk forever on a curved Earth, you have to keep returning to me. If you instead walked forever on a straight road leading off into space, you would always think that I have aged less than you have. One must not mistake relativity for saying that there is such a thing as absolute motion, such that what is in absolute motion will always age slower. It is the acceleration, that you need to keep returning to me, to circle my chair if you will, and not the walking itself, that causes you to match up less of your time with more of mine.

[EndeavorRX7]

Does someone who ages slower sleep more or less?

[astromark]

OK then... you can go rushing of at high velocities and age less than me, laying here in my hammock watching you. Then please do not keep coming back alongside me to com pair our respective ages and or time. Enjoy your ability to achieve such velocities and learn of the cosmos in doing so.
This constant disruption of you checking the time showing on my watch is getting tedious. Come back later.

Yes. I will sleep longer than you.

[Ken G]

Does someone who ages slower sleep more or less?

I've heard that animals age slowly when they hibernate, but I don't know anything about normal sleep, nor do I even know if the hibernation claim has been demonstrated. I don't know if we even really know what aging is, there may be many forms of it, that only correlate on average.

[Michael Noonan]

OK then... you can go rushing of at high velocities and age less than me, laying here in my hammock watching you. Then please do not keep coming back alongside me to com pair our respective ages and or time. Enjoy your ability to achieve such velocities and learn of the cosmos in doing so.
This constant disruption of you checking the time showing on my watch is getting tedious. Come back later.

Yes. I will sleep longer than you.

You are so lucky astromark,

I think I have lost about a year of sleep since I started writing here. All this business of checking watches reminds me of the story about a tailor with a measurement problem. You see his little foot was not the bigger size of a proper King's foot and so he was coming up short of the mark.

Enjoy your rest, cheers

[Jeff Root]

EvilEye,

Assuming that you correctly described Mork's actions and those of the
people he interacted with -- which I'm sure you did -- you described
the time relationship exactly backwards:

Mork went into high-speed, and they showed it from both perspectives.

When seeing everything from Mork's point of view, everyone was going
very slow, but aging at HIS time, while he just moved about normally.

When viewed from the perspective of those he was moving about, he
was nearly invisible...incredibly fast... so from their point of view he aged
only the 2 seconds they saw, while in fact he sauntered about screwing
with them for 15 minutes.

There are four basically different ways that could be done using Orkan
physics:

1) Mork could have taken Orkoids to increase his metabolism and
enhance his physiological capabilities. In this case, all the action
takes place in just two seconds, while Mork does 15 minutes' worth
of goofing off at super-speed.

2) Mork could have given the other people Letheum to slow down their
metabolism(s) and degrade their physiological capabilities. In this case,
anyone walking in on the scene would see things as Mork saw them.
Fifteen minutes actually pass, but to the people affected by Letheum,
it seemed like only two seconds. They look at their watches and find
that it is 14 minutes, 58 seconds later than they thought, the Sun has
seemingly jumped ahead in the sky, and Mindy's favorite movie, "Contact",
was already on TV and being recorded by her VCR which had the timer
set to record it.

3) Mork could have altered his own rate of passage through time
(or time's passage through him, whichever way you want to say it),
so that his own time was passing much more rapidly than that of anyone
else in the world. In this case Mort's clothes and pocket watch and
perhaps anything he was touching would match speed with him. His watch
would end up 14 minutes, 58 seconds fast relative to all the other
clocks in his time zone, he would be hungry for lunch 14 minutes,
58 seconds earlier (relative to Mindy's schedule) than he otherwise
would have been, he would need a shave 14 minutes, 58 seconds
earlier than otherwise (according to the sundial in the garden), and
his clothes would be in need of washing 14 minutes, 58 seconds sooner
than they would otherwise.

4) Mork could have altered the rate of passage through time of
everything in the room except himself and the things he was touching,
so that everything and everyone else in the room moved forward in time
at a slower rate than did the rest of the world. In this case, anyone
walking into the room would be slowed down as they came in. The
people in the room from the beginning would find that their watches
were 14 minutes, 58 seconds slow relative to clocks in the rest of the
house, and the rest of the time zone, and to Mork's watch. They would
find that the Sun had jumped ahead in the sky, and "Contact" was
already on TV in the next room, being recorded by the VCR.

edit: Therefore...he was IN FACT younger by 14 minutes 58 seconds
than they were when he rejoined their speed.

edit again... He aged only 2 seconds in THEIR 15 minutes, while They
experienced his 15 minutes in 2 seconds.

Both of those are backwards. It is the other way around, nomatter
which of the four methods Mork used.

In case (1) Mork aged 15 minutes physiologically while everyone else
in the world aged physiologically only a normal two seconds.

In case (2) everyone else in the room aged only 2 seconds physiologically
While Mork and people everywhere else aged the normal 15 minutes.

In case (3) Mork and his clothes and his watch actually aged 15 minutes
while everyone and everything else in the world aged only 2 seconds.

In case (4) Everything in the room except Mork and the things he was
touching aged only 2 seconds, while Mork, his clothes, his watch, the
TV in the next room, the cat upstairs, and everyone and everything
else in the world aged a normal 15 minutes.

-- Jeff, in Minneapolis