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Einstein's paradox

 
 
mark noble
 
  1  
Reply Sun 23 May, 2010 07:05 pm
@prothero,
prothero;167821 wrote:
From wikipedia on the twin paradox, you can find the same on more academic sites.

from pbs nova special on einstein and relativity, use the internet and stick to physics sites or reliable academic sites.


Hi Prothero,

Excuse my interuption, but, If Al is travelling at 99.99% the speed of light and the system he is travelling to and from is 25 light years away, won't he take 25 years to get there and 25 years to return - Therefore aging by 50 years?

Thank you, and best wishes.

Mark...
prothero
 
  1  
Reply Sun 23 May, 2010 08:18 pm
@mark noble,
mark noble;167851 wrote:
Hi Prothero,

Excuse my interuption, but, If Al is travelling at 99.99% the speed of light and the system he is travelling to and from is 25 light years away, won't he take 25 years to get there and 25 years to return - Therefore aging by 50 years?

Thank you, and best wishes.

Mark...
Well you see it is that problem with the way we typically think about time again. It is best to think of time as the rate at which certain processes occur, radioactive decay, aging, crystal oscillation, orbital emissions. Once you view time as process, the rate at which processes occur varies with acceleration and gravitational fields, so the "25years" is only from the frame of reference of the non traveling twin. For the traveling twin all these processes slowed (thus time slowed) and so the traveling twin does not age at the same rate as the stay at home twin. It is counterintuitive to our experience of the world and the notion we have of the constant unit of time but time is variable not fixed, and so is space and and other physical measurements. That is what is revolutionary about special and particulary general relativity notions of spacetime. Yes for us here on earth 50 years worth of process will have passed but for the accelerating twin much less.
Atomic clocks in orbit at high speeds keep time differently than those here on earth, GPS satellites have to account for relativistic effects, particles with certain 1/2 lives find there lives extended at high speeds in particle accelerators. Time (which funadmentally is the rate at which certain processes occur, not some independent fixed entity) is variable hence all the confusion in the various time threads in the forum. This is not my opinion. It is physics.
Huxley
 
  1  
Reply Sun 23 May, 2010 08:24 pm
@Flying Dutchman,
Flying_Dutchman;167806 wrote:
I'm fairly certain that is precisely what relativity does not imply, because that information is wholly dependent on reference frame. There is no other data about which object is "actually" moving. If you take away all outside reference frames (thus isolating the actual motion of the two objects without any other aesthetic confusions), it can't be known which object is moving away from the other. Each particle or twin (at least in an otherwise objectless universe) would see the other as younger. And each would be correct from his perspective.


According to SR, yes. But SR only applies to mathematical transformations of physical quantities between reference frames that are inertial, and therefore can be in motion, but that are not accelerating. When an inertial reference frame accelerates, and thereby is no longer an inertial reference frame, SR no longer applies. But the paradox arises, at least in my experience, only from SR. General Relativity... I'm less familiar with. At that point, I can't meaningfully comment. I just know that GR is where the solution to the paradox lies.
0 Replies
 
Flying Dutchman
 
  1  
Reply Mon 24 May, 2010 11:44 am
@prothero,
prothero;167872 wrote:
Well you see it is that problem with the way we typically think about time again. It is best to think of time as the rate at which certain processes occur, radioactive decay, aging, crystal oscillation, orbital emissions. Once you view time as process, the rate at which processes occur varies with acceleration and gravitational fields, so the "25years" is only from the frame of reference of the non traveling twin. For the traveling twin all these processes slowed (thus time slowed) and so the traveling twin does not age at the same rate as the stay at home twin. It is counterintuitive to our experience of the world and the notion we have of the constant unit of time but time is variable not fixed, and so is space and and other physical measurements. That is what is revolutionary about special and particulary general relativity notions of spacetime. Yes for us here on earth 50 years worth of process will have passed but for the accelerating twin much less.
Atomic clocks in orbit at high speeds keep time differently than those here on earth, GPS satellites have to account for relativistic effects, particles with certain 1/2 lives find there lives extended at high speeds in particle accelerators. Time (which funadmentally is the rate at which certain processes occur, not some independent fixed entity) is variable hence all the confusion in the various time threads in the forum. This is not my opinion. It is physics.



So I agree with you and what I've read about the change in intertial frame solving the paradox. I still don't know why you want to say that one twin (or piece of uranium) is absolutely moving as opposed to the other. Motion is defined via reference frames. You can't say that one object is definitively the one in motion without regards to just another reference frame.

Just to be clear, absolute motion is a really big debate. So each of our views is valid in that respect.
0 Replies
 
laughoutlood
 
  1  
Reply Tue 15 Jun, 2010 01:26 am
http://off-hour-rockers.com/Y23_Exploding_Clock_Dali_Salvador.jpg

Dilatory isn't it.

http://en.wikipedia.org/wiki/Time_dilation
0 Replies
 
Sentience
 
  1  
Reply Sun 4 Jul, 2010 09:56 pm
The idea is that time is relative and the faster you go, the slower you age (the actual idea that it is the speed of light doesn't matter, I think, but it would require such a speed to make it feasible). This is known as Time Dilation. It has been proven, as they put an atomic clock on the ground and one in a jet plane and one measured (I think it was) .01*10^-6 less time had passed then the other.
0 Replies
 
Doubt doubt
 
  1  
Reply Wed 8 Sep, 2010 11:53 am
@kennethamy,
Something like that yes. It appears to me that Einstein is always talking about perception. one twin would perceive the other as younger. all that matters is how many times the earth goes around the sun. one twin could look like a baby but if the earth goes around the sun ten times then they are both ten years older. a year, age, and older are all human concept. you would have to create a new term for that thought experiment to mean anything.

the classic example is Einsteins example about a person bouncing a ball on a train. the bouncer perceives the ball as going down and up. the person on the ground perceives the ball as bouncing in a V. the fact is the ball does what it does without the perceptions of the observers making any difference at all. if anything it is related to optics but in no way does the observers observation effect the physical world. physics does not concern perception. it concerns the behavior of physical objects. how we perceive physical objects is optics, not physics.
0 Replies
 
Doubt doubt
 
  1  
Reply Wed 8 Sep, 2010 12:04 pm
@Yogi DMT,
moving matter makes it vibrate faster. we call this an increase in temperature. it would be just as likely that temperature slows down the clock as does the speed. temperature expands metal which would make more friction. I just mean we can never control the experiment enough to prove anything. basically we are taking a mind our body creates to help us thrive in the food, survival sense and attempting to solve physical mystery's with it. chances are we will never solve the mystery's of the universe. on thing i am certain of is that mathematics is not the answer. people seem to forget that the greatest minds in history all agree that mathematics and geometry only coincidentally represent the physical world on occasion.
Doubt doubt
 
  2  
Reply Wed 8 Sep, 2010 12:09 pm
@kennethamy,
kennethamy wrote:

Yogi DMT;147717 wrote:
What if the box contains two inertial systems (which i'm not quite sure what this means). All i'm saying is if you look at the huge picture, why would time be any different in any particular place.


Bu the box could not contain two inertial systems. Einstein is discussing physics, and physics need not be commonsense. You really would have to look this matter up. Why not try Googling "the twin paradox"?


"If you can't explain something simply, you don't know enough about it."
"It should be possible to explain the laws of physics to a barmaid"
"You do not really understand something unless you can explain it to your grandmother. "

three Einstein quotes.
0 Replies
 
Doubt doubt
 
  1  
Reply Wed 8 Sep, 2010 12:11 pm
@kennethamy,
kennethamy wrote:

Yogi DMT;147723 wrote:
Okay, i probably don't know enough about this then. I just had discussion in English that's really all.


Well, discussions in ignorance usually don't lead anywhere much.


I bet the farm you are a mathematician with a bad case of sunk cost effect.
0 Replies
 
Doubt doubt
 
  1  
Reply Wed 8 Sep, 2010 12:28 pm
@jeeprs,
jeeprs wrote:

No, that is not it. There are some Time Life explanations of how relativity works that might help you. It would be easier with a diagram but here goes. Two spaceships, right? You're on one and George is on the other. Relative to you, George goes by at quite a few million miles an hour. Woosh.

Now in each spaceship, there is a clock. The clock works by firing a beam of light at the mirror on the floor once a second. This is how it keeps time. The clock on George's spaceship does this too. But, relative to you, the mirror in George's spaceship has actually travelled quite a few thousand miles between the time the beam left the roof, and hit the mirror on the floor, and then another few thousand miles on the return trip.

From where George is standing, the light has just made a standard round trip of a few meters. From where you are standing, the light has travelled a few thousand miles. Light always travels at the same speed.

Therefore the time taken for the light beam on George's spaceship has taken longer relative to you than it does, relative to George.

So the clock is actually running slower on George's spaceship.

hope that helps.


So how do these space ships effect the rate at which the earth goes around the sun? How does the accuracy of their clocks pertain to the earth spinning. if im on earth and the earth spins once on its axis it a day has passed. you could do a lap around the universe but to everyone on earth you were gone a day. you could come back a purple baby but you aged a day as far as the definition of a day is concerned. unless there is a new definition of a day i have not heard about.

IS the claim that you could do more than a years worth of living in a year traveling at the speed of light? how does looking younger pertain to being younger? how does a clock which does not work properly at the speed of light have anything to do with the time it takes the earth to spin on its axis and rotate around the sun? how does the perception of the passage of time of people on a spaceship correlate to the rotation of the earth and the people on it?

0 Replies
 
HexHammer
 
  1  
Reply Wed 8 Sep, 2010 12:30 pm
@Doubt doubt,
Doubt doubt wrote:

moving matter makes it vibrate faster. we call this an increase in temperature. it would be just as likely that temperature slows down the clock as does the speed. temperature expands metal which would make more friction.
You have a bad graps on the definition on things.

- people in flight, trains ..etc does not have their temperature increased once they are accellerated enough.

- it's "heat" not temperature and pressure that expands metal.
0 Replies
 
Doubt doubt
 
  1  
Reply Wed 8 Sep, 2010 12:40 pm
@jeeprs,
jeeprs wrote:

wayne;147809 wrote:
Does a mechanical clock actually run slower, or does this only affect the light clock?


TIME actually slows down on George's ship. If he goes far enough, fast enough, 30 years for him will be 150 years on earth. But it is all theoretical. We don't have the technology, or the energy, to actually realise this effect, but the principle is clear. Time slows down the faster you go, relative to a stationary observer.


Relative to the stationary observer?? how is the observers perception relevant to physics? I dont see any claim about any physical objects. Like Kant says Time is the perception of erosion by a subject. no subject no time. If you fly to space and do who knows what all that matters is the earth keeps doing what it does regardless of the perceptions of one guy on a ship. for all we know travel at the speed of light converts white blood cells into LSD and then where are we.
0 Replies
 
Doubt doubt
 
  1  
Reply Wed 8 Sep, 2010 12:48 pm
@jeeprs,
jeeprs wrote:

Not exactly. In the time it takes the light to travel two meters on your ship, it has travelled thousands of meters on George's ship. Visualize George's ship going past you - you're both in space, you can see it coming from 10,000 kilometers away. Lightbeam leaves origin point on George's ship, by the time it hits the mirror on the floor, the ship has moved several hundred thousand meters. And even though light moves pretty quickly, that difference is measurable.

So again, if George's ship is moving at millions of kilometers an hour, relative to you:

  • From George's viewpoint, he sees the beam go straight down and straight back up
  • From your viewpoint, if you could see the lightbeam in George's ship, you would see it travel obliquely for several hundred thousand meters in each direction, to 'keep up' with the motion of the ship
  • So the distance the light beam has to travel, according to your frame of reference, is not two meters, but two hundred thousand meters (say)

And even though light is fast, the speed is finite, so it takes longer, from your frame of reference, for the beam on George's ship to make its return journey.

So time is actually moving slower on George's ship. it is not an illusion, an appearance, or the way the clocks work. The faster you go, the slower time is for you, relative to a stationary observer.


once again. all you are saying is two people can perceive the passage of time differently. that is not a claim about the physical aspect of time or light it is a claim fit for Optics or biology. of course time can be perceived differently for people. anyone that has ever been in a car crash could tell you that. I have seen time almost stop and i was only moving 40 MPH. i have seen time fly when i was having fun. point is it makes no difference how i perceive the passage of time. the earth keeps turning and the sun keeps burning. when you have dreamless sleep you do not time travel. things go normal for everyone else. its normal for you as well but you perceive it differently. This is all perception and not physics.
parados
 
  1  
Reply Wed 8 Sep, 2010 01:41 pm
@Doubt doubt,
Quote:
once again. all you are saying is two people can perceive the passage of time differently. that is not a claim about the physical aspect of time or light it is a claim fit for Optics or biology

It's not a case of perception. It's a case of reality.
Time slows for someone moving faster.

The speed that the earth travels around the sun is relative to your observation point. It isn't a constant. For an observer traveling 1/2 the speed of light, the earth would go around the sun 2 times per year as measured by an atomic clock traveling with them.
0 Replies
 
mark noble
 
  1  
Reply Wed 8 Sep, 2010 04:41 pm
@Doubt doubt,
Well Said!

How time is perceived has nothing to do with the physical factors present in this physical universe. It doesn't matter how far or how fast you travel, your age will age in accordance to the revolutions of the planet that depicts the label of time that you are obliged to.

And E=mc2 does it? Of course it does - EVERYTHING equals mc2. What else could it possibly equal?

And black holes do NOT alter the flow of time - Because time is an imaginary human concept that is no more than a measurement. Measurements are non-physical applications (labels).

Time is a just a label.

No two things are identical - Nothing doesn't exist - And I'm off to bed.

Goodnight!
Mark...
0 Replies
 
 

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