The Twin Paradox and Aging.

[dryson]

Is the Twin Paradox Correct?

In physics, the twin paradox is a thought experiment in special relativity, in which a twin who makes a journey into space in a high-speed rocket will return home to find he has aged less than his identical twin who stayed on Earth. This result appears puzzling on this basis: the laws of physics should exhibit symmetry. Each twin sees the other twin as traveling; so each should see the other aging more slowly. How can an absolute effect (one twin really does age less) result from a relative motion? Hence it is called a "paradox". In fact, there is no contradiction and the thought experiment can be explained within the standard framework of special relativity. The effect has been verified experimentally using precise measurements of clocks flown in airplanes.

http://en.wikipedia.org/wiki/Twin_paradox

This thought experiment is wrong. If one observer leaves the planet going as fast as light and the other observer remains in a fixed location for the duration of the flight of the ship traveling as fast as the speed of light, the observer in the starship will actually have aged more then the observer on Earth.

This can be proven by looking at what causes aging. We know that if we stay out in the sun for too long of a time then we will become sunburnt. What is a sunburn? A sunburn is the result of the human being saturated by too much UV radiation exposure. When too much UV radiation has been absorbed the body begins to go into overdrive trying to replace the dead and dieing cells. The process of replacing the lost cells put an increased stress on the body that produces the cells that have been destroyed. The stress that is placed upon the organs that produce the cells would then begin to place stress on the organs that support them, thus causing a deterioation of the organs that keep the body alive resulting in death.

As the starship accelerating at the speed of light away from the planet increases the distance from the Sun, the observer in the starship will actually have their age slowed down. This is because of the rate at which the cells reproduce given the amount of UV rays absorbed that would cause the cells to decay and need to be replaced. As the amount of UV becomes less and less the farther the starhsip moves away from the cell, the less stress there is that is placed upon the body as a whole. With less stress resulting in the need to reproduce cells to replace the dead and dieing cells caused by UV saturation, the body would then not produce as many cells which would slow the overall stress related affects that the body goes through during the process of replacing lost cells. This process would actually increase the person's life expectancy by maybe twenty to even fifty years. Now if the starship had a few families on it that conceived children after the starship had left the UV saturation zone of the Sun, the children would have developed an almost immortal age time frame over several generations. This would be due to the exchange of DNA information from the parents to the offspring where the offspring, because of the adaptive traits that the parents developed because of the lack of UV radiation being absorbed into the skin and causing cell loss, would not have the extra amount of stress placed upon their organs that would be associated with the observer on Earth, who is constantly being bombarded by UV radiation. Depending on how long the observer on the starship stayed outside of the range of the Sun's UV saturation range would determine who lived longer, the observer on the starship or the observer on the planet. The answer would be that both would age differently on a cellular level but on a level related to the amount of time that it takes the Earth to orbit the Sun would remain that same. The observer in the starship would not age on a cellular level but would age the same as the observer on Earth, making both observers the same Earth age. As the observer in the starship began their return to Earth at fast as light speed and encountered the outter range or zone of UV radiation the affects of cellular age would actually increase. This would be because of the UV stress placed upon the organs that replace the cells due to UV damage and decay not being able to handle the added affects of the UV radiation. The stress encountered would cause the body to work overtime replacing the lost cells which would cause the person to age more rapidly. If the observer on the starship made it back to Earth alive, due to the extreme amount of stress placed upon the bodies organs to replace the dead and dieing cells that would have adapted to the lesser amount of stress outside of the Sun's UV zone the Earth age of the two observers would be the same but the cellular age of the observer on the starship would actually have progressed to an age of maybe two hundred years old and in most instances would kill the observer on the starship because of the increased amount of stress placed upon the organs in the same way that the Sun burn did initially.

Any thoughts?

 

[ramparts]

In physics, the twin paradox is a thought experiment in special relativity, in which a twin who makes a journey into space in a high-speed rocket will return home to find he has aged less than his identical twin who stayed on Earth. This result appears puzzling on this basis: the laws of physics should exhibit symmetry. Each twin sees the other twin as traveling; so each should see the other aging more slowly. How can an absolute effect (one twin really does age less) result from a relative motion? Hence it is called a "paradox". In fact, there is no contradiction and the thought experiment can be explained within the standard framework of special relativity. The effect has been verified experimentally using precise measurements of clocks flown in airplanes.

http://en.wikipedia.org/wiki/Twin_paradox

Actually, the resolution does not come from special relativity. It comes from general relativity, which takes into account the effects of acceleration - the twin in the spaceship has to accelerate and then decelerate to make the trip, so there's no longer the symmetry you speak of. One observer is privileged over the other, and ages less.

This thought experiment is wrong. If one observer leaves the planet going as fast as light and the other observer remains in a fixed location for the duration of the flight of the ship traveling as fast as the speed of light, the observer in the starship will actually have aged more then the observer on Earth.

The observer in the spaceship does NOT move at the speed of light. That's impossible, sadly. The observer in the spaceship may (for best effect) move at some significant percentage of the speed of light, but never actually at the speed of light.

This can be proven by looking at what causes aging. We know that if we stay out in the sun for too long of a time then we will become sunburnt. What is a sunburn? A sunburn is the result of the human being saturated by too much UV radiation exposure. When too much UV radiation has been absorbed the body begins to go into overdrive trying to replace the dead and dieing cells. The process of replacing the lost cells put an increased stress on the body that produces the cells that have been destroyed. The stress that is placed upon the organs that produce the cells would then begin to place stress on the organs that support them, thus causing a deterioation of the organs that keep the body alive resulting in death.

As the starship accelerating at the speed of light away from the planet increases the distance from the Sun, the observer in the starship will actually have their age slowed down. This is because of the rate at which the cells reproduce given the amount of UV rays absorbed that would cause the cells to decay and need to be replaced. As the amount of UV becomes less and less the farther the starhsip moves away from the cell, the less stress there is that is placed upon the body as a whole. With less stress resulting in the need to reproduce cells to replace the dead and dieing cells caused by UV saturation, the body would then not produce as many cells which would slow the overall stress related affects that the body goes through during the process of replacing lost cells. This process would actually increase the person's life expectancy by maybe twenty to even fifty years. Now if the starship had a few families on it that conceived children after the starship had left the UV saturation zone of the Sun, the children would have developed an almost immortal age time frame over several generations. This would be due to the exchange of DNA information from the parents to the offspring where the offspring, because of the adaptive traits that the parents developed because of the lack of UV radiation being absorbed into the skin and causing cell loss, would not have the extra amount of stress placed upon their organs that would be associated with the observer on Earth, who is constantly being bombarded by UV radiation. Depending on how long the observer on the starship stayed outside of the range of the Sun's UV saturation range would determine who lived longer, the observer on the starship or the observer on the planet. The answer would be that both would age differently on a cellular level but on a level related to the amount of time that it takes the Earth to orbit the Sun would remain that same. The observer in the starship would not age on a cellular level but would age the same as the observer on Earth, making both observers the same Earth age. As the observer in the starship began their return to Earth at fast as light speed and encountered the outter range or zone of UV radiation the affects of cellular age would actually increase. This would be because of the UV stress placed upon the organs that replace the cells due to UV damage and decay not being able to handle the added affects of the UV radiation. The stress encountered would cause the body to work overtime replacing the lost cells which would cause the person to age more rapidly. If the observer on the starship made it back to Earth alive, due to the extreme amount of stress placed upon the bodies organs to replace the dead and dieing cells that would have adapted to the lesser amount of stress outside of the Sun's UV zone the Earth age of the two observers would be the same but the cellular age of the observer on the starship would actually have progressed to an age of maybe two hundred years old and in most instances would kill the observer on the starship because of the increased amount of stress placed upon the organs in the same way that the Sun burn did initially.

Any thoughts?

Yeah - when we talk about which twin ages more, we talk about how time passes differently for the two observers. You can think of it as having a clock on Earth and a clock in the spaceship, and seeing what time each clock measures the trip taking (the clock on the spaceship measures a shorter time). Nothing to do with UV radiation and the body's aging processes - we keep the thought experiment simple and ignore all that biological stuff It's to illustrate a point about time passage, not human biology.

Now, I'm no expert in biology (and somehow, I think, neither are you), but I would imagine that if you put the observer on a spaceship in a sealed box, so starlight didn't get in, you wouldn't have to worry about UV radiation - not to mention that for most of the trip you wouldn't be near any stars. Presumably the spaceship would include some sort of heat lamp to reproduce the Sun on Earth, or whatever else is necessary for these biological processes to continue as normal.

 

[origin]

Your whole argument is flawed because the cause of aging is not UV radiation. If that were true then you could live in a house that did not let in UV radiation and you would be immortal.

This is way beyond silly and has no place being in the physics forum!

 

[dryson]

Yeah - when we talk about which twin ages more, we talk about how time passes differently for the two observers. You can think of it as having a clock on Earth and a clock in the spaceship, and seeing what time each clock measures the trip taking (the clock on the spaceship measures a shorter time). Nothing to do with UV radiation and the body's aging processes - we keep the thought experiment simple and ignore all that biological stuff It's to illustrate a point about time passage, not human biology.

Now, I'm no expert in biology (and somehow, I think, neither are you), but I would imagine that if you put the observer on a spaceship in a sealed box, so starlight didn't get in, you wouldn't have to worry about UV radiation - not to mention that for most of the trip you wouldn't be near any stars. Presumably the spaceship would include some sort of heat lamp to reproduce the Sun on Earth, or whatever else is necessary for these biological processes to continue as normal.

You cannot dismiss the biological aspect of aging when aging relates to time, which for the most part I have never seen one discussion from Einstein about biological systems and how the enegetic systems relate to time it's always been based on energetic particles, which would make alot alot of what Einstein says only a half truth as biological systems are also part of the Universe as well as being part of an energetic system.

It doesn't take an expert to understand that when UV radiation destroy's the bodies cells the replacement of the cells put's an added amount of stress on the body. Here is an example, have you ever been outside on a real hot and humid day where you tried to do your daily activities but became worn out faster then you normally do? The reason why is because your body is being stressed to the point of severe fatigue because of the loss of water used in the process of replacing the lost cells due to the extreme amount of UV radiation that the body is absorbing. The additional stress then works it's way through the rest of the body in two ways the first being the constant replacement of the dead and dieing cells which places a level of stress on the body, the second is where the immune system is fighting the abnormal cellular growth associated with the cells that have mutated due to the extreme dosage of UV radiation. I learned about biology and energy while in school as well as watching many shows relating to the suns affects on a biological system as well as being trained in the USMC what happens when you are not hydrated, not hydrating yourself well enough will diminish the ability of the body to produce plasma which is the water in the blood that helps protect against UV radiation heating the cells up so that the cells do not mutate out of their normal cellular growth pattern. I also learned about the destruction of cells while weight lifting in highschool. During weight lifting the old muscles, which contain cells of different types, are being destroyed where new cells are being constantly reproduced to replace the old cells. During this process the heart especially is having an extreme amount of stress being placed on it which could cause the heart which is a muscle to tear and allow blood into the chest cavity which would cause death or a chamber in the heart to rupture which could lead to a heart attack and possible death.

I learned what I know from some very educated teachers who sought to teach science without the allegory of confusion involved in the teaching.

 

[ramparts]

Hi Dryson,

The twin paradox is a thought experiment. It's an idealization meant to explain principles of relativity, not to explain the precise biology of human aging.

But if you're really hung up over this, just imagine that both twins are placed in identical rooms with heat lamps, only one of those rooms is on a spaceship. Happy?

 

[darkmatter4brains]

Re: Is the Twin Paradox Correct?

Your whole aging argument lost me.

But the time dilation effect happens every second, every day. Muons,which are created in the upper atmosphere all the time from cosmic ray collisions, have a certain lifetime. Based on that lifetime, they should NEVER be able to reach the surface of the Earth. Yet, they do! Because their clocks are ticking slower with respect to our clocks on Earth.

The twin paradox is somewhat similar. You're right in saying that each twin will view the other as aging less on the journey out, but that is where the paradox lays. The trick to getting around it is to realize the twin on the voyage has to accelerate/deaccelerate to turn around and come home. Because his frame goes noninertial he suffers a huge time dilation at this this point, relative to the Earth observer - in fact a HUGE fraction of the all the time dilation happens during this point of the journey. In the end, his clock will have overall ticked less than Earth's clock and hence he will have aged less. Aging is a time-dependent physical phenomenon. If your clock ticks slower relative to another clock, you will also age slower.

 

[MeteorWayne]

Re: Is the Twin Paradox Correct?

Duplicate threads by dryson merged, duplicate post deleted.

 

[darkmatter4brains]

wayne, you probably didn't even need to merge my post. I didn't see this thread, but it looks like identical remarks were already made.

Actually, the resolution does not come from special relativity. It comes from general relativity, which takes into account the effects of acceleration - the twin in the spaceship has to accelerate and then decelerate to make the trip, so there's no longer the symmetry you speak of. One observer is privileged over the other, and ages less.

If I rememer correctly, this can also be done in Special Relativity in two different ways.

(1) Assume there is no acceleration/deacceleration when the voyaging twin reaches his/her destination, say Planet X. When he gets to Planet X, he/she will just instaneously swap inertial refence frames, from one heading out to Planet X to one heading back to Earth. When you examine the spacetime plots you can see he aged tremendously during this swap with respect to the earth observer. This is an approximation but shows similar results and still clarifies the paradox.

(2) The other way is convoluted. Let him accelerate and deaccelerate, but view it as a (very, very large) sequence of inertial frames. Each frame will have constant velocities, but with decreasing and then inreasing magnitudes as the voyaging twin turns around. Do your SR analysis frame by frame by frame by frame by frame by frame ....

I'm real rusty on my General Relativity but I think (2) is similar to that? Doesn't GR have the concept of a "local" inertial frame? In other words, any frame can be considered inertial if you look at it over short enough periods of time and space. An example being on a space ship in orbit. Given a long enough period of time two objects floating, but seemingly at rest, will actually get closer to one another over time since the gravitational force vector for each points radially towards the center of the Earth. But, it's such a small effect, it sure appears to be an inertial frame, even though it really is not.

 

[ramparts]

Well, I've never done the GR calculations myself, but if I recall it uses the equivalence principle to show that one side can be interpreted as experiencing gravitational time dilation.

 

[dryson]

But the time dilation effect happens every second, every day. Muons,which are created in the upper atmosphere all the time from cosmic ray collisions, have a certain lifetime. Based on that lifetime, they should NEVER be able to reach the surface of the Earth. Yet, they do! Because their clocks are ticking slower with respect to our clocks on Earth.

The twin paradox is somewhat similar. You're right in saying that each twin will view the other as aging less on the journey out, but that is where the paradox lays. The trick to getting around it is to realize the twin on the voyage has to accelerate/deaccelerate to turn around and come home. Because his frame goes noninertial he suffers a huge time dilation at this this point, relative to the Earth observer - in fact a HUGE fraction of the all the time dilation happens during this point of the journey. In the end, his clock will have overall ticked less than Earth's clock and hence he will have aged less. Aging is a time-dependent physical phenomenon. If your clock ticks slower relative to another clock, you will also age slower.

I think this is contrary to what I am trying to express, you continue to mention Earth based facts, which I on the other hand am mentioning facts that if a starship accelerates to the speed of light and escapes the suns UV radiation zone which causes cells to decay and be replaced that when you leave the Sun's UV radiation zone then eventually your body will not need to replace the cells as the damaging affect placed on the cells would not be present. The loss of UV radiation would therefore reduce the stress on the organs that produce the cells needed to replace the damaged and dead cells. Over time, which is a measureable distance of travel that an energetic body travels, based upon the energies own energetic particulars and how the interactions between the energetic body and medium that the particles are contained in create a distance between particle one and particle two, the observer will have evolved a new type of cellular system that would not produce the same amount of cells needed to replace the cells that have been damaged or have died. The reason being is because of the lesser amount of the Sun's UV radiation that is present that would be absorbed by the body thus causing damage to the cells in the first place. The zone that I speak of could be a few thousand miles outside of the solar system or the zone could be a few hundred thousand light years away from the solar system. This is a fact that we might not yet fully understand because of the lack of probes meant to study this type of UV radiation zone that would be able to communicate past Pluto. Once the observer on the starship decides to return to Earth, the process of increased aging would become more prevelant the closer to the Sun that the observer on the starship got to the Sun. This is because of the bodies inability to replace the cells that have been damaged due to the sudden increase of UV radiation from the Sun.

Aging is a time-dependent physical phenomenon. If your clock ticks slower relative to another clock, you will also age slower

This is not true. The process that you are talking about is chemical process in the brain. I have expierenced this many times where I have been at work and have not worried about what time it was which made the day seem to go by faster. Then there have been other days where I have constantly looked at the clock to measure how many parts were coming off of the press where the day seemed to drag on forever. But regardless of which theory I tested, the shift lasted eight hours from start to finish.

One unit of measure defined as a clock is used to measure the amount of time or the length of travel that the Earth completes in one day, meaning that the Earth, from starting point A to the same starting point A, will take 24 hours to complete. A calendar is also a clock that measures the amount of time or the lenght of travel that the Earth completes in one year, meaning that the Earth from starting point A to the same starting point, will take 365 days to complete.

Just because a clock slows down does not mean that the aging process will slow down because of the difference in time between the two clocks. Aging is based upon the bodies ability to replace cells damaged and detroyed by the Sun's UV radition. The farther away from the sun that you are the less you will age where you will have an increase in the aging process because of the amount of raditiation absorbed not because a clock ticks differently and may need wound up again because of the internal mechanism's involved with the clock's operation.

To be honest the age of digital time keeping has rendered the twin paradox of aging irrelevant because all cell phones and watches are synched to the atomic clock which is the most accurate time keeping device on the planet.

So if I have two clocks one that is ran on house power and the other one that is fully charged and independant of the house power and the power in the house goes off, does this mean that I will age slower because of the one clock not telling what time it is? No it doesn't I will age normally regardless of if the clock is on or off.

 

[darkmatter4brains]

Dryson says: "To be honest the age of digital time keeping has rendered the twin paradox of aging irrelevant because all cell phones and watches are synched to the atomic clock which is the most accurate time keeping device on the planet."

Try this out. Replace the human observers in the twin paradox with atomic clocks. Atomic clock A stays here on Earth. Atomic clock B goes on a voyage to the Andromeda and back. When they meet back up on Earth, atomic clock B will read a time that is earlier/less than atomic clock A. No humans, no cells, no worrying about a bad sunburn. Just pure, unadulterated Special Relativity at it's best.

If you still claim that is wrong, you may be up for a Nobel Prize, becaused you may have discovered a flaw in SR.

 

[darkmatter4brains]

Dryson,

Another way to think about this is like this.

Imagine a movie where for the entire 2 hours all you watch is a guy in a room sitting in his rocking chair sipping tea. Oh, and there is a clock on the wall ... let's say an atomic clock.

Now, get two copies of this movie and play each one on a seperate projector. So, you can watch the same movie on side by side screens. Here's the neat part - the one projector is going to play the movie at half speed.

You'll notice that the guy on the half speed projector is sipping his tea slower, rocking in his chair slower and the hands on the clock on the wall are also going slower. If you had an echocardiogram you would see his heart beating slower. You would also see his cells moving slower, his blood moving through his veins slower. etc, etc.

EVERYTHING is moving slower in that movie relative to the other one. Time is creeping at a slower rate - half the rate in this example. But, the guy in the movie doesn't even notice, because his perceptions are effected as well. His whole "reality" is literally proceeding along at a slower pace than the guy in other movie.

This is analagous to what Special Relativity claims. With time dilation ... all physical process slow, or dilate.

 

[MeteorWayne]

dryson, you seem to be using "clock" in the physicsl sense. It doesn't make any difference how the time is measured, whether mechanical, electyronic, atomic or whatever.

The point is that time passes slower, not that necessarily that a clock measures it slower. Clocks do, but that's not the point. An atomic clock would measure the same amount of time reduction as a mechanical one, or an egg timer.

 

[dryson]

Another way to think about this is like this.

Imagine a movie where for the entire 2 hours all you watch is a guy in a room sitting in his rocking chair sipping tea. Oh, and there is a clock on the wall ... let's say an atomic clock.

Now, get two copies of this movie and play each one on a seperate projector. So, you can watch the same movie on side by side screens. Here's the neat part - the one projector is going to play the movie at half speed.

You'll notice that the guy on the half speed projector is sipping his tea slower, rocking in his chair slower and the hands on the clock on the wall are also going slower. If you had an echocardiogram you would see his heart beating slower. You would also see his cells moving slower, his blood moving through his veins slower. etc, etc.

EVERYTHING is moving slower in that movie relative to the other one. Time is creeping at a slower rate - half the rate in this example. But, the guy in the movie doesn't even notice, because his perceptions are effected as well. His whole "reality" is literally proceeding along at a slower pace than the guy in other movie.

This is analagous to what Special Relativity claims. With time dilation ... all physical process slow, or dilate.

No not really, due to the fact that the frame rate at which the movie is being played on the projector is at a slower rate because of the technology used ,the rate of time for the man in the rocking chair would appear slower because of the number of frames that are seen per second whereas in a current day method of producing a movie the frames at which the actual movie is taken is taken at faster rate and is displayed at a faster rate.

Even though the men in the three different movies may appear to be moving at different times one being slower then the other two one being faster then the other two and the third one being faster then the slower one but slower then the faster one still has the same constant value, the intial man in the rocking chair still existed in the same time frame of when the pictures were taken regardless of how fast the equipment that is used to view the pictures actually made the pictures appear to slow down thus making the man appear to be moving slower in time.

 

[darkmatter4brains]

No not really, due to the fact that the frame rate at which the movie is being played on the projector is at a slower rate because of the technology used ,the rate of time for the man in the rocking chair would appear slower because of the number of frames that are seen per second ...

Dryson, r u serious! Or, are you just trying to pull people's legs on here

 

[MeteorWayne]

I assure you, he believes it. Gimme a "U"

 

[ramparts]

darkmatter, I think you missed the five-page thread a couple of months ago where dryson tried desperately to convince us that gravity is a form of magnetism :lol:

 

[Planet_Lubber]

You don't need GR (general relativity) to describe the motion of an accelerating object. A rocket can accelerate all over the place at relativistic speeds and you can still describe the motion in SR, as long as you stay away from place-times with significant curvature. You don't need curved space-time in order for something to accelerate.

With an accelerating object, like a spaceship, you can no longer use the LT (Lorentz transformation) the same way as before, because the reference frame carried along by the ship is not an inertial one. That doesn't mean that space-time has become curved, or that SR no longer applies. You can still use the LT for instantaneous co-moving inertial reference frames. There is still a gamma factor between an inertial frame and the accelerating frame, but gamma is not constant. The proper time (i.e., time experienced and measured, as it affects aging) on the ship is the integral of 1/gamma, with respect to inertial time.

There is a lot of literature on this subject, as a quick google search will show. However, most of the literature is restricted to motion with constant acceleration, or at least motion in one spatial dimension. One of my interests (I'll get around to it one of these days...) is to work out some 3 + 1 dimensional navigation and guidance laws, taking special relativistic effects into account. On this there is very little literature.

 

[origin]

I can't decide if dryson is more screwed up on physics or biology. His views are so completely out of whack it is really hard to decide.

If aging is only caused by UV from the sun, I suggest you wear a sombraro (or have a guy follow you around with an umbrella like Michael Jackson did) and you will live forever.

One of the most bizzare points of this is he keeps talking about his wonderful education!?! :shock:

 

[dryson]

dryson, you seem to be using "clock" in the physicsl sense. It doesn't make any difference how the time is measured, whether mechanical, electyronic, atomic or whatever.

The point is that time passes slower, not that necessarily that a clock measures it slower. Clocks do, but that's not the point. An atomic clock would measure the same amount of time reduction as a mechanical one, or an egg timer.

Time would pass for the same for the person twenty light years away as it would for the person on Earth. The only difference in the perception of time would be if another planet's daily revolution was used in stead of Earths.

Lets look at two planets Earth and Uranus. One Earth year is equal to 365.26 revolutions and Uranus' revolution is 84.01 years. This means that a person on Uranus would have a birthday denoting their day of birth every 84.01 years.
In the amount of time that a person one Earth would have had 84 birthdays a person on Uranus would only have had one birthday. If both of these people are placed side to side both of whom are the same age based on Earth years the Uranian would appear to be younger then the Earthling. This is not because of the amount of time but is because of the amount of UV radiation that each has obsorbed. The Uranian would ahve obsorbed far less UV radiation then the Earthling would have resulting in a much more youthfull looking person even though both were the same age, the Uranian would be 84 years of age based on Earths calendar but would only be a one year old on Uranus where the Earthling would be 84 years old on Earth but would be 1 year old on Uranus both being from the same date of birth but one being farther away from the sun and it's UV radiation and one being closer the the damaging affects of the suns UV radiation.

Time only appears to slow down for the Uranian when compared to the Earthling because of the aging process that relates to body obsorbing the suns UV radiation where the Uranian would be farther away from the sun then the Earthling would be.

 

[esokujo]

dryson, you seem to be using "clock" in the physicsl sense. It doesn't make any difference how the time is measured, whether mechanical, electyronic, atomic or whatever.

The point is that time passes slower, not that necessarily that a clock measures it slower. Clocks do, but that's not the point. An atomic clock would measure the same amount of time reduction as a mechanical one, or an egg timer.

Time would pass for the same for the person twenty light years away as it would for the person on Earth. The only difference in the perception of time would be if another planet's daily revolution was used in stead of Earths.

Lets look at two planets Earth and Uranus. One Earth year is equal to 365.26 revolutions and Uranus' revolution is 84.01 years. This means that a person on Uranus would have a birthday denoting their day of birth every 84.01 years.
In the amount of time that a person one Earth would have had 84 birthdays a person on Uranus would only have had one birthday. If both of these people are placed side to side both of whom are the same age based on Earth years the Uranian would appear to be younger then the Earthling. This is not because of the amount of time but is because of the amount of UV radiation that each has obsorbed. The Uranian would ahve obsorbed far less UV radiation then the Earthling would have resulting in a much more youthfull looking person even though both were the same age, the Uranian would be 84 years of age based on Earths calendar but would only be a one year old on Uranus where the Earthling would be 84 years old on Earth but would be 1 year old on Uranus both being from the same date of birth but one being farther away from the sun and it's UV radiation and one being closer the the damaging affects of the suns UV radiation.

Time only appears to slow down for the Uranian when compared to the Earthling because of the aging process that relates to body obsorbing the suns UV radiation where the Uranian would be farther away from the sun then the Earthling would be.

Let's suppose you place one twin on Earth, the other on Mars. While the one on Mars experiences a Martian year nearly twice that of Earth's, they would experience much more in terms of UV radiation (warning, I may be over-stepping my bounds with this assumption as I'm not a scientist and playing from memory) due to a lack of atmosphere/magnetic field. So in that case, the person on Mars would actually age more, according to your argument, given that they would have more UV radiation affecting them. But why make the argument with Earth and Uranus, when people here of the same age in years age at different rates physically?

The Twin Paradox has NOTHING to do with UV radiation and EVERYTHING to do with time. You seem unwilling to let go of that fact, even when presented with the option of placing both people (on Earth and in the ship) inside of a room that UV radiation cannot penetrate. How would you assess the paradox at this point, where UV radiation is not a determinant of aging?

 

[SpeedFreek]

Yes, it's all about the rate at which atoms "vibrate" - the atoms in atomic clocks and the atoms in our bodies.

 

[mabus]

Yes, it's all about the rate at which atoms "vibrate" - the atoms in atomic clocks and the atoms in our bodies.

Ok but the person would still age would he not? Or are you saying that the person in the thought experiment is merely an analogy for an atom like the cat in Shroedinger's box?

 

[SpeedFreek]

Ok but the person would still age would he not? Or are you saying that the person in the thought experiment is merely an analogy for an atom like the cat in Shroedinger's box?

Sorry, I was a little ambiguous there. The thought experiment is about time and uses the difference in the respective ages of the twins to illustrate that time is relative. The ageing process is considered to be a given.

The difference in the paths that the twins take through space-time, between when the paths separate and when they converge again, accounts for the difference in their ages. The longer path through space takes a shorter path through time.

 

[mabus]

Ok but the person would still age would he not? Or are you saying that the person in the thought experiment is merely an analogy for an atom like the cat in Shroedinger's box?

Sorry, I was a little ambiguous there. The thought experiment is about time and uses the difference in the respective ages of the twins to illustrate that time is relative. The ageing process is considered to be a given.

The difference in the paths that the twins take through space-time, between when the paths separate and when they converge again, accounts for the difference in their ages. The longer path through space takes a shorter path through time.

Right... but my understanding is that the thought experiment is meant to convey what happens in a macroscopic sense to macroscopic objects when they undergo relativistic events. That the twins represent actual twins of human size, and not atoms, am I mistaken? Just want to get that clear because if I am mistaken about this then that has serious implications.