• Jackslap

#### Jackslap

I'm kind of a noob who's posted a question or two here before to settle arguments and such. Please don't kill me if this has been covered before.

I was reading some stuff about space travel trying to get some creative ideas for a sci/fi book idea I had. Nothing serious and really nothing to do with the twin paradox, but I stumbled across that and had a thought.

I was reading about it on wikipedia and the example used there is one of twin "A" making a trip of 4.45 light years at a speed of .866c. Of course for simplicity they assume that the velocity is reached instantly. Upon twin "A"s return, twin "B" would have aged 10.28 Earth years, while twin A would have only aged 5.14. Aside from the complicated (for me) math that they used to generate these results I understand the idea. BUT...

What would the twins look like physically? If my thoughts are correct, shouldn't they still be the same height/weight etc? What I'm thinking is the human body ages based on it's own biological clock right? It doesn't trigger growth hormones or the aging process based on it's location on Earth right? So the 10 Earth years/5 Earth years thing doesn't really matter here.

I started thinking of it like this: If it were possible for twins to be born at the same instant on opposite sides of the galaxy, and then relocated instantly to a neutral location, wouldn't they be the same? The Earth years number is just an arbitrary number that WE use because it's how we understand time. The human body does it's own thing.

How far off am I?

If you reach 86.6% of the speed of light you will be traveling at 259620268 m/s if you were to travel 4.45 light years away it would take exactly 5.14 years to reach the destination and another 5.14 years to get back. So I think Earth a and b are 4.45 light years apart.

Um...I'm confused.

Did I not ask the question clear enough? What does restating the provided information in the OP accomplish?

They say growth is accelerated in space because of the zero gravity. And that it changes the way a body structure is formed. Look up Dr. Holton this could explain your confusion.

What would the twins look like physically?
This is not about the aging process, and not abhout different conditions the twins have been living in.
For one twin, 10 years passed, for the other 5. With all consequences.
If it were possible for twins to be born at the same instant on opposite sides of the galaxy, and then relocated instantly to a neutral location, wouldn't they be the same?
if this were possible, relativity would be wrong. A phrase like "at the same instant on opposite sides of the galaxy" has no well-defined meaning in relativity, and you can't check "instantly" different clocks at different positions.
The Earth years number is just an arbitrary number that WE use because it's how we understand time. The human body does it's own thing.
You're reading too much into these "earth years". That's just "years", used to measure time. One and the same time for clocks, nucleons, minds, and bodies, btw.

What would the twins look like physically? If my thoughts are correct, shouldn't they still be the same height/weight etc? What I'm thinking is the human body ages based on it's own biological clock right? It doesn't trigger growth hormones or the aging process based on it's location on Earth right? So the 10 Earth years/5 Earth years thing doesn't really matter here.
I don't really understand what you're asking. Their weights will of course depend on what they've been eating for all those years. People's heights also tend to change over time. (Kids get taller, old people get shorter).

I started thinking of it like this: If it were possible for twins to be born at the same instant on opposite sides of the galaxy, and then relocated instantly to a neutral location, wouldn't they be the same?
I don't think the question makes sense as it stands, because there's no theory that allows instant relocation. If they're going to meet at the neutral location, their ages when they meet will depend on how they moved to get there.

I don't really understand what you're asking. Their weights will of course depend on what they've been eating for all those years. People's heights also tend to change over time. (Kids get taller, old people get shorter).

I don't think the question makes sense as it stands, because there's no theory that allows instant relocation. If they're going to meet at the neutral location, their ages when they meet will depend on how they moved to get there.

I'm amused at the discussion so far. A lot of information that is new for me. But I'm confused about the above quote. Fredrik disqualifies the question due to the fact that there is no theory that supports instant travel, but does not object when I mentioned twins being born at the same time, on opposite sides of the galaxy. Of course NEITHER of those things can happen, but for the sake of argument assuming there WAS a way to instantly relocate (teleport...whatever) wouldn't the twins be the same age biologically?

For the sake of further clarification let me adjust the hypothetical situation and state that in this case the twins are both female. They are genetically identical and perfect in every way. The hormones and genes that will trigger puberty are going to fire up at the exact same moment (measured in Earth years). They will begin their menstrual cycle on the same day, same second...except as we know, twin A will begin her journey at .866c while twin B stays on earth. Shouldn't they both be then menstruating upon twin A's return to earth, even though she's only 5 years old? ( I know I know, twin B is 10 and most girls don't start that early either, but some do so let's assume that these twins do to).

So essentially their bodies are the same physically even though the number that annotates their "time on earth" so to speak differs?

How can approaching the speed of light affect the bodies aging process is what I don't get I guess?

If I were to approach and then go BEYOND the speed of light (I know I know, but come along with me) would that be some sort of fountain of youth? As long as the body keeps traveling faster and faster toward infinity, it just stops growing, aging etc? Where can I learn more about this?

What would the twins look like physically? If my thoughts are correct, shouldn't they still be the same height/weight etc? What I'm thinking is the human body ages based on it's own biological clock right? It doesn't trigger growth hormones or the aging process based on it's location on Earth right? So the 10 Earth years/5 Earth years thing doesn't really matter here.

Time runs slower. That means 5-earth year boy will still only be five. He will look like 10-earth year boy did 5 years ago. And 5 years ago, 5-earth year boy will look like a toddler(2.5years).

Carl Sagan explains it in another way

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I'm amused at the discussion so far. A lot of information that is new for me. But I'm confused about the above quote. Fredrik disqualifies the question due to the fact that there is no theory that supports instant travel, but does not object when I mentioned twins being born at the same time, on opposite sides of the galaxy. Of course NEITHER of those things can happen, but for the sake of argument assuming there WAS a way to instantly relocate (teleport...whatever) wouldn't the twins be the same age biologically?

For the sake of further clarification let me adjust the hypothetical situation and state that in this case the twins are both female. They are genetically identical and perfect in every way. The hormones and genes that will trigger puberty are going to fire up at the exact same moment (measured in Earth years). They will begin their menstrual cycle on the same day, same second...except as we know, twin A will begin her journey at .866c while twin B stays on earth. Shouldn't they both be then menstruating upon twin A's return to earth, even though she's only 5 years old? ( I know I know, twin B is 10 and most girls don't start that early either, but some do so let's assume that these twins do to).

So essentially their bodies are the same physically even though the number that annotates their "time on earth" so to speak differs?

How can approaching the speed of light affect the bodies aging process is what I don't get I guess?

If I were to approach and then go BEYOND the speed of light (I know I know, but come along with me) would that be some sort of fountain of youth? As long as the body keeps traveling faster and faster toward infinity, it just stops growing, aging etc? Where can I learn more about this?

When your two twins are traveling relative to each other, they measure time and space differently. As strange as this might seem, this is the way the universe is put together.

This means that if Our Earth twin were watching his brother in a telescope, he would see the his brother is aging more slowly (this is after he compensates for the time it takes the light reach him from his brother.) his heart beats slower, his hair grows slower, his movements are slower, etc. When he returns he will be 5.14 years older biologically while the stay at home twin will have aged 10.28 yrs biologically.

The traveling twin notices nothing of this. As far as he is concerned, he ages normally. What he does notice is that the distance between the Earth and the point where he turns around is only 2.225 ly. (this same distance is 4.45 ly by the Earth twin's measure). Since it only take 5.14 yrs to out and back to a point 2.225 ly at 0.886c, this is how long the trip is by his clock (biological clock included).

Thus according to the Earth twin his brother aged less because time ran slower for him, while the traveling twin says he aged less because the trip was shorter in distance.

Thank you Janus! Exactly the explanation I needed. And Tcheq for the video link, I had forgotten about that portion of "Cosmos".

It is still a hard thing for me to grasp, but I have fleeting moments where I feel I'm starting to understand it. Maybe that's the sign that I'll soon have it in full. Since I'm not studying physics in any way, I don't have the knowledge necessary to formulate the most educated of thoughts and so I appreciate everyones help.

I didn't take much physics in school (radiation physics for x-ray tech school) I don't spend much time with it, but I'm becoming fascinated with all the fun little thoughts a person can have.

When I asked earlier about the "fountain of youth" thing, it wasn't until later that I realized that I was really beginning to ask about time travel. If there was a magic speed at which aging simply froze, then there must be a theoretical speed at which aging would be reversed then right? Essentially time travel.

I'm amused at the discussion so far. A lot of information that is new for me. But I'm confused about the above quote. Fredrik disqualifies the question due to the fact that there is no theory that supports instant travel, but does not object when I mentioned twins being born at the same time, on opposite sides of the galaxy. Of course NEITHER of those things can happen, but for the sake of argument assuming there WAS a way to instantly relocate (teleport...whatever) wouldn't the twins be the same age biologically?
Identical twins born on planets at opposite sides of the galaxy, at events that have the same time coordinate in the inertial coordinate system in which Earth is not moving, is not in violation of the laws of physics. It's difficult to accomplish, but possible in principle. But to ask what happens if you instantly relocate someone, that's like asking if you would still be hungry if you ate yourself for dinner. It's logically impossible, at least in the theories that I was supposed to use to answer the rest of your question. You're asking what relativity would be saying if it had been a different theory which is logically inconsistent.

For the sake of further clarification let me adjust the hypothetical situation and state that in this case the twins are both female. They are genetically identical and perfect in every way. The hormones and genes that will trigger puberty are going to fire up at the exact same moment (measured in Earth years).
Are you still talking about twins that start out far apart?

If you mean "at events that are assigned the same time coordinate by the inertial coordinate system in which Earth is not moving", this isn't going to happen if one of the twins is on a journey towards the other. But maybe that's not what you meant. What's going to happen is that the clocks they carry with them will show approximately the same time at the two events where their "hormones and genes fire up".

How can approaching the speed of light affect the bodies aging process is what I don't get I guess?
Human bodies can be considered "clocks". They're not as accurate as, let's say the clock on your cell phone, but they're still clocks, and a clock measures the proper time of the curve in spacetime that represents its motion.

If I were to approach and then go BEYOND the speed of light (I know I know, but come along with me) would that be some sort of fountain of youth?
Again, a question doesn't make sense if it assumes something that contradicts the theory that's supposed to answer the question.

You can go arbitrarily go arbitrarily close to the speed of light relative to some other object, like the Earth, but no matter how fast you go, it won't increase the amount of experiences you can have before you die.

What would the twins look like physically? If my thoughts are correct, shouldn't they still be the same height/weight etc? What I'm thinking is the human body ages based on it's own biological clock right? It doesn't trigger growth hormones or the aging process based on it's location on Earth right? So the 10 Earth years/5 Earth years thing doesn't really matter here.
Here is an explanation I gave some time ago on this topic.

So, from this comment it seems that you understand time dilation for light beam clocks. Remember that special relativity is founded on two postulates.

1) that all the laws of physics are the same in all inertial reference frames
2) that the speed of light is the same in all inertial reference frames

So the part that you understand, the time dilation of a light clock, is primarily based on the second postulate. But to understand how we make the jump from light clocks to time in general you need to consider the first postulate:

Imagine that we have a light clock, an atomic clock, a piezoelectric quartz clock, a windup spring clock, and a rat with a really steady heartbeat. All are clocks working on different physical principles. Because the laws of physics are the same in all inertial reference frames (first postulate) if they all beat at the same rate in one frame they must all beat at the same rate in any other frame. So, in an inertial frame where the clocks are moving at relativistic velocity, because the light clock slows down the other clocks must also slow down or the laws of physics would be different. Therefore, because any physics expression with a "t" in it must slow down, we say time slows down.
All biological processes can be considered to be (inaccurate) clocks. So if all clocks slow down then so do all biological processes, otherwise you could determine absolute speed by comparing the rate of biological processes to other clocks. This would violate the first postulate of relativity.

if this were possible, relativity would be wrong. A phrase like "at the same instant on opposite sides of the galaxy" has no well-defined meaning in relativity, and you can't check "instantly" different clocks at different positions.
It seems like no one on this thread has actually used the phrase "relativity of simultaneity", might help to do so since then Jackslap could look it up (and find pages like this one and this one) if he wanted to learn a little more about it. Basically the relativity of simultaneity says that events that happen at the same time (simultaneously) in one frame happen at different times in other frames, and according to the first postulate of SR, no frame's perspective is physically privileged over any other frame's. So this is why the phrase "same instant" has no objective frame-independent meaning in relativity, and similarly why instantaneous travel doesn't make sense in SR (even if the event of an object dematerializing at one location happened simultaneously in some frame with the event of it rematerializing at another location, in other frames the rematerialization would happen some time after the dematerialization, and in still other frames the rematerialization would happen before the dematerialization).

It seems like no one on this thread has actually used the phrase "relativity of simultaneity", might help to do so since then Jackslap could look it up (and find pages like this one and this one) if he wanted to learn a little more about it. Basically the relativity of simultaneity says that events that happen at the same time (simultaneously) in one frame happen at different times in other frames, and according to the first postulate of SR, no frame's perspective is physically privileged over any other frame's. So this is why the phrase "same instant" has no objective frame-independent meaning in relativity, and similarly why instantaneous travel doesn't make sense in SR (even if the event of an object dematerializing at one location happened simultaneously in some frame with the event of it rematerializing at another location, in other frames the rematerialization would happen some time after the dematerialization, and in still other frames the rematerialization would happen before the dematerialization).

It's not relevant to the understanding of the implications of time dilation.

I see no need to overword a discussion when a simple answer will do. I see it all too often, very recently, for example a 16 year old asked a simple question and people quoted GR equations in their replies. When I was 16 I barely understood what differential notation was, let alone double differential equations across a tensor in spherical coordinates.

The implications of GR isn't a complicated thing to understand. The maths that make it so might be, but that is unimportant unless you are a theoretical physicist, cosmologist or otherwise a complete psychotic. One job of a good scientist is to make the astoundingly overwhelming seem easy (because it is).

Bringing big words or concepts such as simultaneity into a simple discussion is like a GR dogmatist elbowing his way into a discussion on low-velocity physics, repeatedly poking a stick into the ribs of the group who can't remember in which case to use sin and cos, asking them where their gamma is.

Smokes, now you guys are blowing my mind. It is obvious that my comprehension of such complicated topics is infantile compared to some of you folks. I am still a bit confused about certain terminologies you guys use, since I have not had any formal education in physics. For instance, you all seem to speak of "frames" frequently. I'm supposing frames to mean an area or a range, perhaps a perspective. But maybe I'm not on target with that.

I obviously have much learning to do if I wish to carry on similar conversations with everyone. I feel a little more stupid now thank you very much.

I can take everyones word for it that my instincts were wrong on this one, that indeed the body's biological clock will slow down as accelleration of the body increases. I hear you, but still don't quite understand the why.

I can liken it my job in x-ray. Limited x-ray techs are button pushers, with little or no knowledge of radiation and how it's controlling factors can be used to manipulate radiographs. But fully licensed techs actually have a degree and understand the "why" radiation does what it does. I need to get to the "why" of all of this. I'm sure understanding comes with plenty of study and time.

TcheQ: In #7, Jackslap was talking about two girls, one of which was on Earth, and the other was traveling towards Earth in a spaceship at a relativistic speed, and he talked about how they would be having their first period "at the exact same moment (measured in Earth years)". This clearly indicates that he thinks of simultaneity as something absolute.

If you understand why that's a mistake, you also know that he has no chance of understanding what was wrong with that assumption until he has learned about simultaneity. So why the attitude? If you want to give him those "simple answers", then just do it. Save the agression for a time when its appropriate.

For instance, you all seem to speak of "frames" frequently. I'm supposing frames to mean an area or a range, perhaps a perspective.
Frame is short for "reference frame", and when that term is used in the context of special relativity, it always means "inertial reference frame". So what you need to know is just what an inertial reference frame is. I prefer a mathematical definition myself, but I think that would be of little use to you right now, so I suggest that you think of an inertial frame as an imaginary grid of meter sticks and synchronized clocks, all moving with the same velocity, and extending to infinity in all directions. You can use this grid to assign coordinates to events. I'm saying "imaginary" because we're going to have to consider at least two such grids moving at different velocities, so they'd have to be able to pass through each other.

The idea is that an inertial observer (someone or something that isn't accelerating) can use a grid that's co-moving with him to assign coordinates to events, and those assignments are what we're referring to when we talk about e.g. the length of an object "in his frame".

...the body's biological clock will slow down as accelleration of the body increases. I hear you, but still don't quite understand the why.
That part isn't really easy to explain, so you're going to have to study some SR if you really want to understand it. The easiest way to learn the basics of SR is to learn about spacetime diagrams.

Edit: After reading dacruick's response to this quote, I noticed that the quote gets it wrong. Time dilation isn't caused by acceleration. It only depends on the relative velocity of the clocks. (But be careful, a misinterpretation of that statement is what leads to the twin "paradox").

I'll add one more thing: Motion is represented mathematically by curves in spacetime. A point particle is an object whose motion can be represented by only one curve. Ideal clocks are treated as point particles. One of the axioms of SR is that a clock measures a certain mathematical property of the curve in spacetime that represents its motion. The fact that two different observers will disagree about how much time has elapsed between two events can be traced back to that. The properties of the clocks aren't different. It's just that they measure coordinate independent properties of different curves.

I'm sure understanding comes with plenty of study and time.
It does. SR isn't so hard to understand compared to many other things in physics. The math is very easy compared to GR or QM. Most of it can even be understood by drawing a bunch of straight lines on a piece of paper.

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I can take everyones word for it that my instincts were wrong on this one, that indeed the body's biological clock will slow down as accelleration of the body increases. I hear you, but still don't quite understand the why.
No ones biological clock slows down in their frame of reference. Time is normal for both the twin on Earth and the twin in the spaceship. Its just the concept that time is "elongated" at higher speeds. I mean this is all sketchy terminology and can be easily misinterpreted. You should look up anything that these fellows say as it will all be useful in helping you understand. But no ones clock slows down or speeds up, the clock stays the same. its just the value of time depends on your speed. I suggest you look up time dilation. There is an experiment that i remember really began to interest me in the concept of relativity. there are two mirrors traveling together with a ray of light bounces from one side to another.

It's not relevant to the understanding of the implications of time dilation.
The question was not solely about the implications of time dilation. As Fredrik said, this part of Jackslap's question seemed to require a response discussing how simultaneity isn't absolute in relativity:
Jackslap said:
I started thinking of it like this: If it were possible for twins to be born at the same instant on opposite sides of the galaxy, and then relocated instantly to a neutral location, wouldn't they be the same? The Earth years number is just an arbitrary number that WE use because it's how we understand time. The human body does it's own thing.

maybe to make it slightly more clear. in 1 second on earth, twin A's biological clock will carry out the same actions as twin B's biological clock will in a second. The only thing different is that if on Earth 2 seconds pass, 1 second will pass at .866c.

I think this is where your understanding breaks down. biological clock is dependent on time and time is dependent on speed. so at higher speeds, the biological is not affected by speed. say we want to define the biological processes of the brain(hormones etc) in a "reaction per second" unit. as you can see, no matter what speed there will be, there will still be the same reactions per seconds carried out by the brain. The only thing different between twin A and twin B is the amount of seconds that has passed, not the rate of biological processes.

You're right, this topic is mind blowing, keep asking questions. more questions, more answers, more understanding.

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Relativity eschews the concept of an absolute reference inertial frame. To conclude that one twin ages at a different rate than the other would require one to assign an absolute reference frame to one twin; in the case of the 'paradox', twin A. This actually violates Special Relativity. Both twins age at the same rate.
Ron

Relativity eschews the concept of an absolute reference inertial frame. To conclude that one twin ages at a different rate than the other would require one to assign an absolute reference frame to one twin; in the case of the 'paradox', twin A. This actually violates Special Relativity. Both twins age at the same rate.
Ron

which is what i said more or less in layman's terms.

The question was not solely about the implications of time dilation. As Fredrik said, this part of Jackslap's question seemed to require a response discussing how simultaneity isn't absolute in relativity:

I guess that's the problem with using (extremely poor) examples that can't ever be tested or observed. After all the twin paradox is just a spoon feeding to the gelatinous-cube masses to simulate what happens to particles and to make physics sound cooler than it really is (but it's already sub -273C°!)

So why the attitude? If you want to give him those "simple answers", then just do it. Save the agression for a time when its appropriate.

What is the point of one person giving simple answers to the degree of t/gamma, and the rest quoting enough journal articles and mathematical fluff to fill the Mir space station? The problem in #7 was still time dilation, and instead of saying "actually that's an extremely poor example who's details severely detracts from the original question, let's use a better one" you did the complete opposite. The fact that one entity is traveling at a speed required for the observance of time dilation is unimportant.

Perhaps I just find it unbelievable that after the number of posts I see, people are still unable to communicate it in a simple manner. It's basics. If people really want to learn more about it, lectures on youtube, books or shockhorror even university courses are readily available.

I sure did not mean to stir up an argument, but I have to admit that I did sort of confuse the matter in #7. My thought pattern lead me from one thing to another, and I discussed both thoughts in that one, unintentionally changing the subject a bit. One wrong thought led to another wrong thought.

I believe my error stemmed from taking the twin paradox idea and changing it so that BOTH twins would now be moving, instead of one staying still and the other accelerating. Plus introducing the impossible idea of instant relocation of matter.

But now that I've said that, haven't I just brought up some other principle? Something about how it doesn't matter which twin is moving, that one twin could always consider his frame is the moving frame and the other standing still? I know that I just changed the subject again, but this is all leading me toward better understanding. Essentially the twin that is hurtling through space AWAY from Earth at .866c could merely consider that Earth is really just moving AWAY from him at .866c and he's still right?

Thanks to Tcheq, dacruick, and Fredrik for the recent chip ins. Your past few posts have really given me some things to study and have helped me graps this a bit better.

I wish I had the time and money to study this full time in school. How much did you all spend for your degrees? Worth every penny I'm sure. You all know stuff that average fools like me can't begin to fathom.

... I believe my error stemmed from taking the twin paradox idea and changing it so that BOTH twins would now be moving, instead of one staying still and the other accelerating. ...

This is the crux of the misunderstanding. Neither twin is 'staying still'. Unfortunately everything is moving relative to something else. That is why no clock actually runs slower than any other clock. The appearance of time dilation is not an actual slowing of anything, only a phenomenom applied to an observer's observation of a different inertial frame. Remember, there is no absolute reference frame.
Ron

Damn you Ron for taking all of my "almost there" understanding and throwing a bomb in it! I understand everything you just said. I can accept it as fact. But then how is it that time dilation is not a slowing of anything? I had just established that one twin is actually younger than the other one upon returning to Earth (or Earth returning to him depending on perspective). But if nothing really slows, why are their ages different?

Am I taking you guys in cirlces here or what? Sorry to bother if so.

I do however understand that there is no absolute reference frame though. What that means to me is that if I, a neutral observer in this traveling twin thought, were to see the whole thing unfold from some point other than twin A or B, I would see things different than either of them did. Meaning that there really is no neutral way to observe this event. Everyone will have a difference of opinion of what really happened based on their own location.

Yeah I know. I actually took a long time to phrase the first post I made in this thread. I could already hear the screams of 'blasphemy' and 'heretic'! But the simple fact is that any observer is as preferred as any other; no more, no less. The actual 'paradox' is only in the phrasing of the riddle. By saying 'B' appears to 'A' to be running slower does not translate to the oft-quoted conclusion that 'B' is in reality running slower than 'A'. Just keep repeating: there is no absolute reference inertial frame, there is no absolute reference inertial frame, there is no absolute reference inertial frame . . .
Ron

I understand the clocks and time dilation sections, but when I get to the Lorentz Gamma Factor and the Paradox image I get lost again. The fact that the red perspective stays horizontal I get, but why does the blue need to be placed on a diagonal with a skewing of his "cone" area? Is this like the Einstein example of the ball being dropped from a train? That it travels on a diagonal to a "stationary" observer at the train station?

Keep in mind that what I've said flies directly in the face of about a century of some very smart people saying some very wrong things. I really don't have much hope of changing minds here with my humble postings, but I could not just sit here and let the fallacious ideas continue unchallenged. Even that really really smart guy on Discover channel gets it wrong. Neither clock slows down. End.
Ron

Wow! O.K. Ron I did not understand that you were actually challenging the facts that the other posters were bringing up, I thought I was misunderstanding you.

You are saying that in your opinion neither twins age would be different then? Because that was my first instinct, but I thought everyone here had solved for me why I was wrong. So now we really have come full circle.

Ron, why then is there still a debate about this? After a hundred years like you said, why isn't there an agreement yet? Surely someone has nailed this down definitively right?

Not really challenging facts, just keeping the conclusions in check. I understand and believe in Special Relativity. In doing so, and being intellectually consistent and honest, I can only conclude that a clock moving relative to another clock appears to tick more slowly but in fact does not actually tick more slowly. Again, to conclude that it does would be to assign preference to the faster clock. This is a violation of SR.
Thanks,
Ron

So I have just only begun to understand the difference between GR and SR according to lectures on youtube (thanks TcheQ for the suggestion, why didn't I think of that?). Ron, you are saying then that there is still a group of people who don't believe in SR? I only ask that because you singled yourself out by saying "I believe in SR" as though some don't.

Why the debate, shouldn't special relativity just be accepted as fact? Someone is saying Einstein was wrong? What have I missed?

BTW, my wife says I'm turning into an internet physics nerd. I said "You should see what THESE guys are saying, you think I'm nerdy"...

The thing is she loves her some nerds. She has a secret crush on Conan O'brien. Yuck

There may be some who do not understand or believe in SR. I made that statement as a pre-emptive defense against someone who might claim that I don't. The mathematics of SR are basically inarguable. One thing that could possibly negate SR is if someone were to show that an observer measures something other than the same well-established c for the (local) speed of light. That woukl be earth-shattering. Meanwhile the Theory, if kept within its limitations, works quite well. (I have actually downloaded a copy of On the Electrodynamics of Moving Bodies in English, read it, and understand it.)
I've avoided posting any opinion yet in this thread. Since you asked, I think that some people get so buried in the fantastical specific notions implied by Relativity that they lose sight of reality. In constructing a particular Gedanken like the 'twins paradox', one must be careful to maintain the aforementioned intellectual integrity. The key is to always remember the two postulates stated by Einstein in his paper; this should help keep things grounded.
Another thing to keep in mind is that Einstein (and others) have described various physical actions but still have not explained the actions. Fodder for another thread . . .
Ron

This is the crux of the misunderstanding. Neither twin is 'staying still'. Unfortunately everything is moving relative to something else. That is why no clock actually runs slower than any other clock. The appearance of time dilation is not an actual slowing of anything, only a phenomenom applied to an observer's observation of a different inertial frame. Remember, there is no absolute reference frame.
There's nothing controversial in here.
Yeah I know. I actually took a long time to phrase the first post I made in this thread. I could already hear the screams of 'blasphemy' and 'heretic'! But the simple fact is that any observer is as preferred as any other; no more, no less. The actual 'paradox' is only in the phrasing of the riddle. By saying 'B' appears to 'A' to be running slower does not translate to the oft-quoted conclusion that 'B' is in reality running slower than 'A'. Just keep repeating: there is no absolute reference inertial frame, there is no absolute reference inertial frame, there is no absolute reference inertial frame . . .
...or here. It just sounds like you want people to call you a blasphemer.

Keep in mind that what I've said flies directly in the face of about a century of some very smart people saying some very wrong things. I really don't have much hope of changing minds here with my humble postings, but I could not just sit here and let the fallacious ideas continue unchallenged. Even that really really smart guy on Discover channel gets it wrong. Neither clock slows down. End.
I have no problem believing that Discovery channel gets it wrong, but it still sounds like you just believe people are saying things they aren't actually saying. I agree that the function of a clock is in no way disturbed when it's given a different velocity. It's still measuring the proper time of the curve that represents its motion, but that's now a different curve than before.

Not really challenging facts, just keeping the conclusions in check. I understand and believe in Special Relativity. In doing so, and being intellectually consistent and honest, I can only conclude that a clock moving relative to another clock appears to tick more slowly but in fact does not actually tick more slowly. Again, to conclude that it does would be to assign preference to the faster clock. This is a violation of SR.
But it does "actually" tick more slowly in the other guys reference frame. (It would however be wrong to end the sentence after "slowly"). If A and B don't have the same velocity, then A's clock is slow in B's frame, and B's clock is slow in A's frame.

Far be it for me to take on Mr. Michio Kaku, the really really smart guy I was referring to. But I have watched the shows he narrated about Time and remember distinctly the leap he made from stating one clock appears to another to be ticking more slowly, to the statement (after a commercial break) that one clock is really ticking more slowly than the one that is implicitly now preferred. The conclusion was unmistakable due to the implications of long distance space travel being accomplished by flying really fast (compared to what? is the question), same as the 'twins paradox'. The popular notion is that one clock, and one twin, experiences time flow more slowly, is pervasive and just plain wrong.
Hope we agree.
Ron