# can time actually slow down?

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Without going back and re-reading the thread, I think you can safely ignore anything posted by "GeneralDadmission". He posted a lot of nonsense from what I remember.

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Thanks Janus,

You've given me a lot to think about

Firstly, thanks for the insights.

When I say "at the same time" I am describing Party A and Party B, not the universal "at the same time", I assume that the further the distance between two or more objects the less accurate the "same time" is.

As long as you are at rest with respect to two events, neither the distance between the two, nor your distance from them has no effect on whether or not you judge them as being simultaneous or not. It's a difference in relative motion that causes one observer to say they were simultaneous and the other that they are not.

Secondly I would be considered quite mad to assume I am correct and the world of scientific leaders are incorrect, but I have a bug in my brain that I can't squash, and no matter how many different ways things are described or explained to me, I can't seem to evict this niggling creature from my mind. I guess the only real way to satisfy my mind would be for someone to time travel back to before I wrote this post and tell me to stop writing it.

Time Travel, Time dilation and causal relativity seem to me as barmy as a bucket of horses in a tadpole farm, I can't believe what the math says nor can I believe anything has been tested or proven either for or against the theory with satisfactory results. So for me to let go of my preconceived ideas, and adopt a new thought framework to base opinions on, I will need to watch someone bend space so much they can travel into the past to pat themselves on the back as they do so.

Special Relativity does not predict the ability to travel back in time, that is just a popular misconception. Neither, as I stated earlier, does it allow for the reversal of causality(for the effect to precede the cause). While it does say that two observer can disagree on the order of two events, this is not the case if the event are causally linked ( one event causes the other)

For example. A light flash is emitted from a point between two objects that is just a little closer to object 1 than object 2 (Event A). For anyone at rest with respect to the objects, the light will hits object 1(Event B) before it hits object 2(Event C) Thus the order of events is A-B-C. However for someone traveling at sufficient speed from object 1 to object 2, the light will hit object 2 before it hits object 1. Thus the order is A-C-B. Since event A is the cause of events B and C both observers agree it happened first. But since the light hitting object 1 has no effect on it hitting object 2, and vice-versa, these events are not causally linked to each other, and different observers can judge them as happening in different orders.

Time dilation, which is a prediction of Relativity, has been successively demonstrated in real life experiments. It is verified everyday in particle accelerators around the world, and, as pointed out earlier, has to be taken into account in designing the GPS system.

Now don't get me wrong, I'm not Copernicus. all I'm saying is, the science seems to say one thing is possible, but no one, ever has had a reported successful case. Meanwhile anyone (Including me) who attempts to suggest we may be barking up the wrong tree on this one is told to abandon their beliefs and join the herd on the greener side of the fence. I REALLY want to do that, but I am stuck on this Time Travel thing, which relativity doesn't forbid.

I am reminded of a limerick I heard once,

There once was a lady named Bright,

who could travel much faster than Light.

She left one day in a Relative way,

and came back the Previous Night.

I'm familiar with the limerick, and while cute, it is based on the same popular misconception as earlier. SR actually forbids Bright from even reaching the speed of light, let alone exceeding it. Saying the Relativity predicts that you go back in time by exceeding the speed of light, is like saying that you can prove that 1=2 as long as you are allowed to divide by 0. You can't use a theory to predict what happens if you go beyond the constraints of the theory.

We can throw all the science in the world at that poem, but I would still have to call SullBhit on that. (apologies for the filter evasion) and that's why I can't get my head around this thing. Not because I just don't want to, but because its as ridiculous as a bucket of horses in a tadpole farm.

For a long time, people thought the world was flat, and when the idea of a spherical world evolved, a good deal of them thought it was bollocks. If the world was round, they reasoned, it would have a top and a bottom, and if this is the case, what keeps the Oceans, people, etc from falling off the bottom?

Now, as much as we may laugh at this idea today, by the knowledge of the time, they had a point! You see, they had been taught,and everything around them told them that "down" was a universal, innate property of the universe. Their understanding of "Down" was as a single direction built into the reality of the universe. The idea that "down" could mean different directions to different people was, to use your own words, "as ridiculous as a bucket of horses in a tadpole farm".

That was the prevailing understanding of the nature of "down" at the time. Now for us today, it seems natural that "down" is the direction gravity pulls, and gravity pulls towards the center of the Earth, but at that time, that concept was a HUGE paradigm shift from what considered as the natural state of things, and such shifts in mental direction are not easily made.

Relativity requires the same type of paradigm shift and change of mental gears.

I hope, while making my feelings clear, and my sense of logic apparent, I have not offended anyone. If I have, I apologize wholeheartedly.

It's not a matter of taking offense, it's a matter of whether or not I'm wasting my time. Relativity is teachable, as whether or not it is learnable depends on the student.

My problem is not that the math..or science can prove that it's possible and can at least potentially become reality at some point, my issue is that we (the human race) allowed ourselves to go down this particular rabbit hole in the first place.

A large problem is that you are attributing predictions(such as time travel) to Relativity that it doesn't actually make. Many popular notions about the theory are not in fact part of the theory at all.

Those predictions that it does make have been verified again and again.(Unless you are claiming that all the published results of these tests are lies. And if so, to what purpose?)

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Special Relativity does not predict the ability to travel back in time, that is just a popular misconception. Neither, as I stated earlier, does it allow for the reversal of causality(for the effect to precede the cause). While it does say that two observer can disagree on the order of two events, this is not the case if the event are causally linked ( one event causes the other)

For example. A light flash is emitted from a point between two objects that is just a little closer to object 1 than object 2 (Event A). For anyone at rest with respect to the objects, the light will hits object 1(Event B) before it hits object 2(Event C) Thus the order of events is A-B-C. However for someone traveling at sufficient speed from object 1 to object 2, the light will hit object 2 before it hits object 1. Thus the order is A-C-B. Since event A is the cause of events B and C both observers agree it happened first. But since the light hitting object 1 has no effect on it hitting object 2, and vice-versa, these events are not causally linked to each other, and different observers can judge them as happening in different orders.

Time dilation, which is a prediction of Relativity, has been successively demonstrated in real life experiments. It is verified everyday in particle accelerators around the world, and, as pointed out earlier, has to be taken into account in designing the GPS system.I'm familiar with the limerick, and while cute, it is based on the same popular misconception as earlier. SR actually forbids Bright from even reaching the speed of light, let alone exceeding it. Saying the Relativity predicts that you go back in time by exceeding the speed of light, is like saying that you can prove that 1=2 as long as you are allowed to divide by 0. You can't use a theory to predict what happens if you go beyond the constraints of the theory.For a long time, people thought the world was flat, and when the idea of a spherical world evolved, a good deal of them thought it was bollocks. If the world was round, they reasoned, it would have a top and a bottom, and if this is the case, what keeps the Oceans, people, etc from falling off the bottom?

Now, as much as we may laugh at this idea today, by the knowledge of the time, they had a point! You see, they had been taught,and everything around them told them that "down" was a universal, innate property of the universe. Their understanding of "Down" was as a single direction built into the reality of the universe. The idea that "down" could mean different directions to different people was, to use your own words, "as ridiculous as a bucket of horses in a tadpole farm".

That was the prevailing understanding of the nature of "down" at the time. Now for us today, it seems natural that "down" is the direction gravity pulls, and gravity pulls towards the center of the Earth, but at that time, that concept was a HUGE paradigm shift from what considered as the natural state of things, and such shifts in mental direction are not easily made.

Relativity requires the same type of paradigm shift and change of mental gears.

It's not a matter of taking offense, it's a matter of whether or not I'm wasting my time. Relativity is teachable, as whether or not it is learnable depends on the student.

A large problem is that you are attributing predictions(such as time travel) to Relativity that it doesn't actually make. Many popular notions about the theory are not in fact part of the theory at all.

Those predictions that it does make have been verified again and again.(Unless you are claiming that all the published results of these tests are lies. And if so, to what purpose?)

Does time dilation also include the reverse phenomenon, something like time "speeding up"?

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My problem is not that the math..or science can prove that it's possible and can at least potentially become reality at some point, my issue is that we (the human race) allowed ourselves to go down this particular rabbit hole in the first place.

It's only a rabbithole to you, not others, because you don't understand it. SR is not a problem; learn what it actually describes..

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Time Travel, Time dilation and causal relativity seem to me as barmy as a bucket of horses in a tadpole farm, I can't believe what the math says nor can I believe anything has been tested or proven either for or against the theory with satisfactory results.

Why? Is your mind immune to evidence?

So for me to let go of my preconceived ideas, and adopt a new thought framework to base opinions on, I will need to watch someone bend space so much they can travel into the past to pat themselves on the back as they do so.

I realize you're joking, but we have a word for this and it's called being 'closed-minded.' You're setting an unreasonable standard of proof to avoid having to change your mind.

Now don't get me wrong, I'm not Copernicus. all I'm saying is, the science seems to say one thing is possible, but no one, ever has had a reported successful case.

Successful case of what? Time dilation? You've been given examples of experiments that successfully detect time dilation.

Meanwhile anyone (Including me) who attempts to suggest we may be barking up the wrong tree on this one is told to abandon their beliefs and join the herd on the greener side of the fence. I REALLY want to do that, but I am stuck on this Time Travel thing, which relativity doesn't forbid.

Beliefs should be based on evidence. If they aren't, they're delusions. You've been presented with evidence.

I hope, while making my feelings clear, and my sense of logic apparent, I have not offended anyone. If I have, I apologize wholeheartedly.

Science should not be considerate of feelings; yours, mine, or anyone else's.

My problem is not that the math..or science can prove that it's possible and can at least potentially become reality at some point, my issue is that we (the human race) allowed ourselves to go down this particular rabbit hole in the first place.

To what rabbit hole are you referring? The hole of following the evidence and trying to understand nature? I'm not sure why that's a bad hole to go down.

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Time Travel, Time dilation and causal relativity seem to me as barmy as a bucket of horses in a tadpole farm, I can't believe what the math says nor can I believe anything has been tested or proven either for or against the theory with satisfactory results. So for me to let go of my preconceived ideas, and adopt a new thought framework to base opinions on, I will need to watch someone bend space so much they can travel into the past to pat themselves on the back as they do so.

This is a straw man. Not relativity.

Now don't get me wrong, I'm not Copernicus. all I'm saying is, the science seems to say one thing is possible, but no one, ever has had a reported successful case.

If at first you have an epic fail, try, try again.

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Does time dilation also include the reverse phenomenon, something like time "speeding up"?

Relative to whom?

Since time is relative, this is a simple yes. When measured across two observers, it will have sped up for one and slowed for the other... relatively speaking.

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Relative to whom?

Since time is relative, this is a simple yes. When measured across two observers, it will have sped up for one and slowed for the other... relatively speaking.

When two observers are in relative motion, each considers the other to have slower time. That's what puts the (apparent) "paradox" in the "twins (not) paradox".

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It's conceivable that astronomers all over at least the local area of our observable universe are watching the highly unstable star Eta Carinae and waiting for it to go bang. Which should give us all a really nice fireworks display. (I have a small hope but possibly in vain).

Not one of them, whatever their distance and relative speed to Eta Carinae or anything else; whether they're observing from an orbit within an event horizon; whether they have a long garishly coloured scarf and call themselves Doctor; even if they're boldly going where none have gone before; will see this event run backwards.

The Second Law will not be denied, and all observers shall see order beget chaos.

It all springs from there.

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It's conceivable that astronomers all over at least the local area of our observable universe are watching the highly unstable star Eta Carinae and waiting for it to go bang. Which should give us all a really nice fireworks display. (I have a small hope but possibly in vain).

Not one of them, whatever their distance and relative speed to Eta Carinae or anything else; whether they're observing from an orbit within an event horizon; whether they have a long garishly coloured scarf and call themselves Doctor; even if they're boldly going where none have gone before; will see this event run backwards.

The Second Law will not be denied, and all observers shall see order beget chaos.

It all springs from there.

Backwards is against causality, it is not under discussion.

My question arises from a diagram I have seen about the twins but I don't want to post it here and derail further the discussion.

When two observers are in relative motion, each considers the other to have slower time. That's what puts the (apparent) "paradox" in the "twins (not) paradox".

Yes, that is my understanding too.

Relative to whom?

Since time is relative, this is a simple yes. When measured across two observers, it will have sped up for one and slowed for the other... relatively speaking.

I don't think so. Both will see it the same way. In the examples I know, both observers see the other one as time delayed.

My question is: are there examples where time speeds up?

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!

Moderator Note

michel123456, I believe you have asked questions along these lines elsewhere. Please do not drag this thread off topic with the same ones.

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I stand corrected. Thanks for the update pzk and michel

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I have to agree that if the documentary explained it in just the way they describe, they did a poor job in doing so. The explanation seems to concentrate on the Doppler effect, which in of itself is not the cause of time dilation.

However, we can use what we see to show that the time on the tower clock will actually run slow as measured by the train observer.

If we work out the math, it turns out that, as seen from the train, the tower clock will be running at a rate of

$\sqrt{\frac{1+ \Beta}{1- \Beta}}$

when compared to his own, where Beta is v/c and is positive when the train is moving towards the tower, and negative when it is moving away.

Thus if the train were moving away from the tower at 0.6c, it will see the tower clock run at a rate of 1/2 its own clock. (for every 2 sec that tick off the train clock it will see 1 sec tick off the tower clock.) Now this does not mean that the tower clock actually ticks 1/2 as fast as the train clock, because some of this is due to the increasing distance between clock and tower.

But now let's consider what happens if the train suddenly reverses direction and heads back towards the the tower. Now it will see the tower clock run at a rate 2 times as fast as its own.

So let's say that the train travels for 1 hr away from the tower, then turns around and travels back at the same speed.

For the first half of the trip, it will see the tower clock tick 1/2 as fast and thus sees it read 30 min when the train reverses direction. Then for the 1 hr of the return trip, it will see the tower clock run 2 times as fast and sees it accumulate 2 hrs. This means that during the whole trip, the train sees the tower clock accumulate 2 hr 30 min while its own clock accumulates only 2 hrs.

This means that when the train returns to the tower, it will find that the Tower clock will have advanced 1/2 more than its own.

If we now consider things from the perspective of the tower, we find the following:

As the train recedes, the tower sees the train clock run slow by a factor of 1/2. Since we have already established that the train does not reverse direction until its own clock reads 1 hr, this means that the tower doesn't see the train turn around until its own clock reads 2 hrs. (Because of the distance between train and tower when the train reverses direction, the tower does not "see" the train reverse direction until after the train has actually reversed direction and is already on its way back.

Now the tower sees the train clock run at a rate 2 times it own. But since the train as already on its way back by the time the tower even saw it turn around, the train arrives only 1/2 hr later by his clock, during which time the tower sees the train clock accumulate 1 hr. So by the tower clock, 2 1/2 hrs pass between train leaving and returning while it sees 2 hrs pass on the train clock.

Both tower and train agree that the train aged 1/2 hr less during the trip.

Concerning the bold part: how is that possible?

You are seeming to say that the train is already on his way back. Thus the train is in-between the tower and the point where he turned back. Thus the train is an obstacle to its own image that comes from behind him... or do I understand badly?

Edited by michel123456
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Concerning the bold part: how is that possible?

You are seeming to say that the train is already on his way back. Thus the train is in-between the tower and the point where he turned back. Thus the train is an obstacle to its own image that comes from behind him... or do I understand badly?

It simply means that the image which carries the information that the train has turned around has not reached the tower yet. It left the train the instant it turned around. (When the tower clock read 1.25 hrs).

The light heads back at c, and the train at 0.6c The image is always ahead of the train. Since the train was 0.75 light hrs away when it turned around, it will take 0.75 hrs until the this image reaches the tower. The train will have traveled 0.45 light hrs closer to the tower by then. when the image reaches the tower, the train is 0.8 light hrs distant.

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It simply means that the image which carries the information that the train has turned around has not reached the tower yet. It left the train the instant it turned around. (When the tower clock read 1.25 hrs).

The light heads back at c, and the train at 0.6c The image is always ahead of the train. Since the train was 0.75 light hrs away when it turned around, it will take 0.75 hrs until the this image reaches the tower. The train will have traveled 0.45 light hrs closer to the tower by then. when the image reaches the tower, the train is 0.8 light hrs distant.

I understand now. The train is chasing its own image.

Does that mean that the photons that carry the train's image are like arrows that the train could eventually get very close too only by increasing its speed? IOW that for outwards photons, the relative velocity is not c? and that simple velocity subtraction is allowed?

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I understand now. The train is chasing its own image.

Does that mean that the photons that carry the train's image are like arrows that the train could eventually get very close too only by increasing its speed? IOW that for outwards photons, the relative velocity is not c? and that simple velocity subtraction is allowed?

The train sees the photons leave at c. In other frames, you have the train "chasing" the photons, but they will always outdistance it.

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A lot of reading since my last post,

** Observer(A) - Train - Train Image/frame - Distance to cover - Observer(B) **

while the train cannot possibly move at c, the trains image or frame can. So the distance between the train and it's frame gradually increases/decreases over distance covered. depending on whether or not the train is moving toward or away from the point of observation.

So to the observers witness a trick of the eye, since our eyes / instruments can only measure at a maximum of .999% /c ? an illusion rather than actually dilation of time.

have I got this right? or do I need further instruction?

Edited by Reaper79
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have I got this right?

No. Completely garbled.

while the train cannot possibly move at c, the trains image or frame can.

The light from the train moves at c. As measured by the people on the train. And as measured by us.

The train's frame of reference always travels with the train. That is the definition of a frame of reference - where the train is stationary.

So to the observers witness a trick of the eye, since our eyes / instruments can only measure at a maximum of .999% /c ? an illusion rather than actually dilation of time.

We have instruments that can measure thing moving at the speed of light. Like, you know: light.

So time dilation is not an illusion. It is a real effect that we exploit or take account of in technology.

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Maybe this will help:

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I understand now. The train is chasing its own image.

Does that mean that the photons that carry the train's image are like arrows that the train could eventually get very close too only by increasing its speed? IOW that for outwards photons, the relative velocity is not c? and that simple velocity subtraction is allowed?

You lost me at "outward photons." Which ones are they, may I ask?

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Thanks for the video, but that's not quite what I was asking, I'll attempt to lay down a scenario to illustrate where I am getting stuck

**

The train is a massive object, and cannot move at 100% c

The light reflected from the train can travel at 100% c

The observer can measure light at a maximum of 100% c

Observer A can watch the train depart at 100% c

Observer B can watch the train arrive at 100% c

The trains maximum velocity is 50% c (for arguments sake)

**

which triplet has aged more when the train has completed its journey, Observer A, Observer B, or the Train driver?

Or,

When the train comes to a complete stop, do all the triplets remain identical in age? or has one of them dilated time to become younger or older than the other two?

EDIT: I do understand the frame of reference concept, but I can't see it making a difference once all is said and done, once the train is stopped and the train driver shakes hands with observer B, my puny little mind can't conceive any extraordinary aging by any of the people involved. why should the speed your traveling make you age faster or slower than anyone else?

If all three people remain the same age after the experiment, then no time travel or time dilation could of occurred

Edited by Reaper79
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Thanks for the video, but that's not quite what I was asking, I'll attempt to lay down a scenario to illustrate where I am getting stuck

**

The train is a massive object, and cannot move at 100% c

The light reflected from the train can travel at 100% c

The observer can measure light at a maximum of 100% c

Observer A can watch the train depart at 100% c

Observer B can watch the train arrive at 100% c

The trains maximum velocity is 50% c (for arguments sake)

I assume you are describing the situation where the train travels from A to B. Are A and B stationary relative to one another (i.e. in the same frame of reference)? Most of the information you provide is not very relevant.

Assuming the answer to that is yes, then the train starts in the same frame of reference as A, accelerates then stops back in the original frame of reference. In which case, this is exactly the twins paradox described in the video.

When the train comes to a complete stop, do all the triplets remain identical in age? or has one of them dilated time to become younger or older than the other two?

You are mixing up two things here.

Time dilation: when the train is moving at a constant speed relative to A and B, then A (and B) will see the trains clock running slow. Also, the train will see A's (and B's) clock running slow. (After taking Doppler effects into account.)

Elapsed time: the train has been on a round trip from the frame of reference of A (and B) to an accelerated frame and back again. Therefore, the train will have experienced less elapsed time than A and B.

my puny little mind can't conceive any extraordinary aging by any of the people involved. why should the speed your traveling make you age faster or slower than anyone else?

Why? Because that's the way the world works. The speed of light is invariant.

And this has been tested experimentally so it is not some weird science fiction idea.

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But I would like an answer to my EDIT "If all three people remain the same age after the experiment, then no time travel or time dilation could of occurred " is this statement true or false?

IF A + B + Train Driver, all = same age after the experiment is concluded. Then has anything really happened?

PS: I know your going to beat me over the head with the math again *Smiles shyly* but if it's possible to limit your reply in the form of a thought experiment, I will yield to my betters and drop the argument.

Thanks for being direct, I value all the comments left on this thread.

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IF A + B + Train Driver, all = same age after the experiment is concluded. Then has anything really happened?

Sorry, I thought I had: less time elapses on the train. In other words the train driver will have aged less than the others.

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