When a photon is released, which way does it head?

[tar]

Strange,

 

But if she experiences the same number of ticks of the pulsar, what would cause her to age less?

 

What is the boundry between her and reality, caused by her containment on the moving ship?

 

GR requires forshortening and such to explain what the stationary twin sees of the traveler and what the traveler sees of the stationary. But what does the observer on the pulsar see? Is not the traveling twin within his view, the whole time? Is it not, from the pulsar's perspective, just one time, that both twins existed in, during the trip? Now there is the small issue, that the observer on the pulsar will not witness the trip for 10s of thousands of years, but when he does, there is no moment in time when both twins are not concurrently existing.

 

On the tangent thing. Let's say the traveling twin was going tangent to the pulsar at the halfway point.

 

Regards, TAR

Half way to the turn around point.

[Strange]

But if she experiences the same number of ticks of the pulsar, what would cause her to age less?

 

She experience less time. (Which is why, on average, she must see the ticks from the pulsar happen more quickly.)

 

 

GR requires ...

 

Actually, this can all be described with special relativity (which is good as the mathematics is pretty simple).

 

 

But what does the observer on the pulsar see? Is not the traveling twin within his view, the whole time? Is it not, from the pulsar's perspective, just one time, that both twins existed in, during the trip?

 

The pulsar is (I assume) in the same frame of reference as the twin on Earth (i.e. not moving significantly relative to Earth). Therefore an observer on the pulsar will see the same as the observer on Earth. (Otherwise you are introducing a third frame of reference which just makes the whole thing needlessly complicated.)

 

There is no "just one time".

 

 

On the tangent thing. Let's say the traveling twin was going tangent to the pulsar at the halfway point.

 

This is equivalent to the travelling twin heading towards the pulsar then turning round and heading away from it. This is all explained in great detail on the Wikipedia page for the twin paradox. I honestly don't think I can do it better or simpler. (The twins will, of course, disagree about when the halfway point occurs.)

Edited September 1, 2014 by Strange

[tar]

Strange,

 

There is no "just one time".

 

Well, I suppose this is true...except I noticed a handful of years ago, that everybody in the room I was in, was experiencing the same now as I was. That is, everybody aware of anything at the moment is aware of the same moment as I am. Putin just said whatever he just said...for everybody on the planet.

 

Combine this fact, with the fact that the Mars probe was 14 minutes away, and one has to both agree that there is not just one time, in the one sense, and that there is just one time in the other sense, that every item in the universe must be 13.8 billion years old, and in this manner experiencing the same "tick", currently.

 

This is not a paradox, it is the reality of the situation. A dual requirement, the same as when two people stand next to each other, the other is alternately on the left and right.

 

My take, anyway, that a focal point, such as a human (could be any item) is always at the longest time from the start as is possible. That is, everything that exists, exists currently, and everything that exists is connected to everything else that exists, at the speed of light.

 

There is no other current item that you can experience but in the two ways you experience it. 1. When you see it. 2. When you imagine it, or figure what and when it had to be doing before now, to look that way now, and concurrently imagining what that means for where that item is and what it is currently doing.

 

The equations of relativity express these relationships in a clear and concise manner, and the users of the formula know which stance one is taking and what is relative to what. When it is imagination, and when it is sense.

 

But a couple years ago, I remember looking at the moon, and considering that without a doubt, it was here, now. I know it is separated from me by a distance that it would take light to travel, but I did not have to wait it. There was and is no way for me to experience the moon any more currently than now. If I was to travel to it at the speed of light it would take me exactly the time to get from here to there, as it takes light to get from it to here. In that time the moon would have gotten that much older, and when I got there, it would be doing exactly what the moon is currently doing.

 

If one would travel to a distant quasar at the speed of light, it would not be a quasar when one got there, as quasars are a thing of the past. It would be a galaxy of stars perhaps similar to ours.

But, the photons coming from the quasar would have to be accounted for as you traveled toward it. Billions of years worth of emmisions, you would be running into. The photons would be blue shifted and the frequencies so high as to be destructive or at least something that we don't know the physics of. You would experience the whole evolution of that quasar, into whatever form it currently holds, during your trip, and it would...wait...into whatever form it will hold in the time it takes you to make the trip, from now. You would "run into" what it actually looks like now, when you were about halfway there, and by the time you got there, it would actually have had that time to evolve further than how it stands today.

 

So, no, there is not just one time. But on the other hand, there probably is. That, being now.

 

Regards, TAR

[Strange]

Well, I suppose this is true...except I noticed a handful of years ago, that everybody in the room I was in, was experiencing the same now as I was. That is, everybody aware of anything at the moment is aware of the same moment as I am.

 

You were all in the same frame of reference, that is why.

 

However, if some of those people lived high in the Andes or Himalayas (or even up a small hill) they would disagree very slightly about how much time had elapsed since you were all in the same room together a year before.

 

Combine this fact, with the fact that the Mars probe was 14 minutes away, and one has to both agree that there is not just one time, in the one sense, and that there is just one time in the other sense, that every item in the universe must be 13.8 billion years old, and in this manner experiencing the same "tick", currently.

 

Quite the contrary. The Mars probe is moving and n a different gravitational potential to us. Therefore it is experiencing a very slightly different time. This is probably small compared to the Doppler effect but it would probably be possible to measure the difference in the frwquency of its radio signals sent and received, due to relativistic effects.

 

My take, anyway, that a focal point, such as a human (could be any item) is always at the longest time from the start as is possible.

 

That is only true in special relativity. That symmetry breaks down when you take gravity into account.

 

That is, everything that exists, exists currently, and everything that exists is connected to everything else that exists, at the speed of light.

 

And that is exactly why there is no universal or absolute time.

 

The equations of relativity express these relationships in a clear and concise manner, and the users of the formula know which stance one is taking and what is relative to what. When it is imagination, and when it is sense.

 

Then why are you contradicting them?

 

But a couple years ago, I remember looking at the moon, and considering that without a doubt, it was here, now. I know it is separated from me by a distance that it would take light to travel, but I did not have to wait it.

 

1. Time runs at a different rate on the moon.

 

2. If the moon exploded you would have to wait 1.2 seconds to find out.

 

So, no, there is not just one time. But on the other hand, there probably is. That, being now.

 

Just plain wrong.

 

Edited September 2, 2014 by Strange

[tar]

Strange,

 

I do not so much think I am contradicting, as I think I am suggesting an additional way to look at the problems.

 

That is, when one gets carried away by trying to bind together the image of two frames of reference, separated by a distance that it would take light to travel (which is any distance), sorting out the "from which frame are you viewing" is difficult, and the imagination tends to try and take an overall view, that sees the two frames, at the same time, with instant positioning between the two, that puts them again relative to each other, a certain distance apart at an appointed "time". This is very hard to manage, as they are "off" from each other due to their acceleration and velocity, and agreeing on an observer that can see them both at once, is hard and subject to definitional misunderstanding. However, the pulsar will not lie, and any frame you choose, moving or stationary, high in the Andies or at the bottom of the sea, on Mars or Earth, will be on a particular count of pulses from that pulsar, starting from the first pulse that pulsar pulsed. The different positions and accelerations will be on differenet counts, according to their relative positions from each other, and their relative motions toward and away from the pulsar relative to each other. But should they be in the same spot, in the same frame of reference again, not moving relatinve to each other and exactly the same distance from the quasar, they can not but help to see the exact same pulse from the quasar.

This gives one (me) a standard to go by. Something to add back the various claims of time dilation and measurement and such, and figure what is "meant" by the claims. Gives me something to judge the "lengths" of the ticks of various clocks against, and that is the existence of all the ticks of the pulsar, existing currently in the space between the pulsar and us, and in the space in the oppostie direction of the pulsar, as well. The tick of the pulsar that we experienced one second ago has just "gone by" us, at the speed of light. If we were to follow it, and try to experience it again, we could not. Yet an observer 186,000 miles away from us, will see that tick right now. If we were to travel the 186,000 miles and talk with said observer, when we got there, we would be on the same count again. Whatever happens on our trip, would have to jive with the pulsar's beat, and we can never "catch up" to a beat in reality, as we can outrun the thing, in our imaginations.

 

Regards, TAR

Edited September 3, 2014 by tar

[Strange]

That is, when one gets carried away by trying to bind together the image of two frames of reference, separated by a distance that it would take light to travel (which is any distance), sorting out the "from which frame are you viewing" is difficult, and the imagination tends to try and take an overall view, that sees the two frames, at the same time, with instant positioning between the two, that puts them again relative to each other, a certain distance apart at an appointed "time".

 

That is probably why you are getting so confused. It is more productive to just stick to what the theory really says.

 

 

This gives one (me) a standard to go by. Something to add back the various claims of time dilation and measurement and such, and figure what is "meant" by the claims. Gives me something to judge the "lengths" of the ticks of various clocks against, and that is the existence of all the ticks of the pulsar, existing currently in the space between the pulsar and us, and in the space in the oppostie direction of the pulsar, as well.

 

Unfortunately, your imagination is giving you the wrong answer.

 

 

If we were to travel the 186,000 miles and talk with said observer, when we got there, we would be on the same count again. Whatever happens on our trip, would have to jive with the pulsar's beat, and we can never "catch up" to a beat in reality, as we can outrun the thing, in our imaginations.

 

And if that is so, then the two of you will have experienced a different time between the pulses.

[tar]

Strange,

 

Hum. I suppose you are right, that they would each experience a different time between the pulses, but that can easily be understood as redshift and blueshift of the wavelengths, and not as dilation of time itself. I suppose, for me, I would rather keep something constant, like the ticking of the pulsar and move everything else around within that structure. I don't feel confused doing such. It makes perfect sense to me.

 

Regards, TAR

[Strange]

Hum. I suppose you are right, that they would each experience a different time between the pulses, but that can easily be understood as redshift and blueshift of the wavelengths, and not as dilation of time itself.

 

Time dilation is in addition to any Doppler effect.

[tar]

Strange,

 

In addition to? Does that not require first having the doppler effect considerations already accounted for, completely?

 

Struck me, a while back, that from my perspective, everything else that is happening now, will "get to me" later, because of the speed of light limit that connects one event with another. The "photons" that this thread is attempting to "keep track" of. Near stuff, right away, and one can move on to expect the next thing happening...the one thing done, and in the past, and the next true thing occuring. However, there is a different kind of consideration, when a thing is more than a moment away. The question rose in my mind, "which is true?"...that which you see, or that which must have happened for what you see to be happening, or that which must be happening now, for you to see it happening later? The corallary question is, how many instances of a thing are there? Is there only one instance of a thing, or not? Most evidence points to the fact that there is only one instance of a thing. You, for instance are only where and when you are, right now, even though you have been all those other places you have been, in all those other moments. And in general, within the slop of a couple second long moment, we are all IN the same moment, those of us on Earth. But the Mars rover, is in a different one. Has to be in the same one, in certain senses, and has to be in a different one, in other senses. This difference is, in a majority way, due to the distance between, that it takes light to travel the span. It is only forteen minutes, so one can add and subtract, back and forth and take each perspective and decide what is "really" happening "now", and what is a delayed image.

 

But in a galaxy 250 million lys from here, the separation is massive. You can not switch back and forth and have a good idea of what is "really happening now" and what is delayed image. Especially because of the size of the galaxy, where what you see on the fringes happened a longer time ago, than what you see at the closest part of it. You have to be calling similtaneous, that which is not in actuality happening anywhere close to "at the same time". So if you are concerned with the apparent rotational speed, not jiving with physical laws, my question is, "have you properly taken into consideration, the size of the thing you are looking at, and the fact, that the whole thing, even though it looks tiny from here, is not, and is not happening all at once, as it appears from here, to be happening?."

 

Regards, TAR

And it seems rather wrong to me to make statements like "the expansion of the universe is accelerating" based upon old, older and even older images of what the universe already did...with NO way to actually check on what its doing now. We do not even know how the Mars rover is doing right now, until forteen minutes from now.

Was watching Star Trek the other day, and the craft was moving through the stars like one would move through falling snow. It would not look like that. You can not go 8 times the speed of light, to begin with, and if you could, things would certainly "look" different than that. Things you where heading toward would be blue shifted impossibly much, and things behind, redshifted impossibly much.

 

Saw a rendering of our universe on the web a while back, where the observer, is moving through galaxies and walls and strings of galaxies. Really? What speed is that observer traveling? And if that imaginary perspective were to be taken, would we not see galaxies evolve as we approached them? Would be not see them sped up in their motions? Would we not see them get larger and larger as we approached, until we were "in them"?

 

I maintain, that having an "image" of what the universe currently "looks like", which differs from what it actually looks like, is useless at best. False at worse.

Edited September 5, 2014 by tar

[Strange]

In addition to? Does that not require first having the doppler effect considerations already accounted for, completely?.

 

Effectively, yes. There will be a Doppler effect due to the object moving towards/away from you. As well as that there is relativistic time dilation.

 

Struck me, a while back, that from my perspective, everything else that is happening now, will "get to me" later, because of the speed of light limit that connects one event with another.

 

Of course.

 

The question rose in my mind, "which is true?"...that which you see, or that which must have happened for what you see to be happening, or that which must be happening now, for you to see it happening later?

 

All of them? None of them? It depends how you define "true". But that is a philosophical discussion, nothing to do with science.

 

But in a galaxy 250 million lys from here, the separation is massive. You can not switch back and forth and have a good idea of what is "really happening now" and what is delayed image.

 

This is why science and maths trump imagination.

 

Especially because of the size of the galaxy, where what you see on the fringes happened a longer time ago, than what you see at the closest part of it. You have to be calling similtaneous, that which is not in actuality happening anywhere close to "at the same time". So if you are concerned with the apparent rotational speed, not jiving with physical laws, my question is, "have you properly taken into consideration, the size of the thing you are looking at, and the fact, that the whole thing, even though it looks tiny from here, is not, and is not happening all at once, as it appears from here, to be happening?."

 

I am still waiting for you to demonstrate that this is significant.

 

And it seems rather wrong to me to make statements like "the expansion of the universe is accelerating" based upon old, older and even older images of what the universe already did...with NO way to actually check on what its doing now.

 

And this is why science and maths trump imagination.

 

Was watching Star Trek the other day, and the craft was moving through the stars like one would move through falling snow. It would not look like that. You can not go 8 times the speed of light, to begin with, and if you could, things would certainly "look" different than that.

 

You do realise it is fiction? For entertainment purposes?

 

I maintain, that having an "image" of what the universe currently "looks like", which differs from what it actually looks like, is useless at best.

 

And this is why science and maths trump imagination.

[tar]

Strange,

 

There was a promo picture for that British Butler show set in the early part of the twentieth century with two of the characters standing in front of a fireplace, with a plastic water bottle on the mantle.

 

You can get fiction wrong.

 

I am sorry, you are right, I have not yet shown the significance. I forgot I was working to that end. Well didn't really forget, I am working on the components, trying to get the definitions straight in my mind, of when we consider something happening now, and when we know it happened earlier, and so on.

 

One "thread" I am working on, is the "numbering" of the pulses a hydrogen atom has undergone/expressed since the beginning of the universe. I realize these are not regular pulses, like some hyperfine transition of cesium or something, and are contigent upon the absorbtion and reemission of energy which may well happen at different random rates for two different atoms, and be related to the proximity of an atom to another, as well as the type and number of surrounding atoms, but the idea of the count, or a hydrogen atom being the exact same age (the age of the universe) as another atom, I am using as a vehicle to imagine the difference between what is happening at the close part of a distant galaxy and what is happening at a more distant part.

 

It is hard to tell the difference between a spectral line made by pulse number 12345.....234 and pulse number 12345...237.

The difference is about the same as the difference between pulse 12346..234 on one atom and 12345...234 on the other, especially if it represents the same transition. Even though the two events could have been separated by billions of years.

 

In the case of the galaxy, any tilt of the galaxy, from being exactly normal to our eye view, would create vast time differences, in terms of the age of the hydrogen atom at the close point, and one on the fringe.

 

Having an equation, that considered these two points happening at once, based on which of these (numbered) pulses are reaching our eye now, would be somewhat suspect if it did not include the difference in age of the pulses. And somewhat complex if it did. Leading me to believe that either this difference is not taken into account, or that it is neglected and dropped, inappropriately.

 

The doppler affect you say has to do with the relative motion toward or away from us, that a light emitting object is or has taken. Perhaps this is NOT the effect that I am saying needs to be factored into the equations. What I need to be factored in is the distance in both time and space that exists between one part of the image and another, and the distance in time and space between us and the object's closest point.

 

Regards, TAR

[tar]

An image we hold in our head, of a galaxy or a cluster of galaxies, is "taken" from a particular vantage point, other than the one the Earth currently holds.

 

If we model the "local" super cluster and visualize it all at once, especially with us in the picture, we are suggesting that all and each of the shining objects in the picture are there now, in that particular arrangement. In our heads we can rotate the model, and the items would maintain their geometric relation to each other, in terms of vectors and lengths, imagined on a three dimensional grid of cartesian coordinates.

 

However, it is not claimed or defined that the items thusly positioned have been temporalized, that is, that any two items pictured in the model are of the same age, and were, are or will be at that spot, at a particular imagined moment. This unclear definition is as bad as the plastic bottle on the early 20th century mantle, because you can not see the current position of the strings of galaxies that the Milky Way is a part of, "at the same time", in any manner different from the way we actually see it all, from here. One photon at a time.

 

Looking in a particular direction, at a galaxy and implying galaxy size movement from the recessional velocities figured by the spectral lines, of material in that direction, only gives us toward and away from us, information. We do not particularly know if that particular photon we collected came from the nearside, the middle, or the back of the column of the galaxy that we are figuring it came from. We do not particularly know if the atom that emitted the thing was going left or right, or up or down at the time, and we can only figure it was in that particular direction we are getting the photon from, in a 50,000 year long window, and that window occurred some 250,000,000 years ago.

 

If we were to "look at" the galaxy in question from an observation point directly in our line of vision, but only 50,000,000 lys away from, it, right now, all the stars in the galaxy would be in different positions than the positions we currently witness. They would all be older, 200,000,000 years older than what we see, and would have had 200,000,000 million years to move around, get closer to or farther away from the center, increased or decreased their distance from neighboring galaxies, blown up or evolved, gained material or lost it, in the interim.

 

But you, Strange, claim that the 50,000 ly decrepancy between the front and back is too small a percentage of the distance between us and it, to make a difference in our calculation of the speed of rotation of a star around the center of the thing.

 

And I have to prove that it would matter.

 

Perhaps this thought experiment would show it would make a difference. Establish an observer 250million lys on the other side of the galaxy in question, exactly as far away as us, from the center of the galaxy in question. Plot the position of each noticable item in the galaxy from here. Plot the position of each noticable item in the galaxy from the other observation point. The items will be at different points, and the galaxy in a different percieved arrangement, from the two vantage points.

 

Regards, TAR

[Strange]

Perhaps this thought experiment would show it would make a difference. Establish an observer 250million lys on the other side of the galaxy in question, exactly as far away as us, from the center of the galaxy in question. Plot the position of each noticable item in the galaxy from here. Plot the position of each noticable item in the galaxy from the other observation point. The items will be at different points, and the galaxy in a different percieved arrangement, from the two vantage points.

 

You could work out exactly how different the positions seen by each observer would be (*). From that, you should be able to show whether or not the difference was significant.

 

Of course, we would have to agree what "significant" means, in advance. I would suggest "larger than the measurement error in their measurements".

 

(*) I don't expect you will, though.

[physica]

 

You could work out exactly how different the positions seen by each observer would be (*). From that, you should be able to show whether or not the difference was significant.

 

Of course, we would have to agree what "significant" means, in advance. I would suggest "larger than the measurement error in their measurements".

 

(*) I don't expect you will, though.

I think Tar's problem here is that he isn't using maths. Now this isn't the end of the world but words have multiple meanings making it harder to communicate. Combine that with Tar's waffle style of writing and you get a lengthy post that's fairly useless.

[tar]

Strange,

 

I am working on it, but it is difficult to find the right baseline.

 

There seems to be two nows. I talked about this before I know, but it is crucial to the figuring.

 

I am rather sure there is only one instance of a particular thing, that is what makes it a particular thing, but each thing is in a particular position in relationship to everything else. Deciding what is true about an item 3 lys from here is an interesting conundrum. It is really there, now, doing something, just one instance of the item currently extant. It has a definite history and will have a definite future, and will at all times, past present and future be just one particular item...but, we are looking at the darn thing, like it is here, now, which it actually is, in the most immediate way that the universe can present itself to other parts of itself.

 

So for the galaxy in question that we are looking at from here, and from exactly as far away from the center of it, in the other direction, we have some interesting "time" shifts to engage in, and sort out in a manner that does not create any paradox.

 

To do this, we (I) have to entertain the thought that there are two types of now to consider. One is an actual now, that exists for any "living" observer, as the present moment, which is made up of the historical information arriving continually from the rest of the universe. The other "now" is an imaginary consideration of the entire universe consisting of only the present moment, where every "living" observer is 13.8 billion years old. This type of consideration demands that what we see as Cosmic Background Radiation is historical information from shortly after the big bang, having eminated from a very distant section of our universe, which is currently 13.8 billion years old. Which now you consider real and which you consider imaginary, can change hands, depending only on which way you are looking at it. We can not ever actually see it all at once, and have to peice together our image of what it has to be really like, in our imaginations.

 

So the calculations might not be difficult, but setting up the problem is hard because you have to be careful to choose, at the beginning, a reference point in time and space, that you will consistently refer to, throughout the entire calculation. This is hard for my brain to handle, in terms of the constant check backs, to make sure I am doing it right, and not forgetting that it takes light time to get from one place to another, and constantly assess the nature of my perspective, so that I do not inappropriately consider two things simultaneous in one manner, when the other is the appropriate manner in which to consider it, for the benefit of the calculation. After all, the distance between real objects takes time to traverse in the one sense, and can be transversed instantly in the other.

 

Regards, TAR

 

besides, you only figure I won't be successful in accomplishing the calculation because you can see what a challenge it would be to maintain the correct perspective at the appropriate points

[Strange]

 

The other "now" is an imaginary consideration of the entire universe consisting of only the present moment, where every "living" observer is 13.8 billion years old.

 

There is no "universal now".

[tar]

Strange,

 

I require there to be such, inorder to make sense of everything.

 

How can you say there is not such a thing?

 

Right now, the closest star to us is shining. We know this has to be the case, because the thing is a distance away, light takes time to travel, and we saw the thing yesterday, we see it today and we will see it tomorrow. Therefore there must be photons on their way here now, and photons that passed us, on their way somewhere else. ALL places in the universe must be, in actually, now, 13.8 billion years old, because everything came into existence 13.8 billion years ago. This establishes very firmly, with no question about it, a "universal now". That which is the case, presently, everywhere.

 

On the other hand, we see very distant things as very young things, on millions of years old or only 10 billion years old, or whatever. Whatever age an observer is, is the age of the universe. Everything else is the same age, but is observed as being younger, because it took light some time to reach the eye of the observer. This would be the case if the thing was a billion lys away or a million, or one, or a million miles or a mile or a meter or a nanometer, or a planck distance, away.

 

Regards, TAR

[Strange]

I require there to be such, inorder to make sense of everything.

 

That is not how science works. You have to try and make sense of what is, not try an impose your wishes on reality.

 

How can you say there is not such a thing?

 

Sounds like you need to learn about a little thing called the "theory of relativity".

[tar]

Strange,

 

I've heard of that.

 

I have a book on the arm of my chair, right now, entitled The Principle of Relativity. It is a collection of original papers on the special and general theory of relativity by Einstein, Lorentz, Weyl and Minkowski. I have actually read every word and thought about the ideas and implications.

 

I consider similtaneity and what it would require. I am not in complete agreement when experiments call a thing simultaneous and then change the defintions, midstream. You should not have to shorten stuff to make your equations work.

 

In the train experiment, with the lightning strikes at the front and rear of the train, happening similtaneously from the vantage point of the guy on the embankment, the actual photons from the one strike and the other are reaching him at a particular moment. The train rider is presumably directly inbetween the two strikes, at this moment, so the first photons from the left hand strike, and the first photons from the right hand strike will arrive at this central position, together. At the same time, even though the time is slighly after the strikes themselves. Perhaps the guy on the embankment was closer to the strikes and saw them first, or further from the strikes and saw them after, but because they have already been stipulated as being simultaneous, any position on a plane imagined directly between the two strikes, will experience the first photon from each, at exactly the same time. One strike will not occur before the other, no matter how fast, in what direction they are proceeding, as long as they are in a position on that plane, when they experience the first photon from the one, they have to experience the first photon from the other, simultaneously. What will be different between the guy standing on the embankment and the observer in the train, is the frequency of light they see, or if you will, when they experience the second photon from each. There will be a shorter amount of time until the second photon from the right strike reaches her, because she is traveling toward it, and will experience a bluer light. The strike from behind will be redder. Her train will not shrink when measured in the direction of movement, because she is moving. It has no reason to shrink.

 

So if all of relativity stands on the fact that she will see the lead strike before the trail strike, I just don't agree. Because by definition, she needs to see the first photon from each strike simultaneously. You can not say the strikes are simultaneous and then say, "well no, there is no such thing".

 

There is a universal now. And that is what is currently happening at every position in the universe. When we see it, will be exactly coincident, with how far away it was when it happened and how fast we are moving toward it, or away from it in the interim. That is, imaginarily, every position in space has some particular collection of photons, in and around it, and each of those photons is on its way to some other position, at the speed of light. Historically you have to account for a particular photon, and where it was and where it is going at a particular time. Whether that time is past present or future, does not change its starting point and time, nor the course it flew or will fly.

 

I am offering an alternative way to look at what must be the case. I am not suggesting the world is any different than we experience it, or measure it.

 

Regards, TAR

The guy standing down the track to the right will see the right hand strike first and the lefthand strike after, because he is closer to the right hand one, then the left. In this case even two observers in the same frame of reference will not agree on the order of the strikes, or on their similtaneity. I am counting on that to be the case, because the universe is not all at the same place and time.

It is all happening now, at different places, and its all arriving here presently, both. It can not just be one way or the other. That would not look the way that it does. It has to be the way it actually is, to look like this.

(meant closer to the one than the other, wrote "then", but am having trouble with my edit)

[Strange]

 

So if all of relativity stands on the fact that she will see the lead strike before the trail strike, I just don't agree.

 

All of relativity does not depend on this. It is a consequence of relativity.

 

I have wasted too many hours trying to explain this very simple thought experiment to people who refuse to understand it. I am not doing it again. If you don't understand it, that is your problem, not relativity's.

[tar]

Strange,

 

Relativity is not a person. It does not have problems.

 

I can have a problem with other peoples concept of it, as other's can have a problem with mine.

 

General relativity and special relativity are two different concepts with two different purposes, designed for each purpose by humans.

 

Any beef I would have with a concept is therefore with the concept holder, not with the thing that the each of us is conceiving.

 

Regardless of which aspects of relativity you get and I do not, the two lightning strikes were similtaneous to all positions in the plane between them, and NOT to each other. Light takes time to get from one place to another. The lightning strike on the right, was not seen by an observer at the position of the left lightning strike immediately and similtaneously. The observer AT the left strike saw the other strike, after it saw its own.

 

Show me where such a thought is wrong,

 

Regards, TAR

So,

 

It would be required, in the thought experiment to be consistent with what we are calling the lightning strike, and its duration.

 

If we are concerned with the midpoint, in terms of the duration of the strikes, lets say they each were a second long, then the traveler will experience the midpoint of the right hand strike, prior her experiencing the midpoint of the lefthand strike, but if this is what you are concerned about, you can not talk about WHEN the strikes happened as one instant, because the start of either lightning did not occur at the same time as the end of even its own flash.

 

But in the thought experiment the stipulation is that the two strikes were simultaneous to the guy on the embankment. This stipulation requires that all points that are the same distance from both strikes, see the events as simultaneous. They must by definition start at the same moment for both the guy on the bank and the woman on the train. But the strike on the right will be over for her in a shorter time than the strike on the left, which, if you track the photons, would have to happen like this. The last photon associated with the lefthand strike, will pass by the guy and later reach the woman who is now a greater distance from the left hand strike, then she was when she saw the first photon. The train need not shorten to accomidate this reality, she just sees the light as redder than the guy. and the finish of the strikes was simultaneous to the guy, but not for the woman who saw the right strike's billion blueish pulses finish in slightly less than a second, and the left strike's reddish pulses finish in slightly more.

She must see the same number of pulses as the guy, because those are the pulses the strikes made. If she is running into them they are bluish, if she is going away they are reddish, but this way of looking at relativity, does not require the train to shorten. It makes complete sense without the train shortening.

 

Regards, TAR

Edited September 28, 2014 by tar

[physica]

 

All of relativity does not depend on this. It is a consequence of relativity.

 

I have wasted too many hours trying to explain this very simple thought experiment to people who refuse to understand it. I am not doing it again. If you don't understand it, that is your problem, not relativity's.

I agree don't waste your time strange. This guy has put me on ignore so he doesn't see my posts and accused me of giving him negative votes even though it was multiple people (confirmed by a mod) he still stands to his religion. You can see in this thread here, he actively takes steps not to learn anything. If he doesn't understand it then his religion dictates that it must be wrong as opposed to him.

 

 

Relativity is not a person. It does not have problems.

I can have a problem with other peoples concept of it, as other's can have a problem with mine.

General relativity and special relativity are two different concepts with two different purposes, designed for each purpose by humans.

Any beef I would have with a concept is therefore with the concept holder, not with the thing that the each of us is conceiving.

Poorly written pointless waffle that doesn't really mean anything. If TAR wrote more concisely he wouldn't confuse himself and other as much.

[Strange]

Here is an animation of the thought experiment, which may help:

[tar]

Actually Strange,

 

 

I saw that video up in Physics, before my comments. Its what made me think of it. I have Einstein's own discription of it in a book I just touched. I have read the passage many times over the last decade or two and thought about it a lot. A whole lot. That is WHY I have my photon tracking requirement, and my understanding of simultanaety, because I have read and attempted to grasp what is happening with light, and observers and time and space.

 

Watch the video again. Why do the circles not touch exactly when the woman is in front of the man. They should. Because similtaneity IS when light takes the same time to get to an observer from two distant points. Every time the simulation shows the photons coming from the front and back of the train, whether from the point of view of the moving woman or the stationary man, the circles should touch, right when the woman is in front of the man. If they do not, then the simulation is wrong. It contradicts the initial condition that the strikes were simultaneous.

 

Regards, TAR

[Strange]

I have Einstein's own discription of it in a book I just touched. I have read the passage many times over the last decade or two and thought about it a lot. A whole lot.

 

So I guess it takes a lot of effort to find ways of no understanding something so simple. This also confirms that it is not worth wasting my time attempting to explain to someone who is so determined not to understand.

 

Why do the circles not touch exactly when the woman is in front of the man.

 

Because the train is moving. If you can't even grasp that, there isn't much hope. Even if there were such a thing as universal simultaneity, she would still have moved and so not be in front of the main when the light arrives.

 

Because similtaneity IS when light takes the same time to get to an observer from two distant points.

Exactly. And, for obvious reasons, it doesn't take the same time to get to the observer on the train.

 

 

I thought about this a bit more in the context of your interest in the photon description of things. The train experiment is normally described in terms of the wavefront, but maybe an alternative view will help.

 

Imagine two machines, F and B, on the platform. Machine F fires a single photon at the man on the platform when the front of the train is aligned with it. Machine B fires a single photon at the man on the platform when the back of the train is aligned with it.

 

The man on the platform is half way between the machines. He receives both photons at the same time. He therefore concludes that the two photons must have been emitted at the same time (distance divided by speed).

 

Now consider the situation where the same two machines fire the photons at the woman on the train. She is moving towards F and away from B. She is therefore also moving towards the photon from F as it approaches her. She is moving away from the photon from B as it approaches her. She will therefore receive the F photon before the B photon.

 

She knows both photons travelled the same distance because they were both emitted when the front and back of the train were aligned with the F and B machines.

 

She knows both photons travelled at the same speed (the speed of light).

 

Therefore, the one she received first must have been emitted first.

Edited September 30, 2014 by Strange