Relativity or something [Split from "Pressures"]

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steve waterman
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Re: 1067: "Pressures"

Postby steve waterman » Fri Oct 19, 2012 3:07 pm UTC

ivnja wrote:
steve waterman wrote:If we choose a different reference frame ( move where the origin of the reference frame is )

Right, move the origin....say, at a constant velocity of three quarters the speed of light in some direction. That'd be changing the reference frame. And maybe get one of the receivers going two fifths the speed of light in a different direction. Then how would it work? Who would be seeing one second intervals?


Who would be seeing one second intervals?


Why must you continue to confuse transmission with receipt? It is NOT about who sees, it is about who sends.

THIS IS ONLY ABOUT TRANSMISSIONS, there is no UNIQUE order to receptions, there is for TRANSMISSION SEQUENCE.

Someone talk to me about transmission sequence and stop forcing the conversation to be about any damn receipt sequence.
Someone get on the same page please, and imagine the damn transmissions sequence.

To say there is no transmission sequence, when we have two methods that proved this, is well, - I do have the words to properly express my feelings.
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Re: 1067: "Pressures"

Postby ivnja » Fri Oct 19, 2012 3:16 pm UTC

steve waterman wrote:To say there is no transmission sequence, when we have two methods that proved this, is well, - I do have the words to properly express my feelings.
is fucking moronic, I'm sure.


What you're continuing to not understand is that all you've "proved" is that you can show a unique transmission sequence unders a certain subset of conditions, and that everyone already agrees that there is a unique transmission sequence under that certain subset of conditions. What you have failed to address is anything outside that subset.
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Re: 1067: "Pressures"

Postby Max™ » Fri Oct 19, 2012 3:17 pm UTC

steve waterman wrote:
ivnja wrote:
steve waterman wrote:If we choose a different reference frame ( move where the origin of the reference frame is )

Right, move the origin....say, at a constant velocity of three quarters the speed of light in some direction. That'd be changing the reference frame. And maybe get one of the receivers going two fifths the speed of light in a different direction. Then how would it work? Who would be seeing one second intervals?


Who would be seeing one second intervals?


Why must you continue to confuse transmission with receipt? It is NOT about who sees, it is about who sends.

THIS IS ONLY ABOUT TRANSMISSIONS, there is no UNIQUE order to receptions, there is for TRANSMISSION SEQUENCE.

Someone talk to me about transmission sequence and stop forcing the conversation to be about any damn receipt sequence.
Someone get on the same page please, and imagine the damn transmissions sequence.

To say there is no transmission sequence, when we have two methods that proved this, is well, - I do have the words to properly express my feelings.

How do you determine transmission sequence without observing the signals?

In the same frame as the transmission sequence, there is one observation, in another frame there is another, both are valid.


How is this: if several transmitters in different states of motion sent signals, which ordering would be "right"?
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Re: 1067: "Pressures"

Postby Monika » Fri Oct 19, 2012 3:29 pm UTC

Steve, as you have been told several times in the last few pages:

We are not confused. We are not talked about when light is arriving at the observers. The observers are capable of doing math. The observers figure out from when they see something and where they see it when and where the event happened. For this calculation they take into account that the light is also taking some time to get to them. And observer is a reference frame. It contains two detectors - or if you want four or nineteen. They are able to triangulate where and when the events took place. In the "coordinate system" of the reference frame.

Then there is a second observer = a second reference frame. It is moving in relation to the first one. It also has two (or four or any number of) detectors. It also does triangulation and math and stuff and figures out when and where the event happened, e.g. light was emitted. In its own "coordinate system".

If there were no relativity they would get to the same result. But as there is relativity they do get different results. In some cases even so different that they get different results for in which order the events happened.

Really nobody is talking about the order in which the observers are reached by the light from the event (assuming the event was an emission of light). So stop telling us that we are talking about the reception of light. We aren't.

Example of what we are not talking about:

exploding star (sender) 1 ------ observer/receiver 1 ----------- observer/receiver 2 ----------- exploding star (sender) 2

Nothing is moving, i.e. just one reference frame.
Let's say star 1 explodes first and star 2 a bit later.
They are all very far apart and the light from explosion 1 reaches observer 1, but not yet observer 2 when star 2 explodes.
So observer 1 will see star 1 explode first and then star 2, and observer 2 in the other order.
But each observer/receiver consists of two detectors positioned appropriately to be able to do triangulation. Each figures out how far star 1 and star 2 are away and from this calculate the time it took to get there.
Both observer 1 and observer 2 figure out that star 1 exploded first and star 2 exploded second. Observer 2 knows or "observes" this, too, even though the light from star 2 explosion came there first.

So when we say "observe" we do not mean that the light comes there first - we talk about what the observer can figure out, of the result "after doing the math".
And we don't think that the observers consist of only a single detector, we assume we have enough information for the triangulation for the distance and thus (with the speed of light) the time. Two detectors in each observer should be enough for this.

Again, this example does not show anything about Relativity, because nothing is moving. We have just one reference frame. All observers agree on the time and location of the events.

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Re: 1067: "Pressures"

Postby steve waterman » Fri Oct 19, 2012 3:54 pm UTC

Max™ wrote:How do you determine transmission sequence without observing the signals?


Impossible to determine the transmission site or transmission time without receiving the signal.
Observed on not, determined or not, the transmission sequence never-the-less unfolds in a UNIQUE sequence.
Observing the transmission sequence in a different receipt sequence does not alter the historical UNIQUE transmission sequence.
Neither does not observing any receipt sequence.

In the same frame as the transmission sequence, there is one observation, in another frame there is another, both are valid.


Two observers can but rely on their singular observation, as they cannot EVER figure out the transmission particulars, even sharing their info together. They can agree upon the transmission site as being some unknown POINT from within the appropriate hyperbola. They both remain in the dark, when it comes to knowledge of the transmission sites or transmission times.

ANY 4 sites are needed to receive the transmitted signal in order to be able to know the transmission site and time.
How is this: if several transmitters in different states of motion sent signals, which ordering would be "right"?


At the moment of transmission, the transmission site is a POINT. POINTS are stationary. A receiver going at c/2 receives the signal at ONE POINT. The point is not in motion wrt this particular chosen Cartesian coordinate system.

Just give me the receipt POINTS and their receipt times.
Velocity of sites at moment of transmission or receipt is TOTALLY irrelevant.
I am talking math, points have no velocity in a Cartesian coordinate system.





JudeMorrigan wrote:
steve waterman wrote:If we choose a different reference frame ( move where the origin of the reference frame is )

Steve, you seem to be using "reference frame" in a different context than everyone else is. Go here, read this:

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

The difference between frames is more than their simply having a different origin.


OOOps, YES, I should not be using the phrase "reference frame". I have avoided this, up until just recently, because I felt it was also ambiguous. I have been saying, coordinate system ( so math ) and saying "reference frame" potentially has physical ramifications.
I should not have used it, it only adds confusion. i will not be using/need the phrase "reference frame", rather Cartesian coordinate system.
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Re: 1067: "Pressures"

Postby ucim » Fri Oct 19, 2012 3:58 pm UTC

steve waterman wrote:Just give me the receipt POINTS and their receipt times.
Velocity of sites at moment of transmission or receipt is TOTALLY irrelevant.
I am talking math, points have no velocity in a Cartesian coordinate system.

Ahhh, but in the universe we live in, velocity of the transmission and reception site does alter the coordinate system, and that is what makes all the difference. It is not a Cartesian system, as it turns out.

steve waterman wrote:Someone talk to me about transmission sequence and stop forcing the conversation to be about any damn receipt sequence.


The transmission sequence is uniquely fixed in four dimensions, which include three of position and one of time. You are attempting to find uniqueness in a one dimensional projection (onto time) of this transmission sequence. This will fail. Simply being in motion (with respect to the emitters) changes the projection, and it is that projection that you (mistakenly) view as an absolute sequence.

Now you have to decide whether or not you want to understand this.

Education is not about being right. It's about becoming right.

You have to decide whether or not you are willing to have been wrong.

If you are, then let us explain it gently using the analogies we have been employing, and instead of resisting, actually follow through on the requests we have made. Pick one poster (so that it is not overwhelming). Re-read their posts, and actually do what they have asked. Take notes at leisure, and report back the results. That poster will follow up, and expect you to do so also. Don't get distracted... follow up with that poster.

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Re: 1067: "Pressures"

Postby CarlLaMagouille » Fri Oct 19, 2012 4:01 pm UTC

To Monika,

I'd say you are right about this, but I think you would need 3 detectors to trinagulate an event in 2+1d, and 4 in 3+1d.

2 detectors cannot make the difference between events on the bissecting plane between them, for instance.

If you know any way to achieve this with only 2 detectors, feel free to explain it to me, so I can tell my GPS to give me my position just with 2 satellites (might reduce the cost of launching the new european GPS, also).

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Re: 1067: "Pressures"

Postby JudeMorrigan » Fri Oct 19, 2012 4:02 pm UTC

steve waterman wrote:
JudeMorrigan wrote:
steve waterman wrote:If we choose a different reference frame ( move where the origin of the reference frame is )

Steve, you seem to be using "reference frame" in a different context than everyone else is. Go here, read this:

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

The difference between frames is more than their simply having a different origin.


OOOps, YES, I should not be using the phrase "reference frame". I have avoided this, up until just recently, because I felt it was also ambiguous. I have been saying, coordinate system ( so math ) and saying "reference frame" potentially has physical ramifications.
I should not have used it, it only adds confusion. i will not be using/need the phrase "reference frame", rather Cartesian coordinate system.

Well, no. You SHOULD be using it. But you should be using it correctly. It's an important concept with very relevant implications that you don't seem to be grasping.

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Re: 1067: "Pressures"

Postby Max™ » Fri Oct 19, 2012 4:06 pm UTC

steve waterman wrote:
Max™ wrote:How do you determine transmission sequence without observing the signals?


Impossible to determine the transmission site or transmission time without receiving the signal.
Observed on not, determined or not, the transmission sequence never-the-less unfolds in a UNIQUE sequence.
Observing the transmission sequence in a different receipt sequence does not alter the historical UNIQUE transmission sequence.
Neither does not observing any receipt sequence.

If it can not be determined in any way, then it does not exist.

Only upon observation can one say what happened, but one observation is just as valid as another, what you are describing is just a mathematical curiosity.
In the same frame as the transmission sequence, there is one observation, in another frame there is another, both are valid.


Two observers can but rely on their singular observation, as they cannot EVER figure out the transmission particulars, even sharing their info together. They can agree upon the transmission site as being some unknown POINT from within the appropriate hyperbola. They both remain in the dark, when it comes to knowledge of the transmission sites or transmission times.

ANY 4 sites are needed to receive the transmitted signal in order to be able to know the transmission site and time.

And any 4 sites in a different frame of reference will also be able to know the transmission site and time, yet they will not necessarily agree with your personally preferred set of observers.
How is this: if several transmitters in different states of motion sent signals, which ordering would be "right"?


At the moment of transmission, the transmission site is a POINT. POINTS are stationary. A receiver going at c/2 receives the signal at ONE POINT. The point is not in motion wrt this particular chosen Cartesian coordinate system.

No, the moment of transmission is an event, it is a location and time.

The receiver traveling at 0.5 c receives the different signals from the different transmissions in a certain order, and orients them in a given frame.

Another receiver with a different state of motion receives the transmissions in another order, and orients them in a different frame.

Just give me the receipt POINTS and their receipt times.
Velocity of sites at moment of transmission or receipt is TOTALLY irrelevant.

You only think this because you've never tried to understand relativity.
I am talking math, points have no velocity in a Cartesian coordinate system.

No you are not, you are trying to act like you are, but if you were talking about the math involved in actual observations you would understand what is wrong with your argument.





OOOps, YES, I should not be using the phrase "reference frame". I have avoided this, up until just recently, because I felt it was also ambiguous. I have been saying, coordinate system ( so math ) and saying "reference frame" potentially has physical ramifications.
I should not have used it, it only adds confusion. i will not be using/need the phrase "reference frame", rather Cartesian coordinate system.

A reference frame IS mathematical.

A cartesian coordinate system is NOT physical.

The universe is not euclidean, you can not apply coordinates defined in an absolute euclidean space onto events in a manifold curved by gravity.
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Re: 1067: "Pressures"

Postby PolakoVoador » Fri Oct 19, 2012 4:10 pm UTC

And here he goes again with the "only mathplease, physics are ugly and stinky and should not be allowed inside our houses".

Circular Steve is circular.

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Re: 1067: "Pressures"

Postby steve waterman » Fri Oct 19, 2012 4:21 pm UTC

Monika

Your thought experiment is right on the issue, well done.

With that in mind Monica, I hope you do not mind too much, that I also get a chance for the brief comments below .

if we have 1 receiver, it only gets to record their PERSONAL receipt sequence

if we have 2 receivers, they get to know the hyperboloid of possible POINTS for the transmission site

If we have 3 receivers, they get to know the transmission time and transmission site
unless the receipt times are all equal, then the possible transmission site is some point on the line,
perpendicular to the plane that the 3 receivers sites mathematically define.

if we have 4 receivers not all in the same plane, they get to know the transmission time and transmission site

added
Schrollini, all I ask is to have random points as input, 3 transmission and 4 receivers.
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Re: 1067: "Pressures"

Postby Radical_Initiator » Fri Oct 19, 2012 4:29 pm UTC

Max™ wrote:
steve waterman wrote:
Max™ wrote:How do you determine transmission sequence without observing the signals?


Impossible to determine the transmission site or transmission time without receiving the signal.
Observed on not, determined or not, the transmission sequence never-the-less unfolds in a UNIQUE sequence.
Observing the transmission sequence in a different receipt sequence does not alter the historical UNIQUE transmission sequence.
Neither does not observing any receipt sequence.

If it can not be determined in any way, then it does not exist.


I might be a little more cautious - I can't prove invisible pink unicorns don't exist, but what I can say is that if they're absolutely unobservable under any conditions whatsoever, they're entirely irrelevant to reality.

Max™ wrote:A reference frame IS mathematical.

A cartesian coordinate system is NOT physical.

The universe is not euclidean, you can not apply coordinates defined in an absolute euclidean space onto events in a manifold curved by gravity.


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Re: 1067: "Pressures"

Postby PolakoVoador » Fri Oct 19, 2012 4:31 pm UTC

Steve, now read Monika's post AGAIN, and remember that people are talking about observers, not detectors. An observer may have 4, 5 or 217 detectors, if you wish.

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Re: 1067: "Pressures"

Postby Schrollini » Fri Oct 19, 2012 4:37 pm UTC

CarlLaMagouille wrote:To Monika,

I'd say you are right about this, but I think you would need 3 detectors to trinagulate an event in 2+1d, and 4 in 3+1d.

2 detectors cannot make the difference between events on the bissecting plane between them, for instance.

If you know any way to achieve this with only 2 detectors, feel free to explain it to me, so I can tell my GPS to give me my position just with 2 satellites (might reduce the cost of launching the new european GPS, also).

It depends what your receptors are capable of measuring. If they are only capable of measuring the time of arrival of a signal, you need n+1 in n+1D. If they are capable of measuring time of arrival and direction of arrival, you only need 2 receptors. If they can measure time of arrival, direction of arrival, and distance to the event, you only need one. (This is how we can use Type 1a supernovas to map out the expansion of the universe.) So if your GPS device had its own atomic clock and direction-sensitive antennas, you could get your position from only two satellites. But you're not going to fit that detector into your cell phone.

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Re: 1067: "Pressures"

Postby eran_rathan » Fri Oct 19, 2012 4:42 pm UTC

steve waterman wrote:
Max™ wrote:How do you determine transmission sequence without observing the signals?


Impossible to determine the transmission site or transmission time without receiving the signal.
[snip]

I am talking math, points have no velocity in a Cartesian coordinate system.


oh, for fuck's sake, not this again.

YOU ARE TALKING ABOUT PHYSICS. PHYSICS!
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Re: 1067: "Pressures"

Postby Max™ » Fri Oct 19, 2012 4:49 pm UTC

To the above: HALLELUJAH!

To this:
steve waterman wrote:Monika

Your thought experiment is right on the issue, well done.

With that in mind Monica, I hope you do not mind too much, that I also get a chance for the brief comments below .

if we have 1 receiver, it only gets to record their PERSONAL receipt sequence

if we have 2 receivers, they get to know the hyperboloid of possible POINTS for the transmission site

If we have 3 receivers, they get to know the transmission time and transmission site
unless the receipt times are all equal, then the possible transmission site is some point on the line,
perpendicular to the plane that the 3 receivers sites mathematically define.

if we have 4 receivers not all in the same plane, they get to know the transmission time and transmission site

added
Schrollini, all I ask is to have random points as input, 3 transmission and 4 receivers.

Computers don't really do random, and to make this relevant for relativity you need two sets of receivers.

Your ABSOLUTE UNIQUE ORDERING is only absolute in the frame you're choosing, that is on you, not the universe, the universe does not specify any frame as uniquely suitable above all others, just you.

I hereby suggest we figure out how to get steve a title: spherical debater, his arguments look the same from any angle.
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Re: 1067: "Pressures"

Postby eran_rathan » Fri Oct 19, 2012 4:50 pm UTC

Max™ wrote:I hereby suggest we figure out how to get steve a title: spherical debater, his arguments look the same from any angle.



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Re: 1067: "Pressures"

Postby Max™ » Fri Oct 19, 2012 4:55 pm UTC

eran_rathan wrote:
Max™ wrote:I hereby suggest we figure out how to get steve a title: spherical debater, his arguments look the same from any angle.



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Re: 1067: "Pressures"

Postby steve waterman » Fri Oct 19, 2012 5:08 pm UTC

Schrollini wrote:
If they can measure time of arrival, direction of arrival, and distance to the event, you only need one.


Each receiver only knows their own (x,y,z) at time of its receipt. This is how my thought experiment functions.

If they can measure time of arrival

Isn't that time always now for the receiver?
How do you propose that one signal receipt allows knowledge of the EXACT transmission time; the distance to the transmission site. I will grant you knowledge of the transmission angle as well, as given.

to all posters -
btw, the word "Detector" is ambiguous as to how many receivers, so, we merely need the word receiver to avoid this ambiguity.
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Re: 1067: "Pressures"

Postby Max™ » Fri Oct 19, 2012 5:12 pm UTC

steve waterman wrote:
Schrollini wrote:
If they can measure time of arrival, direction of arrival, and distance to the event, you only need one.


Each receiver only knows their own (x,y,z) at time of its receipt. This is how my thought experiment functions.

If they can measure time of arrival

Isn't that time always now for the receiver?
How do you propose that one signal receipt allows knowledge of the EXACT transmission time; the distance to the transmission site. I will grant you knowledge of the transmission angle as well, as given.

to all posters -
btw, the word "Detector" is ambiguous as to how many receivers, so, we merely need the word receiver to avoid this ambiguity.

>.>

So your receivers are blind, notified of only a signal arrival from some direction, lack the ability to triangulate observations themselves, and are expected to produce a "unique absolute ordering" somehow?

"Well, I just got the one eye, and I blinked, but I know it was over thattaway somewhere."
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Re: 1067: "Pressures"

Postby speising » Fri Oct 19, 2012 5:12 pm UTC

steve waterman wrote:
btw, the word "Detector" is ambiguous as to how many receivers, so, we merely need the word receiver to avoid this ambiguity.


what about "observer"?

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Re: 1067: "Pressures"

Postby J Thomas » Fri Oct 19, 2012 5:22 pm UTC

Schrollini wrote:
J Thomas wrote:OK. What changes in those fringes would you expect if one beam ran a little slow for awhile and then the speeds were the same at the interferometer? It wouldn't necessarily be the same result you'd get from having one beam travel a longer distance at the same speed, would it?

Interferometry is essentially measuring the lengths of the arms in wavelengths. So you'll get the same result if that measurement changes because the arm length changed or because the wavelength of the light changed. (Note that changing the speed of light changes the wavelength, not the frequency.)


That was going to be my next question! Why is it necessary that the wavelength change rather than the frequency?

Interferometry is generally worried about how the arm length (as measured in wavelengths) changes, not what the absolute length is. A changing arm length shows up as motion of the fringes. When the difference in the arm lengths has changed by one wavelength of light, you'll have seen the fringes move by one fringe spacing. When I did interferometry with a laser (monochromatic and long coherence length), I did nothing special to make sure my arms were the same length. As long as the difference in lengths was less than the coherence length of the laser (a few cm, if I remember), I was fine. Michelson and Morley were using white light (polychromatic and short coherence length), so they did need to get the arm lengths the same. But, still, they were only measuring the change in the arm lengths: They floated there setup on a mercury bath, set it to spin slowly, and then saw how the fringes moved during the rotation. They saw that the fringes barely moved at all, meaning the arm lengths (as measured in wavelengths!) were barely changing. Since they knew the actual arm lengths weren't chaning, they interpretted this as a restriction on how much the wavelength of light was changing, and therefore a restriction on how much the speed of light was changing. Wikipedia has more details, including plots of Michelson and Morley's observed shifts.


OK, I have all that. You don't need the lengths to be the same when you're interested in changes in length, because you can tell it's changing when the interference fringe changes.

I've looked at the simple math that intro physics students get, and they make it look like being one whole wavelength off should give about the same result as no wavelengths off. I get the feeling it's more complicated than that....

And the fringes come because you don't get your two light beams parallel, and the "wave front" (I'm not sure I'm using that word right) isn't flat. Is there any other reason for the fringes? If you simulate that with only those parameters changing, will you get the fringe pattern you actually see?
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Re: 1067: "Pressures"

Postby steve waterman » Fri Oct 19, 2012 5:34 pm UTC

Max™ wrote:So your receivers are blind, notified of only a signal arrival from some direction,


Yes, however, direction too is not required to manifest the transmission site and time.
ONLY the quantity of receivers is critical.

lack the ability to triangulate observations themselves,


Yes, since they only have the one receipt, also kinda impossible.

and are expected to produce a "unique absolute ordering" somehow?


They cannot! Nor could two receivers collectively either.

You are missing the part that we require 4 receivers to do the math to extrapolate THE transmission site and time.

"Well, I just got the one eye, and I blinked, but I know it was over thattaway somewhere."


Exactly, one observer/receiver logic can only be applied.

Again, we do not require angle knowledge ever to do this "transmission math".

We require 4 random receiver points and three random transmission points.
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Re: 1067: "Pressures"

Postby jpers36 » Fri Oct 19, 2012 5:42 pm UTC

I have Steve foed, so I usually only see his posts when they are selectively quoted and responded to by others in the forum. I think it filters out the worst of his irrationality. But every so often I succumb to the temptation to expand one of his posts. The direct exposure makes me laugh, but it also makes my head hurt.

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Re: 1067: "Pressures"

Postby PolakoVoador » Fri Oct 19, 2012 5:43 pm UTC

Spherical debater. I like the sound of this :D

And Steve:
Fine, 4 receivers needed. Now consider this definition:
1 OBSERVER = 4 RECEIVERS, not all at the same plane.

That means every observer can measure some order of events. BUT, different observers at different reference frames will measure different orders of events.

Get it now?

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Re: 1067: "Pressures"

Postby Monika » Fri Oct 19, 2012 5:47 pm UTC

CarlLaMagouille wrote:To Monika,

I'd say you are right about this, but I think you would need 3 detectors to trinagulate an event in 2+1d, and 4 in 3+1d.

I am thinking of detectors that can see the source of light emission (and of course record a time when they receive it). So 2 detectors are enough. Each of them can find out a line on which the event lies. Intersecting two lines results in a point.

2 detectors cannot make the difference between events on the bissecting plane between them, for instance.

Okay, so you're using detectors that can only record when the signal arrived, but they don't see the source, right?

I am not sure which type is used by GPS. I guess it could be the type of detector you are thinking of, so 4 detectors would indeed be needed.

steve waterman wrote:Monika

Your thought experiment is right on the issue, well done.

Great. So you understand now that when we say "observer 1 observed order event 1 and event 2 to be simultaneous" we do in fact NOT mean "observer 1 received the signals from event 1 and event 2 at the same time", right? So you will stop saying "reception time is irrelevant here!", right?

With that in mind Monica, I hope you do not mind too much, that I also get a chance for the brief comments below .

if we have 1 receiver, it only gets to record their PERSONAL receipt sequence

Not sure if you mean 1 observer (1 reference frame) or you mean 1 detector (of which there could be several in a reference frame) and which style of detector you mean, but if you mean 1 detector and you mean a style-II detector that can record both the light source (direction) and the time then I agree, it cannot figure out the sending sequence.

if we have 2 receivers, they get to know the hyperboloid of possible POINTS for the transmission site

Not sure how you mean that, can you make a picture of that?

If we have 3 receivers, they get to know the transmission time and transmission site
unless the receipt times are all equal, then the possible transmission site is some point on the line,
perpendicular to the plane that the 3 receivers sites mathematically define.

You realize there are infinitely many such lines? Actually any point is on some line that is perpendicular to that triangle.

if we have 4 receivers not all in the same plane, they get to know the transmission time and transmission site

What do your "receivers" (which seem to be detectors, not observers / reference frames) record?
Do they see the light source, i.e. from which direction the light is coming? (Style II) Or do they only record the time when the light is received? (Style I)
Obviously they are not working like police speed guns that also measure the distance.
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Re: 1067: "Pressures"

Postby Schrollini » Fri Oct 19, 2012 5:50 pm UTC

J Thomas wrote:
Schrollini wrote:
J Thomas wrote:OK. What changes in those fringes would you expect if one beam ran a little slow for awhile and then the speeds were the same at the interferometer? It wouldn't necessarily be the same result you'd get from having one beam travel a longer distance at the same speed, would it?

Interferometry is essentially measuring the lengths of the arms in wavelengths. So you'll get the same result if that measurement changes because the arm length changed or because the wavelength of the light changed. (Note that changing the speed of light changes the wavelength, not the frequency.)


That was going to be my next question! Why is it necessary that the wavelength change rather than the frequency?

Think for instance of light entering a block of glass and slowing down. Just on the outside, the electric field is oscillating at some frequency. This is causing the electric field just inside the glass to also oscillate at that same frequency. In other words, if the frequency changed, the eletric field inside and outside would get completely out of phase, leading to all sorts of strange discontinuities at the surface. We don't want that. So the frequency must stay the same, which leaves only the wavelength to vary.

In the case of the Michelson-Morley interferometer, you have the same argument where the light changes direction, before and after it bounces of a beam splitter, for example.

J Thomas wrote:
Interferometry is generally worried about how the arm length (as measured in wavelengths) changes, not what the absolute length is. A changing arm length shows up as motion of the fringes. When the difference in the arm lengths has changed by one wavelength of light, you'll have seen the fringes move by one fringe spacing. When I did interferometry with a laser (monochromatic and long coherence length), I did nothing special to make sure my arms were the same length. As long as the difference in lengths was less than the coherence length of the laser (a few cm, if I remember), I was fine. Michelson and Morley were using white light (polychromatic and short coherence length), so they did need to get the arm lengths the same. But, still, they were only measuring the change in the arm lengths: They floated there setup on a mercury bath, set it to spin slowly, and then saw how the fringes moved during the rotation. They saw that the fringes barely moved at all, meaning the arm lengths (as measured in wavelengths!) were barely changing. Since they knew the actual arm lengths weren't chaning, they interpretted this as a restriction on how much the wavelength of light was changing, and therefore a restriction on how much the speed of light was changing. Wikipedia has more details, including plots of Michelson and Morley's observed shifts.


OK, I have all that. You don't need the lengths to be the same when you're interested in changes in length, because you can tell it's changing when the interference fringe changes.

I've looked at the simple math that intro physics students get, and they make it look like being one whole wavelength off should give about the same result as no wavelengths off. I get the feeling it's more complicated than that....

Nope. With a coherent monochromatic light source, you can't tell the integer part of the number of wavelengths the arms differ by. This is why Michelson and Morley didn't take a measurement, spin the detector 90o, and take another. Instead, they slowly rotated it so they could watch the fringes move as the arm lengths changed by fractions of a wavelength.

J Thomas wrote:And the fringes come because you don't get your two light beams parallel, and the "wave front" (I'm not sure I'm using that word right) isn't flat. Is there any other reason for the fringes? If you simulate that with only those parameters changing, will you get the fringe pattern you actually see?

Those are the two reasons I could think of off the top of my head. I suspect the former is the major factor in typical experiments, but that's just a guess. And there's no magic going on; all you're doing is measuring the intensity of the EM field. If you measure the fringe spacing and compare it to the wavelength of light, you can work out how non-parallel the beams are. I got visible light fringes with a spacing on the order of millimeters, so we must be talking under a thousandth of a radian or a tenth of a degree.
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Re: 1067: "Pressures"

Postby steve waterman » Fri Oct 19, 2012 6:17 pm UTC

PolakoVoador wrote:Spherical debater. I like the sound of this :D

And Steve:
Fine, 4 receivers needed. Now consider this definition:
1 OBSERVER = 4 RECEIVERS, not all at the same plane.

That means every observer can measure some order of events. BUT, different observers at different reference frames will measure different orders of events.

Get it now?


An observer and a receiver mean the same exact thing.

1 OBSERVER = 1 OBSERVER
4 RECEIVERS = 4 RECEIVERS
2 detectors = 2 detectors
3 sensors - 3 sensors
5 incoming signal recorders = 5 incoming signal recorders.

1 observer does not EQUAL 4 receivers. Give me a break. Indeed, I should wrap those up for today, and give my eyes some needed time away from the white screen. I may try to read stuff posted later tonight, possibly even post, depending upon my vision at the time. Glasses only make the whole thing 10 times worse for me.

I try to reflect upon your posts at night, get up and read myself up to date, and respond as much as I can, until it starts to show signs of visual difficulties. I wish this were not so, but I am not so foolish as to not respect this condition of mine. This method has been working to keep down little runs of the migraines that I do so wish to avoid.

My focus remains, to attempt to determine THE transmission sequence with a 3d+time applet, only given 3 random transmissions and 4 random receivers.

Words are nice, but subjective often, but the MATH for the applet is what really counts.
The applet WILL manifest the same transmission sequence regardless of random input for transmissions and receivers.
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Re: 1067: "Pressures"

Postby Max™ » Fri Oct 19, 2012 6:19 pm UTC

steve waterman wrote:
Max™ wrote:So your receivers are blind, notified of only a signal arrival from some direction,


Yes, however, direction too is not required to manifest the transmission site and time.
ONLY the quantity of receivers is critical.

So now you're wanting multiple receivers to receiver signals with only the time known, and multiple signals, and somehow determine absolutely which order these events happen in?

lack the ability to triangulate observations themselves,


Yes, since they only have the one receipt, also kinda impossible.

and are expected to produce a "unique absolute ordering" somehow?


They cannot! Nor could two receivers collectively either.

You are missing the part that we require 4 receivers to do the math to extrapolate THE transmission site and time.

No sweetheart, I'm not missing anything here, I know you think we're ignoring your critical breakthrough, but I assure you I am not.

I am just trying to point out that the problem here isn't what you think you know, it's what you think you know that just isn't so.

"Well, I just got the one eye, and I blinked, but I know it was over thattaway somewhere."


Exactly, one observer/receiver logic can only be applied.

Again, we do not require angle knowledge ever to do this "transmission math".

We require 4 random receiver points and three random transmission points.

Baffling.
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Re: 1067: "Pressures"

Postby CarlLaMagouille » Fri Oct 19, 2012 6:38 pm UTC

Schrollini wrote:It depends what your receptors are capable of measuring. If they are only capable of measuring the time of arrival of a signal, you need n+1 in n+1D. If they are capable of measuring time of arrival and direction of arrival, you only need 2 receptors. If they can measure time of arrival, direction of arrival, and distance to the event, you only need one. (This is how we can use Type 1a supernovas to map out the expansion of the universe.) So if your GPS device had its own atomic clock and direction-sensitive antennas, you could get your position from only two satellites. But you're not going to fit that detector into your cell phone.


Thanks, that makes sense. I was assuming we were dealing with simple light-emitting events and sensors that can only detect the passage of a light pulse.

Obviously, the GPS problem is really not the same thing, and I never thought of actually using direction-sensitive antennas. As anyone tried this one? I mean, you would need some damn precise antenna to get your location this way. I figure there is no need for this as long as you can get an average of more than 10 satellites almost everywhere in the world.

I don't know why, but this makes me thinks about pirates. Yeah!

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Re: 1067: "Pressures"

Postby JudeMorrigan » Fri Oct 19, 2012 7:01 pm UTC

steve waterman wrote:1 observer does not EQUAL 4 receivers. Give me a break.

Umm, Steve. People have been really clear that they've been referring to multi-sensor observers. See this post for example:

Schrollini wrote:Each three-sensor observer picks out a single event in space time

viewtopic.php?f=7&t=85881&start=3360#p3156675

Really, Steve, you have to read what people are writing.

Words are nice, but subjective often, but the MATH for the applet is what really counts.

Then why are you ignoring it in favor of science by democracy and insisting (with words, not math!) that adding redundant observers/detectors/whateverthehellyouwanttocallthemtoday will magically make relativity go away?

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Re: 1067: "Pressures"

Postby ivnja » Fri Oct 19, 2012 7:14 pm UTC

Suddenly, humans - who come standard with two built-in visual detectors (or are they sensors, receivers, or incoming signal recorders?) - no longer count as observers.
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Re: 1067: "Pressures"

Postby J Thomas » Fri Oct 19, 2012 7:37 pm UTC

Schrollini wrote:
J Thomas wrote:
Schrollini wrote:Interferometry is essentially measuring the lengths of the arms in wavelengths. So you'll get the same result if that measurement changes because the arm length changed or because the wavelength of the light changed. (Note that changing the speed of light changes the wavelength, not the frequency.)


That was going to be my next question! Why is it necessary that the wavelength change rather than the frequency?

Think for instance of light entering a block of glass and slowing down. Just on the outside, the electric field is oscillating at some frequency. This is causing the electric field just inside the glass to also oscillate at that same frequency. In other words, if the frequency changed, the eletric field inside and outside would get completely out of phase, leading to all sorts of strange discontinuities at the surface. We don't want that. So the frequency must stay the same, which leaves only the wavelength to vary.


Thank you! That's very clear and sensible.

Still I wonder if there could be some other way. Like, when the light is changing speed because of a velocity change that isn't from the density of the medium, could it possibly start out at the original velocity and gradually change frequency? Like, over several wavelengths? Then if the velocity and frequency changed together everything could be right at the surface it just left. Or if the velocity changes instantly but the frequency and wavelength change together later then also the surface could be fine.

It seems silly to suggest this, but no more silly than relativity.
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Re: 1067: "Pressures"

Postby eran_rathan » Fri Oct 19, 2012 7:39 pm UTC

CarlLaMagouille wrote:
Schrollini wrote:It depends what your receptors are capable of measuring. If they are only capable of measuring the time of arrival of a signal, you need n+1 in n+1D. If they are capable of measuring time of arrival and direction of arrival, you only need 2 receptors. If they can measure time of arrival, direction of arrival, and distance to the event, you only need one. (This is how we can use Type 1a supernovas to map out the expansion of the universe.) So if your GPS device had its own atomic clock and direction-sensitive antennas, you could get your position from only two satellites. But you're not going to fit that detector into your cell phone.


Thanks, that makes sense. I was assuming we were dealing with simple light-emitting events and sensors that can only detect the passage of a light pulse.

Obviously, the GPS problem is really not the same thing, and I never thought of actually using direction-sensitive antennas. As anyone tried this one? I mean, you would need some damn precise antenna to get your location this way. I figure there is no need for this as long as you can get an average of more than 10 satellites almost everywhere in the world.

I don't know why, but this makes me thinks about pirates. Yeah!


Actually, airports use this system (of precise directional antennas). The VOR system is one example of this (well, the signal has a precise directionality, the antennas do not).
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Re: 1067: "Pressures"

Postby brenok » Fri Oct 19, 2012 8:22 pm UTC

Is anybody planning the commemorations of the 100th page of the thread? (Is this the longest in the subforum?)

(edit) Wow, the runner-up is not even close, only 51 pages...

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Re: 1067: "Pressures"

Postby ucim » Fri Oct 19, 2012 8:35 pm UTC

brenok wrote:Is anybody planning the commemorations of the 100th page of the thread? (Is this the longest in the subforum?)

(edit) Wow, the runner-up is not even close, only 51 pages...

My detector says there are only twelve pages, but they all happened three months from now. :)

btw, this thread has more pages than "Religion - the deuce" (Serious Business)! I wonder if there are any similarities in the subject matter.

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Re: 1067: "Pressures"

Postby Radical_Initiator » Fri Oct 19, 2012 8:35 pm UTC

brenok wrote:Is anybody planning the commemorations of the 100th page of the thread?

I'm planning on sacrificing a goat on a Waterman polyhedron altar in the name of Descartes in the hopes that it goes on forever.
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Re: 1067: "Pressures"

Postby Schrollini » Fri Oct 19, 2012 8:51 pm UTC

J Thomas wrote:Still I wonder if there could be some other way. Like, when the light is changing speed because of a velocity change that isn't from the density of the medium, could it possibly start out at the original velocity and gradually change frequency? Like, over several wavelengths? Then if the velocity and frequency changed together everything could be right at the surface it just left. Or if the velocity changes instantly but the frequency and wavelength change together later then also the surface could be fine.

I don't think you can get around this with a continuous transition. Suppose you had some zone where the frequency slowly changed by 1 Hz, say. Count the peaks as they enter this zone and as they leave it. After 1 second, one more peak will have entered than left. After 10 seconds, there will be 10 missing peaks. You can't make the peaks disappear, at least with linear materials, so this can't work.

However, there are various nonlinear optical materials that do funny things to the frequency of light as it travels through them. I don't know of any that produce a continuous change in frequency; generally the effects are frequency multiplication and, if you have multiple frequencies present, heterodyning. But the world is a wild place, so I won't say it can't happen.

You might wonder why, if relativity says space and time are the same (sorta), only the wavelength changes, and not the frequency. Well ... I'm not entirely sure. I think it's because we have an index of refraction that's varying in space but not in time. If we had a medium with a constant index of refraction that suddenly changed at some instant in time, I think we would see the wavelength stay constant (because the peaks can't move instantly) and the frequency subsequently shift (to maintain the correct relation for the velocity). Does that sound right to others?

Radical_Initiator wrote:I'm planning on sacrificing a goat on a Waterman polyhedron altar in the name of Descartes in the hopes that it goes on forever.

Make sure you ritually scream until you lose your voice first. After all, you can't put Descartes before the hoarse.
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Re: 1067: "Pressures"

Postby Monika » Fri Oct 19, 2012 9:17 pm UTC

steve waterman wrote:
PolakoVoador wrote:Spherical debater. I like the sound of this :D

And Steve:
Fine, 4 receivers needed. Now consider this definition:
1 OBSERVER = 4 RECEIVERS, not all at the same plane.

That means every observer can measure some order of events. BUT, different observers at different reference frames will measure different orders of events.

Get it now?


An observer and a receiver mean the same exact thing.

No, they dont.

1 OBSERVER = 1 OBSERVER
4 RECEIVERS = 4 RECEIVERS
2 detectors = 2 detectors
3 sensors - 3 sensors
5 incoming signal recorders = 5 incoming signal recorders.

And 17 cats = 17 cats. Writing n things = n things means absolutely nothing, everything is equal to itself.
Maybe you meant to write: observer = receiver = detector = sensor = incoming signal recorder. This is wrong.

An observer is something that can measure the time and location of an event (measure something and from that calculate the time and location of that event) (in its own spacetime coordinate system). You cannot redefine this, this is what the word means when discussing Relativity. You do not get a say in this.

I avoided receiver because it was unclear if receiver is meant to be a synonym for for observer or for the individual detection devices / sensor.

1 observer = 1 sensor/incoming signal recorder if it can determine the time of arrival, the direction and the distance (Style 3)
1 observer = 2 sensors/incoming signal recorders if they can determine the time or arrival and the direction (Style 2)
1 observer = 4 sensors/incoming signal recorders if they can determine only the time of arrival

So, your receiving thingies, what can they do, record the time of arrival and the direction where the light came from, or just the time of arrival?

1 observer does not EQUAL 4 receivers. Give me a break.

Give us a break. You're wrong.

Words are nice, but subjective often, but the MATH for the applet is what really counts.

Your words are wrong and your math is wrong, too.

CarlLaMagouille wrote:I don't know why, but this makes me thinks about pirates. Yeah!

Huh, how did this make you think of pirates?


edit: I deleted "detectors" in the sense of sensors because the applets use "detectors" in the sense of "observers". I will avoid both "detectors" and "receivers" and instead only use "observers" and "sensors".
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Re: 1067: "Pressures"

Postby CarlLaMagouille » Fri Oct 19, 2012 9:39 pm UTC

Monika wrote:Huh, how did this make you think of pirates?


Everything is related to piracy. And relativity and piracy makes a cool mix.

I think I'll just watch Cowboy Bebop again.


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