[geistkiesel]

The original Sagnac Effect has photons traveling in opposite directions around a circular path The circle is turning and therefore the photons do not arrive at the physical emission point simultaneously. Einstein suggsted that the Sagnac Effect be "unwrapped" into a linear form (avoiding the noninertial aspects of circlar motion, re AE), which is presented here. The circumferences are 'unwarapped' and described in linear form. The Sagnac Effect is invariant in this form as were all the other variations through the history of the effect.

Some may recognize the experimental arrangement below in the schematic that is published in various forms as an educational deganken.As an aside, one of the references makes the point that Einstyein never mentioned the Sagnac effect even though it preceded his seminal SR paper.

Photons emitted from the midpoint of L and R [the "R" inadvertently remioved from schematic] clock/reflectors attached to an inertial frame moving in the L to R direction. The L detector detects the lp, left photon, before the rp, right photon, is detected by R (SRT insists this is not possible). When reflected from L and R the photons arrive simultaneously at the physical midpoint in a time t' ,which is that extra time greater than the round trip of photons moving in a stationary inertial frame.

A t' > 0 proves motion, a t' = 0 proves the frame is at rest.

All clock values are measured in the moving inertial frame from which the absolute velocity is calculated. Distances and timing functions are derived from unambiguous locations of the photon wave train, by inspection.




References:
Virtually all the papers discuss special relativity, but this is not necessarily the primary focus of the papers.


Describes the original Sagnac Effect

Best written paper overall with excellect references

Sagnac Laser Interferometer precursor?

Reinterprets Michelson-Morely Experiment re Sagnac.

Consise and informative focus on SRT.

Brief but tells the story.

Modied Lorentz Ether Theory (MLET)

Need access to Physical review.

If you prefer, simply google , "sagnac effect".

Geistkiesel :cool:

[swansont]

Or, one could use a Michelson interferometer and look for interference as evidence of absolute motion. Wait a moment...that's already been done!

As one of you links notes, GPS and geostationary satellites that have to account for earth rotation via the Sagnac effect do not have to account for the linear effect due to the earth's motion, to which they would be very sensitive.

[geistkiesel]

Quote

Or, one could use a Michelson interferometer and look for interference as evidence of absolute motion. Wait a moment...that's already been done!

As one of you links notes, GPS and geostationary satellites that have to account for earth rotation via the Sagnac effect do not have to account for the linear effect due to the earth's motion, to which they would be very sensitive.

Swansont,

You are aware that MM and D. Miller both found an 8.8 km/sec motion wrt the ether aren't yoyu? You are aware that MM applied a grossly flawed postulate of light motion in creating their mathematiocalsteructure for the various timing scenarios? You are aware that light emitted orthogonally to a frame of reference does not inheirit any of the frame velocity or momentum conponenets do you not?

What is linear reagrdinbg the earth motion? You aren't suggesting that SRT calls some curved motion inertial and another accelerating are you?

I saw a brief discussion between yourself and another where you proclaimed yourself a PhD, in Physics I presume. The response you have posted here, is this all you have? Of all the SR remarks you have posted, and believe me, I recognize you as a true expert in SRT, you mean to say that the MM and GPS reference in their spartan form is the extent of your comments?

Not a single "for crying out loud?"

You must have recognized that the emission point of simultaneously emitted photons is a localized point is space that is invariant, even a single photon emission defines an absolute point in space. The observer can add nothing to the information available to him that can rescue the obvious implications. He may consider himself at rest wrt the embankment, or the emission point, I call it the zero-point, origin of the coordinate system, yet he is lost in invoking the "at rest with respect to the embankment" that is truly quietly at rest.

I do not mean to embarrass you Swansont, but your reply is certainly below the minimum standard of expertise that we at Science Forums expect of a man of your talents, education anmd experience. You recognize that all the historically fallen physical theories before now did not drive all adherents to the theory to a life of crime, nor will you be forcesd to respond to the ""we are hiring" signs found on most MacDonald's Fast Food concerns.

Look at it this way, if I am correct, me and the rest of the "SRT dissidents" gain nothing, you lose nothing. If it were me, no matter what age or personal situation I was in, I would not want to carry around an albatrioss as massive as SRT should it be provesd false. Which it has been proved. I would think that anyone calling himself, or herself , a scientist would want to know what the real, or more true strory happened to be. But then that is me, and I am learning very clearly that the rest of he world has a few objectionists to the waY I see things, how rude they are, don't you agree?.

I am speculating here, but I trhink that you have never bneen fully apprised of the classical world of physics. None of us living now have been either. It is a brand new ball game, but the rules have changed somewhat, which is the nature of the ball game we fine ourselves playing currently. My guess is thagt Tom Mattson will not respond either, this may be above even Tom, another classical physicist virgin.

Oh well, maybe someone will have a question or two about the dawning reality of their world. I would really like to be able to claim that this was my sole invention, a unique discovery, but in many ways it has already been said by many that preceeded me and contemporaries alike, unfortunately for my flattened ego, I just ain't the glorious type, perhaps it is the deep sense of personal humility I manifest that drives supporters away. However, the physics will stand much longer than myself, or so I have been informed.

Take a look at it Swansont, maybe there is a glich, a slight crack in the dike? perhaps?

Geistkiesel :cool:

[timo]

Bother to sum up what this thread is about? I can´t really see your point and I don´t really want to spend too much time thinking about what you meant by terms like "invariant emission point" or statements like "SRT insists this [one photons hits the edge before the other one] is not possible".

[Johnny5]

I am just reading about the Sagnac effect now, it will be interesting to see how long it takes me to understand it.

Apparently, in 1913 French scientist 1869-Georges Sagnac-1926 came up with a way to modify the Michelson Morely experiment.

Here is one source which describes the "Sagnac effect", and the relevent quote: Article on Sagnac effect

Quote

Several types of modern gyroscopes function by using the Sagnac effect to measure rotation. Georges Sagnac performed the original experiment in 1913. He split a light beam into two parts, which traveled around the circumference of an area in opposite directions. He then measured the interference fringe effect when the two light beams were brought back together. He found that the fringe shift was a function of the rotational velocity. In other words, the speed of light relative to the rotating sensor was a function of whether the light beam traveled with or against the rotational velocity of the platform. The MLET explanation of the Sagnac effect is again obvious. Simply stated, the motion of the detector (observer) has no effect on the speed of light; and therefore a non-isotropic light speed relative to the moving detector can be expected—which leads to the observed phenomenon.

Here is an article from the encylopedia Brittanica: Article2 on Sagnac Effect

Ok, so the "Sagnac Effect" is one method of measuring rotation. That I consider useful and important.

Today, optical gyroscopes (based on the Sagnac Effect) are replacing mechanical gyroscopes, because the optical gyroscopes have no moving parts.

Geistkeisel said:

The original Sagnac Effect has photons traveling in opposite directions around a circular path The circle is turning and therefore the photons do not arrive at the physical emission point simultaneously.

So the "circle is turning."

The device is spinning, with some angular velocity.


"Photon's do not arrive at emission point simultaneously"

Well of course not, because the circle is turning.

Let me find a picture of it.

Here is a picture: Article 3 on Sagnac effect


This is interesting:

Quote

Sagnac rotated his turntable at two revolutions per second and found the expected effect; that is, he demonstrated that absolute rotation could be measured. Unfortunately, Sagnac's experiment has never been performed accurately enough to discern whether the period of absolute rotation is the solar day of 24 hours or the sidereal day of 23 hours, 56 minutes. Source

Everyone's thoughts on this appear somewhat scattered.

Somewhere in the universe is the center of mass of the universe.


Set up a rectangular coordinate system, with that point permanently fixed at the origin.

Now, there are stars everywhere, in that frame. If the frame is spinning wildly out of control, then to an observer whose location is fixed in the frame, it will appear as if the stars are spinning out of control.

And this will show up in his calculation of the total kinetic energy of the universe.

But in just the right frames, the centers of mass of various galaxies obey Galileo/Newtons Law of Inertia.

All such frames will be inertial reference frames.

Now, the quote above, says that Sagnac rotated his turntable at two revolutions per second.

Then it says that he "found the expected effect."

Then the caption makes reference to "absolute rotation."

Here is something interesting about Physicist H.E. Ives: Article making reference to Ives

Quote

Phipps has just published this paper in the American Journal of Physics, v. 54, pp. 245-247 (1986), showing how Mercury's perihelion advance can be explained according to special relativity. He uses planetary mass variation of the planet, as did the famous American physicist H.E. Ives, to achieve this result. [H.E. Ives, Jour. Optical Soc. Am., v. 38, p. 413 (1948)].

Cross with this source:

Quote

The reverse is true if the turntable rotates in the opposite sense. Sagnac rotated his turntable at two revolutions per second and found the expected effect; that is, he demonstrated that absolute rotation could be measured. Unfortunately, Sagnac's experiment has never been performed accurately enough to discern whether the period of absolute rotation is the solar day of 24 hours or the sidereal day of 23 hours, 56 minutes.

It was subsequently pointed out by Ives (3) that the theory of relativity cannot explain Sagnac's result. This means that the very theory needed to explain why the earth "looks" stationary in Michelson-Morley type experiments predicts that similarly, the earth should not appear to rotate! Thus experiments indicate that the earth is not moving through the aether but that there is rotation.

3) Ives, H.E., 1938. Jrnl. of the Optical Soc. of Am., 28:296
Sagnac effect

Right now, I am reading the source which you said was excellent:

Article

Ok I am focusing on the mathematics, which is accompanied by figure 2.

The Circular Sagnac Effect

They use the symbol t₀ for the time taken for a photon to travel around the circular path, when the motor which causes the device to rotate is off.

I have a good book (Numerical Methods For Scientists And Engineers-1962) on the finite discrete difference calculus, written by R.W. Hamming, and the difference calculus would use Delta t, for an amount of time. So I am just going to switch that to:

Dt₀

So this denotes an amount of time, which is measured by a clock at rest in a frame attached to the surface of the earth, and the measurement is made when the device isn't spinning in the frame.

For whatever it is worth, the Hamming code is named after him.

Richard Hamming

His book is really good, and influenced me mathematically so to speak.

So now, let there be a coordinate system at rest in this frame, with its origin at the center of the circle, and the circle lying in the XY plane of the frame.

Now, the photon will have some speed in the frame. Denote that speed by v. I deliberately did not choose c to denote the speed.

So v is the speed of a photon, as defined in this frame of reference and no other.

Now, let us presume that the tangential speed of the photon is uniform in this frame. The tangential speed of the photon is constant, but the velocity of the photon in this frame is changing. The photon is travelling in a circle, with radius R.

So the photon has a nonzero centripetal acceleration, related to v, and to R as follows:

a_c = v²/R

Distance around the circle = 2 pR

And speed = distance traveled/travel, hence:

v = 2 pR/Dt₀

Assuming that the speed of the photon isn't zero in this frame, we can divide both sides by v to obtain:

Dt₀ = 2 pR/v

The article then makes reference to the time measured aboard the spinning disc t`.

I need to think about this carefully.

From the diagram, the photon which moves against the rotation, reaches the detector before the photon which moves with the rotation, assuming that the two photons began their circular journey simultaneously, and have the same speed in the earth frame.

Let the constant angular speed of the device in the earth frame be represented by w.

Let the tangential speed of the device in the earth frame be denoted by v_t.

The tangential speed of a point fixed on the rotating disc is related to the angular speed in the earth frame, and the radius of the disc as follows:

v_t = wR

Let t1=0 denote the moment in time, at which the two photons begin their circular journey.

Later, the device will have rotated through some angle =q, at which moment in time, the photon moving against the direction of rotation will be back at the starting point(the detector).

Call this moment in time t2.

So this is an event, marked by two moments in time t1,t2.

I will represent this event by the notation [t1,t2].

Now, during the event [t1,t2], the total distance which the photon traveled in the earth frame, is less than 2 pi r.

Focus on the circle in figure 2(labeled "Whole apparatus turning at w clockwise").

There are two sectors to focus on. One bounded by circular arc SS`, and a larger sector bounded by circular arc SS``.

Call the photon moving counterclockwise photon A, and call the photon moving clockwise photon B.

So the total distance traveled by photon A, during event [t1,t2] is given by:

2p R - Rq.

Where theta is the angle subtended by arc SS`.

Now, let the amount of time which this took, as measured by a clock at rest in the earth frame be denoted by:

Dt1

And a small amount of time later, photon A will have traveled a full circle, in the earth frame.

Let us denote this amount of time by:

Dt2

Lets add the two times together to obtain:

Dt1 + Dt2

And this is the amount of time, that we previously denoted by:

Dt₀

Therefore:

Dt₀ = Dt1 + Dt2

And we already defined the speed of photon A in this frame as:

v = 2 pR/Dt₀

Now, denote the moment in time at which Photon A has traveled a distance of 2 pi R in the earth frame, as t3.

So t1 before t2 and t2 before t3.

Now, if the two photons have the same speed in the earth frame, then at moment in time t3, photon B will also have traveled a distance of 2 pi R in the earth frame, and so the two photons will be right back next to each other simultaneously. But at moment in time t3, the disc advanced slightly, because it is spinning in the earth frame, and so there will be a still later moment in time t4, at which moment photon B will finally coincide with the detector (which is fixed to the spinning disc).


So the whole phenomenon can be broken into parts.

[t1,t2] union [t2,t3] union [t3,t4]

t1 corresponds to the moment in time at which the photons are simultaneously emitted.

t2 corresponds to the moment in time at which photon A passes the detector.

t3 corresponds to the moment in time at which photon A and photon B pass each other.

t4 corresponds to the moment in time at which photon B passes the detector.

[swansont]

Quote

Swansont,

You are aware that MM and D. Miller both found an 8.8 km/sec motion wrt the ether aren't yoyu? You are aware that MM applied a grossly flawed postulate of light motion in creating their mathematiocalsteructure for the various timing scenarios? You are aware that light emitted orthogonally to a frame of reference does not inheirit any of the frame velocity or momentum conponenets do you not?

What is linear reagrdinbg the earth motion? You aren't suggesting that SRT calls some curved motion inertial and another accelerating are you?

If you have actual scientific objections, by all means post some citations. It has been my experience that the nebulous objections posted are often taken out of context, and context is important. So is defining unusual terms and words, like "mathematiocalsteructure"

The deviation of the earth from being an inertial frame is quantifiable, as I have discussed elsewhere. Approximating it as one can be done, as long as the effects of rotation can be shown to be small. It's a matter of degree.

Quote

I saw a brief discussion between yourself and another where you proclaimed yourself a PhD, in Physics I presume. The response you have posted here, is this all you have? Of all the SR remarks you have posted, and believe me, I recognize you as a true expert in SRT, you mean to say that the MM and GPS reference in their spartan form is the extent of your comments?

Not a single "for crying out loud?"

...

I do not mean to embarrass you Swansont, but your reply is certainly below the minimum standard of expertise that we at Science Forums expect of a man of your talents, education anmd experience. You recognize that all the historically fallen physical theories before now did not drive all adherents to the theory to a life of crime, nor will you be forcesd to respond to the ""we are hiring" signs found on most MacDonald's Fast Food concerns.

...

I am speculating here, but I trhink that you have never bneen fully apprised of the classical world of physics. None of us living now have been either. It is a brand new ball game, but the rules have changed somewhat, which is the nature of the ball game we fine ourselves playing currently. My guess is thagt Tom Mattson will not respond either, this may be above even Tom, another classical physicist virgin.

Oh well, maybe someone will have a question or two about the dawning reality of their world. I would really like to be able to claim that this was my sole invention, a unique discovery, but in many ways it has already been said by many that preceeded me and contemporaries alike, unfortunately for my flattened ego, I just ain't the glorious type, perhaps it is the deep sense of personal humility I manifest that drives supporters away. However, the physics will stand much longer than myself, or so I have been informed.

The extent of my comments is in part a function of how much time I have to spend online. If I or anybody else does not respond to you, it may be related to how rude and condescending you are being, and how willing you appear to be to engage in honest discussion. I have no desire to waste my time in threads that are of no value to me. As for the "minimum standard of expertise that we at Science Forums expect" I rather doubt you speak for anyone else here, and I am sorely tempted to tell you where you can stick your expectations.

[geistkiesel]

Atheist]Bother to sum up what this thread is about? I can´t really see your point and I don´t really want to spend too much time thinking about what you meant by terms like"invariant emission point" or statements like "SRT insists this [one photons hits the edge before the other one said:

is not possible".

Atheist,
This goes to the heart of special relativity theory, a religion practiced by many.. When the photons are emitted at the midpoint of the mirrors/clocks that emission point is invarinat in space. teh point does not move, eeven thouigh tghe frame does move.

Look at the photon moving to the left, It moves a distance ct from where it was emitted before striking the L clock and is immediately reflected back . In another ct distance the photon is back at the exact point in space from which it was emitted, The photons define the zero point coordinate system. it defines a common velocity = zero point. Notice that the right moving photon does not strike the R clock in the first ct distance it travelled, therefore the photons do not arrive at the clocks simutaneously. Hence, the light may be measured nonisotropically i.e. that the speed of light changes from frame to frame. or at least the effective measured speed changes, It doesn't change the speed ofof light, as what is emasured is the relative velocity of frame and photon.

SRT says unambiguously and with fervor that the photons will arrive at the L and R clocks at the same time from teh perspective iof the observer on the moving frame.. Do you believe this?
,
The physical location of the midpoint changes with motion, but not the point the photons were emitted.

Because the left photon is moving to the L clock which is nmoving toward trhe oncoming light the light will strike the L befotre the right moving photon strikeas the R clock that is moving away. Special relativity does not recognize that the left phootn can be considererd moving at a velocity of C + V, and that the right photon moving at c - v. This says to the SRT crowd that the speed of light is not isotropic, that is that the speed of light is measured here as c + v and c -v, as if the speed of light was being increased or decreased, when al it measnis a measure of the relative veloicty iof rame and photon.

Isotropic means the speed of light is conmstant and measured as C for all frames of reference. What is not considered is that the c = V and c - V terms are merely statements describing the diffeence in the speed of light with respect to the frame of reference.


Can you see anyway that the light can arrive at the two moving clocks simultaneously when emitted from a common point at the midpoint of the clocks, if the frame is moving?

Brief enough? So Atheist, are you waiting fior Godot?
Geistkiesel

[geistkiesel]

Quote

I am just reading about the Sagnac effect now, it will be interesting to see how long it takes me to understand it.

Apparently, in 1913 French scientist 1869-Georges Sagnac-1926 came up with a way to modify the Michelson Morely experiment.

Here is one source which describes the "Sagnac effect", and the relevent quote: Article on Sagnac effect



Here is an article from the encylopedia Brittanica: Article2 on Sagnac Effect

Ok, so the "Sagnac Effect" is one method of measuring rotation. That I consider useful and important.

Today, optical gyroscopes (based on the Sagnac Effect) are replacing mechanical gyroscopes, because the optical gyroscopes have no moving parts.



So the "circle is turning."

The device is spinning, with some angular velocity.


"Photon's do not arrive at emission point simultaneously"

Well of course not, because the circle is turning.

Let me find a picture of it.

Here is a picture: Article 3 on Sagnac effect


This is interesting:




Everyone's thoughts on this appear somewhat scattered.

Somewhere in the universe is the center of mass of the universe.


Set up a rectangular coordinate system, with that point permanently fixed at the origin.

Now, there are stars everywhere, in that frame. If the frame is spinning wildly out of control, then to an observer whose location is fixed in the frame, it will appear as if the stars are spinning out of control.

And this will show up in his calculation of the total kinetic energy of the universe.

But in just the right frames, the centers of mass of various galaxies obey Galileo/Newtons Law of Inertia.

All such frames will be inertial reference frames.

Now, the quote above, says that Sagnac rotated his turntable at two revolutions per second.

Then it says that he "found the expected effect."

Then the caption makes reference to "absolute rotation."

Here is something interesting about Physicist H.E. Ives: Article making reference to Ives



Cross with this source:




Right now, I am reading the source which you said was excellent:

Article

Ok I am focusing on the mathematics, which is accompanied by figure 2.

The Circular Sagnac Effect

They use the symbol t₀ for the time taken for a photon to travel around the circular path, when the motor which causes the device to rotate is off.

I have a good book (Numerical Methods For Scientists And Engineers-1962) on the finite discrete difference calculus, written by R.W. Hamming, and the difference calculus would use Delta t, for an amount of time. So I am just going to switch that to:

Dt₀

So this denotes an amount of time, which is measured by a clock at rest in a frame attached to the surface of the earth, and the measurement is made when the device isn't spinning in the frame.

For whatever it is worth, the Hamming code is named after him.

Richard Hamming

His book is really good, and influenced me mathematically so to speak.

So now, let there be a coordinate system at rest in this frame, with its origin at the center of the circle, and the circle lying in the XY plane of the frame.

Now, the photon will have some speed in the frame. Denote that speed by v. I deliberately did not choose c to denote the speed.

So v is the speed of a photon, as defined in this frame of reference and no other.

Now, let us presume that the tangential speed of the photon is uniform in this frame. The tangential speed of the photon is constant, but the velocity of the photon in this frame is changing. The photon is travelling in a circle, with radius R.

So the photon has a nonzero centripetal acceleration, related to v, and to R as follows:

a_c = v²/R

Distance around the circle = 2 pR

And speed = distance traveled/travel, hence:

v = 2 pR/Dt₀

Assuming that the speed of the photon isn't zero in this frame, we can divide both sides by v to obtain:

Dt₀ = 2 pR/v

The article then makes reference to the time measured aboard the spinning disc t`.

I need to think about this carefully.

From the diagram, the photon which moves against the rotation, reaches the detector before the photon which moves with the rotation, assuming that the two photons began their circular journey simultaneously, and have the same speed in the earth frame.

Let the constant angular speed of the device in the earth frame be represented by w.

Let the tangential speed of the device in the earth frame be denoted by v_t.

The tangential speed of a point fixed on the rotating disc is related to the angular speed in the earth frame, and the radius of the disc as follows:

v_t = wR

Let t1=0 denote the moment in time, at which the two photons begin their circular journey.

Later, the device will have rotated through some angle =q, at which moment in time, the photon moving against the direction of rotation will be back at the starting point(the detector).

Call this moment in time t2.

So this is an event, marked by two moments in time t1,t2.

I will represent this event by the notation [t1,t2].

Now, during the event [t1,t2], the total distance which the photon traveled in the earth frame, is less than 2 pi r.

Focus on the circle in figure 2(labeled "Whole apparatus turning at w clockwise").

There are two sectors to focus on. One bounded by circular arc SS`, and a larger sector bounded by circular arc SS``.

Call the photon moving counterclockwise photon A, and call the photon moving clockwise photon B.

So the total distance traveled by photon A, during event [t1,t2] is given by:

2p R - Rq.

Where theta is the angle subtended by arc SS`.

Now, let the amount of time which this took, as measured by a clock at rest in the earth frame be denoted by:

Dt1

And a small amount of time later, photon A will have traveled a full circle, in the earth frame.

Let us denote this amount of time by:

Dt2

Lets add the two times together to obtain:

Dt1 + Dt2

And this is the amount of time, that we previously denoted by:

Dt₀

Therefore:

Dt₀ = Dt1 + Dt2

;

'

Look at the schematic, The math is much simpler when breaking the motion into the 0,1,2,3 sections as you see, The difference in the total round trip tiome of the photons compared tot he experiment copnmducted in a stationary frame of refrerence, is derived from the right photon after moving a distance initially of, ct. THis photon will arrive at R after travelling another distance 2vt plus a small distance vt' that the frame move when the photon acrosses this litle 2vt space, t' turn out to be the added time for the round trip of the photon from emission to the simultaneous arrival back at the physical midpoint of the frame.as compared to the experiment being conducted in the stationary frame. ct' = 2vt + vt'' you can do the algebra to extract the t' term.

Johnny5, You seem to have grasped the matter quite thorughly. The schematic in pretty colors I posted is "half a circular Sagnac" set up,. One of the references points to the finding that whether the measurements were made from the moving frame or the lab the results were identical. My schematic is merely a "lnear Sagnac" machine. It was discoverd that the SE is not just a rotational effect, it is in effect concerning the velocity of moving measuring devices and the relative speed of frame and photon that is not measured as C always. In other words SRT has negated the concept of velocity when measuring the speed of light aby asserting traht all moviong frame s will always measure the relative velocity of frame and photon as c. Silly isn't it?

The papers are more in accord with each other thna you statement below describes. After all they are identifiable humans each with a unique personality being manifest describing what hhey think is useful and benefical, significant. Their individual terms vary, but they are really together theoretically.

If you haven't grasped what I considerd the "major" point is that the emitted photons define a zero-point corrdinate system, with a physically defned origin. From here velocity can be measured with respect to zero velocity, absolute zero velocity as the emission point does not move. The physical device from which the photons were emitted moves, but the zero-point, ZP is an abstract eternal location in space from which all motion can be referfenced. You can appreciate the problems such devices make for SRT ists? This device is the highest form of heresey!!


Good post. BTW, how and where did you prove your statement regarding the use of Gallilean coordinate systems being universally proper re EM radiation? Swansont gave you short shruift on your mathematical work. Where is the paper I aseek? The coordinate system here is such a system.

Caveat Emptor regarding responding to SRT supporters, they will try to distract you answerin bs questions to throw your focus away from SRT.

Geistkiesel

[Johnny5]

Quote

The schematic in pretty colors I posted is "half a circular Sagnac" set up,. One of the references points to the finding that whether the measurements were made from the moving frame or the lab the results were identical. My schematic is merely a "lnear Sagnac" machine. It was discoverd that the SE is not just a rotational effect, it is in effect concerning the velocity of moving measuring devices and the relative speed of frame and photon that is not measured as C always. In other words SRT has negated the concept of velocity when measuring the speed of light aby asserting traht all moviong frame s will always measure the relative velocity of frame and photon as c. Silly isn't it?

I briefly looked at your pretty colored diagram, and understood it.

If the linear device was at rest in the zero point frame, then the two photons would be detected simultaneously.

Instead the device was moving.

Now, I just have to pay attention to the mathematics, which I will get around to.

You are quite good you know

Kind regards

[timo]

Sry, but it seems you misunderstood my last post a bit. I wasn´t asking for the setup to be explained again, I was asking what this is all about. Well, from what I understood so far I can give you two remarks:
- The "invariant point in space" still makes no sense to me. Within the scope of relativity points are spacetime-events which implies that they have a time associated to them. Loosely speaking points only exist at a certain time. Hence, the thing about a point moving in space becomes rather meaningless. One might construct something like equivalence classes of points that are representation of each other for different times but this would be a frame-dependant assignement because the time I speak of in this case is frame-dependant. And frame-dependant expressions are not really elegant and should be avoided (which is not allways possible).
- I get the impression that you think this experiment disproofs relativity because relativity said the two photons must allways arrive at the same time or at least with the same time-difference. That´s of course not true. Events (=Points in spacetime) seperated by a spacelike distance can have any order in time if you chose a suitable frame of reference. In fact, one could claim that this is the reason the whole thing is called Theory of Relativity. Btw.: Of course I think that the photons arrive at the same time in a reference frame in which L and R are at rest. Everything else wouldn´t make much sense, as far as I can see it.

What´s "Godot" ?

[geistkiesel]

[quote name='swansont']If you have actual scientific objections, by all means post some citations. It has been my experience that the nebulous objections posted are often taken out of context, and context is important. So is defining unusual terms and words, like "mathematiocal structure"[/quote]

Good point. I use the term somewhat generically to mean the mathematical models of SRT, or what ever I am discussing, no more no less.

[quote name='Swansont']The deviation of the earth from being an inertial frame is quantifiable, as I have discussed elsewhere. Approximating it as one can be done, as long as the effects of rotation can be shown to be small. It's a matter of degree.[/quote]

I agree here. If we just coinsider the daily rotation of the earth frame we see a rotation rate of approximately 360/24x3600 = .0042 degrees / sec. Would not making any measurement within this limit negate the turning motion of the earth regarding the measurement of light, in most parcticalapplications?

Also, whgen a relative motion between the embankemnt, Ve and any other recogniziable object, say Vf, it is always the Vf seen to accelerate wrt Ve, never does Ve contribute any accelerated or otherwise measured motion to the realtive velocity of Ve wrt Vf. For massive physical objects the Ve can be considerd a perfect Ve = 0 frame of reference, an inertial frame. Now when an observer sees himslef stationary wrt Vf and consideres himslef at rest wrt Ve using gthe equivalnce of inertial frames as justification I see some serious problems.

If Vf assumes a state of rest he is assuming a physical impossibility. Emankments do not accelerate and add motion to the measured relative velocity ergo all the realtive motion resides in the accelerated Vf frame. As Vf observers are equally justified in assuming themselves moving and the Ve at rest it woul seem physically much more justified (even onkly justifierd) if this were the ONLY consideration the moving observers were to make. Virtually overnight there would be3 a return to simultaneity, absolute soace and time and rational thought supplanted by direwct observation.

To insist theoretically that the moving Vf will always measure a relative velocity of frame and ophoton as c this theoretically hegates the very concept of motion of the Vf for theory's convenience . My thread on absolute velocity zero was intended to point out the fallacy of the assumpption of the realtive velocigty of frame and photon. The speed of light is not affected by ncluding the frame motion and the gain in arriving at the "true" measured velocity of objects is predictably enormous.


I read Ashby's paper again and also read hjatch's paper again on GPS and while you may consider my conclusions biased, I vote for Hatch's version fopr any number of reasons. Mostly, however, I see a rational structure, that word again, as Hatch describes matters, nit perfectly mind you but consistentlhy. This togethetr with postulates of light that abound i can only conclude that we live in basically Newtonian world as I see it.

I have brought this subject up before and no one has jumoped on it for any kind of comments, but please humor me briefly. The sun has been measured as moving at 208 km/sec, effectively orthogonal to the rotational and orbiting motion of the planet. When the velocity vectors are summed, I get a resultant total velocity vector pointing tan[sup]-1[/sup]30.497/208 = 8.3 degrees along a general a north = souith eartyh axis line. Assuming for the sake of argument that the velocities are measured as stated, what do you see the physical affect of the rotational vector considered alone? The earth turns at one revolution /24 hours (more or less) but can the the rotational velocity vector ever be considered very significant measured separately from the sun trajectory velocity, or even the orbiting motion? Dayton Miller who reproduced the MM experiments many thousands of time over found the same result as Michelson, i.e. about 8.8 km/sec absolute velocity wrt "the ether". The effect was diurnal and left Miller shaking his head.

In twenty four hours the sun trajectory has moves 208x24x 3600 = 16 x 10[su]6[/sup] km to the earth rotation distnce of 42000 km, so where is the earth velocity vector pointing from any one spot on the surface? From what I gather, the velocity vectors seem to act independently of each other, what say you?

I have read that others have found a different direction for the solar system other than Miller's, but my question has to do mostly with the physical addition of velocity vectors of stellar objects generally, not just the ones discussed here,


[quote=Swansont]
The extent of my comments is in part a function of how much time I have to spend online. If I or anybody else does not respond to you, it may be related to how rude and condescending you are being, and how willing you appear to be to engage in honest discussion. I have no desire to waste my time in threads that are of no value to me. As for the "minimum standard of expertise that we at Science Forums expect" I rather doubt you speak for anyone else here, and I am sorely tempted to tell you where you can stick your expectations.[/QUOTE]

I more than merely understand your consternation. If I have offended you then I was out of line. I guess I just over reacted to your "for crying out loud' which was not taken as insulting or even derogatorily. I just came from a defunct forum that decided to close shop with out notice or any word, and some of the conversations there (SRT mostyly) had been quite energetic to say the least. I do not make excuses for boorish behaviour not do I attempt even to justify what is really just a common human trait that I am quite capable of avioiding. I suppose I am just a creature of habit, which I am thoroughly capable of breaking.

By the time that Custer and Sitting Bull met it was past the moment to repair distressed lines of communications, so, removing the arrows from my butt, I say lets stand tall and get this conversation running again.


Do we have a serious truce, or even an outbreak of total peace and polite discourse? I know how to excell at this as I trust you are at least an equal?

Geiskiesel :cool:

[swansont]

Quote

Dayton Miller who reproduced the MM experiments many thousands of time over found the same result as Michelson, i.e. about 8.8 km/sec absolute velocity wrt "the ether". The effect was diurnal and left Miller shaking his head.

Miller isn't the only one to reproduce the experiment. One Michelson experiment did show an upper bound of ~8 km/s, but upper bound is the key point here. There is always experimental error, and this becomes very apparent when you try to measure a result that can be zero. Many people have done the experiment since, using better apparatus. Has anyone reproduced Miller's results? If you can't reproduce the results, you have to assume that it was some systematic in his system. Why does everyone else get a much smaller upper bound for the experiment?

[swansont]

Quote

I more than merely understand your consternation. If I have offended you then I was out of line. I guess I just over reacted to your "for crying out loud' which was not taken as insulting or even derogatorily. I just came from a defunct forum that decided to close shop with out notice or any word, and some of the conversations there (SRT mostyly) had been quite energetic to say the least. I do not make excuses for boorish behaviour not do I attempt even to justify what is really just a common human trait that I am quite capable of avioiding. I suppose I am just a creature of habit, which I am thoroughly capable of breaking.

By the time that Custer and Sitting Bull met it was past the moment to repair distressed lines of communications, so, removing the arrows from my butt, I say lets stand tall and get this conversation running again.


Do we have a serious truce, or even an outbreak of total peace and polite discourse? I know how to excell at this as I trust you are at least an equal?

As long as the discussions remain civil and centered on science, I have no problem.

[geistkiesel]

Quote

Sry, but it seems you misunderstood my last post a bit. I wasn´t asking for the setup to be explained again, I was asking what this is all about. Well, from what I understood so far I can give you two remarks:
- The "invariant point in space" still makes no sense to me. Within the scope of relativity points are spacetime-events which implies that they have a time associated to them. Loosely speaking points only exist at a certain time.

I have no problem with this. The photons are emitted at a time t0 and the all of them of them returns. The point does not move, it is invariant, the point defines a zeropoint of zero velocity from which all other motion can be measured. What else does one need for an inertial coordinate frame?

[quopte=Atheist]Hence, the thing about a point moving in space becomes rather meaningless. One might construct something like equivalence classes of points that are representation of each other for different times but this would be a frame-dependant assignement because the time I speak of in this case is frame-dependant. And frame-dependant expressions are not really elegant and should be avoided (which is not allways possible).

[geistkiesel]

Johnny5, Some of the confusion goes to the use of the words "isotropic light moyion"/? There are postulates of light that assert light is constant and measured the same from all inertial frames - all relative velocity of ftrame and phootns are supposed to be measured as C. When one start using the expressions, c + v and c - v, the expressions get modified by the Safnacs who state that light is nonisogtrpoic, meaning that light can be slower ar faster than C motion in Sagnac frames. The speed of light is not changed in Sagnac frames but the relaive motion is not restericted to negaqting frame motion as demanded by SRT. Of course this is how SRT ists say that one will always measure C as the relative motion of frame and photon.Simply set the frame velocity zero in the mathematical expressions.

[geistkiesel]

swansont said:

Miller isn't the only one to reproduce the experiment. One Michelson experiment did show an upper bound of ~8 km/s, but upper bound is the key point here. There is always experimental error, and this becomes very apparent when you try to measure a result that can be zero. Many people have done the experiment since, using better apparatus. Has anyone reproduced Miller's results? If you can't reproduce the results, you have to assume that it was some systematic in his system. Why does everyone else get a much smaller upper bound for the experiment?

Swansont,
You will have to answer the question yourself. When I read Miller's paper and recognize that his 200,000 tests have not been duiplicated, certainly not with the precision that Miller took in his experimental acitivity. Muioller refers to some of the experiments hilself, and does the same shrug of the shoulders that you just did. If youare really concerned that this may jave soem scioentific value, thenj check it out is all I can offer,

Millers results also were diurnal and to my satisfaction his systematic errors were no heat caused as claimed by Shankland. Miller discusses the heat problem with more clarity and than Shankland did.

Likewise, the 8km/sec value that MM and Miller both obtained was not nrear the noise of scientiic accuracy. The 8/km number was slightly greater than 1/4 of the expectred value when considering the orbital velocity of earth at 30km/sec. However, as relative velocty had not been scrutinized with the depoth apllied by MM or M, the scientific workld was stunned at the resultant difference in the observed from the expected. What is sham,eful is the contnued reference to MM results as "null" whc the number "8 km/sec" is certainly not.

You have either misread Miller and MM or you do not understand the results. Miller systematuically ansd consistently reproduced results for over 30 years. I disagree strongly with your statement that the failure to reproduce Miller's result implies that Miller's results are corrupted by soem intrinsic experimental error. Let me correct you. The experiments that followed MM and Miller need to be scrutinized on their own merits. Your statement assumes that post Miller experiments experimental error free, which has not been shown to be the case, especially here, as you do';t know any of the paritculars one way or the other. Your statement further confuses the scientific aspects of the problem with assumptions that are definitiely biased and irrationa for your rejection of Miller out of hand, meaning with no reference to any experiomental results supporting yopu statements, You do understand what i am saying here? Obviously you fear the effect implied by Miller's results. What else could it be? Your statements certainly weren't just careless utterances, were they? You know what you are saying very clearly. You are a conscious and aware person and "8 km/sec" is a fatal shot to the heart of SRT do you not agree?


Geistkiesel; :cool:

[Johnny5]

Quote

"8 km/sec" is a fatal shot to the heart of SRT do you not agree?


Geistkiesel; :cool: [/indent]

What is moving at 8 kilometers per second, and in what frame?

Regards

[Johnny5]

I have been reading the article on the circular sagnac effect, and I think the following formula in the article is wrong:

The Sagnac Effect and Uniform Motion

t’ = 2pr/(c + v) (equation 3 in the article)

I am only just beginning to think about it now.

Multiplying both sides by (c+v) gives:

t’ (c+v) = 2pr

Distributing amount of time t`gives

t’c+vt’ = 2pr

The problem I have is with the RHS.

The photon hasn't really travelled in a full circle of radius R.

And the reason is certainly clear, the disc is spinning.

To help me understand this better, I am thinking of a tiny marble, on a frictionless disc of ice, with no friction whatsoever.

Then the disc starts spinning, as if someone turned a record player on.

Because there is no friction, the marble remains at rest in an outside frame.

Yet to an observer anchored to the spinnin disc, the marble "appears" to have travelled in a circle.

But, a frame fixed to the ice disc, is a non-inertial frame.

In particular, if an observer fixed to the ice disc completely disregards external objects (which too appear to be orbiting)

The marble appears to have a centripetal acceleration.

But the net force on the marble is zero.

So something strange is going on in the physics of this.

You can see it as you switch from the record frame, to the inertial frame, and back again.

I would be the first to argue that you can do physics in any frame, inertial or otherwise, but you need to have transformation formulas.

At any rate, right now I am only concerned with their equation (3).

Here it is again:

t’ = 2pr/(c + v) (equation 3 in the article)

The writer also says that t' is the time on the spinning disc, as if time is different there, as opposed to measuring time using a clock, at rest in an inertial frame, which clock is necessarily external to the disc.


t’c+vt’ = 2pr

I think the simplest way to clear up the problem is to use the precise definition of "relative speed" which ironically is an absolute in all frames.

You know, there is the same problem with measurements made on earth, as is going on on the record player.

The stars don't stay fixed in the sky.

I can do this correctly, but I just need to think for a few moments carefully.

Let me refer to the external frame, as frame F.

When the motor is off, the disc isn't spinning in frame F.

Now, suppose that the following experiment is performed in frame F.

Somehow, a photon is fired, and made to go around the circumference of the "record player" in time

Dt₀

as measured by a clock at rest in frame F.

Maybe frame F is inertial maybe not, but that is the measurement by the clock.

Now, using a "meter string" the circumference of the record player is measured to be:

2p R

So we have two solid measurements in the frame, and we define the ratio of them to be the tangential speed of the photon in frame F. That is:

v_t= 2p R/Dt₀

Now, we can relate the tangential speed, to dq/dt as follows:


v_t= Rw

w = dq/dt


Ok firstly...

The circumference of the record player is stipulated to be an absolute in all frames of reference.

Now, if we turn on the record player, and the marble remains at rest while the record player turns, after some time T has elapsed (as measured in F), the marble will again coincide with the starting point (which is just a mark dug into the record).

WE could also give the marble a "push," and if there is a lip around the record players perimeter, the marble would travel in a circle in frame F (instead of remaining at rest in frame F), in some amount of time which could be measured by a clock at rest in F.

So these are the kinds of measurements we can make.

The case of the Sagnac device is interesting for the following reason:

Not only is the photon traveling in a circle in frame F, but the disc is spinning as well.

Ah HAH!

Ok so now, in symbolic imitation of the article, let us do this:

c = 2p R/Dt₀

Now, that isn't necessarily 299792458 meters per second, it is whatever quantity is obtained upon taking the ratio of the measurements (as already described). I chose the letter c, because the author of that article used the letter c for that ratio. At least this way, I can check what they are doing.

So when the device isn't spinning you get whatever you get for c, as measured by devices at rest in frame F.

Now let me glance at the article.

Their very next step is to simply write the following formula:

t’ = 2pr/(c + v) (equation 3 in the article)

I would much prefer to write things in terms of dq/dt, and attempt to derive that formula, rather than simply pull it out of thin air.

For what it is worth, that is the first time that symbol v is brought into their argument, and the author calls it "speed of a point on the periphery of the disc."

If you are rigidly attached to the disc, then all points on the disc have no speed relative to you, so that v which they introduced, has to be the speed of a point fixed to the edge of the disc, and that speed is defined in frame F, which is external to the disc.

And that speed is appropriately the tangential speed of the disc, in frame F.

So forget about the photon, and focus on the disc.

The center of inertia of the disc is at rest in frame F.

But a fixed point on the periphery of the disc completes one revolution in T seconds.

Thus, the tangential speed of a periphery point in frame F is given by:

v_t= 2p R/T = Rw

where

w = dq/dt


Now, what is really going on is this...

At the moment in time that the photon has completed one circular revolution in frame F, a fixed point on the perimeter has advanced through some total angle Q

And the amount of time this happened in, is the amount of time it took the photon to make one revolution, in frame F, which is the period of the photon.

The period of the photon in frame F was denoted by:

Dt₀

This is different than the period of the spinning disc, which was denoted by T.

Now, the moment in time at which the event began was denoted by t1.

And, the moment in time at which the photon completed one revolution in frame F was denoted by t3.

And so the amount of time of event [t1,t3] is Dt₀

Now, the tangential speed of the disc was denoted by

v_t

v_t= 2p R/T = Rw

And

w = dq/dt

Therefore:
v_t= 2p R/T = R dq/dt

So, let us stipulate that the tangential speed of a fixed point on the record player is constant. (this has nothing whatsoever to do with the photon)

So we have this:

v_tdt= 2p R/T dt= R dq

Now, we can integrate from moment in time t1=0,
to moment in time t3=t1+ Dt₀

The total change in angle, the integral of dtheta, has been denoted by:

Q

So, we have:

(2p R/T) Dt₀ = R Q

Now, I need to connect this to what they call t`. Here is their quote:

Quote

Referring to Figure 2, and taking t0 as the time observed when the disc is stationary, i.e. the path length divided by the speed of light:
t0 = 2pr/c (2)
The time t’, as observed aboard the spinning disc, for the counter-clockwise beam to complete a circuit, is
t’ = 2pr/(c + v) (3)
where v is the speed of a point on the periphery of the disc.
The difference between the two equations (2) and (3) is:

So the difference in time (dt’) between the stationary and the anticlockwise cases is:
dt’ = (t0 - t’) = t0v/(c + v) (4)
For the other direction, where t” is the time for the clockwise beam to arrive back at point S”, the difference (dt”) between the stationary and the clockwise case is similarly:
dt” = (t” - t0) = t0v/(c - v) (5)

So t` is the amount of time it takes the counterclockwise moving photon to travel from the detector around and back to the detector.

And this has to be less than the amount of time Dt₀, you can just figure that out from their diagram.


So my question now, is how do I figure it out. In other words, I now need the time of the following event [t1,t2] using the variables already introduced.

I see very clearly their solution, but I am not the type to use something I cannot either outright understand, or derive myself. What bothers me is that they have the distance traveled as being 2piR, but that isnt the case.

There is something significant here about spinning frames, but I can'tquite put my finger on it.

If you permit yourself to switch between the two frames, then you can make sense out of things, but you have to be very careful about using the definition of speed.

I'msure if you've already solved the problem it's a piece of cake, and I've solved this one before, probably over 15 years ago. Its been so long I have to redo it.I think it was in a book on classical mechanics by Kleppner/ Kolenkow, a book used at MIT. They solved this or something similiar.

It probably didn'tmake sense the first time, which would explain why it didn't keep.

If you are willing to define the speed of the photon, in a frame fixed to the record player, then the photon will have a greater speed in that frame, then in frame F.

And the reason is obvious. You will use 2piR for the distance traveled, and the same amount of time as measured in frame F for event [t1,t2] but in frame F, the distance traveled by the photon is less than 2 pi R, in the same time, as passed in the spinning frame. And hence the speed of the photon in frame F, will be less than the speed of the same photon in the spinning frame. But of course, this has turned distance traveled into something meaningless.

Special relativity is the least of my concerns right now.

Well let me see if I can at least get their formula for t`.

[swansont]

Quote

Swansont,
You will have to answer the question yourself. When I read Miller's paper and recognize that his 200,000 tests have not been duiplicated, certainly not with the precision that Miller took in his experimental acitivity. Muioller refers to some of the experiments hilself, and does the same shrug of the shoulders that you just did. If youare really concerned that this may jave soem scioentific value, thenj check it out is all I can offer,

Millers results also were diurnal and to my satisfaction his systematic errors were no heat caused as claimed by Shankland. Miller discusses the heat problem with more clarity and than Shankland did.

Likewise, the 8km/sec value that MM and Miller both obtained was not nrear the noise of scientiic accuracy. The 8/km number was slightly greater than 1/4 of the expectred value when considering the orbital velocity of earth at 30km/sec. However, as relative velocty had not been scrutinized with the depoth apllied by MM or M, the scientific workld was stunned at the resultant difference in the observed from the expected. What is sham,eful is the contnued reference to MM results as "null" whc the number "8 km/sec" is certainly not.

You have either misread Miller and MM or you do not understand the results. Miller systematuically ansd consistently reproduced results for over 30 years. I disagree strongly with your statement that the failure to reproduce Miller's result implies that Miller's results are corrupted by soem intrinsic experimental error. Let me correct you. The experiments that followed MM and Miller need to be scrutinized on their own merits. Your statement assumes that post Miller experiments experimental error free, which has not been shown to be the case, especially here, as you do';t know any of the paritculars one way or the other. Your statement further confuses the scientific aspects of the problem with assumptions that are definitiely biased and irrationa for your rejection of Miller out of hand, meaning with no reference to any experiomental results supporting yopu statements, You do understand what i am saying here? Obviously you fear the effect implied by Miller's results. What else could it be? Your statements certainly weren't just careless utterances, were they? You know what you are saying very clearly. You are a conscious and aware person and "8 km/sec" is a fatal shot to the heart of SRT do you not agree?


Geistkiesel; :cool:

You're correct in that I don't know all the particulars one way or another. But I note that you have not provided any particulars, either, in support of any of your claims.

Being able to reproduce results is one of the cornerstones of science. It's why Pons and Fleischmann are no longer employed at the same address as they were before the cold fusion incident. When you get one result and the rest of the world doesn't, you have to wonder why. From what I've read, Miller did his experiments basically in a tent because he was convinced of ether shielding, yet others did experiments to test if there was such an effect and came up empty.

When I said "systematics" this is not the same as random experimental noise. It means a bias in the mechanism that skew the results in one particular direction. Lots of things can give diurnal results, and if you really have a diurnal effect, it's damn hard to separate all of them out an isolate the one in question. Basically you seem to be proposing that he got it right and everybody else is wrong, and that despite the trend that as equipment gets better and better over time, so do experimental results. You're trying to buck the odds twice.

8 km/s is not a "fatal shot" for a few reasons. It has been shown to be an anomoly, first of all, by the numerous other experiments. Show why the others don't come up with the 8 km/s result. Another reason is stellar aberration, which shown that we cannot be moving at some speed other than 30 km/s. That's the result you have to measure, not "any value other than zero."

[timo]

Quote

[indent]
I have no problem with this [point being only defined at a certain time in SR]. The photons are emitted at a time t0 and the all of them of them returns.

They can only return to the emmision point if they manage to travel backwards in time or with infinite speed. Neither is possible in SR.

Quote

The point does not move, it is invariant, the point defines a zeropoint of zero velocity from which all other motion can be measured. What else does one need for an inertial coordinate frame?

The point doesn´t move indeed. Because you need something to be defined at more than one time to associate movement to it.

Quote

I thought the frame dependence was avoided and that the inertial frame (having nothing to do the hardware or massive objects) was the result.

Just to be certain: Are you aware that there is an infinite number of inertial systems? Each system moving with a constant velocity wrt an intertial frame is also one.

Quote

I had the vison that the production of absolute motion, including absolute zero velocity was a trivial task to produce.

Absolute velocity is called 4-velocity and does exist indeed. But I´m afraid it´s not really what you mean with absolute velocity.

Quote

Quote

No the time difference is never the same "delta". It is always simultaneous. At least that is what the loudest of the SRTist are saying.
That´s of course not true.

Why did you quote me with that? I neither understand it nor did I say this. Got the html-tags wrong when trying to answer on my post?

A sidenote not related to any particular statement of yours: As long as you are talking about space and not spacetime when trying to talk about SRT you are actually calling for problems and mistakes.