Laser curvature test on lake Balaton

[Sensei]

We made this calculator for imperial units:

Couple things to reconsider:

 

- Earth has no constant radius, 6371000 m is average. For a start you could calculate varying radius using GPS latitude.

See "Location-dependent radii" section

https://en.wikipedia.org/wiki/Earth_radius

 

- Because of slightly non-spherical shape of planet, pointing laser north-south line, won't have the same result as east-west.

 

- Lake Balaton surface elevation is 104.8 m.

[storrence]

If you record and plot height against distance then it's not important if the laser is level or pointing slightly up since the data will mirror the shape of the surface when plotted.

Couple things to reconsider:

- Earth has no constant radius, 6371000 m is average. For a start you could calculate varying radius using GPS latitude.
See "Location-dependent radii" section
https://en.wikipedia.org/wiki/Earth_radius

- Because of slightly non-spherical shape of planet, pointing laser north-south line, won't have the same result as east-west.

- Lake Balaton surface elevation is 104.8 m.

Are you suggesting this deviance is 1/2 km in 77km? Here is the elevation map of the area.

Edited September 11, 2016 by storrence

[Mordred]

This thread reminds me of the Bedford level experiment. A key detail came out of that experiment. Laser light path close to the surface will follow the mean curvature of the Earth due to density of the atmosphere.

 

Atmospheric refraction is significant and can cancel out the surface curvature. Changes in Atmospheric density distribution has significant influence. Its not just atmospheric temperature variation though that can also generate refraction.

 

I might have missed it but did you calculate the level refraction curve?

The standard used on survey equipment which I have some experience with is

 

[latex]\Delta h_{metres}=0.067 D^2_{km}[/latex]

 

this value is a combination of curvature and refraction index.

 

Seems to me your making the same error assumptions as the Bedford experiment.

 

Just noted the wiki link on the Bedford experiment gives the same formula. (makes sense)

Edited September 11, 2016 by Mordred

[storrence]

The laser was 1.25 above water level. That is above any supposed light bending due to refraction. With the conditions of the morning, refraction would have been up, not down. Air temp was cooler (denser) than water at the time of the measurements.

[Mordred]

no your looking at refraction due to temperature turbulance.

 

This isn't the only source of refraction. The laser is moving through a medium. The properties of medium density alone will cause refraction downward due to density profile.

 

Its the same effect as laser light through water... the light will curve towards higher density...

 

Your mistaken assumption is that identical temperature at two locations imply a straightline path for the laser.

 

This is false. The density profile alone causes refraction.

Edited September 11, 2016 by Mordred

[michel123456]

This thread is a waste of time

 

 

I assume (as it has been completely obvious for many millennia that the world is round) that you are simply trying to understand why your experiment produces the wrong results.

No. He is a flat earther. He is not searching for a flaw. He wants to make points on this forum (getting upvotes from friends) and use it afterwards as a reference (that nobody could debunk the experiment).

IOW it is a trap.

[swansont]

This thread is a waste of time

No. He is a flat earther. He is not searching for a flaw. He wants to make points on this forum (getting upvotes from friends) and use it afterwards as a reference (that nobody could debunk the experiment).

IOW it is a trap.

!

Moderator Note

Let's stick to the subject matter, rather than guessing at motivations.

[John Cuthber]

This thread is a waste of time

No. He is a flat earther. He is not searching for a flaw. He wants to make points on this forum (getting upvotes from friends) and use it afterwards as a reference (that nobody could debunk the experiment).

IOW it is a trap.

It's trivial to debunk his experiment: it gives a result that implies the Earth is flat. we know that the Earth isn't flat* so there is something wrong with his experiment.

 

* Anyone with a map of the world and a set of international flight timetables can prove this.

 

However the interesting bit is to work out where he has got it wrong.

So far,, he's ignoring gravity (which makes warm gases rise)- which is interesting, even if it's only a small effect..

[Mordred]

He has also ignored the vertical refraction index at various elevations and atmospheric pressure gradients. Here is a decent coverage.

 

https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.jhuapl.edu/techdigest/td/td1703/thomas.pdf&ved=0ahUKEwjQ4eGm-4fPAhVPw2MKHQHOD7gQFggbMAA&usg=AFQjCNExj-XJr5shUPJwicy1Dbn9NFpjeQ&sig2=AYgAJ6VxpOJRmr88nPUblg

 

Though I'm not positive this is the best article but it reflects ( no pun intended) the principle.

 

In an oversimplified nutshell temperature/pressure/density follows the curvature causing a refraction index along the curvature profile.

 

This holds true even if we assume no other turbulance temperature/pressure influence. (anistropic variations)

As reflected in the above article.

 

A preliminary framework is Snell's law but unlike the prism. Where the refraction index is constant in a straight line. In the atmosphere a constant index would follow the curvature.

Edited September 11, 2016 by Mordred

[studiot]

I have quite a few comments yet to make, but I'm stuck with this windows 10 piece of c___p and I don't propose to fight it tonight.

 

I do reiterate that refraction is a red herring here, the effect is too small to argue about.

 

Further correct observational methodology will eliminate it.

So we need to know more information about this.

 

I am concerned that the OP says he can only place 5 answers and is up to his quota for the next 10 hours (5 now) so I await his answers with interest when they come.

 

Think also about this methodology on the boat mentioned.

 

On land the principal source of levelling error is due to non perpendicularity of the staff.

Some part of the apparatus appears to have been mounted on the mast or similar of a boat, which must pitch, yaw and roll.

How was the non perpendicularity of the mast taken into account?

[Strange]

The laser was 1.25 above water level.

 

 

1.25 mm? inches? miles? light years?

 

 

 

That is above any supposed light bending due to refraction.

 

Refraction happens at all altitudes.

 

 

 

With the conditions of the morning, refraction would have been up, not down.

 

Please show how this was calculated and what the result was.

 

 

 

Air temp was cooler (denser) than water at the time of the measurements.

 

The temperature of the air relative to the water appears to be irrelevant.

 

With this combination of sloppiness and apparent lack of basic knowledge of physics I am not surprised your "experiment" gets inaccurate results.

On land the principal source of levelling error is due to non perpendicularity of the staff.

Some part of the apparatus appears to have been mounted on the mast or similar of a boat, which must pitch, yaw and roll.

How was the non perpendicularity of the mast taken into account?

 

 

Indeed. I imagine that the only way to maintain the necessary stability and level would be with some high quality gyroscopes and gimbals.

[Mordred]

 

I do reiterate that refraction is a red herring here, the effect is too small to argue about.

 

Further correct observational methodology will eliminate it.

 

assuming perfect conditions at refraction index for air =1. A quick back of envelope calculation is roughly 924 cm at a distance of 77 km. Granted I don't have the required details of atmospheric pressure and humidity etc. (extremely rough calc) Edited September 11, 2016 by Mordred

[studiot]

The maximum stated observational distance was 720 metres

 

Further the article is entitled 'over 6 km', which I think was broken down into small observational legs, with full calculational closure.

 

That is certainly the way I would have tackled it, and one of the details I await confirmation (or otherwise) of.

[Mordred]

I agree greater detail is needed, I only looked at the variation over the overall distance that he posted in the OP. In particular the corrections at each position as well as the systematic errors.

 

The above works out to roughly 12 cm/km

 

Considering the Earth curvature is roughly 8 cm/mile...

 

(of course this isn't linearly additive)(I'm being extremely lazy in my calcs lol)

 

I would say the refractive index is extremely important. I'm certainly not going to run these calcs for the humidity/temperature on that chart.

 

Thats the OPs option. It can have a significant influence.

Edited September 11, 2016 by Mordred

[studiot]

I agree greater detail is needed, I only looked at the variation over the overall distance that he posted in the OP. In particular the corrections at each position as well as the systematic errors.

 

The above works out to roughly 12 cm/km

 

Considering the Earth curvature is roughly 8 cm/mile...

 

(of course this isn't linearly additive)

 

I would say the refractive index is extremely important. I'm certainly not going to run these calcs for the humidity/temperature on that chart.

 

Thats the OPs option. It can have a significant influence.

 

Refraction may or may not be significant, depending upon circumstance.

 

Here is a circumstance when it is definitely significant.

 

 

This really happened in the early days of pipeline alignment lasers during the construction of the Alaska pipeline.

As Robert Service says, it gets a mite chilly up there.

However the air in the main trench was warmer and stable.

 

Except where a cross trench entered.

 

This deposited cold air as a block like the perspex one in the pic across the main trench and cause a similar offset in the laser alignment line.

 

This however was not what I was referring to here

 

 

studiot

Further the article is entitled 'over 6 km', which I think was broken down into small observational legs, with full calculational closure.

 

Some time after the pipeline event, I was working on the construction of a new factory to make car engines.

This was basically a large shed with a roof supported on a grid of stanchions.

A laser had been used by the contractor to establish benchmarks on these stanchions.

The contractor had not considered earth curvature or atmospheric refraction worth allowing for.

 

The factor housed a number of flowline machines several hundred metres long that required to be level to a couple of millimetres.

 

Being the suspicious so and so that I am I did not trust these all to convenient benchmarks so I obtained a bag of coach bolts and set one into each base as they were cast, at about 15m intervals.

After they were set I connected them as my own benchmarks to the others.

In this way I carried a system of benchmarks across the building floor and used them to construct the machine bases I had responsibility for.

 

By the far side of the building, there was a discrepancy between my bolts and the laser of 12mm.

 

I had calculated the curvature as 15mm across the building, reduced by refraction to 13mm.

 

All the bases constructed against the laser had to be recast.

 

It was a system similar to this I was referring to for the OP hydrographic survey.

 

Note also it is very bad practice to refer to the corrections as X per mile or per km because the corrections are proportional to the square of the distance, not the distance itself.

This is why such surveying is best conducted in a series of short legs as I have already indicated.

[Mordred]

"Note also it is very bad practice to refer to the corrections as X per mile or per km because the corrections are proportional to the square of the distance, not the distance itself."

 

Exactly, like I stated I was being lazy lol...

 

Your last example is an excellent one. I fully understood where you were going on the incremental measurements. Sure highlights the cost of ignoring curvature and refraction in construction applications lol. +1.

 

One class I had was sighting a laser at a building. During various temperatures and humidity measure the change. We used a 1 km distance. Its surprising how much variation you can get...

Edited September 11, 2016 by Mordred

[Sandor Szekely]

I have quite a few comments yet to make, but I'm stuck with this windows 10 piece of c___p and I don't propose to fight it tonight.

 

I do reiterate that refraction is a red herring here, the effect is too small to argue about.

 

Further correct observational methodology will eliminate it.

So we need to know more information about this.

 

I am concerned that the OP says he can only place 5 answers and is up to his quota for the next 10 hours (5 now) so I await his answers with interest when they come.

 

Think also about this methodology on the boat mentioned.

 

On land the principal source of levelling error is due to non perpendicularity of the staff.

Some part of the apparatus appears to have been mounted on the mast or similar of a boat, which must pitch, yaw and roll.

How was the non perpendicularity of the mast taken into account?

Hey Studiot I am back - the veil lifted on me

 

so far:

 

I agree that the refraction effect is marginal and bendig upwards direction so this will not effect the outcome of the experiment at our accuracy.

 

I think we should discuss the measurement accuracy: we have a difference of meters on the longest distance measurements.

 

to the other comments:

Please ask questions, and be carefull to use exact definitions and numbers (I am refering to curvature drop at 8 INCHES / miles squared)

 

 

[Strange]

be carefull to use exact definitions and numbers

Quite

 

The laser was 1.25 above water level.

[Mordred]

I agree that the refraction effect is marginal and bendig upwards direction so this will not effect the outcome of the experiment at our accuracy.

 

I don't agree as I don't see that proof within your paper. That was my entire point. You do not show this detail in your analysis. Hence its an assumption

This thread reminds me of the Bedford level experiment.

If you want your experiment to follow the same assumption feel free...

 

"If the measurement is close enough to the surface, light rays can curve downward at a rate equal to the mean curvature of the Earth's surface. In this case, the two effects of assumed curvature and refraction could cancel each other out and the Earth will appear flat in optical experiments"

 

https://en.m.wikipedia.org/wiki/Bedford_Level_experiment

 

please note the experiment was overturned on that same assumption.

Edited September 11, 2016 by Mordred

[Strange]

I do reiterate that refraction is a red herring here, the effect is too small to argue about.

 

 

Although, it does seem to be what caused several careless (and in some cases deluded) people to get the wrong result previously:

https://en.wikipedia.org/wiki/Bedford_Level_experiment

[Sandor Szekely]

Quite

 

8 centimeters / miles is misleading

 

1.25 is well understood as we speak in meters in the whole film

I don't agree as I don't see that proof within your paper. That was my entire point. You do not show this detail in your analysis. Hence its an assumption

If you want your experiment to follow the same assumption feel free...

 

"If the measurement is close enough to the surface, light rays can curve downward at a rate equal to the mean curvature of the Earth's surface. In this case, the two effects of assumed curvature and refraction could cancel each other out and the Earth will appear flat in optical experiments"

 

https://en.m.wikipedia.org/wiki/Bedford_Level_experiment

 

please note the experiment was overturned on that same assumption.

Well we ALL don't have to agree as it is quite impossible too.

 

We do talk about refraction in the video as if there is any possible refraction of the laser beam it is bending upwards as we have reversed atmospheric conditions at dawn than in the afternoon when the mirrage effect is possible to detect.

 

Look up terresterial standard refraction (value 0.4 millimeter / kilometer). We have marginal refraction that is upwards - I am not calculating with it.

 

We had the laser at 1.25 meters that is 4.1 feet that is NOT close to the water level and outside the NUDTZ non uniform density transition zone

[Mordred]

I know but you didn't detail the atmospheric density profile and its influence. You assumed a flat density profile with temperature influence ie inversion.

 

see the quoted section and first link paper I posted...

 

Its really your choice, personally if refraction caused previous experiments to fail and be overturned. It only makes sense to provide a detailed analysis to prevent the same thing from happening on your paper...

 

Quite frankly I didn't see a single calculation within your video etc that confirms an upward refraction due to inversion.

 

Just a side note. I don't know about you, but I just finished a flight this morning. At 30, 000 feet I can easily see the Earths curvature.

Edited September 12, 2016 by Mordred

[Sandor Szekely]

I know but you didn't detail the atmospheric density profile and its influence. You assumed a flat density profile with temperature influence ie inversion.

 

see the quoted section and first link paper I posted...

 

Its really your choice, personally if refraction caused previous experiments to fail and be overturned. It only makes sense to provide a detailed analysis to prevent the same thing from happening on your paper...

 

Quite frankly I didn't see a single calculation within your video etc that confirms an upward refraction due to inversion.

 

Just a side note. I don't know about you, but I just finished a flight this morning. At 30, 000 feet I can easily see the Earths curvature. Wonder why this is if the Earth is flat????

I have explained reversed direction of refraction so far and as well why I think that it playes no role in the measurement outcome

 

for the side note: you can not detect the curvature from a airplane - this is a typical misconception

 

http://thulescientific.com/Lynch%20Curvature%202008.pdf

 

[Mordred]

wrongo, guess your paper falls into the same mistakes...ah well it will most likely get ignored by the professional community.

Your loss..insufficient proof to counter all the evidence curvature exists.

Guess you don't wish to learn from the same mistakes others made in similar tests

I have explained reversed direction of refraction so far and as well why I think that it playes no role in the measurement outcome

 

Show your formulas and calculations for the refractive index. NOT VERBALLY explain it.

 

Calculate it. Your paper will go nowhere without those calculations. (Especially with all the evidence supporting curvature..) Your competing against professional papers that include those calculations.

 

For example the one I posted earlier. note the sea level deviation chart...

 

https://www.google.ca/url?sa=t&source=web&rct=j&url=http://www.jhuapl.edu/techdigest/td/td1703/thomas.pdf&ved=0ahUKEwjQ4eGm-4fPAhVPw2MKHQHOD7gQFggbMAA&usg=AFQjCNExj-XJr5shUPJwicy1Dbn9NFpjeQ&sig2=AYgAJ6VxpOJRmr88nPUblg

 

see equation 3. Why does your results deviate from that study? Whose study is more accurate? Show the proof your study is... Prove that radius is zero in that equation...

Edited September 12, 2016 by Mordred

[MrMaker]

Dear Visitors

 

...

 

Note: that the GE model curved water surface expected laser beam height does not match the observed height.

The accuracy of the test is negligable to the difference of the calculated and measured value.

 

measurement final.png

 

...

 

I can notice from your video in Youtube that your measuring white board is around 1.35m high.

 

How did you take your measures starting in row 15 in your table as those are all higher than 1.35m? After 12min in your video the laser is not hitting the white board anymore ...

 

I also noticed the beam diameter in the white board getting bigger and bigger. At around 14min the circle is nice and small. At around 19:10, the circle is barely recognizable. How did this "spread" impact your measures? How did you estimate the correct beam height as it was not nice and small anymore?

 

Great structure you put there by the way.

Edited September 12, 2016 by MrMaker