Debunking the Ghostly Swing Phenomenon in a Small Town in Argentina

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In a small town in Argentina, a phenomenon dubbed "The ghostly swing" has garnered significant media attention. The swing, located in a playground, exhibits unusual swinging behavior that has sparked various theories regarding its cause. Some speculate it could be due to wind effects, suggesting that the swing's design allows it to catch the wind like a sail, while others propose the possibility of a hoax. Observations indicate that only the middle swing moves, despite similar wind conditions affecting adjacent swings. Investigations by a local UFO group, Vision Ovni, have ruled out electromagnetic forces and wind as primary causes, although their methods and credibility have been questioned. Measurements of wind speed and environmental conditions have been conducted, but the results remain inconclusive. Theories about the swing's mechanics include the idea of resonance and the influence of chain length differences, which could affect the swing's motion. The situation continues to intrigue both locals and online discussions, with calls for more rigorous scientific investigation to understand the phenomenon better.
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A hoax is of course a possibility, but somehow that behaviour reminds me of the rattleback. It rotates back and forth around the vertical axis at the same time it starts swinging. Could it be that something tricky happens with the chains, and it is taking energy out of the wind?
 
C'mon! The wind-noise in the microphone of the video cam is deafening. Is it a little bit possible that the seat of that swing is acting like an air-foil? Let's see the hoaxters (or the incredibly gullible) film the swing on a calm day.
 
But there's something tricky happening, because only the middle one starts to swing. The wind is the same for them all.
 
jostpuur said:
But there's something tricky happening, because only the middle one starts to swing. The wind is the same for them all.
Do you think that somehow, the sling-type seats of those mass-produced swings are shaped exactly the same? I'm not willing to make that assumption.
 
I mentioned the possibility of the wind causing this in my first post, so certainly, it is not my point to start proving that wind would not be the cause. But what I'm saying is, that that is still a non-trivial phenomenon. Resonance seems to be a key issue at least.
 
jostpuur said:
I mentioned the possibility of the wind causing this in my first post, so certainly, it is not my point to start proving that wind would not be the cause. But what I'm saying is, that that is still a non-trivial phenomenon. Resonance seems to be a key issue at least.
You need to factor in the speed of the wind (high in this demonstration) the direction of the wind, the constancy of its speed, and the shape of the swing seats. This is a complex situation and you can't wave it away by throwing out "resonance" or any other buzz-words. If this effect is not repeatable under a wide range of conditions, you should get back to basics and try to piece together some realistic dynamics that might explain it. It won't be easy, simple or clean.
 
I have little doubt that this is a wind-related phenom, though that only explains it to some extent. There is certainly something intriguing going on.

Some things to take into account:
1] in the first clip at about 0:55, a piece of litter blows across the scene, indicating the direction of wind seems to be crosswise to the swing axis.
2] the microphone seems to pick up the worst noise when the cameraman is pointed crosswise to the swing (though I don't know what that says about wind direction)
 
DaveC426913 said:
1] in the first clip at about 0:55, a piece of litter blows across the scene, indicating the direction of wind seems to be crosswise to the swing axis.

This reminds me again of the rattleback! I have a feeling, that that is counterintuitive, but still very well fully physical. The rotational motion around vertical axis, originally caused by the wind, somehow gets transformed into the swinging motion.
 
  • #10
I don't see this as being any more amazing than a sailboat.
 
  • #12
Ivan Seeking said:
I don't see this as being any more amazing than a sailboat.

Okey, my idea that rotational motion gets transformed into swinging motion was too complicated. The energy comes more probably in the same fashion as it comes to sailboats, but the rotation is still key part of this. The other swings don't get energy out of the wind similarly, because they don't rotate correctly.
 
  • #13
It's most likely a fluke. A combination of disturbances in the flow of the wind along the ground and around the other two swings or the swingset frame. It could also easily be a hoax. Grainy video quality, a lot of people standing around...it'd be very easy to just attach a piece of fishing line to the swing and pull in the same rhythm of a normally-moving swing.
 
  • #14
If you look at the dog in the first closeup (XK74) it doesn't appear to be windy from that angle. Hard to tell with everyone else bundled up.
 
  • #15
Ivan Seeking said:
I don't see this as being any more amazing than a sailboat.
If it were a lone swing, and it happened only occasionally and stopped, it wouldn't be weird. But the fact that there are two other swings immediately adjacent that clearly do not behave the same way, and the fact that it occurs quite consistently over what appears to be days or more - is odd.

Not amazing, but certainly not your textbook behaviour.
 
  • #16
DaveC426913 said:
If it were a lone swing, and it happened only occasionally and stopped, it wouldn't be weird. But the fact that there are two other swings immediately adjacent that clearly do not behave the same way, and the fact that it occurs quite consistently over what appears to be days or more - is odd.

Not amazing, but certainly not your textbook behaviour.

Also, the swing was replaced and the new one showed the same behaviour!
 
  • #17
Well, The city mayor has called a group to "Investigate" the swing, The group is called: "Vision Ovni" (UFO sight!) lol.. Anyway, this is some of the data they have collected:

They made many wind speed measurements and they say the swing moved under all this wind speeds:

11,30 hs 2.3 meters/sec
14,00 hs 2.2 meters/sec
16,50 hs 1.3 meters/sec
18,30 hs 2.2 meters/sec
20,00 hs 2.2 meters/sec

They also claim to have measured the temperature and there was no difference with it surroundings

They have measured the magnetic field while the swing was moving and when it was stopped it always was 1.2 mlg (i don't even know what that means)

Terrain galvanic current: 3 ohms


http://www.visionovni.com.ar/firmat.htm
 
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  • #18
Burnsys said:
Well, The city mayor has called a group to "Investigate" the swing, The group is called: "Vision Ovni" (UFO sight!) lol.. Anyway, this is some of the data they have collected:

They made many wind speed measurements and they say the swing moved under all this wind speeds:

11,30 hs 2.3 meters/sec
14,00 hs 2.2 meters/sec
16,50 hs 1.3 meters/sec
18,30 hs 2.2 meters/sec
20,00 hs 2.2 meters/sec

They also claim to have measured the temperature and there was no difference with it surroundings

They have measured the magnetic field while the swing was moving and when it was stopped it always was 1.2 mlg (i don't even know what that means)

Terrain galvanic current: 3 ohms


http://www.visionovni.com.ar/firmat.htm

They measured the temp? (rolls eyes). Sounds like they're looking for poltergiests.

Me, I'd be happy with one test: put up a large wind barrier upwind. If that doesn't stop it in its tracks, I will become very interested.
 
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  • #19
DaveC426913 said:
They measured the temp? (rolls eyes). Sounds like they're looking for poltergiests.

Me, I'd be happy with one test: put up a large wind barrier upwind. If that doesn't stop it in its tracks, I will become very interested.

Well, they actually claim to have done that! and the swing didn't stop

But came on, they are an ufo group, and no video for that situation.

here's the pic: http://www.visionovni.com.ar/firmath8.JPG
 
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  • #20
What happens if the swing's shape is changed, by binding it together?

This can't be debunked by watching a video. Experiments need to be performed. You can't perform the kind of experiments needed to analyze this on a video.
 
  • #21
Hi everyone, I saw this topic and decided I had to register so I could offer my idea.

Here's the thing, the swing is basically two pendulums connected together. If you know how a pendulum works then you know that the longer a pendulum is the more time it takes to swing back and forth. You can't tell from looking at the videos, but one of the chains on that swing must be slightly longer than the other one, and the result is that the swing twists at the end of each swing because the shorter chain tries to swing back before the longer chain does. Each twist turns the seat to an angle to the wind and then it catches the wind like a sail. The other swings on the set all have chains of equal length so they don't twist and hence don't catch the wind.
 
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  • #22
Very good! Thanks Mazer, and welcome to PF.
 
  • #23
Mazer said:
Hi everyone, I saw this topic and decided I had to register so I could offer my idea.

Here's the thing, the swing is basically two pendulums connected together. If you know how a pendulum works then you know that the longer a pendulum is the more time it takes to swing back and forth. You can't tell from looking at the videos, but one of the chains on that swing must be slightly longer than the other one, and the result is that the swing twists at the end of each swing because the shorter chain tries to swing back before the longer chain does. Each twist turns the seat to an angle to the wind and then it catches the wind like a sail. The other swings on the set all have chains of equal length so they don't twist and hence don't catch the wind.
That is an intriguing proposal.
 
  • #24
I think Mazer is basically right. A textbook way to get aerodynamic instability is to have an object with two vibration modes with similar frequencies and different mode shapes (usually, translation and rotation). To visualise how it works, imagine rowing a boat without lifting the oars out of the water, but feathering the blades when making a stroke in one direction. The motion is equivalent to a sine wave of translation and a sine wave of rotation of the oar, 90 degrees out of phase with each other. The basic principle is the same for the string, but it works in reverse, i.e. the fluid is doing work on the swing.

I only watched the first video link. After the guy stopped the swing, intially all the swings were moving randomly by about the same amount. If two of them had a damping factor of +0.01% (mechanical + aerodynamic) and the middle one a damping factor of -0.01%, that's all it would take.

I don't see this as any different in principle from the Tacoma Narrows bridge - or early flight tests on the Boeing 747, which seemed to want to fly by flapping its wings instead of using engine power, till they tweaked the design!

I used to work in an office with air conditioning vents on window sills and vertical strip blinds on the windows. The strip were freely pivoted at the top, and the strips were connected by a loose chain to open and close them so they could rotate fairly independently. At the bottom they were connected by a loose metal chain which notionally provided enough weight to stop them being blown around by the draft from the aircon. There were a few windows where a similar effect to the swings happened. A few strips of blind went into a finite amplitude oscillation cycle that was pretty much impossible to stop, while the rest of the blinds just moved around a bit at random. But since one of the things we did was worry about aerodynamic instability of various bits of jet engines, nobody in the office found this at all surprising.

If all the swings wanted to blow around, a couple of 10 lb weights on the seats of the other two swings would stop them, and woudn't show in video #1 (I didn't watch the other two videos).
 
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  • #25
Haunted swing..?

Read and look at this, the article claims EM force and wind is to be ruled out (which I do not see why immediatelly): http://www.thesun.co.uk/sol/homepage/news/article385529.ece

It looks much like wind effect to me.

Anybody with real explanation?

Edit by Ivan: Post merged with current thread.
 
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  • #26
sneez said:
Read and look at this, the article claims EM force and wind is to be ruled out (which I do not see why immediatelly): http://www.thesun.co.uk/sol/homepage/news/article385529.ece

It looks much like wind effect to me.

Anybody with real explanation?

Edit by Ivan: Post merged with current thread.

Wow! we went international!

That article says: "Academics" have now ruled out magnetic and electrical fields, and winds – and called in ghosthunters.

Don't be fooled by the article, there were no scientist investigating this, just an "UFO Group"
 
  • #27
Nowhere did I see anything about UFOs mentioned. Do you always just makeup stuff and then quote it?

Misinformation is a violation of the posting guidelines.
 
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  • #28
Ivan Seeking said:
Nowhere did I see anything about UFOs mentioned.
Misinformation is a violation of the posting guidelines.

Sorry ivan, but could you please show me a quote a link or whatever shows that this case was investigated by scientists as the sun article says?

I live here in Argentina and the 2 only Investigations where done by:

Jorge Bustamante, "Member of the Argentinian university of Parapsychology and Alternative therapies"
http://www.infobae.com/contenidos/340963-100884-0-Revelaron-el-misterio-las-hamacas-embrujadas

And
Vision Ovni (Translated: UFO Sight)
http://www.visionovni.com.ar/firmat.htm
http://www.lacapital.com.ar/2007/09/19/region/noticia_417455.shtml
( Así lo asegura un informe técnico sobre la investigación que desarrolló el grupo Visión Ovni. El trabajo no dice que el caso se origine por causas sobrenaturales o paranormales )

Have you read post #17? i have posted a link to the investigation a long time ago!

I you find an investigation made by real scientists please tell me..

Do you always just makeup stuff and then quote it?
I still don't understand what are you talking about. What did i made up and then quoted?
 
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  • #29
Burnsys said:
Sorry ivan, but could you please show me a quote a link or whatever shows that this case was investigated by scientists as the sun article says?

I'm not defending the article, but I take issue with quotes that come from nowhere. I still haven't seen anything mentioned about UFO investigators, except by you. What's more, many UFO investigators are scientists.
 
  • #30
Ivan Seeking said:
I'm not defending the article, but I take issue with quotes that come from nowhere. I still haven't seen anything mentioned about UFO investigators,
I think we have a language problem..http://translate.google.com/translate?hl=en&sl=es&u=http://noticiasdesantafe.derf.com.ar/despachos.asp%3Fcod_des%3D56100%26ID_Seccion%3D92&sa=X&oi=translate&resnum=9&ct=result&prev=/search%3Fq%3Dfirmat%2Bvision%2Bovni%26start%3D10%26hl%3Den%26lr%3Dlang_en%257Clang_es%26safe%3Doff%26sa%3DN
The report issued by Vision UFO arrived in the hands of Mayor Carlos Torres, "there is no basic element from electromagnetism, galvanic current, wind forces, currents isotérmicas, causing the movement of hammocks in question."

http://translate.google.com/translate?hl=en&sl=es&u=http://www.ellitoral.com/index.php/id_um/24765/origen/ranking&sa=X&oi=translate&resnum=10&ct=result&prev=/search%3Fq%3Dfirmat%2Bvision%2Bovni%26hl%3Den%26lr%3Dlang_en%257Clang_es%26safe%3Doff%26sa%3DG
There is no basic element from electromagnetism, galvanic current, wind forces, currents isotérmicas, causing the movement of hammocks in question." This concludes the report by the group Vision UFO that was delivered yesterday to Mayor Carlos Torres, who authorized the tasks to be carried forward.

http://translate.google.com/translate?hl=en&sl=es&u=http://www.lacapital.com.ar/2007/09/19/region/noticia_417455.shtml&sa=X&oi=translate&resnum=7&ct=result&prev=/search%3Fq%3Dfirmat%2Bvision%2Bovni%26hl%3Den%26lr%3Dlang_en%257Clang_es%26safe%3Doff%26sa%3DG
http://translate.google.com/translate?hl=en&sl=es&u=http://www.infobae.com/notas/nota.php%3FIdx%3D338403%26IdxSeccion%3D0&sa=X&oi=translate&resnum=1&ct=result&prev=/search%3Fq%3Dfirmat%2Bvision%2Bovni%26start%3D30%26hl%3Den%26lr%3Dlang_en%257Clang_es%26safe%3Doff%26sa%3DN
Ivan, i am not making up things, this comes from Argentinian newspapers.

Edit: No one from UFO sight that conducted the investigations has any educational background.
 
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  • #31
Okay, good enough. In the future, please provide sources for any quotes when they are made. I really thought that you were just making this up.

One more note: It sounds like this group could have scientists as members. More likely they are a bunch of crackpots or the story is reported incorrectly, but "UFO researchers" certainly does not automatically translate as "non-scientists". Most of the UFO people that I know or have met personally are Ph.D. scientists.
 
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  • #32
id say its the same thing that destroyed tacome suspension bridge in 1940 by resonance, which the wind was to blame for that also.
dunno why the other 2 swings don't go though
 
  • #33
This is a great example of resonance coupling.

The swing has two periodic components, the (regular pendulum) translational component and the torsional component (rotation about the vertical axis). The wind can cause a swing to move in either mode, but no too much, but when coupled, the effect can become quite large. This is the same phenomenon that brought down the Tacoma Narrows bridge ( ).

If the wind blows through at an angle, it can turn the swing slightly. The key is the fact that as the swing turns, it can catch the cross-blowing wind like a sail, which will give it a shove in its pendular motion. If the twisting motion has the same frequency as the pendulum ( or the two are an integer ratio), then after each pendulum swing, the seat will be in the same torsional position, ready to pick up another boost from the wind. If the two are not in resonance, the wind cannot impart a push at a consistent point in the seat's swing.

Things that can mess this up, and would also distinguish the center seat from the other two, are:
> The lengths of the chains. This would alter the frequency of the pendulum.
> The equlity of the two chain lengths on any given swing (changes the torsional motion)
> The position of the center of mass of the seat. (How "U" shaped it is) This would also alter the pendulum period.
> The stiffness of the seat material. This would alter the torsional period, and also how the seat picks up the wind when oriented a particular way. It would also affect any tensional vibration of the seat (picture the seat as a droopy guitar string - this could potentially play a role in how the seat picks up the wind)

It was unfortunately impossible to determine from just the video how these attributes of the center swing differed from the other two.

I also noticed that there was a depression in the swing area which was centered around the middle swing. This alone could account for the differences in behavior: If the wind were strong enough (and it sounded like it was) air flowing at the edge of the depression would be slightly turned downward or upward, i.e. turbulent, whereas wind going across the center area would be more laminar. This would give a more steady and even air flow across the seat, and thus a more consistent push.
Someone suggested the poles might also play a role. I wouldn't think this would give a real great contribution; however if we are considering turbulence in the airflow, the poles might be just large enough to break the laminar flow of the air for only a short distance after the pole, i.e. to the first swing and not the second or third.
 
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