Natural resonance: Worse results than breaking wine glasses

This post refers to the last statement in Cecil’s post:

Here, it is basically said that some experts believe the common explanation of winds hitting the right frequency of this bridge is over simplified. But, isn’t this simply splitting hairs? The text below describes how the cables go slack making the bridge unstable. Ok, but what is the point of origin for this? Was the rbidge haunted? No, it was the wind swaying the bridge at just the right frequency, right? To me, it’s like arguing do guns actually kill, or is it really the bullets? The initial cause was the wind; the rest is purely academic, is it not?

Here is the exact text; I added the italics to catch your eye:
“Reader Wilbur Pan has alerted us to a recent report in Science News heaping abuse on this widely held view. Mathematicians Joseph McKenna and Alan Lazer doubt that a storm could produce the perfectly timed winds required. They’re working on a “non-linear” model of bridge behavior they hope will provide a better explanation. The main problem apparently is that when the roadway of a lightly constructed suspension bridge flexes, the cables supporting it go slack, introducing an element of unpredictability in which little causes (i.e., the wind) produce big results (i.e., a collapsing bridge). They hope to have the mathematical model describing this effect finished in five years–not the most aggressive schedule in the world, but apparently this is government work. You’ll read about it here first.”

Here is a web page that explains the differences among the theories as to how the bridge failed: Tacoma Narrows Bridge. The main point is that harmonic resonance is almost impossible when wind is the driving force because wind doesn’t stay at one speed. Thus, although the wind obviously caused the bridge to oscillate, it didn’t do so by blowing at a specific speed, causing harmonic resonance, causing the bridge to move.

Can’t comment on the wine glasses, but Mythbusters took on Bridge resonance. Twice. The first time, they declared it Busted. The second time: Plausible.

Video: Mythbusters - Briddge

While they busted Nicole Tesla’s claim of an earthquake machine, I recall (but couldn’t find) where they set up an audio resonator on a bridge. Didn’t knock it down, but they felt the vibrations.

Vaguely related aside: While audio waves may not break glass, they can make airplane flights better. Bose noise canceling headphones use the opposite of resonance to cancel out sound. Works pretty well. Makes riding a bus or a flight with a crying baby almost tolerable.

This is a subject that hasn’t been studies as much as it could. Cecil is on the cutting edge, as usual.

Myth Buster also showed you could break a glass with an unaltered human voice

Start at 4:30

Dude, you stopped watching too soon. Mythbusters also confirmed it’s possible to break a wine glass using the human voice.

Now, they had a professional with some serious pipes, so it may not be possible for you to break a glass with your voice, but at least some people have done so.
This thread is of course referencing the classic column re-posted on the front page today:

Regarding the recently re-published article: “Can opera singers shatter glass with their high notes?” (Originally published May 11, 1990).

Cecil mentions resonance results (some, admittedly disputed) more serious than broken stemware: A bridge that collapsed under the lock-step marching of soldiers (and they wonder if all the Chinese population jumping from chairs in unison could cause earthquakes! :stuck_out_tongue: ), and the infamous Galloping Gertie (Tacoma Narrows) bridge collapse. Cecil doesn’t mention how many, if any, casualties there were among those soldiers.

The Tacoma Narrows bridge caused only one casualty, a dog trapped in a car that fell into the water. This failed to be a human disaster because it was well known that the bridge was going to collapse like this, and it had been closed. And, in fact, there were video cameras watching for it, so we have some excellent videos of the whole event, which you can easily find on YouTube. (The car on the bridge was of a journalist, who is seen running for his life in some of the videos.)

Okay, now to my point: There actually were, in fact, seriously worse resonance disasters that DID cause substantial loss of life. Specifically, several nearly-new Lockheed Electra airplanes crashed, circa 1960 or so, due to resonance that caused the wings to flap excessively, to the point that the aircrafts just broke apart in flight. (I first read about this several years ago, in a side-bar in my Differential Equations textbook.)

Here, for example, is one article I found on this subject.

Apparently, similar potential problems were discovered during the testing of the Boeing 787 Dreamliner.

So, did Joseph McKenna and Alan Lazer ever finish their work?

To answer Timon of Dallas’ doubts about the human voice’s ability to breaking glass: Glass breaking with nothing but the unamplified human voice: Mythbusters of course.

Although video in 1940 is not technically impossible, I rather doubt it.

Okay, some hired artists sat beside the bridge, day and night for weeks, just waiting for the big splash. When the bridge starting really heaving, they got busy and drew detailed pictures (just like artists in courtrooms), only drawing many many fairly high-resolution pictures per second so a movie could be made of it. Or maybe all those [del]videos[/del] [del]drawings[/del] silver halide images of the event, as seen on YouTube, are just modern re-dramatizations. Or maybe, if video in 1940 is not technically impossible, somebody really made a video. Or maybe I just used the wrong word for “movie”. Or maybe it was all just a hoax that never really happened.

Or are you really doubting that there are pics of the above-mentioned incident on YouTube?

Just go take a look in the Pit to see if I’m there.


Just FYI, I merged three threads on the same subject into one. So if the answers don’t quite flow the way they should, you know why. Should not be a problem, though.



Silver-halide images are not videos. While we’re at it, vinyl LPs are not CDs, adding machines are not computers, Ben-Hur didn’t drive an Indy car, and lintels are not arches.

Pedantry is not necessary.

Neither is illiteracy.

Well, if you’re going to be ad-hominem, I’ll just point out that your pedantry is simplistic to the point of error.

[li]Well before the advent of consumer electromagnetic recording/playback devices, “video” was used for “silver-halide” imaging. For instance, even in my middle school days, it was called “audio-video club”. And that was back when electricity was a novelty. :p[/li]
[li]Related to 1 above, according to the OED, “video” dates back to 1937 at least. Since television technology was then only in its infancy and electromagnetic video recording not yet invented (not until 1951-1952), it’s obvious that “video” wasn’t restricted to the idea of “video tape”. [/li]
[li]Regardless of whatever imaging technology was used in the original recording of the 1940 event, I can assure you that anything you may see now will be “video” in every pedantic hyperliteral sense of the word.[/li][/ol]

In other words, you don’t get to be pedantic unless you are first correct.


[li]I don’t much care about misunderstandings you had when you were twelve years old.[/li]
[li]What the Oxford English Dictionary actually says is that video means “that which is displayed or to be displayed on a television screen or other cathode-ray tube; the signal corresponding to this.” The specific quote given for 1937 is “Video, the sight channel in television, as opposed to audio, the sound channel.” And I never mentioned video tape at all.[/li]
[li]And it is bootless to claim that a Youtube copy of the 1940 footage is video now. The original reference was to “video cameras”.[/li]

John, please drop this. It makes you look like an ass.
Powers &8^]

Since when has being right been a crime?

Since when has it been perfectly OK to use ambiguous language in order to seem to be saying, “The Oxford English Dictionary agrees with me,” when it does not.

The original poster said that the Tacoma Narrows Bridge was monitored by video cameras in 1940. I said it wasn’t. Since then, I have been bombarded with half-truths, nonsense, and now direct insults for the great offense of telling the truth.

I didn’t say you had committed a crime; I said your unnecessary pedantry is making you look like an ass. It’s one thing to mention it; it’s another thing entirely to harp on it as if it had anything important to do with anyone’s point.
Powers &8^]

I’m not “harping on it”. I am responding, one at a time, to foolish, wrong, and sometimes downright dishonest attempts to make someone else’s mistake somehow or other my fault. Quit dogpiling on me, and I’ll quit complaining about being dogpiled on.