Full of Hot Error

Once again, it's time for a round of corrections to past Skeptoid episodes. These episodes are fun; many listeners either love them or hate them. They're not a new single subject, but instead they go back and revisit a half dozen or so previous episodes to either correct an error or provide some newer information that may impact the conclusion. I always really enjoy these, not just because we get to revisit previous subjects that I've come to love, but also because they improve each episode with better, newer, or corrected information. In that way, these episodes are the heart of what Skeptoid is. When we learn something new, we adapt our understanding of a subject to accommodate the new information. So let's get started.

The Betz Mystery Sphere

Episode #334 was about a famous urban legend concerning a mysterious metal ball known as the Betz Mystery Sphere. It was a 10kg, 20cm hollow steel ball claimed to have all sorts of strange powers — powers which, sadly, failed to be replicated under controlled conditions. It was ultimately identified by a sculptor who had lost it (along with several others) about where the Betz family found it. It had been given to him by a friend who worked at a company that employed a number of great big industrial valves, which I described in the episode as ball valves. Listener David wrote:

I found your article from 2012 on the Betz Sphere, and found it interesting reading. There are some anomalies in the explanation presented that do not add up though. I am very familiar with ball valves of both the floating and trunnion type. All ball valve balls are largely a hole. They are never solid balls otherwise how would they ever open. Their principle of operation requires that they rotate on an axis and align a large central hole with a port either side which permits flow. They turn off by being rotated to right angles thus closing off the hole. They also possess a shaft or hole with an axis at right angles to be able to drive the rotation. So, part of a ball valve it is not, and likely never was.

David is correct, the Betz sphere — missing a large hole through its center — was definitely not part of a ball valve. This was my bad for not better fact checking the published accounts of the sculptor's description. It was from a ball check valve, a very different piece of equipment. In a ball check valve, a ball falls (or is pushed with a spring) against an opening to close it off and prevent fluid from entering that opening, while allowing fluid to come the other direction by pushing the ball out of the way. The episode transcript has been updated to reflect the correct type of valve.

The Sound Barrier, the Bell X-1, and the B-29

Episode #154 was one of my personal favorites; it looked into the claims of various pilots who apparently broke the sound barrier before Chuck Yeager did it in the Bell X-1 in 1947. This included one case where pilot George Welch, flying an XP-86 jet fighter prototype, buzzed the bomber carrying the X-1, rattling it with a sonic boom — according to some accounts. This raised an unexpected question: was the bomber carrying the X-1 a B-29 or a B-50? I had a fair number of emails from aviation fans arguing for both types. In my original episode I called it a B-50, as given in the reference material I used for the events of that day.

I finally put this question out to the Skeptoid research email list, and again got conflicting accounts. The confusion stems from the fact that the B-29 and B-50 are nearly identical. The B-50 was a later variant, re-powered with bigger engines and a few other improvements; at a glance, you probably wouldn't see any difference. You'd think it would be simple to look up which was used, but the problem is that the X-1 program used both types. In some photos, a B-29 is seen; in others, it's a B-50. Even articles on both the NASA and USAF websites give conflicting accounts.

Finally an authoritative source was found: the radio transcript of Yeager's flight on that day, on file today at the National Air & Space Museum. The radio conversation included the tower, Yeager, the bomber pilot and flight engineer, and two chase pilots. The bomber is referred to by tail number, "eight-zero-zero", and occasionally as "B-29 eight-zero-zero". So, mystery solved, with no room for error. It was B-29 tail number 512800, easily discoverable in many photos of the program. The episode transcript has been corrected.

Trade Winds, Westerlies, and the Ellen Austin

In episode #699, about the nautical mystery surrounding the 19th-century ship the Ellen Austin, we discussed sailing routes across the Atlantic. Ships going from England to New York would cross the North Atlantic, fighting headwinds the whole way, which I called the trade winds. Then listener Olaf wrote in:

Taking the northern route, the ships would have to fight the westerlies. Taking a route at least 2000 miles south of it (my guess), on the other hand, they could take advantage of the trade winds.

Woe be unto the science podcaster who relies upon his own general knowledge without fact checking everything. I had always thought that all the oceans' prevailing winds were called the trade winds. Not so! That term is reserved for the east-to-west winds circling the equator; while the winds I was referring to — the west-to-east winds fought by the Ellen Austin across the North Atlantic — are called the westerlies, just like their southern hemisphere counterparts. Thank you, Olaf, and the transcript has noted the correction.

Alkaline Water and Bleach

Episode #654 was a pop quiz about consumer ripoffs, and one of the questions concerned the alkaline water machines sold as miracle health cures through multilevel marketing programs. We noted that chemically, all they really accomplish is the same thing as if you were to add a tiny bit of "something" to your water, and three choices were offered, two of which were bleach and baking soda. The correct one, I said, was bleach. But then listener Lisa got that answer wrong and wrote in:

Having at one time been almost seduced by the promised benefits of alkaline water, I had done some research that indicated that adding baking soda creates home-made alkaline water. So I was shocked when I got that answer wrong (your answer was bleach). Here's some information that suggests that baking soda is indeed the correct answer. Thanks for your time and consideration.

And lo, she was absolutely right. Both baking soda and bleach will make your water alkaline if you add a bit. So it was my quiz that was wrong, as it offered two correct answers. I've since fixed it up, and replaced baking soda with another option, that I hope still might fool you. Apologies to any alternative health believers who stopped adding baking soda to their water as a result of my quiz, and switched to bleach instead.

Maelstroms: Centrifugal vs. Centripetal

OK this next one really caused some folks to go batty over here. Episode #382 was about the old tales of the Maelström, the legendary whirlpool in Norway said to swallow ships whole. At one point during the discussion of the physics involved in a whirlpool, I mentioned centripetal force as the force pushing the water out away from the center of the whirlpool. I'm sure you can guess: this followed a lengthy debate about the difference between centripetal and centrifugal. A number of people on the Skeptoid research mailing list weighed in, and though most of them were probably right, I managed to come away both confused and favoring the wrong interpretation. Listener Gavin rightly called me out on it:

...I noticed in one paragraph you said "Centripetal force pushes the water away from the center of the whirlpool... But deeper, as water pressure counteracts the centripetal force,..." I think you meant to say "centrifugal force" (or more properly, the centrifugal effect, as it is not a real force but an artifact of a rotating frame of reference) rather than "centripetal force". Centripetal force is whatever (real) force is keeping the centrifuged objects or material from flying off on a tangent to infinity, in this case the pressure of the surrounding water as mentioned in the article. This error is repeated a few paragraphs later when discussing hazard to boats, where you write "Water has so much mass that the gravity easily overcomes any centripetal force in a large maelstrom." Your description of the physics involved is otherwise accurate, and you seem to have a good understanding of physics and science in general based on your other articles, so I'm guessing you just mixed up the words.

Gavin was being a little generous, because while I did mix up the words, I also didn't put in the work to really understand the difference. But a lot of people don't understand the difference. Gavin explained it accurately, but here's another analogy that may make it clearer.

Imagine a race car going around an oval track. The car's inertia wants it to go straight. But when the driver gets to the corner, he turns the wheel, and the mechanical grip of the tires on the track surface pushes the race car in toward the center of the track. That's an actual force being applied against the car, and that's centripetal force. Centripetal has a "P" in it, for "push", an actual pushing force toward the center. It could also be a "P" for "pull" if it was, say, one of those carnival rides that spins around with everyone going around on swings, and the chains are pulling the riders toward the center rather than letting them go straight. Whether it's a push or a pull, centripetal — with a P — is the lateral force toward the center, preventing you from going straight.

The driver of the race car, though, feels himself getting squished against the inside of the car, and we tend to call this centrifugal force. That's not quite accurate, as the only force acting on him is the wall of the car pushing against him to keep him from going straight — the same centripetal push that the tires are doing to the car. It's more accurate to refer to the driver's squished feeling as an apparent force, as it's not an actual force. Think again of the carnival ride: the post in the center feels all those chains being pulled away from it. The outward pull is the apparent centrifugal force; the only actual force in effect is the centripetal pull of the chains on the riders. The post feels all those riders trying to flee away from the center — and so centrifugal has an "F" for "flee".

The description of the whirlpool physics has been amended on the transcript page to correctly use these terms.

Please, listeners, keep those corrections coming. Submit yours at skeptoid.com/corrections, and there's a link to this at the bottom of every episode transcript. Remember, science is the process of continually refining and improving our theories with new information, and that applies to Skeptoid episodes too.

By Brian Dunning
Follow @BrianDunning