Tuesday, August 7, 2018

Maurice Cotterell manages to be even more wrong

        I didn't think my jaw could drop any further than it did back in January 2017, in disbelief that Maurice Cotterell could be invited onto a popular overnight radio show to explain a mathematical idea that was so totally wrong that it "made one gasp and stretch one's eyes" (to misappropriate Hillaire Belloc's very inventive expressionnote 1).

        And yet, here he was, last Sunday night on Coast to Coast AM, going one better. Just like last time, he was only summarizing what is on his web site so you can get the whole thing without having to slog through two hours of audio.

        He seeks to explain why so many Mars landers have crashed instead of soft-landing as intended (10 out of 18, according to him, and for all I know it may be the correct figure). Here are the steps in what he laughingly calls his "logic":
  1. The gravitational attraction a planet has for an object in its vicinity is only partly described by the Newtonian force G.m1.m2/d2
  2. There's an additional term to consider, the centrifugal force generated by the planet's rotation.
  3. This force acts in opposition to the Newtonian force.
  4. Since Mars' rotation rate is 2.5% slower than that of Earth (actually the firgure is 2.8%) it generates less centrifugal force, and therefore more effective gravity, in its vicinity than Earth.
  5. An incoming lander is subject to the sum of the forces of gravity and centrifugal.
  6. Therefore a terminal flight profile calculated to be correct in Earth conditions fails on Mars.

Is he right? No, of course he isn't
        Well, first off let me say that centrifugal force acting in opposition to the force of gravity on the surface of a planet is, indeed, a reality. "It's a thing," in the slang of today. This force can readily be calculated; it is

-(mvcos L)/r 

where m is the mass of an object on the surface of a rotating planet
v is the linear velocity of the planetary surface at the equator (465 m/sec for Earth)
r is the radius of the planet (6.378 x 106 m for Earth)
L is the latitude where the force is measured

        For Earth, the (v2 cos L)/r  term works out as 0.034 m/sec2 at the equator where cos L evaluates to 1. A body, such as a fat woman, of mass 100kg weighs 340 grams less at the equator than at the poles, where cos L, and the centrifugal force, are both zero.note 2

        Statements 1 & 2 are therefore in general correct when considering an object on a planet's surface. Statement 3 is also correct—it's perfectly possible to imagine a planet that rotates so rapidly that anything not tied down at its equator would be flung off into space. We would say that centrifugal force exceeds the force of gravity, in such a case.note 3

        Statement 4 is a problem although Cotterell is basically correct in writing that centrifugal force is less on Mars. It has as much to do with the smaller size of the planet as with its rotation rate. However, that small difference is swamped by the fact that Newtonian gravity is very much less. Here are the figures (at the equator in both cases):

        Earth, acceleration due to gravity: 9.863 m/sec2
        Earth, acceleration due to centrifugal force: -0.034 m/sec2
        Net acceleration: 9.829 m/sec2

        Mars, acceleration due to gravity: 3.721 m/sec2
        Mars, acceleration due to centrifugal force: -0.0171 m/sec2
        Net acceleration: 3.704 m/sec2

         It's in writing Statement 5 that Cotterell has gone completely haywire. He writes "Newton failed to recognize, in his equation, that a falling body is also under the influence of 'centrifugal force' caused by the spinning of the Earth on its axis." He's taken the purely local and surface-based phenomenon of centrifugal force, and made it a property of the planet as a whole, extending beyond the surface into the region where incoming landers start feeling the effect of a planet's gravity. This is as preposterous as Cotterell's prior comments about gravity, and shows complete lack of understanding of physics. Of course a spacecraft having no physical contact with a planet cannot possibly be influenced by rotation of the planet. Neither can a falling apple, come to that, so Newton's equation describes that event accurately.note 4

        Statement 6 suggests that engineers devising flight profiles for soft landings simply don't know about this, and therefore miscalculate. Last Sunday night, even that old softie George Noory demurred in the gentlest possible way. He reminded Cotterell that the landing of MSL and its rover Curiosity in Gale crater six years ago (almost to the day, actually) had been a brilliant success and by no means a miscalculation. Cotterell mumbled something about engineers having learnt that when they completed their calculations they should "add a little bit, just for luck."

        Cotterell is kind-of entertaining I suppose, with his bluff manner and his soft Lancashire accent, but he should be permanently banned from the fields of physics and mathematics lest he do even more damage to them.

=================/ \=====================
[1] "Matilda told such dreadful lies"

[2] In fact, there's another phenomenon that affects the acceleration due to gravity on the planet's surface. The equatorial radius is 6378 km but the polar radius is only 6357 km. Since the fat woman is 21 km further away from the center of the planet when she's on the equator than when she's at the poles, gravity has less of a hold on her. The effect amounts to 0.668%.

[3] I'm going to be in trouble with the purists for even talking in terms of "centrifugal force." To them, this force is merely the "equal and opposite" reaction to a centripetal force. They would prefer to say "The force of gravity is inadequate to provide the centripetal force needed to keep objects attached to the planet." See the difference? But Cotterell uses centrifugal, and it's intuitive, so I'm going to stick with it.

[4] Note that as long as the apple is attached to the tree, it is pulled upwards by the small amount attributable to centrifugal force. As soon as it detaches, however, that small upward force vanishes.

Thursday, August 2, 2018

Robert Morningstar: FAIL!!

James Concannon writes...

        In my opinion, Robert Morningstar has just suffered the most humiliating failure of his career. The closest approach by Mars for 15 years has come and gone without any of the disaster effect AM* predicted. On Facebook, Morningstar is now dodging and weaving, making up excuse after excuse, but it's pretty much an open-and-shut case. This was his word-for-word prediction, on FB 17th July:
"Mars' passage close to Earth on July 31st, 2018 will created [sic] super storms like Katrina (again, as it did i 2003), along with volcanic activity and intense electrical storms around the globe. Be ready for something and anything."
        Let's take this piece by piece. I'm allowing one day either side of his prediction, to be generous, so I'll be reporting activity for the three days 30th July—1st August.


        The closest thing to a superstorm in the last week was typhoon Jongdari, which caused havoc in Japan on 29th. Hilariously, just as the "Mars effect" hit us on 30th, Jongdari was downgraded to a tropical storm. There were torrential rains in Myanmar but, y'know, it's monsoon season so there's nothing unusual about that.

        Grasping at what straws were in the wind, Morningstar cited what he called "devastation" in Mexico. What a joke. The weather system he spotted was a depression which eventually became tropical storm Hector. Wind speeds were reported as a mere  35 knots, gusting to 45. No reports of any damage, loss of life or even injury.

        When I pointed this out, Morningstar replied "I think a crashed airliner is devastating enough. N'est as, Dumas?" OHH... OHHH.... a crashed airliner, oh yes how silly of me. At 3:45 pm on July 31st, Aeroméxico Connect Flight 2431 crashed almost immediately after take-off from Durango International Airport. A hailstorm was in progress, and the Embraer twin-jet with 103 aboard was probably the victim of a down-draft. All 103 people walked away, although there were 85 injuries.

        Is Morningstar seriously expecting us to equate this incident with Hurricane Katrina, a Category 5 hurricane that caused catastrophic damage from central Florida to eastern Texas in August 2005? The cities of Gulfport MS and New Orleans LA were substantially destroyed, and 1,245 people died from the immediate impact and subsequent flooding. Wind speed of 280 km/h was recorded. So don't give me crashed small airliners with no fatalities, although the incident was no doubt devastating to those involved.

Volcanic activity
None, other than ongoing sequences such as the eruption of Kilauea, which began 30th April.

        Again wriggling, Morningstar cited the 27th July evacuation of Ambae island due to the imminent eruption of the Manaro Voui volcano. In fact, the island had been evacuated already, starting in September 2017 when volcanic activity increased to Level 4, and reinforced in April this year. The island is coated with a deep layer of ash but there are no reports of death or injury. So even if this eruption had happened during the three days of the Mars effect, it would have been pretty unimpressive.

        Morningstar's prediction did not specifically mention earthquakes, but under the general heading "something and anything..." the three days of the "Mars effect" were free of any major seisms anywhere on the globe. The closest was a 6.4 magnitude earthquake at Lombok, Inodnesia that killed 14. That was on the 29th so it doesn't count.

Intense electrical storms around the globe
        This one is interesting. The lightning maps maintained by Blitzortung.org showed that Europe had been unusually sparky during the week prior to Morningstar's predicted effect.

Lightning, Europe, 28th July

By the 31st, Europe had calmed down somewhat

Lightning, Europe, 31st July

As for "across the globe", that one was a busted prediction without doubt. Here's North America and the Caribbean:

Lightning, North America, 31st July

...and as for the Southern hemisphere, calm prevailed:

Lightning, Oceania/Australasia 31st July

         These maps all show the lightning strikes accumulated from noon to 2pm local time on the dates indicated.

Morningstar pleads for more time
        Morningstar got so interested in this topic that he sat down and wrote a pseudo-scientific essay, The Mars Effect: How Mars’ Close Passage Exerts Geo-Magneto-Electric Effects Inducing Electrical Forces in the Earth’s Core.  Here are some excerpts from this woefully ill-informed work, which muddies the waters by conflating the Mars approach and the Lunar eclipse of 27th July:
During an eclipse, whether solar or lunar, there will be a summation of G Forces when in concert (i.e. in the same direction during solar eclipse),  or  as opposing G Forces during lunar eclipses).
When in that celestial configuration, there will be a differential subtraction of gravitational forces, whose buildup and break-down phases will compound the G-stresses on the Earth’s core and the Earth’s mantle as the 2 gravitational forces,
However, in this unique case of July 29th, 2018, with Mars involved, there were  3 sets of contending G-forces, tangling and tugging on each other like rubber bands from different angles at every passing moment as Sun, Earth, Moon transited in lunar eclipse, as Mars raced toward the Earth-Moon system with astronomical speed, interacting with gravitational forces and geo-magnetically with Sun, Earth and Moon during lunar eclipse:
The magnetic fields of all these celestial bodies were forced toward each other, pushing pressing, intersecting, overlapping, and thereby, inducing electrical activity between them and amongst them.
Finally, the Disentanglement Phase of the G Bands, where Mars is concerned, may take weeks to unwind, and so The Mars Effects on Earth’s weather, its plate tectonics and volcanic activities could take several weeks to dissipate, but during this critical phase a new series of super storm could be spawned by The Mars Effect like Mars did in 2003, spawning the super hurricanes, Katrina, Rita and Ophelia, which I announced and predicted on July 5th, 2003 while speaking as guest n the Jonathan P. Casey Radio Show, broadcast in New Jersey and the Philadelphia area.
        Morningstar seems incapable of understanding that the Sun/Earth/Moon alignment happens every single month, at New Moon and Full Moon. In gravitational terms, there's nothing special about an eclipse. He also seems unaware that Mars has no magnetic field, and he has the date of hurricane Katrina wrong. When I asked him, on Facebook, what his source was for the information that the Mars effect would now drag on for three more weeks, his hilarious reply was «I am "The Source."»

The mathematics
        I must admit I got a surprise when I calculated the actual gravitational interaction between Earth and Mars. The answer is, with Mars in conjunction, 2.409 x 1016 newtons. With Mars at opposition, its closest approach, 8.76 x 1016 newtons, or 3.64 times as much. Even though a newton is a rather small force (roughly 4.5 to the pound) that's more than I expected. Note that the accelerations produced are 0.403 x 10-8 and 1.47 x 10-8 respectively—very, very small numbers).

        The gravitational attraction of the Sun is 40,000 times stronger and that from the Moon 200 times stronger. Dreamers like Morningstar should contemplate such data before they go making silly predictions.

        Let there be no doubt about it—regardless of how Mr. Morningstar now spins the data, this one was a total bust.

Update 14th August:
       Hector developed into a category 4 hurricane, and was thought at one time to be a threat to Hawai'i. It holds the record for most time (186 hours) as a cat 4 in the NE Pacific. However, it missed all the islands to the South and rapidly weakened. As of today it's been downgraded to a tropical storm. If Hector had ever become cat 5, and especially if it had done significant damage in Hawai'i, Morningstar would have been jumping up and down yelling about what a brilliant prognosticator he is. As things stand, his talents are seen to be crap.