A new invasive seagrass has been spotted off the waters of South Florida and scientists are working to see what danger it could pose for native seagrass and the plants, fish and marine animals they support.
The seagrass, called Halophila stipulacea, was discovered in a marina on Key Biscayne in Biscayne Bay. This is the first time it has been identified off the coast of the continental United States. The non-native species could be a threat, depending on whether or not the newcomer will compete with and displace our native seagrass species, said Justin Campbell, Florida International University marine scientist.
The invasive seagrass came from around the Red Sea and the Suez Canal area and is native to the Western Indian Ocean, Campbell said. It crossed the ocean, probably as part of boat passage from the Mediterranean, he said. It showed up in the Caribbean on the island of Granada around 2002. By 2017, it had spread to the Virgin Islands and Puerto Rico. “And then now, very recently, it has showed up on our doorstep here in Florida,” Campbell said.
The invasive species doesn’t look like our native seagrass, which has long leaves and tall, grass-like canopies. The invasive species has short, tiny leaves, he said. Scientists believe it has been spreading through a process of fragmentation or asexual reproduction. The species fragments very easily, meaning that small pieces can break off, Campbell said. “Those small fragments have the capacity to float for a week, ten days, and then potentially resettle in a new area and start growing again.” It’s essentially a clone of the parent fragment, he said.
“It’s really hard to predict what the consequences of this is going to be,” said James Fourqurean, a co-author of the research paper and director of the Coastlines and Oceans Division in FIU’s Institute of Environment. “This is a species that can spread incredibly rapidly. The meadows that were just discovered this summer (in the bay) are too large to have grown in a single year. So we know that it’s been here for multiple years already,” he said. The invasive seagrass will eventually spread even to the Gulf of Mexico, though not directly from Biscayne Bay, he said. “There’s no biological reason that it won’t grow all around the Gulf of Mexico,” he said. “It’ll get there. It’s just a matter of time.”
Noted.
Related:
“Recent Immigration Surge Has Been Largest in U.S. History” (New York Times, Dec 11, 2024): Under President Biden, more than two million immigrants per year have entered, government data shows. The immigration surge of the past few years has been the largest in U.S. history, surpassing the great immigration boom of the late 1800s and early 1900s, according to a New York Times analysis of government data. Annual net migration — the number of people coming to the country minus the number leaving — averaged 2.4 million people from 2021 to 2023, according to the Congressional Budget Office. Total net migration during the Biden administration is likely to exceed eight million people. [There’s a chart showing that 190,000 net immigrants/year arrived in the 1850s compared to more than 2 million/year during Biden-Harris, but the bars are as a percentage of population so it doesn’t look like 10X the rate.]
We recently had to toss a pair of Wusthof shears that had gone ridiculously dull. I tried sharpening them with a simple honing steel and it didn’t help. The typical commercial sharpening service won’t handle scissors. I don’t have a sharpening stone. (Maybe some of you all know whether it is practical to sharpen shears like the above? If so, what’s the technique and equipment required?) Despite the fancy German brand name, I think that these were #FakeWusthof made-in-China and cheap ($25 on the Web right now).
I discovered via some Amazon order research that our still-sharp Shun shears celebrated their 9th anniversary of domestic abuse (put in dishwasher for sterilization after cutting meat, for example). They’ve never been sharpened and are still highly effective. The screwdriver blades on the back of the handles are a fun idea, but we have never used them.
I’m not sure if there is a reasonable option for America First enthusiasts. Is there any U.S. company that can compete with the Japanese, Swiss (Kuhn Rikon), or Germans (not the fake Germans in China who made our recently tossed “Wusthof” shears) in standard knives and scissors?
the Wirecutter (NYT) absurdly purports to rate kitchen shears, doesn’t include the Shun, and says a $15 Chinese-made OXO is the best (based on a 2017 review, which when I tried to find it Google showed me the NYT/Wirecutter article “The Best Pubic Hair Trimmer”)
Update: I bought the more expensive Shun shears and they’re heavier. It’s unclear if they’re better but at least now we have a second pair to use if the first is being sterilized in the multi-hour dishwasher (thanks, regulation!).
The Yale Alumni Magazine arrived in our mailbox with a cover reminding the Righteous that Yale students were on the Right Side of History (TM) against the “other apartheid regime” (i.e., not Israel) back in the 1980s:
The article, titled “The shanties on the plaza”, never explicitly mentions the noble Palestinians nor the modern apartheid state of Israel, but the parallels are pretty obvious and I think we can all agree on who was in the right back then.
What about the Extremely Unrighteous? From December 2:
The incoming dictator threatened the entirely peaceful hostage-holding Gazans with “Those responsible will be hit harder than anybody has been hit in the long and storied History of the United States of America.” Considering what we did to Tokyo (100,000 civilians killed in one night), Hiroshima and Nagasaki, I’m not sure how this promise could be fulfilled.
Related:
“Nelson Mandela’s support for Palestinians endures with South Africa’s genocide case against Israel” (state-sponsored PBS): “We have stood with the Palestinians and we will continue to stand with our Palestinian brothers and sisters,” Mandela’s grandson, Mandla Mandela, said at a pro-Palestinian rally in Cape Town in October, days after the Hamas attack in southern Israel spurred the war on Gaza. Mandla Mandela, an ANC lawmaker, wore a black and white Palestinian keffiyeh around his neck as he spoke to a large crowd.
Today the Federal Reserve technocrats depressed investors by saying that interest rates won’t be lowered all that much in 2025 (unsaid: Congress won’t put down the deficit spending crack pipe and, thus, inflation is inevitable). Mary C. Daly, last seen addressing the diversity crisis at the San Francisco Fed and ensuring the stability and longevity of Silicon Valley Bank, voted with the rest of the governors to cut interest rates by 0.25%. The lone dissenter to the cut was from the Rust Belt: Beth M. Hammack, head of the Cleveland Fed (formerly at Goldman). Let’s follow Ms. Hammack going forward and see if she’s right about the inflation that the government and media assure us does not exist.
(A friend asked why the stock market was down today. She’s a physician and had interpreted the news from the Fed meeting as a prediction that the U.S. economy was going into a slump. My response: “Fed said it would have to keep interest rates high. Congress wont stop deficit spending. So the only way to tame inflation is high rates, which means stocks need high yields to compete w bonds. If a stock pays a fixed dividend it can only generate a higher yield by falling in price. Remember if you can buy a bond yielding 6% you need to buy a stock at a price where you’re sure you’ll get at least 8% return.” Curiously, the Wall Street Journal had a headline about the Dow Industrials (below) rather than the S&P 500.)
Speaking of non-existent inflation, I went to a museum today in Colorado Springs. It is inside a massive 1903 courthouse that is three stories high with a clock tower reaching skyward beyond. The volunteer at the front desk told me that it cost $420,000 to build.
It was replaced in the 1970s by a monster-sized concrete “judicial center” across the street:
What was inside the museum? An art exhibition in which paintings from any artist with a connection to the region were welcome… so long as the artist identified as “female”:
A reminder that SARS-CoV-2 was not the first pathogen to realize what fat targets humans living in cities presented…. (Colorado Springs was a cure destination for tuberculosis sufferers.)
The glorious history of test equipment… (HP had a division here making oscilloscopes, spun off and spun off and now “Keysight”)
It seems as though taxpayers got a good return on their $420,000 investment.
Kwanzaa will be here soon. I can’t find a sizable toaster plush toy for family use in celebrating the holiday by hitting each other over the head, Maulana Ndabezitha Karenga-style (“born Ronald McKinley Everett”).
Two years ago, ChatGPT was confident that Mr. Karenga was not a convicted criminal. From Toaster for Kwanzaa, in response to “Is the founder of Kwanzaa a convicted criminal?”
The founder of Kwanzaa is Maulana Karenga, who is not a convicted criminal.
In 1971, he was convicted of felony assault, torture, and false imprisonment of women.
The story is more nuanced today. Given the same prompt, ChatGPT admits that Karenga was “convicted of assault charges” (no mention of torture or women, both of which could be considered prejudicial) and it is careful to point out some of the great works that Mr. Karenga has accomplished since being released from Club Cali:
Dr. Maulana Karenga, the founder of Kwanzaa, is a prominent scholar and activist who created the holiday in 1966 as a way to celebrate African heritage, culture, and community. However, in the early 1970s, Karenga was convicted of assault charges and served time in prison. The details of the case remain controversial, and Karenga has consistently denied the allegations.
Since then, Karenga has continued his academic career and activism, earning a Ph.D. and serving as a professor of Africana Studies. His work on Kwanzaa and other cultural and social initiatives has significantly influenced African American cultural expression and community-building efforts.
I followed up with “did the founder of Kwanzaa hit women over the head with toasters?” and received some more detail on Mr. Karenga’s crimes, but also that he has denied them and some more about the great work the man has done.
Dr. Maulana Karenga, the founder of Kwanzaa, was convicted in 1971 on charges of assault and false imprisonment involving two women. Court records and reports from that time contain allegations that the women were tortured, including claims that they were burned and beaten. One of the allegations stated that a toaster was used as a weapon during the incidents. Karenga has denied these allegations.
It’s important to note that this chapter of his life is controversial and often discussed in the context of his later academic and cultural work. Karenga went on to complete his Ph.D., become a university professor, and focus on promoting African cultural heritage, including through the creation of Kwanzaa. The holiday itself has grown into an internationally recognized celebration of African American culture and unity.
What if we were to ask about Donald Trump? Would ChatGPT similarly be careful to mention that Trump has denied any criminal wrongdoing or find an “important note” about positive things that Trump has done? Here’s the response to “is donald trump a convicted criminal?”:
Yes, Donald Trump is a convicted criminal. On May 30, 2024, a New York jury found him guilty on all 34 felony counts of falsifying business records. These charges were related to hush money payments made to adult film actress Stormy Daniels during the 2016 presidential campaign. This conviction marked the first time a former U.S. president has been found guilty of a crime.
Following his conviction, Trump’s sentencing was initially scheduled for July 11, 2024. However, after his re-election as president in November 2024, the sentencing has been indefinitely postponed. Judge Juan Merchan granted Trump’s legal team the opportunity to seek dismissal of the case, with motions due in December. Prosecutors have suggested that sentencing might be delayed until the end of Trump’s term in 2029.
Despite the conviction, Trump remains eligible to serve as president. The legal proceedings are ongoing, and the final outcome will depend on future court decisions.
Completely fair and balanced, in other words!
Here’s ChatGPT’s best effort at showing some family fun time reenacting important events in the Kwanzaa founder’s biography:
Ron DeSantis has set up all of the core functions of government so well here in Florida that it is unclear what he would need to do for the next two years (the hated Yale/Harvard graduate will be forced by term limits to leave office in January 2027). Here’s an idea for a Big Project worthy of a politician with Big Skills: develop a new campus for University of Florida that will enable the school to break out of its #30-ish rut among national universities (tied with University of Texas-Austin; #7 among state-run universities).
Why would this make sense? Florida’s population is growing and younger people have been moving into Florida, partially due to the state’s #1 ranking for education in U.S. News but mostly due to the efforts of lockdown governors in the Northeast, Illinois, and California. Florida has about half as many children as California, but only two world-class universities. The first is University of Florida in Gainesville. The second is Florida State University in Tallahassee (FSU is ranked #54 among national universities by U.S. News). California, on the other hand, has Stanford, CalTech, UC-Berkeley, UC-LA, UC-San Diego, UC-Davis, UC-Irvine, and UC-Santa Barbara (8 total ranked #54 and above). There would definitely be demand for another excellent school and Florida has the tax base to make it happen.
Why not expand and improve the schools in Gainesville and Tallahassee? They’re already huge, for one thing (60,000 and 45,000 students). More importantly, if the goal is to build a university that can rank within the top 10, they’re not in the right places. The typical elite academic doesn’t want to live in a small Southern city. Gainesville is unsuccessful at getting UF graduates to stick around and start companies (see Relocation to Florida for a family with school-age children); how is Gainesville going to woo a top researcher away from a school in New York City, Boston, or Chicago?
What are some criteria for where to locate a new university?
Politics. Academics can’t tolerate anyone questioning their beliefs, so they need to live in a city that is dominated by Democrats and where they’re unlikely to ever have a conversation with a Republican. This rules out Miami now that the Latinx have defected to Trump.
Hurricane Risk. Being an elite academic goes hand-in-hand with being a Climate Doomer. This rules out Tampa, whose luck eventually must run out (the city hasn’t been hit by a hurricane since 1926)
Airline Connections. Although elite academics are Climate Doomers, each one has the carbon footprint of a 4 million ton/year cement plant. They need to be able to jump on a flight every few weeks to a conference on the other side of the country or the ocean. You might think that this would bring Miami back into the ring, but nonstops from MIA mostly go to Latin America. Following the lead of Barbra Streisand, the escape route for an American who claims to love Brown people is always to Canada and never Mexico or, God forbid, farther south. Orlando, on the other hand, enjoys nonstop connections to cities around North America and Europe. Everyone eventually needs to come to Walt Disney World and Universal.
High-speed Rail. Intercity rail is catnip for elite progressives. This favors cities spread out along Brightline, which means Orlando, West Palm Beach, Fort Lauderdale, and Miami.
Reviewing the above criteria, Orlando is the obvious choice. It’s one of the few parts of Florida that voted correctly during the Election Nakba of 2024. It’s far enough inland that hurricanes generally lose their strength by the time they arrive over Space Mountain. Orlando is 100′ above sea level, which will reassure even the most ardent Climate Doomer that a vengeful Mother Earth won’t soon reclaim the city as part of the ocean floor. Orlando has great airline connections that will only get better as the theme parks expand. Orlando is going to be ever more connected via high-speed rail as Brightline expands (Tampa is the next big goal).
For recruiting faculty, the state could do a bulk purchase of annual passes (weekday only should be fine since academics don’t need to work M-F 9-5) to Disney, Universal, and Sea World. Everyone who works at UF-Orlando gets passes to all three major parks.
Is this doable? In 2016, the USTA announced the near-completion of a campus with 100 tennis courts on 63 acres next to the big Orlando airport (the plan was conceived in 2014). Celebration, built in the 1990s, is about 5,000 acres and cost about $2.5 billion in pre-Biden dollars to create (home to about 11,000 people, which means enough square footage for a sizable university). The Harvard main campus, which includes a lot of athletic fields, is only about 200 acres. Current Florida state budget surpluses are about $2 billion/year (Ron DeSantis has been using these to pay off debt, but nobody remembers a politician for fiscal prudence; it is acts of fiscal extravagance for which politicians are remembered and celebrated).
One knock against Orlando is that the summer weather is pretty miserable, with an average high of 91-92 in June, July, and August (not hot enough to keep the crowds away from the theme parks!). But that’s actually cooler than Tallahassee and no different than Gainesville and, of course, the academic elite doesn’t have to be on campus during the summer.
Here’s a map showing the new USTA campus in relation to MCO, Walt Disney World (lower left), and Celebration (lower left):
“Palm Beach unanimously approves land deal for Vanderbilt’s new business and tech campus” (vanderbilt.edu, October 28, 2024): In a unanimous vote on Oct. 22, the Palm Beach County Commission approved a deal to provide five acres of county-owned land to Vanderbilt for the development of a new campus in West Palm Beach. For several months, Vanderbilt has been in discussions with city and county officials and community and business leaders about establishing a presence in West Palm Beach to complement the region’s booming financial and tech sectors. The affirmative vote by the county, along with two acres already pledged by the City of West Palm Beach, paves the way for the university to establish a new campus in South Florida focused on graduate programs in business, computing and engineering, bringing high-impact graduate education to what has become known as “Wall Street South.” … Once operational, the West Palm Beach campus will welcome nearly 1,000 students in various business programs … Since 2020, more than $1 trillion in assets under management has relocated to Florida
University of Central Florida, a stepsister to FSU, has 70,000 students in and around Orlando and a dismal #121 ranking from U.S. News
For Democrat friends, the perfect Christmas gift: audiobook of One Way Back, read by the author Christine Blasey Ford (see New version of the Boeing 787 announced: “the Christine Blasey Ford Edition 787, for which the launch customer will be United Airlines. The 787 CBFE is equipped with a fainting couch section for Premier 1K members who are terrified of flying”). Part of the Amazon description:
Her words and courage on that day provided some of the most credible and unforgettable testimony our country has ever witnessed. … This is the real story behind the headlines and the soundbites, a complex, compelling memoir of a scientist, a surfer, a mother, a patriot and an unlikely whistleblower. Ford’s experience shows that when one person steps forward to speak truth to power, she adds to a collective whole, causing “a ripple that might one day become a wave.”
Facebook AI has seen me post enthusiastically over the years about Disney World and also about Japanese gardens in various states and countries. It presents me with this advertisement for what would be an original Thomas Kinkade if Thomas Kinkade hadn’t died in 2012 at age 54 (there was a great profile of him in New Yorker in 2001 before the magazine transitioned to an all-anti-Republican format):
It’s about $780 in 24×36″ size with a rose-colored frame, which I think looks better than the above:
Considering that $780 is on track to be the price of a Diet Coke soon enough, should we be collecting this limited edition of what would have been Kinkade’s original work?
For religious friends, how about these prayer and votive candles from Etsy?
For elite friends with massive fingerprint-magnet Sub-Zero refrigerators… How about this 18×24″ print to go in the middle of a 36-inch fridge or freezer door?
A pilot friend posted on Facebook about his visit to the Sullenberger Aviation Museum, thus prompting me to celebrate Captain Sully’s heroism as the single pilot of an Airbus whose type certificate requires two pilots. He responded that it wouldn’t have been possible for the museum to be named after both Jeff Skiles, who did half of the flying on the flight that terminated in a water landing, and Sully. I turned to my spare brain, i.e., ChatGPT, to find counterexamples.
My prompt: “What are examples of museums named after two people with different last names?”
The giant brain’s answers, on different days:
I tried with a few other LLMs and the answers weren’t quite as useless, but they also included museums that plainly have just one last name in the name. Perplexity and Google’s AI summary (Gemini?) both offered the Nelson-Atkins Museum of Art as an example that fit my query, along with quite a few that didn’t. From the Google:
By giving ChatGPT an example (“the Kamala-Trump Museum of Cognitive Excellence”), I was able to improve the answer, but half of the results were museums that clearly violated my criteria:
It’s interesting, at least to me, how LLMs can be both so smart and so stupid.
The Righteous say that we should substantially reduce our standard of living in response to climate models that show the Earth’s climate trajectory for the next 75-200 years. (This will be effective because there is no way that China and India, for example, will continue to output CO2 once they see us cutting back.) Let’s see how climatologists did with a three-month forecast of hurricane activity.
In August, they said that we’d have 120 days during which a Named Storm was in operation. In fact, we had 77 such days. The Net Tropical Cyclone Activity (NTC) was forecast to be 240% and it was instead 189%. NTC is defined as “Average seasonal percentage mean of NS, NSD, H, HD, MH, MHD. Gives overall indication of Atlantic basin seasonal hurricane activity. The 1991-2020 average value of this parameter is 135.” The definitions needed to make sense of NTC, from a forecast:
I’m not sure whether (so to speak) to be impressed by these weather soothsayers. They overpredicted hurricane activity, but they were correct that hurricane activity would be greater than the recent average. Their results don’t seem to be tainted by going back so far that recordkeeping and measurement techniques were radically different. (See “Changes in Atlantic major hurricane frequency since the late-19th century” (Nature) for the dangers of fooling oneself when using older historical data; the authors of the Nature paper concluded that we aren’t having more hurricanes and we aren’t having more intense hurricanes than we did in the 19th century.)
If the Colorado guys, who might never have seen a hurricane, got the big picture right in 2024 maybe we should have faith in the 100-year forecasts and go green by buying… Tesla Cybertrucks! There is no better way to save our beloved planet than with a 7,000 lb. eco-vehicle. I’ve seen a few without wraps here in South Florida lately and the stainless steel looks fine.
Joel Fajans was the first friend that I made on arrival at MIT (1979) and, sadly, he died last month. He was a gentle soul who never got annoyed by the comparative stupidity of people who didn’t understand physics as well as he did. Although he was generally busy supervising graduate students at UC Berkeley and running experiments at CERN (see “Nothing’s the Matter With Antimatter, New Experiment Confirms” (NYT 2023)) he always had time to answer my questions. I will miss him. If he were alive today I would be asking him “How many rockets can Elon Musk send to Mars before the Earth’s orbit is changed?” Here’s an excerpt from his research page at Berkeley:
And here’s Joel at the intersection of Hollywood and physics:
One of my favorite memories of Joel is when a group of us went on a bike ride from his house in an upscale neighborhood of Berkeley (he saved some money as a young single academic and then married into a bit of inherited wealth). Accustomed to being able to bike in any direction over any terrain on a mountain bike, I managed to ride the borrowed hybrid over of those one-way parking lot tire destroyers and punctured both inner tubes. Joel had a spare tube for one and patched the other and we resumed the group cycle. Joel never complained about or harped on my incompetence.
About half of my class at Comair failed a stage check and received additional sim training, but I got only the bare minimum. My checkride was not too stressful either. The oral exam, which can last 2-3 hours and can include any item of minute knowledge involving regulations, the aircraft’s systems, or almost anything else aviation-related, must by regulation precede the actual flying and it tends to set the tone. The examiner to whom I was assigned was accustomed to humiliating applicants with an opening oral question that none had ever been able to answer satisfactorily. After they realized how ignorant and worthless they were he beat them down for an additional three hours before getting into the sim with the demoralized young pilot.
What was the question? “Why does the Canadair Regional Jet have both an alternating current (AC) electrical system and a direct current (DC) system as well?” As it happened, I had wondered the same thing myself just a couple of weeks earlier. I’d carefully studied the electrical diagrams for the airplane and had a one-hour phone discussion with a friend who is a physics professor at UC Berkeley. Without giving the guy any hint as to my non-aviation background or the fact that I’d discussed this with a physicist, I went up to the whiteboard and gave a 5-minute talk about how Maxwell’s equations explained that a time-varying magnetic field, like you would get from using engine power to rotate permanent magnets, generates a time-varying electric field, i.e., alternating voltage potential. This AC power is ideal for driving the heaviest load on the airplane, the hydraulic pumps for the flight controls (a spinning motor having more or less the same structure as a generator). Having AC power at a high voltage also makes it easy to have lighter wires to move the power around the airplane and then transform down to lower voltage for radios, etc. A transformer will pass AC voltage but not DC.
He said “Your oral is complete. We’re getting into the sim now.”
Searching through my Gmail, I found a good 2007 answer to one of my helicopter student’s questions:
(Student) from Principles of Helicopter Flight, p. 4: “Equilibrium means a state of zero-acceleration. When an object travels in a straight line at a constant speed, its velocity is constant (since there is no change in either speed or direction). It can then be said that the object is in equilibrium. If an object travels at a steady 50 mph on a curve, however, it must be accelerating because its direction is constantly changing and it can then not be in equilibrium.
(Joel) The solar system is in a pretty good equilibrium. (Alright, you can prove that it isn’t but its lasted a long time. A system consisting of just the sun and the earth would be in equilibrium.) The earth is traveling in a circle. So the quote from “Principles…” is incorrect.
A centrifugal force is a fictitious force, but as any fighter pilot would tell you, it feels pretty real.
You are correct that some force must be applied to force a plane into a circle.
However, if you want to pretend that the reference frame rotating with the plane is “normal”, than, in that frame, the forces are balanced…the centrifugal force is balanced by a force from the wings pointing towards the center of rotation.
The question is not profound…just semantics.
Modern thinking on how to teach physics (teaching that I don’t subscribe to) bans mentioning fictitious forces. The claim is that it just confuses the students.
A 2008 discussion about “why treadmill incline makes walking harder”, in which I quote Joel:
I asked Joel Fajans, physics nerd, and he said “consider what happens if you stop walking; you go backwards but also down”. Joel says that if you want to get fancy, you can go for a special relativity-style argument about frames of reference.
Anyway, the incline does in fact make you work harder than simply lifting your legs from a lower position to a higher one. The fact that your body isn’t going up doesn’t mean you aren’t working because the treadmill is creating a new reference frame.
In response to a 2008 question about why airplane generators are rated in KVA (kilo-volt-amperes) rather than in watts:
watts are true power, while kVA are apparent power. The difference has to do with the phase relationship between the voltage and current. With a resistive loads (light bulbs) the voltage and current are in perfectly in phase. Then kVA=kW. But with a pure inductive load (or pure capacitive load) the voltage and current are 90deg out of phase. Inductors (capacitors) do not dissipate average power; there maybe substantial voltages across them and currents, but there is no net power. So the load in watts is zero. The kVA load is not zero…it is the product of the RMS voltage times the RMS current. So what is this extra “load”? It is power sloshing back and forth between the load and the generator…first the generator stores energy in the load, and then the load puts the energy back into the generator.
Loads in the real world tend to be somewhere between perfectly resistive and perfectly inductive, with phase angles in the range of 10-30%.
The amount of coal you have to burn is proportional to the watts, not the KVA (assuming perfect conductors carrying the power to the load.) But in practice, a generator may fry even with a perfect inductor because the instantaneous demanded currents can be quite high. SO on an airplane you would protect for kVA, not kW.
A 2008 exchange:
(me) Can you make [a jet-powered airplane] generator of equivalent power with fewer windings and lighter weight at 400 Hz. compared to 60 Hz? If you want to run the whole airplane on AC power, forgetting about any rectification to DC, does it make sense to use 400 Hz? I figured the 60 Hz. or 400 Hz. would relate more to the speed with which the rotor was spinning and not the number of windings. In that case there is a gearing issue where it would be a lot cheaper to gear the 30,000 rpm power turbine down to 400 Hz. instead of 60 Hz.
(Joel) Running at higher frequencies makes transformers much smaller. For example, I have a 200A power, 10kW power supply that runs at 60Hz and weighs about 300lbs. I have another power supply, which runs at about 30kHz, which supplies 1000A at 6kW which weighs only about 30lbs.
Most power supplies these days are “switchers”. Rather than working at 60Hz to convert AC to high quality DC, they first convert that AC to very low quality DC (glitchy, not well regulated) and convert the low quality DC to 20-60kHz. Then they take the 20-60kHz and convert it back into high quality DC. This takes a lot of extra circuitry, but is definitely worth in terms of weight and cost. All computer power supplies are switchers, for instance. The only down side is that they tend to have noise at the fundamental and harmonics of the switching frequency, which can be problematic, particularly in the sorts of physics stuff I do. (We are fighting such noise at the moment.)
Anyway, the only thing I’d quarrel with is the claim on the web site that there are extra losses at 400Hz. This isn’t quite as simple as described on the web site. Inductive “losses” aren’t really losses…to first order no power is dissipated, so no extra fuel has to be consumed. It simply means that there are voltage drops on the lines. And I can’t believe that its very large.
One issue not mentioned on the web site, which represents a real power loss, is skin depth. See http://en.wikipedia.org/wiki/Skin_depth It turns out that AC current only flows on the outer “skin” of a wire. The skin depth is the thickness of the layer in which current flows. At 60Hz in copper, this depth is about 1cm, but at 400Hz it decreases by the square root of the frequency to about 0.4cm. But this effect doesn’t matter unless the cables are of thickness comparable to the skin depth. I can’t imagine that there are any cables of radius ~0.4cm on an airplane (maybe on an AWACS plane). It is a real problem, however, on long distance transmission power lines.
Joel held strictly orthodox progressive Democrat Cambridge-/Berkeley-style political beliefs. He attributed America’s woes to the existence of stupid/uneducated people in the South, none of whom he had ever met in person. He recognized that California failed to deliver what local and state Democrats promised and assigned 100 percent of the blame for this failure to Republicans because of their role in promoting Proposition 13 and its limits on property tax. (Joel himself was a huge beneficiary of Prop 13 because he and his wife purchased a house in 1999 and, therefore, paid tax on a slightly adjusted original purchase price.) I would point out (a) that California collected a relative high percentage of residents’ income (Tax Foundation) and, (b) California Democrats were in 100% control of the state and could revoke Prop 13, impose a wealth tax, raise income and sales tax rates, charge a congestion fee for use of the roads, etc. This wouldn’t convince him to hate Republicans less. One of Joel’s core yearnings was for higher tax rates and I couldn’t persuade him that the government’s greed was infinite and that, therefore, tax rates were likely already set at a revenue-maximizing level (i.e., to get more tax revenue, the government would have to introduce new taxes, such as value-added tax, not tweak rates; see these charts of revenue vs. rates). Our final political conversation was in March 2024 and regarded the battles in Gaza (I was with him last month, but he was too weak to talk). Joel, an American secular Jew, said “a pox on both their houses”, agreeing with another Jewish Berkeley resident that Hamas and Israel were equally bad. (While this sounds like a nuanced and balanced position, it is highly favorable to the Palestinians. The same people who say that Hamas and Israel are comparable also deny that Hamas was elected to power by Palestinians. Hamas either seized power or is somehow accidentally in charge of Gaza. Once Hamas is gone, Palestinians will revert to
