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.]
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
Separately, has anyone seen anything from a leader within the Party of Science congratulating Elon Musk on what seems like a tremendous step forward for actual science? (I disagree with Mr. Musk regarding the merits of humans living on Mars, but it is valuable to be able to send heavy robot payloads into space and the Starship makes NASA’s ($40 billion in 2024 dollars?) SLS look pathetic.) If Democrats love to Follow the Science why aren’t they more jazzed up about Starship today than about Donald Trump’s agenda (the above tweet from Kamala Harris was sent just a few hours after the Starship booster was caught).
Nobody will remember Joe Biden or Kamala Harris in 100 years because they achieved absolutely nothing. But every child will know Elon Musk the Rocket catcher. Congratulations Elon.
(While trying to avoid extradition, Kim Dotcom manages to tweet his support for Hamas: regarding the “Gaza genocide” (exacerbated by simultaneous rapid population growth); accusing Israel of “indiscriminate mass murder”; a confident “proof” that Israel “Netanyahu can’t defeat Hamas in a ground battle” (Nov 19, 2023; maybe he was correct since Palestinians remain enthusiastic about continuing their war against Israel).)
I hope that we can all agree that whoever wins the Nobel Prize in physics is either the smartest person in the world or very close to having that distinction. This year’s smartest person is Geoffrey Hinton (WSJ):
Hinton has been fielding a new request to talk every two minutes since he spoke out on Monday about his fears that AI progress could lead to the end of civilisation within 20 years.
But when it comes to offering concrete advice, he is lost for words. “I’m not a policy guy,” he says. “I’m just someone who’s suddenly become aware that there’s a danger of something really bad happening. I wish I had a nice solution, like: ‘Just stop burning carbon, and you’ll be OK.’ But I can’t see a simple solution like that.”
In the past year, the rapid progress in AI models convinced Hinton to take seriously the threat that “digital intelligence” could one day supersede humanity’s.
“For the last 50 years, I’ve been trying to make computer models that can learn stuff a bit like the way the brain learns it, in order to understand better how the brain is learning things. But very recently, I decided that maybe these big models are actually much better than the brain.
We’re doomed, in other words. In the meantime, though, we should vote for bigger government:
“I’m a socialist,” Hinton added. “I think that private ownership of the media, and of the ‘means of computation’, is not good.
Let’s check in with our future AI overlord to see how the “new flagship model” does at arithmetic:
This calculation is explained confidently, but seems obviously wrong. The Biden-Harris administration gave away $170 billion in taxpayer funds to gender studies graduates and drop-outs (“student loan forgiveness”). At $1 million/day and zero interest it would take 170,000 days to pay off this single act of largesse. All that is required to do this in one’s head with middle school skilz is 170e9/1e6 and then 9-6=3 so we have 170e3. If we want to turn 170 thousand days into years we can see that works out to about 500 years because 170 can be approximated as 365/2.
So Hinton is saying that AI will go from not being able to do arithmetic or reason in orders of magnitude to destroying us all in 20 years.
Related…
Physicists learning how it feels when AI takes their jobs…
The NASA pavilion at EAA AirVenture (“Oshkosh”) 2024:
(These are the plastic bags that are good for the environment?)
What else was going on? NASA arranged to have a Boeing Starliner parked in front:
The NISAR mission was featured. This was supposed to be launched in January 2022 and will supposedly be able to measure displacements of parts of Earth’s surface as small as 3.5 mm. I’m not sure if this includes vertical displacement, e.g., to see whether sea levels are indeed rising to the point that owners of multi-$billion lower Manhattan and Boston real estate portfolios need to be bailed out by taxpayers in the Midwest. The satellite will supposedly be able to watch glaciers and ice sheets moving. I don’t think that it can measure sea level directly because the Science Users’ Handbook says “Provide observations of relative sea level rise from melting land ice and land subsidence.” How many migrants could have been housed for the cost of this mission? “NISAR launch slips to 2025” (July 29, 2024) says “with NASA alone spending more than $1 billion in formulation and development of the mission”. Taxpayers spend about $200,000 per year per migrant family welcomed in New York ($140k/year for food and housing and then let’s assume another $60,000/year for health care and other benefits). So if we hadn’t spent money on NISAR we could have supported 1,000 additional migrant families for five years.
NASA was also featuring the X-66, a collaboration with Boeing on an airliner that could possibly cut fuel burn by 30 percent, mostly via high aspect ratio wings (as you might see on a glider). We’re in a “climate crisis” according to our ablest minds, e.g., Kamala Harris, and “communities of color are often the hardest hit”. When will communities of color see some relief from the X-66? NASA says that if everything goes perfect the X-66 might get into the air as soon as 2028 and then, in the year 2050, we’ll be in a net-zero phase for aviation. The United Nations forecasts that world population will grow to approximately 10 billion by 2050. So we’ll have more people taking more trips, mostly in planes that were built to current designs, and the result will be much less environmental impact.
Today was another tech triumph for Elon Musk, but I have a question: if there aren’t a lot of fat humans who want to go to the Moon or Mars, what will we be lifting into space via the (apparently almost ready for real use) Starship? Aren’t most of the things that we want to send into space getting lighter, e.g., communication satellites? “Average Commercial Communications Satellite Launch Mass Declines, Again” (2015):
The average size, or launch mass, of commercial communications satellites is declining. After the average launch mass reached a peak of 4,424 kilograms in 2012, it declined to 3,578 kilograms in 2013 and 2,755 kilograms in 2014. Even the launch mass of geosynchronous satellites, which are typically heavier than LEO spacecraft, declined in 2014. The launch mass of GEO satellites peaked in 2013, when it reached 5,288 kilograms. The average launch mass of geosynchronous satellites declined to 4,276 kilograms in 2014.
Could we get more scientific information about the other planets in the Solar System if we sent heavier robots to them? The Curiosity rover weighs 2000 lbs while Perseverance is 2,260 lbs. Sojourner was only 25 lbs.
How about space-based telescopes? Optics and mirrors are heavy. Maybe Starship will make launches so cheap that every astronomer can have as much space telescope time as he/she/ze/they wants.
The next total eclipse that will reach a significant number of Americans is headed straight for Jupiter, Florida! It will last for a remarkable 6 minutes. From timeanddate:
I’m not sure why they say that the average cloud cover is 64 percent. I would have guessed that 1:30 pm in August would be blue skies with a chance of thunderstorms. It would probably be smarter to travel to Nevada, but then it wouldn’t be possible to observe the eclipse from one’s own swimming pool. Here’s an August map from an eclipse nerdism site:
(some folks in Montana, North Dakota, and South Dakota will see a 1.5-minute eclipse around sunset on August 22, 2044)
Houlton, Maine has at least two downtown tattoo shops. While passing the one below I shouted out to my companions, “Brainwave: We get a tattoo with the city name and date every time we watch an eclipse.” This idea was topped with “It has to be a face tattoo.”
The Canon mirrorless 800/11 lens is light enough to pack for Eclipse 2026 in Spain (or Iceland if you feel extremely lucky with the weather).
How well does it work for photographing totality? The magnification seems about right for photographing the full corona. Here is the entire JPEG out of the camera at 1/250th of a second and ISO 400 (no need to spec the aperture because it is always f/11):
With an exposure of 1/13 of a second, the corona gets quite a bit larger:
The camera was set to autofocus and fixed at ISO 400. It was mounted on a cheap light Slik ballhead tripod that I happened to have available in Boston (we flew from KBED to KHUL (Houlton, Maine, the last stop in the U.S. for Eclipse 2024) and these pictures were taken from the ramp at KHUL).
It’s tough enough to aim at 800mm and I certainly wouldn’t want any higher magnification without a star-tracker camera mount.
I’m generally negative on trying to photograph the eclipse. The great images are nearly all stitched together laboriously in Photoshop based on multiple exposures, e.g., one long enough to capture some details in the moon itself and the farthest reaches of the corona and some short enough to show detail in the corona right near the surface of the sun. It’s better to leave the documenting to the nerds with infinite Photoshop patience and bulky equipment and park yourself with a great pair of binoculars to simply enjoy the show.
Here’s a Photoshop special from NASA in 2017 that looks great but bears almost no resemblance to what you can see with your eyes or with a camera in a single image:
Here’s the ultimate example of the “f/8 and be there” principle of photography (an experienced photographer’s technical-sounding advice to a beginner):
Kendall Rust (Facebook post) says she took it in Jonesboro, Arkansas and that this is straight out of the Canon camera, though it looks like a Photoshop wizard created it! CNN shows a remarkably similar image and credits it to Bobby Goddin:
Here’s yet another:
Unless you’re Kendall Rust, Jack Emshwiller, or Bobby Goddin, though, I’m going to stick with the “just enjoy totality” advice and take some images of things that happen around you just before and after totality. (What if you are Kendall Rust, Jack Emshwiller, or Bobby Goddin? My advice is that you abandon your hatred of government-created inequality and load up on Powerball tickets the next time the jackpot reaches $1 billion!) Here’s a quick iPhone picture of the pseudo sunset:
But if you’re going to ignore my advice, the Canon 800/11 seems like a great choice! It’s cheap, light, and does the job pretty well.
I had some worked planned in Austin, Texas over the weekend, which dovetailed nicely with the predicted eclipse and the generally clear skies in this dry part of the country.
Inmates at a New York prison who sued the state corrections department over a planned lockdown during the Monday total solar eclipse will be able to see the celestial event after all.
The lawsuit filed Friday in federal court in upstate New York claimed that the lockdown, which would have prevented many statewide inmates from witnessing Monday’s solar eclipse, constituted a violation of religious rights.
“For many, this eclipse is a moment of monumental religious significance that cannot be overlooked or dismissed out of hand,” according to the lawsuit, which listed six plaintiffs of various religious faiths.
Corrections officials agreed Thursday to permit the plaintiffs – a Baptist, a Muslim, a Seventh-Day Adventist, two practitioners of Santeria and an atheist – to view the eclipse in exchange for the lawsuit’s dismissal, department spokesman Thomas Mailey told USA TODAY.
Practitioners of Santeria also trace historical ties to chanting rituals performed during a solar eclipse. For atheists, an eclipse may not be a time for worship, but it’s still a time to marvel about the natural wonders of the universe, the lawsuit contended.
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Nervous nail-biting began on Wednesday, April 3 based on the cloud forecast at https://eclipseweather.info/eclipse/. It appears that God loves Bernie Sanders and fellow progressives in and around Burlington, Vermont. God also loves folks in Arkansas, Missouri, Illinois, and Indiana. Why does God hate Texans?
I’m testifying as a software expert witness in Federal District Court in Newark, New Jersey on Wednesday. Getting to EWR from Austin on Tuesday was $2,000 in economy. Flights to JFK were about $1200, with no difference in cost between economy and first class. But it would have been well worth it (to the client!) if the weather had been clear.
https://www.pivotalweather.com/eclipse2024/ is also an interesting site. The “NWS Blend” cloud cover forecast as of the evening of April 4 wasn’t promising for just west of Austin:
Pivotal displayed a tempting map of Vermont and Maine:
Based on these forecasts, I canceled the Austin flights and booked a trip into Boston. From there we departed to Houlton, Maine on the Canadian border (passport and blackface kit packed just in case). The terminal forecast from 8 pm Sunday:
The relevant part is that from 15Z (GMT; subtract 4 hours to get 11:00 am EDT) on the 8th the wind would be from magnetic 300 (NW) at 7 knots, better than 6 statute miles of visibility, and a few clouds at 25,000′ above the airport.
Who has plans for North Dakota or Greenland in 2044? Don’t want to wait that long? Looks like Spain is the smartest place to be (the weather in western Iceland is not reliable!) on August 12, 2026. Has inflation gotten so severe that hotels won’t let people book more than a few months in advance?
Readers: let’s hear your heroic eclipse-viewing tales!
Post-trip update: The weather was just as forecast. We had severe clear weather and a great view of totality as well as all phases of partial. The town organized a warm welcome for thousands of visitors.
