seriousnotshirley t1_je2h9rb wrote

It was 15 years ago so I probably mis-remembered it. My chem professor did a lot of rotational spectroscopy and had invited someone from HEXOS to give a presentation.

I know the stuff I looked at at room temp looked like a bunch of noise. I tried writing some algorithms to help fix parameters of the molecule to match observed spectra and it went badly above something like 50 K. I'm surprised you were able to pick out transitions near a star! Nice work.


seriousnotshirley t1_jdwdo3q wrote

Something to remember is that general aviation planes don't typically use modern complicated engine designs. Complicated engine designs are one more way for something to go wrong and planes often fly in very different conditions than cars. Moreover, 40 year old planes are flying 40 year old engines, or at least the designs are that old if the engine has been replaced. It's not legal to just swap a new engine type into an old plane.

GA planes also have tight weight tolerances. They just aren't designed to carry a lot of extra weight and so an engine with lots of extra stuff could easily use up a lot of useful capacity, especially on a four seat plane which is really "two seats and luggage" or "four seats and no luggage".

One of the common questions people have is why planes don't use automobile engines since they are commonly mass produced. The issue becomes that you need a transmission and the extra weight of the transmission makes it difficult to convince anyone to even try getting it certified. I only know of one attempt at it.

Using the Cessna 172 as an example since it's so common, the Continental O-300 engine used for many years is a 6 cyl 300 CI 145 HP engine producing about 230 ft-lbs of torque at 2200 RPM. Note: plane engines can't rotate fast because the tips of the propeller would break the sound barrier and the shockwaves would cause issues (and by issues I mean death and destruction). How many 5 liter/300 CI 6 cyl engines do you know of in cars and how many produce much more torque than HP?


seriousnotshirley t1_jdvlmym wrote

Student pilot here, the industry is in the process of moving in that direction. There's a lot of barriers that are slow to get past.

The first thing to understand is that the aviation industry moves slowly and purposely. If a car dies on the highway you coast to the side of the road and usually don't cause an accident. When a plane's engine has a failure that plane is going to need to land somewhere. There's a much higher risk of that causing death and property destruction. Sometimes you're over farmland and get lucky, sometimes you're not. Just google "plane crashes into house" to get a sense of it. There's many many other things that can happen when a plane's engine dies. Because of this the FAA takes slow deliberate steps in changing regulations. One of these is how they certify which engine in which airframes using which gas are permitted. Changes to this need to be certified by someone and for a long time no one had the incentive to do this. I believe getting unleaded fuel certified for most general aviation planes and engines took a change in the way they regulated this, possibly from political pressure.

Next, someone needed to develop an unleaded fuel that can run in existing airplane engines, and there needs to be refinery and distribution capacity. Most planes need 100 octane fuel. While many engines could run 94 octane many need 100 octane. Development on 100 UL didn't start until 2010. FAA certification didn't happen until July 2021 for a single plane (Cessna 172) using a single engine manufacturer. Last September they finally certified it for all planes and engines, though the owner or operator of the plane needs to get a supplemental type certificate for their plane (don't ask me why). Every owner/operator of a piston engine aircraft needs to pony up about $600. Great, except it's not available yet. The developer of the fuel needs to ramp up production capacity and distribution. This is where we are currently at. It's expected to be available in California next year and around the country in 2026.


The next thing is that airports need to start stocking unleaded fuel. Until there are absolutely no planes that require leaded fuel airports will need to stock leaded fuel. Airports serve a public purpose to the flying community by making fuel available. You don't want to leave a big gap in the us where a pilot flying from point A to point B can't get the fuel they need. Now they need to keep another type of fuel. This requires new tanks and either new pumps or trucks. This will be the next roadblock.

If you want to learn more about general aviation you can do what pilots all do and listen to AVWeb’s Paul Bertorelli.


seriousnotshirley t1_j4kxbsk wrote

We look for radiation from hydrogen that occurs when the electron’s spin flips. This releases a photon with a very precise frequency that is seen with a radio telescope. It’s very rare for any single hydrogen atom to exhibit this spin flip but there’s a lot of hydrogen in space so it happens regularly.

While the frequency of the photon that’s emitted is precise the frequency we observe is not. The frequency we observe can be blue shifted or red shifted by the hydrogen moving towards or away from us as we and the hydrogen move around the galaxy.

With an estimate of the gravity of the center of the milky way we can estimate how from out the hydrogen we observe must be for it to be moving at the velocity that it does. That provides a basic model of the structure of the Galaxy.


seriousnotshirley t1_j2909w1 wrote

Newton was the one who really pulled everything together in a fundamental way. Barrow (his advisor) developed a lot of Calculus as did Fermat and Descartes before him and Barrow suspected the fundamental theorem of Calculus but it was Newton who proved it (to the standards of the day) and that was the key to confidently solving differential equations. While the problems of differentiation and integration are what we think of as Calculus that's not really what it's about, it's really about solving differential equations and that's what Newton advanced and then applied to problems of physics of the day.


seriousnotshirley t1_j28zmgk wrote

There's two things Newton did here, one was understanding that things accelerate under a force. For the apple to start falling there needed to be some force acting on it and that force was equivalent to the mass of the object times it's acceleration, which, it put another way, was that the apple was accelerated towards the earth by an amount equivalent to the force acting upon it divided by it's mass.

The second thing was gravity. So what force was acting upon that apple? It was the force of Gravity! That force was proportional to the masses of the two objects divided by the distance between them squared.


Side note: notice that when you take the force of gravity and divide it by the mass of the object being acted upon, the apple, to find out how it's accelerated, the mass of the apple will cancel out by division; and so it doesn't matter of the gravity of earth is acting on apples or bowling balls, the force is the same!

The first is important because under the Teleological framework things had an innate motion towards some ideal state and from this we can start to appeal to faith to divine what things want to move towards. Under Newton's laws things only move when acted upon by some force being applied to them. The second is important because it defines gravity of massive objects as the force that moves objects towards the ground on earth and what keeps the planets orbiting the sun and the moons orbiting their planets rather than the hand of God or some other ideal. Why is this important? It means we can predict natural phenomena rather than appealing to prayer. We can predict the tides, and predicting the tides was really really useful in an age where shipping was economically critical.

Before Newton there were some attempts to predict the tides but they didn't have anywhere near universal success and so people might as well appeal to faith or superstition as they might anyone else who is only sometimes correct. Newton was reliable in his prediction to a point it became hard to ignore... but we've wandered off OP's question here.


seriousnotshirley t1_j1evnbq wrote

Mary was always such a delight. She loved her customers and remembered sone she hadn’t seen in decades. Suan and Dan Dan noodles always hit the spot. Whenever I felt like something off of that list it was quick and inexpensive, no matter which of the random things on the huge menu I ordered.

After the first time I lived in Boston I would make detours on road trips that past anywhere near here just to stop there for Suan.

I hope she and her husband enjoy their retirement and someone in that kitchen takes the recipe for Suan elsewhere. No one else’s is like it.


seriousnotshirley t1_iz27cqt wrote

Are these the only bathrooms? I believe the law in MA is that there does need to be separate bathrooms. You can have a gender neutral bathroom if there are existing separate bathrooms but if these are the only two bathrooms then I don't think you have much room here.


seriousnotshirley t1_iud382i wrote

Don’t just go out and buy a winter coat. You’ll need a jacket, a coat and a “fuck me why did I do this” parka. You’ll want a few varieties of boots from something you might hike in that’s water proof to giant snow boots. You’ll want leggings to wear under your jeans or pants. Even better, fleece lined jeans!

Look for some hiking base layers. Wool undershirts are great, as are wool long underwear though I prefer the leggings.

Hats, gotta have some hats. Warm, thick, wool hats.

Wool socks. Also thick!

Gloves, a regular pair and a “fuck me it’s cold” pair. You can get base layer gloves as well, they work miracles. If your gloves aren’t good enough you stop in every dunks along your way for a regular coffee to hold in your hands.

Here’s why: I’ve been in shorts and a T-shirt in February and I’ve been standing in several feet of snow while it’s below zero. We get such an incredible range of temps from day to day or week to week that you want to be prepared for what’s happening each particular day.

I can from Florida where it usually stayed nice in the winter but you’d get a few days in the 30s or 40s every 10 years or so it got into the 20s and you could wait out the cold stuff. Here you’ll get it all most years.

Last year was predicted to be a bit above average temps for the winter as is this year. It hit 4 degrees F at the airport.

Look at February 23rd and 24th here. That’s what you need to be prepared for.

Oh, one last thing, if you go off the pavement there will be mud. Not sure where exactly you’re staying, but be prepared for some mud when the ground thaws.

Welcome to hell frozen over. I’ll take it every year over Florida summers.


seriousnotshirley t1_iu20y39 wrote

Because they remember how bad the ideas got in the mid 20th century. They were going to cut right through Cambridge and anywhere else they wanted. If the plans back then hadn’t been so awful and pushed through by egos it wouldn’t be so bad but it was awful so we’ve swung so far the other way to making every little town and neighborhood have veto over anything.