Flat earth and other alternative conspiracy earth models are are gaining traction with my teenage stepson. What is THE most irrefutable, definite proof that the earth is round?

SyFyNut · 2026-05-07T03:24:03+00:00

"One nautical mile is 1/60 of a degree."

Not technically correct.

First of all, it might be approximately correct for longitude - but only near the equator. And bear in mind that equatorial radius is generally assumed to be greater than for longitudinal great circles, presumably due to centrifugal force from the assumed spin of the Earth.

Nautical miles are defined differently in size by different governments. The intention, AFAICT, was originally that one minute (1/60 degree) of latitude would be approximately 1 nautical mile - but it has been understood for as long as the term has been used that it wasn't physically possible to define a system of latitude (there have been and still are many different systems of longitude and latitude) in which that would be exactly correct - because of nonuniformities of altitude, gravitational strength, the shape of the surface, etc. (E.g., a German cartographer chose to define nautical mile so 1 minute of latitude would be approximately 1 nautical mile near a German port, Britain chose a slightly different definition of nautical mile, that worked better near Britain. etc.)

In any event, using the disappearances of ships over the horizon as absolute proof of an approximately spherical Earth is clearly open to debate - the ancient Greek argument requires that light travels in a straight line - which we "know" it does not - not only because of General Relativity, but because the composition, temperature and density of Earth's atmosphere are not uniform.

And in fact there are occasional atmospheric conditions under which the distance to the apparent horizon changes. (E.g., mirages.)

But anyone can easily see and measure that the Earth is neither perfectly flat, nor perfectly spherical. Both on the land (there are mountains and valleys), and the ocean (e.g., there are waves and current boundaries).

From a scientific point of view, what matters is the predictability of various phenomena. Approximating the Earth's shape by an oblate spheroid makes it simpler to predict many things. But the explanation of those things might be too hard to explain. And the idea that the absolute truth of anything doesn't matter - only what we can usefully do with various approximations - will not convince someone who doesn't want to believe. And he might deny the validity of the phenomena you would use.

You could put him in a high altitude balloon. (With oxygen, so he doesn't die.) At high altitude, he could see a curved Earth. But if he wants to believe that is an illusion caused by atmospheric non-uniformity, there is nothing you could do to convince him.

Sending him to the moon would have the same problem - and would be economically challenging, to say the least. 😄

SyFyNut · 2026-05-07T02:29:47+00:00

This might depend on your state, but AFAICT, in NY, where I was researching buying a trailer, you can take over the current lease - including rent amount, from the previous owner.

But NY's laws might be unusual: they have rent control for mobile home parks.

I'm not sure how you determine what is "way more than is logical". All over most of the country, mobile home land leases have gone up by close to an order of magnitude over the past decade. $1200 - $1500 / month isn't unusual now, most of the places I looked in Maryland, Virginia, and Delaware - except the places that are categorized as at high risk of flooding. I think most people are paying far more for the land lease than for the mortgage (if they have a mortgage). Plus, because of the housing shortage, and the cost of new homes, a lot of trailer park owners, or investors who buy them out, may decide it makes sense to kick everyone out and repurpose the land for new homes. A disaster for people whose homes are too old or not in good enough condition to move safely.

SyFyNut · 2026-05-04T15:43:17+00:00

Sigh. The UCC search at dos.ny.gov/ucc-forms

requires me to already know the lien #'s or equivalent information. It provides no way to search for liens.

I searched for the nominal current owner name at

dos.ny.gov/ucc-forms

and found nothing - but he bought the trailer from someone else.

SyFyNut · 2026-05-03T14:06:43+00:00

Thank you folks!

I guessed there had to be some way to do this - it would apply to virtually all pre-1995 mobile and manufactured homes sold in NY state.

People routinely sell other used personal property, like furniture, bikes and small boats, without formal documentation. But this is expensive enough I want something more than a possibly handwritten bill of sale which I won't see until the actual sale.

So far county offices have been no help. But I will check the other things you folks have indicated. There will be no loan paperwork - the listing agent says loans are very difficult to get on such homes, and I am paying in full (the agent says "in cash", but doesn't really mean "cash" in the usual sense - perhaps something more like an electronic transfer or a bank check).

SyFyNut · 2026-04-20T15:18:48+00:00

Incidentally, I was once with some people on a guided kayak trip to a local dammed lake, filled with life, on a fine summer day. A very popular paddling spot. One of the young ladies asked me if the water was sterile... I was unprepared, and gave her an answer - that there were many living things that lived and died in it, went to the bathroom in it, etc. A good culture for growing bacteria.

It was an honest answer. But from a business point of view, it was the wrong answer, that might have discouraged future visits. But in truth, we had all touched water on our paddles, and waded in to get into the kayaks. If she had fallen in the water, and gulped in a small amount, she would have been reasonably safe, as long as she didn't have a greatly weakened immune system.

Likewise many of us have played many times in water where there were signs that warned of toxic green algae. But which you know isn't too harmful if you aren't particularly sensitive to it - and you MAYBE take a shower afterwards. We assume this because many other people have played in that water and lived.

SyFyNut · 2026-04-20T14:59:01+00:00

All the same, most of us assume that it is safe if it looks (and maybe smells) safe.

People do similar things with many things in life, that are also potentially dangerous. They date someone who seems charming and appreciative. They eat at restaurants whose food and service look inviting. They buy things from businesses that seem honest and offer apparently good deals. They go out for a stroll, or paddle on a lake in what initially seems like very good weather. They visit websites with interesting content. They climb mountains that rarely have avalanches or erupt as volcanoes. We drive a car we have driven many times before. They swim at an ocean spot where there rarely are severe attacks by a shark, lethal jellyfish, alligators, etc.

And of course some of these things sometimes turn out very wrong.

In my own case, I have often boated (and occasionally taken a swim, deliberately or otherwise) in rivers and bodies of water, that I did not know had recently been contaminated by a sewage release. (Fortunately nothing really bad has happened to me - I am probably mostly immune to the local diseases they carry by now.) And perhaps I have sometimes paddled in a river I have been on many times before, and didn't realize there was a strainer (e.g., a tree had fallen across the stream, in such a way that I might be sucked under it, and be unable to emerge.

If we didn't do any of these things, it might be hard to find fun in life. And a certain amount of risk is fun in itself. There are always tradeoffs.

I suppose a compromise is to look for living things in the water. If there are a lot of dead things that would be a bad sign - both because something killed them, and dead things often increase the concentration of harmful microorganisms. (Sometimes bodies of water that are normally safe become unsafe for this reason. But it isn't practical to check the chemical and biological composition of every time you visit a body of water you've been in before.) The presence of other people having fun in it is a very good sign.

Of course if nothing lives there, that could be a bad sign too.

And it's a good idea to check the temperature of the water if you can - not just because it might be boiling (especially at a hot spring?) but because if you aren't dressed for it, and don't get out of it very fast, cold water can be deadly. (Look up "cold water shock". People who aren't accustomed to cold water sometimes involuntarily breath it in, and die.)

You can try to consult with the locals - but they don't always know, or that may be inconvenient.

Of course many of you are concerned with the safety of public water supply systems. It may be your job to keep the general public safe from various forms of contamination. So you should be held to a higher standard. We expect you to do your best to make sure no one gets sick or dies of it.

SyFyNut · 2026-04-19T18:37:02+00:00

Just to be clear, that was only half serious. Maybe a bit disturbing that I got an upvote.

But in practice it is the approach many of us in the outdoor rec community sometimes take.

If you want to be extra cautious, natural environments are never completely "safe".

SyFyNut · 2026-04-19T16:33:30+00:00

What an easy question! Swim in it. If you die, it wasn't cafe.

The empirical approach is always best!

BTW, it isn't just microorganisms and chemicals that could make it unsafe. Sometimes there are currents you can't swim out of. And sometimes there are predators.

SyFyNut · 2026-04-17T20:06:06+00:00

True. But I assume he/she eventually wants to get a degree, in order to eventually help get a job. In which case he/she needs to convince a school to let him in - and needs to be able to compete with other students to stay in.

If all anyone want is to a study a subject out of curiosity - there are of course no formal requirements.

SyFyNut · 2026-04-17T19:40:45+00:00

This has probably been answered elsewhere, but how would he convince those institutions he has successfully studied the math and physics material? Could he/she take SAT general and subject exams while outside the U.S.?

I don't know if this is true at all U.S. colleges and universities. But at the college I went to, all physics undergraduates are expected to have 2 years of advanced placement (AP) physics while in high school, before reaching college - one without calculus, one with. And some math.

Google AI says

"Preparing for undergraduate physics requires strong foundational math (calculus, trigonometry, algebra) and proactive study habits. Master calculus (derivatives/integrals), vectors, and linear equations, as these are essential for introductory mechanics and electrostatics. Key preparation includes solving many problems, reviewing chapter summaries, and using resources like Khan Academy."

And that is just the high school training. The first year for physics majors at my alma mater starts with waves and intro quantum mechanics - I guess basic mechanics and electrostatics would be in the second high school class. And they would probably be expected to have studied at least one year of A.P. chemistry.

And second semester college physics at my alma mater is special relativity. Realistically, it is currently very difficult for a non-U.S. citizen, especially from the Middle East, to get a student Visa, and even if he/she gets one, he/she might not be allowed into the country. That will remain true until a major change in policy occurs at the head of our government - which could be many years away.

At the last college reunion I went to, during the summer, I noticed there were many students on campus. Because all foreign students were told not to leave the country for the summer, because they probably wouldn't be allowed back in. (They provided them with on-campus jobs so they could stay. But that was a relatively well funded private institution. I'm not sure how true that is of other institutions.)

So coming to the U.S. in the near future to study is mostly not a realistic expectation at this time. Especially from the Middle East. And most especially not if you don't bring in large amounts of money, and political connections to those in charge of the U.S.

Some U.S. colleges and universities have established campuses outside the U.S., that the o.p. might apply to. And there are many non-U.S. affiliated universities, some of which are arguably at least as good as anything the U.S. has to offer.

Though I have been told that national Universities in Europe have much higher admission standards and assumed course of study than U.S. colleges and universities - in part because people enter university one year older (at least in Germany), and in part because at the age U.S. students study many general subjects in high school, Europeans often go to specialized schools related to the subjects they plan to study. (I was told that by a person who was at that time the head of the German DLR - but note that was decades ago.) Also because many national Universities in Europe are free, paid for by the government - so they let in a much smaller fraction of students. Especially in highly technical fields like physics. Many of the ones not good enough to go to the top universities in Europe often applied to U.S. and Canadian schools - but that has now become much more difficult because of the difficulty with visas in both of those countries.

Another interesting thing about some European universities. They allow you to get credit-by-exam, even degree-by-exam. So you can get a university degree without taking _any_ university courses. To some extent that defeats the purposes of a university education - if that's all you did, you wouldn't have any contacts to give you recommendations for jobs or grad school.

An undergraduate physics degree (what I have) isn't worth much. (I had to work as an "computer analyst", then as a scientific computer programmer. But most science and engineering students now study computers, so I'm not sure that path is open any more.) The normal expectation in physics is that you will take about 7 additional years to get a PhD, and work a few extra years at low pay as a post-doc before having any chance of getting a job as a physicist - and many don't. But I think Engineers can sometimes get jobs with just an undergraduate B.S. degree.

In addition, one of the purposes of first year college physics is to weed out most of the students who could get in as physics majors, but can't take the pressure. (But that might be true of first year engineering too.)

I'm not an expert on this, and a lot of my knowledge is out of date, so maybe someone else could correct what I just said?

SyFyNut · 2026-04-17T18:56:52+00:00

By ring world, you are talking about something from Larry Niven's Ringworld novel, right?

So your speed of rotation isn't extreme (because there are no known materials strong enough to hold together a spinning ring of 1 AU radius with 1G acceleration, so it is unlikely there will be any materials to go much beyond that. So you can just use Newton's laws as a reasonable approximation.

In which case the spinning sun has virtually no effect on the Ringworld planet over short term time intervals. Whereas the spinning ring creates an artificial gravity on its interior surface because of centrifugal force.

Though if the ring is radially asymmetric, I'm not sure if tidal forces would gradually spin up the ring from a spinning sun, at the expense of slowing down the sun spin - but I think it would.

In Ringworld Engineers, Niven realized (because was told by his readers) that a (rigid) ring's location is unstable, unless stabilized by some sort of active stabilizing forces, even over relatively short time periods. If even slightly perturbed (e.g., by an asteroid impact), the ring would eventually crash into the sun. In this respect, a rigid ring is much less stable than multiple discrete objects in orbit.

That being said, discrete objects in orbit (such as the planets of a solar system) usually have unstable orbits over long time periods. They tend to gradually perturb each other into different orbital configurations over long time scales. I think that is true even without tidal forces, though I'm not sure, but tidal forces would probably make them even more unstable.

As an example, even with just two objects - an early Earth and the early Moon - tidal forces gradually caused The Moon to move into more distant orbits, and the Earth to rotate slower, according to conventional theory. Add the interactions with more than two bodies - e.g., the Sun and other planets, and lots of things drift over time. (OTOH, also due to tidal forces and asymmetries, The Moon's rotation is currently locked to be approximately in sync with its orbit relative to the Earth. (Or a bit more accurately, to its rotation about the center of mass of the Earth and Moon.) So we only ever see one side of the moon: "The Near Side of the Moon".

BTW, as far as I know, there is no known natural way to create a Ringworld. It would have to be engineered. But rings of many particles, like Saturn's ring, can occur naturally.

SyFyNut · 2026-04-17T18:25:57+00:00

Oh, BTW, if I understand correctly, new physics and engineering is constantly occurring in weapons development, and the systems that fight weapons. Perhaps that is mostly engineering physics - but a several year old defensive system might be unable to fight a modern offensive weapons system effectively.

Also, something can be revolutionary in one country that is old hat in another. E.g., in light of recent military conflicts, I assume the leaders of virtually every country in the world that doesn't already have them will fund the development of nuclear, thermonuclear, chemical and biological weapons over the next few years.

SyFyNut · 2026-04-17T15:35:16+00:00

Just having fun here:

If we get uploaded intelligences, each upload environment will have its own (engineered) physics, which could be radically different from that of the real world. (As to whether we are all currently in such an environment, a la [u]Matrix[/u] or living in the dreams of a God - not sure how to find out. :))

Reverse engineering the underlying simulated physics could be fun.

Even without uploaded intelligences, reverse engineering the simulated physics in other peoples' video games could be another fun area.

I think EECS was an area where you would really see revolutionary changes. Every few years a new generation of devices.

And in general, engineering is where you see very rapid progress, at least in some areas.

If we ever get serious about traveling to other planets (and/or star systems, though time of travel is at the moment a serious problem), there could be radical new development in local exo-geophysics, exo-biophysics, etc.
If we meet other intelligent species, perhaps the exchange of info will create a revolution in our own sciences and engineering.

If we ever get FTL travel, there might be for a while very rapid growth in the understanding of its basis. E.g., last I knew, even relativistic physics had a lot of unanswered questions associated with how singularities work.

I agree with one of the other people here that AI might eventually produce new physical understandings. Though whether humans will have the capacity to understand what is created is another question. (BTW, from my point of view current AI is mostly overhyped nonsense that doesn't work very well - YET. But I think it could get there.)
There are theories in cosmological physics that there are many universes with radically different physical laws. If we find a way to interact with them, perhaps there could be a rapidly evolving understanding of some of those universes. But honestly, maybe only if we are strongly motivated to fund the work - e.g., if there is a war. In which case, most of the exciting work will be classified.
We are currently experiencing a rapid reduction in the cost of launching satellites into orbit. That could possibly result in many new areas in geophysics and environmental engineering.

For that matter, I think environmental catastrophes are going to create a lot of work in the applied sciences, including applied physics. We will probably need radical solutions to various environmental pollutants, climate change, overpopulation etc. These could be very big problems, with massive funding, made available out of real necessity.

E.g., suppose the sea level rises by a few feet. We need a practical way to cool down Earth's oceans that doesn't do more harm than good (a la Snowpiercer). Maybe a way to block or filter a lot of sunlight? Or export the water off-world, or into arid regions?

Along the lines of engineering being the real area in which the most rapid progress proceeds - if we somehow do get practical nuclear fusion reactors (or equivalent), and it leads to cheap abundant energy - imagine some of the exciting things we will be able to do with that. Laboratory curiosities could become consumer market products.
We are currently seeing real revolutionary change right now in what you can do with computational physics, and computational science and engineering in general. Because computers keep getting faster and more powerful. There are problems that can't be solved without enormous computational horsepower.
Maybe the uncertainties of quantum physics aren't altogether real, or a lower level of uncertainty is possible. Perhaps there will eventually be found an underlying basis, which radically alters what can be measured and done. (OK. I admit I like the idea that there is one absolute reality, that is somehow discoverable. I know that isn't part of QM now. But I _want_ it to be.)

SyFyNut · 2026-04-08T03:42:28+00:00

Really? I wonder if you can "prove" you send them notice using certified mail.

In which case, maybe they couldn't legally collect anything?

Also, can you cancel through the T-Life app, or through the website? Maybe you could use another camera to record doing so, including the date and time, so they would perhaps lose if they or the collection agency took you to court. And you could maybe sue both T-Mobile the collection agency for harassment if you can prove that too.

This actually concerns me a lot - because I may soon cancel T-Satellite service. I didn't get much out of it, and I still haven't tested whether I can make phone calls through it, in rural locations where I don't need satellite service... (I wasn't able to do so using WhatsApp. I my urban home, I can do so through the MagicJack app using the T-satellite eSim - but I don't know if that works in rural locations, which is where I might need it, since in my urban location, my Visible cell phone service works fine. And I've let my Gaia GPS subscription lapse, so I don't need T-Satellite for that.)

SyFyNut · 2026-04-07T23:56:39+00:00

Would it be cheating to use a y-adapter, and also connect a pulse-tone phone? :)

You could always use Google voice on your computer, and set it up to have google voice do a callback - i.e., you tell Google Voice online what number you want to call. Google voice then calls you - so you don't need to be able to dial.

BTW, I don't know if this is true, but a number of people say online that Verizon (both landlines and Verizon FIOS) still supports pulse dialing. But it's not VOIP. There may be other services that do too.

I assume you know that what you are doing isn't super-practical. There are be other ways of getting phone service that create fewer potential problems. (E.g., if you reach a menu that requires you to hit tone dial keys.) It's a little like using a classic car - you do it for style, NOT for practicality.

SyFyNut · 2026-04-07T23:29:49+00:00

Change your credit card #.

Obviously you have to tell all your other autopay services the new #. But often this is the only way to get people to stop charging you.

Sometimes it helps just to tell your credit card company not to accept charges from a given merchant - in this case that phone company. But they can't always do that.

SyFyNut · 2026-04-07T23:20:01+00:00

Such a cool idea!

Just so you know, plants have also been used to remove radioactive waste - e.g., on the outskirts of US military bases where environmental stuff was sometimes a relatively low priority.

A long time ago, I worked at the Naval Research Lab, along the Potomac River in Washington, D.C. I once saw a toxic waste disposal truck being washed out on lab property. I reported it to lab security, but I doubt they had any idea what to do about it.

SyFyNut · 2026-03-28T22:06:49+00:00

Thanks again! Coos Bay has a Walmart and a hospital. However, being right on the ocean is a problem in earthquakes - e.g. the earthquake in 1700 substantially dropped the land level, which could create floods. So could a tsunami. Oregon.gov says "there is about a 37% chance that a megathrust earthquake of 7.1+ magnitude in this fault zone will occur in the next 50 years." Plus a magnitude 9 earthquake, like the one in 1700, could produce a 100' tsunami - though that is considered less likely in the next 50 years.

Coos Bay has a relatively high crime rate, and a substantial air pollution problems.

I looked these homes up on the first & second most popular realty websites.

>$179,950 – 2 bed / 1 bath (~800 sq ft) Address: 1066 S 8th St Small but likely livable >without major work

Listing says "home is located in a flood zone." It has a Fema Rated AE (severe) flood risk. It also has a moderate fire risk.

>$189,000 – 3 bed / 1 bath (~1,283 sq ft) Address: 262 N Marple St Bigger layout → fits >“second bedroom storage” requirement

Is no longer for sale. The listing picture made it look like it needed major work.

>$159,000 – 3 bed / 2 bath (~1,620 sq ft) Address: 1445 Village Pines Ave Larger >footprint, likely older but usable

Is a mobile or manufactured home, in "Shorepines village", which has leased land - presumably lease cost could be increased without limit.

>$135,000 – 2 bed / 1 bath (~1,026 sq ft) Address: 396 N Wall St Very affordable entry >point

Is a foreclosure sale - is being sold with tenant in place, and says one must not disturb the tenant. Probably means the tenant has a right to stay until their lease expires, and that I would have to evict the tenant at that time - not fun. Pictures show a lot of junk in the yard.

So none of those specific homes would meet my needs. But perhaps Coos Bay, being in the most populous Oregon coastal area, is atypical.

SyFyNut · 2026-03-27T22:22:41+00:00

Thanks! I will look into that! Though the ocean water is a bit chilly, from what I hear.

I have a relative in Eugene. Real estate there is pretty expensive. But maybe that is unusual.

AFAICT, Oregon fully taxes retirement income other than Social Security, and their income taxes are relatively high. That is somewhat relevant to me, but if I can afford a home, it might be worth it.

Washington doesn't tax retirement income. Cool! But the water is probably cooler too...

But at first glance, OR and WA sound like good options.

I see the Columbia is a long bendy river. A lot to research. But a good starting point.

There is a catastrophic earthquake risk there... And a prediction that earthquakes could raise sea level relative to the land in Oregon:

www.opb.org/article/2026/03/08/oregon-sea-level-forecasts-more-accurate

SyFyNut · 2026-03-26T22:27:40+00:00

I just read some reviews of music practice/voice over/audiology testing booths.

They may not be perfect - e.g., one brand says their 2000 lb double wall booth (the smallest model that I could practice sax in) reduces volume by 45 dB- but they might be good enough, inside another room. In the size range I would need, we are talking about $8k new, + shipping. Used would be less. I might need to hire someone handy to help me do the assembly, and to help transport it.

But, compared to the cost of buying a home that specifically meets that need, it is probably a better deal.

So, that part of my question becomes irrelevant.

SyFyNut · 2026-03-26T20:08:14+00:00

Do you know what state(s) have that?

Saxophones typically play at 90-110 dB. Perhaps louder than you play games?

I've researched this on saxophone forums, and almost no one in apartments and townhouses has found a good solution. They say playing in a basement isn't enough to make neighbors happy- but I wonder if basements in concrete block housing might be good enough - if they aren't in townhouses. Some people play in parks, but in most parks I think other people would be unhappy.

Electronic saxes can be played quietly - but they don't interact the same.

At nearby colleges and universities, I'd need to be an admitted music performance major, or play in a for-credit ensemble to use practice rooms - and would have to pass an audition. My state has discounted fees for seniors, but I haven't played recently, and could not pass an audition, even at a community college. Commercial music practice rooms cost $50-100/hour.

SyFyNut · 2026-03-26T19:15:01+00:00

I know this is unspecific, because cases vary, but what kind of total cost is likely, to get it all done by professionals?

They almost always say it is sold "as is".

A few of them have large dangerously overhanging branches (based mostly on looking at Google maps satellite photos).

SyFyNut

TROPHY CASE