I am looking for practical ways to prove the Earth is round using materials accessible to the average person. I have zero interest in disproving Flat Earth folks.

I am inspired by Dan Olson's (Folding Ideas) excellent video where he is able to do this measuring the curvature of a lake near his home that has a very specific geography that lends itself to this sort of experiment. I've seen all sorts of ways to prove this measuring shadows and poles, using gyroscopes, etc. and wanted to know if there are any practical guides for proving once and for all that the Earth is round for yourself relying on nothing more than experimentation.

What I'm not looking for:

• Math relying on flight times/charts
• Video/picture evidence
• Deductive proofs built on agreed upon premises
• Expensive tests
• Extremely time consuming projects
• Underwhelming results (relying on a probabilistic argument for a round Earth from the evidence.)

What I am looking for:

• Practical experiments
• Things I could potentially do without spending much money
• Tests that aren't largely comprised of accepting someone else's research
• Potentially math-heavy evidence
• Results that are strong and conclusive

I've thought of finding some easy to test version of Eratosthenes' proof using two poles. I've also thought about using a balloon and sending something to space like what is done in this Tom Scott video. Nothing seems well documented in such a way as for me to be able to follow it at home.

TL;DR: I think it would be a meaningful experience to have the power to prove the Earth is round by myself, for myself. I can only compare this desire to the desire a child with a telescope has when wishing to observe Saturn or Mars themselves for the first time. It's not to prove anything or to settle doubts, but for the personal value of independently observing this astronomical fact oneself.

Greetings Folks, I apologize if this is the wrong spot for this but I'd like to cast a net to see if I can get any additional thoughts or help.

I recently started a new job as NGS Library Prep Tech - sadly I had only begun training on this briefly at my last position but only got an introduction to Speed/Mag Bead clean up. I was hired because the lab is growing quickly and has had issues with organizational stuff in the past and that is my strong suit (my last position I did a lot of clonal DNA / miniprep stuff as far as the wet work went).

The person I was replacing at my new job was only there for two days and didn't really help a whole lot other than hand me a haphazardly written protocol and said "practice by cleaning ladders at different bead concentrations and running them on a gel."

Did that and was told they look good.

Fast forward to using actual samples: There were a set that needed to be redone because the final pool was lost. When I did my first qubit quants after the post PCR speed bead clean up I noticed that the quant concentrations were ~80% less than what they had been previously.

Today I have some remaining sample that I can push through PCR, my plan is to quant 8 out of the 53 samples of the pre / post PCR plate and then again after I do clean up.

As far as clean up goes I had been trying to do the whole plate at once, but I'm going to go back to just completing a column at a time to ensure my timing is better.

Are there particular spots in the Speed / Mag Bead clean up process that I should be aware that I could be washing away / losing DNA?

Do people have any tips on how to be more 'sure footed' in this process?

Ways that I can better practice and say "yup, I've got this!"?

Thanks for the help, and if this should be posted somewhere else please let me know, but as this is 'science' related I thought it fit best here.

I used to work with a guy who had three PhD's. (two in Europe, one in the US). He had them in math, chemistry and biology. He said a few fairly outlandish things over the timeframe that I knew him, but every one I ever dug into it turned out was basically accurate.

One of the things he mentioned in passing, but which I haven't been able to confirm to my satisfaction is that when plants reach certain high temps, they start producing H2O2 instead of H2O. (around 45 Celcius)

I've read a few papers that seem to indicate that part at least is true, but I've never found anything that says whether or not this puts plants into the 'consumer' column for oxygen.

Anyone here able to point me to something that has this answer? or anyone here know the answer, even if it's not specifically been published yet?

I'm interested in the subject, but don't know where to begin investigating it. I tried to look over the code for SeDuMi, but it is much more massive than I had realized. I have a background in mathematics, if anyone can point me towards a textbook.

This is something weird to me. I think skin color is pretty diverse no matter where you go, or at least, I don't know enough to say otherwise. But take hair color. Europe has more diversity in hair color than almost anywhere else. Same with eye color. Why is this? Is it just because I interact with more people of European heritage on day to day business, or has Europe actually had more mutations which affect hair color, eye color, etc? Or is it that Europe, being a crossroads has had more people immigrate through it.

If this is racist, it's unintentional, this is just an observation, which I've been unable to find an answer to.

If you have an answer, a link to a paper would be great.

Edit: A point against what I just wrote that I thought of: Asia has both mono and double eyelids, which is something Europe doesn't have. Native americans don't count either for or against, since they immigrated fairly late in a small group, which also explains why almost all native americans are type O

Does there exist a function that does not include any trigonometric function in its definition that has similar properties (periodicity, for instance) as trigonometric functions? I can't think of any, and this strikes me as a bit surprising.

Edit: I thought of a simple answer: piecewise functions can achieve this!

I suck at probability, so I thought I would ask here.

To clarify, given a population of size P, a sample size of K, and an arbitrary number of trials N, how do I compute the probability of having included each member of the population at least once in the experiment?

This problem is difficult to wrap my head around. It seems like it uses a combination of combinatorics and dependent events, which really throws me off.

Edit: This problem isn't the coupon collector's problem (please see some of my responses below). Think of the coupon collector's problem as being a special case of this problem where K = 1. My question is meant to cover an arbitrary K >= 1.